424B4 1 a2239817z424b4.htm 424B4

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Table of Contents
Index to Financial Statements

Filed Pursuant to Rule 424(b)4
Registration No. 333-233662

PROSPECTUS

5,666,667 Shares

LOGO

Common Stock



        This is Aprea Therapeutics, Inc.'s initial public offering. We are selling 5,666,667 shares of our common stock in this offering. The initial public offering price of our common stock is $15.00 per share.

        Prior to this offering, there has been no market for our common stock. Our common stock has been approved for listing on the Nasdaq Global Select Market under the symbol "APRE."

        We are an "emerging growth company" and a "smaller reporting company" under federal securities laws and are subject to reduced public company disclosure standards for this prospectus and future filings. See "Summary—Implications of Being an Emerging Growth Company and Smaller Reporting Company."

        Investing in the common stock involves risks that are described in the "Risk Factors" section beginning on page 12 of this prospectus.



        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

 
  Per share   Total  

Public offering price

  $ 15.00   $ 85,000,005  

Underwriting discount(1)

  $ 1.05   $ 5,950,000  

Proceeds, before expenses, to us

  $ 13.95   $ 79,050,005  

(1)
We have agreed to reimburse the underwriters for certain FINRA-related expenses. We refer you to "Underwriting" beginning on page 188 of this prospectus for additional information regarding underwriting compensation.

        The underwriters may also exercise their option to purchase up to an additional 850,000 shares from us, at the public offering price, less underwriting discounts and commissions, within 30 days after the date of this prospectus.

        The shares will be ready for delivery on or about October 7, 2019.



Joint Book-Running Managers

J.P. Morgan   Morgan Stanley   RBC Capital Markets



   

The date of this prospectus is October 2, 2019.



Explanatory Note

        On September 20, 2019, we consummated the corporate reorganization as described in this prospectus under the section titled "Corporate Reorganization," pursuant to which all of the issued and outstanding stock and options of Aprea Therapeutics AB, a corporation domiciled in Sweden, were exchanged for common stock, preferred stock or options, as applicable, of Aprea Therapeutics, Inc., the issuer of the common stock being offered in this offering. As a result of this corporate reorganization, Aprea Therapeutics AB became a wholly-owned subsidiary of Aprea Therapeutics, Inc., a recently formed holding company with nominal assets and no liabilities, contingencies, or commitments, which has not conducted any operations prior to this offering other than acquiring the entire issued and outstanding stock of Aprea Therapeutics AB.

        We refer to these transactions throughout the prospectus included in this registration statement collectively as the "Holdco Reorganization." See "Corporate Reorganization" for further detail regarding these transactions.

        The audited consolidated financial statements for 2017 and 2018 and the notes thereto, the unaudited interim condensed consolidated financial statements for the six months ended June 30, 2019 and 2018 and the notes thereto, and selected historical consolidated financial data and other financial information included in this registration statement are those of Aprea Therapeutics AB and do not give effect to the Holdco Reorganization. The balance sheet of Aprea Therapeutics, Inc. at July 11, 2019, included in this registration statement, does not give effect to the Holdco Reorganization.

        Immediately prior to the completion of this offering, and with the consent of shareholders representing a majority of our outstanding preferred shares, all outstanding shares of our convertible preferred stock, including the shares issued as part of the Holdco Reorganization, will convert into an aggregate of 13,028,292 shares of our common stock. Shares of the common stock of Aprea Therapeutics, Inc. are being offered by the prospectus included in this registration statement.



Table of Contents

 
  Page  

Summary

    1  

Risk Factors

    12  

Special Note Regarding Forward-Looking Statements

    75  

Use of Proceeds

    77  

Dividend Policy

    78  

Corporate Reorganization

    79  

Capitalization

    80  

Dilution

    82  

Selected Financial Data

    85  

Management's Discussion and Analysis of Financial Condition and Results of Operations

    86  

Business

    102  

Management

    153  

Executive Compensation

    162  

Principal Stockholders

    173  

Description of Capital Stock

    176  

Shares Eligible for Future Sale

    181  

Material U.S. Federal Income Tax Considerations to Non-U.S. Holders

    184  

Underwriting

    188  

Legal Matters

    196  

Experts

    196  

Where You Can Find More Information

    196  

Index to Financial Statements

    F-1  

        Through and including October 27, 2019 (the 25th day after the date of this prospectus), all dealers that effect transactions in these securities, whether or not participating in this offering, may be required to deliver a prospectus. This is in addition to the dealers' obligation to deliver a prospectus when acting as underwriters and with respect to their unsold allotments or subscriptions.

        We are responsible for the information contained in this prospectus. We have not, and the underwriters have not, authorized anyone to provide you with any information other than what is provided in this prospectus. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you or any representation that others may make to you. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. The information in this prospectus is accurate only as of the date of this prospectus, regardless of the time of any sale of the common stock. Our business, liquidity position, financial condition, prospects or results of operations may have changed since the date of this prospectus.

        This prospectus contains forward-looking statements that are subject to a number of risks and uncertainties, many of which are beyond our control. See "Risk Factors" and "Special Note Regarding Forward-Looking Statements."

        For investors outside the United States: We have not, and the underwriters have not, done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside

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the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the shares of common stock and the distribution of this prospectus outside the United States.

        In this prospectus, unless otherwise stated or the context otherwise requires, references to "Aprea," "the company," "we," "us," "our" and similar references refer to Aprea Therapeutics, Inc. and its consolidated subsidiaries, after giving effect to the Holdco Reorganization, and to Aprea Therapeutics AB and its consolidated subsidiaries prior to giving effect to the Holdco Reorganization.

Presentation of financial and operating data

        Unless otherwise indicated, the historical financial and operating information presented in this prospectus as of and for the years ended December 31, 2017 and 2018 and for the six months ended June 30, 2018 and 2019 is that of Aprea Therapeutics AB.

        Certain amounts and percentages included in this prospectus have been rounded. Accordingly, in certain instances, the sum of the numbers in a column of a table may not exactly equal the total figure for that column.

        The audited consolidated financial statements for the years ended December 31, 2017 and 2018 and the notes thereto, the unaudited interim condensed consolidated financial statements for the six months ended June 30, 2018 and 2019 and the notes thereto, represent the operations of Aprea Therapeutics AB and its consolidated subsidiaries and do not give effect to the Holdco Reorganization. The balance sheet of Aprea Therapeutics, Inc. at July 11, 2019, included in this registration statement, does not give effect to the Holdco Reorganization. On September 20, 2019, we consummated the corporate reorganization as described under the section titled "Corporate Reorganization." In this prospectus, we refer to this transaction as the "Holdco Reorganization." We expect that the Holdco Reorganization will not have a material effect on our consolidated financial statements.

Industry and market data

        We obtained the industry, market and competitive position data used throughout this prospectus from our own internal estimates and research, as well as from independent market research, industry and general publications and surveys, governmental agencies and publicly available information in addition to research, surveys and studies conducted by third parties. Internal estimates are derived from publicly available information released by industry analysts and third-party sources, our internal research and our industry experience, and are based on assumptions made by us based on such data and our knowledge of our industry and market, which we believe to be reasonable. In some cases, we do not expressly refer to the sources from which this data is derived. In that regard, when we refer to one or more sources of this type of data in any paragraph, you should assume that other data of this type appearing in the same paragraph is derived from the same sources, unless otherwise expressly stated or the context otherwise requires. In addition, while we believe the industry, market and competitive position data included in this prospectus is reliable and based on reasonable assumptions, such data involve risks and uncertainties and are subject to change based on various factors, including those discussed in "Risk Factors." These and other factors could cause results to differ materially from those expressed in the estimates made by third parties or by us.

Trademarks and tradenames

        Aprea and other trademarks or service marks of Aprea appearing in this prospectus are the property of Aprea. The other trademarks, trade names and service marks appearing in this prospectus are the property of their respective owners. Solely for convenience, the trademarks and trade names in this prospectus are referred to without the ® and ™ symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto.

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Summary

        This summary highlights, and is qualified in its entirety by, the more detailed information and financial statements included elsewhere in this prospectus. This summary does not contain all of the information that may be important to you. You should read and carefully consider the entire prospectus, especially our financial statements and the notes thereto appearing at the end of this prospectus and the "Risk Factors" section of this prospectus, before deciding to invest in our common stock. Except as otherwise indicated herein or as the context otherwise requires, references in this prospectus to "Aprea," "the company," "we," "us" and "our" refer to Aprea Therapeutics, Inc. and its consolidated subsidiaries, after giving effect to the Holdco Reorganization described herein, and to Aprea Therapeutics AB, referred to herein as Aprea AB, and its consolidated subsidiaries prior to giving effect to the Holdco Reorganization.

Aprea Therapeutics overview

        We are a clinical-stage biopharmaceutical company focused on developing and commercializing novel cancer therapeutics that reactivate mutant p53 tumor suppressor protein. p53 is the protein expressed from the TP53 gene, the most commonly mutated gene in cancer. We believe that mutant p53 is an attractive therapeutic target due to the high incidence of p53 mutations across a range of cancer types and its involvement in key cellular activities such as apoptosis. Cancer patients with mutant p53 face a significantly inferior prognosis even when treated with the current standard of care, and a large unmet need for these patients remains. Our lead product candidate, APR-246, is a small molecule p53 reactivator that is in late-stage clinical development for hematologic malignancies, including myelodysplastic syndromes, or MDS, and acute myeloid leukemia, or AML. APR-246 has received Orphan Drug and Fast Track designations from the FDA for MDS, and Orphan Drug designation from the EMA for MDS, AML and ovarian cancer, and we believe APR-246 will be a first-in-class therapy if approved by applicable regulators. We have commenced a pivotal Phase 3 trial of APR-246 with azacitidine for frontline treatment of TP53 mutant MDS and expect initial data from this trial in the second half of 2020. Our pivotal Phase 3 trial is supported by data from two ongoing Phase 1b/2 investigator initiated trials, one in the U.S. and one in France, testing APR-246 with azacitidine as frontline treatment in TP53 mutant MDS and AML patients.

        In the ongoing U.S. Phase 1b/2 trial, sponsored by Dr. David Sallman of the H. Lee Moffitt Cancer Center and Research Institute, or Moffitt, we have observed an objective response rate, or ORR, of 88% and a complete remission, or CR, rate of 59% in 41 response-evaluable MDS/AML patients treated with APR-246 and azacitidine, as of July 2019 and we expect a final CR endpoint in the second half of 2019. In MDS patients, the CR rate was 61%, with an additional 27% achieving non-CR responses. In AML patients, the CR rate was 50%, with an additional 38% achieving non-CR responses. In addition, 46% of evaluable patients were able to discontinue treatment in order to proceed to allogeneic hematopoietic stem cell transplantation, or allo-HCT. Allo-HCT is currently the only recognized therapy believed to increase the likelihood of long term survival for TP53 mutant MDS and AML patients in remission. In the ongoing French Phase 1b/2 trial, sponsored by Groupe Francophone des Myelodysplasies, or GFM, under lead investigator Prof. Pierre Fenaux, we have observed an ORR of 75% and a CR rate of 56% in 16 response-evaluable patients treated with APR-246 and azacitidine, as of July 2019 and we expect a final CR endpoint in the first half of 2020. In MDS patients, the CR rate was 55%, with an additional 18% achieving non-CR responses. In AML patients, the CR rate was 60%, with an additional 20% achieving non-CR responses. We expect the results of our pivotal Phase 3 trial and the U.S. and French Phase 1b/2 trials will be submitted in support of marketing applications to the FDA and EMA. We are also developing a next-generation small molecule p53 reactivator, APR-548, for potential use in multiple hematologic malignancies and other oncologic indications, and expect to file an IND with the FDA in the first half of 2020. We


 

currently retain global development and commercialization rights to all of our preclinical and clinical product candidates, which are summarized in the following figure:

GRAPHIC


(1)
Investigator-initiated trial

(2)
With or without azacitidine

        We believe that targeting p53 and thereby reactivating key intrinsic cellular functions has the potential to significantly impact patients' lives and treatment strategies for a wide variety of cancers. p53 is a tumor suppressor protein that in its normal state functions to sense DNA damage and induce cell cycle arrest, DNA damage repair, senescence and cellular apoptosis. Mutant p53 is an attractive target because it is widely mutated across hematologic and solid tumors and is associated with an aggressive clinical and molecular phenotype. In preclinical studies and clinical trials, mutations in p53 and the apoptotic pathway have been shown to play a key role in cancer genesis, proliferation and resistance to currently marketed therapeutic agents. Many approved and clinical stage oncology drugs are more effective with a functional p53 pathway. Our approach is to restore normal function to p53, thereby re-enabling a cell's ability to undergo apoptosis. Accordingly, we believe that by targeting p53, our drug candidates may enhance the ability of other anti-cancer therapies to induce cancer cell death. In addition, we believe that our approach may counteract resistance mechanisms that characterize many of the most aggressive cancers.

        We believe there is a significant market opportunity for therapies targeting mutant p53 because these mutations occur in more than half of all tumors and confer an inferior prognosis relative to patients with wild type p53. Based on the importance of p53 mutations as disease-driver mutations, the sensitivity of hematopoietic cells to oxidative stress and continued unmet medical need, we have initially focused our clinical development on hematological malignancies, MDS and AML, with mutations in the TP53 gene.

        MDS is a collection of bone marrow disorders in which malignant hematopoietic cells prevent the production of healthy, mature blood cells. As of 2019, there are an estimated 200,000 MDS patients

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worldwide, with 68,000 of these in the United States and 69,000 MDS patients across the five major markets of the European Union and Japan.

        AML is the most common form of adult leukemia, with the highest incidence in patients age 60 years and older. Like MDS, AML is characterized by proliferation of abnormal immature white blood cells which impair production of normal blood cells. There are an estimated 213,000 AML patients worldwide, with 37,000 of these in the United States, and 41,000 across the five major markets of the European Union and Japan.

        MDS and AML can develop de novo or may arise secondary to progression of other hematologic disorders or from chemotherapy or radiation treatment for a different, prior malignancy. Secondary MDS and AML carry a worse prognosis than de novo disease. Mutations in TP53 occur in approximately 20% of patients with newly diagnosed MDS/AML and in more than 30% of patients with therapy-related MDS/AML.

        Treatment with azacitidine is the standard of care for frontline therapy in TP53 mutant MDS and AML, with an ORR of approximately 40-50%, a CR rate of approximately 10-20% and median overall survival, or OS, of approximately 7-8 months. There are no established curative pharmacologic therapies for MDS and AML. Allo-HCT is currently the only recognized therapy believed to increase the likelihood of long term survival for TP53 mutant MDS and AML patients in remission; however, many patients are not candidates for allo-HCT due to lack of sufficient clinical response to therapy, advanced age, comorbidities or lack of a suitable donor. Unfortunately, even for those TP53 mutant MDS and AML patients who receive allo-HCT, the post-transplantation prognosis is poor: TP53 mutations are associated with a 4-fold increased risk of death and 1-year relapse-free survival of only 30% following transplantation.

        Given the poor prognosis for patients with TP53 mutant MDS and AML, there is a significant need for more effective therapies in this population, particularly if such treatments have a favorable safety profile, and a mechanism of action that targets mutant p53 directly, and may be used in combination with existing or future treatment options.

        We have assembled an outstanding team, which includes world-class scientific and clinical oncology leaders, to execute on our mission to create novel p53-reactivating therapies to help patients suffering with cancer. Together with our board of directors, our scientific founders and members of our management team have significant experience in drug discovery and development and finance. Collectively, we believe our team's strong capabilities position us to build a leading biotech company focused on developing novel cancer therapies to address the significant unmet medical need of patients with p53 mutant malignancies, for whom there are limited effective therapeutic options.

Our drug candidates

        Our lead product candidate, APR-246, is a small molecule that has demonstrated reactivation of mutant p53 in clinical trials. Promising clinical data support the application of APR-246 across a variety of hematologic malignancies and other oncologic indications. APR-246 is a pro-drug that is administered intravenously and forms the active moiety, 2-methylene-quinuclidin-3-one, or MQ, under physiological conditions. APR-246 has been shown to induce apoptosis in cancer cells with mutant p53 in Phase 1/2 trials. We believe the mechanism of action and current adverse event profile of APR-246 may provide the basis for its combination with both conventional and novel therapies, such as targeted therapies, chemotherapy, radiotherapy and immuno-therapy. APR-246 has received Orphan Drug and Fast Track designations from the FDA for MDS, and Orphan Drug designation from the EMA for MDS, AML and ovarian cancer.

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        We are conducting and supporting multiple clinical trials of APR-246:

    Pivotal Phase 3 MDS Trial- We are currently enrolling a pivotal Phase 3 randomized, controlled trial evaluating APR-246 with azacitidine as frontline therapy in HMA-naïve TP53 mutant MDS patients. The first patient was enrolled in January 2019 and we anticipate full enrollment in our Phase 3 trial in the first quarter of 2020 and top-line data from this trial in the second half of 2020.

    U.S. Phase 1b/2 MDS/AML Trial- We are supporting an investigator-initiated Phase 1b/2 single-arm, open-label trial in the United States, sponsored by Dr. David Sallman of the H. Lee Moffitt Cancer Center and Research Institute, or Moffitt, evaluating APR-246 with azacitidine as frontline therapy in HMA-naïve patients with TP53 mutant MDS or AML. We are collaborating with Moffitt on this trial by supplying APR-246, in addition to providing financial support. The primary endpoint of the trial is CR rate and enrollment has completed with 55 patients. Top-line results on the CR rate primary endpoint and median duration of response are expected in the second half of 2019. The regimen achieved an ORR of 88% and a CR rate of 59% in 41 response-evaluable patients as of July 2019. In MDS patients, the CR rate was 61%, with an additional 27% achieving non-CR responses. In AML patients, the CR rate was 50%, with an additional 38% achieving non-CR responses. In addition, 46% of evaluable MDS/AML patients were able to discontinue treatment in order to proceed to allo-HCT. By intention-to-treat analysis, and with a median follow up of 10.5 months, median OS was 11.6 months (95% confidence interval: 9.2 - 14.0 months) with significantly prolonged OS of 12.8 months in responding patients versus 3.9 months in non-responding patients (p <0.0001).

    French Phase 1b/2 MDS/AML Trial- We are supporting a parallel investigator-initiated Phase 1b/2 single-arm, open-label trial in France, sponsored by Groupe Francophone des Myelodysplasies, or GFM, under lead investigator Prof. Pierre Fenaux, evaluating APR-246 with azacitidine as frontline therapy in HMA-naïve patients with TP53 mutant MDS or AML. We are collaborating with GFM on this trial by supplying APR-246, in addition to providing financial support. The primary endpoint of the trial is CR rate and enrollment has completed with 53 patients. Top-line results on the CR rate primary endpoint are expected in the first half of 2020. All patients are to receive the recommended Phase 2 dose from the U.S. Phase 1b/2 MDS/AML Trial. As of July 2019, the regimen has achieved an ORR of 75% and CR rate of 56% in 16 response-evaluable patients. In MDS patients, the CR rate was 55%, with an additional 18% achieving non-CR responses. In AML patients, the CR rate was 60%, with an additional 20% achieving non-CR responses. Responding patients who proceed to allo-HCT are eligible to continue receiving APR-246 with azacitidine as post-transplant maintenance therapy.

    Phase 2 MDS/AML Post-Transplant Trial- We are currently enrolling our single-arm, open-label Phase 2 trial evaluating APR-246 with azacitidine as post-transplant maintenance therapy in TP53 mutant MDS and AML patients who have received allo-HCT. The primary endpoint is relapse-free survival at 12 months. We anticipate full enrollment in the first half of 2020.

    Phase 1/2 AML Trials- Based on in vitro data evidencing synergistic activity between APR-246 and a Bcl-2 inhibitor, we have designed and plan to conduct Phase 1/2 clinical trials in frontline and relapsed/refractory AML assessing APR-246 with a Bcl-2 inhibitor with or without azacitidine. We anticipate the first patient to be enrolled in the fourth quarter of 2019.

        Our second product candidate, APR-548, is a next-generation p53 reactivator with the potential for oral administration. APR-548 is a unique analog of APR-246 and therefore a pro-drug of MQ. We have filed a patent application in support of composition of matter and methods of use intellectual property protection for APR-548. APR-548 exhibits high oral bioavailability in preclinical testing and is being developed in an oral dosage form. We are currently conducting Investigational New Drug, or IND, enabling preclinical trials of APR-548 and anticipate submitting an IND in the first half of 2020.

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Our strategy

        Our mission is to be the leading player in the development and commercialization of p53-targeted cancer therapies. The key elements of our strategy are to:

    Rapidly develop and commercialize our lead mutant p53 reactivator product candidate, APR-246, in frontline combination therapy for TP53 mutant MDS

    Expand the clinical opportunity for APR-246 by pursuing development of combination therapy for post-transplant maintenance in TP53 mutant MDS and AML

    Rapidly develop APR-246 for frontline and relapsed/refractory TP53 mutant AML

    Advance our next-generation p53 reactivator, APR-548

    Explore additional oncology indications for APR-246 and APR-548

    Maximize the commercial opportunity of our product candidates across global markets

Risks associated with our business

        Our ability to execute on our business strategy is subject to a number of risks, which are discussed more fully in the section of this prospectus entitled "Risk Factors." You should carefully consider these risks before making an investment in our common stock. These risks include, among others, the following:

    We have incurred significant losses since inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability. As of June 30, 2019, we had an accumulated deficit of $71.2 million.

    Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability. We have never generated revenues and may never be profitable. Our lead product candidate, APR-246, is currently in multiple clinical trials and all of our other product candidates are in preclinical research.

    We believe that the net proceeds from this offering, together with our existing cash and cash equivalents, will enable us to fund our operating expenses and capital expenditure requirements into 2023. We expect that the net proceeds from this offering and our existing cash and cash equivalents will be sufficient to enable us to complete each of our ongoing clinical trials. We do not expect that the net proceeds from this offering and our existing cash and cash equivalents will be sufficient, however, to enable us to conduct through completion any additional clinical trials of APR-246 or to otherwise complete the development of APR-246. Accordingly, we will need substantial additional funding, which may not be available to us on acceptable terms or at all, to complete development of APR-246 and to fund development of our next-generation p53 reactivator, APR-548. If we are unable to raise capital when needed, we may be forced to delay, reduce and/or eliminate our research and drug development programs or commercialization efforts.

    We are substantially dependent on the success of APR-246 and cannot be certain that we will receive marketing approval for APR-246 or will successfully commercialize APR-246 even if we receive such marketing approval.

    If we experience delays or difficulties in the enrollment of patients in clinical trials, we may not be able to initiate or complete clinical trials for our product candidates on a timely basis.

    The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results.

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    If clinical trials of our product candidates fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs, experience delays in completing, or ultimately be unable to complete, the development of our product candidates or be unable to obtain marketing approval.

    We rely on third parties to conduct our clinical trials, some aspects of our research and preclinical studies and the manufacturing of our product candidates. If these third parties do not perform satisfactorily, including by failing to meet deadlines for the completion of such trials, research and studies, we could be delayed in our clinical development activities or in our efforts to obtain marketing approval of our product candidates.

    The chemical structure of APR-246 is in the public domain. Accordingly, we do not own or license any composition of matter patents claiming the compound of APR-246 and will not in the future own or license any composition of matter patents claiming the chemical structure of APR-246 as described in the public domain. Our patent portfolio for APR-246 currently consists of method-of-use and formulation patent claims, and dosing, manufacturing processes, and crystalline solid form provisional patent application claims. If we are unable to obtain or maintain patent and other intellectual property-related protection of our proprietary technologies and our product candidates, including APR-246, their respective components, formulations, methods used to manufacture them and methods of treatment, if the scope of the patent protection obtained is not sufficiently broad, or if we are unable to successfully defend our patents against third-party challenges or enforce our patents against third-parties, our competitors and other third parties could develop and commercialize products and technology similar or identical to ours, and our ability to successfully commercialize any product candidate we may develop and our technology may be adversely affected.

    Our commercial success depends in part on the ability to avoid and successfully defend claims that we have infringed, misappropriated or otherwise violated the intellectual property of a third party.

Our corporate information

        We were incorporated under the laws of the State of Delaware in May 2019 under the name Aprea Therapeutics, Inc. On September 20, 2019, we consummated the Holdco Reorganization, pursuant to which all of the issued and outstanding stock and options of Aprea Therapeutics AB, or Aprea AB, were exchanged for common stock, preferred stock or options, as applicable, of Aprea Therapeutics, Inc. As a result of the HoldCo Reorganization, Aprea AB, became a wholly-owned subsidiary of Aprea Therapeutics, Inc. See "Corporate Reorganization" for additional information.

        We are a holding company. We conduct substantially all of our operations through our subsidiaries. Our subsidiary, Aprea AB, a corporation domiciled in Sweden, was originally incorporated in 2002 and commenced principal operations in 2006, and holds substantially all of our intellectual property assets. Our executive offices are located at 535 Boylston Street, Boston, MA 02116, and our telephone number is 617-463-9385. Our website address is www.aprea.com. The information contained on, or that can be accessed through, our website is not a part of this prospectus. We have included our website address in this prospectus solely as an inactive textual reference.

Implications of being an emerging growth company and smaller reporting company

        As a company with less than $1.07 billion of revenue during our last fiscal year, we qualify as an "emerging growth company" as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. We may remain an emerging growth company for up to five years, or until such earlier time as we have more than $1.07 billion in annual revenue, the market value of our stock held by non-affiliates is more than $700 million (and we have been a public company for at least 12 months

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and have filed one annual report on Form 10-K with the Securities and Exchange Commission, or the SEC) or we issue more than $1 billion of non-convertible debt over a three-year period. For so long as we remain an emerging growth company, we are permitted and intend to rely on exemptions from certain disclosure and other requirements that are applicable to other public companies that are not emerging growth companies. These provisions include:

    reduced disclosure about our executive compensation arrangements;

    exemption from the non-binding stockholder advisory votes on executive compensation or golden parachute arrangements;

    exemption from the auditor attestation requirement in the assessment of our internal control over financial reporting; and

    reduced disclosure of financial information in this prospectus, such as being permitted to include only two years of audited financial information and two years of selected financial information in addition to any required unaudited interim financial statements, with correspondingly reduced "Management's Discussion and Analysis of Financial Condition and Results of Operations" disclosure.

        We have taken advantage of some reduced reporting burdens in this prospectus. Accordingly, the information contained herein may be different than the information you receive from other public companies in which you hold stock. In addition, the JOBS Act permits an emerging growth company to take advantage of an extended transition period to comply with new or revised accounting standards applicable to public companies until those standards would otherwise apply to private companies. We have irrevocably elected not to avail ourselves of this exemption and, as a result, upon completion of this offering we will adopt new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies that are not emerging growth companies.

        We are also a "smaller reporting company," as such term is defined in Rule 12b-2 under the Securities Exchange Act of 1934, or the Exchange Act, meaning that the market value of our common stock held by non-affiliates plus the proposed aggregate amount of gross proceeds to us as a result of this offering is less than $700 million and our annual revenue is less than $100 million during the most recently completed fiscal year. We may continue to be a smaller reporting company after this offering if either (i) the market value of our common stock held by non-affiliates is less than $250 million or (ii) our annual revenue is less than $100 million during the most recently completed fiscal year and the market value of our common stock held by non-affiliates is less than $700 million. If we are a smaller reporting company at the time we cease to be an emerging growth company, we may continue to rely on exemptions from certain disclosure requirements that are available to smaller reporting companies. Specifically, as a smaller reporting company we may choose to present only the two most recent fiscal years of audited financial statements in our Annual Report on Form 10-K and, similar to emerging growth companies, smaller reporting companies have reduced disclosure obligations regarding executive compensation.

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The Offering

Common stock offered by us

  5,666,667 shares

Underwriters' option to purchase additional shares

 

We have granted the underwriters a 30-day option to purchase up to 850,000 additional shares at the public offering price, less underwriting discounts and commissions.

Common stock to be outstanding after the offering

 

19,876,532 shares (or 20,726,532 shares if the underwriters exercise in full their option to purchase additional shares)

Use of proceeds

 

We estimate that our net proceeds from this offering, after deducting underwriting discounts and commissions and estimated offering expenses payable by us, will be approximately $75.9 million, or $87.7 million if the underwriters exercise their option to purchase additional shares in full. We intend to use the net proceeds from the offering to fund: (i) future Phase 1b/2 clinical studies of APR-246 for solid tumor and hematological malignancies as well as additional future clinical studies to be determined if the data derived from such Phase 1b/2 clinical studies is favorable; (ii) continued research and development activities for APR-548, including ongoing IND-enabling studies and a first-in-human clinical trial; (iii) the ongoing preclinical and clinical development of APR-246, including preparation and submission of a New Drug Application (NDA) in MDS; and (iv) general research and development activities, working capital and other general corporate activities including the buildout of infrastructure to support the advancement of our product candidates. See "Use of Proceeds" on page 77 for a more complete description of the intended use of proceeds from this offering.

Directed share program

 

The underwriters have reserved up to 3% of the shares of common stock being offered by this prospectus (excluding the shares of common stock that may be issued upon the underwriters' exercise of their option to purchase additional common stock) for sale to our directors, officers, employees, business associates and related persons of the Company. The number of shares of common stock available for sale to the general public will be reduced to the extent these individuals purchase such reserved shares. Any reserved shares that are not so purchased will be offered by the underwriters to the general public on the same basis as the other shares offered by this prospectus. See "Underwriting—Directed Share Program."

Risk factors

 

See the "Risk Factors" section beginning on page 12 of this prospectus, as well as other information included in this prospectus for a discussion of factors to consider carefully before deciding to invest in shares of our common stock.

Nasdaq Global Select Market symbol

 

"APRE"

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        The number of shares of our common stock to be outstanding after the completion of this offering is based on 14,209,865 shares outstanding as of June 30, 2019, after giving effect to the Holdco Reorganization which took place on September 20, 2019 and the 1 for 1.6045 split of our common stock which took place on September 26, 2019 and assumes the conversion of our outstanding convertible preferred stock into 13,028,292 shares of common stock immediately prior to the completion of this offering, and excludes:

    2,761,794 shares of common stock, with a weighted-average exercise price of $1.66 per share, issuable upon exercise of stock options outstanding as of June 30, 2019 under our 2016 Stock Incentive Plan; and

    2,488,206 shares of common stock reserved for issuance pursuant to future awards under our 2019 Stock Incentive Plan or our Employee Stock Purchase Plan, plus any future increases in the number of shares of common stock reserved for issuance under our 2019 Stock Incentive Plan or our Employee Stock Purchase Plan pursuant to provisions thereof that automatically increase the share reserve under the plan each year.

        Unless otherwise indicated or the context otherwise requires, information in this prospectus reflects and assumes the following:

    the 1 for 1.6045 split of our common stock which took place on September 26, 2019;

    the issuance of 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration office on August 27, 2019;

    no exercise of outstanding options or warrants;

    the completion of the Holdco Reorganization;

    no exercise by the underwriters of their option to purchase up to an additional 850,000 shares of our common stock;

    the conversion of all of our outstanding shares of convertible preferred stock into an aggregate of 13,028,292 shares of common stock immediately prior to the completion of this offering; and

    the filing and effectiveness of our amended and restated certificate of incorporation, which will occur immediately prior to the completion of this offering.

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Summary Financial Data

        You should read the following summary financial data together with our financial statements and the related notes appearing at the end of this prospectus and the "Selected Financial Data" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of this prospectus. We have derived the statement of operations data for the years ended December 31, 2017 and 2018 and the balance sheet data as of December 31, 2018 from our audited financial statements appearing at the end of this prospectus. The consolidated statements of operations data for the six months ended June 30, 2018 and 2019 and the consolidated balance sheet data at June 30, 2019 are derived from our unaudited condensed consolidated financial statements included in this prospectus. The unaudited condensed consolidated financial statements include, in the opinion of management, all adjustments that management considers necessary for the fair presentation of the consolidated financial information set forth in those statements. Our historical results are not necessarily indicative of results that should be expected in any future period.

 
  Years ended December 31,   Six months ended June 30,  
 
  2017   2018   2018   2019  
 
   
   
  (unaudited)
 

Consolidated Statement of Operations Data:

                         

Operating expenses:

                         

Research and development

  $ 13,392,631   $ 14,194,732   $ 7,492,788   $ 7,998,270  

General and administrative

    2,459,744     2,294,671     1,166,520     2,347,915  

Total operating expenses

    15,852,375     16,489,403     8,659,308     10,346,185  

Other income (expense):

                         

Interest expense

    (15 )   (182 )   (188 )   (7,439 )

Foreign currency gain

    662,140     961,316     949,158     1,615,974  

Total other income (expense)

    662,125     961,134     948,970     1,608,535  

Net loss

  $ (15,190,250 ) $ (15,528,269 ) $ (7,710,338 ) $ (8,737,650 )

Net loss per share attributable to common stockholders, basic and diluted(1)

  $ (13.17 ) $ (13.45 ) $ (6.68 ) $ (7.43 )

Weighted average common shares outstanding, basic and diluted(1)

    1,153,069     1,154,368     1,154,107     1,176,417  

Pro forma net loss per share attributable to common stockholders, basic and diluted (unaudited)(1)

        $ (1.65 )       $ (0.62 )

Pro forma weighted average common shares outstanding, basic and diluted (unaudited)(1)

          9,428,873           14,075,669  

(1)
See Note 2 to our audited and unaudited interim financial statements included elsewhere in this prospectus for an explanation of the method used to calculate basic and diluted net loss per share and unaudited pro forma net basic and diluted loss per share as well as the weighted-average number of shares used in the computation of the per share amounts.

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        The following table sets forth summary balance sheet data as of June 30, 2019:

    on an actual basis (including 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration Office on August 27, 2019);

    on a pro forma basis to give effect to (i) the Holdco Reorganization described under the section titled "Corporate Reorganization", (ii) the 1 for 1.6045 split of our common stock which took place on September 26, 2019, (iii) the conversion of all of our outstanding shares of convertible preferred stock into an aggregate of 13,028,292 shares of common stock immediately prior to the completion of this offering and (iv) the filing and effectiveness of our amended and restated certificate of incorporation; and

    on a pro forma as adjusted basis to give further effect to our issuance and sale of 5,666,667 shares of our common stock in this offering at the initial public offering price of $15.00 per share, after deducting underwriting discounts and commissions and estimated offering expenses payable by us.
 
  June 30, 2019  
 
  Actual   Pro forma   Pro forma
as adjusted
 

Consolidated Balance Sheet Data:

                   

Cash and cash equivalents

  $ 60,994,738   $ 60,994,738   $ 136,844,743  

Working capital(1)

    56,215,210     56,215,210     132,065,215  

Total assets

    62,214,654     62,214,654     138,064,659  

Total liabilities

    5,878,053     5,878,053     5,878,053  

Convertible preferred stock

    118,188,993          

Total stockholders' equity (deficit)

    (61,852,392 )   56,336,601     132,186,606  

(1)
We define working capital as current assets less current liabilities. See our financial statements for further details regarding our current assets and current liabilities.

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Risk Factors

        Investing in our common stock involves a high degree of risk. Before you decide to invest in our common stock, you should consider carefully the risks described below, together with the other information contained in this prospectus, including our financial statements and the related notes appearing at the end of this prospectus. We believe the risks described below are the risks that are material to us as of the date of this prospectus. If any of the following risks actually occur, our business, financial condition, results of operations and future growth prospects could be materially and adversely affected. In these circumstances, the market price of our common stock could decline, and you may lose all or part of your investment.

Risks related to our financial position and need for additional capital

We have incurred significant losses in each year since inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.

        Since our inception, we have incurred significant losses on an aggregate basis. Our net loss was $8.7 million for the six months ended June 30, 2019, and $15.5 million for the year ended December 31, 2018. Our accumulated deficit was $71.2 million as of June 30, 2019 and $62.5 million as of December 31, 2018. We have not generated any revenue to date from sales of any drugs and have financed our operations principally through private placements of our preferred stock. We have devoted substantially all of our efforts to research and development. Our lead product candidate, APR-246, is in clinical development, and our other product candidates are in preclinical research. As a result, we expect that it will be several years, if ever, before we have any product candidates ready for commercialization. We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. The net losses we incur may fluctuate significantly from quarter to quarter.

        To become and remain profitable, we must develop, obtain approval for and eventually commercialize a drug or drugs with significant market potential, either on our own or with a collaborator. This will require us to be successful in a range of challenging activities, including completing preclinical studies and clinical trials of our product candidates, obtaining marketing approval for these product candidates, manufacturing, marketing and selling those drugs for which we may obtain marketing approval and establishing and managing any collaborations for the development, marketing and/or commercialization of our product candidates. We may never succeed in these activities and, even if we do, may never generate revenues that are significant or large enough to achieve profitability. If we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would decrease the value of our company and could impair our ability to raise capital, maintain our research and development efforts, expand our business and/or continue our operations. A decline in the value of our company could also cause you to lose all or part of your investment.

        Even if we succeed in commercializing one or more of our product candidates, we will continue to incur substantial research and development and other expenditures to develop and market additional product candidates. We may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. The size of our future net losses will depend, in part, on the rate of future growth of our expenses and our ability to generate revenue. Our prior losses and expected future losses have had and will continue to have an adverse effect on our stockholders' equity and working capital.

        Our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of drugs that we do not expect to be commercially available for many years, if at all. If we are unable to obtain product approvals or generate significant commercial revenues, our business will be materially harmed.

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Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability. We have never generated revenues and may never be profitable.

        We are an early-stage company. Aprea Therapeutics AB, or Aprea AB, was originally incorporated in 2002 and commenced operations in 2006. We were incorporated in May 2019. Our operations to date have been limited to organizing and staffing our company, business planning, raising capital, developing our lead product candidate, APR-246, identifying potential product candidates, conducting preclinical studies of our product candidates and conducting clinical trials of our product candidates. All of our product candidates other than APR-246 are in preclinical research. We have not yet demonstrated our ability to successfully complete large-scale, pivotal clinical trials, obtain marketing approvals, manufacture commercial-scale drug products or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful drug commercialization. Typically, it takes about six to ten years to develop a new drug from the time it is in Phase 1 clinical trials to when it is approved for treating patients, but in many cases it may take longer. Consequently, any predictions you make about our future success or viability may not be as accurate as they could be if we had a longer operating history.

        In addition, as a business with a limited operating history, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors. We may need to transition from a company with a research focus to a company capable of supporting commercial activities. We may not be successful in such a transition.

        As we continue to build our business, we expect our financial condition and operating results may fluctuate significantly from quarter to quarter and year to year due to a variety of factors, many of which are beyond our control. Accordingly, you should not rely upon the results of any particular quarterly or annual periods as indications of future operating performance.

We will need substantial additional funding, which may not be available to us on acceptable terms or at all. If we are unable to raise capital when needed, we may be forced to delay, reduce and/or eliminate our research and drug development programs or future commercialization efforts.

        Developing drug products, including conducting preclinical studies and clinical trials, is a very time-consuming, expensive and uncertain process that takes years to complete. We expect our expenses to increase in connection with our ongoing activities, particularly as we conduct clinical trials of, and seek marketing approval for, APR-246 and our other product candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to drug sales, marketing, manufacturing and distribution to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time for any such product candidate. Furthermore, commencing upon the completion of this offering, we expect to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we may be forced to delay, reduce and/or eliminate our research and drug development programs or future commercialization efforts.

        We plan to use the net proceeds from this offering to fund our ongoing clinical trials of APR-246 and additional research and clinical development activity related to APR-246 and other programs and for working capital and other general corporate purposes, which may include additional research, hiring additional personnel, capital expenditures and the costs of operating as a public company. We will be required to expend significant funds in order to advance the development of APR-246, as well as any other product candidates. In any event, the net proceeds from this offering and our existing cash and cash equivalents will not be sufficient to fund all of the efforts that we plan to undertake or to fund the completion of development of any of our product candidates. Accordingly, we will be required to

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obtain further funding through public or private equity offerings, debt financings, collaborations and licensing arrangements or other sources. We do not have any committed external source of funds. Adequate additional financing may not be available to us on acceptable terms, or at all. Our failure to raise capital as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy.

        We believe that the net proceeds from this offering, together with our existing cash and cash equivalents, will enable us to fund our operating expenses and capital expenditure requirements into 2023. Our estimate as to how long we expect the net proceeds from this offering, together with our existing cash and cash equivalents, to be able to continue to fund our operations is based on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently expect. Further, changing circumstances, some of which may be beyond our control, could cause us to consume capital significantly faster than we currently anticipate, and we may need to seek additional funds sooner than planned. Our future capital requirements will depend on many factors, including:

    the scope, progress, results and costs of our current and future clinical trials of APR-246 for our current targeted indications;

    the scope, progress, results and costs of drug discovery, preclinical research and clinical trials for APR-246 and our other product candidates;

    the number of future product candidates that we pursue and their development requirements;

    the costs, timing and outcome of regulatory review of our product candidates;

    the extent to which we acquire or invest in businesses, products and technologies, including entering into or maintaining licensing or collaboration arrangements for product candidates on favorable terms, although we currently have no commitments or agreements to complete any such transactions;

    the costs and timing of future commercialization activities, including drug sales, marketing, manufacturing and distribution, for any of our product candidates for which we receive marketing approval, to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time;

    the amount of revenue, if any, received from commercial sales of our product candidates, should any of our product candidates receive marketing approval;

    the costs of preparing, filing and prosecuting patent applications, maintaining, defending and enforcing our intellectual property rights and defending intellectual property-related claims;

    our headcount growth and associated costs as we expand our business operations and our research and development activities; and

    the costs of operating as a public company.

Raising additional capital may cause dilution to our stockholders, including purchasers of common stock in this offering, restrict our operations or require us to relinquish rights to our product candidates.

        We expect our expenses to increase in connection with our planned operations. Until such time, if ever, as we can generate substantial revenues from the sale of drugs, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances and/or licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest may be diluted, and the terms of these securities could include liquidation or other preferences and anti-dilution protections that could adversely affect your rights as a common stockholder. In addition, debt financing, if available, would result in fixed

14


payment obligations and may involve agreements that include restrictive covenants that limit our ability to take specific actions, such as incurring additional debt, making capital expenditures, creating liens, redeeming stock or declaring dividends, that could adversely impact our ability to conduct our business. In addition, securing financing could require a substantial amount of time and attention from our management and may divert a disproportionate amount of their attention away from day-to-day activities, which may adversely affect our management's ability to oversee the development of our product candidates.

        If we raise additional funds through collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our technology, future revenue streams or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds when needed, we may be required to delay, reduce and/or eliminate our product candidate development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Risks related to the discovery, development and commercialization of our product candidates

We are substantially dependent on the success of our lead product candidate, APR-246, which is currently in multiple clinical trials. Our clinical trials of APR-246 may not be successful. If we are unable to obtain approval for and commercialize APR-246 or experience significant delays in doing so, our business will be materially harmed.

        Our future success is substantially dependent on our ability to timely obtain marketing approval for, and then successfully commercialize, APR-246, our lead product candidate. We are investing a majority of our efforts and financial resources in the research and development of APR-246. Our other product candidates are in earlier stages of development. Our business depends entirely on the successful development and commercialization of our product candidates. We currently have no drugs approved for sale and generate no revenues from sales of any products, and we may never be able to develop a marketable product.

        APR-246 will require additional clinical development, evaluation of clinical, preclinical and manufacturing activities, marketing approval in multiple jurisdictions, substantial investment and significant marketing efforts before we generate any revenues from product sales. We are not permitted to market or promote APR-246, or any other product candidates, before we receive marketing approval from the FDA and comparable foreign regulatory authorities, and we may never receive such marketing approvals.

        The success of APR-246 will depend on several factors, including the following:

    successful and timely completion of our ongoing clinical trials of APR-246;

    initiation and successful patient enrollment and completion of additional clinical trials on a timely basis;

    our ability to demonstrate APR-246's safety, tolerability and efficacy to the FDA or any comparable foreign regulatory authority for marketing approval;

    timely receipt of marketing approvals for APR-246;

    obtaining and maintaining patent protection, trade secret protection and regulatory exclusivity, both in the United States and internationally;

    successfully defending and enforcing our rights in our intellectual property portfolio;

    avoiding and successfully defending against any claims that we have infringed, misappropriated or otherwise violated any intellectual property of any third party;

15


    the performance of our future collaborators, if any;

    the extent of, and our ability to timely complete, any required post-marketing approval commitments imposed by FDA or other applicable regulatory authorities;

    establishment of supply arrangements with third-party raw materials and drug product suppliers and manufacturers who are able to manufacture clinical trial and commercial quantities of APR-246 drug substance and drug product and to develop, validate and maintain a commercially viable manufacturing process that is compliant with current good manufacturing practices, or cGMP, at a scale sufficient to meet anticipated demand and over time enable us to reduce our cost of manufacturing;

    establishment of scaled production arrangements with third-party manufacturers to obtain finished products that are compliant with cGMP and appropriately packaged for sale;

    successful launch of commercial sales following any marketing approval;

    a continued acceptable safety profile following any marketing approval;

    commercial acceptance by patients, the medical community and third-party payors;

    the availability of coverage and adequate reimbursement and pricing by third-party payors and government authorities;

    the availability, perceived advantages, relative cost, relative safety and relative efficacy of alternative and competing treatments; and

    our ability to compete with other therapies.

        We do not have complete control over many of these factors, including certain aspects of clinical development and the regulatory submission process, potential threats to our intellectual property rights and the manufacturing, marketing, distribution and sales efforts of any future collaborator. Accordingly, we cannot assure you that we will ever be able to generate revenue through the sale of APR-246. If we are not successful in commercializing APR-246, or are significantly delayed in doing so, our business will be materially harmed.

We may find it difficult to enroll patients in our clinical trials given the relatively smaller patient population who have the diseases for which our product candidates are being developed. If we experience delays or difficulties in the enrollment of patients in clinical trials, our receipt of necessary marketing approvals could be delayed or prevented.

        We may not be able to initiate or continue clinical trials for our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or comparable foreign regulatory authorities. Patient enrollment is a significant factor in the timing of clinical trials. In particular, because our clinical trials of APR-246 are focused on indications with relatively small patient populations, our ability to enroll eligible patients may be limited or may result in slower enrollment than we anticipate.

        Patient enrollment may be affected if our competitors have ongoing clinical trials for product candidates that are under development for the same indications as our product candidates, and patients who would otherwise be eligible for our clinical trials instead enroll in clinical trials of our competitors' product candidates. Patient enrollment may also be affected by other factors, including:

    size and nature of the patient population;

    severity of the disease under investigation;

    availability and efficacy of approved drugs for the disease under investigation;

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    patient eligibility criteria for the trial in question;

    patients' and clinicians' perceived risks and benefits of the product candidate under study;

    competing clinical trials;

    efforts to facilitate timely enrollment in clinical trials;

    patient referral practices of physicians;

    the ability to monitor patients adequately during and after treatment;

    proximity and availability of clinical trial sites for prospective patients; and

    continued enrollment of prospective patients by clinical trial sites.

        Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays or may require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our product candidates, which would cause the value of our company to decline and limit our ability to obtain additional financing.

The reactivation of p53 is a novel and unproven therapeutic approach and our development of APR-246 may never lead to a marketable product.

        We are developing APR-246 for its ability to reactivate the tumor suppressor protein p53, the protein product of the TP53 gene and the most commonly mutated gene in cancer. We are also developing a next-generation p53 reactivator, APR-548, for potential use in multiple hematologic malignancy indications. We believe that mutant p53 is an attractive target for novel cancer therapy due to the high incidence of p53 mutations across a range of cancer types and the universally inferior prognosis for cancer patients with mutated p53. However, to our knowledge, no one has advanced a product candidate with this mechanism of action into clinical development. The scientific evidence to support the feasibility of developing these product candidates is both preliminary and limited. For instance, even though APR-246 has shown promising results in preclinical studies and early-stage clinical trials, we may not succeed in demonstrating safety and efficacy of APR-246 in larger-scale clinical trials, including our pivotal Phase 3 clinical trial. Advancing APR-246 as a novel product to reactivate p53 creates significant challenges for us, including:

    obtaining marketing approval, as obtaining regulatory approval of a p53 reactivator from the FDA or comparable foreign regulatory authorities has never been done before;

    educating medical personnel regarding the potential efficacy and safety benefits, as well as the challenges, of incorporating our product candidates, if approved, into treatment regimens; and

    establishing the sales and marketing capabilities to gain market acceptance, if approved.

If serious adverse or unacceptable side effects are identified during the development of our product candidates or we observe limited efficacy of our product candidates, we may need to abandon or limit the development of one or more of our product candidates.

        Adverse events or unacceptable side effects caused by, or other unexpected properties of, our product candidates could cause us, any future collaborators, an institutional review board, or IRB, or regulatory authorities to interrupt, delay or halt clinical trials of one or more of our product candidates and could result in the (i) delay or denial of marketing approval by the FDA or comparable foreign regulatory authorities, (ii) approval with significant restrictions on distribution or (iii) required labeling information regarding safety concerns, if approved.

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        In general, our clinical trials of APR-246 include cancer patients who are very sick and whose health is deteriorating, and we expect that additional clinical trials of APR-246 and our other product candidates will include similar patients with deteriorating health. Multiple patients in our trials have experienced adverse events, including serious adverse events. The most commonly reported adverse events include nausea, vomiting, constipation, dizziness and neutropenia. Some patients in our trials have experienced serious adverse events. See "Business—Our Approach." In the U.S. Phase 1b/2 MDS/AML Trial, serious adverse events, regardless of causality, reported for more than one patient were: febrile neutropenia (27%), lung infection (9%), infections and infestations (5%), respiratory failure (5%), sepsis (5%), vomiting (5%), chest pain (4%), dehydration (4%), intracranial hemorrhage (4%) and multi-organ failure (4%). In the Phase 1b/2 Clinical Trial of APR 246 in Platinum Sensitive Ovarian Cancer (PiSARRO), serious adverse events, regardless of causality, reported in more than one patient were: device related infection (17%), vomiting (17%), febrile neutropenia (8%), infection (6%), small intestinal obstruction (6%) and thrombocytopenia (6%).

        Some patients have died during their participation in the clinical trials for APR-246, and there has been one death reported by an investigator as possibly related to both APR-246 and azacitidine. We believe this death may have been caused by the underlying disease, other comorbidities from which such patient was suffering or the other co-administered treatments. Any deaths occurring in our clinical trials, whether related to our product candidate or not, could affect perceptions relating to our product candidate.

        If any of our product candidates are associated with adverse events or undesirable side effects or have properties that are unexpected, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of or deny approval of our product candidates for any or all targeted indications. We, or any future collaborators, may abandon development or limit development of that product candidate to certain uses or subpopulations in which the undesirable side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. Drug-related side effects could affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, results of operations, financial condition and prospects significantly.

The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, interim results of a clinical trial do not necessarily predict final results, and the results of our clinical trials may not satisfy the requirements of the FDA or comparable foreign regulatory authorities.

        We currently have no drugs approved for sale and we cannot guarantee that we will ever have marketable drugs. Clinical failure can occur at any stage of clinical development. Clinical trials may produce negative or inconclusive results, and we or any future collaborators may decide, or regulators may require us, to conduct additional clinical trials or preclinical studies. We will be required to demonstrate with substantial evidence through adequate and well-controlled clinical trials that our product candidates are safe and effective for use in treating specific conditions in order to obtain marketing approvals for their commercial sale. Success in preclinical studies and early-stage clinical trials does not mean that future larger registration clinical trials will be successful because product candidates in later-stage clinical trials may fail to demonstrate safety and efficacy to the satisfaction of the FDA and non-U.S. regulatory authorities despite having progressed through preclinical studies and early-stage clinical trials. Product candidates that have shown promising results in preclinical studies and early-stage clinical trials may still suffer significant setbacks in subsequent registration clinical trials. Additionally, the outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later-stage clinical trials.

        From time to time, we may publish or report interim or preliminary data from our clinical trials. Interim or preliminary data from clinical trials that we may conduct may not be indicative of the final

18


results of the trial and are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Interim or preliminary data also remain subject to audit and verification procedures that may result in the final data being materially different from the interim or preliminary data. As a result, interim or preliminary data should be viewed with caution until the final data are available.

        In addition, the design of a clinical trial can determine whether its results will support approval of a drug and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. We have limited experience in designing clinical trials and may be unable to design and conduct a clinical trial to support marketing approval. Further, if our product candidates are found to be unsafe or lack efficacy, we will not be able to obtain marketing approval for them and our business would be harmed. A number of companies in the pharmaceutical industry, including those with greater resources and experience than us, have suffered significant setbacks in advanced clinical trials, even after obtaining promising results in preclinical studies and earlier clinical trials.

        In some instances, there can be significant variability in safety and efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in trial protocols, differences in size and type of the patient populations, differences in and adherence to the dosing regimen and other trial protocols and the rate of dropout among clinical trial participants. We do not know whether any clinical trials we may conduct will demonstrate consistent or adequate efficacy and safety sufficient to obtain marketing approval to market our product candidates.

        We have multiple clinical trials of APR-246 currently ongoing. In the event that an adverse safety issue, clinical hold or other adverse finding occurs in one or more of our clinical trials of APR-246, such event could adversely affect our other clinical trials of APR-246. Moreover, there is a relatively limited safety data set for product candidates that are designed to reactivate p53. An adverse safety issue or other adverse finding in a clinical trial conducted by a third party with a product candidate reactivate p53, could adversely affect our clinical trials of APR-246.

        Further, our product candidates may not be approved even if they achieve their primary endpoints in Phase 3 clinical trials or registration trials. The FDA or non-U.S. regulatory authorities may disagree with our trial design and our interpretation of data from preclinical studies and clinical trials. In addition, any of these regulatory authorities may change requirements for the approval of a product candidate even after reviewing and providing comments or advice on a protocol for a pivotal clinical trial that has the potential to result in approval by the FDA or another regulatory authority. In addition, any of these regulatory authorities may also approve a product candidate for fewer or more limited indications than we request or may grant approval contingent on the performance of costly post-marketing clinical trials. In addition, the FDA or other comparable foreign regulatory authorities may not approve the labeling claims that we believe would be necessary or desirable for the successful commercialization of our product candidates.

        Before obtaining marketing approvals for the commercial sale of any product candidate for a target indication, we must demonstrate with substantial evidence gathered in preclinical studies and adequate and well-controlled clinical trials, and, with respect to approval in the United States, to the satisfaction of the FDA and other comparable foreign regulatory authorities, that the product candidate is safe and effective for use for that target indication. There is no assurance that the FDA or other comparable foreign regulatory authorities will consider our future clinical trials to be sufficient to serve as the basis for approval of one of our product candidates for any indication. The FDA and other comparable foreign regulatory authorities retain broad discretion in evaluating the results of our clinical trials and in determining whether the results demonstrate that a product candidate is safe and effective. If we are required to conduct additional clinical trials of a product candidate than we expect prior to its approval, we will need substantial additional funds and there is no assurance that the results of any such additional clinical trials will be sufficient for approval.

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Clinical drug development is a lengthy and expensive process, with an uncertain outcome. If clinical trials of our product candidates fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs, experience delays in completing, or ultimately be unable to complete, the development of our product candidates or be unable to obtain marketing approval.

        Before obtaining marketing approval from regulatory authorities for the sale of our product candidates, we must complete preclinical development and then conduct extensive clinical trials to demonstrate the safety and efficacy of our product candidates. Clinical testing is expensive, difficult to design and implement, can take many years to complete and is uncertain as to outcome. A failure of one or more clinical trials can occur at any stage of testing. The outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial, such as the results of our ongoing clinical trials of APR-246, do not necessarily predict final results. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their drugs.

        We do not know whether ongoing clinical trials will be completed on schedule or at all, or whether future clinical trials will begin on time, need to be redesigned, enroll patients on time or be completed on schedule, if at all. Clinical trials can be delayed for a variety of reasons, including delays related to:

    obtaining regulatory authorization to commence a trial;

    reaching agreement on acceptable terms with prospective contract research organizations, or CROs, and clinical trial sites, the terms of which can be subject to extensive negotiation and may vary significantly among different CROs and clinical trial sites;

    obtaining institutional review board or ethics committee approval at each clinical trial site;

    recruiting suitable patients to participate in a trial;

    developing and validating any companion diagnostic to be used in the trial, to the extent we are required to do so;

    patients failing to comply with the clinical trial protocol or dropping out of a trial;

    clinical trial sites failing to comply with the clinical trial protocol or dropping out of a trial;

    addressing any conflicts with new or existing laws or regulations;

    the need to add new clinical trial sites;

    manufacturing sufficient quantities of product candidate for use in clinical trials and ensuring clinical trial material is provided to clinical sites in a timely manner; or

    obtaining advice from regulatory authorities regarding the statistical analysis plan to be used to evaluate the clinical trial data or other trial design issues.

        We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval or commercialize our product candidates, including:

    we may receive feedback from regulatory authorities that requires us to modify the design of our clinical trials;

    clinical trials of our product candidates may produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or abandon drug development programs;

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    the number of patients required for clinical trials of our product candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate or participants may drop out of these clinical trials at a higher rate than we anticipate;

    our third-party contractors, including our CROs, may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

    we, our investigators, or any of the overseeing IRBs or ethics committees might decide to suspend or terminate clinical trials of our product candidates for various reasons, including non-compliance with regulatory requirements, a finding that our product candidates have undesirable side effects or other unexpected characteristics, or a finding that the participants are being exposed to unacceptable health risks;

    the cost of clinical trials of our product candidates may be greater than we anticipate;

    the supply or quality of our product candidates or other materials necessary to conduct clinical trials of our product candidates may be insufficient or inadequate;

    regulators may revise the requirements for approving our product candidates, or such requirements may not be as we anticipate; and

    any future collaborators that conduct clinical trials may face any of the above issues, and may conduct clinical trials in ways they view as advantageous to them but that are suboptimal for us.

        If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are insufficiently positive to support marketing approval, or if there are safety concerns, we may:

    incur unplanned costs;

    be delayed in obtaining marketing approval for our product candidates or not obtain marketing approval at all;

    obtain marketing approval in some countries and not in others;

    obtain marketing approval for indications or patient populations that are narrower or more limited in scope than intended or desired;

    obtain marketing approval subject to significant use or distribution restrictions or with labeling that includes significant safety warnings, including boxed warnings;

    be subject to additional post-marketing testing requirements; or

    have the drug removed from the market after obtaining marketing approval.

        Our drug development costs will also increase if we experience delays in testing or marketing approvals. We do not know whether clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Furthermore, we rely on third-party CROs and clinical trial sites to ensure the proper and timely conduct of our clinical trials, and while we have agreements governing their committed activities, we have limited influence over their actual performance. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring drugs to market before we do and impair our ability to successfully commercialize our product candidates and may harm our business and results of operations.

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We may expend our limited resources to pursue a particular product candidate or indication and fail to capitalize on product candidates or indications that may be more profitable or for which there is a greater likelihood of success.

        Because we have limited financial and managerial resources, we focus on research programs and product candidates that we identify for specific indications. As a result, we may forego or delay pursuit of opportunities with other product candidates or for other indications that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial drugs or profitable market opportunities. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable drugs. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other strategic arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

The failure to obtain required regulatory clearances or approvals for any companion diagnostic tests that we may pursue may prevent or delay approval of any of our product candidates. Moreover, the commercial success of any of our product candidates that require a companion diagnostic will be tied to the receipt of any required regulatory clearances or approvals and the continued availability of such tests.

        In connection with the clinical development of our product candidates for certain indications, we may work with collaborators to develop or obtain access to companion diagnostic tests to identify appropriate patients for our product candidates. We may rely on third parties for the development, testing and manufacturing of these companion diagnostics, the application for and receipt of any required regulatory clearances or approvals, and the commercial supply of these companion diagnostics. The FDA and foreign regulatory authorities regulate companion diagnostics as medical devices that will likely be subject to clinical trials in conjunction with the clinical trials for product candidates, and which will require separate regulatory clearance or approval prior to commercialization. This process could include additional meetings with health authorities, such as a pre-submission meeting and the requirement to submit an investigational device exemption. In the case of a companion diagnostic that is designated as "significant risk device," approval of an investigational device exemption by the FDA and IRB is required before such diagnostic is used in conjunction with the clinical trials for a corresponding product candidate. We or our third-party collaborators may fail to obtain the required regulatory clearances or approvals, which could prevent or delay approval of our product candidates. In addition, the commercial success of any of our product candidates that require a companion diagnostic will be tied to and dependent upon the receipt of required regulatory clearances or approvals and the continued ability of such third parties to make the companion diagnostic commercially available to us on reasonable terms in the relevant geographies.

We may not be successful in our efforts to identify or discover additional potential product candidates.

        Our research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development for a number of reasons, including:

    the research methodology used may not be successful in identifying potential product candidates;

    potential product candidates may, on further study, be shown to have harmful side effects or other characteristics that indicate that they are unlikely to be drugs that will receive marketing approval and/or achieve market acceptance; and

    potential product candidates may not be safe or effective in treating their targeted diseases.

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        Research programs to identify new product candidates require substantial technical, financial and human resources. If we are unable to identify suitable compounds for preclinical and clinical development, our business would be harmed.

If any of our product candidates receives marketing approval and we, or others, later discover that the drug is less effective than previously believed or causes undesirable side effects that were not previously identified, our ability, or that of any future collaborators, to market the drug could be compromised.

        Clinical trials of our product candidates must be conducted in carefully defined subsets of patients who have agreed to enter into clinical trials. Consequently, it is possible that our clinical trials, or those of any future collaborator, may indicate an apparent positive effect of a product candidate that is greater than the actual positive effect, if any, or alternatively fail to identify undesirable side effects. If one or more of our product candidates receives marketing approval and we, or others, discover that the drug is less effective than previously believed or causes undesirable side effects that were not previously identified, a number of potentially significant negative consequences could result, including:

    regulatory authorities may withdraw their approval of the drug or seize the drug;

    we, or any future collaborators, may be required to recall the drug, change the way the drug is administered or conduct additional clinical trials;

    additional restrictions may be imposed on the marketing of, or the manufacturing processes for, the particular drug;

    we may be subject to fines, injunctions or the imposition of civil or criminal penalties;

    regulatory authorities may require the addition of labeling statements, such as a "black box" warning or a contraindication;

    we, or any future collaborators, may be required to create a Medication Guide outlining the risks of the previously unidentified side effects for distribution to patients;

    we, or any future collaborators, could be sued and held liable for harm caused to patients;

    the drug may become less competitive in the marketplace; and

    our reputation may suffer.

        Any of these events could have a material and adverse effect on our operations and business and could adversely impact our stock price.

Even if any of our product candidates receive marketing approval, they may fail to achieve the degree of market acceptance by physicians, patients, healthcare payors and others in the medical community necessary for commercial success.

        If any of our product candidates receive marketing approval, they may nonetheless fail to gain sufficient market acceptance by physicians, patients, healthcare payors and others in the medical community. For example, current cancer treatments like chemotherapy and radiation therapy are well-established in the medical community, and doctors may continue to rely on these treatments. If our product candidates do not achieve an adequate level of acceptance, we may not generate significant revenues from sales of drugs and we may not become profitable. The degree of market acceptance of our product candidates, if approved for commercial sale, will depend on a number of factors, including:

    the efficacy and safety of the product;

    the potential advantages of the product compared to alternative therapies;

    the prevalence and severity of any side effects;

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    whether the product is designated under physician and other provider treatment guidelines as a first-, second- or third-line therapy;

    our ability, or the ability of any future collaborators, to offer the product for sale at competitive prices;

    the product's convenience and ease of administration for patients and healthcare practitioners compared to alternative treatments;

    the willingness of the target patient population to try, and of physicians to prescribe, the product;

    limitations or warnings, including distribution or use restrictions and safety information contained in the product's approved labeling;

    the strength of sales, marketing and distribution support;

    changes in the standard of care for the targeted indications for the product; and

    the availability of coverage by, and the amount of reimbursement from, government payors, managed care plans and other third-party payors.

We face substantial competition, which may result in others discovering, developing or commercializing products before or more successfully than we do.

        The pharmaceutical and biotechnology industries generally, and the cancer drug sector specifically, are highly competitive and characterized by rapidly advancing technologies, evolving understanding of disease etiology and a strong emphasis on proprietary drugs. We face competition with respect to APR-246, our lead product candidate, and will face competition with respect to any product candidates that we may seek to discover and develop or commercialize in the future, from major pharmaceutical, specialty pharmaceutical and biotechnology companies. There are a number of major pharmaceutical, specialty pharmaceutical and biotechnology companies that currently market and sell drugs or are pursuing the development of drugs for the treatment of cancer. Potential competitors also include academic institutions and governmental agencies and public and private research institutions.

        There are a large number of companies developing or marketing treatments for cancer, including the indications for which we may develop product candidates. Many of the companies that we compete or may compete against in the future have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and marketing approved drugs than we do. Small or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These competitors also compete with us in recruiting and retaining qualified scientific and management personnel and establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or that may be necessary for, our programs.

        Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize drugs that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than any drugs that we may develop. Our competitors also may obtain FDA or other regulatory approval for their drugs more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market. The key competitive factors affecting the success of all of our product candidates, if approved, are likely to be their efficacy, safety, convenience, price, the effectiveness of companion diagnostics in guiding the use of related therapeutics, the level of generic competition and the availability of reimbursement from government and other third-party payors.

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        The most common methods of treating patients with cancer are surgery, radiation and drug therapy. There are a variety of available drug therapies marketed for cancer. In many cases, these drugs are administered in combination to enhance efficacy. Some of the currently-approved drug therapies are branded and subject to patent protection and may be established as the standard of care for treatment of indications for which we may choose to seek regulatory approvals. Many of these approved drugs are well-established therapies and are widely accepted by physicians, patients and third-party payors, and, even if our product candidates were to be approved, there can be no assurance that our product candidates would displace existing treatments. In addition to currently marketed therapies, there are also a number of drugs in late-stage clinical development to treat cancer, including the indications for which we are developing product candidates. These clinical-stage product candidates may provide efficacy, safety, convenience and other benefits that are not provided by currently-marketed therapies. As a result, they may provide significant competition for any of our product candidates for which we obtain regulatory approval.

        We are developing our lead product candidate, APR-246, to reactivate p53 for the treatment of various cancers. We are aware of other product candidates that are in clinical development for the treatment of various cancers through the reactivation of p53. Although there is a subset of drugs that directly target the p53 pathway, there are many cancer drugs that claim to affect the p53 pathway by upstream or complementary pathways. We are aware of selective small molecule inhibitors that are designed to target the p53-MDM2 interaction in various stages of clinical development being tested by F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc., or collectively Roche, Amgen Inc., Novartis AG, Daiichi Sankyo Co., Ltd, and Aileron Therapeutics, Inc. If APR-246 were to be approved for the indications for which we currently have ongoing clinical trials, it will compete with currently-marketed drugs or drugs that may be approved for marketing by the FDA or comparable foreign regulatory authorities in the future and such competition will not be limited to drugs that act through the reactivation of p53.

Our business and operations would suffer in the event of IT system failures, cybersecurity attacks, data breaches, or vulnerabilities in our or our third-party vendors' information security program or defenses.

        Our business relies upon information technology systems operated by us and by our third party service providers. These systems may fail or experience operational disruption, experience cybersecurity attacks, or be damaged by computer viruses and unauthorized access. In the ordinary course of business, we collect, store and transmit confidential information (including but not limited to intellectual property, proprietary business information and personal information). It is critical that we do so in a secure manner to maintain the confidentiality and integrity of such confidential information. While we are currently in the process of developing and implementing policies and procedures to ensure the security and integrity of our information technology systems and confidential and proprietary information, we do not currently have any such policies and procedures formally in place. If we fail to develop and maintain adequate policies and procedures for the protection of our information technology systems and confidential and proprietary information, we may be vulnerable to security breaches or disruptions and system breakdowns or other damage or interruptions. We also have outsourced elements of our operations to third parties, and as a result we manage a number of third-party vendors and other contractors and consultants who have access to or store our confidential information. We do not conduct audits or formal evaluations of our third-party vendors' information technology systems and cannot be sure that our third-party vendors have sufficient measures in place to ensure the security and integrity of their information technology systems and our confidential and proprietary information. If our third-party vendors fail to protect their information technology systems and our confidential and proprietary information, we may be vulnerable to disruptions in service and unauthorized access to our confidential or proprietary information and we could incur liability and reputational damage and the further development and commercialization of our product candidates could be delayed. While we have not, to our knowledge, experienced any material IT system failures or

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cybersecurity attacks to date, we cannot assure you that our data protection efforts and our investment in information technology will prevent significant breakdowns, data leakages, breaches in our systems or those of our third-party vendors and other contractors and consultants, or other cyber incidents that could have a material adverse effect upon our reputation, business, operations or financial condition. If such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our development programs, business operations, a breach of sensitive personal information or a loss or corruption of critical data assets including trade secrets or other proprietary information. For example, the loss of clinical trial data from future clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. Such IT system failures, cybersecurity attacks or vulnerabilities to our or our third-party vendors' information security programs or defenses could result in legal liability, reputational damage, business interruption, and our competitive position could be harmed and the further development and commercialization of our products or any future products could be delayed or disrupted. Moreover, containing and remediating any IT system failure, cybersecurity attack or vulnerability may require significant investment of resources. Furthermore, significant security breaches or disruptions of our internal information technology systems or those of our third-party vendors and other contractors and consultants could result in the loss, misappropriation and/or unauthorized access, use, or disclosure of, or the prevention of access to, confidential information (including trade secrets or other intellectual property, proprietary business information and personal information), which could result in financial, legal, business and reputational harm to us.

If we are required to in the future and if we are unable to successfully develop companion diagnostic tests for our product candidates that require such tests, or experience significant delays in doing so, we may not realize the full commercial potential of these product candidates.

        We may be required by the FDA to develop, either by ourselves or with collaborators, companion diagnostic tests for our product candidates for certain indications. To be successful, we or our collaborators will need to address a number of scientific, technical, regulatory and logistical challenges. We have no prior experience with medical device or diagnostic test development. If we choose to develop and seek FDA approval for companion diagnostic tests on our own, we will require additional personnel. We may rely on third parties for the design, development and manufacture of companion diagnostic tests for our therapeutic product candidates that require such tests. If these parties are unable to successfully develop companion diagnostics for these therapeutic product candidates, or experience delays in doing so, we may be unable to enroll enough patients for our current and planned clinical trials, the development of these therapeutic product candidates may be adversely affected, these therapeutic product candidates may not obtain marketing approval, and we may not realize the full commercial potential of any of these therapeutics that obtain marketing approval. Any failure to successfully develop this companion diagnostic may cause or contribute to delayed enrollment of this trial, and may prevent us from initiating or completing further clinical trials to support marketing approval for our product candidates. As a result, our business, results of operations and financial condition could be materially harmed.

If, in the future, we are unable to establish sales and marketing capabilities or enter into agreements with third parties to sell and market our product candidates, we may not be successful in commercializing our product candidates if and when they are approved.

        We do not have a sales or marketing infrastructure and have no experience in the sale or marketing of pharmaceutical drugs. We are not currently a party to a strategic collaboration that provides us with access to a collaborator's resources in selling or marketing drugs. To achieve commercial success for any approved drug for which sales and marketing is not the responsibility of any strategic collaborator that we may have in the future, we must either develop a sales and marketing organization or outsource these functions to other third parties. In the future, we may choose to build

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a sales and marketing infrastructure to market or co-promote some of our product candidates if and when they are approved, or enter into collaborations with respect to the sale and marketing of our product candidates.

        There are risks involved with both establishing our own sales and marketing capabilities and entering into arrangements with third parties to perform these services. For example, recruiting and training a sales force is expensive and time-consuming and could delay any commercial launch of a product candidate. If the commercial launch of a product candidate for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

        Factors that may inhibit our efforts to commercialize our product candidates on our own include:

    our inability to recruit and retain adequate numbers of effective sales and marketing personnel;

    limitations or restrictions on the ability of sales personnel to appropriately market the product to physicians or other healthcare professionals;

    the lack of complementary drugs to be offered by sales personnel, which may put us at a competitive disadvantage relative to companies with more extensive product lines;

    unforeseen costs and expenses associated with creating an independent sales and marketing organization; and

    inability to obtain sufficient coverage and reimbursement from third-party payors and governmental agencies.

        If we enter into arrangements with third parties to perform sales and marketing services, our revenues from the sale of drugs or the profitability of these revenues to us are likely to be lower than if we were to market and sell any drugs that we develop ourselves. In addition, we may not be successful in entering into arrangements with third parties to sell and market our product candidates or may be unable to do so on terms that are favorable to us. We likely will have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market our product candidates effectively. If we do not establish sales and marketing capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our product candidates.

If the FDA or comparable foreign regulatory authorities approve generic versions of any of our product candidates that receive marketing approval, or such authorities do not grant our product candidates appropriate periods of data or market exclusivity before approving generic versions of our product candidates, the sales of our product candidates could be adversely affected.

        Once an NDA is approved, the drug covered thereby becomes a "reference-listed drug" in the FDA's publication, "Approved Drug Products with Therapeutic Equivalence Evaluations." Manufacturers may seek marketing approval of generic versions of reference-listed drugs through submission of abbreviated new drug applications, or ANDAs, in the United States. In support of an ANDA, a generic manufacturer need not conduct clinical trials demonstrating safety and efficacy. Rather, the applicant generally must show that its drug is pharmaceutically equivalent to the reference listed drug, in that it has the same active ingredient(s), dosage form, strength, route of administration and conditions of use or labeling as the reference-listed drug, and that the generic version is bioequivalent to the reference-listed drug, meaning it is absorbed in the body at the same rate and to the same extent. Generic drugs may be significantly less costly to bring to market than the reference-listed drug and companies that produce generic drugs are generally able to offer them at lower prices.

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Thus, following the introduction of a generic drug, a significant percentage of the sales of any branded product or reference-listed drug is typically lost to the generic drug.

        The FDA may not approve an ANDA for a generic drug until any applicable period of non-patent exclusivity for the reference-listed drug has expired. The Federal Food, Drug, and Cosmetic Act, or FDCA, provides a period of five years of non-patent exclusivity for a new drug containing a new chemical entity, or NCE. During the exclusivity period, the FDA may not accept for review an ANDA or a 505(b)(2) NDA submitted by another company for another version of such product candidate where the applicant does not own or have a legal right of reference to all the data required for approval. However, an application may be submitted after four years if it contains a certification of patent invalidity or non-infringement. The FDCA also provides three years of marketing exclusivity for an NDA, 505(b)(2) NDA or supplement to an approved NDA if new clinical investigations, other than bioavailability studies, that were conducted or sponsored by the applicant are deemed by the FDA to be essential to the approval of the application, for example, for new indications, dosages or strengths of an existing product candidate. This three-year exclusivity covers only the conditions associated with the new clinical investigations and does not prohibit the FDA from approving ANDAs for product candidates containing the original active agent. Five-year and three-year exclusivity will not delay the submission or approval of a full NDA. However, an applicant submitting a full NDA would be required to conduct or obtain a right of reference to all of the nonclinical studies and adequate and well-controlled clinical trials necessary to demonstrate safety and effectiveness. Manufacturers may seek to launch these generic drugs following the expiration of the marketing exclusivity period, even if we still have patent protection for our drug.

        Competition that our product candidates may face from generic versions of our product candidates could materially and adversely impact our future revenue, profitability and cash flows and substantially limit our ability to obtain a return on the investments we have made in those product candidates. Our future revenues, profitability and cash flows could also be materially and adversely affected and our ability to obtain a return on the investments we have made in those product candidates may be substantially limited if our product candidates, if and when approved, are not afforded the appropriate periods of non-patent exclusivity.

Even if we obtain regulatory approval of any product candidate, the approved product may be subject to post-approval studies and will remain subject to ongoing regulatory requirements. If we fail to comply, or if concerns are identified in subsequent studies, our approval could be withdrawn, and our product sales could be suspended.

        If we are successful at obtaining regulatory approval for APR-246 or any of our other product candidates, regulatory agencies in the United States and other countries where a product will be sold may require extensive additional clinical trials or post-approval clinical trials that are expensive and time-consuming to conduct. These trials may reveal side effects or other harmful effects in patients that use our products after they are on the market, which may result in the limitation or withdrawal of our drugs from the market. Alternatively, we may not be able to conduct such additional trials, which might force us to abandon our efforts to develop or commercialize certain product candidates. Even if post-approval studies are not requested or required, after our products are approved and on the market, there might be safety issues that emerge over time that require a change in product labeling, additional postmarket studies or clinical trials, imposition of distribution and use restrictions under a Risk Evaluation and Mitigation Strategy, or REMS, or withdrawal of the product from the market, which would cause our revenue to decline.

        Additionally, any products that we may successfully develop will be subject to ongoing regulatory requirements after they are approved. These requirements will govern the manufacturing, packaging, marketing, distribution, and use of our products. If we fail to comply with such regulatory requirements, approval for our products may be withdrawn, and product sales may be suspended. We

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may not be able to regain compliance, or we may only be able to regain compliance after a lengthy delay, significant expense, lost revenues and damage to our reputation.

Even if we are able to commercialize any product candidate, such product candidate may become subject to unfavorable pricing regulations, third-party coverage and reimbursement policies or healthcare reform initiatives, which could harm our business.

        The regulations that govern marketing approval, pricing, coverage and reimbursement for new drugs vary widely from country to country. Some countries require approval of the sale price of a drug before it can be marketed. In many countries, the pricing review period begins after marketing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control even after initial approval is granted. As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, and negatively impact the revenues we are able to generate from the sale of the product in that country. Adverse pricing limitations may hinder our ability to recoup our investment in one or more product candidates, even if our product candidates obtain marketing approval.

        Our ability to commercialize any products successfully also will depend in part on the extent to which reimbursement and coverage for these products and related treatments will be available from government authorities, private health insurers and other organizations, and if reimbursement and coverage is available, the level of reimbursement and coverage. Government authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels. A primary trend in the healthcare industry in the United States and elsewhere is cost containment. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. Increasingly, the third-party payors who reimburse patients or healthcare providers, such as government and private insurance plans, are requiring that drug companies provide them with predetermined discounts from list prices, and are seeking to reduce the prices charged or the amounts reimbursed for medical products. We cannot be sure that coverage and reimbursement will be available for any drug that we commercialize and, if coverage and reimbursement are available, we cannot be sure as to the level of reimbursement. Reimbursement may impact the demand for, or the price of, any product candidate for which we obtain marketing approval. If reimbursement is not available or is available only to limited levels, we may not be able to successfully commercialize any product candidate for which we obtain marketing approval.

        There may be significant delays in obtaining reimbursement for newly approved drugs, and coverage may be more limited than the purposes for which the drug is approved by the FDA or comparable foreign regulatory authorities. Moreover, eligibility for reimbursement does not imply that any drug will be reimbursed in all cases or at a rate that covers our costs, including research, development, manufacture, sale and distribution. Interim reimbursement levels for new drugs, if applicable, may also not be sufficient to cover our costs and may not be made permanent. Reimbursement rates may vary according to the use of the drug and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost drugs, may be incorporated into existing payments for other items or services and may reflect budgetary constraints or imperfections in Medicare data. Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the United States. Third-party payors often rely upon Medicare coverage policy and payment limitations in setting their own reimbursement rates. Our inability to promptly obtain coverage and adequate reimbursement rates from both government-funded and private payors for new products that we develop and for which we obtain marketing approval could have a material adverse effect on our operating results, our ability to raise capital needed to commercialize products and our overall financial condition.

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Product liability lawsuits against us could cause us to incur substantial liabilities and to limit commercialization of any drugs that we may develop. Our insurance policies may be inadequate and may potentially expose us to unrecoverable risk.

        We face an inherent risk of product liability exposure related to the testing of our product candidates in clinical trials and will face an even greater risk if we commercially sell any drugs that we may develop. If we cannot successfully defend ourselves against claims that our product candidates or drugs caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

    decreased demand for any product candidates or drugs that we may develop;

    injury to our reputation and significant negative media attention;

    withdrawal of clinical trial participants;

    significant costs to defend the related litigation;

    substantial monetary awards to trial participants or patients;

    loss of revenue;

    reduced resources of our management to pursue our business strategy; and

    the inability to commercialize any drugs that we may develop.

        We currently hold clinical trial liability insurance coverage for up to $3.0 million, but that coverage may not be adequate to cover any and all liabilities that we may incur. We would need to increase our insurance coverage when we begin the commercialization of our product candidates, if ever. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise.

Governments outside of the United States tend to impose strict price controls, which may adversely affect our revenues from the sales of our products, if any.

        In some countries, particularly member states of the European Union, or, the EU, the pricing of prescription pharmaceuticals is subject to governmental control. In these countries, pricing negotiations with governmental authorities can take considerable time after the receipt of marketing approval for a product. In addition, there can be considerable pressure by governments and other stakeholders on prices and reimbursement levels, including as part of cost containment measures. Political, economic and regulatory developments may further complicate pricing negotiations, and pricing negotiations may continue after reimbursement has been obtained. Reference pricing used by various EU member states and parallel distribution, or arbitrage between low-priced and high-priced member states, can further reduce prices. In some countries, we, or our future collaborators, may be required to conduct a clinical trial or other studies that compare the cost-effectiveness of our product candidates to other available therapies in order to obtain or maintain reimbursement or pricing approval. Publication of discounts by third-party payors or authorities may lead to further pressure on the prices or reimbursement levels within the country of publication and other countries. If reimbursement of any product candidate approved for marketing is unavailable or limited in scope or amount, or if pricing is set at unsatisfactory levels, our business could be materially harmed.

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Risks related to our dependence on third parties

We rely on third parties to conduct our clinical trials and some aspects of our research and preclinical studies, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials, research and studies.

        We currently rely on third parties, such as CROs, clinical data management organizations, medical institutions and clinical investigators, to conduct our clinical trials of APR-246 and expect to continue to rely upon third parties to conduct additional clinical trials of APR-246 and our other product candidates. We currently rely and expect to continue to rely on third parties to conduct some aspects of our research and preclinical studies. Any of these third parties may terminate their engagements with us at any time. If we need to enter into alternative arrangements, it would delay our drug development activities.

        Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our regulatory responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan, study protocols for the trial, statistical analysis plan and other study-specific documents (for example, monitoring and blinding plans). Moreover, the FDA requires us to comply with standards, commonly referred to as Good Clinical Practice, or GCP, International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, or ICH, guidelines, and regulations regarding the informed consent process, safety reporting requirements, data collection guidelines, and other regulations for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. The European Medicines Agency, or EMA, also requires us to comply with similar standards. Regulatory authorities enforce these GCP requirements through periodic inspections of trial sponsors, principal investigators and trial sites. If we or any of our CROs fail to comply with applicable GCP requirements, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, EMA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP and other applicable regulations. In addition, our clinical trials must be conducted with product produced under current Good Manufacturing Practices, or cGMP, regulations. Our failure to comply with these regulations may require us to conduct new clinical trials, which would delay the marketing approval process. We also are required to register certain ongoing clinical trials and post the results of certain completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within certain timeframes. Failure to do so can result in fines, adverse publicity and civil and criminal sanctions.

        Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. If these third parties do not successfully carry out their contractual duties, meet expected deadlines or conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we will not be able to obtain, or may be delayed in obtaining, marketing approvals for our product candidates and will not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates.

        We also expect to rely on other third parties to store and distribute drug supplies for our clinical trials. Any performance failure on the part of such third parties could delay clinical development or marketing approval of our product candidates or commercialization of our product candidates, producing additional losses and depriving us of potential revenue from sales of drugs.

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We are currently dependent on a single third party manufacturer for the manufacture of the active pharmaceutical ingredient for APR-246. This reliance on a single third party increases the risk that we will not have sufficient quantities of our product candidates or drugs or such quantities at an acceptable cost, which could delay, prevent or impair our development or commercialization efforts.

        We do not have any manufacturing facilities or personnel, and we currently have no plans to build our own clinical or commercial scale manufacturing capabilities. We currently contract with third parties for the manufacture of our product candidates for certain preclinical trials and clinical trial materials, including raw materials and consumables necessary for their manufacture, consistent with applicable cGMP requirements. We intend to continue to contract for these materials in the future, including commercial manufacture if our product candidates receive marketing approval.

        The active pharmaceutical ingredient, or API, for APR-246 is currently manufactured by a single contract manufacturer. Although we may do so in the future, we do not currently have arrangements in place for redundant supply of the API for APR-246. We contract with a different manufacturer for formulation of drug product, sterile fill of vials, labeling and packaging, and the storage and distribution of APR-246 to clinical sites.

        We expect to rely on third-party manufacturers or third-party collaborators for the manufacture of our product candidates for commercial supply of any of our product candidates for which we or any of our future collaborators obtain marketing approval. We may be unable to establish any agreements with third-party manufacturers or to do so on acceptable terms. Even if we are able to establish agreements with third-party manufacturers, reliance on third-party manufacturers entails additional risks, including:

    the possible failure of the third party to manufacture our product candidate according to our schedule, or at all, including if our third-party contractors give greater priority to the supply of other products over our product candidates or otherwise do not satisfactorily perform according to the terms of the agreements between us and them;

    the possible termination or nonrenewal of agreements by our third-party contractors at a time that is costly or inconvenient for us;

    the possible breach by the third-party contractors of our agreements with them;

    the failure of third-party contractors to comply with applicable regulatory requirements;

    the possible failure of the third party to manufacture our product candidates according to our specifications;

    the possible mislabeling of clinical supplies, potentially resulting in issues including the wrong dose amounts being supplied or active drug or placebo not being properly identified;

    the possibility of clinical supplies not being delivered to clinical sites on time, leading to clinical trial interruptions, or of drug supplies not being distributed to commercial vendors in a timely manner, resulting in lost sales; and

    the possible misappropriation of our proprietary information, including our trade secrets and know-how.

        The facilities used by our contract manufacturers to manufacture our product candidates must be approved by the FDA or the EMA pursuant to inspections that will be conducted after we submit our NDA to the FDA or our MAA to the EMA. We do not have complete control over all aspects of the manufacturing process of, and are dependent on, our contract manufacturing partners for compliance with cGMP regulations for manufacturing both active drug substances and finished drug products. Third-party manufacturers may not be able to comply with cGMP regulations or similar regulatory requirements outside of the United States. If our contract manufacturers cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the

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FDA or other regulatory bodies, they will not be able to secure and/or maintain marketing approval for their manufacturing facilities. In addition, we do not have complete control over the ability of our contract manufacturers to maintain adequate quality control, quality assurance and qualified personnel. If the FDA, the EMA or a comparable foreign regulatory authority does not approve these facilities for the manufacture of our product candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would significantly impact our ability to develop, obtain marketing approval for or market our product candidates, if approved.

        Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of product candidates or drugs, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supplies of our product candidates and harm our business and results of operations.

        Any drugs that we may develop may compete with other product candidates and drugs for access to manufacturing facilities. There are a limited number of manufacturers that operate under cGMP regulations and that might be capable of manufacturing for us.

        Any performance failure on the part of our existing or future manufacturers could delay clinical development or marketing approval.

        We do not currently have arrangements in place for redundant supply of the API of APR-246. If our current contract manufacturer cannot perform as agreed, we may be required to replace that manufacturer. Although we believe that there are several potential alternative manufacturers who could manufacture our product candidates, we may incur added costs and delays in identifying and qualifying any such replacement.

        Our current and anticipated future dependence upon others for the manufacture of our product candidates or drugs may adversely affect our future profit margins and our ability to commercialize any drugs that receive marketing approval on a timely and competitive basis.

Although we currently plan to retain all commercial rights to APR-246 and our product candidates, we may enter into strategic collaborations for the development, marketing and commercialization of APR-246 and our other product candidates. If those collaborations are not successful, the development, marketing and/or commercialization of our product candidates that are the subject of such collaborations would be harmed.

        As we further develop APR-246, we may build a commercial infrastructure with the capability to directly market it to a variety of markets and geographies. Although we currently plan to retain all commercial rights to APR-246 and our product candidates, we may enter into strategic collaborations for the development, marketing and commercialization of APR-246 and our other product candidates. Our likely collaborators for any collaboration arrangements include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies and biotechnology companies. If we do enter into any such arrangements with any third parties, we will likely have limited control over the amount and timing of resources that our collaborators dedicate to the development, marketing and/or commercialization of our product candidates. Our ability to generate revenues from these arrangements will depend on our collaborators' abilities to successfully perform the functions assigned to them in these arrangements. In addition, any future collaborators may have the right to abandon research or development projects and terminate applicable agreements, including funding obligations, prior to or upon the expiration of the agreed upon terms.

        Collaborations involving our product candidates would pose the following risks to us:

    collaborators have significant discretion in determining the efforts and resources that they will apply to these collaborations;

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    collaborators may not perform their obligations as expected;

    collaborators may not pursue development, marketing and/or commercialization of our product candidates or may elect not to continue or renew development, marketing or commercialization programs based on clinical trial results, changes in the collaborator's strategic focus or available funding or external factors such as an acquisition that diverts resources or creates competing priorities;

    collaborators may delay clinical trials, provide insufficient funding for a clinical trial program, stop a clinical trial or abandon a product candidate, repeat or conduct new clinical trials or require a new formulation of a product candidate for clinical testing;

    collaborators could independently develop, or develop with third parties, drugs that compete directly or indirectly with our product candidates or product candidates;

    a collaborator with marketing and distribution rights to one or more drugs may not commit sufficient resources to the marketing and distribution of such drug or drugs;

    disagreements with collaborators, including disagreements over proprietary rights, contract interpretation or the preferred course of development, might cause delays or termination of the research, development or commercialization of product candidates, might lead to additional responsibilities for us with respect to product candidates, or might result in litigation or arbitration, any of which would be time-consuming and expensive;

    collaborators may not properly obtain, maintain, defend and enforce our intellectual property rights or may use our proprietary information in such a way as to invite litigation that could jeopardize or invalidate our proprietary information or expose us to potential litigation;

    collaborators may infringe, misappropriate or otherwise violate the intellectual property rights of third parties, which may expose us to litigation and potential liability;

    we may lose certain valuable rights under circumstances identified in any collaboration arrangement that we enter into, such as if we undergo a change of control;

    collaborations may be terminated and, if terminated, may result in a need for additional capital to pursue further development, marketing and/or commercialization of the applicable product candidates;

    collaborators may learn about our discoveries, data, proprietary information, trade secrets, or compounds and use this knowledge to compete with us in the future; and

    the number and type of our collaborations could adversely affect our attractiveness to future collaborators or acquirers.

        Collaboration agreements may not lead to development or commercialization of product candidates in the most efficient manner, or at all.

Risks related to our intellectual property

If we are unable to obtain and maintain intellectual property protection for APR-246 or any other product candidates we develop or for our technology, our competitors could develop and commercialize products or technology similar or identical to ours, and our ability to successfully commercialize APR-246 or any product candidates we may develop, and our technology may be adversely affected.

        Our commercial success will depend in large part on obtaining and maintaining patent, trademark and trade secret protection of our proprietary technologies and our product candidates, which include APR-246 and others, their respective components, formulations, methods used to manufacture them and methods of treatment, as well as successfully defending these patents against third-party challenges.

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We seek to protect our proprietary position by filing patent applications in the United States and abroad relating to our product candidates as well as other technologies that are important to our business. Our ability to stop unauthorized third parties from making, using, selling, offering to sell or importing our product candidates is dependent upon the extent to which we have rights under valid and enforceable patents or trade secrets that cover these activities.

        The chemical structure of APR-246 is in the public domain. Accordingly, we do not own or license any composition of matter patents claiming the compound of APR-246 and will not in the future own or license any composition of matter patents claiming the chemical structure of APR-246 as described in the public domain. Our patent portfolio for APR-246 currently consists of method-of-use and formulation patent claims, and dosing, manufacturing processes, and crystalline solid form provisional patent application claims. Our existing patents and any future patents we obtain may not be sufficiently broad to prevent others from using our technology or from developing competing products and technologies. Any failure to obtain or maintain patent protection with respect to APR-246 and our other product candidates could have a material adverse effect on our business, financial condition, results of operations and growth prospects. If it is later determined that our activities or product candidates infringe, misappropriate or otherwise violate the intellectual property of third parties we may be liable for damages, enhanced damages or subjected to an injunction, any of which could have a material adverse effect on our business.

        The patenting process is expensive and time-consuming, and we may not be able to file and prosecute all necessary or desirable patent applications at a reasonable cost or in a timely manner. In addition, we may not pursue or obtain patent protection in all relevant markets. During the course of business we have decided not to pursue certain products or processes and have not pursued certain corresponding intellectual property. However, we may decide to pursue such products or processes again in the future. It is also possible that we will fail to identify patentable aspects of our research and development output before it is too late to obtain patent protection.

        The patent position of pharmaceutical and biotechnology companies generally is highly uncertain and involves complex legal and factual questions for which many legal principles remain unresolved. In recent years patent rights have been the subject of significant litigation. As a result, the issuance, scope, validity, enforceability and commercial value of our patent rights are highly uncertain. Our pending and future patent applications may not result in patents being issued in the United States or in other jurisdictions which protect our technology or products or which effectively prevent others from commercializing competitive technologies and products.

        Our ability to obtain and maintain valid and enforceable patents depends on whether the differences between our inventions and the prior art, including our own previously filed patent applications and scientific publications, allow our inventions to be patentable over the prior art. We are aware of certain scientific publications by our inventors and other third parties that disclose subject matter, including the composition of APR-246, relating to certain of our patents, that may be used by third parties to challenge the validity and enforceability of our patents and patent applications. If such third parties are successful, we could lose valuable patent rights. In the United States, an inventor's own publication cannot be used as prior art to the inventor's patent application on the same subject matter when published less than one year before the effective filing date of the patent application. Such a publication may be considered prior art in certain jurisdictions that do not provide such a grace period. Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all. Therefore, we cannot be certain that we were the first to make the inventions claimed in our patents or pending patent applications, or that we were the first to file for patent protection of such inventions. In addition, the U.S. Patent and Trademark Office, or USPTO, might require that the term of a patent issuing from a pending patent application be disclaimed and limited to the term of another patent that is commonly owned or names a common

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inventor. Although we enter into non-disclosure and confidentiality agreements with parties who have access to confidential or patentable aspects of our research and development output, such as our employees, corporate collaborators, outside scientific collaborators, CROs, contract manufacturers, consultants, advisors, and other third parties, certain of these parties have and others may in the future breach the agreements and disclose such output before a patent application is filed, thereby jeopardizing our ability to seek patent protection.

        Moreover, the coverage claimed in a patent application can be significantly reduced before the patent is issued, and its scope can be reinterpreted after issuance. Even if our patent applications issue as patents, they may not issue in a form that will provide us with any meaningful protection, prevent competitors from competing with us or otherwise provide us with any competitive advantage. Our competitors may be able to circumvent our patents by developing similar or alternative technologies or products in a non-infringing manner.

        The issuance of a patent is not conclusive as to its inventorship, scope, validity or enforceability, and our patents may be challenged in the courts or patent offices in the United States and abroad. Such challenges may result in the patent claims of our patents being narrowed, invalidated or held unenforceable, which could limit our ability to stop or prevent us from stopping others from using or commercializing similar or identical technology and products, or limit the duration of the patent protection of our technology and products. In addition, some of our owned patents and patent applications may in the future be co-owned with third parties. If we do not have exclusive control of the grant of licenses under any such third-party co-owners' interest in such patents or patent applications or we are otherwise unable to secure such exclusive rights, such co-owners may be able to license their rights to other third parties, including our competitors, and our competitors could market competing products and technology. In addition, we may need the cooperation of any such co-owners of our co-owned patents in order to enforce such patents against third parties, and such cooperation may not be provided to us.

        Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours or otherwise provide us with a competitive advantage. Upon the expiration of our current patents, we may lose the right to exclude others from practicing these inventions, including APR-246 based on patent exclusivity. The expiration of these patents could also have a similar material adverse effect on our business, results of operations, financial condition and prospects.

Our proprietary position for APR-246 depends upon patents that consist of method-of-use and formulation patent claims, which may not prevent a competitor or other third party from using the same product candidate for another use or in another formulation.

        Composition-of-matter patent claims on the active pharmaceutical ingredient, or API, in pharmaceutical drug products are generally considered to be the favored form of intellectual property protection for drug products because such patents may provide protection without regard to any particular method of use or manufacture or formulation of the API used. The chemical structure of APR-246 is in the public domain. Accordingly, we do not own or license any composition of matter patents claiming the compound of APR-246 and will not in the future own or license any composition of matter patents claiming the chemical structure of APR-246 as described in the public domain.

        Method-of-use patent claims protect the use of a product for the specified method and dosing or formulation patent claims cover dosing regimens or formulations of the API. These types of patent claims do not prevent a competitor or other third party from marketing an identical API for an indication that is outside the scope of the method claims or from developing a different dosing regimen

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or formulation that is outside the scope of the dosing or formulation claims. Moreover, with respect to method-of-use patents, even if competitors or other third parties do not actively promote their product for our targeted indications or uses for which we may obtain patents, physicians may recommend that patients use these products off-label, or patients may do so themselves. Although off-label use may infringe or contribute to the infringement of method-of-use patents, the practice is common and such infringement is difficult to prevent or prosecute. In addition, there are numerous publications and other prior art that may be relevant to our patents and may be used to challenge the validity of such patents in litigation or other intellectual property-related proceedings. If such challenges are successful, our patents may be narrowed or found to be invalid and we may lose valuable intellectual property rights. Any of the foregoing could have a material adverse effect on our business, financial conditions and results of operations and prospects.

Issued patents covering our product candidates and other technologies could be narrowed or found invalid or unenforceable if challenged in court or before administrative bodies in the United States or abroad.

        If we seek to enforce a patent covering our product candidates or other technologies against a third party, that third party could assert that such patent is invalid or unenforceable. In patent litigation in the United States, challenges to validity or enforceability are commonplace. Grounds for a validity challenge could be an alleged failure to meet any of several statutory requirements, including lack of patentable subject matter, lack of novelty, obviousness, inadequate written description, indefiniteness, or lack of enablement. Grounds for an unenforceability assertion could be an allegation that relevant information was withheld from or a misleading statement was made to the USPTO during prosecution.

        In addition, third parties may raise claims challenging the validity or enforceability of our patents before administrative bodies in the United States or abroad, even outside the context of litigation. Such mechanisms include preissuance submission of prior art to the USPTO and re-examination, post-grant review, inter partes review, interference proceedings, derivation proceedings, and equivalent proceedings in foreign jurisdictions (e.g., opposition proceedings). Moreover, we may have to participate in interference proceedings declared by the USPTO to determine priority of invention or in post-grant challenge proceedings, such as oppositions in a foreign patent office, that challenge our priority of invention or other features of patentability with respect to our patents and patent applications. An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate or render unenforceable, our patent rights, allow third parties to commercialize our product candidates or other technologies and compete directly with us, without payment to us.

        In the United States, an inventor's own publication may not be effective prior art to the inventor's patent application on the same subject matter when published less than one year before the effective filing date of the patent application. Such a publication might be considered prior art in certain jurisdictions that do not provide such a grace period. For those non-US jurisdictions, reliance on non-patent exclusivity may provide sufficient competitive protection to exclude others from commercializing generic versions of our products.

        Such proceedings also may result in substantial cost and require significant time from our scientists and management, even if the eventual outcome is favorable to us. If we are unsuccessful in any such proceeding or other priority or inventorship dispute, we may be required to obtain and maintain licenses from third parties, including parties involved in any such interference proceedings or other priority or inventorship disputes. Such licenses may not be available on commercially reasonable terms or at all, or may be non-exclusive. If we are unable to obtain and maintain such licenses, we may need to cease the development, manufacture, and commercialization of one or more of the product candidates we may develop. The loss of exclusivity or the narrowing of our patent claims could limit our ability to stop others from using or commercializing similar or identical technology and products. Any of the foregoing could have a material adverse effect on our business, results of operations, financial condition and prospects.

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We may be subject to other claims challenging the inventorship of our patents and other intellectual property.

        We may also be subject to claims that former employees, collaborators or other third parties have an interest in our patents, trade secrets, or other intellectual property as an inventor or co-inventor. For example, we may have inventorship disputes arise from conflicting obligations of employees, consultants or others who are involved in developing our product candidates or other technologies. Litigation may be necessary to defend against these and other claims challenging inventorship of our patents, trade secrets or other intellectual property. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights, such as exclusive ownership of, or right to use, intellectual property that is important to our product candidates and other technologies. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees. Any of the foregoing could have a material adverse effect on our business, financial condition, results of operations and growth prospects.

If we do not obtain patent term extension or data exclusivity for any product candidates we may develop, our business may be materially harmed.

        Depending upon the timing, duration and specifics of any FDA marketing approval of any product candidates we may develop, one or more of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Act. The Hatch-Waxman Act permits a patent term extension of up to five years as compensation for patent term lost during the FDA regulatory review process. A patent term extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval, only one patent may be extended and only those claims covering the approved drug, a method for using it, or a method for manufacturing it may be extended. Similar extensions as compensation for patent term lost during regulatory review processes are also available in certain foreign countries and territories, such as in Europe under a Supplementary Patent Certificate. However, we may not be granted an extension in the United States and/or foreign countries and territories because of, for example, failing to exercise due diligence during the testing phase or regulatory review process, failing to apply within applicable deadlines, failing to apply prior to expiration of relevant patents, or otherwise failing to satisfy applicable requirements. Moreover, the applicable time period or the scope of patent protection afforded could be less than we request. If we are unable to obtain patent term extension or the term of any such extension is shorter than what we request, our competitors may obtain approval of competing products following our patent expiration, and our business, financial condition, results of operations and growth prospects could be materially harmed.

We may not be successful in obtaining, through acquisitions, in-licenses or otherwise, rights that may be necessary to our product candidates or other technologies.

        The growth of our business may depend in part on our future ability to acquire or in-license any relevant third-party proprietary rights that we may identify as necessary or important to our business operations. For example, our programs may involve additional product candidates that may require the use of additional proprietary rights held by third parties. Our product candidates may also require specific formulations to work effectively and efficiently. These formulations may be covered by intellectual property rights held by others. We may develop products containing our compounds and pre-existing pharmaceutical compounds. These pharmaceutical compounds may be covered by intellectual property rights held by others. We may be required by the FDA or comparable foreign regulatory authorities to provide a companion diagnostic test or tests with our product candidates. These diagnostic test or tests may be covered by intellectual property rights held by others. We may be unable to acquire or in-license such third-party intellectual property rights. We may fail to obtain any of

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these licenses at a reasonable cost or on reasonable terms, if at all, which would harm our business. We may need to cease use of the compositions or methods covered by such third-party intellectual property rights, and may need to seek to develop alternative approaches that do not infringe, misappropriate or otherwise violate intellectual property rights which may entail additional costs and development delays, even if we were able to develop such alternatives, which may not be feasible. Even if we are able to obtain a license to such intellectual property rights, any such license may be non-exclusive, which may allow our competitors access to the same technologies licensed to us.

        Additionally, we sometimes collaborate with academic institutions and clinical research organizations to accelerate our research or development, including our research or development of APR-246, under written agreements with these institutions and organizations. In certain cases, these institutions and organizations may own or jointly own with us inventions that are created under such collaborations and provide us with an option to negotiate a license to any of the institution's rights in such inventions. Regardless of such option, we may be unable to negotiate a license within the specified timeframe or under terms that are acceptable to us. If we are unable to do so, the institution or organization may offer the intellectual property rights to others, potentially blocking our ability to pursue our program and allowing third parties to compete with us.

        The licensing and acquisition of third-party intellectual property rights is a competitive practice, and companies that may be more established, or have greater resources than we do, may also be pursuing strategies to license or acquire third-party intellectual property rights that we may consider necessary or attractive in order to commercialize our product candidates. More established companies may have a competitive advantage over us due to their larger size and cash resources or greater clinical development and commercialization capabilities. In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. We also may be unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return on our investment or at all. There can be no assurance that we will be able to successfully complete such negotiations and ultimately acquire the rights to the intellectual property surrounding the additional product candidates that we may seek to acquire. If we are unable to successfully obtain rights to third-party intellectual property that may be necessary, we may have to abandon development of such program and our business, results of operations, financial condition and prospects could suffer.

Changes in U.S. patent law could diminish the value of patents in general, thereby impairing our ability to protect our product candidates and technology.

        Recent or future patent reform legislation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents. Assuming that other requirements for patentability are met, prior to March 2013, in the United States, the first to invent the claimed invention was entitled to the patent, while outside the United States, the first to file a patent application was entitled to the patent regardless of whether another inventor had made the invention earlier. In March 2013, under the Leahy-Smith America Invents Act, or America Invents Act, the United States moved from a "first-to-invent" to a "first-to-file" system. Under a "first-to-file" system, assuming the other requirements for patentability are met, the first inventor to file a patent application generally will be entitled to a patent on the invention regardless of whether another inventor had made the invention earlier. A third party that files a patent application in the USPTO after March 2013, but before us, could therefore be awarded a patent covering an invention of ours even if we had made the invention before it was made by such third party. Since patent applications in the United States and most other countries are confidential for a period of time after filing or until issuance, we cannot be certain that we were the first to either (i) file any patent application related to our product candidates or other technologies or (ii) invent any of the inventions claimed in our patents or patent applications.

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        The America Invents Act includes a number of other significant changes to U.S. patent law, including provisions that affect the way patent applications are prosecuted, redefine prior art and establish a new post-grant review system. These include allowing third party submission of prior art to the USPTO during patent prosecution and additional procedures to attack the validity of a patent by USPTO-administered post-grant proceedings, including post-grant review, inter partes review, and derivation proceedings. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in United States federal courts necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action. Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party in a district court action. An adverse determination in any such proceeding could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology or products and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize products without infringing third-party patent rights, all of which could have a material adverse effect on our business and financial condition. Accordingly, the America Invents Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents.

        In addition, the patent positions of companies in the development and commercialization of biologics and pharmaceuticals are particularly uncertain. Recent U.S. Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. This combination of events has created uncertainty with respect to the validity and enforceability of patents, once obtained. Depending on future actions by the U.S. Congress, the federal courts, and the USPTO, the laws and regulations governing patents could change in unpredictable ways that could have a material adverse effect on our existing patent portfolio and our ability to protect and enforce our intellectual property in the future.

We may become involved in lawsuits to protect or enforce our patents and other intellectual property rights, which could be expensive, time consuming and unsuccessful.

        Competitors may infringe our patents, or we may be required to defend against claims of infringement. In addition, our patents also may become involved in inventorship, priority, validity or unenforceability disputes. To counter or defend against such claims can be expensive and time consuming. We may not prevail in any lawsuits that we initiate, and the damages or other remedies awarded, if any, may not be commercially meaningful. For example, in an infringement proceeding, a court may decide that a patent owned by us is invalid or unenforceable. There is also the risk that, even if the validity of these patents is upheld, the court will refuse to stop the third party on the ground that such third party's activities do not infringe our owned patents, including finding that the other party's use of our patented technology falls under the safe harbor to patent infringement under 35 U.S.C. § 271(e)(1). Even if resolved in our favor, these lawsuits are expensive and would consume time and other resources, including distracting our personnel from their normal responsibilities. In addition, there could be public announcements of the results of hearings, motions, or other interim proceedings or developments, and if securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our common stock. Such litigation or proceedings could substantially increase our operating losses and reduce the resources available for development activities or any future sales, marketing, or distribution activities. We may not have sufficient financial or other resources to conduct such litigation or proceedings adequately. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we can because of their greater financial resources and more mature and developed intellectual property portfolios. Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could have a material adverse effect on our ability to compete in the marketplace.

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Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation.

        We may not be able to detect infringement against our patents which may be more difficult for formulation patents. Even if we detect infringement by a third party of our patents, we may choose not to pursue litigation against or settlement with the third party. If we later sue such third party for patent infringement, the third party may have certain legal defenses available to it, which otherwise would not be available except for the delay between when the infringement was first detected and when the suit was brought. Such legal defenses may make it impossible for us to enforce our patents against such third party.

        If another party questions the patentability of any of our claims in our U.S. patents, the third party can request that the USPTO review the patent claims such as in an inter partes review, ex parte re-exam or post-grant review proceedings. These proceedings are expensive and may result in a loss of scope of some claims or a loss of the entire patent. In addition to potential USPTO review proceedings, we may become a party to patent opposition proceedings in the European Patent Office, or EPO, or similar proceedings in other foreign patent offices, where either our foreign patents are challenged. The costs of these opposition or similar proceedings could be substantial, and may result in a loss of scope of some claims or a loss of the entire patent. An unfavorable result at the USPTO, EPO or other patent office may result in the loss of our right to exclude others from practicing one or more of our inventions in the relevant country or jurisdiction, which could have a material adverse effect on our business.

If we are sued for infringing, misappropriating or otherwise violating patents or other intellectual property rights of third parties, it will be costly and time consuming, and an unfavorable outcome in that litigation would have a material adverse effect on our business.

        Our commercial success depends upon our ability to develop, manufacture, market and sell our product candidates and use our proprietary technologies without infringing, misappropriating or otherwise violating the intellectual property rights of third parties. There is a substantial amount of litigation involving patents and other intellectual property rights in the biotechnology and pharmaceutical industries. We may be exposed to, or threatened with, future litigation by third parties having patent or other intellectual property rights alleging that our product candidates and/or proprietary technologies infringe, misappropriate or otherwise violate their intellectual property rights. We cannot guarantee that our product candidates and other technologies that we have developed, are developing or may develop in the future will not infringe existing or future patents owned by third parties. U.S. and foreign issued patents and pending patent applications, which are owned by third parties, exist in the fields relating to our product candidates. As the biotechnology and pharmaceutical industries expand and more patents are issued, the risk increases that others may assert our product candidates infringe the patent rights of others. Moreover, it is not always clear to industry participants, including us, which patents cover various types of drugs, products or their methods of use or manufacture. Thus, because of the large number of patents issued and patent applications filed in our fields, there may be a risk that third parties may allege they have patent rights encompassing our product candidates, technologies or methods. It is also possible that patents owned by third parties of which we are aware, but which we do not believe are relevant to our product candidates or other technologies, could be found to be infringed by our product candidates or other technologies. In addition, because some patent applications in the United States may be maintained in secrecy until the patents are issued, patent applications in the United States and many foreign jurisdictions are typically not published until 18 months after filing, and publications in the scientific literature often lag behind actual discoveries, we cannot be certain that others have not filed patent applications covering our product candidates or technology. If any such patent applications issue as patents, and if such patents

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have priority over our patent applications or patents, we may be required to obtain rights to such patents owned by third parties which may not be available on commercially reasonable terms or at all, or may only be available on a non-exclusive basis.

        If a third party claims that we infringe its intellectual property rights, we may face a number of issues even if we believe such claims are without merit, including, but not limited to:

    infringement and other intellectual property claims which, regardless of merit, may be expensive and time-consuming to litigate, may divert our management's attention from our core business and may impact our reputation;

    substantial damages for infringement, which we may have to pay if a court decides that the product candidate or technology at issue infringes on or violates the third party's rights, and, if the court finds that the infringement was willful, we could be ordered to pay treble damages and the patent owner's attorneys' fees;

    a court prohibiting us from developing, manufacturing, marketing or selling our product candidates, including APR-246, or from using our proprietary technologies, unless the third party licenses its patent rights to us, which it is not required to do;

    if a license is available from a third party, we may have to pay substantial royalties, upfront fees and other amounts, and/or grant cross-licenses to intellectual property rights for our product candidates or such license is only available on a non-exclusive basis; and

    redesigning our product candidates or processes so they do not infringe, which may not be possible or may require substantial monetary expenditures and time.

Some of our competitors may be able to sustain the costs of complex patent litigation more effectively than we can because they have substantially greater resources. In addition, any uncertainties resulting from the initiation and continuation of any litigation could have a material adverse effect on our ability to raise the funds necessary to continue our operations or could otherwise have a material adverse effect on our business, results of operations, financial condition and prospects. The occurrence of any of the foregoing could have a material adverse effect on our business, financial condition, results of operations or growth prospects.

        We may choose to challenge the patentability of claims in a third party's U.S. patent by requesting that the USPTO review the patent claims in an ex-parte re-exam, inter partes review or post-grant review proceedings. These proceedings are expensive and may consume our time or other resources. We may choose to challenge a third party's patent in patent opposition proceedings in the EPO, or other foreign patent office. The costs of these opposition proceedings could be substantial, and may consume our time or other resources. If we fail to obtain a favorable result at the USPTO, EPO or other patent office then we may be exposed to litigation by a third party alleging that the patent may be infringed by our product candidates or proprietary technologies.

We may not be able to protect our intellectual property rights with patents throughout the world.

        Filing, prosecuting and defending patents on all of our product candidates throughout the world would be prohibitively expensive, and the laws of some foreign countries may not protect our rights to the same extent as the laws of the United States. Competitors may use our technology in jurisdictions where we have not obtained patent protection to develop their own products and, further, may export otherwise infringing products to territories where we have patent protection but where enforcement is not as strong as in the United States. These products may compete with our product candidates in jurisdictions where we do not have any issued patents and our patent claims or other intellectual property rights may not be effective or sufficient to prevent them from so competing. Many companies have encountered significant problems in protecting and defending intellectual property rights in

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foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents and other intellectual property protection, particularly those relating to biopharmaceuticals, which could make it difficult for us to stop the infringement of our patents or marketing of competing products against third parties in violation of our proprietary rights generally. The initiation of proceedings to enforce our intellectual property rights or proceedings by third parties to challenge the scope or validity of our patent rights in foreign jurisdictions could result in substantial cost and divert our efforts and attention from other aspects of our business and could put our patents at risk of being invalidated or interpreted narrowly.

        Many countries have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties. In addition, many countries limit the enforceability of patents against government agencies or government contractors. In these countries, the patent owner may have limited remedies, which could materially diminish the value of such patent. If we are forced to grant a license to third parties with respect to any patents relevant to our business, our competitive position may be impaired, and our business, financial condition, results of operations, and growth prospects may be adversely affected.

Obtaining and maintaining our patent protection depends upon compliance with various procedural, document submission, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

        The USPTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other provisions during the patent prosecution process and following the issuance of a patent. In some cases, an inadvertent failure to comply with such requirements can be cured by payment of a late fee or by other means in accordance with the applicable rules. There are situations, however, in which non-compliance could result in abandonment or lapse of a patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. In such an event, competitors might be able to enter the market earlier than would otherwise have been the case if our patent were in force, which would have a material adverse effect on our business.

We may be subject to claims that our employees, consultants or advisors have wrongfully used or disclosed alleged trade secrets of their current or former employers or claims asserting ownership of what we regard as our own intellectual property.

        As is common in the biotechnology and pharmaceutical industries, we employ individuals who were previously employed at other biotechnology or pharmaceutical companies, including our competitors or potential competitors. Although no claims against us are currently pending, we may be subject to claims that these employees, consultants or advisors or we have inadvertently or otherwise used or disclosed trade secrets or other proprietary information of their current or former employers. Litigation may be necessary to defend against these claims. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Even if we are successful in defending against such claims, litigation or other legal proceedings relating to intellectual property claims may cause us to incur significant expenses, and could distract our technical and management personnel from their normal responsibilities. In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments, and, if securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our common stock. This type of litigation or proceeding could substantially increase our operating losses and reduce our resources available for development activities. We may not have sufficient financial or other resources to adequately conduct such litigation or proceedings. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we can because of their substantially greater financial resources.

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Uncertainties resulting from the initiation and continuation of patent litigation or other intellectual property related proceedings could adversely affect our ability to compete in the marketplace.

        In addition, while it is our policy to require our employees and contractors who may be involved in the conception or development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who, in fact, conceives or develops intellectual property that we regard as our own. The assignment of intellectual property rights may not be self-executing, or the assignment agreements may be breached, and we may be forced to bring claims against third parties, or defend claims that they may bring against us, to determine the ownership of what we regard as our intellectual property. Such claims could have a material adverse effect on our business, financial condition, results of operations, and growth prospects.

Confidentiality agreements with employees and third parties may not prevent unauthorized disclosure of trade secrets and other proprietary information.

        In addition to the protection afforded by patents, we rely on trade secret protection and confidentiality agreements to protect proprietary know-how that is not patentable or that we elect not to patent, processes for which patents are difficult to enforce and any other elements of our platform technology and discovery and development processes that involve proprietary know-how, information or technology that is not covered by patents. However, trade secrets can be difficult to protect and we have limited control over the protection of trade secrets used by our collaborators and suppliers. Although we seek to protect our proprietary technology and processes, in part, by entering into confidentiality agreements with parties who have access them, such as our employees, consultants, and outside scientific advisors, contractors and collaborators, we cannot guarantee that we have entered into such agreements with each party that may have or have had access to our trade secrets or proprietary technology and processes. Despite our efforts, any of these parties might breach the agreements and intentionally or inadvertently disclose our trade secret information and we may not be able to obtain adequate remedies for such breaches. In addition, competitors may otherwise gain access to our trade secrets or independently develop substantially equivalent information and techniques. Moreover, our competitors or other third parties may independently develop equivalent knowledge, methods and know-how.

        Enforcing a claim that a third party illegally obtained and is using any of our trade secrets is expensive and time consuming, and the outcome is unpredictable. In addition, courts inside and outside the United States sometimes are less willing or unwilling to protect trade secrets. If we choose to go to court to stop a third party from using any of our trade secrets, we may incur substantial costs. These lawsuits may consume our time and other resources even if we are successful. If any of our trade secrets were determined to be lawfully obtained or independently developed by a competitor or other third party, we may not be able to prevent them from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor or other third party, our competitive position, business, results of operations and prospects would be materially and adversely harmed.

Intellectual property rights do not necessarily address all potential threats.

        The degree of future protection for our proprietary rights is uncertain because legal means afford only limited protection and may not adequately protect our rights or permit us to gain or keep our competitive advantage. For example:

    others may be able to make or use compounds that are similar to the pharmaceutical compounds used in our product candidates but that are not covered by the claims of our patents;

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    the APIs in our current product candidates will eventually become commercially available in generic drug products, and no patent protection may be available with regard to formulation or method of use;

    we, or our future licensors or collaborators, might not have been the first to file patent applications for these inventions;

    we, or our future licensors or collaborators, might not have been the first to make the inventions covered by our issued patents or pending patent applications;

    others may independently develop similar or alternative technologies or duplicate any of our technologies;

    it is possible that our current or future pending or licensed patent applications will not result in issued patents;

    it is possible that public disclosures or publications, including disclosures or publications made by us, could be used in an attempt to invalidate our patents;

    issued patents that we hold rights to may be held invalid or unenforceable, including as a result of legal challenges by our competitors or other third parties;

    our competitors or other third parties might conduct research and development activities in countries where we do not have patent rights and then use the information learned from such activities to develop competitive products for sale in our major commercial markets;

    it is possible that others may circumvent our patents;

    it is possible that there are unpublished applications or patent applications maintained in secrecy that may later issue with claims covering our products or technology similar to ours;

    the laws of foreign countries may not protect our proprietary rights to the same extent as the laws of the United States;

    the claims of our issued patents or patent applications, if and when issued, may not cover our product candidates;

    our issued patents may not provide us with any competitive advantages, may be narrowed in scope, or be held invalid or unenforceable as a result of legal challenges by third parties;

    the inventors of our patents or patent applications may become involved with competitors, develop products or processes which design around our patents, or become hostile to us or the patents or patent applications on which they are named as inventors;

    we have engaged in scientific collaborations in the past and will continue to do so in the future. Such collaborators may develop adjacent or competing products to ours that are outside the scope of our patents;

    we may not develop additional proprietary technologies for which we can obtain patent protection;

    we may choose not to pursue patent protection in order to maintain certain trade secrets or know-how, and a third party may subsequently obtain a patent covering such intellectual property;

    it is possible that product candidates or diagnostic tests we develop may be covered by third parties' patents or other exclusive rights; or

    the patents of others may have an adverse effect on our business.

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Should any of these events occur, they could have a material adverse effect on our business, financial condition, results of operations and growth prospects.

Risks related to regulatory and marketing approval and other legal compliance matters

We have never obtained marketing approval for a product candidate and we may be unable to obtain, or may be delayed in obtaining, marketing approval for any of our product candidates.

        We have never obtained marketing approval for a product candidate. The time required to obtain approval by the FDA and comparable foreign regulatory authorities is unpredictable but typically takes many years following the commencement of preclinical studies and clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities. It is possible that the FDA and comparable foreign regulatory authorities may refuse to accept for filing and substantive review any new drug applications, or NDAs, marketing authorization applications, or MAA, that we submit for our product candidates or may conclude after review of our data that our application is insufficient to obtain marketing approval of our product candidates. If the FDA, or comparable foreign regulatory authorities do not accept or approve our NDAs or MAAs for our product candidates, it may require that we conduct additional clinical, nonclinical or manufacturing validation studies and submit that data before it will reconsider our applications. Depending on the extent of these or any other regulatory authority-required studies, approval of any NDA, MAA or other application that we submit may be delayed by several years, or may require us to expend more resources than we have available. It is also possible that additional studies, if performed and completed, may not be considered sufficient by the FDA or comparable foreign regulatory authorities to approve our NDAs or our MAAs.

        Any delay in obtaining, or an inability to obtain, marketing approvals would prevent us from commercializing our product candidates, generating revenues and achieving and sustaining profitability. If any of these outcomes occur, we may be forced to abandon our development efforts for our product candidates, which could significantly harm our business.

Even if we complete the necessary preclinical studies and clinical trials, the marketing approval process is expensive, time-consuming and uncertain and may prevent us, or any future collaborators, from obtaining approvals for the commercialization of some or all of our product candidates. As a result, we cannot predict when or if, and in which territories, we, or any future collaborators, will obtain marketing approval to commercialize a product candidate.

        The research, testing, manufacturing, labeling, approval, selling, marketing, promotion and distribution of drugs are subject to extensive regulation by the FDA and comparable foreign regulatory authorities, whose laws and regulations may differ from country to country. We, and any future collaborators, are not permitted to market our product candidates in the United States or in other countries until we or they receive approval of an NDA from the FDA or marketing approval from comparable foreign regulatory authorities. Our product candidates are in early stages of development and are subject to the risks of failure inherent in drug development. We have not submitted an application for or received marketing approval for any of our product candidates in the United States or in any other jurisdiction. We have limited experience in conducting and managing the clinical trials necessary to obtain marketing approvals, including FDA approval of an NDA.

        The process of obtaining marketing approvals, both in the United States and abroad, is a lengthy, expensive and uncertain process. It may take many years, if approval is obtained at all, and can vary substantially based upon a variety of factors, including the type, complexity and novelty of the product candidates involved. Securing marketing approval requires the submission of extensive preclinical and clinical data and supporting information to regulatory authorities for each therapeutic indication to establish the product candidate's safety and efficacy. Securing marketing approval also requires the submission of information about the product manufacturing process to, and inspection of

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manufacturing facilities by, the regulatory authorities. The FDA or other comparable foreign regulatory authorities have substantial discretion and may determine that our product candidates are not safe and effective, only moderately effective or have undesirable or unintended side effects, toxicities or other characteristics that preclude our obtaining marketing approval or prevent or limit commercial use. Any marketing approval we ultimately obtain may be limited or subject to restrictions or post-approval commitments that render the approved product not commercially viable.

        Our product candidates could fail to receive marketing approval, or marketing approval for our product candidates could be limited or delayed, for many reasons, including the following:

    the FDA or comparable foreign regulatory authorities may disagree with the design or implementation of our clinical trials;

    we may be unable to demonstrate to the satisfaction of the FDA or comparable foreign regulatory authorities that a product candidate is safe and effective for its proposed indication;

    the results of clinical trials may not meet the level of statistical significance required by the FDA or comparable foreign regulatory authorities for approval;

    we may be unable to demonstrate that a product candidate's clinical and other benefits outweigh its safety risks;

    the FDA or comparable foreign regulatory authorities may disagree with our interpretation of data from preclinical studies or clinical trials;

    the data collected from clinical trials of our product candidates may not be sufficient to support the submission of an NDA or other submission and applications or to obtain marketing approval in the United States or elsewhere;

    the FDA or comparable foreign regulatory authorities may fail to approve the manufacturing processes or facilities of third-party manufacturers with which we contract for clinical and commercial supplies;

    the FDA or comparable foreign regulatory authorities may fail to approve any companion diagnostics that may be required in connection with approval of our therapeutic product candidates

    the FDA or the applicable foreign regulatory agency may fail to approve the formulation, labeling and/or the specifications for our product candidate

    changes in marketing approval policies during the development period, changes in or the enactment or promulgation of additional statutes, regulations or guidance or changes in regulatory review for each submitted drug application; and

    the approval policies or regulations of the FDA or comparable foreign regulatory authorities may significantly change in a manner rendering our clinical data insufficient for approval.

        This lengthy approval process as well as the unpredictability of clinical trial results may result in our failing to obtain marketing approval to market APR-246, which would significantly harm our business, results of operations and prospects. Regulatory authorities have substantial discretion in the approval process and may refuse to accept any application or may decide that our data are insufficient for approval and require additional preclinical studies, clinical trials or other studies and testing. In addition, varying interpretations of the data obtained from preclinical studies and clinical trials could delay, limit or prevent marketing approval of a product candidate. Any marketing approval we, or any collaborators we may have in the future, ultimately obtain may be limited or subject to restrictions or post-approval commitments that render the approved drug not commercially viable.

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        Any delay in obtaining or failure to obtain required approvals could materially adversely affect our ability or that of any collaborators we may have to generate revenue from the particular product candidate, which likely would result in significant harm to our financial position and adversely impact our stock price.

Failure to obtain marketing approval in foreign jurisdictions would prevent our product candidates from being marketed abroad. Any approval we are granted for our product candidates in the United States would not assure approval of our product candidates in foreign jurisdictions.

        In order to market and sell our product candidates in the EU and many other jurisdictions, we, and any collaborators we may have in the future, must obtain separate marketing approvals and comply with numerous and varying regulatory requirements. The approval procedure varies among countries and can involve additional testing. The time required to obtain approval may differ substantially from that required to obtain FDA approval. The marketing approval process outside of the United States generally includes all of the risks associated with obtaining FDA approval. In addition, in many countries outside of the United States, it is required that the drug be approved for reimbursement before the drug can be approved for sale in that country. We, and any collaborators we may have in the future, may not obtain approvals from regulatory authorities outside of the United States on a timely basis, if at all. Approval by the FDA does not ensure approval by regulatory authorities in other countries or jurisdictions, and approval by one regulatory authority outside of the United States does not ensure approval by regulatory authorities in other countries or jurisdictions or by the FDA.

        On June 23, 2016, the electorate in the United Kingdom, or the U.K., voted in favor of leaving the EU, commonly referred to as Brexit. The U.K. government communicated the notice of withdrawal to the EU on March 29, 2017. As part of the withdrawal process, the U.K. government and the EU negotiated a withdrawal agreement that was approved by the U.K. Prime Minister and the leaders of EU member states. However, under U.K. law, such agreement also requires the approval of the U.K. parliament, and the U.K. parliament has to date refused to approve the agreement. While negotiations are continuing, there remains considerable uncertainty around the withdrawal. As a result, the EU and the U.K. have agreed to delay the date on which the U.K. will leave the EU to October 31, 2019, although if the U.K. parliament approves the withdrawal agreement prior to that date, it is possible that the U.K. may leave the EU on an earlier date; however, failure to obtain parliamentary approval of an agreed withdrawal agreement may, absent a revocation of the U.K.'s notification to withdraw or some other further delay, mean that the U.K. would leave the EU on October 31, 2019 with no agreement (a so-called "hard Brexit"). Absent delay or mitigating legislative measures by individual EU Member States, in the event of a hard Brexit the trade relationship between the U.K. and the EU would be solely based on World Trade Organization terms, thereby hindering current levels of mutual market access.

        If the U.K. and the EU do reach a deal on or before October 31, 2019 (or any later withdrawal date which may subsequently be agreed between the U.K. and the EU) or if the U.K.'s withdrawal takes effect on the terms of the existing withdrawal agreement, a transition period may start that lasts until December 31, 2020. Based upon the currently proposed transition plan, during this period, the U.K. would, with some exceptions, remain subject to EU law. It would also maintain access to the EU's single market. During this transition phase, the U.K. and EU would also start negotiations on their future trade relationship.

        The consequences for the economies of the U.K. and the EU member states as a result of the U.K.'s withdrawal from the EU are unknown and unpredictable, especially in the case of a hard Brexit. Given the lack of comparable precedent, it is unclear what the broader macro-economic and financial implications the U.K. leaving the EU with no agreements in place would have.

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        Since a significant proportion of the regulatory framework in the U.K. is derived from EU directives and regulations, Brexit could materially impact the regulatory regime with respect to the approval of our product candidates in the U.K. or the EU. Any delay in obtaining, or an inability to obtain, any marketing approvals, as a result of Brexit or otherwise, would prevent us from commercializing our product candidates in the U.K. and/or the EU and restrict our ability to generate revenue and achieve and sustain profitability. If any of these outcomes occur, we may be forced to restrict or delay efforts to seek regulatory approval in the U.K. and/or EU for our product candidates, which could significantly and materially harm our business.

We, or any future collaborators, may not be able to obtain or maintain orphan drug exclusivity for our product candidates and, even if we do, that exclusivity many not prevent the FDA or the European Commission from approving competing products.

        Regulatory authorities in some jurisdictions, including the United States and the EU, may designate drugs for relatively small patient populations as orphan drugs. Under the Orphan Drug Act, the FDA may designate a product as an orphan drug if it is a drug intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals annually in the United States, or a patient population greater than 200,000 in the United States where there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States. APR-246 has received orphan drug designation from the FDA for use in the treatment of high-risk myelodysplastic syndromes, or MDS, and orphan drug designation from the EMA for MDS, acute myeloid leukemia, or AML, and ovarian cancer. We may seek orphan drug designations for APR-246 for other indications or for other of our product candidates. There can be no assurances that we will be able to obtain such designations.

        In the United States, orphan drug designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers. In addition, the company that obtains the first FDA approval for a designated orphan drug for a rare disease receives marketing exclusivity for use of that drug for the designated condition for a period of seven years. Once a product receives orphan drug exclusivity, a second product that is considered to be the same drug for the same indication generally may be approved during the exclusivity period only if the second product is shown to be "clinically superior" to the original orphan drug in that it is more effective, safer or otherwise makes a "major contribution to patient care" or the holder of exclusive approval cannot assure the availability of sufficient quantities of the orphan drug to meet the needs of patients with the disease or condition for which the drug was designated.

        The European Commission can grant orphan drug product designation to products for which the sponsor can establish that it is intended for the diagnosis, prevention, or treatment of (1) a life-threatening or chronically debilitating condition affecting not more than five in 10,000 people in the European Union, or (2) a life threatening, seriously debilitating or serious and chronic condition in the European Union and that without incentives it is unlikely that sales of the drug in the European Union would generate a sufficient return to justify the necessary investment. In addition, it must be established that there is no other satisfactory method approved in the European Union of diagnosing, preventing or treating the condition, or if such a method exists, the proposed orphan drug will be of significant benefit to patients. Orphan drug designation is not a marketing authorization. It is a designation that provides a number of benefits, including fee reductions, regulatory assistance, and the possibility to apply for a centralized EU marketing authorization, as well as 10 years of market exclusivity following a marketing authorization. During this market exclusivity period, neither the EMA, nor the European Commission nor the EU member states can accept an application or grant a marketing authorization for a 'similar medicinal product.' A 'similar medicinal product' is defined as a medicinal product containing a similar active substance or substances as contained in an authorized orphan medicinal product, and which is intended for the same therapeutic indication. The market

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exclusivity period for the authorized therapeutic indication may be reduced to six years if, at the end of the fifth year, it is established that the orphan designation criteria are no longer met, including where it is shown that the product is sufficiently profitable not to justify maintenance of market exclusivity. In addition, a competing similar medicinal product may in limited circumstances be authorized prior to the expiration of the market exclusivity period, including if it is shown to be safer, more effective or otherwise clinically superior to our product. Our product can lose orphan designation, and the related benefits, prior to us obtaining a marketing authorization if it is demonstrated that the orphan designation criteria are no longer met.

        Even if we, or any future collaborators, obtain orphan drug designation for a product candidate, we, or they, may not be able to obtain or maintain orphan drug exclusivity for that product candidate. We may not be the first to obtain marketing approval of any product candidate for which we have obtained orphan drug designation for the orphan-designated indication due to the uncertainties associated with developing drug products. If this happens, marketing approval for our product candidate may be delayed due to the first-approved product's orphan drug exclusivity, unless we demonstrate clinical superiority. We may not be able to demonstrate that our product is clinically superior to a first-approved product with orphan drug exclusivity, i.e., that it provides greater safety or efficacy or a major contribution to patient care. In addition, exclusive marketing rights in the United States may be limited if we seek approval for an indication broader than the orphan-designated indication or may be lost if the FDA later determines that the request for designation was materially defective or if we are unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition. Further, even if we, or any future collaborators, obtain orphan drug exclusivity for a product, that exclusivity may not effectively protect the product from competition because different drugs with different active moieties may be approved for the same condition. Even after an orphan drug is approved, the FDA can subsequently approve the same drug with the same active moiety for the same condition if the FDA concludes that the later drug is clinically superior in that it is shown to be safer, more effective or makes a major contribution to patient care or the manufacturer of the product with orphan exclusivity is unable to maintain sufficient product quantity. Orphan drug designation neither shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process.

Even if we, or any collaborators we may have in the future, obtain marketing approvals for our product candidates, the terms of approvals and ongoing regulation of our product candidates could require substantial expenditure of resources and may limit how we, or they, manufacture and market our product candidates, which could materially impair our ability to generate revenue.

        Once marketing approval has been granted, an approved drug and its manufacturer and marketer are subject to ongoing review and extensive regulation. These requirements include submissions of safety and other post-marketing information and reports, user fee requirements, registration and listing requirements, requirements relating to manufacturing, quality control, quality assurance and corresponding maintenance of records and documents, requirements regarding the distribution of samples to physicians and recordkeeping. We, and any collaborators we may have in the future, must also comply with requirements concerning advertising and promotion for any of our product candidates for which we or they obtain marketing approval. Promotional communications with respect to prescription drugs are subject to a variety of legal and regulatory restrictions and must be consistent with the information in the drug's approved labeling. Thus, we, and any collaborators we may have in the future, may not be able to promote any drugs we develop for indications or uses for which they are not approved.

        The FDA or comparable foreign regulatory authorities may also impose requirements for costly post-marketing studies or clinical trials and surveillance to monitor the safety or efficacy of a drug. For example, the approval may be subject to limitations on the indicated uses for which the drug may be

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marketed or to the conditions of approval, including the requirement to implement a REMS or comparable foreign equivalents, like the EU Risk Management Plan, or RMP, which could include requirements for a restricted distribution system. Manufacturers of approved drugs and those manufacturers' facilities are also required to comply with extensive FDA or comparable foreign regulatory authorities requirements, including ensuring that quality control and manufacturing procedures conform to cGMPs, which include requirements relating to quality control and quality assurance as well as the corresponding maintenance of records and documentation and reporting requirements. We, our contract manufacturers, our future collaborators and their contract manufacturers could be subject to periodic unannounced inspections by the FDA or comparable foreign regulatory authorities to monitor and ensure compliance with cGMPs.

        Accordingly, assuming we, or our future collaborators, receive marketing approval for one or more of our product candidates, we, and our future collaborators, and our and their contract manufacturers will continue to expend time, money and effort in all areas of regulatory compliance, including manufacturing, production, product surveillance and quality control.

        If we, and our future collaborators, are not able to comply with post-approval regulatory requirements, regulatory agencies or enforcement authorities may:

    issue warning letters;

    impose civil or criminal penalties;

    suspend regulatory approval;

    suspend any of our ongoing clinical trials;

    refuse to approve pending applications or supplements to approved applications submitted by us or our collaborators;

    impose restrictions on our operations, including closing our or our collaborators' manufacturing facilities; or

    seize or detain products or require a recall.

        Any government investigation of alleged violations of law could require us to expend significant time and resources in response and could generate negative publicity. Any failure to comply with ongoing regulatory requirements may significantly and adversely affect our ability to commercialize and generate revenue from our product candidates, if approved. If regulatory sanctions are applied or if regulatory approval is withdrawn, the value of our company and our operating results will be adversely affected.

        The regulatory requirements and policies may change, and additional government regulations may be enacted for which we may also be required to comply. We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the United States or in other countries. If we or any future collaboration partner are not able to maintain regulatory compliance, we or such collaboration partner, as applicable, may face government enforcement action and our business will suffer. Moreover, our or our future collaborators' ability to market any future drugs could be limited, which could adversely affect our ability to achieve or sustain profitability. Further, the cost of compliance with post-approval regulations may have a negative effect on our operating results and financial condition.

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The FDA's and other comparable regulatory authorities' policies may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our product candidates, which would impact our ability to generate revenue.

        In December 2016, the 21st Century Cures Act, or Cures Act, was signed into law. The Cures Act, among other things, is intended to modernize the regulation of drugs and spur innovation, but its ultimate implementation is unclear. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained and we may not achieve or sustain profitability, which would adversely affect our business, prospects, financial condition and results of operations.

        We also cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad. For example, certain policies of the Trump administration may impact our business and industry. Namely, the Trump administration has taken several executive actions, including the issuance of a number of Executive Orders, that could impose significant burdens on, or otherwise materially delay, the FDA's ability to engage in routine regulatory and oversight activities such as implementing statutes through rulemaking, issuance of guidance, and review and approval of marketing applications. Notably, on January 30, 2017, President Trump issued an Executive Order, applicable to all executive agencies, including the FDA, that requires that for each notice of proposed rulemaking or final regulation to be issued in fiscal year 2017, the agency shall identify at least two existing regulations to be repealed, unless prohibited by law. These requirements are referred to as the "two-for-one" provisions. This Executive Order includes a budget neutrality provision that requires the total incremental cost of all new regulations in the 2017 fiscal year, including repealed regulations, to be no greater than zero, except in limited circumstances. For fiscal years 2018 and beyond, the Executive Order requires agencies to identify regulations to offset any incremental cost of a new regulation and approximate the total costs or savings associated with each new regulation or repealed regulation. In interim guidance issued by the Office of Information and Regulatory Affairs, within the Office of Management and Budget, on February 2, 2017, the administration indicates that the "two-for-one" provisions may apply not only to agency regulations, but also to significant agency guidance documents. In addition, on February 24, 2017, President Trump issued an Executive Order directing each affected agency to designate an agency official as a "Regulatory Reform Officer" and establish a "Regulatory Reform Task Force" to implement the two-for-one provisions and other previously issued Executive Orders relating to the review of federal regulations; however, it is difficult to predict how these requirements will be implemented, and the extent to which they will impact the FDA's ability to exercise its regulatory authority. If these executive actions impose constraints on FDA's ability to engage in oversight and implementation activities in the normal course, our business may be negatively impacted.

Any of our product candidates for which we, or our future collaborators, obtain marketing approval in the future will be subject to substantial penalties if we, or they, fail to comply with regulatory requirements or if we, or they, experience unanticipated problems with our product candidates following approval.

        Any of our product candidates for which we, or our future collaborators, obtain marketing approval in the future, will be subject to continual review by the FDA or comparable foreign regulatory authorities.

        For example in the United States, the FDA and other agencies, including the Department of Justice, or the DOJ, closely regulate and monitor the post-approval marketing and promotion of drugs to ensure that they are manufactured, marketed and distributed only for the approved indications and in accordance with the provisions of the approved labeling. The FDA imposes stringent restrictions on manufacturers' communications regarding off-label use and if we, or our future collaborators, do not market any of our product candidates for which we, or they, receive marketing approval for only their

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approved indications, we, or they, may be subject to warnings or enforcement action for off-label marketing. Violation of the FDCA and other statutes, including the False Claims Act, relating to the promotion and advertising of prescription drugs may lead to investigations or allegations of violations of federal and state healthcare fraud and abuse laws and state consumer protection laws.

        In addition, later discovery of previously unknown adverse events or other problems with our product candidates or their manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may yield various results, including:

    litigation involving patients taking our drug;

    restrictions on such drugs, manufacturers or manufacturing processes;

    restrictions on the labeling or marketing of a drug;

    restrictions on drug distribution or use;

    requirements to conduct post-marketing studies or clinical trials;

    warning letters or untitled letters;

    withdrawal of the drugs from the market;

    refusal to approve pending applications or supplements to approved applications that we submit;

    recall of drugs;

    fines, restitution or disgorgement of profits or revenues;

    suspension or withdrawal of marketing approvals;

    damage to relationships with any potential collaborators;

    restrictions on coverage by third-party payors;

    unfavorable press coverage and damage to our reputation;

    refusal to permit the import or export of drugs;

    drug seizure; or

    injunctions or the imposition of civil or criminal penalties.

Recently enacted and future legislation, and a change in existing government regulations and policies, may increase the difficulty and cost for us and our future collaborators to obtain marketing approval of and commercialize our product candidates and affect the prices we, or they, may obtain.

        In the United States and some foreign jurisdictions, there have been and continue to be a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our product candidates, restrict or regulate post-approval activities and affect our ability, or the ability of our future collaborators, to profitably sell any drugs for which we, or they, obtain marketing approval. We expect that current laws, as well as other healthcare reform measures that may be adopted in the future, may result in more rigorous coverage criteria and additional downward pressure on the price that we, or our future collaborators, may receive for any approved drugs.

        In the United States, the Congress and recent presidential administrations have enacted or are considering a number of legislative and regulatory proposals to change the healthcare system in ways that could affect our ability to sell our products, if approved, and to do so profitably. Among policy makers and payors in the United States and elsewhere, there is significant interest in promoting

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changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and expanding access.

        In the United States, the pharmaceutical industry has been a particular focus of efforts to reform the healthcare system and has been significantly affected by major legislative initiatives, including the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act (collectively, "PPACA"), which contains provisions that may potentially affect the profitability of our products, including, for example, increased rebates for products sold to Medicaid programs, extension of Medicaid rebates to Medicaid managed care plans, mandatory discounts for certain Medicare Part D beneficiaries and annual fees based on pharmaceutical companies' share of sales to federal health care programs, and expansion of the entities eligible for discounts under the Public Health Services pharmaceutical pricing program. There have been judicial and Congressional challenges to the PPACA, as well as efforts by the Trump administration to repeal or replace certain aspects of the PPACA that contribute to regulatory uncertainty that could affect the profitability of our products. Since January 2017, President Trump has signed several Executive Orders and other directives designed to delay the implementation of certain provisions of the PPACA or otherwise circumvent some of the requirements mandated by the PPACA. In December 2018, a federal district court in Texas ruled the individual mandate was unconstitutional and could not be severed from the PPACA. As a result, the court ruled the remaining provisions of the PPACA were also invalid, though the court declined to issue a preliminary injunction with respect to the PPACA. In April 2019, in a brief filed in the Fifth Circuit Court of Appeals, the Trump Administration took the position that the individual mandate was unconstitutional, that it could not be severed from the PPACA, and, as a result, the PPACA must be invalidated in its entirety. The case is pending before the Fifth Circuit, and it remains unclear whether, and to what extent, the PPACA may be affected by the Fifth Circuit's and possibly other courts' rulings.

        While Congress has not enacted legislation to comprehensively repeal the PPACA, at least two bills affecting the implementation of the PPACA have been signed into law, including the repeal, effective January 1, 2019, of the tax-based shared responsibility payment imposed by the PPACA on certain individuals who fail to maintain qualifying health coverage for all or part of a year, which is commonly referred to as the "individual mandate." Additionally, on January 22, 2018, President Trump signed a continuing resolution on appropriations for fiscal year 2018 that delayed the implementation of certain fees mandated by the PPACA, including the so-called "Cadillac" tax on certain high-cost employer-sponsored health insurance plans and the annual fee imposed on certain health insurance providers. Moreover, effective January 1, 2019, the Bipartisan Budget Act of 2018, among other things, further amends portions of the Social Security Act implemented as part of the PPACA to increase from 50% to 70% the point-of-sale discount that pharmaceutical manufacturers participating in the Coverage Gap Discount Program provide to eligible Medicare Part D beneficiaries during the coverage gap phase of the Part D benefit, commonly referred to as the "donut hole," and to reduce standard beneficiary cost sharing in the coverage gap from 30% to 25% in most Medicare Part D plans. In the future, there may be additional challenges and/or amendments to the PPACA. It remains to be seen precisely what any new legislation will provide, when or if it will be enacted, and what impact it will have on the availability and cost of healthcare items and services, including drug products.

        Other legislative changes have been proposed and adopted since PPACA was enacted. These changes include the Budget Control Act of 2011, which, among other things, led to aggregate reductions in Medicare payments to providers of up to 2% per fiscal year that started in April 2013 and, due to subsequent statutory amendments, will continue through 2027 unless additional Congressional action is taken. The American Taxpayer Relief Act of 2012, which, among other changes, reduced Medicare payments to several types of providers and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. These legislative changes may result in additional reductions in Medicare and other healthcare funding and otherwise affect the prices we may obtain for any of our product candidates for which we may obtain regulatory approval or the frequency with which any such product candidate is prescribed or used.

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        More recently, the cost of prescription pharmaceuticals has been the subject of considerable discussion in the United States. Congress has begun developing legislation and the Trump Administration has proposed and begun implementing regulatory reforms to further increase transparency around prices and price increases, lower out-of-pocket costs for consumers, and decrease spending on prescription drugs by government programs. Congress has conducted or is in the process of conducting inquiries into the prescription drug industry's pricing practices. The Trump Administration's budget proposal for fiscal year 2019 contained additional drug price control measures that could be enacted in future legislation, including, for example, measures to end Medicare Part B coverage of medications and to shift those medication costs to Medicare Part D, to allow some states to negotiate prescription drug prices under Medicaid and to eliminate cost sharing for generic drugs for low-income patients. While several proposed reform measures will require Congress to pass legislation to become effective, Congress and the Trump Administration have each indicated that it will continue to seek new legislative and/or regulatory measures to address prescription drug costs. At the state level, legislatures are increasingly passing legislation and states are implementing regulations designed to control spending on, and patient out-of-pocket costs for, drug products. Implementation of cost containment measures or other healthcare reforms that affect the pricing and/or availability of drug products may impact our ability to generate revenue, attain or maintain profitability, or commercialize products for which we may receive regulatory approval in the future.

        We expect that these and other healthcare reform measures that may be adopted in the future may result in more rigorous coverage criteria and/or new payment methodologies, and place additional downward pressure on the price that we receive for any approved product and/or the level of reimbursement physicians receive for administering any approved product we might bring to market. Reductions in reimbursement levels and imposition of more rigorous coverage criteria or new payment methodologies may negatively impact the prices we receive or the frequency with which our products are prescribed or administered. Any coverage or reimbursement policies instituted by Medicare or other federal health care programs may result in a similar policies from private payors. The implementation of cost containment measures or other healthcare reforms may affect our ability to generate revenue, attain or maintain profitability, or commercialize our product candidates. We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services, which could result in reduced demand for our product candidates or additional pricing pressures.

        The pricing of prescription pharmaceuticals is also subject to governmental control outside the United States. In these countries, pricing negotiations with governmental authorities can take considerable time after the receipt of marketing approval for a product. To obtain reimbursement or pricing approval in some countries, we may be required to conduct a clinical trial that compares the cost-effectiveness of our product candidates to that of other available therapies. If reimbursement of our products is unavailable or limited in scope or amount, or if pricing is set at unsatisfactory levels, our ability to generate revenues and become profitable could be impaired.

        Legislative and regulatory proposals have also been made to expand post-approval requirements and restrict sales and promotional activities for drug products. We cannot be sure whether additional legislative changes will be enacted, or whether the FDA regulations, guidance or interpretations will be changed, or what the impact of such changes on the marketing approvals of our product candidates, if any, may be. In addition, increased scrutiny by the United States Congress of the FDA's approval process may significantly delay or prevent marketing approval, as well as subject us and any future collaborators to more stringent drug labeling and post-marketing testing and other requirements.

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We may seek a breakthrough therapy designation for APR-246 or one or more of our other product candidates, but we might not receive such designation, and even if we do, such designation may not lead to a faster development or regulatory review or approval process.

        We may seek a breakthrough therapy designation for APR-246 or one or more of our other product candidates. A breakthrough therapy is defined as a drug that is intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening condition, and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. For drugs and biologics that have been designated as breakthrough therapies, interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens. Drugs designated as breakthrough therapies by the FDA may also be eligible for priority review if supported by clinical data at the time the NDA is submitted to the FDA, and parts of the NDA may be submitted and reviewed on a rolling basis.

        Designation as a breakthrough therapy is within the discretion of the FDA. Accordingly, even if we believe that one of our product candidates meets the criteria for designation as a breakthrough therapy, the FDA may disagree and instead determine not to make such designation. Even if we receive breakthrough therapy designation, the receipt of such designation for a product candidate may not result in a faster development or regulatory review or approval process compared to drugs considered for approval under conventional FDA procedures and does not assure ultimate approval by the FDA. In addition, even if one or more of our product candidates qualify as breakthrough therapies, the FDA may later decide that the product candidates no longer meet the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

A fast track designation by the FDA for APR-246 may not actually lead to a faster development or regulatory review or approval process.

        If a drug is intended, whether alone or in combination with one or more other drugs, for the treatment of a serious or life-threatening condition and nonclinical or clinical data demonstrate the potential to address unmet medical need for this condition, a drug sponsor may apply for FDA fast track designation. Although we have received a fast track designation for APR-246 for the treatment of patients with myelodysplastic syndrome having a TP53 mutation, this does not ensure that we will receive marketing approval or that approval will be granted within any particular timeframe. We may not experience a faster development or regulatory review or approval process with fast track designation compared to conventional FDA procedures. In addition, the FDA may withdraw fast track designation if it believes that the designation is no longer supported by data from our clinical development program. Fast track designation alone does not guarantee qualification for the FDA's priority review procedures.

We may seek priority review designation for APR-246 or one or more of our other product candidates, but we might not receive such designation, and even if we do, such designation may not lead to a faster development or regulatory review or approval process.

        If the FDA determines that a product candidate offers a treatment for a serious condition and, if approved, the product would provide a significant improvement in safety or effectiveness, the FDA may designate the product candidate for priority review. A priority review designation means that the goal for the FDA to review an application is six months from the 60-day filing date, rather than the standard review period of ten months. We may request priority review for our product candidates. The FDA has broad discretion with respect to whether or not to grant priority review status to a product candidate, so even if we believe a particular product candidate is eligible for such designation or status, the FDA may decide not to grant it. Moreover, a priority review designation does not necessarily mean

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a faster development or regulatory review or approval process or necessarily confer any advantage with respect to approval compared to conventional FDA procedures. Receiving priority review from the FDA does not guarantee approval within the six-month review cycle or at all.

Our relationships with healthcare providers, physicians and third-party payors will be subject to applicable anti-kickback, fraud and abuse and other healthcare laws and regulations, which could expose us to penalties, including criminal sanctions, civil penalties, contractual damages, reputational harm and diminished profits and future earnings.

        Although we do not currently have any products on the market, we are subject to a variety of regulatory requirements, including healthcare statutory and regulatory requirements and enforcement by the U.S. federal and state governments and the foreign governments of the countries in which we conduct our business. Even though we are not in a position to make patient referrals and do not bill Medicare, Medicaid, or other government or commercial third-party payers, our relationships with healthcare providers, physicians and third-party payors will subject us to healthcare statutory and regulatory requirements and enforcement by the federal government and the states and foreign governments in which we conduct our business. Our future arrangements with healthcare providers, physicians and third-party payors and patients may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships through which we market, sell and distribute our products for which we obtain marketing approval. Restrictions under applicable federal and state healthcare laws and regulations include, without limitation, the following:

    The Federal Anti-Kickback Statute—An intent-based federal criminal statute that prohibits, among other things, any person from knowingly and willfully soliciting, offering, receiving or paying remuneration, directly or indirectly, in cash or in kind, to induce or reward, or in return for, either the referral of an individual for, or the purchase, order or recommendation or arranging of, any good or service, for which payment may be made, in whole or in part, by a federal health care program, such as Medicare and Medicaid. The term "remuneration" has been broadly interpreted to include anything of value. The PPACA, among other things, amended the intent requirement of the federal Anti-Kickback Statute, so that a person or entity no longer needs to have actual knowledge of this statute or specific intent to violate it. The Anti-Kickback Statute has also been interpreted to apply to arrangements between pharmaceutical manufacturers on the one hand and individuals, such as prescribers, patients, purchasers, and formulary managers on the other the other hand. A conviction for violation of the Anti-Kickback Statute results in criminal fines and requires mandatory exclusion from participation in federal health care programs. Although there are a number of statutory exceptions and regulatory safe harbors to the federal Anti-Kickback Statute that protect certain common industry practices from prosecution, the exceptions and safe harbors are narrowly drawn, and arrangements may be subject to scrutiny or penalty if they do not fully satisfy all elements of an available exception or safe harbor. The Anti-Kickback Statute safe harbors, including the discount safe harbor, are the subject of possible regulatory reforms. Any changes to the safe harbors may impact our future contractual and other arrangements with pharmacy benefit managers, third-party payors, wholesalers and distributors, healthcare providers and prescribers, and other entities, as well as our future pricing strategies.

    The Federal Civil False Claims Act—Imposes civil penalties, including through civil whistleblower or qui tam actions, against individuals or entities for, among other things, knowingly presenting, or causing to be presented, false or fraudulent claims for payment by a federal healthcare program or knowingly making using or causing to be made or used a false statement or record material to payment of a false claim or avoiding, decreasing or concealing an obligation to pay money to the federal government, with potential liability including mandatory treble damages

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      and significant per-claim penalties, currently set at $11,181 to $22,363 per false claim or statement for penalties assessed after January 29, 2018, with respect to violations occurring after November 2, 2015. Among other reasons, pharmaceutical companies have been investigated and/or subject to government enforcement actions asserting liability under the federal civil False Claims Act in connection with their alleged off-label promotion of drugs, purportedly concealing price concessions in the pricing information submitted to the government for government price reporting purposes (e.g., under the Medicaid Drug Rebate Program), and allegedly providing free product to customers with the expectation that the customers would bill federal health care programs for the product. In addition, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the federal False Claims Act. As a result of a modification made by the Fraud Enforcement and Recovery Act of 2009, a claim includes "any request or demand" for money or property presented to the U.S. government. In addition, manufacturers can be held liable under the federal False Claims Act even when they do not submit claims directly to government payors if they are deemed to "cause" the submission of false or fraudulent claims. Criminal prosecution is also possible for making or presenting a false, fictitious or fraudulent claim to the federal government.

    The Federal Criminal Statute on False Statements Relating to Health Care Matters—Makes it a crime to knowingly and willfully falsify, conceal, or cover up a material fact, make any materially false, fictitious, or fraudulent statements or representations, or make or use any materially false writing or document knowing the same to contain any materially false, fictitious, or fraudulent statement or entry in connection with the delivery of or payment for federally funded healthcare benefits, items, or services.

    HIPAA Criminal Federal Health Care Fraud Statute—Enacted as part of the Health Insurance Portability and Accountability Act of 1996, makes it a crime to knowingly and willfully falsify, conceal, or cover up a material fact, make any materially false, fictitious, or fraudulent statements or representations, or make or use any materially false writing or document knowing the same to contain any materially false, fictitious, or fraudulent statement or entry in connection with the delivery of or payment for federally funded healthcare benefits, items, or services.

    The Federal Civil Monetary Penalties Law—Authorizes the imposition of substantial civil monetary penalties against an entity, such as a pharmaceutical manufacturer, that engages in activities including, among others (1) knowingly presenting, or causing to be presented, a claim for services not provided as claimed or that is otherwise false or fraudulent in any way; (2) arranging for or contracting with an individual or entity that is excluded from participation in federal healthcare programs to provide items or services reimbursable by a federal healthcare program; (3) violations of the federal Anti-Kickback Statute; or (4) failing to report and return a known overpayment.

    HIPAA Health Information Privacy and Security—The Health Insurance Portability and Accountability Act of 1996, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009, or HITECH, and its implementing regulations, or collectively, HIPAA, imposes privacy, security, and breach reporting obligations on certain covered entity healthcare providers, health plans, and healthcare clearinghouse as well as their business associates that perform certain services involving the use or disclosure of individually identifiable health information, including, among other requirements, mandatory contractual terms and technical safeguards to protect the privacy, security and transmission of individually identifiable health information, and require notification to affected individuals and regulatory authorities of certain breaches of security of individually identifiable health information. HITECH also created new tiers of civil monetary penalties, amended HIPAA to make civil and criminal penalties

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      directly applicable to business associates, and gave state attorneys general new authority to file civil actions for damages or injunctions in U.S. federal courts to enforce the federal HIPAA laws and seek attorneys' fees and costs associated with pursuing federal civil actions.

    The Federal Physician Payments Sunshine Act—Requires "applicable manufacturers" of drugs, devices, biologics, and medical supplies for which payment is available under Medicare, Medicaid or the State Children's Health Insurance Program, among others, to track and report annually to the federal government (for disclosure to the public) certain payments and other transfers of value they make to "covered recipients." The term covered recipients includes physicians, teaching hospitals, and, for reports submitted on or after January 1, 2022, physician assistants, nurse practitioners, clinical nurse specialists, certified nurse anesthetists, and certified nurse midwives. Failure to submit required information may result in civil monetary penalties.

    The Federal Food, Drug, and Cosmetic Act—Prohibits, among other things, the adulteration or misbranding of drugs, biologics and medical devices.

    Analogous State and Foreign Laws—There are state and foreign law equivalents of the above federal laws, such as the Anti-Kickback Statute and the False Claims Act, which may apply to items or services reimbursed by any third-party payor, including commercial insurers (i.e., so-called "all-payor anti-kickback laws"). Similarly, there are state and foreign laws that govern the privacy and security of health information, biometric information or more general personally identifiable information, including state health information privacy laws, data breach notification laws, marketing privacy laws, and certain comprehensive privacy legislation such as the new California Consumer Privacy Act which govern the collection, use, disclosure, and protection of health-related and other personal information, many of which differ from each other in significant ways and, with respect to state laws, are often not pre-empted by HIPAA, or govern data that we may have that is outside the scope of HIPAA, thus requiring additional compliance efforts. These privacy and data protection laws are also evolving, requiring continual evaluation and investment in compliance programs.

    State and Foreign Laws Regulating Pharmaceutical Manufacturer Compliance Programs and Other Practices—Some state and foreign laws require pharmaceutical companies to implement compliance programs, comply with the pharmaceutical industry's voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government, or to track and report gifts, compensation, or other remuneration to physicians and other healthcare providers. Several U.S. states and localities have enacted legislation requiring pharmaceutical companies to establish marketing compliance programs, file periodic reports, and/or make periodic public disclosures on sales, marketing, pricing, clinical trials, and other activities. Other state laws prohibit certain marketing-related activities including the provision of gifts, meals or other items to certain healthcare providers, and restrict the ability of manufacturers to offer co-pay support to patients for certain prescription drugs. In addition, several recently passed state laws require disclosures related to state agencies and/or commercial purchasers with respect to certain price increases that exceed a certain level as identified in the relevant statutes. Some of these laws and regulations contain ambiguous requirements that government officials have not yet clarified. Given the lack of clarity in the laws and their implementation, our reporting actions could be subject to the penalty provisions of the pertinent federal and state laws and regulations.

        Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that our business practices may not comply with current or future statutes, regulations, guidance, case law or other applicable law. If our operations are found to be in violation of any of these laws or any other governmental regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, individual imprisonment, exclusion from

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participation in federal health care programs, such as Medicare and Medicaid, disgorgement, reputational harm, additional oversight and reporting obligations pursuant to a corporate integrity agreement or similar agreement to resolve allegations of non-compliance with applicable laws and regulations, and the curtailment or restructuring of our operations, any of which could adversely affect our ability to market our products, if approved, and adversely impact our financial results. Although effective compliance programs can mitigate the risk of investigation and prosecution for violations of these laws and regulations, these risks cannot be entirely eliminated. Any action against us for an alleged or suspected violation could cause us to incur significant legal expenses and could divert our management's attention from the operation of our business, even if our defense is successful. If any of the physicians or other healthcare providers or entities with whom we expect to do business is found not to be in compliance with applicable laws, it may be costly to us in terms of money, time and resources, and they may be subject to criminal, civil or administrative sanctions, including exclusions from government-funded healthcare programs.

Our employees may engage in misconduct or other improper activities, including non-compliance with regulatory standards and requirements, which could cause significant liability for us and harm our reputation.

        We are exposed to the risk of employee fraud or other misconduct, including intentional failures to comply with FDA regulations or similar regulations of comparable foreign regulatory authorities, provide accurate information to the FDA or comparable foreign regulatory authorities, comply with manufacturing standards we may establish, comply with federal and state healthcare fraud and abuse laws and regulations and similar laws and regulations established and enforced by comparable foreign regulatory authorities, report financial information or data accurately or disclose unauthorized activities to us. In particular, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, incentive programs and other business arrangements. Employee misconduct could also involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. It is not always possible to identify and deter employee misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws, standards or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and results of operations, including the imposition of significant fines or other sanctions.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could have a material adverse effect on our business.

        We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals and biological materials. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury from these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties.

        Although we maintain workers' compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials, this insurance

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may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of hazardous and flammable materials, including chemicals and biological materials.

        In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or commercialization efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

Laws and regulations governing any international operations we may have in the future may preclude us from developing, manufacturing and selling certain product candidates outside of the United States and require us to develop and implement costly compliance programs.

        If we expand our operations outside of the United States, we must comply with numerous laws and regulations in each jurisdiction in which we plan to operate, such as the applicable anti-bribery, anti-corruption, anti-money laundering regulations. The creation and implementation of international business practices compliance programs is costly and such programs are difficult to enforce, particularly where reliance on third parties is required.

        The Foreign Corrupt Practices Act, or FCPA, prohibits any U.S. individual or business from paying, offering, authorizing payment or offering of anything of value, directly or indirectly, to any foreign official, political party or candidate for the purpose of influencing any act or decision of the foreign entity in order to assist the individual or business in obtaining or retaining business. The FCPA also obligates companies whose securities are listed in the United States to comply with certain accounting provisions requiring the company to maintain books and records that accurately and fairly reflect all transactions of the corporation, including international subsidiaries, and to devise and maintain an adequate system of internal accounting controls for international operations. The anti-bribery provisions of the FCPA are enforced primarily by the DOJ. The Securities and Exchange Commission, or SEC, is involved with enforcement of the books and records provisions of the FCPA.

        Compliance with the FCPA is expensive and difficult, particularly in countries in which corruption is a recognized problem. In addition, the FCPA presents particular challenges in the pharmaceutical industry, because, in many countries, hospitals are operated by the government, and doctors and other hospital employees are considered foreign officials. Certain payments to hospitals in connection with clinical trials and other work have been deemed to be improper payments to government officials and have led to FCPA enforcement actions.

        Violation of the FCPA can result in significant civil and criminal penalties. Indictment alone under the FCPA can lead to suspension of the right to do business with the U.S. government until the pending claims are resolved. Conviction of a violation of the FCPA can result in long-term disqualification as a government contractor. The termination of a government contract or relationship as a result of our failure to satisfy any of our obligations under laws governing international business practices would have a negative impact on our operations and harm our reputation and ability to procure government contracts. The SEC also may suspend or bar issuers from trading securities on U.S. exchanges for violations of the FCPA's accounting provisions.

        We are also subject to other laws and regulations governing our international operations, including applicable import and export control regulations, economic sanctions on countries and persons administered or enforced by the U.S. government (including, without limitation, the Office of Foreign Assets Control of the U.S. Department of the Treasury), anti-money laundering laws, customs requirements and currency exchange regulations, collectively referred to as the trade control laws. We can provide no assurance that we will be completely effective in ensuring our compliance with all applicable legal requirements, including trade control laws. If we are not in compliance with applicable trade control laws, we may be subject to criminal and civil penalties, disgorgement and other sanctions

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and remedial measures, and legal expenses, which could have an adverse impact on our business, results of operations, financial condition and prospects. Likewise, any investigation of any potential violations of these trade control laws by U.S. or other authorities could also have an adverse impact on our reputation, our business, results of operations, financial condition and prospects.

        Various laws, regulations and executive orders also restrict the use and dissemination outside of the United States, or the sharing with certain non-U.S. nationals, of information classified for national security purposes, as well as certain products and technical data relating to those products. If we expand our presence outside of the United States, it will require us to dedicate additional resources to comply with these laws, and these laws may preclude us from developing, manufacturing, or selling certain drugs and product candidates outside of the United States, which could limit our growth potential and increase our development costs. The failure to comply with laws governing international business practices may result in substantial penalties, including suspension or debarment from government contracting.

Security breaches, loss of data and other disruptions could compromise sensitive information related to our business or prevent us from accessing critical information and expose us to liability, which could adversely affect our business and our reputation.

        In the ordinary course of our business, we collect and store sensitive data, including personally identifiable information, intellectual property and proprietary business information owned or controlled by ourselves and other parties. We manage and maintain our applications and data utilizing a combination of on-site systems, managed data centers and cloud-based data centers. We utilize external security and infrastructure vendors to manage our information technology systems and data centers. These applications and data encompass a wide variety of business-critical information, including research and development information, commercial information, and business and financial information. We face a number of risks relative to protecting this critical information, including loss of access risk, inappropriate use or disclosure, inappropriate modification, and the risk of our being unable to adequately monitor, audit and modify our controls over our critical information. This risk extends to the third-party vendors and subcontractors we use to manage this sensitive data.

        The secure processing, storage, maintenance and transmission of this critical information are vital to our operations and business strategy. Although we take measures to protect sensitive data from unauthorized access, use or disclosure, and are in the process of developing policies and procedures to protect our information technology systems and confidential and proprietary information, we do not currently have any such policies and procedures formally in place and our information technology and infrastructure may be vulnerable to attacks by hackers or viruses or breached due to employee error, malfeasance or other malicious or inadvertent disruptions. Any such breach or interruption could compromise our networks and the information stored there could be accessed by unauthorized parties, manipulated, publicly disclosed, lost or stolen. Any such access, breach or other loss of information could result in legal claims or proceedings, and liability under federal or state laws that protect the privacy of personal information, such as the Health Insurance Portability and Accountability Act of 1996, or HIPAA, the Health Information Technology for Economic and Clinical Health Act, or HITECH, and regulatory penalties. Notice of breaches must be made to affected individuals, the Secretary of the Department of Health and Human Services, and for extensive breaches, notice may need to be made to the media or State Attorneys General. Such a notice could harm our reputation and our ability to compete. Although we have implemented security measures and are in the process of implementing formal, dedicated enterprise policies and procedures to prevent unauthorized access to patient data, we do not currently have any such policies and procedures formally in place and there is no guarantee we can protect our data from breach. Unauthorized access, loss or dissemination could also damage our reputation or disrupt our operations, including our ability to conduct our analyses, process claims and appeals, conduct research and development activities, collect, process and prepare

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company financial information, provide information about our tests and other patient and physician education and outreach efforts through our website, and manage the administrative aspects of our business.

        Penalties for violations of these laws vary. For instance, penalties for failure to comply with a requirement of HIPAA and HITECH vary significantly, and include civil monetary penalties of up to $55,910 per violation, not to exceed approximately $1.68 million per calendar year for each provision of HIPAA that is violated and, in certain circumstances, criminal penalties with fines up to $250,000 per violation and/or imprisonment. However, a single breach incident can result in multiple violations, which can lead to significant financial penalties. In addition, numerous breach incidents could lead to possible penalties in excess of $1.68 million. A person who knowingly obtains or discloses individually identifiable health information in violation of HIPAA may face a criminal penalty of up to $50,000 and up to one-year imprisonment. The criminal penalties increase if the wrongful conduct involves false pretenses or the intent to sell, transfer or use identifiable health information for commercial advantage, personal gain or malicious harm.

        Further, various states, such as California and Massachusetts, have implemented similar privacy laws and regulations, such as the California Confidentiality of Medical Information Act, that impose restrictive requirements regulating the use and disclosure of health information and other personally identifiable information. These laws and regulations are not necessarily preempted by HIPAA, particularly if a state affords greater protection to individuals than HIPAA. Where state laws are more protective, we have to comply with the stricter provisions. In addition to fines and penalties imposed upon violators, some of these state laws also afford private rights of action to individuals who believe their personal information has been misused. California's patient privacy laws, for example, provide for penalties of up to $250,000 and permit injured parties to sue for damages. The interplay of federal and state laws may be subject to varying interpretations by courts and government agencies, creating complex compliance issues for us and data we receive, use and share, potentially exposing us to additional expense, adverse publicity and liability. Further, as regulatory focus on privacy issues continues to increase and laws and regulations concerning the protection of personal information expand and become more complex, these potential risks to our business could intensify.

        Compliance with U.S. and international data protection laws and regulations could cause us to incur substantial costs or require us to change our business practices and compliance procedures in a manner adverse to our business. Moreover, complying with these various laws could require us to take on more onerous obligations in our contracts, restrict our ability to collect, use and disclose data, or in some cases, impact our ability to operate in certain jurisdictions. We do not currently have formal policies and procedures in place, and have not conducted any internal or external audits, to ensure our compliance with all applicable data protection laws and regulations. Additionally, we do not currently have policies and procedures in place for assessing our third-party vendors' compliance with applicable data protection laws and regulations. Failure by us or by our third-party vendors to comply with U.S. and international data protection laws and regulations could result in government enforcement actions (which could include civil or criminal penalties), private litigation and/or adverse publicity and could negatively affect our operating results and business. Claims that we or our third-party vendors have violated individuals' privacy rights, failed to comply with data protection laws, or breached our contractual obligations, even if we or our third-party vendor, as applicable, are not found liable, could be expensive and time consuming to defend and could result in adverse publicity that could harm our business.

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Any clinical trial programs we conduct or research collaborations we enter into in the European Economic Area ("EEA") may subject us to European data protection laws including, the EU General Data Protection Regulation 2016/679 ("GDPR").

        We are subject to the GDPR, which applies extra-territorially and implements stringent operational requirements on controllers (e.g., sponsors) and processors (e.g., CROs, laboratories) of personal data, including, for example, high standards for obtaining valid consent from individuals to process their personal data (where consent is the legal ground relied upon), the requirements to provide detailed disclosures to individuals, restrictions on transfers of personal data from the EEA, short timelines for personal data breach notifications to data protection authorities, limitations on retention of personal data, additional considerations where processing health data and other "special categories of personal data" and specific obligations where third-party processors are engaged. Further, the GDPR provides that EU Member States may establish their own laws and regulations further restricting the processing of genetic data, biometric data, health data and other personal data, which could limit our ability to use and share such personal data or could cause our costs to increase. The GDPR imposes onerous accountability obligations requiring data controllers and processors to maintain a record of their data processing and policies. We do not currently have any formal data privacy policies and procedures in place and have not completed an assessment of whether we are in compliance with the GDPR. The GDPR also grants certain privacy rights to individuals (e.g., the right to access or erase their personal data). If our or our vendors' or service providers' privacy or data security measures fail to comply with the GDPR requirements, we may be subject to litigation, regulatory investigations, enforcement notices requiring us to change the way we use personal data and/or fines of up to 20 million Euros or up to 4% of the total worldwide annual turnover of the preceding financial year, whichever is higher, as well as compensation claims for financial or non-financial loss by affected individuals, negative publicity, reputational harm and a potential loss of business and goodwill. It is possible that these laws may be interpreted and applied in a manner that is inconsistent with our practices. If so, this could result in government-imposed fines or orders requiring that we change our practices, which could adversely affect our business.

Risks related to employee matters and managing growth

Our future success depends on our ability to retain our President and Chief Executive Officer, our Senior Vice President and Chief Scientific Officer, Chief Medical Officer, Vice President of Business Development and other key executives and to attract, retain and motivate qualified personnel.

        We are highly dependent on Christian S. Schade, our President and Chief Executive Officer, Scott M. Coiante, our Senior Vice President and Chief Financial Officer, Lars Abrahmsen, Ph.D., our Senior Vice President and Chief Scientific Officer, Eyal C. Attar, M.D., our Senior Vice President and Chief Medical Officer, and Gregory A. Korbel, Ph.D., our Vice President of Business Development, as well as the other principal members of scientific team. Our agreements with Mr. Schade, Mr. Coiante, Dr. Abrahmsen, Dr. Attar and Dr. Korbel do not prevent them from terminating their employment with us at any time. We do not maintain "key person" insurance for any of our executives or other employees. However, the loss of the services of any of these persons could impede the achievement of our research, development and commercialization objectives.

        Recruiting and retaining qualified scientific, clinical, manufacturing and sales and marketing personnel will also be critical to our success. We may not be able to attract and retain these personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy. Our consultants and advisors may be employed by employers other than us

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and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us.

Our employees may engage in misconduct or other improper activities, including non-compliance with regulatory standards and requirements, which could cause significant liability for us and harm our reputation.

        We are exposed to the risk of employee fraud or other misconduct, including intentional failures to comply with FDA regulations or similar regulations of comparable foreign regulatory authorities, provide accurate information to the FDA or comparable foreign regulatory authorities, comply with manufacturing standards we may establish, comply with federal and state healthcare fraud and abuse laws and regulations and similar laws and regulations established and enforced by comparable foreign regulatory authorities, report financial information or data accurately or disclose unauthorized activities to us. In particular, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, incentive programs and other business arrangements. Employee misconduct could also involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. It is not always possible to identify and deter employee misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws, standards or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and results of operations, including the imposition of significant fines or other sanctions.

We expect to expand our development and regulatory capabilities and potentially our sales and marketing capabilities, and as a result, we may encounter difficulties in managing our growth, which could disrupt our operations.

        We expect to experience significant growth in the number of our employees and the scope of our operations, particularly in the areas of drug development, clinical operations, regulatory affairs and, potentially, sales and marketing. To manage our anticipated future growth, we must continue to implement and improve our managerial, operational and financial systems, expand our facilities and continue to recruit and train additional qualified personnel. Due to our limited financial resources and the limited experience of our management team in managing a company with such anticipated growth, we may not be able to effectively manage the expansion of our operations or recruit and train additional qualified personnel. The physical expansion of our operations may lead to significant costs and may divert our management and business development resources. Any inability to manage growth could delay the execution of our business plans or disrupt our operations.

Risks related to tax matters

We have significant deferred tax assets, which may become devalued if we do not generate sufficient future taxable income, applicable corporate tax rates are reduced or if we experience an ownership change.

        Our total gross deferred tax assets as of December 31, 2018 were $12.8 million. Of that amount, $12.5 million relates to gross deferred tax assets in Aprea AB. Our anticipated activities are also expected to result in future significant net operating losses in the United States and Sweden resulting in additional deferred tax assets. Utilization of most deferred tax assets is dependent on generating sufficient future taxable income in the appropriate jurisdiction and/or entity. The company has provided a valuation allowance of $12.7 million on our net deferred tax assets as of December 31, 2018, based on all available evidence, it is considered more likely than not that all the recorded deferred tax assets

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will not be realized in a future period. Additionally, most of our deferred tax assets are determined by reference to applicable corporate income tax rates in Sweden or the United States. Accordingly, in the event of a reduction of any such corporate income tax rates, the carrying value of certain of our deferred tax assets would decrease.

        Moreover, our ability to use our net operating losses and other deferred tax assets to offset future taxable income in Sweden and the United States may be significantly limited if we experience an ownership change. For Swedish income tax purposes, an ownership change will generally occur when one, or several shareholders together, acquire shares representing more than 50 percent of the voting power over a five year period (under special provisions in Chapter 40 of the Swedish Income Tax Act; 1999:1229). Such an ownership change results in the forfeiture of tax losses carried forward exceeding 200 percent of the cost of the change of control. In this calculation, capital contributions to the company prior to the ownership change and in the preceding two years should reduce the cost of the change of control. Due to potential ownership changes under the Swedish Income Tax Act, we may be limited in our ability to realize a tax benefit on our deferred tax assets, whether or not we attain profitability in future years.

        For U.S. federal income tax purposes, an ownership change will generally occur when the percentage of our stock (by value) owned by one or more "5 percent shareholders" (as defined in the U.S. Internal Revenue Code of 1986, as amended) has increased by more than 50% over the lowest percentage owned by such shareholders at any time during the prior three years (calculated on a rolling basis). We anticipate that we will incur losses in the United States in the foreseeable future related to our research and development activities. Due to potential ownership changes under Section 382 of the Code, we may be limited in our ability to realize a tax benefit from the use of our deferred tax assets, whether or not we attain profitability in future years.

        In addition, our ability to utilize any future net operating losses may be limited by the recently enacted Pub. L. 115-97, commonly known as the Tax Cuts and Jobs Act of 2017 ("TCJA"). Under the TCJA, the amount of our net operating losses that we are permitted to deduct in any taxable year is limited to 80% of our taxable income in such year, where taxable income is determined without regard to the net operating loss deduction itself, while allowing unused net operating losses to be carried forward indefinitely.

        For these reasons, a material devaluation in our deferred tax assets due to insufficient taxable income, lower corporate income tax rates or ownership change would have an adverse effect on our results of operations and financial condition.

We may have taxable income as a result of the purging election we will make following the Holdco Reorganization

        While not entirely clear, we intend to treat Aprea AB as having been a passive foreign investment company, or PFIC, for U.S. federal income tax purposes prior to the Holdco Reorganization and treat Aprea Therapeutics, Inc. as having succeeded to the tax basis and holding periods of those shareholders in Aprea AB that exchanged their shares for our common stock. Based on such treatment, and absent a purging election as described below, the stock of Aprea AB held by Aprea Therapeutics, Inc. would have retained its status as stock of a PFIC with respect to all periods prior to the Holdco Reorganization (the "PFIC Taint") and therefore, absent a prior election by those shareholders to treat Aprea AB as a qualified electing fund, Aprea Therapeutics, Inc., would have been subject to certain adverse U.S. federal income tax consequences with respect to distributions received on such stock and gain recognized on the disposition of such stock. In order to purge the PFIC Taint on the stock of Aprea AB, and avoid such adverse tax consequences, following the Holdco Reorganization we intend to make a purging election in the form of a deemed dividend election under which, for U.S. federal income tax purposes, Aprea AB will be deemed to have made a distribution to

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Aprea Therapeutics, Inc. of all of its current and accumulated earnings and profits as determined for U.S. federal income tax purposes. Because we do not expect Aprea AB to have had any accumulated or current year earnings and profits, we do not expect the purging election to result in any incremental U.S. federal income taxes. We note, however, that earnings and profits are determined only at the end of the taxable year and no assurance can be given that Aprea AB will not have any earnings and profits.

We may be subject to current taxation on some of the income of our foreign subsidiaries even absent any cash distributions

        Because we hold directly or indirectly all of the shares of our foreign subsidiaries, including Aprea AB, such subsidiaries are treated as controlled foreign corporations ("CFC") for U.S. federal income tax purposes. For U.S. federal income tax purposes, Aprea Therapeutics, Inc. will therefore need to include in its taxable income each year Aprea AB's "subpart F income," and "global intangible low-taxed income", if any, even if no distributions are made.

Our foreign subsidiaries may directly become subject to U.S. federal income tax and be subject to a branch profits tax in the United States, which could reduce our after-tax returns and the value of our shares.

        We currently intend to conduct substantially all of our businesses and operations in a manner such that our foreign subsidiaries will not be treated as engaged in a trade or business in the United States and will not be subject to additional U.S. income tax or branch profits tax. However, it is not entirely clear when a foreign subsidiary is treated as being engaged in a trade or business in the United States for U.S. federal income tax purposes. Accordingly, we cannot assure you that the Internal Revenue Service ("IRS") will not contend, perhaps successfully, that our foreign subsidiaries were engaged in a trade or business in the United States or are subject to more U.S. income tax than they currently incur. A foreign corporation deemed to be so engaged would be subject to U.S. federal income tax, as well as branch profits tax, on its income that is treated as effectively connected with the conduct of that trade or business unless the corporation is entitled to relief under an applicable tax treaty, which is determined on an annual basis.

The ongoing effects of the 2017 Tax Cuts and Jobs Act and GILTI could make our results difficult to predict.

        Our effective tax rate may fluctuate in the future as a result of the TCJA, which included significant enacted changes in U.S. income tax law many aspects of which are not entirely clear and with respect to which guidance is mostly available only in proposed form. The enacted tax legislation included, among other new provisions, a reduction in the corporate tax rate, new limitations on the deductibility of net interest, the base erosion and anti-abuse minimum tax and new rules related to the global intangible low-taxed income of our foreign subsidiaries ("GILTI"). GILTI may require us to include in taxable income certain income of our foreign subsidiaries that are CFCs, though we may be eligible to claim foreign tax credits with respect to some of the taxes paid by such subsidiaries. While the U.S. tax authorities issued formal guidance as well as final and proposed regulations for GILTI, there are still certain aspects of the TCJA that remain unclear. We will continue to review the impact of GILTI and the other changes resulting from the TCJA as further guidance is issued. Any further guidance may result in changes to the interpretations and assumptions we made and actions we may take, which as a result may impact the amounts recorded with respect to international provisions of the TCJA, possibly materially.

Changes in U.S. federal income tax law and other jurisdictions could materially adversely affect an investment in our common shares.

        It is possible that tax laws in the United States and other jurisdictions will be changed. It remains difficult to predict whether or when there will be any tax law changes or further guidance by the

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authorities in the U.S. or elsewhere in the world that will have a material adverse effect on our business.

Risks related to our common stock and this offering

After this offering, our executive officers, directors and principal stockholders will exert significant control over matters submitted to stockholders for approval. This may prevent new investors from influencing significant corporate decisions.

        Upon the completion of this offering, our executive officers and directors and our stockholders which own more than 5% of our outstanding common stock before this offering will, in the aggregate, beneficially own shares representing approximately 67.7% of our common stock, not including any shares purchased by these stockholders in this offering. As a result, if these stockholders were to choose to act together, they would be able to exert significant control over matters submitted to our stockholders for approval, as well as our management and affairs. For example, these persons, if they choose to act together, would control the election of directors and approval of any merger, consolidation or sale of all or substantially all of our assets. This concentration of voting power could delay or prevent an acquisition of our company, or other significant corporate decisions, on terms that other stockholders may desire.

Provisions in our corporate charter documents and under Delaware law could make an acquisition of us, which may be beneficial to our stockholders, more difficult and may prevent attempts by our stockholders to replace or remove our current management.

        Provisions in our certificate of incorporation and our bylaws that will become effective upon the completion of this offering may discourage, delay or prevent a merger, acquisition or other change in control of us that stockholders may consider favorable, including transactions in which you might otherwise receive a premium for your shares. These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby depressing the market price of our common stock. In addition, because our board of directors is responsible for appointing the members of our management team, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for stockholders to replace members of our board of directors. Among other things, these provisions:

    establish a classified board of directors such that not all members of the board are elected at one time;

    allow the authorized number of our directors to be changed only by resolution of our board of directors;

    limit the manner in which stockholders can remove directors from the board;

    establish advance notice requirements for stockholder proposals that can be acted on at stockholder meetings and nominations to our board of directors;

    require that stockholder actions must be effected at a duly called stockholder meeting and prohibit actions by our stockholders by written consent;

    limit who may call stockholder meetings;

    authorize our board of directors to issue preferred stock without stockholder approval, which could be used to institute a "poison pill" that would work to dilute the stock ownership of a potential hostile acquirer, effectively preventing acquisitions that have not been approved by our board of directors; and

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    require the approval of the holders of at least 75% of the votes that all our stockholders would be entitled to cast to amend or repeal certain provisions of our charter or bylaws.

        Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law, which prohibits a person who owns in excess of 15% of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.

An active trading market for our common stock may not develop.

        Prior to this offering, there has been no public market for our common stock. The initial public offering price for our common stock will be determined through negotiations with the underwriters. Although our common stock has been approved for listing on The Nasdaq Global Select Market, an active trading market for our shares may never develop or be sustained following this offering. If an active market for our common stock does not develop or is not sustained, it may be difficult for you to sell shares you purchase in this offering without depressing the market price for the shares, or at all.

If you purchase shares of common stock in this offering, you will suffer immediate dilution of your investment.

        The initial public offering price of our common stock is substantially higher than the pro forma as adjusted net tangible book value per share of our common stock. Therefore, if you purchase shares of our common stock in this offering, you will pay a price per share that substantially exceeds our pro forma as adjusted net tangible book value per share after this offering. To the extent shares are issued under outstanding options, you will incur further dilution. Based on the initial public offering price of $15.00 per share, you will experience immediate dilution of $8.35 per share, representing the difference between our pro forma as adjusted net tangible book value per share after giving effect to this offering. In addition, purchasers of common stock in this offering will have contributed approximately 38% of the aggregate price paid by all purchasers of our stock but will own only approximately 29% of our common stock outstanding after this offering.

If securities analysts do not publish research or reports about our business or if they publish negative evaluations of our stock, the price of our stock could decline.

        The trading market for our common stock will rely in part on the research and reports that industry or financial analysts publish about us or our business. We do not currently have and may never obtain research coverage by industry or financial analysts. If no or few analysts commence coverage of us, the trading price of our stock would likely decrease. Even if we do obtain analyst coverage, if one or more of the analysts covering our business downgrade their evaluations of our stock, the price of our stock could decline. If one or more of these analysts cease to cover our stock, we could lose visibility in the market for our stock, which in turn could cause our stock price to decline.

The price of our common stock may be volatile and fluctuate substantially, which could result in substantial losses for purchasers of our common stock in this offering.

        Our stock price is likely to be volatile. The stock market in general and the market for pharmaceutical and biotechnology companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, you may not be able to sell your common stock at or above the initial public offering price. The market price for our common stock may be influenced by many factors, including:

    the timing and results of clinical trials of APR-246 and any of our other product candidates;

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    regulatory actions with respect to our product candidates or our competitors' products and product candidates;

    the success of existing or new competitive products or technologies;

    announcements by us or our competitors of significant acquisitions, strategic partnerships, joint ventures, collaborations or capital commitments;

    establishment or termination of collaborations for our product candidates or development programs;

    failure or discontinuation of any of our development programs;

    results of clinical trials of product candidates of our competitors;

    regulatory or legal developments in the United States and other countries;

    developments or disputes concerning patent applications, issued patents or other proprietary rights;

    the recruitment or departure of key personnel;

    the level of expenses related to any of our product candidates or development programs;

    the results of our efforts to discover, develop, acquire or in-license additional product candidates or products;

    actual or anticipated changes in estimates as to financial results or development timelines;

    announcement or expectation of additional financing efforts;

    sales of our common stock by us, our insiders or other stockholders;

    variations in our financial results or those of companies that are perceived to be similar to us;

    changes in estimates or recommendations by securities analysts, if any, that cover our stock;

    changes in the structure of healthcare payment systems;

    market conditions in the pharmaceutical and biotechnology sectors;

    general economic, industry and market conditions; and

    the other factors described in this "Risk Factors" section.

We could be subject to securities class action litigation.

        In the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us because pharmaceutical companies have experienced significant stock price volatility in recent years. If we face such litigation, it could result in substantial costs and a diversion of management's attention and our resources, which could harm our business.

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

        Our management will have broad discretion in the application of the net proceeds from this offering and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our common stock. The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of our product candidates.

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Pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

We are an "emerging growth company" and a "smaller reporting company," and the reduced disclosure requirements applicable to emerging growth companies or smaller reporting companies may make our common stock less attractive to investors.

        We are an "emerging growth company," as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. We may remain an emerging growth company for up to five years, or until such earlier time as we have more than $1.07 billion in annual revenue, the market value of our stock held by non-affiliates is more than $700 million or we issue more than $1 billion of non-convertible debt over a three-year period. For so long as we remain an emerging growth company, we are permitted and intend to rely on exemptions from certain disclosure requirements that are applicable to other public companies that are not emerging growth companies. These exemptions include not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act of 2002, or Section 404, not being required to comply with any requirement that may be adopted by the Public Company Accounting Oversight Board regarding mandatory audit firm rotation or a supplement to the auditor's report providing additional information about the audit and the financial statements, being permitted to present only two years of audited financial statements and a correspondingly reduced "Management's Discussion and Analysis of Financial Condition and Results of Operations" disclosure in this prospectus, reduced disclosure obligations regarding executive compensation and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. In this prospectus, we have taken advantage of reduced reporting obligations. In particular, in this prospectus, we have provided only two years of audited financial statements and have not included all of the executive compensation related information that would be required if we were not an emerging growth company. We cannot predict whether investors will find our common stock less attractive if we rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile.

        In addition, the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. An emerging growth company can therefore delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. However, we are choosing to "opt out" of such extended transition period, and, as a result, we will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for public companies that are not emerging growth companies. The JOBS Act provides that our decision to opt out of the extended transition period for complying with new or revised accounting standards is irrevocable.

        We are also a "smaller reporting company," as such term is defined in Rule 12b-2 of the Exchange Act, meaning that the market value of our common stock held by non-affiliates plus the proposed aggregate amount of gross proceeds to us as a result of this offering is less than $700 million and our annual revenue is less than $100 million during the most recently completed fiscal year. We may continue to be a smaller reporting company after this offering if either (i) the market value of our common stock held by non-affiliates is less than $250 million or (ii) our annual revenue is less than $100 million during the most recently completed fiscal year and the market value of our common stock held by non-affiliates is less than $700 million. If we are a smaller reporting company at the time we cease to be an emerging growth company, we may continue to rely on exemptions from certain disclosure requirements that are available to smaller reporting companies. Specifically, as a smaller reporting company we may choose to present only the two most recent fiscal years of audited financial statements in our Annual Report on Form 10-K and, similar to emerging growth companies, smaller reporting companies have reduced disclosure obligations regarding executive compensation.

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We will incur increased costs as a result of operating as a public company as we become subject to additional laws, regulations and listing exchange standards, and our management will be required to devote substantial time to new compliance initiatives.

        As a public company, and particularly after we are no longer an "emerging growth company" or a "smaller reporting company," we will incur significant legal, accounting and other expenses that we did not incur as a private company. In addition, the Sarbanes-Oxley Act of 2002 and rules subsequently implemented by the SEC and NASDAQ have imposed various requirements on public companies, including establishment and maintenance of effective disclosure and financial controls and corporate governance practices. Our management and other personnel will need to devote a substantial amount of time to these compliance initiatives. Moreover, these rules and regulations will increase our legal and financial compliance costs and will make some activities more time-consuming and costly. For example, we expect that these rules and regulations may make it more difficult and more expensive for us to obtain director and officer liability insurance.

        Pursuant to Section 404, we will be required to furnish a report by our management on our internal control over financial reporting, including an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. However, while we remain an emerging growth company, we will not be required to include an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. To achieve compliance with Section 404 within the prescribed period, we will be engaged in a process to document and evaluate our internal control over financial reporting, which is both costly and challenging. In this regard, we will need to continue to dedicate internal resources, potentially engage outside consultants and adopt a detailed work plan to assess and document the adequacy of internal control over financial reporting, continue steps to improve control processes as appropriate, validate through testing that controls are functioning as documented and implement a continuous reporting and improvement process for internal control over financial reporting. There is a risk that neither we nor our independent registered public accounting firm will be able to conclude within the prescribed timeframe that our internal control over financial reporting is effective as required by Section 404. This could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

        Accounting principles and related pronouncements, implementation guidelines and interpretations we apply to a wide range of matters that are relevant to our business, including, but not limited to, revenue recognition, leases and stock-based compensation, are complex and involve subjective assumptions, estimates and judgments by our management. Changes in accounting pronouncements or their interpretation or changes in underlying assumptions, estimates or judgments by our management could significantly change our reported or expected financial performance.

In connection with the preparation of our financial statements as of and for the years ended December 31, 2017 and 2018, the Company and our independent registered public accounting firm identified a material weakness in the Company's internal control over financial reporting. If we are not able to remediate the material weakness and otherwise to maintain an effective system of internal control over financial reporting in the future, investors may lose confidence in the accuracy and completeness of our financial reports, and the market price of our common stock could be materially and adversely affected.

        To date, we have not conducted an evaluation and testing of our internal control required by Section 404 of the Sarbanes-Oxley Act. We may experience situations in the future where our evaluation and testing processes required by Section 404 of the Sarbanes-Oxley Act, or work performed by independent registered accountants, may identify one or more material weaknesses in our internal controls over financial reporting that will result in our inability to assert that our internal control over financial reporting is effective. During our evaluation and testing, we may identify deficiencies and be unable to remediate them before we must provide the required reports.

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        In connection with the audits of our financial statements, we and our independent registered public accounting firm identified a material weakness related to our financial statement closing process, primarily related to the lack of sufficient skilled employees with U.S. GAAP and SEC reporting knowledge and experience for the purposes of timely and reliable financial reporting. Specifically, the material weakness identified relates to a lack of internal resources sufficient to prepare and review our consolidated financial statements and related disclosures in accordance with U.S. GAAP and financial reporting requirements set forth by the SEC.

        Under standards established by the Public Company Accounting Oversight Board, a material weakness is a deficiency, or combination of deficiencies, in internal control over financial reporting such that there is a reasonable possibility that a material misstatement of our annual or interim financial statements will not be prevented or detected and corrected on a timely basis.

        We are working to remediate the material weakness and are taking steps to strengthen our internal control over financial reporting such as, for example, the recent hiring of Scott M. Coiante as Chief Financial Officer. Additionally, we plan to further develop and implement formal policies, processes and documentation procedures relating to the financial reporting of the Company. The actions that we are taking are subject to ongoing executive management review, and will also be subject to audit committee oversight. If we are unable to successfully remediate the material weakness, or if in the future, we identify further material weaknesses in our internal controls over financial reporting, we may not detect errors on a timely basis and our financial statements may be materially misstated. We or our independent registered public accounting firm may not be able to conclude on an ongoing basis that we have effective internal control over financial reporting, which could harm our operating results, cause investors to lose confidence in our reported financial information and cause the trading price of our stock to fall. In addition, as a public company we will be required to file accurate and timely quarterly and annual reports with the SEC under the Exchange Act. Any failure to report our financial results on an accurate and timely basis could result in sanctions, lawsuits, delisting of our shares from The Nasdaq Global Select Market or other adverse consequences that would materially harm our business. In addition, we could become subject to investigations by NASDAQ, the SEC, and other regulatory authorities, and become subject to litigation from investors and stockholders, which could harm our reputation and our financial condition, or divert financial and management resources from our core business.

Because we do not anticipate paying any cash dividends on our common stock for the foreseeable future, capital appreciation, if any, of our common stock will be your sole source of gain.

        We have never declared or paid cash dividends on our common stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business. In addition, the terms of any future debt agreements may preclude us from paying dividends. As a result, capital appreciation, if any, of our common stock will be your sole source of gain for the foreseeable future.

Sales of a substantial number of shares of our common stock by our existing stockholders in the public market could cause our stock price to fall.

        Sales of a substantial number of shares of our common stock in the public market could occur at any time. These sales, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock. After this offering, we will have outstanding 19,876,532 shares of common stock based on the number of shares outstanding as of June 30, 2019 (including 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration Office on August 27, 2019).

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        Of these shares of our common stock, the 5,666,667 shares to be sold in this offering, plus any shares sold upon exercise of the underwriters' option to purchase additional shares, will be freely tradable, without restriction, in the public market immediately following this offering, unless purchased by our affiliates. All of the remaining shares are currently restricted as a result of securities laws or lock-up agreements but will be able to be sold after the offering as described in the "Shares Eligible for Future Sale" section of this prospectus. Moreover, after this offering, holders of approximately 14,200,000 shares of our common stock will have rights, subject to certain conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. We also intend to register all shares of common stock that we may issue under our equity compensation plans. Once we register these shares, they can be freely sold in the public market upon issuance, subject to volume limitations applicable to affiliates and the lock-up agreements described in the "Underwriting" section of this prospectus.

Our certificate of incorporation that will become effective upon the completion of this offering designates the state courts in the State of Delaware or, if no state court located within the State of Delaware has jurisdiction, the federal court for the District of Delaware, as the sole and exclusive forum for certain types of actions and proceedings that may be initiated by our stockholders, which could discourage lawsuits against the company and our directors, officers and employees.

        Our certificate of incorporation that will become effective upon the completion of this offering provides that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, the federal district court for the District of Delaware) will be the sole and exclusive forum for any derivative action or proceeding brought on our behalf under Delaware law, any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or employees to our company or our stockholders, any action asserting a claim against us arising pursuant to any provision of the Delaware General Corporation Law or our certificate of incorporation or bylaws, any action asserting a claim against us governed by the internal affairs doctrine, or any other action asserting an "internal corporate claim," as defined in Section 115 of the Delaware General Corporation Law. These exclusive-forum provisions do not apply to claims under the Securities Act of 1933, as amended, or the Securities Act, or the Exchange Act. This exclusive forum provision may limit the ability of our stockholders to bring a claim in a judicial forum that such stockholders find favorable for disputes with us or our directors, officers or employees, which may discourage such lawsuits against us and our directors, officers and employees. If a court were to find the exclusive-forum provision in our certificate of incorporation to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving the dispute in other jurisdictions, which could harm our results of operations.

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Special Note Regarding Forward-Looking Statements

        This prospectus contains forward-looking statements concerning our business, operations and financial performance and condition, as well as our plans, objectives and expectations for our business operations and financial performance and condition. Any statements contained herein that are not statements of historical facts may be deemed to be forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as "aim," "anticipate," "assume," "believe," "contemplate," "continue," "could," "due," "estimate," "expect," "goal," "intend," "may," "objective," "plan," "predict," "potential," "seek," "should," "target," "will," "would," and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:

    estimates of our expenses, capital requirements and our needs for additional financing;

    the prospects of APR-246 and other product candidates, which are still in development;

    outcome and results of ongoing or future preclinical studies and clinical trials of APR-246;

    the design of our multiple clinical trials, including the sample size, trial duration, endpoint definition, event rate assumptions and eligibility criteria;

    our expectations regarding the timing of data from our Phase 3 and additional clinical trials;

    market acceptance or commercial success of APR-246 and the degree of acceptance among physicians, patients, patient advocacy groups, health care payors and the medical community;

    our expectations regarding competition, potential market size, the size of the patient populations for APR-246, if approved for commercial use, and market acceptance;

    our ability to maintain regulatory approval of APR-246, and any related restrictions, limitations and/or warnings in the label of APR-246;

    the scope of protection we are able to establish and maintain for intellectual property rights covering APR-246;

    potential claims relating to our intellectual property and third-party intellectual property;

    the duration of our intellectual property estate that will provide protection for APR-246;

    developments relating to our competitors and our industry;

    our sales, marketing or distribution capabilities and our ability to commercialize APR-246, if we obtain regulatory approval;

    current and future agreements with third parties in connection with the manufacturing, commercialization, packaging and distribution of APR-246;

    our expectations regarding the ability of our current contract manufacturing partners to produce APR-246 in the quantities and timeframe that we will require;

    our expectations regarding our future costs of goods;

    our ability to attract, retain and motivate key personnel and increase the size of our organization;

    our ability to establish collaborations in lieu of obtaining additional financing;

    the impact of government laws and regulations;

    our anticipated use of proceeds from this offering;

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    our financial performance; and

    our expectations regarding the time during which we will be an emerging growth company under the JOBS Act or a smaller reporting company under the Exchange Act.

        These forward-looking statements are based on management's current expectations, estimates, forecasts, and projections about our business and the industry in which we operate and management's beliefs and assumptions and are not guarantees of future performance or development and involve known and unknown risks, uncertainties, and other factors that are in some cases beyond our control. As a result, any or all of our forward-looking statements in this prospectus may turn out to be inaccurate. Factors that may cause actual results to differ materially from current expectations include, among other things, those listed under "Risk Factors" and elsewhere in this prospectus. Potential investors are urged to consider these factors carefully in evaluating the forward-looking statements. These forward-looking statements speak only as of the date of this prospectus. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future. You should read this prospectus with the understanding that our actual future results, levels of activity, performance and events and circumstances may be materially different from what we expect.

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Use of Proceeds

        We estimate that the net proceeds from our issuance and sale of 5,666,667 shares of our common stock in this offering will be approximately $75.9 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us. If the underwriters exercise their option to purchase additional shares in full, we estimate that our net proceeds will be approximately $87.7 million.

        We intend to use the net proceeds from the offering as follows:

    Approximately $20.0 million to $30.0 million to fund future Phase 1b/2 clinical studies of APR-246 for solid tumor and hematological malignancies as well as additional future clinical studies to be determined if the data derived from such Phase 1b/2 clinical studies is favorable;

    Approximately $10.0 million to $15.0 million to fund continued research and development activities for APR-548, including ongoing IND-enabling studies and a first-in-human clinical trial;

    Approximately $5.0 million to $10.0 million to fund the ongoing preclinical and clinical development of APR-246, including preparation and submission of a New Drug Application (NDA) in MDS; and

    The remainder to fund general research and development activities, working capital and other general corporate activities including the buildout of infrastructure to support the advancement of our product candidates.

        Our expected use of proceeds from this offering represents our current intentions based on our present plans and business condition. As of the date of this prospectus, we cannot predict with certainty all of the particular uses for the proceeds to be received upon the completion of this offering or the actual amounts that we will spend on the uses set forth above. We may also use a portion of the proceeds to in-license, acquire or invest in additional businesses, technologies, products or assets. Although we have no specific agreements, commitments or understandings with respect to any in-licensing activity or acquisition, we evaluate these opportunities and engage in related discussions with other companies from time to time.

        The net proceeds from this offering, together with our cash and cash equivalents, may not be sufficient for us to conduct through completion any additional existing clinical trials of APR-246 or to otherwise complete the development of APR-246.

        The amount and timing of our actual expenditures will depend on numerous factors, including the results of our research and development efforts, the timing and outcome of any ongoing or future clinical trials, and the timing and outcome of regulatory submissions. As a result, our management will have broad discretion over the use of the proceeds from this offering.

        Pending the use of the proceeds from this offering, we may invest the proceeds in interest-bearing, investment-grade securities, certificates of deposit and/or U.S. government securities.

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Dividend Policy

        We have never declared or paid any dividends on our common stock. We do not anticipate declaring or paying any cash dividends on our common stock in the foreseeable future. Any future determination to declare and pay cash dividends, if any, will be made at the discretion of our board of directors and will depend on a variety of factors, including applicable laws, our financial condition, results of operations, contractual restrictions, capital requirements, business prospects, general business or financial market conditions and other factors our board of directors may deem relevant.

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Corporate Reorganization

Aprea AB

        Prior to the Holdco Reorganization, the capital structure of Aprea AB consisted of four classes of equity interests: ordinary shares; Series A preferred shares; Series B preferred shares; and Series C preferred shares.

Corporate reorganization

        On September 20, 2019, we engaged in a series of transactions, which we refer to collectively as the Holdco Reorganization. As a result of the Holdco Reorganization, Aprea AB became a wholly-owned subsidiary of Aprea Therapeutics, Inc. and our consolidated financial statements will be reported from Aprea Therapeutics, Inc. We, Aprea AB, and the holders of all of the issued and outstanding equity interests of Aprea AB entered into a Share Contribution and Exchange Agreement, dated as of June 13, 2019, pursuant to which the Holdco Reorganization was effected.

        In May 2019, we formed Aprea Therapeutics, Inc. as a stand-alone entity. The remaining steps to the Holdco Reorganization that were effected on September 20, 2019 included:

    Each holder of Aprea AB equity interests contributed, transferred, granted, assigned and delivered to us all of its right, title and interest in and to all Aprea AB equity interests owned by such holder;

    In exchange for each Aprea AB ordinary share contributed by a holder, we issued to such holder one share of our common stock;

    In exchange for each Aprea AB Series A preferred share contributed by a holder, we issued to such holder one share of our Series A preferred stock;

    In exchange for each Aprea AB Series B preferred share contributed by a holder, we issued to such holder one share of our Series B preferred stock;

    In exchange for each Aprea AB Series C preferred share contributed by a holder, we issued to such holder one share of our Series C preferred stock; and

    Each outstanding option to purchase Aprea AB ordinary shares issued by Aprea AB pursuant to the 2016 Stock Incentive Plan was cancelled, and we issued to the holder of such Aprea AB option, a substitute option to purchase, on the same terms and conditions as were applicable to such Aprea AB option, shares of our common stock pursuant to our 2019 Stock Incentive Plan; except that with respect to vested options held by U.S. employees, we assumed such options and exercised them for newly issued shares of Aprea.

        Immediately prior to the completion of this offering, with the consent of shareholders representing a majority of our outstanding preferred shares, all outstanding shares of our convertible preferred stock, including the shares of our Series A preferred stock, Series B preferred stock and Series C preferred stock issued as part of the Holdco Reorganization will be converted into shares of our common stock on a 1-for-1.6045 basis. As a result of the Holdco Reorganization and such subsequent conversion, the former holders of all of the issued and outstanding equity interests of Aprea AB will have received 100% of our outstanding common stock as of immediately prior to the completion of the offering.

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Capitalization

        The following table sets forth our cash and cash equivalents and our capitalization as of June 30, 2019:

    on an actual basis with respect to Aprea AB (including 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration Office on August 27, 2019);

    on a pro forma basis to give effect to (i) the Holdco Reorganization described under the section titled "Corporate Reorganization"; (ii) the 1 for 1.6045 split of our common stock which took place on September 26, 2019; (iii) the conversion of all of our outstanding shares of convertible preferred stock into an aggregate of 13,028,292 shares of common stock immediately prior to the completion of this offering and (iv) the filing and effectiveness of our amended and restated certificate of incorporation; and

    on a pro forma as adjusted basis to give further effect to our issuance and sale of 5,666,667 shares of our common stock in this offering at the initial public offering price of $15.00 per share, after deducting underwriting discounts and commissions and estimated offering expenses payable by us.

        Our capitalization following the completion of this offering will depend on the actual initial public offering price and other terms of this offering determined at pricing. You should read this table together with our financial statements and the related notes appearing at the end of this prospectus

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and the sections of this prospectus titled "Corporate Reorganization," "Selected Financial Data" and "Management's Discussion and Analysis of Financial Condition and Results of Operations."

 
  June 30, 2019  
 
  Actual   Pro forma   Pro forma
as adjusted
 

Cash and cash equivalents

  $ 60,994,738   $ 60,994,738   $ 136,844,743  

Convertible preferred stock:

                   

Series A convertible preferred stock, $0.11 par value; 612,446 shares issued and outstanding actual; no shares outstanding, pro forma and pro forma as adjusted

    6,483,044          

Series B convertible preferred stock, $0.11 par value; 7,235,969 shares issued and outstanding actual; no shares outstanding, pro forma and pro forma as adjusted

    49,742,942          

Series C convertible preferred stock, $0.11 par value; 5,179,877 shares issued and outstanding actual; no shares outstanding, pro forma and pro forma as adjusted

    61,963,007          

Total convertible preferred stock

    118,188,993          

Stockholders' Deficit

                   

Common stock, $0.11 par value actual, $0.001 par value pro forma and pro forma as adjusted; 1,181,573 shares issued and outstanding actual; 14,209,865 shares issued and outstanding, pro forma 19,876,532 shares issued and outstanding, and pro forma as adjusted

    129,974     14,210     19,877  

Additional paid-in capital

    19,971,732     138,276,489     214,120,827  

Accumulated other comprehensive loss

    (10,747,992 )   (10,747,992 )   (10,747,992 )

Accumulated deficit

    (71,206,106 )   (71,206,106 )   (71,206,106 )

Total stockholders' equity (deficit)

    (61,852,392 )   56,336,601     132,186,606  

Total Capitalization

  $ 56,336,601   $ 56,336,601   $ 132,186,606  

        The table above does not include:

    2,761,794 shares of our common stock issuable upon the exercise of stock options outstanding as of June 30, 2019, at a weighted average exercise price of $1.66 per share; and

    2,488,206 shares of common stock reserved for issuance pursuant to future awards under our 2019 Stock Incentive Plan or our Employee Stock Purchase Plan, plus any future increases in the number of shares of common stock reserved for issuance under our 2019 Stock Incentive Plan or our Employee Stock Purchase Plan pursuant to provisions thereof that automatically increase the share reserve under the plan each year.

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Dilution

        If you invest in our common stock in this offering, your ownership interest will be diluted immediately to the extent of the difference between the initial public offering price per share of our common stock and the pro forma as adjusted net tangible book value per share of our common stock immediately after this offering.

        Our historical net tangible book value (deficit) as of June 30, 2019 was $(61.9) million, or $(52.35) per share of our common stock. Our historical net tangible book value (deficit) is the amount of our total assets less our total liabilities and convertible preferred stock, which is not included in our stockholders' deficit. Historical net tangible book value (deficit) per share represents historical net tangible book value (deficit) divided by the number of shares of our common stock outstanding as of June 30, 2019 (including 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration Office on August 27, 2019) after giving effect to the 1 for 1.6045 split of our common stock which took place on September 26, 2019.

        Our pro forma net tangible book value as of June 30, 2019 was $56.3 million, or $3.96 per share of our common stock. Pro forma net tangible book value represents the amount of our total assets less our total liabilities, after giving effect to (i) the Holdco Reorganization described under the section titled "Corporate Reorganization," pursuant to which all of the issued and outstanding stock of Aprea Therapeutics AB was exchanged for common stock, preferred stock or options, as applicable, of Aprea Therapeutics, Inc., (ii) the 1 for 1.6045 split of our common stock which took place on September 26, 2019 and (iii) the conversion of all of our outstanding shares of convertible preferred stock into an aggregate of 13,028,292 shares of our common stock immediately prior to the completion of this offering. Pro forma net tangible book value per share represents pro forma net tangible book value divided by the total number of shares of common stock outstanding as of June 30, 2019 (including 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration Office on August 27, 2019), after giving effect to the Holdco Reorganization, the 1 for 1.6045 split of our common stock which took place on September 26, 2019 and the automatic conversion of all outstanding shares of our preferred stock into common stock immediately prior to the completion of this offering.

        After giving further effect to our sale of 5,666,667 shares of common stock in this offering at the initial public offering price of $15.00 per share, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us, our pro forma as adjusted net tangible book value as of June 30, 2019 would have been $132.2 million, or $6.65 per share. This represents an immediate increase in pro forma as adjusted net tangible book value of $2.69 per share to our existing stockholders and an immediate dilution in pro forma as adjusted net tangible book value of $8.35 per share to new investors purchasing common stock in this offering. Dilution per share to new investors purchasing common stock in this offering is determined by subtracting pro forma as adjusted net

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tangible book value per share after this offering from the initial public offering price per share paid by new investors. The following table illustrates this dilution on a per share basis:

Initial public offering price per share

        $ 15.00  

Historical net tangible book value (deficit) per share as of June 30, 2019

  $ (52.35 )      

Pro forma increase in net tangible book value per share attributable to the conversion of our Convertible Preferred Stock immediately prior to the completion of this offering

  $ 56.31        

Pro forma net tangible book value per share as of June 30, 2019

  $ 3.96        

Increase in pro forma net tangible book value per share attributable to new investors participating in this offering

  $ 2.69        

Pro forma as adjusted net tangible book value per share after this offering

          6.65  

Dilution in pro forma net tangible book value per share to new investors participating in this offering

        $ 8.35  

        If the underwriters exercise their option to purchase additional shares in full, our pro forma as adjusted net tangible book value per share after this offering would be $6.95 per share, representing an immediate increase in pro forma as adjusted net tangible book value per share of $2.99 to existing stockholders and an immediate dilution in pro forma as adjusted net tangible book value per share of $8.05 to new investors purchasing common stock in this offering, at an initial public offering price of $15.00 per share, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us. If any shares are issued upon exercise of outstanding options, you will experience further dilution.

        The following table summarizes, on a pro forma as adjusted basis, as of June 30, 2019, the differences between the number of shares of common stock purchased from us, the total consideration paid to us and the average price per share paid by existing stockholders and by new investors purchasing shares of common stock in this offering. The calculation below is based on an initial public offering price of $15.00 per share, before deducting underwriting discounts and commissions and estimated offering expenses payable by us:

 
  Shares purchased   Total consideration    
 
 
  Average price
per share
 
 
  Number   Percent   Amount   Percent  

Existing stockholders before this offering

    14,209,865     71 % $ 136,926,976     62 % $ 9.64  

Investors participating in this offering

    5,666,667     29 %   85,000,005     38 % $ 15.00  

Total

    19,876,532     100.0 % $ 221,926,981     100.0 %      

        The table above assumes no exercise of the underwriters' option to purchase additional shares in this offering. If the underwriters' option to purchase additional shares is exercised in full, the number of shares of our common stock held by existing stockholders would be reduced to 69% of the total number of shares of our common stock outstanding after this offering, and the number of shares of common stock held by new investors participating in the offering would be increased to 31% of the total number of shares of our common stock outstanding after this offering.

        The number of shares purchased from us by existing stockholders is based on 14,209,865 shares of our common stock outstanding as of June 30, 2019 (including 2,807 shares of common stock from the exercise of stock options on March 25, 2019, which were registered pursuant to Swedish law with the Swedish Companies Registration Office on August 27, 2019), after giving effect to (i) the Holdco Reorganization described under the section titled "Corporate Reorganization," pursuant to which all of the issued and outstanding stock of Aprea Therapeutics AB was exchanged for common stock, preferred stock or options, as applicable, of Aprea Therapeutics, Inc., (ii) the 1 for 1.6045 split of our common stock which took place on September 26, 2019 and (iii) the conversion of all outstanding

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shares of our convertible preferred stock, including the shares issued as part of the Holdco Reorganization, into an aggregate of 13,028,292 shares of our common stock, immediately prior to the completion of this offering, and excludes:

    2,761,794 shares of our common stock issuable upon the exercise of stock options outstanding as of June 30, 2019, at a weighted average exercise price of $1.66 per share; and

    2,488,206 shares of common stock reserved for issuance pursuant to future awards under our 2019 Stock Incentive Plan or our Employee Stock Purchase Plan, plus any future increases in the number of shares of common stock reserved for issuance under our 2019 Stock Incentive Plan or our Employee Stock Purchase Plan pursuant to provisions thereof that automatically increase the share reserve under the plan each year.

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Selected Financial Data

        You should read the following selected financial data together with our financial statements and the related notes appearing at the end of this prospectus and the "Management's Discussion and Analysis of Financial Condition and Results of Operations" section of this prospectus. We have derived the statement of operations data for the years ended December 31, 2017 and 2018 and the balance sheet data as of December 31, 2017 and 2018 from our audited financial statements appearing at the end of this prospectus. The consolidated statements of operations data for the six months ended June 30, 2018 and 2019 and the consolidated balance sheet data at June 30, 2019 are derived from our unaudited condensed consolidated financial statements included in this prospectus. The unaudited condensed consolidated financial statements include, in the opinion of management, all adjustments that management considers necessary for the fair presentation of the consolidated financial information set forth in those statements. Our historical results are not necessarily indicative of results that should be expected in any future period.

 
  Years ended December 31,   Six months ended June 30,  
 
  2017   2018   2018   2019  
 
   
   
  (unaudited)
 

Consolidated Statement of Operations Data:

                         

Operating expenses:

                         

Research and development

  $ 13,392,631   $ 14,194,732   $ 7,492,788   $ 7,998,270  

General and administrative

    2,459,744     2,294,671     1,166,520   $ 2,347,915  

Total operating expenses

    15,852,375     16,489,403     8,659,308     10,346,185  

Other income (expense):

                         

Interest expense

    (15 )   (182 )   (188 )   (7,439 )

Foreign currency gain

    662,140     961,316     949,158     1,615,974  

Total other income (expense)

    662,125     961,134     948,970     1,608,535  

Net loss

  $ (15,190,250 ) $ (15,528,269 ) $ (7,710,338 ) $ (8,737,650 )

Net loss per share attributable to common stockholders, basic and diluted(1)

  $ (13.17 ) $ (13.45 ) $ (6.68 ) $ (7.43 )

Weighted average common shares outstanding, basic and diluted(1)

    1,153,069     1,154,368     1,154,107     1,176,417  

Pro forma net loss per share attributable to common stockholders, basic and diluted (unaudited)(1)

        $ (1.65 )       $ (0.62 )

Pro forma weighted average common shares outstanding, basic and diluted (unaudited)(1)

          9,428,873           14,075,669  

(1)
See Note 2 to our audited and unaudited interim financial statements included elsewhere in this prospectus for an explanation of the method used to calculate basic and diluted net loss per share and unaudited pro forma basic and diluted net loss per share as well as the weighted-average number of common shares used in the computation of the per share amounts.
 
  December 31,   June 30,  
 
  2017   2018   2019  

Consolidated Balance Sheet Data:

                   

Cash and cash equivalents

  $ 24,401,488   $ 65,675,931   $ 60,994,738  

Working capital(1)

    20,430,334     61,129,968     56,215,210  

Total assets

    24,761,804     66,022,638     62,214,654  

Total liabilities

    4,301,013     4,868,109     5,878,053  

Convertible preferred stock

    56,225,986     112,590,631     118,188,993  

Total stockholders' deficit

    (35,765,195 )   (51,436,102 )   (61,852,392 )

(1)
We define working capital as current assets less current liabilities.

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Management's Discussion and Analysis of Financial Condition and Results of Operations

        You should read the following discussion and analysis of our financial condition and results of operations together with the "Selected Financial Data" section of this prospectus and our financial statements and the related notes included at the end of this prospectus. This discussion and other parts of this prospectus contain forward-looking statements that involve risks and uncertainties, such as statements of our plans, objectives, expectations and intentions. As a result of many factors, including those factors set forth in the "Risk Factors" section of this prospectus, our actual results could differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

Overview

        We are a clinical-stage biopharmaceutical company focused on developing and commercializing novel cancer therapeutics that reactivate mutant p53 tumor suppressor protein. p53 is the protein expressed from the TP53 gene, the most commonly mutated gene in cancer. We believe that mutant p53 is an attractive therapeutic target due to the high incidence of p53 mutations across a range of cancer types and its involvement in key cellular activities such as apoptosis. Cancer patients with mutant p53 face a significantly inferior prognosis even when treated with the current standard of care, and a large unmet need for these patients remains. Our lead product candidate, APR-246, is a small molecule p53 reactivator that is in late-stage clinical development for hematologic malignancies, including myelodysplastic syndromes, or MDS, and acute myeloid leukemia, or AML. APR-246 has received Orphan Drug and Fast Track designations from the FDA for MDS, and Orphan Drug designation from the EMA for MDS, AML and ovarian cancer, and we believe APR-246 will be a first-in-class therapy if approved by applicable regulators. We have commenced a pivotal Phase 3 trial of APR-246 with azacitidine for frontline treatment of TP53 mutant MDS and expect initial data from this trial in the second half of 2020. Our pivotal Phase 3 trial is supported by data from two ongoing Phase 1b/2 investigator initiated trials, one in the U.S. and one in France, testing APR-246 with azacitidine as frontline treatment in TP53 mutant MDS and AML patients.

        In the ongoing U.S. Phase 1b/2 trial, sponsored by Dr. David Sallman of the H. Lee Moffitt Cancer Center and Research Institute, or Moffitt, we have observed an objective response rate, or ORR, of 88% and a complete remission, or CR, rate of 59% in 41 response-evaluable MDS/AML patients treated with APR-246 and azacitidine, as of July 2019 and we expect a final CR endpoint in the second half of 2019. In MDS patients, the CR rate was 61%, with an additional 27% achieving non-CR responses. In AML patients, the CR rate was 50%, with an additional 38% achieving non-CR responses. In addition, 46% of evaluable patients were able to discontinue treatment in order to proceed to allogeneic hematopoietic stem cell transplantation, or allo-HCT. Allo-HCT is currently the only recognized therapy believed to increase the likelihood of long term survival for TP53 mutant MDS and AML patients in remission. In the ongoing French Phase 1b/2 trial, sponsored by Groupe Francophone des Myelodysplasies, or GFM, under lead investigator Prof. Pierre Fenaux, we have observed an ORR of 75% and a CR rate of 56% in 16 response-evaluable patients treated with APR-246 and azacitidine, as of July 2019 and we expect a final CR endpoint in the first half of 2020. In MDS patients, the CR rate was 55%, with an additional 18% achieving non-CR responses. In AML patients, the CR rate was 60%, with an additional 20% achieving non-CR responses. We expect the results of our pivotal Phase 3 trial and the U.S. and French Phase 1b/2 trials will be submitted in support of marketing applications to the FDA and EMA. We are also developing a next-generation small molecule p53 reactivator, APR-548, for potential use in multiple hematologic malignancies and other oncologic indications, and expect to file an IND with the FDA in the first half of 2020. We have assembled a management team with extensive experience in the discovery and development of novel oncology drugs. Our management team is supported by our world-class scientific advisors and leading

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life science investors in their mission to successfully develop p53-reactivating therapies for cancer patients.

        Aprea Therapeutics AB, or Aprea AB, was originally incorporated in 2002 and commenced principal operations in 2006. In connection with this initial public offering, we incorporated Aprea Therapeutics, Inc. in May 2019. We completed the Holdco Reorganization on September 20, 2019, as a result of which all of the issued and outstanding stock of Aprea AB was exchanged for common stock, preferred stock or options, as applicable, of Aprea Therapeutics, Inc. As a result of such transactions, Aprea AB became a wholly-owned subsidiary of Aprea Therapeutics, Inc. For more information, please see the section titled "Corporate Reorganization".

        We have devoted substantially all of our resources to developing our product candidates, including APR-246, building our intellectual property portfolio, business planning, raising capital and providing general and administrative support for these operations. To date, we have financed our operations through private placements of preferred stock. Through June 30, 2019, we had received net proceeds of $136.9 million from our sales of preferred and common stock.

        Since our inception, we have incurred significant losses on an aggregate basis. Our ability to generate product revenue sufficient to achieve profitability will depend on the successful development and eventual commercialization of one or more of our product candidates. Our net losses were $8.7 million for the six months ended June 30, 2019 and $15.2 million and $15.5 million for the years ended December 31, 2017 and 2018, respectively. As of June 30, 2019, we had an accumulated deficit of $71.2 million. These losses have resulted primarily from costs incurred in connection with research and development activities, patent investment, and general and administrative costs associated with our operations. We expect to continue to incur significant expenses and increasing operating losses for at least the next several years.

        We anticipate that our expenses will increase substantially if and as we:

    conduct our current and future clinical trials and additional preclinical research of APR-246;

    initiate and continue research and preclinical and clinical development of our other product candidates;

    seek to identify and develop additional product candidates;

    seek marketing approvals for any of our product candidates that successfully complete clinical trials, if any;

    establish a sales, marketing, manufacturing and distribution infrastructure to commercialize any products for which we may obtain marketing approval;

    require the manufacture of larger quantities of our product candidates for clinical development and potentially commercialization;

    maintain, expand, protect and enforce our intellectual property portfolio;

    acquire or in-license other drugs and technologies;

    defend against any claims of infringement, misappropriation or other violation of third-party intellectual property;

    hire and retain additional clinical, quality control and scientific personnel;

    add operational, financial and management information systems and personnel, including personnel to support our drug development, any future commercialization efforts and our transition to a public company; and

    operate as a public company.

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        Upon the completion of this offering, we expect to incur additional costs associated with operating as a public company. Furthermore, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to product manufacturing, marketing, sales and distribution.

        As a result, we will need additional financing to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity or debt financings or other sources, which may include collaborations with third parties. We may be unable to raise additional funds or enter into other agreements or arrangements when needed on favorable terms, or at all. If we fail to raise capital or enter into such agreements as and when needed, we may have to significantly delay, scale back or discontinue the development or commercialization of one or more of our product candidates.

        Because of the numerous risks and uncertainties associated with product development, we are unable to predict the timing or amount of increased expenses or when or if we will be able to achieve or maintain profitability. Even if we are able to generate revenue from product sales, we may not become profitable. If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to continue our operations at planned levels and be forced to reduce or terminate our operations.

        As of June 30, 2019, we had cash and cash equivalents of $61.0 million. We believe that the anticipated net proceeds from this offering, together with our existing cash and cash equivalents, will enable us to fund our operating expenses and capital expenditure requirements into 2023. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. See "—Liquidity and Capital Resources."

Components of our results of operations

Revenue

        We have not generated any revenue from product sales and do not expect to generate any revenue from the sale of products in the near future. If our development efforts for APR-246 or other product candidates that we may develop in the future are successful and result in marketing approval or collaboration or license agreements with third parties, we may generate revenue in the future from a combination of product sales or payments from collaboration or license agreements that we may enter into with third parties.

Operating expenses

        Our expenses since inception have consisted solely of research and development costs and general and administrative costs.

Research and development expenses

        Research and development expenses consist primarily of costs incurred for our research activities, including our discovery efforts, and the development of our product candidates, and include:

    expenses incurred under agreements with third parties, including contract research organizations, or CROs, that conduct research, preclinical activities and clinical trials on our behalf as well as contract manufacturing organizations, or CMOs, that manufacture our product candidates for use in our preclinical and clinical trials;

    salaries, benefits and other related costs, including stock-based compensation expense, for personnel engaged in research and development functions;

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    costs of outside consultants, including their fees, stock-based compensation and related travel expenses;

    costs of laboratory supplies and acquiring, developing and manufacturing preclinical study and clinical trial materials;

    expenses related to compliance with regulatory requirements; and

    facility-related expenses, which include direct depreciation costs and allocated expenses for rent and maintenance of facilities and other operating costs.

        We expense research and development costs as incurred. We recognize costs for certain development activities, such as clinical trials, based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to us by our vendors and our clinical investigative sites. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected in our financial statements as prepaid or accrued research and development expenses.

        We typically use our employee and infrastructure resources across our development programs. We track outsourced development costs and milestone payments made to our research partners by product candidate or development program, but we do not allocate personnel costs or other internal costs to specific development programs or product candidates.

        Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. We expect that our research and development expenses will continue to increase for the foreseeable future as we initiate additional clinical trials of APR-246, pursue later stages of clinical development of APR-246, initiate clinical trials for product candidates other than APR-246 and continue to discover and develop additional product candidates.

        We cannot determine with certainty the duration and costs of the current or future clinical trials of our product candidates or if, when, or to what extent we will generate revenue from the commercialization and sale of any our product candidates for which we obtain marketing approval. We may never succeed in obtaining marketing approval for any of our product candidates. The duration, costs and timing of clinical trials and development of our product candidates will depend on a variety of factors, including:

    the scope, rate of progress, expense and results of our ongoing clinical trials of APR-246, as well as of any future clinical trials of APR-246 or other product candidates and other research and development activities that we may conduct;

    uncertainties in clinical trial design and patient enrollment rates;

    significant and changing government regulation and regulatory guidance;

    the timing and receipt of any marketing approvals; and

    the expense of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights.

        A change in the outcome of any of these variables with respect to the development of a product candidate could mean a significant change in the costs and timing associated with the development of that product candidate. For example, if the U.S. Food and Drug Administration, or FDA, or another regulatory authority were to require us to conduct clinical trials beyond those that we anticipate will be required for the completion of clinical development of a product candidate, or if we experience

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significant trial delays due to patient enrollment or other reasons, we would be required to expend significant additional financial resources and time on the completion of clinical development.

        We are currently conducting multiple clinical trials of APR-246: our Phase 3 trial in the United States for the treatment of TP53 mutant MDS with azacitidine, our Phase 1b/2 trials in the United States and France for the treatment of MDS and AML with azacitidine, and our Phase 2 trial of post-transplant maintenance therapy with azacitidine in MDS and AML. At this time, we cannot reasonably estimate the cost for initiating and completing other clinical trials of APR-246 and preclinical studies of APR-246, as it will be highly dependent on the clinical data from ongoing clinical trials as well as any target disease subpopulations chosen for further evaluation.

General and administrative expenses

        General and administrative expenses consist primarily of salaries and other related costs, including stock-based compensation, for personnel in our executive, finance, corporate and business development and administrative functions. General and administrative expenses also include legal fees relating to patent and corporate matters; professional fees for accounting, auditing, tax and consulting services; insurance costs; travel expenses; and facility-related expenses, which include direct depreciation costs and allocated expenses for rent and maintenance of facilities and other operating costs.

        We expect that our general and administrative expenses will increase in the future as we increase our general and administrative personnel headcount to support personnel in research and development and to support our operations generally as we increase our research and development activities and activities related to the potential commercialization of our product candidates. We also expect to incur increased expenses associated with being a public company, including costs of accounting, audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing and SEC requirements; director and officer insurance costs; and investor and public relations costs.

Other income and expense

Interest income and expense

        Interest expense consists of bank charges and fees incurred on our cash and cash equivalents. We anticipate that our interest income will increase in the future as we expect our investment balances to be higher due to anticipated cash proceeds from this offering.

Foreign currency gain

        Our consolidated financial statements are presented in U.S. dollars, which is our reporting currency. The financial position and results of operations of our subsidiaries Aprea AB and Aprea Personal AB are measured using the foreign subsidiaries' local currency as the functional currency. Aprea AB cash accounts holding U.S. dollars are remeasured based upon the exchange rate at the date of remeasurement with the resulting gain or loss included in the consolidated statement of operations and comprehensive loss. Expenses of such subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the consolidated balance sheet date. The resulting translation gain and loss adjustments are recorded directly as a separate component of shareholders' equity and as other comprehensive loss on the consolidated statement of operations and comprehensive loss.

Income taxes

        Since Aprea AB's inception in 2002, we have not recorded any U.S. federal, state or foreign income tax expense or benefits for the net losses we have incurred in any year, due to our uncertainty of realizing a benefit from those items. We have provided a valuation allowance for the full amount of

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the net deferred tax assets as, based on all available evidence, it is considered more likely than not that all the recorded deferred tax assets will not be realized in a future period. At December 31, 2018, we had $61.6 million, $0.5 million and $0.4 million of foreign, federal and state net operating loss carryforwards, respectively, that expire at various dates through 2036. Certain of these foreign, federal and state net operating loss carryforwards may be subject to Internal Revenue Code Section 382 or similar provisions, which impose limitations on their utilization amounts.

Critical accounting policies and use of estimates

        Our management's discussion and analysis of financial condition and results of operations is based on our financial statements, which have been prepared in accordance with generally accepted accounting principles in the United States. The preparation of our financial statements and related disclosures requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, costs and expenses and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions or conditions.

        While our significant accounting policies are described in more detail in the notes to our financial statements appearing at the end of this prospectus, we believe that the following accounting policies are those most critical to the judgments and estimates used in the preparation of our financial statements.

Accrued research and development expenses

        As part of the process of preparing our financial statements, we are required to estimate our accrued research and development expenses at each balance sheet. This process involves reviewing open contract and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated costs incurred for the services when we have not yet been invoiced or otherwise notified of the actual costs. The majority of our service providers invoice us in arrears for services performed, on a pre-determined schedule or when contractual milestones are met; however, some require advanced payments. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us at that time. Examples of estimated accrued research and development expenses include fees paid to:

    CROs in connection with performing research activities on our behalf and conducting preclinical studies and clinical trials on our behalf;

    investigative sites or other service providers in connection with clinical trials;

    vendors in connection with preclinical and clinical development activities; and

    vendors related to product manufacturing and development and distribution of preclinical and clinical supplies.

        We base our expenses related to preclinical studies and clinical trials on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple CROs that conduct and manage preclinical studies and clinical trials on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In accruing fees, we estimate the time period over which services will be performed, enrollment of

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patients, number of sites activated and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual or amount of prepaid expense accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in us reporting amounts that are too high or too low in any particular period. To date, we have not made any material adjustments to our prior estimates of accrued research and development expenses.

Stock-based compensation

        We measure stock options and other stock-based awards granted to employees and directors based on their fair value on the date of the grant and recognize compensation expense of those awards, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award. We apply the straight-line method of expense recognition to all awards with only service-based vesting conditions and apply the graded-vesting method to all awards with performance-based vesting conditions or to awards with both service-based and performance-based vesting conditions.

        For stock-based awards granted to non-employees, compensation expense is recognized over the period during which services are rendered by such non-employees until completed in accordance with the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. The new standard largely aligns the accounting for share-based payment awards issued to employees and nonemployees by expanding the scope of ASC 718 to apply to nonemployee share-based transactions, as long as the transaction is not effectively a form of financing.

        We estimate the fair value of each stock option grant on the date of grant using the Black-Scholes option-pricing model, which uses as inputs the fair value of our common stock and assumptions we make for the volatility of our common stock, the expected term of our stock options, the risk-free interest rate for a period that approximates the expected term of our stock options and our expected dividend yield.

Determination of fair value of common stock

        As a privately held company, there has been no public market for our common stock to date, the estimated fair value of our common stock has been determined by our board of directors as of the date of each option grant, with input from management, considering our most recently available third-party valuations of common stock and our board of directors' assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of the grant. These third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants' Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Our common stock valuations were prepared using a hybrid method, which used market approaches to estimate our enterprise value. The hybrid method is a probability-weighed expected return method, or PWERM, where the equity value in one or more scenarios is calculated using an option-pricing method, or OPM. The OPM treats common stock and preferred stock as call options on the total equity value of a company, with exercise prices based on the value thresholds at which the allocation among the various holders of a company's securities changes. Under this method, the common stock has value only if the funds available for distribution to stockholders exceeded the value of the preferred stock liquidation preference at the time of the liquidity event, such as a strategic sale or a merger. The PWERM is a scenario-based methodology that estimates the fair value of common stock based upon an analysis of future values for the company, assuming various outcomes. The

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common stock value is based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes available as well as the rights of each class of stock. The future value of the common stock under each outcome is discounted back to the valuation date at an appropriate risk-adjusted discount rate and probability weighted to arrive at an indication of value for the common stock. These third-party valuations were performed at various dates, which resulted in valuations of our common stock of $0.92 per share as of May 31, 2016, $1.01 per share as of October 2, 2017 and $3.18 per share as of December 31, 2018.

        In addition to considering the results of these third-party valuations, our board of directors considered various objective and subjective factors to determine the fair value of our common stock as of each grant date, including:

    the prices at which we sold shares of preferred stock and the superior rights and preferences of the preferred stock relative to our common stock at the time of each grant;

    the progress of our research and development programs, including the status and results of preclinical studies and clinical trials for our product candidates;

    our stage of development and commercialization and our business strategy;

    external market conditions affecting the biopharmaceutical industry and trends within the biopharmaceutical industry;

    our financial position, including cash on hand, and our historical and forecasted performance and operating results;

    the lack of an active public market for our common stock and our preferred stock;

    the likelihood of achieving a liquidity event, such as an initial public offering, or IPO, or sale of our company in light of prevailing market conditions; and

    the analysis of IPOs and the market performance of similar companies in the biopharmaceutical industry.

        The assumptions underlying these valuations represented management's best estimate, which involved inherent uncertainties and the application of management's judgment. As a result, if we had used significantly different assumptions or estimates, the fair value of our common stock and our stock-based compensation expense could have been materially different.

        Once a public trading market for our common stock has been established in connection with the completion of this offering, it will no longer be necessary for our board of directors to estimate the fair value of our common stock in connection with our accounting for granted stock options and other such awards we may grant, as the fair value of our common stock will be determined based on the quoted market price of our common stock.

Options granted

        The following table summarizes by grant date the number of shares subject to options granted between January 1, 2017 and June 30, 2019, the per share exercise price of the options, the fair value

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of common stock underlying the options on each grant date, and the per share estimated fair value of the options:

Grant date
  Number of shares
subject to
options granted
  Per share
exercise price
of options
  Fair value of
common stock
per share on
date of
option grant
  Per share
estimated
fair value
of options
 

January 3, 2017

    91,456   $ 0.92   $ 0.92   $ 0.66  

February 16, 2017

    32,892   $ 0.92   $ 0.92   $ 0.67  

March 30, 2017

    185,088   $ 0.07   $ 0.92   $ 0.82  

November 24, 2017

    353,788   $ 1.01   $ 1.01   $ 0.74  

July 31, 2018

    24,067   $ 1.01   $ 1.01   $ 0.69  

February 28, 2019

    984,596   $ 3.19   $ 3.19   $ 2.23  

Income taxes

        We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in our tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Potential for recovery of deferred tax assets is evaluated by considering several factors, including estimating the future taxable profits expected, estimating future reversals of existing taxable temporary differences, considering taxable profits in carryback periods, and considering prudent and feasible tax planning strategies.

        We account for uncertain tax positions using a more-likely-than-not threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in the law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity, and changes in facts or circumstances related to a tax position. As of each balance sheet date, we did not have any uncertain tax positions.

Emerging growth company and smaller reporting company status

        We are an emerging growth company, as defined in the JOBS Act. Under this act, emerging growth companies are permitted to delay adopting new or revised accounting standards applicable to public companies until those standards would otherwise apply to private companies. We have irrevocably elected not to avail ourselves of this exemption from new or revised accounting standards and, therefore, will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

        We may remain classified as an EGC until the end of the fiscal year in which the fifth anniversary of this offering occurs, although if the market value of our common stock that is held by non-affiliates exceeds $700 million as of any June 30 before that time or if we have annual gross revenues of $1.07 billion or more in any fiscal year, we would cease to be an EGC as of December 31 of the applicable year. We also would cease to be an EGC if we issue more than $1 billion of non-convertible debt over a three-year period.

        We are also a "smaller reporting company," as such term is defined in Rule 12b-2 of the Exchange Act, meaning that the market value of our common stock held by non-affiliates plus the proposed aggregate amount of gross proceeds to us as a result of this offering is less than $700 million and our

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annual revenue is less than $100 million during the most recently completed fiscal year. We may continue to be a smaller reporting company after this offering if either (i) the market value of our common stock held by non-affiliates is less than $250 million or (ii) our annual revenue is less than $100 million during the most recently completed fiscal year and the market value of our common stock held by non-affiliates is less than $700 million. If we are a smaller reporting company at the time we cease to be an emerging growth company, we may continue to rely on exemptions from certain disclosure requirements that are available to smaller reporting companies. Specifically, as a smaller reporting company we may choose to present only the two most recent fiscal years of audited financial statements in our Annual Report on Form 10-K and, similar to emerging growth companies, smaller reporting companies have reduced disclosure obligations regarding executive compensation.

Results of operations

Comparison of the six months ended June 30, 2018 and 2019

        The following table summarizes our results of operations for the six months ended June 30, 2018 and 2019:

 
  Six months ended June 30,    
 
 
  2018   2019   Change  

Operating expenses:

                   

Research and development

  $ 7,492,788   $ 7,998,270   $ 505,482  

General and administrative

    1,166,520     2,347,915     1,181,395  

Total operating expenses

    8,659,308     10,346,185     1,686,877  

Other income (expense):

                   

Interest expense

    (188 )   (7,439 )   (7,251 )

Foreign currency gain

    949,158     1,615,974     666,816  

Total other income (expense)

    948,970     1,608,535     659,565  

Net loss

  $ (7,710,338 ) $ (8,737,650 ) $ (1,027,312 )

Research and development expenses

 
  Six months ended June 30,    
 
 
  2018   2019   Change  

APR-246

  $ 5,866,561   $ 6,314,584   $ 448,023  

Other early-stage development programs

    336,144     673,435     337,291  

Unallocated research and development expenses

    1,290,083     1,010,251     (279,832 )

Total research and development expenses

  $ 7,492,788   $ 7,998,270   $ 505,482  

        Research and development expenses for the six months ended June 30, 2018 were $7.5 million, compared to $8.0 million for the six months ended June 30, 2019. The increase of $0.5 million was primarily related to the advancement of our clinical product candidate APR-246.

General and administrative expenses

        General and administrative expenses for the six months ended June 30, 2018 were $1.2 million, compared to $2.3 million for the six months ended June 30, 2019. The increase of $1.2 million was primarily related to a $0.9 million increase in legal and accounting fees.

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Other income and expense

        Foreign currency gain for the six months ended June 30, 2018 was $0.9 million compared to $1.6 million for the six months ended June 30, 2019. The increase of $0.7 million was primarily due to a strengthening of the U.S. dollar against the Swedish Krona during the six months ended June 30, 2019. Interest expense for the six months ended June 30, 2018 and 2019 consisted of an insignificant amount of banking charges or fees and in 2019 interest expense derived from the new lease accounting.

Comparison of the years ended December 31, 2017 and 2018

        The following table summarizes our results of operations for the years ended December 31, 2017 and 2018:

 
  Years ended December 31,    
 
 
  2017   2018   Change  

Operating expenses:

                   

Research and development

  $ 13,392,631   $ 14,194,732   $ 802,101  

General and administrative

    2,459,744     2,294,671     (165,073 )

Total operating expenses

    15,852,375     16,489,403     637,028  

Other income (expense):

                   

Interest expense

    (15 )   (182 )   (167 )

Foreign currency gain

    662,140     961,316     299,176  

Total other income (expense)

    662,125     961,134     299,009  

Net loss

  $ (15,190,250 ) $ (15,528,269 ) $ (338,019 )

Research and development expenses

 
  Years ended December 31,    
 
 
  2017   2018   Change  

APR-246

  $ 9,388,373   $ 10,957,970   $ 1,569,597  

Other early-stage development programs

    1,243,991     656,692     (587,299 )

Unallocated research and development expenses

    2,760,267     2,580,070     (180,197 )

Total research and development expenses

  $ 13,392,631   $ 14,194,732   $ 802,101  

        Research and development expenses for the year ended December 31, 2017 were $13.4 million, compared to $14.2 million for the year ended December 31, 2018. The increase of $0.8 million was primarily related to the advancement of our clinical product candidate APR-246.

General and administrative expenses

        General and administrative expenses for the year ended December 31, 2017 were $2.5 million, compared to $2.3 million for the year ended December 31, 2018.

Other income and expense

        Other income and expense for the year ended December 31, 2017 consisted of an insignificant amount of banking charges or fees and a foreign currency gain of $0.7 million. Other income and expense for the year ended December 31, 2018 consisted of an insignificant amount of banking fees on our cash balances and a foreign currency gain of $1.0 million.

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Liquidity and capital resources

        Since our inception, we have incurred significant losses on an aggregate basis. We have not yet commercialized any of our product candidates, which are in various phases of preclinical and clinical development, and we do not expect to generate revenue from sales of any products for several years, if at all. To date, we have financed our operations through private placements of our preferred and common stock. Through June 30, 2019, we had received net proceeds of $136.9 million from our sales of preferred and common stock. As of June 30, 2019, we had cash, cash and cash equivalents of $61.0 million.

Cash flows

        The following table summarizes our sources and uses of cash for each of the periods presented:

 
  Years ended December 31,   Six months ended June 30,  
 
  2017   2018   2018   2019  

Net cash provided by (used in):

                         

Operating activities

  $ (14,002,118 ) $ (15,250,234 ) $ (8,246,834 ) $ (9,797,443 )

Investing activities

        (3,702 )   (4,734 )   (6,189 )

Financing activities

    23,343,863     56,366,742     1,415     5,621,480  

Net increase (decrease) in cash and cash equivalents

  $ 9,341,745   $ 41,112,806   $ (8,250,153 ) $ (4,182,152 )

    Operating activities

        The cash used in operating activities resulted primarily from our net losses adjusted for non-cash charges and changes in components of working capital. Net cash used in operating activities was $8.2 million for the six months ended June 30, 2018 compared to $9.8 million for the six months ended June 30, 2019. The increase in cash used in operating activities of $1.6 million was primarily attributable to an increase in our net loss of $1.0 million and an increase in foreign currency gains of $0.7 million.

        Net cash used in operating activities was $15.3 million for the year ended December 31, 2018 compared to $14.0 million for the year ended December 31, 2017. The increase in cash used in operating activities of $1.3 million was primarily attributable to an increase in our net loss of $0.3 million, an increase in non-cash expenses of $0.4 million, resulting primarily from an increase in foreign currency gains of $0.3 million and a decreases in stock-based compensation of $0.1 million, and a decrease in the components of working capital of $0.5 million.

    Investing activities

        During the six months ended June 30, 2019 and 2018, we used an insignificant amount of cash in investing activities, consisting of the purchase of property and equipment of $6,189 and $4,734, respectively.

        During the year ended December 31, 2018, we used an insignificant amount of cash in investing activities, consisting of the purchase of property and equipment of $3,702. There was no cash used in investing activities during the year ended December 31, 2017.

        We expect that investing activities will increase over the next several years.

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    Financing activities

        Net cash provided by financing activities was $5.6 million for the six months ended June 30, 2019 compared to $1,415 for the six months ended June 30, 2018. The increase in cash provided by financing activities of $5.6 million was primarily attributable to the issuance of Series C convertible preferred stock in February 2019 for net proceeds of $5.6 million.

        Net cash provided by financing activities was $56.4 million for the year ended December 31, 2018 compared to $23.3 million for the year ended December 31, 2017. The increase in cash provided by financing activities of $33.1 million was attributable to the issuance of Series C convertible preferred stock in November 2018 for net proceeds of $56.4 million. In October 2017, we issued Series B convertible preferred stock for net proceeds of $23.3 million.

Funding requirements

        We expect our expenses to increase substantially in connection with our ongoing development activities related to APR-246 and other product candidates and programs which are still in the early stages of clinical development. In addition, commencing upon the completion of this offering, we expect to incur additional costs associated with operating as a public company. We expect that our expenses will increase substantially if and as we:

    conduct our current and future clinical trials and additional preclinical research of APR-246;

    initiate and continue research and preclinical and clinical development of our other product candidates;

    seek to identify and develop additional product candidates;

    seek marketing approvals for any of our product candidates that successfully complete clinical trials, if any;

    establish a sales, marketing, manufacturing and distribution infrastructure to commercialize any products for which we may obtain marketing approval;

    require the manufacture of larger quantities of our product candidates for clinical development and potentially commercialization;

    maintain, expand, protect and enforce our intellectual property portfolio;

    acquire or in-license other drugs and technologies;

    defend against any claims of infringement, misappropriation or other violation of third-party intellectual property;

    hire and retain additional clinical, quality control and scientific personnel;

    build out new facilities or expand existing facilities to support our ongoing development activity;

    add operational, financial and management information systems and personnel, including personnel to support our drug development, any future commercialization efforts and our transition to a public company; and

    operate as a public company.

        As of June 30, 2019, we had cash and cash equivalents of $61.0 million. We believe that the anticipated net proceeds from this offering, together with our existing cash and cash equivalents, will enable us to fund our operating expenses and capital expenditure requirements into 2023. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect.

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        Because of the numerous risks and uncertainties associated with the development of APR-246 and other product candidates and programs and because the extent to which we may enter into collaborations with third parties for development of our product candidates is unknown, we are unable to estimate the timing and amounts of increased capital outlays and operating expenses associated with completing the research and development of our product candidates. Our future capital requirements will depend on many factors, including:

    the scope, progress, results and costs of our current and future clinical trials of APR-246 for our current targeted indications;

    the scope, progress, results and costs of drug discovery, preclinical research and clinical trials for APR-246 and our other product candidates;

    the number of future product candidates that we pursue and their development requirements;

    the costs, timing and outcome of regulatory review of our product candidates;

    the extent to which we acquire or invest in businesses, products and technologies, including entering into or maintaining licensing or collaboration arrangements for product candidates on favorable terms, although we currently have no commitments or agreements to complete any such transactions;

    the costs and timing of future commercialization activities, including drug sales, marketing, manufacturing and distribution, for any of our product candidates for which we receive marketing approval, to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time;

    the amount of revenue, if any, received from commercial sales of our product candidates, should any of our product candidates receive marketing approval;

    the costs of preparing, filing and prosecuting patent applications, maintaining, protecting and enforcing our intellectual property rights and defending intellectual property-related claims;

    our headcount growth and associated costs as we expand our business operations and our research and development activities; and

    the costs of operating as a public company.

        Developing drug products, including conducting preclinical studies and clinical trials, is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval for any product candidates or generate revenue from the sale of any products for which we may obtain marketing approval. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of drugs that we do not expect to be commercially available for many years, if ever. Accordingly, we will need to obtain substantial additional funds to achieve our business objectives.

        Adequate additional funds may not be available to us on acceptable terms, or at all. We do not currently have any committed external source of funds. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest may be diluted, and the terms of these securities may include liquidation or other preferences and anti-dilution protections that could adversely affect your rights as a common stockholder. Additional debt or preferred equity financing, if available, may involve agreements that include restrictive covenants that may limit our ability to take specific actions, such as incurring debt, making capital expenditures or declaring dividends, which could adversely impact our ability to conduct our business, and may require the issuance of warrants, which could potentially dilute your ownership interest.

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        If we raise additional funds through collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our technology, future revenue streams, research programs, or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings or collaborations, strategic alliances or licensing arrangements with third parties when needed, we may be required to delay, limit, reduce and/or terminate our product development programs or any future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Contractual obligations and commitments

        The following table summarizes our contractual obligations at June 30, 2019:

 
  Payments due by period  
 
  Total   Less than
1 year
  1 - 3 years   3 - 5 years   More than
5 years
 

Operating leases(1)

  $ 310,973   $ 122,783   $ 188,190   $   $  

Total

  $ 310,973   $ 122,783   $ 188,190   $   $  

(1)
Represents minimum payments due for our lease of office and laboratory space in Boston, Massachusetts under an operating lease agreement that, as amended, expires in 2021.

        We enter into contracts in the normal course of business with CROs and CMOs for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. These contracts do not contain any minimum purchase commitments and are cancelable by us upon prior notice of 30 days and, as a result, are not included in the table of contractual obligations above. Payments due upon cancelation consist only of payments for services provided and expenses incurred up to the date of cancelation.

Internal control over financial reporting

        In connection with the audit of our financial statements, we and our independent registered public accounting firm identified a material weakness in our internal control over financial reporting primarily related to the lack of sufficient skilled employees with U.S. GAAP and SEC reporting knowledge and experience for the purposes of timely and reliable financial reporting. A material weakness is a deficiency, or combination of deficiencies, in internal control over financial reporting such that there is a reasonable possibility that a material misstatement of our annual or interim financial statements will not be prevented or detected and corrected on a timely basis. We are currently establishing more robust processes to strengthen our internal control over financial reporting. See "Risk Factors—In connection with the preparation of our financial statements as of and for the years ended December 31, 2017 and 2018, the Company and our independent registered public accounting firm identified a material weakness in the Company's internal control over financial reporting. If we are not able to remediate the material weakness and otherwise to maintain an effective system of internal control over financial reporting in the future, investors may lose confidence in the accuracy and completeness of our financial reports, and the market price of our common stock could be materially and adversely affected."

        We are working to remediate the material weakness and are taking steps to strengthen our internal control over financial reporting, such as, for example, the recent hiring of Scott M. Coiante as Chief Financial Officer. Additionally, we plan to further develop and implement formal policies, processes and documentation procedures relating to the financial reporting of the Company. The actions that we are taking are subject to ongoing executive management review, and will also be subject to audit committee oversight.

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Off-balance sheet arrangements

        We did not have during the periods presented, and we do not currently have, any off-balance sheet arrangements, as defined in the rules and regulations of the SEC.

Recently issued accounting pronouncements

        We have reviewed all recently issued standards and have determined that, other than as disclosed in Note 2 to our financial statements appearing at the end of this prospectus, such standards will not have a material impact on our financial statements or do not otherwise apply to our operations.

Quantitative and qualitative disclosures about market risk

Interest Rate Risk

        We are exposed to market risk related changes in interest rates. As of June 30, 2019, our cash equivalents consisted of bank deposits and money market accounts. Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of U.S. interest rates. However, historical fluctuations in interest income have not been significant for us.

Foreign Currency Exchange Rate Risk

        We face market risk to the extent that changes in foreign currency exchange rates affect our non-U.S. dollar functional currency foreign subsidiaries' revenues, expenses, assets and liabilities. The financial position and results of operations of our subsidiaries Aprea AB and Aprea Personal AB are measured using the foreign subsidiaries' local currency as the functional currency. Aprea AB cash accounts holding U.S. dollars are remeasured based upon the exchange rate at the date of remeasurement with the resulting gain or loss included in the consolidated statement of operations and comprehensive loss.

        Our investments in foreign subsidiaries with a functional currency other than the U.S. dollar are generally considered long-term. In addition, we do not believe that we currently have any significant direct foreign exchange risk. Accordingly, we have not used any derivative financial instruments to hedge exposure to such risk.

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Business

Overview

        We are a clinical-stage biopharmaceutical company focused on developing and commercializing novel cancer therapeutics that reactivate mutant p53 tumor suppressor protein. p53 is the protein expressed from the TP53 gene, the most commonly mutated gene in cancer. We believe that mutant p53 is an attractive therapeutic target due to the high incidence of p53 mutations across a range of cancer types and its involvement in key cellular activities such as apoptosis. Cancer patients with mutant p53 face a significantly inferior prognosis even when treated with the current standard of care, and a large unmet need for these patients remains. Our lead product candidate, APR-246, is a small molecule p53 reactivator that is in late-stage clinical development for hematologic malignancies, including myelodysplastic syndromes, or MDS, and acute myeloid leukemia, or AML. APR-246 has received Orphan Drug and Fast Track designations from the FDA for MDS, and Orphan Drug designation from the EMA for MDS, AML and ovarian cancer, and we believe APR-246 will be a first-in-class therapy if approved by applicable regulators. We have commenced a pivotal Phase 3 trial of APR-246 with azacitidine for frontline treatment of TP53 mutant MDS and expect initial data from this trial in the second half of 2020. Our pivotal Phase 3 trial is supported by data from two ongoing Phase 1b/2 investigator initiated trials, one in the U.S. and one in France, testing APR-246 with azacitidine as frontline treatment in TP53 mutant MDS and AML patients.

        In the ongoing U.S. Phase 1b/2 trial, sponsored by Dr. David Sallman of the H. Lee Moffitt Cancer Center and Research Institute, or Moffitt, we have observed an objective response rate, or ORR, of 88% and a complete remission, or CR, rate of 59% in 41 response-evaluable MDS/AML patients treated with APR-246 and azacitidine, as of July 2019 and we expect a final CR endpoint in the second half of 2019. In MDS patients, the CR rate was 61%, with an additional 27% achieving non-CR responses. In AML patients, the CR rate was 50%, with an additional 38% achieving non-CR responses. In addition, 46% of evaluable patients were able to discontinue treatment in order to proceed to allogeneic hematopoietic stem cell transplantation, or allo-HCT. Allo-HCT is currently the only recognized therapy believed to increase the likelihood of long term survival for TP53 mutant MDS and AML patients in remission. In the ongoing French Phase 1b/2 trial, sponsored by Groupe Francophone des Myelodysplasies, or GFM, under lead investigator Prof. Pierre Fenaux, we have observed an ORR of 75% and a CR rate of 56% in 16 response-evaluable patients treated with APR-246 and azacitidine, as of July 2019 and we expect a final CR endpoint in the first half of 2020. In MDS patients, the CR rate was 55%, with an additional 18% achieving non-CR responses. In AML patients, the CR rate was 60%, with an additional 20% achieving non-CR responses. We expect the results of our pivotal Phase 3 trial and the U.S. and French Phase 1b/2 trials will be submitted in support of marketing applications to the FDA and EMA. We are also developing a next-generation small molecule p53 reactivator, APR-548, for potential use in multiple hematologic malignancies and other oncologic indications, and expect to file an IND with the FDA in the first half of 2020. We have assembled a management team with extensive experience in the discovery and development of novel oncology drugs. Our management team is supported by our world-class scientific advisors and leading life science investors in their mission to successfully develop p53-reactivating therapies for cancer patients.

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        Our lead programs are summarized below. We currently retain global development and commercialization rights to all of our product candidates:

GRAPHIC


(1)
Investigator-initiated trial

(2)
With or without azacitidine

        We believe that targeting p53 and thereby reactivating key intrinsic cellular functions has the potential to significantly impact patients' lives and treatment strategies for a wide variety of cancers. p53 is a tumor suppressor protein that in its normal state functions to sense DNA damage and induce cell cycle arrest, DNA damage repair, senescence and cellular apoptosis. Mutant p53 is an attractive target because it is widely mutated across hematologic and solid tumors and is associated with an aggressive clinical and molecular phenotype. In preclinical studies and clinical trials, mutations in p53 and the apoptotic pathway have been shown to play a key role in cancer genesis, proliferation and resistance to currently marketed therapeutic agents. Many approved and clinical stage oncology drugs are more effective with a functional p53 pathway. Our approach is to restore normal function to p53, thereby re-enabling a cell's ability to undergo apoptosis. Accordingly, we believe that by targeting p53, our drug candidates may enhance the ability of other anti-cancer therapies to induce cancer cell death. In addition, we believe that our approach may counteract resistance mechanisms that characterize many of the most aggressive cancers. Although we have observed single agent activity in preclinical testing of APR-246, our current clinical program is focused on combination therapy based on the strong additive or synergistic effects we have observed in combination with multiple conventional chemotherapeutic drugs, DNA hypomethylating agents, or HMAs, inhibitors of anti-apoptotic proteins and immuno-oncology checkpoint blockade agents.

        Our lead product candidate, APR-246, is a small molecule that has demonstrated reactivation of mutant p53 in clinical trials. Promising clinical data support the application of APR-246 across a variety of hematologic malignancies and other oncologic indications. APR-246 is a pro-drug that is administered intravenously and forms the active moiety, 2-methylene-quinuclidin-3-one, or MQ, under

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physiological conditions. APR-246 has been shown to induce apoptosis in cancer cells with mutant p53 in Phase 1/2 trials. We believe the mechanism of action and current adverse event profile of APR-246 may provide the basis for its combination with both conventional and novel therapies, such as targeted therapies, chemotherapy, radiotherapy and immuno-therapy. APR-246 has received Orphan Drug and Fast Track designations from the FDA for MDS, and Orphan Drug designation from the EMA for MDS, AML and ovarian cancer.

        We are conducting and supporting multiple clinical trials of APR-246:

    Pivotal Phase 3 MDS Trial—We are currently enrolling a pivotal Phase 3 randomized, controlled trial evaluating APR-246 with azacitidine as frontline therapy in HMA-naïve TP53 mutant MDS patients. The trial has a target enrollment of 154 patients randomized in a 1:1 ratio to either the azacitidine control arm or to the APR-246 + azacitidine experimental arm, with a primary endpoint of CR rate. The first patient was enrolled in January 2019 and we anticipate full enrollment in our Phase 3 trial in the first quarter of 2020 and top-line data from this trial in the second half of 2020.

    U.S. Phase 1b/2 MDS/AML Trial—We are supporting an investigator-initiated Phase 1b/2 single-arm, open-label trial in the United States, sponsored by Dr. David Sallman of the H. Lee Moffitt Cancer Center and Research Institute, or Moffitt, evaluating APR-246 with azacitidine as frontline therapy in HMA-naïve patients with TP53 mutant MDS or AML. We are collaborating with Moffitt on this trial by supplying APR-246, in addition to providing financial support. The primary endpoint of the trial is CR rate and enrollment has completed with 55 patients. Top-line results on the CR rate primary endpoint and median duration of response are expected in the second half of 2019. The regimen achieved an ORR of 88% and a CR rate of 59% in 41 response-evaluable patients as of July 2019. In MDS patients, the CR rate was 61%, with an additional 27% achieving non-CR responses. In AML patients, the CR rate was 50%, with an additional 38% achieving non-CR responses. In addition, 46% of evaluable MDS/AML patients were able to discontinue treatment in order to proceed to allo-HCT. By intention-to-treat analysis, and with a median follow up of 10.5 months, median OS was 11.6 months (95% confidence interval: 9.2 – 14.0 months) with significantly prolonged OS of 12.8 months in responding patients versus 3.9 months in non-responding patients (p < 0.0001). Analysis of peer-reviewed published data in TP53 mutant MDS and AML suggests frontline azacitidine monotherapy provides an ORR of 40-50% for AML, CR rates of approximately 20% and median OS of 7-8 months.

    French Phase 1b/2 MDS/AML Trial—We are supporting a parallel investigator-initiated Phase 1b/2 single-arm, open-label trial in France, sponsored by Groupe Francophone des Myelodysplasies, or GFM, under lead investigator Prof. Pierre Fenaux, evaluating APR-246 with azacitidine as frontline therapy in HMA-naïve patients with TP53 mutant MDS or AML. We are collaborating with GFM on this trial by supplying APR-246, in addition to providing financial support. The primary endpoint of the trial is CR rate and enrollment has completed with 53 patients. Top-line results on the CR rate primary endpoint are expected in the first half of 2020. All patients are to receive the recommended Phase 2 dose from the U.S. Phase 1b/2 MDS/AML Trial. As of July 2019, the regimen has achieved an ORR of 75% and CR rate of 56% in 16 response-evaluable patients. In MDS patients, the CR rate was 55%, with an additional 18% achieving non-CR responses. In AML patients, the CR rate was 60%, with an additional 20% achieving non-CR responses. Responding patients who proceed to allo-HCT are eligible to continue receiving APR-246 with azacitidine as post-transplant maintenance therapy.

    Phase 2 MDS/AML Post-Transplant Trial—We are currently enrolling our single-arm, open-label Phase 2 trial evaluating APR-246 with azacitidine as post-transplant maintenance therapy in TP53 mutant MDS and AML patients who have received allo-HCT. The primary endpoint is

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      relapse-free survival at 12 months. Target enrollment is 31 patients and we anticipate full enrollment in the second half of 2020. Analysis of the historical, peer-reviewed published data in TP53 mutant MDS and AML patients who undergo bone marrow transplant suggests that TP53 mutation is associated with a 4-fold increased risk of death following transplantation and a 1-year relapse-free survival of only 30%.

    Phase 1/2 AML Trials—Based on in vitro data evidencing synergistic activity between APR-246 and a Bcl-2 inhibitor, we have designed and plan to conduct Phase 1/2 clinical trials in frontline and relapsed/refractory AML assessing APR-246 with a Bcl-2 inhibitor with or without azacitidine. We anticipate the first patient to be enrolled in the fourth quarter of 2019.

        Our second product candidate, APR-548, is a next-generation p53 reactivator with the potential for oral administration. APR-548 is a unique analog of APR-246 and therefore a pro-drug of MQ. APR-548 exhibits high oral bioavailability in preclinical testing and is being developed in an oral dosage form. We are currently conducting Investigational New Drug, or IND, enabling preclinical studies of APR-548 and anticipate submitting an IND in the first half of 2020.

        We have assembled an outstanding team, which includes world-class scientific and clinical oncology leaders, to execute on our mission to create novel p53-reactivating therapies to help patients suffering with cancer. Together with our board of directors, our scientific founders and members of our management team have significant experience in drug discovery and development and finance. Collectively, we believe our team's strong capabilities position us to build a leading biotech company focused on developing novel cancer therapies to address the significant unmet medical need of patients with p53 mutant malignancies, for whom there are limited effective therapeutic options.

Our strategy

        Our mission is to be the leading player in the development and commercialization of p53-targeted cancer therapies. The key elements of our strategy are to:

    Rapidly develop and commercialize our lead mutant p53 reactivator, APR-246, in frontline combination therapy for TP53 mutant MDS. We are currently advancing APR-246 with azacitidine through Phase 3 clinical development in TP53 mutant MDS. We are initially targeting frontline TP53 mutant MDS, where there are few approved therapies, no approved p53-targeted therapies and a continued high unmet medical need. We believe the data generated to date support compelling clinical activity in this underserved patient population.

    Expand the clinical opportunity for APR-246 by pursuing development of combination therapy for post-transplant maintenance in TP53 mutant MDS and AML. Allo-HCT is currently considered the only curative option for patients with TP53 mutant MDS/AML, and even with transplantation the outcomes for these patients remain poor. We are currently advancing APR-246 as post-transplant maintenance therapy in TP53 mutant MDS and AML in the French Phase 1b/2 MDS/AML Trial and our Phase 2 MDS/AML Post-Transplant Trial. We believe that this approach may offer an opportunity to quickly expand the commercial potential of APR-246.

    Rapidly develop APR-246 for frontline and relapsed/refractory TP53 mutant AML.  We are currently advancing the clinical development of APR-246 in frontline TP53 mutant AML through the U.S. Phase 1b/2 MDS/AML Trial and the French Phase 1b/2 MDS/AML Trial. While these frontline trials are evaluating APR-246 with azacitidine, we also intend to evaluate additional combination regimens with a Bcl-2 inhibitor with or without azacitidine in both frontline and relapsed/refractory AML patients. We believe that the treatment of these patients may offer an opportunity to significantly expand the commercial potential of APR-246.

    Advance our next-generation p53 reactivator, APR-548.  We are developing a next-generation small molecule p53 reactivator with the potential to be delivered in an oral dosage form. We intend to

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      initially develop APR-548 in TP53 mutant MDS/AML. We believe that an oral p53-reactivating drug will improve patient convenience and compliance, if approved, including for patients receiving prolonged therapy in the maintenance setting.

    Explore additional oncology indications for APR-246 and APR-548.  We are evaluating combination treatment with our product candidates in additional hematologic and solid tumor indications where mutant and dysfunctional p53 is a driver of disease. We have preclinical models that show synergistic effects of APR-246 with a variety of anti-cancer agents including multiple conventional chemotherapeutic drugs, HMAs, inhibitors of anti-apoptotic proteins and immuno-oncology checkpoint blockade agents. Based on our preclinical data, we believe there is potential to expand APR-246 and APR-548 into additional oncological indications.

    Maximize the commercial opportunity of our product candidates across global markets.  We currently retain worldwide development and commercialization rights to all of our product candidates. We intend to retain commercial rights to our product candidates in the United States and may elect to build a focused commercial oncology organization to market any of our product candidates that are approved. Outside of the United States, we may elect to selectively evaluate strategic partnership opportunities for our product candidates with partners whose development and commercial capabilities complement our own.

Our approach

Background on p53, a key tumor suppressor protein

        TP53 is the most widely mutated gene in human cancers. Since its discovery in 1979, p53 has been extensively studied by researchers and the pharmaceutical industry due to its central role in preventing the initiation and progression of liquid and solid tumors. p53 has long been referred to as "the guardian of the genome" because it is the body's first line of cellular defense against cancers. Among its multiple biologic functions, p53 regulates a variety of tumor suppressive responses including cell cycle arrest, DNA repair, apoptosis, and senescence.

        p53 is activated when DNA damage is detected and when oxidative or other cellular stresses exceed thresholds for normal cellular function. The result of p53 activation is to facilitate the repair of the cell or trigger killing of the damaged cell, through a process known as apoptosis, before it can become cancerous and replicate. Given that the mutational status of p53 in a tumor has a strong impact on sensitivity to commonly used anti-cancer drugs and radiotherapy, p53 is important both as clinical marker and as a novel therapeutic target. Importantly, mutations in p53 not only diminish tumor suppression function but also often lead to the acquisition of new pro-tumor functions.

        To date, more than 25,000 unique TP53 mutations have been reported and thus a key challenge in the development of p53-targeted therapies is the vast number of mutations that compromise tumor suppression activity. Incidence of TP53 mutations increases after treatment with chemotherapy or radiation. The most common of these are missense mutations, involving the site-specific exchange of one amino acid for another, and account for 75% of all p53 mutations; however, even the six most frequently mutated "hotspot" missense mutations in p53 collectively represent only ~30% of all missense mutations. Therefore, we believe that a therapeutic agent that targets a small subset of TP53 mutations would be of limited benefit. To circumvent these challenges, previous drug development efforts have primarily focused on gene therapy delivery of wild type p53 or drugs that disrupt interaction with proteins that control p53 activation and abundance. We believe the more effective approach is our direct conformational reactivation of mutant p53 and restoration of wild-type structure and activity, independent of the type of mutation.

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Our approach to re-activating p53

        One of the most attractive features of apoptosis activation as a cancer therapy is its potential to induce tumor regression rather than to simply stop tumor growth. However, pro-apoptotic agents that cannot discriminate between malignant and normal cells carry a significant risk of side effects. This is an important issue with traditional cancer treatments: radiotherapy and chemotherapy induce apoptosis only as a secondary effect of the cellular damage they induce. These treatments affect most proliferating cells without distinction between malignant or normal cells. Our product candidates, in contrast, are designed to reactivate mutant, non-functional p53 to restore normal apoptotic functions in cancer cells without triggering apoptosis in normal cells, thereby selectively enhancing the effects of other chemotherapy drugs in malignant cancer cells with mutant p53.

        APR-246 and the MQ, have been extensively studied. MQ-modified mutant p53 protein has been shown to induce significant levels of apoptosis, indicating that covalent binding of MQ activates mutant p53 and induces a p53-dependent apoptotic response. Experiments by our founders looking directly at the conformational state of p53 protein in cells have confirmed that binding of MQ stabilizes mutant p53 in the functional, wild type conformation. Structural biology studies performed by our collaborators have produced the first-ever crystal structures of several single-site missense mutant p53 forms bound to DNA. These structures confirm both the sites of MQ binding to mutant p53 and the stabilization of mutant p53 by MQ in the wild type conformation. Reactivation of mutant p53 via stabilization of the properly folded wild type conformation is the key step in our product candidates' mechanism of action. The following diagram illustrates this mechanism.

GRAPHIC

        In in vitro and in vivo experiments, our lead p53 re-activating product candidate, APR-246, via MQ, impaired tumor cells' capacity to respond to oxidative stress. In parallel to binding mutant p53, and as published by Liu et al, Nat Commun, 2017, 14844, MQ depletes intracellular glutathione, or GSH, and induces reactive oxygen species, or ROS. Furthermore, as published in Peng et al, Cell Death Dis, 2013, e881, MQ has been shown to inhibit the reductase activities of the redox enzyme thioredoxin reductase, or TrxR1, and convert the enzyme to a dedicated oxidase, thereby increasing levels of ROS. Additional results reported in Haffo et al, Sci. Reports, 2018, 12671, have demonstrated MQ inhibition of thioredoxin, or Trx1, and glutaredoxin, or Grx1, which further augment oxidative stress, and ribonucleotide reductase, or RNR, which decreases the cell's ability to repair damaged DNA. These effects on the cellular redox system, illustrated in the following diagram, may contribute to the anticancer activity of APR-246 as well as the selectivity for effects on cancer cells versus healthy normal cells. Malignant cells have higher levels of ROS than healthy cells and are thus more

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susceptible to increased stress that can trigger pro-apoptotic responses. MQ-induced oxidative stress is therefore an important secondary feature of the mechanism of action.

GRAPHIC

        Cell fate is a function of the extent and severity of cellular stresses, such as oxidative stress and DNA damage. A network of proteins translates information about cellular stress into biochemical signals and relays this information back to p53, the center of the network. p53 integrates these biochemical signals and becomes activated to initiate cell cycle arrest. When cellular stress and damage are sufficiently high, such as with chemotherapy, p53 initiates apoptosis. MQ restores the ability of a cell to respond to oxidative stress and DNA damage via reactivation of mutant p53 and induces heightened oxidative stress signals to which reactivated p53 can respond. The overlap of these features of the mechanism of action may in turn provide more efficient induction of apoptosis.

Market opportunity for p53 re-activating product candidates

        We believe there is a significant market opportunity for therapies targeting mutant p53 because these mutations occur in more than half of all tumors and confer an inferior prognosis relative to patients with wild type p53. Preclinical anti-tumor activity has been observed with APR-246 in a wide variety of hematological and solid tumor models and cell lines as reviewed and referenced in Perdrix et al, Cancer 2017, 9, 172. Given the importance of p53 mutations as disease-driver mutations, the sensitivity of hematopoietic cells to oxidative stress and continued unmet medical need, we are initially focused in our clinical development on hematological malignancies, MDS and AML, with TP53 mutations.

    Myelodysplastic syndromes—disease background and opportunity

        MDS is a collection of bone marrow disorders in which malignant hematopoietic cells prevent production of healthy, mature blood cells. Low blood cell counts, called cytopenias, are a hallmark feature of MDS and are a principal cause of morbidity and mortality from infection and bleeding. MDS can develop de novo or may arise secondary to chemotherapy or radiation treatment for a different, prior malignancy or following an antecedent hematological disorder. Treatment-related MDS is associated with increased complex chromosomal abnormalities and carries a worse prognosis than de novo MDS. As of 2019, there are an estimated 200,000 MDS patients worldwide, with 68,000 of these in the United States and 69,000 MDS patients across the five major markets of the European Union and Japan. Globally, MDS prevalence is expected to increase 2-3% annually in mature markets and 3-4% annually in emerging markets as populations age. MDS predominantly affects older adults, with

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approximately 75% of patients aged 60 years or older at diagnosis. Around 30% of patients diagnosed with MDS will progress to AML, with the rate being higher for patients with more advanced disease.

        MDS patients are segmented into different risk groups according the number of cytopenias, bone marrow blast percentage, and cytogenetic abnormalities. The presence of three or more coincident structural genetic abnormalities is classified as a complex karyotype, which correlates with poor prognosis, low response to intensive chemotherapy, high rate of relapse and inferior survival. Mutations in TP53 occur in approximately 20% of patients with de novo MDS and in more than 30% of patients with therapy-related MDS who develop disease secondary to chemotherapy or radiation treatment for other cancers. Sequencing of a panel of commonly mutated genes, including TP53, is standard practice in the diagnosis of MDS.

        Historically, treatment response rates in TP53 mutant MDS patients have been poor regardless of therapy. Treatment with azacitidine is the standard of care for frontline therapy in TP53 mutant MDS, with ORR of 40-45%, a CR rate of 20% and median OS of approximately 7-8 months. There are no established curative pharmacologic therapies for MDS. Allo-HCT is currently the only recognized therapy believed to increase the likelihood of long term survival for TP53 mutant MDS patients; however, many patients are not candidates for allo-HCT due to lack of sufficient clinical response to initial therapy, advanced age, comorbidities or lack of a suitable donor. Unfortunately, even for those TP53 mutant MDS patients who receive allo-HCT, the post-transplantation prognosis is poor: TP53 mutations are associated with a 4-fold increased risk of death and 1-year relapse-free survival of only 30% following transplantation.

        Given the poor prognosis for patients with TP53 mutant MDS there is a significant need for more effective therapies in this population, particularly if such treatments have a favorable safety profile, and a mechanism of action that targets mutant p53 directly, and may be used in combination with existing or future treatment options.

    Acute myeloid leukemia—disease background and opportunity

        AML is the most common form of adult leukemia, with the highest incidence in patients aged 60 years and older. AML is characterized by proliferation of abnormal immature white blood cells which, like MDS, impairs production of normal blood cells. AML can develop de novo or may arise secondary to progression of other hematologic disorders or from chemotherapy or radiation treatment for a different, prior malignancy; secondary AML carries a worse prognosis than de novo AML. As of 2019, there are an estimated 213,000 AML patients worldwide, with 37,000 of these in the United States and 41,000 across the five major European Union markets and Japan. Globally, AML prevalence is expected to increase approximately 1-2% annually in mature markets and 2-3% in emerging markets.

        AML patients are segmented into different risk groups according to cytogenetic abnormalities. The presence of three or more coincident structural genetic abnormalities is classified as a complex karyotype, which correlates with adverse prognosis, low response to intensive chemotherapy, high rate of relapse and inferior survival. Mutations in TP53 occur in approximately 20% of patients with newly diagnosed AML, more than 30% of patients with therapy-related AML and approximately 70-80% of patients with complex karyotype. Sequencing of a panel of commonly mutated genes, including TP53, is standard practice in the diagnosis of AML.

        Historically, treatment response rates in TP53 mutant AML patients have been poor regardless of therapy. Treatment with azacitidine is the standard of care therapy for frontline therapy in TP53 mutant AML, with 40-50% ORR, 10-20% CR rate and OS of 7-8 months. Similar to MDS, allo-HCT is currently the only recognized therapy believed to increase the likelihood of long term survival for TP53 mutant AML patients; however, many patients are not candidates for allo-HCT due to lack of sufficient clinical response to therapy, advanced age, comorbidities or lack of a suitable donor. Unfortunately, even for those TP53 mutant AML patients who receive allo-HCT, the post-transplantation prognosis is

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poor: TP53 mutations are associated with a 4-fold increased risk of death and 1-year relapse-free survival of only 30% following transplantation.

        Given the poor prognosis for patients with TP53 mutant AML there is a significant need for more effective therapies in this population, particularly if such treatments have a favorable safety profile, and a mechanism of action that targets mutant p53 directly, and may be used in combination with existing or future treatment options.

Our lead product candidate, APR-246

        Our lead product candidate, APR-246, is a small molecule that has demonstrated reactivation of mutant p53 in both clinical trials and preclinical studies. Promising clinical and preclinical data support the application of APR-246 across a variety of hematologic malignancies and other oncologic indications. Based on its mechanism of action of p53 reactivation and the complementary increase in oxidative stress, as well as its potential synergy with anti-cancer agents as evidenced in preclinical studies, APR-246 treatment may be effective in a broad range of clinical settings. We are currently focusing our clinical development of APR-246 on hematologic malignancies.

Clinical trials of APR-246 in MDS and AML

        We are currently evaluating APR-246 with azacitidine for the treatment of TP53 mutant MDS and/or AML patients in 4 clinical trials, including frontline therapy and post-allo-HCT maintenance therapy. We plan to initiate an additional trial in the fourth quarter of 2019 to evaluate APR-246 with a Bcl-2 inhibitor with or without azacitidine for the treatment of frontline and relapsed/refractory, or R/R, AML.

    The Pivotal Phase 3 MDS Trial

        Our pivotal Phase 3 trial commenced enrollment in January 2019. Patients are randomized in a 1:1 ratio to either the azacitidine control arm or to the APR-246 + azacitidine test arm. The primary endpoint is CR rate with secondary endpoints including ORR, duration of response, progression-free survival, or PFS, leukemia-free survival, or LFS, OS, and proportion transitioning to allo-HCT. Serious adverse events, regardless of causality, reported in more than one patient as of September 18, 2019 were: febrile neutropenia 19%, lung infection (9%), pyrexia 6%, muscle weakness 4%, pericarditis 4%, pneumonitis 4%, hypotension (4%), sepsis (4%). There has been one death, resulting from respiratory failure, in a patient receiving both APR-246 and azacitidine and reported by an investigator as possibly related to both study drugs. There has been one death, resulting from pneumonitis, in a patient receiving azacitidine monotherapy and reported by an investigator as possibly related. The target enrollment is 154 patients and we anticipate completing enrollment in the first quarter of 2020 and expect top-line CR data in the second half of 2020.

    The U.S. Phase 1b/2 MDS/AML Trial

        We are supporting an investigator-initiated Phase 1b/2 single-arm, open-label, multi-center trial in the United States of APR-246 with azacitidine in HMA-naïve patients with TP53 mutant myeloid neoplasms including MDS and AML. Enrollment commenced in May 2017 and was completed in March 2019. The Phase 1b part enrolled 12 patients and was conducted as a dose escalation in a modified 3+3 design at dose levels of 50 mg/kg/d, 75 mg/kg/d and 100 mg/kg/d, calculated by lean body mass. The Phase 2 part enrolled 43 patients with all patients receiving a fixed dose of 4500 mg/d APR-246, a dose that our population pharmacokinetic analysis has identified as approximately equivalent to the highest Phase 1b dose, 100 mg/kg/d by lean body mass. A lead-in phase, beginning two weeks prior to starting cycle 1 of combination therapy with azacitidine, was conducted only in the Phase 1b part. The purpose of the lead-in phase was to establish the adverse event profile of APR-246 in this patient population and to APR-246-induced p53 reactivation. The protocol specifies administration of APR-246 as a 6-hour intravenous infusion daily for four consecutive days, with administration of 75 mg/m2/d azacitidine by sub-cutaneous injection or intravenously beginning on Day 4 after completion of APR-246 infusion and continuing for 6 additional days. The image below shows the design of the U.S. Phase 1b/2 MDS/AML Trial.

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Design of the U.S. Phase 1b/2 MDS/AML Trial

GRAPHIC

        Baseline characteristics of patients enrolled in the trial are shown in the following table. Patients with MDS, AML, chronic myelomonocytic leukemia, or CMML, and MDS-myeloproliferative neoplasm overlap, or MDS-MPN, were allowed to enroll in the trial. Most patients were higher risk MDS (35/55, 64%) or AML (11/55, 20%), with complex karyotypes, cytopenias and transfusion dependence.

Baseline characteristics

 
  All patients (n=55)

Female / Male, n

  29 / 26

Age in years, median (range)

  66 (34 - 85)

Age Category, n (%)

   

< 65

  23 (42)

³ 65

  32 (58)

ECOG PS(1) at treatment start, n (%)

   

0

  17 (31)

1

  34 (62)

2

  4 (7)

Disease type, n (%)

   

MDS

  40 (73)

IPSS-R(2): Intermediate

  4 (7)

IPSS-R: High

  8 (15)

IPSS-R: Very High

  28 (51)

AML

  11 (20)

CMML(3)

  2 (4)

MDS-MPN(4)

  2 (4)

Therapy-related(5), n (%)

  18 (33)

Chemotherapy

  16 (29)

Radiation

  3 (5)

Complex karyotype, n (%)

  47 (85)

TP53 VAF(6)%, median (range)

  27 (1 - 79)

Bone marrow blast %, median (range)

  8 (0 - 30)

Hematology, median (range)

   

ANC(7), 103/mL

  1.19 (0.02 - 15.98)

Hgb(8), g/dL

  8.6 (6.7 - 13.8)

Platelets, 103/mL

  46 (0 - 845)

WBC(9), 103/mL

  2.4 (0.6 - 30.8)

Transfusion dependence, n (%)

   

RBC(10)

  36 (65)

Platelets

  12 (22)

(1)
Eastern Cooperative Oncology Group performance status

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(2)
Revised International Prognostic Scoring System

(3)
Chronic myelomonocytic leukemia

(4)
Myelodysplastic syndromes-myeloproliferative neoplasms overlap

(5)
Patients treated for prior cancer(s)

(6)
Variant allele frequency

(7)
Absolute neutrophil count

(8)
Hemoglobin

(9)
White blood cell

(10)
Red blood cell

        The median age of all enrolled patients was 66 years, consistent with MDS and AML affecting mostly older patients. Of the MDS patients in the trial, 36/40 were high or very high risk by IPSS-R. Across all patients, 33% had documented therapy-related disease and 85% had complex karyotypes. High risk patients with complex karyotypes and TP53 mutation have been reported to have the poorest prognosis of all MDS and AML patients. The median bone marrow blast percentage was 8%. Hematologic parameters were reflective of the frequently severe cytopenias attendant with MDS and AML, and were underscored by transfusion dependence at baseline in 65% of patients.

        Of the 51 MDS and AML patients treated with the combination of APR-246 and azacitidine, 41 had at least one serial bone marrow biopsy performed and were evaluable for response in accordance with trial protocol as of July 2019. In this subset of 41 evaluable patients, responses were reported in 29/33 (88%) MDS patients and 7/8 (88%) AML patients. In MDS patients, the CR rate was 61%, with an additional 27% achieving non-CR responses. In AML patients, the CR rate was 50%, with an additional 38% achieving non-CR responses. Nineteen of 41 (46%) MDS/AML patients discontinued treatment for allo-HCT, as transplant is viewed as a potentially curative option for patients with TP53 mutant MDS and AML. Treatment duration and responses are shown in the figure below. The median time to first response is 1.9 months in MDS patients and 2.2 months in AML patients. By intention-to-treat analysis in all 55 patients, and with a median follow up of 10.5 months, median OS was 11.6 months (95% confidence interval: 9.2 – 14.0 months) with significantly prolonged OS of 12.8 months in responding patients versus 3.9 months in non-responding patients (p < 0.0001). In the subset of 41 MDS/AML patients, median OS was 12.2 months (95% confidence interval: 9.8 – 14.6 months).

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Treatment duration and response in evaluable MDS/AML patients
Data cutoff: July 15, 2019 (n=41)

GRAPHIC

        Treatment with azacitidine is the standard of care for frontline therapy in TP53 mutant MDS and AML, with ORR of 40-45% and a CR rate of 20%. A limited number of peer-reviewed publications have reported the duration of response, or DoR, and PFS in this patient population; from the available public data, DoR is approximately 4-5 months and PFS is approximately 4-8 months. In the 41 evaluable patients in the U.S. trial, ORR was 88% (95% confidence interval: 73 - 95%) and CR rate was 59% (95% confidence interval: 43 - 75%). For the evaluable Phase 1b patients, where the data is mature, DoR was 7.5 months (95% confidence interval: 5.8 - 8.4 months) and PFS was 9.3 months (95% confidence interval: 8.2 - 10.6 months) as of the data cutoff. These data are summarized in the following figure.

Rates and Duration of Response

GRAPHIC


(1)
Data from Sallman et al, 2018 Annual Meeting of the American Society of Hematology, poster 1817; Bally et al, Leukemia Res., 2014; Takahashi et al, Oncotarget, 2016; Kulasekararaj, Br. J. Haematol., 2013; Bejar et al, Blood, 2014; Falconi et al, Leukemia, 2018.

(2)
Duration of response

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        Reported adverse events, or AEs, are mostly low-grade (Grade 1 or 2). Grade 3 or higher AEs are mostly associated with the underlying disease. In the APR-246 monotherapy lead-in phase there were no dose-limiting toxicities, no serious adverse events attributed to APR-246 and all treatment-related AEs were low-grade. The following chart summarizes the AEs reported in more than one patient during the APR-246 monotherapy lead-in phase.

AEs reported in > 1 patient during APR-246 monotherapy lead-in phase (n=12)

Adverse event, n (%)
  Any grade   Grade ³ 3  

Nausea

    5 (42 )   0 (0 )

Peripheral sensory neuropathy

    5 (42 )   0 (0 )

Back pain

    3 (25 )   0 (0 )

Febrile neutropenia

    2 (17 )   2 (17 )

Anemia

    2 (17 )   2 (17 )

Headache

    2 (17 )   0 (0 )

Dizziness

    2 (17 )   0 (0 )

        The most common AEs observed across all cycles of treatment in the trial, as of the cutoff date and regardless of causality, are summarized in the following chart. Only three patients (5%) discontinued treatment due to AE. Serious adverse events, regardless of causality, reported for more than one patient were: febrile neutropenia (27%), lung infection (9%), infections and infestations (5%), respiratory failure (5%), sepsis (5%), vomiting (5%), chest pain (4%), dehydration (4%), intracranial hemorrhage (4%) and multi-organ failure (4%).

Most common reported AEs with APR-246 + azacitidine treatment, regardless of causality (³20%)
Data cutoff: July 15, 2019 (n=55)

Adverse event, n (%)
  Any grade   Grade ³ 3  

Nausea

    35 (65 )   0 (0 )

Vomiting

    24 (44 )   1 (2 )

Fatigue

    23 (42 )   0 (0 )

Constipation

    22 (40 )   0 (0 )

Dizziness

    19 (35 )   1 (2 )

Diarrhea

    19 (35 )   1 (2 )

Febrile neutropenia

    18 (31 )   18 (33 )

Neutropenia

    16 (29 )   16 (29 )

Edema—limbs

    16 (29 )   1 (2 )

Infections and infestations

    16 (29 )   6 (11 )

Dsypnea

    16 (29 )   2 (4 )

Peripheral sensory neuropathy

    15 (27 )   0 (0 )

Leukopenia

    15 (27 )   14 (25 )

Thrombocytopenia

    15 (27 )   13 (24 )

Cough

    15 (27 )   1 (2 )

Headache

    14 (25 )   0 (0 )

Pruritus

    13 (24 )   0 (0 )

Mucositis oral

    12 (22 )   0 (0 )

Fever

    12 (22 )   1 (2 )

Skin and subcutaneous tissue disorders

    12 (22 )   0 (0 )

Tremor

    11 (20 )   1 (2 )

Anorexia

    11 (20 )   0 (0 )

Alanine aminotransferase increased

    11 (20 )   1 (2 )

Lung infection

    11 (20 )   9 (16 )

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        The most common AEs, determined by an investigator to be possibly, probably or definitely related to APR-246 or azacitidine, are summarized in the following chart.

Most common reported AEs with possible, probable or definite relation to APR-246 or azacitidine (³10%)
Data cutoff: July 15, 2019 (n=55)

Adverse event, n (%)
  Any grade   Grade ³ 3  

Nausea

    32 (58 )   0 (0 )

Vomiting

    24 (44 )   1 (2 )

Dizziness

    17 (31 )   1 (2 )

Constipation

    13 (24 )   0 (0 )

Peripheral sensory neuropathy

    12 (22 )   0 (0 )

Leukopenia

    12 (22 )   11 (20 )

Thrombocytopenia

    11 (20 )   9 (16 )

Neutropenia

    10 (18 )   10 (18 )

Fatigue

    8 (15 )   0 (0 )

Tremor

    8 (15 )   0 (0 )

Pruritus

    7 (13 )   0 (0 )

Diarrhea

    6 (11 )   0 (0 )

Anorexia

    6 (11 )   0 (0 )

        Fifty-eight TP53 mutations, representing 49 unique mutations, were identified in the subset of 41 evaluable MDS and AML patients. Consistent with prior published findings, the majority of these were missense mutations (79%) and located in the DNA-binding domain (93%). Other TP53 mutations sequenced in the 41 evaluable MDS and AML patients included insertion-deletion mutations (3%), splice-site mutations (5%), frameshift mutations (5%) and nonsense mutations (7%). The distribution of TP53 mutations by type and breadth of mutations by response are shown in the figure below.

TP53 mutations by type in evaluable MDS/AML patients
Data cutoff: July 15, 2019 (n=41)

GRAPHIC

TP53 mutations by best response in evaluable MDS/AML patients
Data cutoff: July 15, 2019 (n=41)

GRAPHIC

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    The French Phase 1b/2 MDS/AML Trial

        We are supporting an ongoing investigator-initiated single-arm, open-label Phase 1b/2 trial in France by the Groupe Francophone des Myélodysplasies, or GFM, under lead investigator Prof. Pierre Fenaux, to expand the adverse event and efficacy data set in MDS and AML patients treated with the combination of APR-246 and azacitidine. The trial was initiated in September 2018 and reached final enrollment of 53 patients in July 2019. The median age of enrolled patients is 73 years. Thirty-four of 53 patients (64%) had a diagnosis of MDS and 19/53 (36%) with AML. At baseline, 74% of MDS patients were very high risk by IPSS-R. Complex karyotype was found in 89% of enrolled patients.

        The protocol specifies administration of 4500 mg/d APR-246 as a 6-hour intravenous infusion daily for four consecutive days, with administration of 75 mg/m2/d azacitidine by sub-cutaneous injection or intravenously beginning on Day 4 after completion of APR-246 infusion and continuing for 6 additional days. Patients who receive benefit from frontline therapy and undergo allo-HCT are eligible to continue with post-transplant maintenance therapy with APR-246 and azacitidine. As of July 2019, of the 53 patients enrolled, there were 11 MDS patients and 5 AML patients that had at least one serial bone marrow biopsy performed and were evaluable for response in accordance with trial protocol. Responses were achieved in 8/11 (73%) of MDS patients with 55% CR rate, and 4/5 (80%) of AML patients with a 60% CR rate, for a combined 75% ORR and 56% CR rate. As demonstrated in the following table, these data from the French Phase 1b/2 MDS/AML Trial are qualitatively consistent with data from the U.S. Phase 1b/2 MDS/AML Trial.

Comparison of best response in French Phase 1b/2 MDS/AML Trial and U.S. Phase 1b/2 MDS/AML Trial

MDS
  French phase 1b/2
MDS/AML trial
(n=11)
  U.S. phase 1b/2
MDS/AML trial
(n=33)
 

ORR, %

    73     88  

CR, %

    55     61  

mCR + HI, %

    9     21  

mCR, %

    0     3  

HI, %

    9     3  

 

AML
  French phase 1b/2
MDS/AML trial
(n=5)
  U.S. phase 1b/2
MDS/AML trial
(n=8)
 

ORR, %

    80     88  

CR, %

    60     50  

MLFS, %

    20     25  

HI, %

    0     13  

 

Combined MDS + AML
  French phase 1b/2
MDS/AML trial
(n=16)
  U.S. phase 1b/2
MDS/AML trial
(n=41)
 

ORR, %

    75     88  

CR, %

    56     59  

mCR + HI / CRi / CRp, %

    6     17  

mCR / MLFS, %

    6     7  

HI, %

    6     5  

        Serious adverse events, regardless of causality, reported in more than one patient in the French Phase 1b/2 MDS/AML Trial were: Febrile neutropenia (23%), device related infection (9%), sepsis (8%), pneumonia (6%), cerebellar syndrome (4%), lung disorder (4%), lung infection (4%), subdural hematoma (4%), urinary tract infection (4%).

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    The Phase 2 MDS/AML Post-transplant Trial

        There is a significant unmet medical need for more effective therapies for patients with TP53 mutant AML and MDS following allo-HCT given that the one year post-transplant relapse-free survival, or RFS, rate is only 30%. In the second quarter of 2019, we opened enrollment to our Phase 2 MDS/AML Post-Transplant Trial to evaluate the benefit of APR-246 with azacitidine on RFS in TP53 mutant MDS and AML patients who have received allo-HCT. The protocol specifies administration of 3700 mg/d APR-246 as a 6-hour intravenous infusion daily on days 1 through 4, with administration of 35 mg/m2/d azacitidine by sub-cutaneous injection or intravenously on days 1 through 5. Patients may receive a maximum of 12 cycles of maintenance therapy in the Phase 2 MDS/AML Post-Transplant Trial. Target enrollment in the trial is 31 patients and the primary endpoint is 1-year RFS. In addition, we will evaluate the adverse event profile of APR-246 with azacitidine as maintenance treatment post-HCT.

    The Phase 1/2 AML Trials

        We have designed and plan to conduct a Phase 1/2 clinical trial evaluating the adverse event profile and efficacy of treatment with APR-246 and ABT-199/venetoclax, the Bcl-2 inhibitor, with or without azacitidine, in frontline and R/R TP53 mutant AML. Bcl-2 is a pro-survival protein that is frequently expressed at high levels in tumor cells and acts to restrict apoptosis. Inhibition of Bcl-2 protein relieves its anti-apoptotic function, thereby augmenting apoptosis. In preclinical trials, we have observed strong synergy when APR-246 and the Bcl-2 inhibitor are combined in the TP53 mutant AML cell line, KBM3, as shown in the figure below, and believe that this combination may provide meaningful improvements in durable responses for TP53 mutant AML patients with previously untreated and relapsed/refractory AML.

Strong synergy(1) is observed in TP53 mutant cells treated with APR-246 and the Bcl-2 inhibitor

GRAPHIC


(1)
Synergy analyzed using the Highest Single Agent (HSA) method.

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        Under the anticipated trial design, frontline and R/R TP53 mutant AML patients who have received prior HMA therapy will receive treatment with APR-246 and the Bcl-2 inhibitor, and frontline patients who are HMA-naïve will receive treatment with APR-246, Bcl-2 inhibitor and azacitidine. We intend to expand the number of patients in individual arms of the trial, as warranted by adverse event and efficacy data, to enable a path to registration in frontline and R/R AML. We anticipate enrollment of the first patient in the fourth quarter of 2019. The following figure shows the design of the Phase 1/2 AML Trials.

Design of the Phase 1/2 AML Trials

GRAPHIC


(1)
Intensive chemotherapy

(2)
CR with partial hematologic recovery

Clinical development in solid tumors

    Phase 1b/2 Clinical Trial of APR-246 in Platinum-Sensitive Ovarian Cancer, or PiSARRO

        As part of the early development strategy, APR-246 was evaluated in clinical trials in ovarian cancer and this decision was based on the anticipated market size and high prevalence of TP53 mutation of greater than 95% in high-grade serous ovarian cancer, or HGSOC. In March 2014, a Phase 1b trial was initiated as a part of a combined Phase 1b/2 protocol in platinum-sensitive HGSOC to evaluate APR-246 with carboplatin and pegylated liposomal doxorubicin, or PLD. All patients had previously been treated with platinum-based antineoplastic agents and all had accumulation of p53, as assessed by immunohistochemistry, or IHC, as a surrogate marker of mutant p53. Archival samples were available for 29 patients, of which 27 had DNA of sufficient quality for sequencing and all 27 were confirmed to be TP53 mutant.

        The completed Phase 1b part of the trial was conducted as a dose-escalation in 35 platinum-sensitive and partially platinum-sensitive patients. The primary trial objectives of the Phase 1b portion were to assess the adverse event profile of APR-246 with carboplatin and PLD, to determine a recommended Phase 2 dose level, or RP2D, and to evaluate the pharmacokinetics of APR-246 with carboplatin and PLD. Tumor response was a secondary objective.

        The most frequently reported APR-246-related AEs were nausea, dizziness and fatigue, of which most were low-grade. A limited number of APR-246-related grade 3+ AEs were reported, including neutropenia (37%), vomiting (14%), thrombocytopenia (9%), dizziness (6%), anemia (6%), fatigue (3%), headache (3%) and decreased appetite (3%). Serious adverse events, regardless of causality, reported in more than one patient were: device related infection (17%), vomiting (17%), febrile neutropenia (8%), infection (6%), small intestinal obstruction (6%) and thrombocytopenia (6%).

        Although efficacy was not a Phase 1b trial objective, tumor response was evaluated. A 67% ORR was observed in 27 patients who were evaluable for radiological response according to RECIST 1.1,

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including 11% with complete response and 56% with partial response. In addition, an 84% ORR was observed in 25 patients who were evaluable for CA-125 response according to Gynecologic Cancer InterGroup, or GCIG, criteria. Reductions in lesion size and declines in CA-125 are shown in the following figure below. All patients who were evaluable by RECIST 1.1 achieved a best response of stable disease or better, where stable disease indicates lack of objective response but without disease progression. The median time between prior platinum therapy and disease progression prior to enrollment in the trial, known as platinum free interval, or PFI, was 9.4 months, and 40% of patients had received more than one prior line of platinum-based chemotherapy. Two-thirds of patients enrolled in the trial were partially platinum-sensitive, with PFI 6-12 months. The remaining one-third of patients were platinum-sensitive, with PFI greater than 12 months. The median progression-free survival, or PFS, was 10.2 months across all patients and was 10 months and 11.4 months in partially platinum-sensitive and platinum sensitive patients, respectively. The median OS was 24.3 months. This was the first clinical trial of APR-246 with cytotoxic chemotherapy and we believe that the data demonstrated that the agent can be combined with carboplatin and PLD at standard doses.

GRAPHIC

        Data supporting the carboplatin and PLD doublet as a treatment option in platinum-sensitive HGSOC were generated in the CALYPSO trial, a phase 3 clinical trial sponsored by an international consortium of 10 cancer research organizations. The CALYPSO trial enrolled 976 patients, randomized to receive either carboplatin and PLD (48%) or carboplatin and paclitaxel (52%). All patients had received a maximum of two prior lines of chemotherapy; in the carboplatin and PLD arm, 88% had received one prior line and 12% had received two prior lines. The median interval since last chemotherapy, or therapy-free interval, was 15.2 months in the carboplatin and PLD arm, of whom 35% had a therapy-free interval of 6-12 months and 65% had a therapy-free interval in excess of 12 months. The most frequently reported AEs in the carboplatin and PLD arm included neutropenia (80%), nausea (78%), fatigue (78%), anemia (66%), constipation (55%) and vomiting (49%). The most common grade 3+ AEs included neutropenia (35%), thrombocytopenia (16%) and anemia (8%). In the carboplatin and PLD arm PFS was reported as 11.3 months and OS as 30.7 months. Median PFS in the carboplatin and PLD arm was greater than the 9.4 months PFS in the carboplatin and paclitaxel arm (hazard ratio: 0.821, 95% CO, 0.72 – 0.94, P = 0.005). Response rates were not reported for the CALYPSO trial. Whereas the CALYPSO trial enrolled a majority of patients with treatment-free interval exceeding 12 months, our PiSARRO Phase 1b trial enrolled a majority of patients with partially platinum-sensitive disease which is generally recognized as a patient population with inferior treatment outcomes.

        In the third quarter of 2016, enrollment commenced in the Phase 2 portion of the PiSARRO trial and concluded at 211 patients. The Phase 2 part was an open-label, randomized, controlled multi-center trial to assess whether patients with platinum-sensitive recurrent HGSOC would benefit from treatment with APR-246 in combination with carboplatin/PLD chemotherapy regimen. All patients were