Prospectus Supplement

We are offering 9,090,909 shares of our common stock and warrants to purchase up to 6,818,181 shares of our common stock (and the common stock issuable from time to time upon exercise of the offered warrants). The shares of common stock and warrants will be sold in combination, with one warrant to purchase up to 0.75 of a share of common stock accompanying each share of common stock sold. The combined purchase price for each share of common stock and accompanying warrant is $5.50.

Each warrant will have an exercise price of $5.50 per share, will become exercisable on August 2, 2016 and will expire on August 2, 2021. The shares of common stock and accompanying warrants are immediately separable and will be issued separately, but will be purchased together in this offering.

Our common stock is listed on the NASDAQ Global Market under the symbol “ARGS.” The last reported sale price of our common stock on July 27, 2016 on the NASDAQ Global Market was $6.46 per share. There is no established trading market for the warrants and we do not expect a market to develop. We do not intend to list the warrants on the NASDAQ Global Market, any other national securities exchange or any other nationally recognized trading system.

We are an emerging growth company as that term is used in the Jumpstart Our Business Startups Act of 2012 and, as such, have elected to comply with certain reduced public company reporting requirements for this prospectus and future filings. See “Prospectus Supplement Summary—Implications of Being an Emerging Growth Company.”

This investment involves risk. See “Risk Factors” beginning on page S-11 in this Prospectus Supplement.

The above summary of offering proceeds to us does not give effect to any exercise of the warrants being issued in this offering.

Certain of our existing principal stockholders, including Pharmstandard International S.A. and entities affiliated with Forbion, have indicated an interest in purchasing an aggregate of up to approximately $21.5 million in shares of our common stock and accompanying warrants in this offering at the public offering price. However, because indications of interest are not binding agreements or commitments to purchase, these stockholders may determine to purchase fewer shares and warrants than they indicate an interest in purchasing or not to purchase any shares and warrants in this offering. It is also possible that these stockholders could indicate an interest in purchasing more shares of our common stock and warrants. In addition, the underwriters could determine to sell fewer shares and warrants to any of these stockholders than the stockholders indicate an interest in purchasing or not to sell any shares and warrants to these stockholders. The underwriters will not receive any underwriting discount on the sale of shares of common stock and accompanying warrants to these existing stockholders.

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

The underwriters expect to deliver the shares of our common stock and accompanying warrants on or about August 2, 2016.

This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference herein. The second part, the accompanying prospectus, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement and the information contained in the accompanying prospectus or any document incorporated by reference therein filed prior to the date of this prospectus supplement, you should rely on the information in this prospectus supplement; provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

We have not authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus supplement, the accompanying prospectus or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus supplement and the accompanying prospectus do not constitute an offer to sell, or a solicitation of an offer to purchase, the securities offered by this prospectus supplement and the accompanying prospectus in any jurisdiction to or from any person to whom or from whom it is unlawful to make such offer or solicitation of an offer in such jurisdiction. The information contained in this prospectus supplement or the accompanying prospectus, or incorporated by reference herein or therein is accurate only as of the respective dates thereof, regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or of any sale of our common stock and accompanying warrants to purchase shares of our common stock. It is important for you to read and consider all information contained in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, in making your investment decision. You should also read and consider the information in the documents to which we have referred you in the sections entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference” in this prospectus supplement and in the accompanying prospectus.

We are offering to sell, and seeking offers to buy, shares of our common stock and warrants to purchase common stock only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the accompanying prospectus and the offering of the common stock and the accompanying warrants to purchase shares of the common stock in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement and the accompanying prospectus must inform themselves about, and observe any restrictions relating to, the offering of the common stock and the accompanying warrants to purchase shares of the common stock and the distribution of this prospectus supplement and the accompanying prospectus outside the United States. This prospectus supplement and the accompanying prospectus do not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement and the accompanying prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

Unless otherwise stated, all references in this prospectus supplement and the accompanying prospectus to “we,” “us,” “our,” “Argos,” “the Company” and similar designations refer, collectively, to Argos Therapeutics, Inc., a Delaware corporation, and its consolidated subsidiary.

This prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein include “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. All statements, other than statements of historical facts, included in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans, objectives of management and expected market growth are forward-looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements include, among other things, statements about:

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have included important factors in the cautionary statements included in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein, particularly in the “Risk Factors” section of this prospectus supplement and in our “critical accounting estimates” described in Part II, Item 7 “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Estimates” of our most recent Annual Report on Form 10-K, which is incorporated by reference in this prospectus supplement, that could cause actual results or events to differ materially from the forward-looking statements that we make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments that we may make.

You should read this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein completely and with the understanding that our actual future results may be materially different from what we expect. We do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information contained elsewhere in this prospectus supplement and the accompanying prospectus and in the documents we incorporate by reference. This summary does not contain all of the information you should consider before investing in our securities. You should read this entire prospectus supplement and the accompanying prospectus carefully, especially the risks discussed under “Risk Factors” beginning on page S-11 of this prospectus supplement, along with our consolidated financial statements and notes to those consolidated financial statements and the other information incorporated by reference in this prospectus supplement and the accompanying prospectus, before making an investment decision.

Corporate Overview

We are an immuno-oncology company focused on the development and commercialization of individualized immunotherapies for the treatment of cancer and infectious diseases based on our proprietary technology platform called Arcelis.

Our most advanced product candidate is AGS-003, which we are developing for the treatment of metastatic renal cell carcinoma, or mRCC, and other cancers. We are currently conducting a pivotal Phase 3 clinical trial of AGS-003 plus sunitinib or another targeted therapy for the treatment of newly diagnosed mRCC under a special protocol assessment, or SPA, with the Food and Drug Administration, or FDA. We refer to this trial as the ADAPT trial. We opened the ADAPT trial for enrollment in January 2013, dosed the first patient in May 2013 and completed enrollment of the trial in July 2015. Based upon the actual rate of enrollment and projected event rate as defined in the protocol, we anticipate having a sufficient number of events to permit the primary analysis and assessment of overall survival to occur in the first half of 2017. In June 2016, the independent data monitoring committee, or IDMC, for the ADAPT trial recommended that the ADAPT trial continue based on results of the IDMC’s scheduled interim data review. We expect that the next IDMC meeting will occur in connection with the Genitourinary Cancers Symposium in February 2017. We are also supporting investigator-initiated Phase 2 trials in patients with early stage RCC and non-small cell lung cancer and plan to support investigator-initiated trials of AGS-003 in muscle invasive bladder cancer and in combination with checkpoint inhibitors in mRCC.

We are developing AGS-004, our second most advanced Arcelis-based product candidate, for the treatment of HIV. We have completed Phase 1 and Phase 2 trials funded by government grants and a Phase 2b trial that was funded in full by the National Institutes of Health, or NIH, and the National Institute of Allergy and Infectious Diseases, or NIAID, under a $39.8 million agreement. We are currently supporting an ongoing investigator-initiated Phase 2 clinical trial of AGS-004 in adult HIV patients evaluating the use of AGS-004 in combination with a latency reversing drug for HIV eradication, and plan to support a second investigator-initiated Phase 2 clinical trial of AGS-004 evaluating AGS-004 for long-term viral control in pediatric patients.

Our Arcelis Platform

Our proprietary Arcelis technology platform utilizes biological components from a patient’s own cancer cells or virus to generate individualized immunotherapies. These immunotherapies employ specialized white blood cells called dendritic cells to activate an immune response specific to the patient’s own disease. We believe our Arcelis-based immunotherapies are applicable to a wide range of cancers and infectious diseases and have the following attributes that we consider critical to a successful immunotherapy:

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target a patient’s disease-specific antigens, including mutated antigens, or neoantigens, to elicit a potent immune response that is specific to the patient’s own disease;

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overcome the immune suppression that exists in cancer and infectious disease patients;

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induce memory T-cells, a specialized type of immune cell that is known to correlate with improved clinical outcomes for cancer and HIV patients;

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have minimal toxicity; and

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can be produced using a centralized manufacturing process at a cost that will be comparable to biologics.

We believe that our immunotherapies combine the advantages of other approaches to immunotherapy, including antigen-based approaches and pathway-based approaches such as checkpoint inhibition, while addressing limitations that they present, and also provide the opportunity for the development of new combination treatment regimens.

Our Development Programs

The following table summarizes our development programs for AGS-003 and AGS-004.


Product Candidate	Primary Indication	Status
AGS-003	mRCC	• Ongoing ADAPT trial; enrollment completed in July 2015; data expected in the first half of 2017

		• Planned investigator-initiated Phase 2 clinical trial in combination with PD-1 and PD-L1 checkpoint inhibitors, expected to open for enrollment by the end of 2016

	Early stage RCC (neoadjuvant)	• Ongoing investigator-initiated Phase 2 clinical trial; initial data expected by the end of 2016

	Advanced solid tumors	• Ongoing investigator-initiated Phase 2 clinical trial in non-small cell lung cancer

		• Planned investigator-initiated Phase 2 clinical trial in muscle invasive bladder cancer, expected to open for enrollment in the second half of 2016

AGS-004	HIV	• Ongoing second stage of investigator-initiated Phase 2 clinical trial for HIV eradication

		• Planned investigator-initiated Phase 2 clinical trial for long-term viral control in pediatric patients, expected to open for enrollment in 2017

We hold all commercial rights to AGS-003 and AGS-004 in all geographies other than rights to AGS-003 in Russia and the other states comprising the Commonwealth of Independent States, which we exclusively licensed to Pharmstandard International S.A., or Pharmstandard, rights to AGS-003 for the treatment of mRCC in South Korea, which we exclusively licensed to Green Cross Corp., or Green Cross, and rights to AGS-003 in China, Hong Kong, Taiwan and Macau, which we exclusively licensed to Lummy (Hong Kong) Co. Ltd., or Lummy HK. We have granted to MEDcell Co., Ltd., a wholly-owned subsidiary of Medinet Co. Ltd., hereinafter referred to together as “Medinet,” an exclusive license to manufacture in Japan AGS-003 for the treatment of mRCC.

AGS-003

We are developing AGS-003 for the treatment of mRCC and other cancers. We are currently conducting the ADAPT trial of AGS-003 plus sunitinib / targeted therapy for the treatment of newly diagnosed mRCC, versus

sunitinib/targeted therapy alone, in a protocol developed under an SPA with the FDA. We opened the ADAPT trial for enrollment in January 2013 and dosed the first patient in May 2013. In July 2015 we completed enrollment in the trial, enrolling 462 patients with the goal of generating 290 events for the primary endpoint of overall survival. We enrolled these patients at 127 clinical sites in North America, Europe and Israel. Under the trial protocol, these patients were randomized between the AGS-003 plus sunitinib/targeted therapy combination arm and the sunitinib/targeted therapy alone control arm on a two-to-one basis. In June 2016, the IDMC for the ADAPT trial recommended that the ADAPT trial continue based on results of the IDMC’s scheduled interim data review. We expect that the next IDMC meeting will occur in connection with the Genitourinary Cancers Symposium in February 2017. Based on internal projections, we believe that we have reached more than half of the targeted number of events for the ADAPT trial’s overall survival primary endpoint. Based upon the actual rate of enrollment and the projected event rate as defined in the protocol, we anticipate having a sufficient number of events to permit the primary analysis and assessment of overall survival to occur in the first half of 2017.

In addition, in mRCC we plan to support an investigator-initiated clinical trial of AGS-003 in combination with PD-1 and PD-L1 checkpoint inhibitors that we expect will open for enrollment by the end of 2016.

We are also supporting an ongoing investigator-initiated Phase 2 clinical trial designed to evaluate neoadjuvant treatment with AGS-003 in patients with early stage, localized RCC prior to nephrectomy. This trial was opened for enrollment in late 2014 and four patients were enrolled as of March 15, 2016. We expect that a total of 10 patients will be enrolled in this trial. This trial provides the opportunity to observe the impact of AGS-003 on the immune response in both the peripheral blood and in the primary tumor that is removed after AGS-003 treatment, the latter as evidenced by the presence of tumor infiltrating lymphocytes in the tumor.

We believe that AGS-003 may be capable of treating a wide range of cancers and are planning to evaluate AGS-003 in clinical trials in additional cancer indications. We are supporting an investigator-initiated Phase 2 clinical trial of AGS-003 in patients with non-small cell lung cancer, or NSCLC, that was opened for enrollment in the first quarter of 2016. In the trial, the safety, efficacy and immunologic effects of AGS-003 when combined with platinum-based chemotherapy and radiation will be evaluated in approximately 20 NSCLC patients. In the trial, AGS-003 will be administered either concurrently with chemotherapy and with or without radiation or sequentially with chemotherapy and with or without radiation, according to the patient’s assigned treatment arm. We are conducting this trial in NSCLC patients because NSCLC is a tumor type reported to have a high number of mutated targets for the immune system, which could make it more susceptible to AGS-003’s mechanism of action. We also believe platinum-based chemotherapy has immunomodulatory effects by downregulating immunosuppressive regulatory T-cells which may lead to an additive or synergistic effect with AGS-003.

We also plan to support an additional investigator-initiated Phase 2 clinical trial of AGS-003 in muscle invasive bladder cancer, which we expect to open for enrollment in the second half of 2016. The trial has two phases: a pre-treatment phase and a treatment phase. In the pre-treatment phase, tumor tissue will be obtained via a transurethral resection of the bladder tumor, which will then be used to extract RNA for the manufacture of AGS-003. In the treatment phase, AGS-003 will be given before tumor resection and combined with standard-of-care cytotoxic chemotherapy, consisting of cisplatin and gemcitabine. Booster doses of AGS-003 will continue after tumor resection. As with the neoadjuvant RCC trial, we expect that the trial will provide us with the opportunity to observe the impact of AGS-003 on the immune response in both the peripheral blood and the primary tumor, the latter as evidenced by the presence of tumor infiltrating lymphocytes in the tumor.

AGS-004

We are developing AGS-004 for the treatment of HIV and are focusing this program on the use of AGS-004 in combination with other therapies for the eradication of HIV. We believe that by combining AGS-004 with

therapies that are being developed to expose the virus in latently infected cells to the immune system, we can potentially eradicate the virus. The current standard-of-care, antiretroviral drug therapy, or ART, can reduce levels of HIV in a patient’s blood, increase the patient’s life expectancy and improve the patient’s quality of life. However, ART cannot eliminate the virus, which persists in latently infected cells, where it remains undetectable by the immune system and can lead to disease recurrence. In addition, ART requires daily, life-long treatment which can have significant side effects and impact patients’ quality of life.

We are supporting an investigator-initiated Phase 2 clinical trial of AGS-004 in adult HIV patients to evaluate the use of AGS-004 in combination with the latency reversing drug vorinostat for the eradication of HIV at the University of North Carolina. Vorinostat is marketed under the name Zolinza by Merck & Co. Inc. for the treatment of cutaneous T-cell lymphoma. This trial is being conducted in two stages. Stage 1 of this trial, which was designed to study immune response kinetics to AGS-004 in patients on continuous ART, has been completed. Data from Stage 1 were used to better define the optimal dosing strategy for the combination of AGS-004 and vorinostat in the ongoing Stage 2 phase of this trial. We expect that up to 12 adult HIV patients will be studied in Stage 2. These patients will receive alternating courses of AGS-004 and vorinostat, and will continue ART throughout the study. In July 2016, the first patient in Stage 2 was dosed. The patient clinical costs for the first stage of this trial were funded by Collaboratory of AIDS Researchers for Eradication, or CARE. The second stage of the trial is being funded by a federal research grant from the Division of AIDS of the National Institute of Allergy and Infectious Diseases at NIH.

We also plan to explore the use of AGS-004 monotherapy to provide long-term control of HIV viral load in otherwise immunologically healthy patients and eliminate their need for ART. Accordingly, we plan to support an investigator-initiated Phase 2 clinical trial of AGS-004 monotherapy in pediatric patients infected with HIV who have otherwise healthy immune systems and have been treated with ART since birth or shortly thereafter and, as a result, are lacking the antiviral memory T-cells to combat the virus. The commencement of this trial is subject to approval of the protocol by the principal investigator(s), institutional review boards, the IMPAACT Network leadership and the FDA and to the agreement by the NIH to fund the trial costs not related to AGS-004 manufacturing. Assuming the supportive data and the necessary approvals are obtained, we expect this trial to initiate in 2017.

Manufacturing

We currently have manufacturing suites in our facility located at our corporate headquarters in Durham, North Carolina. We manufacture our Arcelis-based product candidates for research and development purposes and for clinical trials at this facility. In August 2014, we entered into a lease agreement with the developer, TKC LXXII, LLC, or TKC. Under the lease agreement, we agreed to lease certain land and an approximately 125,000 square-foot building to be constructed in Durham County, North Carolina, which we refer to as Centerpoint. We intended this facility to house our corporate headquarters and commercial manufacturing. The shell of the new facility was constructed on a build-to-suit basis in accordance with agreed upon specifications and plans and was completed in June 2015. However, the build-out and equipping of the interior of the facility have been suspended as we explore potential financing arrangements.

Under the lease agreement, we had an option to purchase the property for an amount estimated at $7.4 million. In February 2015, we exercised this purchase option and entered into a Purchase and Sale Agreement with TKC. The purchase price to be paid by us is $7.4 million plus the amount of any additional costs incurred by TKC as a result of changes requested by us, for which we have paid $1.7 million as of March 31, 2016, and the amount of any improvement allowances advanced to us by TKC prior to the closing. Under the terms of the Purchase and Sale Agreement, we have until September 23, 2016 to consummate the purchase of the property. If we purchase the property, the lease agreement will terminate upon the closing.

We are actively exploring financing arrangements in connection with the planned Centerpoint facility. Under the arrangements we are discussing with a real estate investment firm, we would expect to transfer our right to purchase Centerpoint to, and concurrently enter into a long-term lease with, the real estate investment firm. Under the terms of the proposed lease, both the real estate investment firm and we would provide funding for the build-out and equipping of approximately 50,000 square feet of life science manufacturing and laboratory space and 25,000 square feet of office space. We expect that our share of the costs associated with the build-out and equipping of the facility would be approximately $11 million, in addition to the approximately $11 million we have committed to the project to date, and that the real estate investment firm’s share of these costs would be approximately $28 million. We would plan to fund our share of these costs with proceeds from this offering. We further expect that the lease would have a 20-year term, with five successive five-year renewal options, and an initial annual rental rate of $3.1 million, with a two percent escalation each year. In the event that the real estate investment firm contributes to the further build-out and equipping of the facility beyond the initial 75,000 square feet, the annual rental rate would be adjusted according to agreed upon terms. The real estate investment firm would be the sole owner of Centerpoint. We would retain certain rights of first negotiation and rights of first refusal in the event that the real estate investment firm decides to sell the property, and would receive a portion of the proceeds from any sale or significant refinancing of the facility above a threshold amount.

We are also exploring alternatives for the commercial supply of our products, including the leasing, build-out and equipping of an existing facility in Durham County, North Carolina for commercial manufacture. Under this alternative, we would enter into an agreement with a contract manufacturing organization that would initially provide for the leasing of the facility. Under this alternative, we would provide initial funding for the build-out and equipping of manufacturing space, with an additional payment due to the contract manufacturing organization upon biologic license application, or BLA, approval. Also under this alternative, we would be solely responsible for all manufacturing operations through the end of the first full year of commercialization efforts. Following the first full year of commercialization efforts, we would have the option to terminate for a fee or to continue the arrangement and transition the manufacturing operations from us to the contract manufacturing organization. The contract manufacturing organization would be the sole owner of the facility, and we would only pay rent during the period in which we would be solely responsible for manufacturing operations.

We expect that we will enter into arrangements for the commercial manufacture of our products in the second half of 2016. Under either alternative, we expect that it would take approximately nine to 12 months to complete the build-out and equipping of a commercial manufacturing facility and that such arrangements would likely involve material obligations. However, we have not entered into any binding arrangement with any party with respect to the lease, build-out and equipping of a manufacturing facility, and the contemplated arrangements described above have not been finalized and are subject to change. There can be no assurance that we will enter into arrangements on the terms contemplated, on a timely basis or at all.

We plan to establish manual and automated manufacturing processes in the commercial manufacturing facility. However, we have determined to delay the implementation of our automated manufacturing process until after commercialization of AGS-003, and thus plan to seek marketing approval of AGS-003 and, if approved, to initially commercially supply AGS-003 using our manual manufacturing process. Prior to implementing commercial manufacturing of AGS-003, we will be required to demonstrate that the commercial manufacturing facility is constructed and operated in accordance with current good manufacturing practice. We will also be required to show the comparability between AGS-003 that we produce using the manual processes in our current facility and AGS-003 produced using the manual process in the new facility.

Intellectual Property

We own or exclusively license 10 U.S. patents and six U.S. patent applications, as well as approximately 60 foreign counterparts, covering our Arcelis technology platform and Arcelis-based product candidates.

We use our Arcelis technology platform to generate individualized mRNA-loaded dendritic cell immunotherapies. The process of obtaining a disease sample and dendritic cells from a patient, using those materials to manufacture an individualized drug product and shipping the drug product to the clinical site for use in the treatment of the patient involves many important steps. These steps include:

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amplifying mRNA from a disease sample obtained from the patient;

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differentiating dendritic cell precursors (monocytes) isolated from the patient into immature dendritic cells;

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maturing the immature dendritic cells in culture and loading the mature dendritic cells with the amplified mRNA and CD40L protein; and

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formulating the matured, loaded dendritic cells in the patient’s plasma with cryoprotectants to protect the cells in the resulting drug product when the drug product is frozen and thawed.

We have sought to protect these steps or the equipment related to carrying out one or more of these steps through patents or trade secrets. We have also sought to protect the resultant drug product through patents.

We believe that all of the above aspects of our Arcelis technology platform are required to successfully produce our Arcelis-based product candidates and are covered by a combination of our patents, patent applications, trade secrets and know-how. The U.S. patents expire between 2021 and 2029, and the U.S. patent applications, if issued, would expire between 2025 and 2029, the counterpart patents in Europe and Japan expire between 2017 and 2027, and the counterpart patent applications in Europe and Japan, if issued, would expire between 2025 and 2027.

In addition, if the use of Arcelis-based products for the treatment of mRCC and HIV are approved by the FDA, then, depending upon factors such as the timing and duration of FDA review and the timing and conditions of FDA approval, as well as factors such as patent claim scope, some of our issued U.S. patents (or patents that may issue from our pending U.S. patent applications) may be eligible for limited patent term extension under the Hatch-Waxman Act.

Risks Associated with Our Business

Our business is subject to a number of risks of which you should be aware before making an investment decision. These risks are discussed more fully in the “Risk Factors” section of this prospectus supplement immediately following this prospectus supplement summary. These risks include the following:

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We currently have no commercial products and have not received regulatory approval for any of our products.

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We will need to obtain significant financing in addition to the net proceeds of this offering prior to the commercialization of AGS-003, including to complete the planned leasing, build-out and equipping of a commercial manufacturing facility to complete required activities in preparation for the submission of a biologic license application, or BLA, for AGS-003 and to fund other pre-commercialization activities. If we are unable to obtain additional financing when needed, in the required amounts or at all, we may not be able to complete the planned leasing, build-out and equipping of the commercial facility, to complete the required activities in preparation for the submission of the BLA or conduct other required pre-commercialization activities or may be delayed in doing so.

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If our ongoing pivotal Phase 3 ADAPT clinical trial of AGS-003 in combination with sunitinib/targeted therapy fails to demonstrate safety and efficacy to the satisfaction of the FDA, we would incur additional costs and experience delays in completing, or ultimately may be unable to complete, the development and commercialization of AGS-003.

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To date, we have not completed a randomized clinical trial of AGS-003 against a placebo or a comparator therapy, including sunitinib as a monotherapy. While we believe comparisons of results of earlier clinical

trials of AGS-003 to results of clinical trials of sunitinib conducted by other parties and analyses of data from the International Metastatic Renal Cell Carcinoma Database Consortium can assist in evaluating the potential efficacy of AGS-003, results from two different trials or between a trial and an analysis of a treatment database often cannot be reliably compared and may not be predictive of the outcome of our ongoing pivotal Phase 3 clinical trial of AGS-003 in combination with sunitinib or another targeted therapy.

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Only one individualized immunotherapy has been approved by the FDA to date. Our use of our novel Arcelis technology to create our individualized immunotherapies may raise development issues that we may not have anticipated or be able to resolve and may raise regulatory issues that could delay or prevent approval of our individualized immunotherapies.

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We are focusing our program for AGS-004 on its use in combination with other therapies for the eradication of HIV. To date, no drugs have been approved by the FDA for HIV eradication. As a result, we cannot be certain as to the clinical trials that we will need to conduct or the regulatory requirements that we will need to satisfy in order to obtain marketing approval of AGS-004 to eradicate HIV.

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We do not have experience in manufacturing Arcelis-based products on a commercial scale. If we are unable to successfully manufacture these products on a commercial scale, our business may be materially harmed.

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We plan to seek government or other third party funding for the continued development of AGS-004 and to collaborate with third parties for the development and commercialization of AGS-004. If we are unable to obtain such funding or establish such collaborations, we may not be able to develop or commercialize AGS-004.

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We have incurred significant losses since our inception and, as of March 31, 2016, we had an accumulated deficit of $291.8 million. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.

Company Information

We were incorporated under the laws of the State of Delaware on May 8, 1997. Our principal executive offices are located at 4233 Technology Drive, Durham, North Carolina 27704, and our telephone number is (919) 287-6300. Our website address is www.argostherapeutics.com. The information contained on, or that can be accessed through, our website is not a part of this prospectus supplement. We have included our website address in this prospectus supplement solely as an inactive textual reference.

The trademarks, trade names and service marks appearing in this prospectus supplement are the property of their respective owners.

Implications of Being an Emerging Growth Company

As a company with less than $1 billion in 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. As an emerging growth company, we may take advantage of specified reduced disclosure and other requirements that are otherwise applicable generally to public companies. These provisions include:

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reduced disclosure about our executive compensation arrangements;

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no non-binding advisory votes on executive compensation or golden parachute arrangements; and

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exemption from the auditor attestation requirement in the assessment of our internal controls over financial reporting.

We may take advantage of these exemptions for up to five years following our initial public offering in February 2014 or such earlier time that we are no longer an emerging growth company. We would cease to be an

emerging growth company if we have more than $1 billion in annual revenue, we have more than $700 million in market value of our stock held by non-affiliates or we issue more than $1 billion of non-convertible debt over a three-year period. We may choose to take advantage of some, but not all, of the available exemptions. We have taken advantage of certain reduced reporting burdens in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein. Accordingly, the information contained herein and therein may be different than the information you receive from other public companies in which you hold stock.

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. This allows an emerging growth company to delay the adoption of certain accounting standards 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, are subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

THE OFFERING


Common Stock offered by Argos in this offering		9,090,909 shares.

Warrants offered by Argos in this offering		Warrants to purchase up to 6,818,181 shares of our common stock. Each warrant will have an exercise price of $5.50 per share, will be exercisable upon issuance and will expire on August 2, 2021. This prospectus supplement also relates to the offering of the shares of common stock issuable upon exercise of these warrants.

Common Stock to be outstanding after this offering		41,122,361 shares.

Use of Proceeds		We plan to use the net proceeds from this offering, together with our existing cash, cash equivalents and short-term investments, to fund our pivotal Phase 3 ADAPT trial of AGS-003, the ongoing and planned investigator-initiated Phase 2 clinical trials of AGS-003, our share of the expected costs of the leasing, build-out and equipping of a commercial manufacturing facility and activities in preparation for the submission of a biologic license application, or BLA, to the FDA for AGS-003, and for working capital and other general corporate purposes. See “Use of Proceeds.”

Risk Factors		You should read the “Risk Factors” section of this prospectus supplement beginning on page S-11 for a discussion of factors to consider before investing in our securities.

NASDAQ Global Market symbol		“ARGS.” We do not intend to list the warrants on The NASDAQ Global Market, any other national securities exchange or any other nationally recognized trading system.

The number of shares of our common stock to be outstanding after this offering is based on the 32,031,452 shares of our common stock outstanding as of June 30, 2016, excludes the shares of common stock issuable upon exercise of the warrants being offered by us in this offering and also excludes the following:

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82,780 shares of common stock issuable upon the exercise of warrants outstanding as of June 30, 2016, at an exercise price of $9.06 per share;

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6,848,328 shares of common stock issuable upon the exercise of warrants outstanding as of June 30, 2016, at an exercise price of $5.35 per share;

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one share of common stock issuable upon the exercise of a warrant outstanding as of June 30, 2016, at an exercise price of $23,894.34 per share;

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4,422,086 shares of common stock issuable upon the exercise of stock options outstanding as of June 30, 2016, at a weighted average exercise price of $6.08 per share; and

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777,939 shares of common stock available for future issuance under our equity compensation plans as of June 30, 2016.

Except as otherwise noted, this prospectus supplement reflects and assumes no exercise of outstanding stock options or warrants described above.

Certain preliminary financial data included in this prospectus supplement, including our cash, cash equivalents and short-term investments as of June 30, 2016, has been prepared by, and is the responsibility of our management. PricewaterhouseCoopers LLP, our independent registered public accounting firm, has not audited, reviewed, compiled or performed any procedures with respect to the preliminary financial data. Accordingly, PricewaterhouseCoopers LLP does not express an opinion or any other form of assurance with respect thereto.

Investing in our securities involves a high degree of risk. Before you decide to invest in our securities, you should carefully consider the risks and uncertainties described below together with all other information contained in this prospectus supplement, the accompanying prospectus and in our filings with the SEC that we have incorporated by reference in this prospectus supplement and the accompanying prospectus. If any of the following risks actually occurs, our business, financial condition or results of operations could be adversely affected, which, in turn, could have a negative impact on the price of our common stock. 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 the Development and Regulatory Approval of Our Product Candidates

We depend heavily on the success of our two product candidates, AGS-003 and AGS-004, both of which are still in clinical development. Clinical trials of our product candidates may not be successful. If we are unable to commercialize our product candidates or experience significant delays in doing so, our business will be materially harmed.

We currently have no products approved for sale. We have invested a significant portion of our efforts and financial resources in the development of AGS-003 for the treatment of metastatic renal cell carcinoma, or mRCC, and other cancers and AGS-004 for the treatment of HIV. Our ability to generate product revenues, which we do not expect will occur for at least the next several years, if ever, will depend heavily on the successful development and eventual commercialization of these product candidates. The success of these product candidates will depend on several factors, including the following:

If we do not achieve one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to successfully commercialize our product candidates, which would materially harm our business.

If clinical trials of our product candidates, such as our ADAPT trial of AGS-003, fail to demonstrate safety and efficacy to the satisfaction of the FDA or similar regulatory authorities outside the United States or do not otherwise produce positive results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our product candidates.

Before obtaining regulatory approval for the sale of our product candidates, we must conduct extensive clinical trials to demonstrate the safety and efficacy of our product candidates in humans. 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 of our clinical trials can occur at any stage of testing. 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. For instance, despite observing positive results in earlier clinical trials of AGS-004, we failed to achieve the primary endpoint of our Phase 2b clinical trial of AGS-004. Similarly, recommendations of the independent data monitoring committee that the ADAPT trial should be continued based on results of the committee’s interim data analyses of interim trial results may not be indicative as to the final results of the trial. 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 products.

In particular, to date, we have not completed a randomized clinical trial of AGS-003 against a placebo or a comparator therapy. While we believe comparisons to results from other reported clinical trials or from analyses of data from the International Metastatic Renal Cell Carcinoma Database Consortium, or the Consortium, can assist in evaluating the potential efficacy of our AGS-003 product candidate, there are many factors that affect the outcome for patients, some of which are not apparent in published reports. As a result, results from two different trials or between a trial and an analysis of a treatment database often cannot be reliably compared. Our ADAPT trial of AGS-003 is intended to compare directly the combination of AGS-003 and sunitinib or another targeted therapy to treatment with sunitinib or another targeted therapy monotherapy. Based on the design of the trial, the data from the trial will need to demonstrate an increase in median overall survival of approximately six months for the AGS-003 plus sunitinib / targeted therapy arm as compared to the sunitinib / targeted therapy monotherapy control arm in order to show statistical significance and achieve the primary endpoint of the trial. We will need to show this statistically significant benefit of the combined therapy as compared to treatment with the sunitinib / targeted therapy monotherapy as part of a biologics license application, or BLA, submission for approval of AGS-003. However, demonstration of statistical significance and achievement of the primary endpoint of the trial do not assure approval by the FDA or similar regulatory authorities outside the United States.

Patients in our ADAPT trial who receive treatment with sunitinib / targeted therapy monotherapy may not have results similar to patients studied in other clinical trials of sunitinib or to patients in the Consortium database who were treated with sunitinib or other targeted therapies. If the patients in our ADAPT trial who receive sunitinib / targeted therapy alone have results which are better than the results that occurred in those other clinical trials or the results described in the Consortium database, we may not demonstrate a sufficient clinical benefit from AGS-003 in combination with sunitinib and other targeted therapies to allow the FDA to approve AGS-003 for marketing. In addition, only 21 patients received the combination of AGS-003 and sunitinib in our single arm Phase 2 clinical trial. If the patients in our ADAPT trial who receive the combination of AGS-003 and sunitinib / targeted therapy have results which are worse than the results that occurred in our Phase 2 clinical trial, we may not demonstrate a sufficient benefit from the combination therapy to allow the FDA to approve AGS-003 for marketing.

For drug and biological products, the FDA typically requires the successful completion of two adequate and well-controlled clinical trials to support marketing approval because a conclusion based on two such trials will be more reliable than a conclusion based on a single trial. In the case of AGS-003, which is intended for a life-threatening disease, we intend to seek approval based upon the results of a single pivotal Phase 3 clinical trial, our ADAPT trial. The FDA reviewed our plans to conduct our ADAPT trial under its special protocol assessment, or SPA, process. In February 2013, the FDA advised us in a letter that it had completed its review of our plans under the SPA process. The FDA also informed us that in order for a single trial to support approval of an indication, the trial must be well conducted, and the results of the trial must be internally consistent, clinically meaningful and statistically very persuasive. If the results for the primary endpoint are not robust, are subject to confounding factors, or are not adequately supported by other trial endpoints, the FDA may refuse to approve our BLA based upon a single clinical trial. In addition, because only 21 patients received the combination of AGS-003 and sunitinib in our Phase 2 clinical trial, and as a result, we did not have enough evaluable patients to

perform the statistical analysis to determine whether the primary endpoint of complete response rate was achieved in that trial, we expect that the data from our Phase 2 clinical trial will have only a limited impact on the FDA’s ultimate assessment of efficacy of AGS-003. Thus, there can be no guarantee that the FDA will not require additional pivotal clinical trials as a condition for approving AGS-003 or as a post-approval requirement.

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 only modestly positive or if there are safety concerns, we may:

If we experience any of a number of possible unforeseen events in connection with our clinical trials, potential marketing or commercialization of our product candidates could be delayed or prevented.

We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive regulatory approval or commercialize our product candidates. For example, in September 2011, the FDA placed the original protocol for our ADAPT trial of AGS-003 in combination with sunitinib on partial clinical hold due to unresolved questions regarding the planned measurement of the secretion of the cytokine interleukin-12, or IL-12, as part of the specifications for the release of AGS-003. We subsequently reached an agreement with the FDA regarding the IL-12 release specifications and the FDA lifted the partial clinical hold.

Unforeseen events that could delay or prevent our ability to receive regulatory approval or commercialize our product candidates include:

In addition, the patients recruited for clinical trials of our product candidates may have a disease profile or other characteristics that are different than we expect and different than the clinical trials were designed for, which could adversely impact the results of the clinical trials. For instance, our Phase 2 combination therapy clinical trial of AGS-003 in combination with sunitinib was originally designed to enroll patients with favorable disease risk profiles and intermediate disease risk profiles and with a primary endpoint of complete response rate. However, the actual trial population consisted entirely of patients with intermediate disease risk profiles and poor disease risk profiles. This is a population for which published research has shown that sunitinib alone, as well as other of the targeted therapies for mRCC, rarely if ever produce complete responses in mRCC, and in our Phase 2 clinical trial in this population the combination therapy of AGS-003 and sunitinib did not show a complete response rate that met the endpoint of the trial.

Our product development costs will also increase if we experience delays in testing or obtaining marketing approvals. We do not know whether any clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. For example, in response to our submission of an investigational new drug application, or IND, for AGS-004, the FDA raised safety concerns regarding the analytical treatment interruption contemplated by our protocol for our Phase 2 clinical trial of AGS-004, and required a one year safety follow-up after the final dose for each patient. This resulted in the need for an amendment to the trial protocol and a four month delay prior to initiating the Phase 2 clinical trial in the United States. In addition to additional costs, 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 products to market before we do and impair our ability to commercialize our product candidates and may harm our business and results of operations.

The FDA has reviewed the protocol for our ADAPT trial of AGS-003 in combination with sunitinib / targeted therapy under the SPA process. However, agreement by the FDA with the protocol under the SPA process does not guarantee that the trial will be successful or that, if successful, AGS-003 will receive marketing approval.

The FDA has reviewed, under the SPA process, the protocol for our ADAPT trial of AGS-003 in combination with sunitinib / targeted therapy. The SPA process is designed to facilitate the FDA’s review and approval of drug and biological products by allowing the FDA to evaluate the proposed design and size of Phase 3 clinical trials that are intended to form the primary basis for determining a drug candidate’s efficacy. In February 2012, we received a letter from the FDA advising us that the FDA had completed its review of our protocol for the ADAPT trial under the SPA process. In the letter, the FDA stated that it had determined that the protocol sufficiently addressed the trial’s objectives and that the trial was adequately designed to provide the necessary data to support a submission for marketing approval.

An SPA does not guarantee that AGS-003 will receive marketing approval. The FDA may raise issues related to safety, trial conduct, bias, deviation from the protocol, statistical power, patient completion rates, changes in scientific or medical parameters or internal inconsistencies in the data prior to making its final decision. The FDA may also seek the guidance of an outside advisory committee prior to making its final decision. In addition, the combination of AGS-003 and sunitinib may not achieve the primary endpoint of the trial. Even if the primary endpoint in our ADAPT trial is achieved, AGS-003 may not be approved. Many companies which have been granted SPAs have ultimately failed to obtain final approval to market their products.

In its February 2012 letter, the FDA informed us that in order for a single trial to support approval of an indication, the trial must be well conducted, and the results of the trial must be internally consistent, clinically meaningful and statistically very persuasive. If the results for the primary endpoint are not robust, are subject to confounding factors, or are not adequately supported by other trial endpoints, the FDA may refuse to approve our BLA based upon a single clinical trial. There can be no guarantee that the FDA will not require additional pivotal clinical trials before, or as a condition for, approving AGS-003.

If we experience delays or difficulties in the enrollment of patients in our clinical trials, our receipt of necessary regulatory 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 similar regulatory authorities outside the United States. Our competitors may have ongoing clinical trials for product candidates that could be competitive with our product candidates, and patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ product candidates. For example, during the Phase 1/2 monotherapy clinical trial of AGS-003 that we conducted, our ability to enroll patients in the trial was adversely affected by the FDA’s approval of sorafenib and sunitinib, because patients did not want to receive, and physicians were reluctant to administer, AGS-003 as an experimental monotherapy once new therapies that showed efficacy in clinical trials were introduced to the market and became widely available.

The actual amount of time for full enrollment of our clinical trials could be longer than planned. Enrollment delays in any of our clinical trials may result in increased development costs for our product candidates, which would cause the value of the company to decline and limit our ability to obtain additional financing. Our inability to enroll a sufficient number of patients for any of our other clinical trials would result in significant delays or may require us to abandon one or more clinical trials altogether.

We are developing AGS-004 for use in combination with latency reversing drugs to eradicate HIV. If latency reversing drugs are not successfully developed for HIV on a timely basis or at all, we will be unable to develop AGS-004 for this use or will be delayed in doing so. In addition, because there are currently no products approved for HIV eradication, we cannot be certain of the clinical trials that we will need to conduct or the regulatory requirements that we will need to satisfy in order to obtain marketing approval of AGS-004 for this purpose.

We are focusing our development program for AGS-004 on the use of AGS-004 in combination with latency reversing drugs, including vorinostat, to eradicate HIV. We plan to rely on these latency reversing drugs because we recognize that the ultimate objective of virus eradication is unlikely to be achieved with immunotherapy alone because the immune system is not able to recognize the HIV virus in latently infected cells with a low level or lack of expression of HIV antigens.

Several companies and academic groups are evaluating latency reversing drugs that can potentially activate latently infected cells to increase viral antigen expression and make the cells vulnerable to elimination by the immune system. We are not a party to any arrangements with these companies or academic groups. If these companies or academic groups determine not to develop latency reversing drugs for this purpose because the drugs do not sufficiently increase viral antigen expression or have unacceptable toxicities, or these companies or academic groups otherwise determine to collaborate with other developers of immunotherapies on a combination therapy for complete virus eradication, we will not be able to complete our AGS-004 development program. In addition, if these companies or academic groups do not proceed with such development on a timely basis, our AGS-004 program correspondingly would be delayed.

A number of the latency reversing drugs being evaluated for use in HIV patients are currently approved in the United States and elsewhere for use in the treatment of specified cancer indications. For instance, vorinostat is approved for cutaneous T-cell lymphoma. If these drugs are not approved by the FDA or equivalent foreign regulatory authorities for use in HIV, the FDA and these other regulatory authorities may not approve AGS-004 without the latency reversing drug having received marketing approval for HIV. If the FDA and these other regulatory authorities approve AGS-004 without the approval of the latency reversing drug for HIV, the use of AGS-004 in combination with the latency reversing drug for virus eradication would require sales of the latency reversing drug for off-label use. In such event, the success of the combination of AGS-004 and the latency reversing drug would be subject to the willingness of physicians, patients, healthcare payors and others in the medical community to use the latency reversing drug for off-label use and of government authorities and third party payors to pay for the combination therapy. In addition, we would be limited in our ability to market the combination for its intended use if the latency reversing drug were to be used off-label.

Currently, there are no products approved for the eradication of HIV. As a result, we cannot be certain as to the clinical trials we will need to conduct or the regulatory requirements that we will need to satisfy in order to obtain marketing approval of AGS-004 for the eradication of HIV.

If serious adverse or inappropriate side effects are identified during the development of our product candidates, we may need to abandon or limit our development of some of our product candidates.

All of our product candidates are still in preclinical or clinical development and their risk of failure is high. It is impossible to predict when or if any of our product candidates will prove effective or safe in humans or will receive regulatory approval. If our product candidates are associated with undesirable side effects or have characteristics that are unexpected, we may need to abandon their development or limit development 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. In addition, such effects or characteristics could cause an institutional review board or regulatory authorities to interrupt, delay or halt clinical trials of one or more of our product candidates, require us to conduct additional clinical trials or other tests or studies, and could result in a more restrictive label, or the delay or denial of marketing approval by the FDA or comparable foreign regulatory authorities.

Our Arcelis-based product candidates are immunotherapies that are based on a novel technology utilizing a patient’s own tissue. This may raise development issues that we may not have anticipated or be able to resolve, regulatory issues that could delay or prevent approval or personnel issues that may prevent us from further developing and commercializing our product candidates.

AGS-003 and AGS-004 are based on our novel Arcelis technology platform. In the course of developing this platform and these product candidates, we have encountered difficulties in the development process. For example, we terminated the development of MB-002, the predecessor to AGS-003, when the results from the initial clinical trial of MB-002 indicated that the product candidate only corrected defects in the production of one of two critical cytokines required for effective immune response. There can be no assurance that additional development problems will not arise in the future which we have not anticipated or may not be able to resolve or which may cause significant delays in development.

In addition, regulatory approval of novel product candidates such as our Arcelis-based product candidates manufactured using novel manufacturing processes such as ours can be more expensive and take longer than for other, more well-known or extensively studied pharmaceutical or biopharmaceutical products, due to our and regulatory agencies’ lack of experience with them. The FDA has only approved one individualized immunotherapy product to date. This lack of experience may lengthen the regulatory review process, require us to conduct additional studies or clinical trials, increase our development costs, lead to changes in regulatory positions and interpretations, delay or prevent approval and commercialization of these product candidates or lead to significant post-approval limitations or restrictions.

The novel nature of our product candidates also means that fewer people are trained in or experienced with product candidates of this type, which may make it difficult to find, hire and retain capable personnel for research, development and manufacturing positions.

Development of our individualized Arcelis-based product candidates is subject to significant uncertainty because each product candidate is derived from source material that is inherently variable. This variability could reduce the effectiveness of our Arcelis-based product candidates, delay any FDA approval of our Arcelis-based product candidates, cause us to change our manufacturing methods and adversely affect the commercial success of any approved Arcelis-based products.

The disease samples from the patients to be treated with our Arcelis-based products vary from patient to patient. This inherent variability may adversely affect our ability to manufacture our products because each tumor or virus sample that we receive and process will yield a different product. As a result, we may not be able to consistently produce a product for every patient and we may not be able to treat all patients effectively. Such inconsistency could delay FDA or other regulatory approval of our Arcelis-based product candidates or if approved, adversely affect market acceptance and use of our Arcelis-based products. If we have to change our manufacturing methods to address any inconsistency, we may have to perform additional clinical trials, which would delay FDA or other regulatory approval of our Arcelis-based product candidates and increase the costs of development of our Arcelis-based product candidates.

The inherent variability of the disease samples from the patients to be treated with our Arcelis-based products may further adversely affect our ability to manufacture our products because variability in the source material for our product candidates, such as tumor cells or viruses, may cause variability in the composition of other cells in our product candidates. Such variability in composition or purity could adversely affect our ability to establish acceptable release specifications and the development and regulatory approval processes for our product candidates may be delayed, which would increase the costs of development of our Arcelis-based product candidates.

If we are not able to obtain, or if there are delays in obtaining, required regulatory approvals, we will not be able to commercialize our product candidates, and our ability to generate revenue will be materially impaired.

Failure to obtain regulatory approval for either of our product candidates will prevent us from commercializing the product candidate. We have not received regulatory approval to market any of our product candidates in any jurisdiction. We have only limited experience in filing and supporting the applications necessary to gain regulatory approvals and expect to rely on third party contract research organizations to assist us in this process. Securing FDA approval requires the submission of extensive preclinical and clinical data and supporting information to the FDA for each therapeutic indication to establish the product candidate’s safety and efficacy. Securing FDA approval also requires the submission of information about the product manufacturing process to, and inspection of manufacturing facilities by, the FDA. Our product candidates may not be effective, may be only moderately effective or may prove to have undesirable or unintended side effects, toxicities or other characteristics that may preclude our obtaining regulatory approval or prevent or limit commercial use.

The process of obtaining regulatory approvals, both in the United States and abroad, is expensive, may take many years if additional clinical trials are required, 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. To date, the FDA has only approved one individualized immunotherapy product. Changes in clinical guidelines or regulatory approval policies during the development period, changes in or the enactment of additional statutes or regulations, or changes in regulatory review for each submitted product application, may cause delays in the approval or rejection of an application. The FDA has 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, clinical or other studies. In addition, varying interpretations of the data obtained from preclinical and clinical testing could delay, limit or prevent regulatory approval of a product candidate. Any regulatory approval we ultimately obtain may be limited or subject to restrictions or post-approval commitments that render the approved product not commercially viable.

If we experience delays in obtaining approval or if we fail to obtain approval of our product candidates, the commercial prospects for our product candidates may be harmed and our ability to generate revenues will be materially impaired.

Failure to obtain regulatory approval in international jurisdictions would prevent our product candidates from being marketed abroad.

We are a party to arrangements with third parties, and intend to enter into additional arrangements with third parties, under which they would market our products outside the United States. In order to market and sell our products in the European Union and many other jurisdictions, we or such third parties must obtain separate regulatory 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 regulatory approval process outside the United States generally includes all of the risks associated with obtaining FDA approval. In addition, in many countries outside the United States, it is required that the product be approved for reimbursement before the product can be approved for sale in that country. We or these third parties may not obtain approvals from regulatory authorities outside 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 the United States does not ensure approval by regulatory authorities in other countries or jurisdictions or by the FDA. We may not be able to file for regulatory approvals and may not receive necessary approvals to commercialize our products in any market.

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

If a product is intended for the treatment of a serious or life-threatening condition and the product demonstrates the potential to address an unmet need for this condition, the treatment sponsor may apply for FDA fast track designation. In April 2012, the FDA notified us that we obtained fast track designation for AGS-003 for the treatment of mRCC. Fast track designation does not ensure that we will experience a faster development, regulatory review or approval process compared to conventional FDA procedures. Additionally, the FDA may withdraw fast track designation if it believes that the designation is no longer supported by data from our clinical development program.

We have incurred significant losses since our inception. We expect to incur losses for at least the next several years and may never achieve or maintain profitability.

Since inception, we have incurred significant operating losses. Our net loss was $53.3 million for the year ended December 31, 2014, $74.8 million for the year ended December 31, 2015 and $12.8 million for the three months ended March 31, 2016. As of March 31, 2016, we had an accumulated deficit of $291.8 million.

To date, we have financed our operations primarily through public offerings of common stock, private placements of common stock, preferred stock and warrants, convertible debt financings, debt from financial institutions, government contracts, government and other third party grants and license and collaboration agreements. We have devoted substantially all of our efforts to research and development, including clinical trials. We have not completed development of any product candidates. 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:

To become and remain profitable, we must develop and eventually commercialize a product or products with significant market potential. This development and commercialization will require us to be successful in a range of challenging activities, including successfully completing preclinical testing and clinical trials of our product candidates, obtaining regulatory approval for these product candidates, building out and equipping a commercial manufacturing facility and manufacturing, marketing and selling those products for which we may obtain regulatory approval. We are only in the preliminary stages of some of these activities. We may never succeed in these activities and may never generate revenues that are significant or large enough to achieve profitability.

Even 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 the company and could impair our ability to raise capital, expand our business, maintain our research and development efforts or continue our operations. A decline in the value of our company could also cause you to lose all or part of your investment.

We will need substantial additional funding beyond the proceeds of this offering. If we are unable to raise capital when needed, we would be forced to delay, reduce, terminate or eliminate our product development programs, including our plans to build out and equip a leased commercial manufacturing facility, or our commercialization efforts and to take other actions to reduce our operating expenses.

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue our ADAPT trial of AGS-003 for the treatment of mRCC, continue to support ongoing investigator-initiated clinical trials of AGS-003 and AGS-004, support planned investigator-initiated clinical trials of AGS-003 and AGS-004, initiate and conduct additional clinical trials of AGS-003 and AGS-004 for the treatment of cancers and HIV,

seek regulatory approval for our product candidates and lease, build out and equip a commercial manufacturing facility. In addition, if we obtain regulatory approval of any of our product candidates, we expect to incur significant commercialization expenses for product sales, marketing, manufacturing and distribution. Furthermore, we expect to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding beyond the proceeds of this offering in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce, terminate or eliminate our product development programs, our plans to lease, build out and equip a commercial manufacturing facility or our commercialization efforts and to take other actions to reduce our operating expenses.

As of March 31, 2016, we had cash, cash equivalents and short-term investments of $13.8 million and working capital of $0.9 million. As of June 30, 2016, we had cash, cash equivalents and short-term investments of $34.8 million. Based on our current operating plan, we expect that the net proceeds from this offering, together with our existing cash, cash equivalents and short-term investments as of June 30, 2016, will enable us to fund our operating expenses through the third quarter of 2017. We expect that our available funds following this offering will be sufficient to fund our operations until such time as there are a sufficient number of events to permit the primary analysis and assessment of overall survival in the ADAPT trial and our share of the expected costs of leasing, building-out and equipping a commercial manufacturing facility assuming that we enter into the contemplated arrangements related to the facility. We expect that these funds will not, however, be sufficient to enable us to complete required activities in preparation for the submission of a BLA to the FDA for AGS-003, to commercially launch AGS-003 or to complete the build-out and equipping of a commercial manufacturing facility without entering into such arrangements related to the facility. These expectations are based on our current operating plan under which we implemented measures to reduce our operating expenses, including, among other measures, reductions in spending for activities in preparation for submission of a BLA and a workforce reduction action plan designed to streamline operations and reduce our operating expenses. Under our plan, we also intend to seek to refinance our existing venture loan facility with Horizon Technology Finance Corporation, or Horizon, and Fortress Credit Co LLC, or Fortress under which we are required to begin making principal payments in October 2016. If we are unable to refinance this facility and are required to begin making principal payments as currently required, we expect that the net proceeds from this offering, together with our existing cash, cash equivalents and short-term investments as of June 30, 2016, would only fund our operating expenses through the second quarter of 2017. We also intend to seek to enter into collaborations for the development, marketing and distribution of AGS-003 outside North America and of our non-oncology product candidates, including AGS-004. If we are unable to refinance our venture loan facility or enter into any such collaborations, we may be required to implement additional measures to materially reduce our operating expenses, which could adversely affect our business and operations. It is also possible that our available funds will not enable us to reach a sufficient number of events to permit the primary analysis and assessment of overall survival in the ADAPT trial because the actual costs and timing of clinical trials are difficult to predict and are subject to substantial risks and delays.

We will also need to obtain significant financing to lease, build out and equip a commercial manufacturing facility. Based upon a proposed arrangement for the Centerpoint commercial manufacturing facility, we estimate that our share of the costs associated with the leasing, build-out and equipping of the Centerpoint commercial manufacturing facility, will be approximately $11 million, in addition to the $11 million we have already committed to this project. We are also actively exploring other financing arrangements using a contract manufacturing organization that may provide for a reduced investment by us. We expect to enter into arrangements for a commercial manufacturing facility in the second half of 2016 and that such arrangements will likely involve material obligations. If we are unable to enter into such arrangements on the anticipated terms, on a timely basis or at all, we may not be able to complete the planned leasing, build-out and equipping of a commercial facility, or may be delayed in doing so, which in either case would delay the commercialization of AGS-003.

Conducting preclinical testing 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 regulatory approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of products that we do not expect to be commercially available for several years, if at all. Accordingly, we will need to continue to rely on additional financing to achieve our business objectives. Additional financing may not be available to us on acceptable terms, or at all.

Our independent registered public accounting firm included an explanatory paragraph relating to our ability to continue as a going concern in its report on our audited financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2015.

Our report from our independent registered public accounting firm for the year ended December 31, 2015 includes an explanatory paragraph stating that our losses from operations and required additional funding to finance our operations raise substantial doubt about our ability to continue as a going concern. If we are unable to obtain sufficient funding, our business, prospects, financial condition and results of operations will be materially

and adversely affected and we may be unable to continue as a going concern. If we are unable to continue as a going concern, we may have to liquidate our assets and may receive less than the value at which those assets are carried on our audited financial statements, and it is likely that investors will lose all or a part of their investment. Even if we successfully complete and receive the net proceeds from this offering, we may still seek additional financing to fund our business activities in the future. If we do and there remains substantial doubt about our ability to continue as a going concern, investors or other financing sources may be unwilling to provide additional funding to us on commercially reasonable terms or at all.

Raising additional capital may cause dilution to our existing stockholders, restrict our operations or require us to relinquish rights to our technologies or product candidates.

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through a combination of equity offerings, debt financings, government contracts, government and other third party grants or other third party funding, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements. We will require substantial funding beyond the proceeds of this offering to complete the planned lease, build-out and equipping of a facility for the commercial manufacture of products based on our Arcelis platform, complete required activities in preparation for the submission of a BLA for AGS-003, fund our commercialization efforts and fund our other operating expenses and other activities. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect your rights as a stockholder.

Debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends.

We currently intend to collaborate with third parties for the manufacturing, development or commercialization of AGS-003 outside of North America. We plan to seek government or other third party funding for the continued development of AGS-004 and to collaborate with third parties for the development and commercialization of AGS-004. If we raise additional funds through government or other third party funding, marketing and distribution arrangements or other collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to us. If the loan from Medinet becomes due and we do not repay it, we have agreed to grant Medinet a non-exclusive, royalty-bearing license to make and sell Arcelis products in Japan for the treatment of cancer.

Our ability to use our net operating loss carry-forwards and tax credit carryforwards may be limited.

The utilization of the net operating loss and tax credit carryforwards may be subject to limitation under the rules regarding a change in stock ownership as determined by the Internal Revenue Code, and state and foreign tax laws. Section 382 of the Internal Revenue Code of 1986, as amended, imposes annual limitations on the utilization of net operating loss carryforwards, other tax carryforwards, and certain built-in losses upon an ownership change as defined under that section. In general terms, an ownership change may result from transactions that increase the aggregate ownership of certain of our stockholders by more than 50 percentage points over a three year testing period. If we have undergone a Section 382 ownership change, an annual limitation would be imposed on certain of our tax attributes, including NOL and capital loss carryforwards, and certain other losses, credits, deductions or tax basis. As of March 31, 2016, we have not completed a formal study to determine whether there are 382 limitations that apply. However, we believe that by engaging in the financing transactions in which we have engaged, we may have triggered an “ownership change” limitation. We may also experience ownership changes in the future as a result of subsequent shifts in our stock ownership. As a result, if we earn net taxable income, our ability to use our pre-change net operating loss carry-forwards and other tax credit carryforwards to offset U.S. federal taxable income may be subject to limitations, which potentially could result in increased future tax liability to us.

We have no history of commercializing pharmaceutical products, which may make it difficult to evaluate the prospects for our future viability.

Our operations to date have been limited to financing and staffing our company, developing our technology and product candidates and establishing collaborations. We have not yet demonstrated an ability to successfully complete a pivotal clinical trial, compile an acceptable regulatory submission, obtain marketing approvals, manufacture a commercial scale product or conduct sales and marketing activities necessary for successful product commercialization. Consequently, predictions about our future success or viability may not be as accurate as they could be if we had a history of successfully developing and commercializing pharmaceutical products.

In addition, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors. We will need to transition at some point from a company with research and development focus to a company capable of supporting commercial activities. We may not be successful in such a transition.

Even if AGS-003 or AGS-004 receives regulatory approval, it may fail to achieve the degree of market acceptance by physicians, patients, healthcare payors and others in the medical community necessary for commercial success.

We have never commercialized a product candidate. Even if AGS-003 or AGS-004 receives marketing approval, it may nonetheless fail to gain sufficient market acceptance by physicians, patients, healthcare payors and others in the medical community. Gaining market acceptance for our Arcelis-based products may be particularly difficult as, to date, the FDA has only approved one individualized immunotherapy and our Arcelis-based products are based on a novel technology. If these products do not achieve an adequate level of acceptance, we may not generate significant product revenues 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:

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

Clinical trials of our product candidates are conducted in carefully defined subsets of patients who have agreed to enter into clinical trials. Consequently, it is possible that our clinical trials may indicate an apparent positive

effect of a product candidate that is greater than the actual positive effect, if any, in a broader patient population or alternatively fail to identify undesirable side effects. If, following approval of a product candidate, we, or others, discover that the product is less effective than previously believed or causes undesirable side effects that were not previously identified, any of the following adverse events could occur:

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

If 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, marketing or distribution of pharmaceutical products. To achieve commercial success for any approved product, we must either develop a sales and marketing organization or outsource these functions to third parties. We plan to market and sell AGS-003 in North America independently and to enter into collaborations or other arrangements with third parties for the distribution or marketing of AGS-003 in the rest of the world. We plan to enter into collaborations or other arrangements with third parties for the distribution or marketing of AGS-004 and any of our other product candidates should such candidates receive marketing approval.

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 product launch. 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 products on our own include:

If we enter into arrangements with third parties to perform sales, marketing and distribution services, our product revenues or the profitability of these product revenues to us are likely to be lower than if we were to market and sell any products 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 doing 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 products 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.

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

The development and commercialization of new drug products is highly competitive. We face competition with respect to our current product candidates, and will face competition with respect to any products that we may seek to develop or commercialize in the future, from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide. There are a number of large pharmaceutical and biotechnology companies that currently market and sell products or are pursuing the development of products for the treatment of the disease indications for which we are developing our product candidates. Potential competitors also include academic institutions, government agencies and other public and private research organizations that conduct research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and commercialization.

Some of these competitive products and therapies are based on scientific approaches that are the same as or similar to our approach, and others are based on entirely different approaches. Many marketed therapies for the indications that we are currently pursuing, or indications that we may in the future seek to address using our Arcelis platform, are widely accepted by physicians, patients and payors, which may make it difficult for us to replace them with any products that we successfully develop and are permitted to market.

The FDA has approved several targeted therapies as monotherapies for mRCC, including Nexavar (sorafenib), marketed by Bayer Healthcare Pharmaceuticals, Inc. and Onyx Pharmaceuticals, Inc.; Sutent (sunitinib) and Inlyta (axitinib), marketed by Pfizer, Inc.; Avastin (bevacizumab), marketed by Genentech, Inc., a member of the Roche Group; Votrient (pazopanib) and Afinitor (everolimus), marketed by Novartis Pharmaceuticals Corporation; Torisel (temsirolimus), marketed by Pfizer; and most recently, Opdivo (nivolumab) for second-line RCC, marketed by Bristol-Myers Squibb. In addition, we estimate that there are numerous therapies for mRCC in clinical development by many public and private biotechnology and pharmaceutical companies targeting numerous different cancer types and stages. A number of these are in late stage development. Opdivo (nivolumab) plus Yervoy (ipilimumab) in combination for first-line mRCC is being developed by Bristol-Myers Squibb and is currently being compared in a Phase 3 trial to sunitinib. Cometriq (cabozantinib) is being developed by Exelixis has recently reported positive results from its Phase 3 trial and is expected to receive FDA approval for second-line mRCC in 2016. In addition, if a standalone therapy for mRCC were developed that demonstrated improved efficacy over currently marketed first-line therapies with a favorable safety profile and without the need for combination therapy, such a therapy might pose a significant competitive threat to AGS-003.

We are currently conducting our ADAPT trial of AGS-003 plus sunitinib / targeted therapy. We elected to study AGS-003 in clinical trials in combination with sunitinib due in part to sunitinib being the current standard-of-care for first-line treatment of mRCC. Although we do not expect to seek FDA approval of AGS-003 solely in combination with sunitinib and have provided that, under the protocol for the ADAPT trial, investigators may discontinue sunitinib due to disease progression or toxicity and initiate second-line treatment with other approved, compatible therapies, if we obtain approval by the FDA, such FDA approval may be limited to the

combination of AGS-003 and sunitinib. In such event, the commercial success of AGS-003 would be linked to the commercial success of sunitinib. As a result, if sunitinib ceases to be the standard-of-care for first-line treatment of mRCC or another event occurs that adversely affects sales of sunitinib, the commercial success of AGS-003 may be adversely affected.

There are also numerous FDA-approved treatments for HIV, primarily antiretroviral therapies marketed by large pharmaceutical companies. Generic competition has developed in this market as patent exclusivity periods for older drugs have expired, with more than 15 generic drugs currently on the market. The presence of these generic drugs is resulting in price pressure in the HIV therapeutics market and could affect the pricing of AGS-004. Currently, there are no approved therapies for the eradication of HIV. We expect that major pharmaceutical companies that currently market antiretroviral therapy products or other companies that are developing HIV product candidates may seek to develop products for the eradication of HIV.

Our competitors may develop products that are more effective, safer, more convenient or less costly than any that we are developing or that would render our product candidates obsolete or non-competitive. Our competitors may also obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours.

Many of our competitors have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and marketing approved products than we do. Mergers and acquisitions in the pharmaceutical, biotechnology and device industries may result in even more resources being concentrated among a smaller number of our competitors. Smaller and other early stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These third parties compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

Even if we are able to commercialize any product candidates, the products may become subject to unfavorable pricing regulations, third party reimbursement practices or healthcare reform initiatives, which would harm our business.

The regulations that govern marketing approvals, pricing and reimbursement for new drug products vary widely from country to country. In the United States, recently passed legislation may significantly change the approval requirements in ways that could involve additional costs and cause delays in obtaining approvals. 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 or product licensing 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 regulatory 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 regulatory approval.

Our ability to commercialize any products successfully also will depend in part on the extent to which reimbursement for these products and related treatments will be available from government health administration authorities, private health insurers and other organizations. 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 U.S. healthcare industry 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, third party payors are requiring that drug companies provide them with predetermined discounts from list prices and are challenging the prices

charged for medical products. We cannot be sure that reimbursement will be available for any product that we commercialize and, if reimbursement is available, the level of reimbursement. Reimbursement may impact the demand for, or the price of, any product candidate for which we obtain marketing approval. Obtaining reimbursement for our products may be particularly difficult because of the higher prices often associated with drugs administered under the supervision of a physician. 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 similar regulatory authorities outside the United States. Moreover, eligibility for reimbursement does not imply that any drug will be paid for 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, and may be incorporated into existing payments for other services. 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 policies. Our inability to promptly obtain coverage and profitable payment rates from both government-funded and private payors for any approved products that we develop could have a material adverse effect on our operating results, our ability to raise capital needed to commercialize products and our overall financial condition.

Product liability lawsuits against us could cause us to incur substantial liabilities and to limit commercialization of any products that we may develop.

We face an inherent risk of product liability exposure related to the testing of our product candidates in human clinical trials and will face an even greater risk if we commercially sell any products that we may develop. These risks may be even greater with respect to our Arcelis-based products which are manufactured using a novel technology. None of our product candidates has been widely used over an extended period of time, and therefore our safety data are limited. We derive the raw materials for manufacturing of our Arcelis-based product candidates from human cell sources, and therefore the manufacturing process and handling requirements are extensive and stringent, which increases the risk of quality failures and subsequent product liability claims.

If we cannot successfully defend ourselves against claims that our product candidates or products caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

We currently hold $10.0 million in product liability insurance coverage, which may not be adequate to cover all liabilities that we may incur. We will need to increase our insurance coverage when we begin

commercializing 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.

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 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 products 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 products.

We have based our research and development efforts on our Arcelis platform. Notwithstanding our large investment to date and anticipated future expenditures in our Arcelis platform, we have not yet developed, and may never successfully develop, any marketed drugs using this approach. As a result of pursuing the development of product candidates using our Arcelis platform, we may fail to develop product candidates or address indications based on other scientific approaches that may offer greater commercial potential or for which there is a greater likelihood of success.

Our long-term business plan is to develop Arcelis-based products for the treatment of various cancers and infectious diseases. We may not be successful in our efforts to identify or discover additional product candidates that may be manufactured using our Arcelis platform. Research programs to identify new product candidates require substantial technical, financial and human resources. These research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development.

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 royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

Our reliance on government funding adds uncertainty to our research and commercialization efforts and may impose requirements that increase the costs of commercialization and production of our government-funded product candidates.

Our current development of AGS-004 for HIV is primarily funded by the NIH. We are depending upon further government funding for continued development of AGS-004. However, increased pressure on governmental budgets may reduce the availability of government funding for programs such as AGS-004. In addition, contracts and grants from the U.S. government and its agencies include provisions that give the government substantial rights and remedies, many of which are not typically found in commercial contracts, including provisions that allow the government to:

Government agreements normally contain additional terms and conditions that may increase our costs of doing business, reduce our profits, and expose us to liability for failure to comply with these terms and conditions. These include, for example:

We expect to depend on collaborations with third parties for the development and commercialization of our product candidates. If those collaborations are not successful, we may not be able to capitalize on the market potential of these product candidates.

We currently intend to commercialize AGS-003 independently in North America. We intend to collaborate with other third parties to manufacture, develop or commercialize AGS-003 outside North America. We have entered into an exclusive license agreement with Pharmstandard International S.A., or Pharmstandard, for the development and commercialization of AGS-003 in Russia and the other states comprising the Commonwealth of Independent States and an exclusive license agreement with Green Cross Corp., or Green Cross, for the development and commercialization of AGS-003 for the treatment of mRCC in South Korea and an exclusive license agreement with Lummy (Hong Kong) Co. Ltd., or Lummy HK, for the development, manufacture and commercialization of AGS-003 in China, Hong Kong, Taiwan and Macau. We have also entered into a license agreement with Medinet under which we granted Medinet an exclusive license to manufacture in Japan AGS-003 for the purpose of development and commercialization for the treatment of mRCC. We also plan to seek government or other third party funding for continued development of AGS-004 and to collaborate with third parties to develop and commercialize AGS-004. Our likely collaborators for any development, distribution, marketing, licensing or broader collaboration arrangements include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies and biotechnology companies.

Under our existing arrangements we have limited control, and under any additional arrangements we may enter into with third parties we will likely have limited control, over the amount and timing of resources that our collaborators dedicate to the development 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.

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

Collaboration agreements may not lead to development or commercialization of product candidates in the most efficient manner, or at all. In addition, there have been a significant number of recent business combinations among large pharmaceutical companies that have resulted in a reduced number of potential future collaborators. If a present or future collaborator of ours were to be involved in a business combination, the continued pursuit and emphasis on our product development or commercialization program could be delayed, diminished or terminated.

If we are not able to establish additional collaborations, we may have to alter our development and commercialization plans.

Our drug development programs and the potential commercialization of our product candidates will require substantial additional cash to fund expenses. For some of our product candidates, we intend to collaborate with pharmaceutical and biotechnology companies for the development and commercialization of those product candidates. For example, we have entered into license agreements with third parties to develop, manufacture and/or commercialize AGS-003 in Russia and the other states comprising the Commonwealth of Independent States,

South Korea, Japan, China, Hong Kong, Taiwan and Macau, and we intend to collaborate with other third parties to develop and commercialize AGS-003 in other parts of the world and to collaborate with third parties to develop and commercialize AGS-004.

We face significant competition in seeking appropriate collaborators. Whether we reach a definitive agreement for a collaboration will depend, among other things, upon our assessment of the collaborator’s resources and expertise, the terms and conditions of the proposed collaboration, and the proposed collaborator’s evaluation of a number of factors. Those factors may include the design or results of clinical trials, the likelihood of approval by the FDA or similar regulatory authorities outside the United States, the potential market for the subject product candidate, the costs and complexities of manufacturing and delivering such product candidate to patients, the potential of competing products, the existence of uncertainty with respect to our ownership of technology, which can exist if there is a challenge to such ownership without regard to the merits of the challenge and industry and market conditions generally. The collaborator may also consider alternative product candidates or technologies for similar indications that may be available to collaborate on and whether such a collaboration could be more attractive than the one with us for our product candidate. We may also be restricted under existing license agreements from entering into agreements on certain terms with potential collaborators. Collaborations are complex and time-consuming to negotiate and document. We may not be able to negotiate collaborations on a timely basis, on acceptable terms, or at all.

If we are not able to obtain such funding or enter into collaborations for our product candidate, we may have to curtail the development of such product candidate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to increase our expenditures to fund development or commercialization activities on our own, we may need to obtain additional capital, which may not be available to us on acceptable terms or at all. If we do not have sufficient funds, we may not be able to further develop these product candidates or bring these product candidates to market and generate product revenue.

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

We do not independently conduct clinical trials of our product candidates. We rely on third parties, such as contract research organizations, clinical data management organizations, medical institutions and clinical investigators, to perform this function. Our reliance on these third parties for clinical development activities reduces our control over these activities but does not relieve us of our oversight responsibilities as sponsor of the trial. We remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial. Moreover, the FDA and other regulatory authorities require us to comply with standards, commonly referred to as Good Clinical Practice, 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. We also are required to register 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, regulatory approvals for our product candidates and will not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates.

For instance, in December 2015 we received a notice from Health Canada that one of the sites at which we are conducting our Phase 3 ADAPT trial in Canada had been found to be non-compliant with Good Clinical Practice in Canada and that if the issues raised in the notice were not corrected, Health Canada could suspend our

authorization to conduct the ADAPT trial at all sites in Canada. We submitted a response to Health Canada and subsequently received a Completion of Response notice from Health Canada stating that our corrective actions were satisfactory and that the matter was officially closed.

We also rely on other third parties to store and distribute product supplies for our clinical trials. Any performance failure on the part of our existing or future distributors could delay clinical development or regulatory approval of our product candidates or commercialization of our products, producing additional losses and depriving us of potential product revenue.

We plan to build out a facility to manufacture our Arcelis-based products on a commercial scale. We do not have experience in manufacturing Arcelis-based products on a commercial scale. If, due to our lack of manufacturing experience, we cannot manufacture our Arcelis-based products on a commercial scale successfully or manufacture sufficient product to meet our expected commercial requirements, our business may be materially harmed.

We currently have manufacturing suites in our facility located at our corporate headquarters in Durham, North Carolina. We manufacture our Arcelis-based product candidates for research and development purposes and for clinical trials at this facility. In August 2014, we entered into a lease agreement with the developer, TKC LXXII, LLC, or TKC. Under the lease agreement, we agreed to lease certain land and an approximately 125,000 square-foot building to be constructed in Durham County, North Carolina, which we refer to as Centerpoint. We intended this facility to house our corporate headquarters and commercial manufacturing. The shell of the new facility was constructed on a build-to-suit basis in accordance with agreed upon specifications and plans and was completed in June 2015. However, the build-out and equipping of the interior have been suspended as we explore potential financing arrangements.

Under the lease agreement, we had an option to purchase the property. In February 2015, we exercised this purchase option and entered into a Purchase and Sale Agreement with TKC. The purchase price to be paid by us is $7.4 million plus the amount of any additional costs incurred by TKC as a result of changes requested by us, for which we have paid $1.7 million as of March 31, 2016, and the amount of any improvement allowances advanced to us by TKC prior to the closing. Under the terms of the Purchase and Sale Agreement, we have until September 23, 2016 to consummate the purchase of the property. If we purchase the property, upon the closing, the lease agreement will terminate.

We are also exploring alternatives for the commercial supply of our products, including the leasing, build-out and equipping of an existing facility in Durham County, North Carolina for commercial manufacture. Under this alternative, we would enter into an agreement with a contract manufacturing organization that would initially provide for the leasing of the facility. Under this alternative, we would provide initial funding for the build-out and equipping of manufacturing space, with an additional payment due to the contract manufacturing organization upon BLA approval. Also under this alternative, we would be solely responsible for all manufacturing operations through the end of the first full year of commercialization efforts. Following the first full year of commercialization efforts, we would have the option to terminate for a fee or to continue the arrangement and transition the manufacturing operations from us to the contract manufacturing organization. The contract manufacturing organization would be the sole owner of the facility, and we would only pay rent during the period in which we would be solely responsible for manufacturing operations.

We have not entered into any binding arrangement with any party with respect to the lease, build-out and equipping of a manufacturing facility, and the contemplated arrangements described above have not been finalized and are subject to change. There can be no assurance that we will enter into arrangements on the terms contemplated, on a timely basis or at all.

We plan to initiate commercial manufacturing using our current manual manufacturing process and have decided to complete the development and implementation of our automated manufacturing process after commercial launch. Prior to implementing commercial manufacturing of AGS-003, we would be required to demonstrate that the commercial manufacturing facility is constructed and operated in accordance with current good manufacturing practice. We would also be required to show the comparability between AGS-003 that we produce using the manual processes in our current facility and AGS-003 produced using the manual process in the commercial manufacturing facility.

If we transition to automated manufacturing processes, we expect our automated manufacturing processes will be based on existing functioning prototypes of automated devices for the production of commercial quantities of our Arcelis-based product candidates. These devices can be used to perform substantially all steps required for the manufacture of our Arcelis-based product candidates.

We do not have experience in manufacturing products on a commercial scale or using automated processes. In addition, because we are aware of only one company that has manufactured an individualized immunotherapy product for commercial sale, there are limited precedents from which we can learn. We may encounter difficulties in the manufacture of our Arcelis-based products due to our limited manufacturing experience. These difficulties could delay the build-out and equipping of a commercial manufacturing facility and regulatory approval of the manufacture of our Arcelis-based products using the facility, increase our costs or cause production delays or result in us not manufacturing sufficient product to meet our expected commercial requirements, any of which could damage our reputation and hurt our profitability. If we are unable to successfully increase our manufacturing capacity to commercial scale, our business may be materially adversely affected.

We need to establish commercial manufacturing operations and augment our manufacturing personnel in advance of any regulatory submission for approval of AGS-003. If we fail to establish commercial manufacturing operations in compliance with regulatory requirements, or augment our manufacturing personnel, we may not be able to initiate commercial operations or produce sufficient product to meet our expected commercial requirements. We have delayed the implementation of our automated manufacturing process and may not be able to use such process on a timely basis or at all.

In order to meet our business plan, which contemplates manufacturing our product first using manual processes and later using automated processes for the commercial requirements of AGS-003 and any other Arcelis-based product candidates that might be approved, we plan to lease, build out and equip a commercial

manufacturing facility and add manufacturing personnel in advance of any regulatory submission for approval of AGS-003. The planned leasing, build-out and equipping of a commercial manufacturing facility or, alternatively, the build-out and equipping of a leased commercial manufacturing facility, will require substantial capital expenditures and additional regulatory approvals. In addition, it will be costly and time consuming to recruit necessary additional personnel.

If we are unable to successfully build out and equip a commercial manufacturing facility in compliance with regulatory requirements or hire and train additional necessary manufacturing personnel appropriately, our filing for regulatory approval of AGS-003 may be delayed or denied.

We plan to delay the implementation of our automated manufacturing process, and thus plan to seek marketing approval of AGS-003 and, if approved, to initially commercially supply AGS-003 using manual manufacturing processes. Prior to implementing commercial manufacturing of AGS-003, we will be required to demonstrate that the commercial manufacturing facility is constructed and operated in accordance with current Good Manufacturing Practice, or cGMP. We will also be required to show the comparability between AGS-003 that we produce using the manual processes in our current facility and AGS-003 produced using the manual process in the new facility.

Our implementation of automated processes could take longer, particularly if we are unable to achieve any of the required tasks on a timely basis, or at all. We are collaborating with Invetech Pty Ltd., or Invetech, and Saint-Gobain Performance Plastics Corporation, or Saint-Gobain, to develop the equipment and disposables necessary to implement the automated manufacturing processes for Arcelis-based products. If Invetech or Saint-Gobain do not perform as expected under the agreements or the projects with Invetech or Saint-Gobain are unsuccessful for any other reason, our timelines for the implementation of our automated manufacturing processes could be further delayed and our business could be adversely affected.

Prior to implementing the automated manufacturing processes for Arcelis-based products, we will be required to:

We will need regulatory approval to use the automated manufacturing processes for commercial purposes. If the FDA requires us to conduct a bridging study to demonstrate comparability between AGS-003 that we produce manually and AGS-003 produced using the automated processes, the implementation of the automated manufacturing processes and the filing for such approval will likely be delayed.

If we are unable to successfully implement the automated processes required and demonstrate comparability between the AGS-003 that we produce manually and the AGS-003 produced using the automated processes, our filing for regulatory approval of the commercial use of our automated manufacturing processes may be delayed

or denied and we may not be able to initiate commercial manufacturing using our automated manufacturing processes. In such event, our commercial manufacturing costs will be higher than anticipated and we may not be able to manufacture sufficient product to meet our expected commercial requirements.

Lack of coordination internally among our employees and externally with physicians, hospitals and third-party suppliers and carriers, could cause manufacturing difficulties, disruptions or delays and cause us to not have sufficient product to meet our expected clinical trial requirements or potential commercial requirements.

Manufacturing our Arcelis-based product candidates requires coordination internally among our employees and externally with physicians, hospitals and third party suppliers and carriers. For example, a patient’s physician or clinical site will need to coordinate with us for the shipping of a patient’s disease sample and leukapheresis product to our manufacturing facility in a timely manner, and we will need to coordinate with them for the shipping of the manufactured product to them. Such coordination involves a number of risks that may lead to failures or delays in manufacturing our Arcelis-based product candidates, including:

If we are unable to coordinate appropriately, we may encounter delays or additional costs in achieving our clinical and commercialization objectives, including in obtaining regulatory approvals of our product candidates and supplying product, which could materially damage our business and financial position.

If our existing manufacturing facility or any commercial manufacturing facility that we are using is damaged or destroyed, or production at one of these facilities is otherwise interrupted, our business and prospects would be negatively affected.

We currently have a single manufacturing facility and expect that the commercial manufacturing facility that we plan to build out and equip will be our only commercial manufacturing facility in North America. If our existing manufacturing facility or the new commercial manufacturing facility that we plan to build out and equip, or the equipment in either of these facilities, is damaged or destroyed, we likely would not be able to quickly or inexpensively replace our manufacturing capacity and possibly would not be able to replace it at all. Any new facility needed to replace either our existing manufacturing facility or a new commercial manufacturing facility would need to comply with the necessary regulatory requirements, need to be tailored to our specialized

automated manufacturing requirements and require specialized equipment. We would need FDA approval before selling any products manufactured at a new facility. Such an event could delay our clinical trials or, if any of our product candidates are approved by the FDA, reduce or eliminate our product sales.

We maintain insurance coverage to cover damage to our property and equipment and to cover business interruption and research and development restoration expenses. If we have underestimated our insurance needs with respect to an interruption in our clinical manufacturing of our product candidates, we may not be able to adequately cover our losses.

If we fail to comply with our obligations under our intellectual property licenses with third parties, we could lose license rights that are important to our business.

We are a party to a number of intellectual property license agreements with third parties, including with respect to each of AGS-003 and AGS-004, and we expect to enter into additional license agreements in the future. Our existing license agreements impose, and we expect that future license agreements will impose, various diligence, milestone payment, royalty, insurance and other obligations on us. For example, under our license agreement with Duke University which relates to patents and patent applications directed towards the composition of matter of Arcelis-based products, dendritic cells loaded with RNA from tumors or pathogens, methods of manufacture of these products and methods of using these products to treat tumors, we are required to use commercially reasonable efforts to research, develop and market license products and to satisfy other specified obligations. If we fail to comply with our obligations under these licenses, our licensors may have the right to terminate these license agreements, in which event we might not be able to market any product that is covered by these agreements, or to convert the license to a non-exclusive license, which could materially adversely affect the value of the product candidate being developed under the license agreement. Termination of these license agreements or reduction or elimination of our licensed rights may result in our having to negotiate new or reinstated licenses with less favorable terms.

If we are unable to obtain and maintain patent protection for our technology and products, or if our licensors are unable to obtain and maintain patent protection for the technology or products that we license from them, or if the scope of the patent protection obtained is not sufficiently broad, our competitors could develop and commercialize technology and products similar or identical to ours, and our ability to successfully commercialize our technology and products may be adversely affected.

Our success depends in large part on our and our licensors’ ability to obtain and maintain patent protection in the United States and other countries with respect to our proprietary technology and products. We and our licensors have sought to protect our proprietary position by filing patent applications in the United States and abroad related to our novel technologies and products that are important to our business. This 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. It is also possible that we will fail to identify patentable aspects of our research and development efforts before it is too late to obtain patent protection. Moreover, in some circumstances, we do not have the right to control the preparation, filing and prosecution of patent applications, or to maintain the patents, covering technology or products that we license from third parties and are reliant on our licensors. Therefore, we cannot be certain that these patents and applications will be prosecuted and enforced in a manner consistent with the best interests of our business. If such licensors fail to maintain such patents, or lose rights to those patents, the rights we have licensed may be reduced or eliminated.

The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions and has in recent years been the subject of much litigation. As a result, the issuance, scope, validity, enforceability and commercial value of our and our licensors’ patent rights are highly uncertain. Our and our licensors’ pending and future patent applications may not result in patents being issued

which protect our technology or products or which effectively prevent others from commercializing competitive technologies and products. Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may diminish the value of our patents or narrow the scope of our patent protection.

Third parties could practice our inventions in territories where we do not have patent protection. Furthermore, the laws of foreign countries may not protect our rights to the same extent as the laws of the United States. For example, we own or exclusively license patents relating to our process of manufacturing an individualized drug product. A U.S. patent may be infringed by anyone who, without authorization, practices the patented process in the United States or imports a product made by a process covered by the U.S. patent. In foreign countries, however, importation of a product made by a process patented in that country may not constitute an infringing activity, which would limit our ability to enforce our process patents against importers in that country. Furthermore, the legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents and other intellectual property protection. This could make it difficult for us to stop the infringement of our patents or the misappropriation of our other intellectual property rights. If competitors are able to use our technologies, our ability to compete effectively could be harmed.

Furthermore, 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 or our licensors were the first to make the inventions claimed in our owned or licensed patents or pending patent applications, or that we or our licensors were the first to file for patent protection of such inventions.

Assuming the other requirements for patentability are met, in the United States, the first to invent the claimed invention is entitled to the patent, while outside the United States, the first to file a patent application is generally entitled to the patent. Under the America Invents Act, or AIA, enacted in September 2011, the United States moved to a first inventor to file system in March 2013. The United States Patent and Trademark Office only recently finalized the rules relating to these changes and courts have yet to address the new provisions. These changes could increase the costs and uncertainties surrounding the prosecution of our patent applications and the enforcement or defense of our patent rights. Furthermore, we may become involved in interference proceedings, opposition proceedings, or other post-grant proceedings, such as reissue, reexamination or inter partes review proceedings, which may challenge our patent rights or the patent rights of others. For example, we have filed an application for reissue of one of our U.S. patents directed towards methods of manufacture of dendritic cells from monocytes stored for more than six hours and up to four days without freezing. An adverse determination in any such proceeding or litigation 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.

Even if our owned and licensed 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 owned or licensed 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 scope, validity or enforceability, and our owned and licensed patents may be challenged in the courts or patent offices in the United States and abroad. Such challenges may result in patent claims being narrowed, invalidated or held unenforceable, which could limit our ability to or 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. 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. For example, certain of the U.S. patents we exclusively license from Duke University expire as early as 2016 and the European and Japanese patents exclusively licensed from Duke University expire in 2017. As a result, our owned and licensed patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours.

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

Competitors may infringe our patents. To counter such infringement or unauthorized use, we may be required to file infringement claims against third parties, which can be expensive and time consuming. In addition, during an infringement proceeding, a court may decide that the patent rights we are asserting are invalid or unenforceable, or may refuse to stop the other party from using the technology at issue on the grounds that our patents do not cover the technology in question. An adverse result in any litigation proceeding could put one or more of our patents at risk of being invalidated or interpreted narrowly. 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. In addition, our licensors may have rights to file and prosecute such claims and we are reliant on them.

Third parties may initiate legal proceedings alleging that we are infringing their intellectual property rights, the outcome of which would be uncertain and could have a material adverse effect on the success of our business.

Our commercial success depends upon our ability and the ability of our collaborators to develop, manufacture, market and sell our product candidates and use our proprietary technologies without infringing the proprietary rights of third parties. We cannot ensure that third parties do not have, or will not in the future obtain, intellectual property rights such as granted patents that could block our ability to operate as we would like. There may be patents in the United States or abroad owned by third parties that, if valid, may block our ability to make, use or sell our products in the United States or certain countries outside the United States, or block our ability to import our products into the United States or into certain countries outside the United States.

We may become party to, or threatened with, future adversarial proceedings or litigation regarding intellectual property rights with respect to our products and technology. For example, third parties may assert infringement claims against us based on existing patents or patents that may be granted in the future. If we are found to infringe a third party’s intellectual property rights, we could be required to obtain a license from such third party to continue developing and marketing our products and technology. However, we may be unable to obtain any required license on commercially reasonable terms or even obtain a license at all. Even if we were able to obtain a license, it could be non-exclusive, thereby giving our competitors access to the same technologies licensed to us. We could be forced, including by court order, to cease commercializing the infringing technology or product. In addition, we could be found liable for monetary damages. A finding of infringement could prevent us from commercializing our product candidates or force us to cease some of our business operations, which could materially harm our business. Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar negative impact on our business.

We have research licenses to certain reagents and their use in the development of our product candidates. We would need commercial licenses to these reagents for any of our product candidates that receive approval for sale in the United States. We believe that commercial licenses to these reagents will be available. However, if we are unable to obtain any such commercial licenses, we may be unable to commercialize our product candidates without infringing the patent rights of third parties. If we did seek to commercialize our product candidates without a license, these third parties could initiate legal proceedings against us.

We may be subject to claims that our employees have wrongfully used or disclosed alleged trade secrets of their former employers.

Many of our employees were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. Although we try to ensure that our employees do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or these employees have used or disclosed intellectual property, including trade secrets or other proprietary

information, of any such employee’s former employer. 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 could result in substantial costs and be a distraction to management.

Intellectual property litigation could cause us to spend substantial resources and distract our personnel from their normal responsibilities.

Even if resolved in our favor, 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. Such litigation or proceedings could substantially increase our operating losses and reduce the 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 greater financial resources. 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.

If we are unable to protect the confidentiality of our trade secrets, our business and competitive position would be harmed.

In addition to seeking patents for some of our technology and products, we also rely on trade secrets, including unpatented know-how, technology and other proprietary information, to maintain our competitive position. The types of protections available for trade secrets are particularly important with respect to our Arcelis platform’s manufacturing capabilities, which involve significant unpatented know-how. We seek to protect these trade secrets, in part, by entering into non-disclosure and confidentiality agreements with parties who have access to them, such as our employees, corporate collaborators, outside scientific collaborators, sponsored researchers, contract manufacturers, consultants, advisors and other third parties. We also enter into confidentiality and invention or patent assignment agreements with our employees and consultants. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside the United States are less willing or unwilling to protect trade secrets. If any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right 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, our competitive position would be harmed.

Any product candidate for which we obtain marketing approval could be subject to restrictions or withdrawal from the market and we may be subject to penalties if we fail to comply with regulatory requirements or if we experience unanticipated problems with our products, when and if any of them are approved.

Any product candidate for which we obtain marketing approval, along with the manufacturing processes, post-approval clinical data, labeling, advertising and promotional activities for such product, will be subject to continual requirements of and review by the FDA and other regulatory authorities. These requirements include submissions of safety and other post-marketing information and reports, registration and listing requirements, cGMP requirements relating to quality control, quality assurance and corresponding maintenance of records and documents, cGTP requirements, requirements regarding the distribution of samples to physicians and

recordkeeping. Even if regulatory approval of a product candidate is granted, the approval may be subject to limitations on the indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for costly post-marketing testing and surveillance to monitor the safety or efficacy of the product. The FDA closely regulates the post-approval marketing and promotion of drugs to ensure drugs are marketed only for the approved indications and in accordance with the provisions of the approved label. The FDA imposes stringent restrictions on manufacturers’ communications regarding off-label use and if we do not market our products for their approved indications, we may be subject to enforcement action for off-label marketing. In addition, later discovery of previously unknown problems with our products, manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may yield various results, including:

Our relationships with customers 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 criminal sanctions, civil penalties, program exclusion, contractual damages, reputational harm and diminished profits and future earnings.

Healthcare providers, physicians and third party payors play a primary role in the recommendation and prescription of any product candidates for which we obtain marketing approval. Our future arrangements with third party payors and customers 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 the following:

Some state laws require pharmaceutical companies to comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government and may require drug manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers or marketing expenditures. State and foreign laws also govern the privacy and security of health information in some circumstances, many of which differ from each other in significant ways and often are not preempted by the federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, thus complicating compliance efforts.

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 or case law involving applicable fraud and abuse or other healthcare laws and regulations. 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, exclusion from government funded healthcare programs, such as Medicare and Medicaid, and the curtailment or restructuring of our operations. If any of the physicians or other providers or entities with whom we expect to do business are found to be not in compliance with applicable laws, they may be subject to criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs.

Recently enacted and future legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize our product candidates and affect the prices we may obtain.

In the United States and some foreign jurisdictions, there have been 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 to profitably sell any product candidates for which we obtain marketing approval.

In the United States, the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, or Medicare Modernization Act, changed the way Medicare covers and pays for pharmaceutical products. The legislation expanded Medicare coverage for drug purchases by the elderly and introduced a new reimbursement methodology based on average sales prices for physician administered drugs. In addition, this legislation

provided authority for limiting the number of drugs that will be covered in any therapeutic class in certain cases. Cost reduction initiatives and other provisions of this and other more recent legislation could decrease the coverage and reimbursement that is provided for any approved products. While the Medicare Modernization Act applies only to drug benefits for Medicare beneficiaries, private payors often follow Medicare coverage policy and payment limitations in setting their own reimbursement rates. Therefore, any reduction in reimbursement that results from the Medicare Modernization Act or other more recent legislation may result in a similar reduction in payments from private payors.

In March 2010, President Obama signed into law the Health Care Reform Law, a sweeping law intended to broaden access to health insurance, reduce or constrain the growth of healthcare spending, enhance remedies against fraud and abuse, add new transparency requirements for health care and health insurance industries, impose new taxes and fees on the health industry and impose additional health policy reforms. Effective October 1, 2010, the Health Care Reform Law revises the definition of “average manufacturer price” for reporting purposes, which could increase the amount of Medicaid drug rebates to states. Further, the new law imposes a significant annual fee on companies that manufacture or import branded prescription drug products. Substantial new provisions affecting compliance have also been enacted, which may affect our business practices with health care practitioners. We will not know the full effects of the Health Care Reform Law until applicable federal and state agencies issue regulations or guidance under the new law. Although it is too early to determine the effect of the Health Care Reform Law, the new law appears likely to continue the pressure on pharmaceutical pricing, especially under the Medicare program, and may also increase our regulatory burdens and operating costs.

Legislative and regulatory proposals have been made to expand post-approval requirements and restrict sales and promotional activities for pharmaceutical 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 U.S. Congress of the FDA’s approval process may significantly delay or prevent marketing approval, as well as subject us to more stringent product labeling and post-marketing testing and other requirements.

With the enactment of the Biologics Price Competition and Innovation Act of 2009, or BPCIA, as part of the Health Care Reform Law, an abbreviated pathway for the approval of biosimilar and interchangeable biological products was created. The new abbreviated regulatory pathway establishes legal authority for the FDA to review and approve biosimilar biologics, including the possible designation of a biosimilar as “interchangeable” based on its similarity to an existing brand product. Under the BPCIA, an application for a biosimilar product cannot be submitted to the FDA until four years, or approved by the FDA until 12 years, after the original brand product identified as the reference product was approved under a BLA. The new law is complex and is only beginning to be interpreted and implemented by the FDA. As a result, its ultimate impact, implementation and meaning is subject to uncertainty. While it is uncertain when any such processes may be fully adopted by the FDA, any such processes could have a material adverse effect on the future commercial prospects for our biological products.

We believe that if any of our product candidates were to be approved as biological products under a BLA, such approved products should qualify for the four-year and 12-year periods of exclusivity. However, there is a risk that the U.S. Congress could amend the BPCIA to significantly shorten these exclusivity periods as proposed by President Obama, or that the FDA will not consider our product candidates to be reference products for competing products, potentially creating the opportunity for generic competition sooner than anticipated. Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of our reference products in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

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 the success of 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 radioactive 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 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 biological, hazardous or radioactive 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 production efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

Our future success depends on our ability to retain our chief executive officer and other key executives and to attract, retain and motivate qualified personnel.

We are highly dependent on Jeffrey Abbey, our President and Chief Executive Officer, Charles Nicolette, our Vice President of Research and Development and Chief Scientific Officer, Lee F. Allen, our Chief Medical Officer, and Richard Katz, our Vice President and Chief Financial Officer, as well as the other principal members of our management and scientific teams. Although we have formal employment agreements with each of our executive officers, these agreements do not prevent our executives from terminating their employment with us at any time. We do not maintain “key person” insurance for any of our executives or other employees. 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 and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us.

We expect to expand our development, regulatory, manufacturing and 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, regulatory affairs, manufacturing and 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.

After this offering, our executive officers, directors and affiliates of all officers and directors who own our outstanding common stock will maintain the ability to control all matters submitted to stockholders for approval.

Upon the closing of this offering, our executive officers, directors and affiliates of our executive officers and directors together will beneficially own, in the aggregate, shares representing approximately 64.77% of our outstanding common stock, assuming certain of our existing principal stockholders, which are affiliated with certain of our directors and have indicated an interest in purchasing an aggregate of up to approximately $21.5 million in shares of our common stock and warrants in this offering at the public offering price, purchase all the shares and accompanying warrants that they have indicated an interest in purchasing. As a result, following this offering, if these stockholders were to choose to act together, they would be able to control all 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 on terms that other stockholders may desire.

Our largest stockholder, Pharmstandard, could continue to exert significant influence over us after this offering and could limit your ability to influence the outcome of key transactions, including any change of control.

Upon the closing of this offering, our largest stockholder, Pharmstandard will beneficially own, in the aggregate, shares representing approximately 38.72% of our outstanding common stock, assuming Pharmstandard purchases all the shares of our common stock and accompanying warrants in this offering at the public offering price that it has indicated an interest in purchasing.

Following this offering, we expect that Pharmstandard will continue to be able to exert significant influence over our business. Pharmstandard may have interests that differ from your interests, and it may vote in a way with which you disagree and that may be adverse to your interests. The concentration of ownership of our capital stock may have the effect of delaying, preventing or deterring a change of control of our company, could deprive our stockholders of an opportunity to receive a premium for their common stock as part of a sale of our company and may adversely affect the market price of our common stock.

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 corporate charter and our bylaws 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:

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.

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

The price of our common stock and accompanying warrants in this offering is substantially higher than the net tangible book value per share of our common stock. Therefore, if you purchase shares of our common stock and accompanying warrants in this offering, you will pay a price per share of common stock and accompanying warrant that substantially exceeds our net tangible book value per share after giving effect to this offering. To the extent outstanding options or warrants are exercised, including any warrants issued in this offering, you will incur further dilution. At the public offering price of $5.50 per share of common stock and accompanying warrant, you will experience immediate dilution of $4.06 per share, representing the difference between our pro forma net tangible book value per share, after giving effect to this offering, and the public offering price.

An active trading market for our common stock may not be sustained following this offering.

Although our common stock is listed on The NASDAQ Global Market, an active trading market for our shares may not be sustained. If an active market for our common stock is not sustained, it may be difficult for you to sell your shares, including shares you may purchase in this offering, without depressing the market price for the shares or sell your shares at all. Any inactive trading market for our common stock may also impair our ability to raise capital to continue to fund our operations by selling shares and may impair our ability to acquire other companies or technologies by using our shares as consideration.

There is no public market for the warrants to purchase shares of our common stock being offered by us in this offering.

There is no established public trading market for the warrants being offered in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the warrants on any national securities

exchange or other nationally recognized trading system, including the Nasdaq Global Market. Without an active market, the liquidity of the warrants will be limited.

If our stock price continues to be volatile, purchasers of our common stock or warrants could incur substantial losses.

Our stock price is likely to be volatile. For example, our stock has traded in a range from a low of $1.61 and high of $13.97 during the period of February 7, 2014 through July 27, 2016. The stock market in general and the market for 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 public offering price. The market price for our common stock may be influenced by many factors, including:

We will continue to incur increased costs as a result of operating as a public company, and our management will be required to devote substantial time to new compliance initiatives and corporate governance practices.

Pursuant to Section 404 of the Sarbanes-Oxley Act of 2002, we are required to furnish a report by our management on our internal control over financial reporting. 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 of the Sarbanes-Oxley Act of 2002 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. If we identify one or more material weaknesses, it could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

We are an “emerging growth company,” and the reduced disclosure requirements applicable to emerging growth companies may make our common stock less attractive to investors.

We are an “emerging growth company,” as defined in the JOBS Act, and may remain an emerging growth company for up to five years. For so long as we remain an emerging growth company, we are permitted and plan 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, 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, 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 our 2015 Annual Report on Form 10-K, we did not include 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. This allows an emerging growth company to delay the adoption of certain accounting standards 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, we will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

We have broad discretion in the use of the net proceeds from this offering and our use of these proceeds may not enhance our results of operations.

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

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

We have never declared or paid cash dividends on our capital stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business. In September 2014, we entered into a venture loan and security agreement with Horizon and Fortress. The terms of this agreement 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.

A significant portion of our total outstanding shares is restricted from immediate resale but may be sold into the market in the near future, which could cause the market price of our common stock to decline significantly, even if our business is doing well.

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 of common stock intend

to sell shares, could reduce the market price of our common stock. After this offering, we will have 41,122,361 shares of common stock outstanding based on the 32,031,452 shares outstanding as of June 30, 2016, without giving effect to any exercise of the warrants being issued in this offering. Of these shares, 17,374,066 are subject to a contractual lock-up with the underwriters for this offering for a period of 90 days following this offering. These shares can be sold, subject to any applicable volume limitations under federal securities laws, after the earlier of the expiration of, or release from, the 90-day lock-up period. The balance of our outstanding shares of common stock may be freely sold in the public market at any time. Moreover, certain holders of our common stock have rights, subject to 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. Pursuant to the registration rights agreement entered into in connection with our private placement of common stock and warrants to purchase common stock in March 2016, we filed a registration statement on July 22, 2016 to register for resale the shares of common stock, and the shares of common stock issuable upon the exercise of warrants, issued upon the closing of the second tranche of the March 2016 financing as well as other shares of common stock held by participants in such offering.

In addition, as of June 30, 2016, there were 4,422,086 shares subject to outstanding options under our equity incentive plans, all of which shares we have registered under the Securities Act of 1933, as amended, which we refer to as the Securities Act, on a registration statement on Form S-8. These shares, once vested and issued upon exercise, will be able to be freely sold in the public market, subject to volume limits applicable to affiliates and the lock-up agreements described above, to the extent applicable. Furthermore, as of June 30, 2016, there were 6,931,109 shares subject to outstanding warrants. In addition, the warrants being issued in this offering will be outstanding. The shares issuable upon exercise of these warrants will become eligible for sale in the public market to the extent such warrants are exercised and to the extent permitted by Rule 144 under the Securities Act.

If securities or industry analysts do not publish research or publish inaccurate or unfavorable research about our business, our share price and trading volume could decline.

The trading market for our common stock will depend on the research and reports that securities or industry analysts publish about us or our business. We do not have any control over these analysts. There can be no assurance that analysts will cover us, or provide favorable coverage. If one or more analysts downgrade our stock or change their opinion of our stock to be less favorable, our share price would likely decline. In addition, if one or more analysts cease coverage of our company or fail to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.

We estimate that the net proceeds we will receive from this offering will be approximately $48.2 million after deducting underwriting discounts and commissions and estimated offering expenses payable by us and excluding the proceeds, if any, from the exercise of the warrants issued in this offering.

We intend to use the net proceeds from this offering, together with our cash, cash equivalents and short-term investments, to fund our pivotal Phase 3 ADAPT trial of AGS-003, the ongoing and planned investigator-initiated Phase 2 clinical trials of AGS-003, our share of the expected costs of the leasing, build-out and equipping of a commercial manufacturing facility and activities in preparation for the submission of a BLA to the FDA for AGS-003, and for working capital and other general corporate purposes.

The expected use of net proceeds from this offering represents our intentions based upon our current plans and business conditions. The amounts and timing of our actual expenditures may vary significantly depending on numerous factors, including the status of and results from clinical trials of AGS-003 and whether regulatory authorities require us to perform additional clinical trials of AGS-003 in order to obtain marketing approvals. As a result, our management will retain broad discretion over the allocation of the net proceeds from this offering. We may find it necessary or advisable to use the net proceeds from this offering for other purposes, and we will have broad discretion in the application of net proceeds.

As of March 31, 2016, we had cash, cash equivalents and short-term investments of $13.8 million and working capital of $0.9 million. As of June 30, 2016, we had cash, cash equivalents and short-term investments of $34.8 million. Based on our current operating plan, we expect that the net proceeds from this offering, together with our existing cash, cash equivalents and short-term investments as of June 30, 2016, will enable us to fund our operating expenses through the third quarter of 2017. We expect that our available funds following this offering will be sufficient to fund our operations until such time as there are a sufficient number of events to permit the primary analysis and assessment of overall survival in the ADAPT trial and our share of the expected costs of the leasing, build-out and equipping of a commercial manufacturing facility assuming that we enter into the contemplated arrangements related to the facility. We expect that these funds will not, however, be sufficient to enable us to complete required activities in preparation for the submission of a BLA to the FDA for AGS-003, to commercially launch AGS-003 or to complete the build-out and equipping of a commercial manufacturing facility without entering into such arrangements related to the facility. These expectations are based on our current operating plan under which we implemented measures to reduce our operating expenses, including, among other measures, reductions in spending for activities in preparation for submission of a BLA and workforce reduction action plan designed to streamline operations and reduce our operating expenses. Under our plan, we also intend to seek to refinance our existing venture loan facility with Horizon, and Fortress under which we are required to begin making principal payments in October 2016. If we are unable to refinance this facility and are required to begin making principal payments, we expect that the net proceeds from this offering, together with our existing cash, cash equivalents and short-term investments as of June 30, 2016, would only fund our operating expenses through the second quarter of 2017. We also intend to seek to enter into collaborations for the development, marketing and distribution of AGS-003 outside North America and of our non-oncology product candidates, including AGS-004. If we are unable to refinance our venture loan facility or enter into any such collaborations, we may be required to implement additional measures to materially reduce our operating expenses, which could adversely affect our business and operations. It is also possible that our available funds will not enable us to reach a sufficient number of events to permit the primary analysis and assessment of overall survival in the ADAPT trial because the actual costs and timing of clinical trials are difficult to predict and are subject to substantial risks and delays.

committed to this project. We are also actively exploring other financing arrangements using a contract manufacturing organization that may provide for a reduced investment by us. We expect to enter into an arrangement for a commercial manufacturing facility in the second half of 2016 and that such arrangement will likely involve material obligations. If we are unable to enter into such arrangements on the anticipated terms, on a timely basis or at all, we may not be able to complete the planned leasing, build-out and equipping of a commercial facility, or may be delayed in doing so, which in either case would delay the commercialization of AGS-003.

Pending our use of the net proceeds from this offering, we intend to invest the net proceeds in a variety of capital preservation investments, including short-term, investment-grade, interest-bearing instruments and U.S. government securities.

Further, the net proceeds from this offering will reduce in full the dollar amount committed to be purchased in the third tranche of our March 2016 financing, and as a result we will have no further ability to effect the closing of the third tranche of the March 2016 financing.

Our common stock has been listed on The NASDAQ Global Market under the symbol “ARGS” since February 7, 2014. Prior to that date, there was no public market for our common stock. The following table sets forth, for the quarterly periods indicated, the high and low intraday sale price per share of our common stock as reported on The NASDAQ Global Market:

On July 27, 2016, the last sale price of our common stock, as reported on The NASDAQ Global Market, was $6.46 per share.

We have never declared or paid any cash dividends on our capital stock. We currently intend to retain earnings, if any, to finance the growth and development of our business. We do not expect to pay any cash dividends on our common stock in the foreseeable future. Payment of future dividends, if any, will be at the discretion of our board of directors and will depend on our financial condition, results of operations, capital requirements, restrictions contained in current or future financing instruments, provisions of applicable law and other factors the board deems relevant. Our ability to pay dividends on our common stock is precluded by the terms of our venture loan and security agreement with Horizon Technology Finance Corporation and Fortress Credit Co LLC and may be further restricted by the terms of any of our future indebtedness. See “Risk Factors—Risks Related to Our Financial Position and Need for Additional Capital—Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our technologies or product candidates” and “Risk Factors—Risks Related to Our Common Stock and This Offering—Because we do not anticipate paying any cash dividends on our capital stock in the foreseeable future, capital appreciation, if any, will be your sole source of gain” in this prospectus supplement.

The following table sets forth our cash, cash equivalents and short-term investments and capitalization as of March 31, 2016, as follows:

You should read this table together with our consolidated financial statements and the related notes thereto and the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2015 and Quarterly Report on Form 10-Q for the quarter ended March 31, 2016, each of which is incorporated by reference in this prospectus supplement.

If you invest in our securities in this offering, your interest will be diluted immediately to the extent of the difference between the public offering price per share of common stock and accompanying warrant you will pay in this offering and the pro forma as adjusted net tangible book value per share of our common stock after this offering. Our historical net tangible book value as of March 31, 2016 was negative $20.2 million, or $(0.79) per share of common stock. Our historical net tangible book value per share represents our total tangible assets less total liabilities, divided by the number of shares of our common stock outstanding on March 31, 2016.

Our pro forma net tangible book value as of March 31, 2016 was $9.7 million, or $0.31 per share of our common stock. Pro forma net tangible book value per share represents our total tangible assets reduced by the amount of our total liabilities, divided by the total number of shares of our common stock outstanding after giving effect to the issuance of 5,478,672 shares of common stock and warrants to purchase 4,109,005 shares of common stock, and the receipt of net proceeds of$ 29.8 million therefrom upon the closing of the second tranche of our March 2016 financing in June 2016.

After giving effect to our issuance and sale of 9,090,909 shares of common stock and accompanying warrants in this offering at the public offering price of $5.50 per share of common stock and accompanying warrant, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us and excluding the proceeds, if any, from the exercise of the warrants issued in this offering, the pro forma as adjusted net tangible book value as of March 31, 2016 would have been $57.9 million, or $1.44 per share. This represents an immediate increase in pro forma as adjusted net tangible book value to existing stockholders of $1.13 per share. The public offering price per share of common stock and accompanying warrant significantly exceeds the pro forma as adjusted net tangible book value per share. Accordingly, new investors who purchase shares of common stock and warrants in this offering will suffer an immediate dilution of their investment of $4.06 per share. The following table illustrates this per share dilution to the new investors purchasing shares of common stock and accompanying warrants in this offering:

The number of shares of our common stock to be outstanding after this offering as reflected in the calculations above is based on the 25,639,662 shares of our common stock outstanding as of March 31, 2016 excludes the shares of common stock issuable upon exercise of the warrants being offered by us in this offering and also excludes the following:

The following description of our common stock and warrants summarizes the material terms and provisions thereof, including the material terms of the common stock and warrants we are offering under this prospectus supplement and the accompanying prospectus.

The material terms and provisions of our common stock are described under the caption “Description of Capital Stock” starting on page 17 of the accompanying prospectus. Our common stock is listed on the NASDAQ Global Market under the symbol “ARGS.”

The following is a brief summary of certain terms and conditions of the warrants and is subject in all respects to the provisions contained in the warrants. You should review a copy of the form of warrant agreement for a complete description of the terms and conditions applicable to the warrants.

Form. The warrants will be issued either in physical certificated form or in book-entry form to the investors.

Term. The warrants will become exercisable on August 2, 2016 and remain exercisable during the period ending at 5:30 P.M. on August 2, 2021.

Exercise Price. The exercise price of the warrants is $5.50 per share. The exercise price is subject to appropriate adjustment in the event of certain stock dividends and distributions, stock splits, stock combinations, stock issuances, reclassifications or similar events affecting our common stock, but need not be adjusted if such adjustment would result in the exercise price being reduced to less than the par value of the warrant shares.

Exercisability. Holders may exercise the warrants beginning on August 2, 2016 and at any time thereafter during the applicable term of the warrant. The warrants will be exercisable, at the option of each holder, in whole or in part, by delivering to us a duly executed exercise notice and payment in full for the number of shares of our common stock purchased upon such exercise. In the event that the registration statement relating to the warrant shares is not effective or the warrant holder is restricted from selling warrant shares due to a blackout period under our corporate trading policy, the warrant holder will have the right to exercise its warrant for a net number of warrant shares pursuant to the cashless exercise procedures specified in the warrant. The exercise of the warrants is subject to limits as described below under the caption “—Exercise Limitations.”

No Fractional Shares. No fractional shares or scrip representing fractional shares shall be issued upon the exercise of the warrants. As to any fraction of a share which the holder would otherwise be entitled to purchase upon such exercise, we shall cause the warrant agent to pay a cash adjustment in respect of such final fraction in an amount equal to such fraction multiplied by the exercise price of the warrant per whole share.

Transferability. Subject to applicable laws and the restriction on transfer set forth in the warrant, the warrant may be transferred at the option of the holder in accordance with the procedures set forth in the warrant.

Authorized Shares. During the period the warrants are outstanding, we will reserve from our authorized and unissued shares of common stock a sufficient number of shares to provide for the issuance of shares of common stock underlying the warrants upon the exercise of the warrants. In the event we ever fail to have reserved sufficient authorized and unissued shares to provide for the issuance of shares underlying the warrants, we are required to hold a meeting of stockholders within 90 days of such failure to increase the number of authorized shares to cover the issuance of shares of common stock underlying the warrants.

Exchange Listing. We do not plan on applying to list the warrants on The NASDAQ Global Market, any other national securities exchange or any other nationally recognized trading system.

Fundamental Transactions. In the event of any fundamental transaction, as described in the warrants and generally including any merger with or into another entity, sale of all or substantially all of our assets, tender offer or exchange offer, reclassification of our common stock or the consummation of a transaction whereby another entity acquires more than 50% of our outstanding voting stock, then upon any subsequent exercise of a warrant the holder shall have the right to receive as alternative consideration, for each share of common stock that would have been issuable upon such exercise immediately prior to the occurrence of such fundamental transaction, the number of shares of common stock or other equity securities of the successor or acquiring corporation or of our company, if it is the surviving corporation, and any additional consideration receivable upon or as a result of such transaction by a holder of the number of shares of common stock for which the warrant is exercisable immediately prior to such event. In addition, in the event of a fundamental transaction, then we or the successor entity shall at the holder’s option, exercisable at any time within 90 days after the consummation of the fundamental transaction, purchase the holder’s warrant for an amount of cash equal to the value of the warrant as determined in accordance with the Black Scholes option pricing model on the date of the consummation of the fundamental transaction.

Exercise Limitations. Unless, immediately prior to becoming a warrant holder, a warrant holder elects to not be subject to this provision, a warrant holder will not have the right to exercise any portion of the warrant if the holder, together with its affiliates, would beneficially own more than 4.99% of the number of shares of common stock outstanding immediately after the exercise. The warrant holder is entitled, by giving notice to us, to increase this limit up to 9.99%. Any increase to this limit by the warrant holder will not be effective until the 61^st day after such notice is delivered to us.

Right as a Shareholder. Except as otherwise provided in the warrants or by virtue of such holder’s ownership of our common stock, the holders of the warrants do not have the rights or privileges of holders of our common stock, including any voting rights, until they exercise their warrants.

Waivers and Amendments. Any term of the warrants issued in the offering may be amended or waived with our written consent and the written consent of holders representing at least 67% of the shares of common stock issuable upon exercise of the warrants then outstanding, provided, that no modification of the terms upon which the warrants are exercisable or reduction of the percentage required for consent to modification of the warrants may be made without the consent of each warrant holder affected thereby. We may also amend the provisions of any warrant with written consent of the holder of such warrant.

Warrant Agent. Our warrant agent is Computershare Inc. and Computershare Trust Company, N.A.

The following is a discussion of material U.S. federal income and estate tax considerations relating to the acquisition, ownership and disposition of shares of our common stock and warrants.

This discussion is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, which we refer to as the Code, existing and proposed U.S. Treasury Regulations promulgated thereunder, current administrative rulings and judicial decisions, all as in effect as of the date of this prospectus supplement and all of which are subject to change or to differing interpretation, possibly with retroactive effect. Any such change could alter the tax consequences described in this prospectus. In addition, the Internal Revenue Service, or the IRS, could challenge one or more of the tax consequences described in this prospectus.

We assume in this discussion that the shares of common stock and warrants will be held as capital assets (generally, property held for investment). This discussion does not address all aspects of U.S. federal income and estate taxation, including the Medicare contribution tax, that may be relevant to a particular holder in light of that holder’s individual circumstances nor does it address any aspects of U.S. state, local or non-U.S. taxes. This discussion also does not address the special tax rules applicable to particular holders, such as:

In addition, this discussion does not address the tax treatment of partnerships or other pass-through entities or persons who hold our common stock and warrants through partnerships or other entities which are pass-through entities for U.S. federal income tax purposes. A partner in a partnership or other pass-through entity that will hold our common stock and warrants should consult his, her or its own tax advisor regarding the tax consequences of the ownership and disposition of our common stock and warrants through a partnership or other pass-through entity, as applicable.

Prospective investors should consult their own tax advisors regarding the U.S. federal, state, local and non-U.S. income and other tax considerations of acquiring, holding and disposing of our common stock and warrants.

For U.S. federal income tax purposes, a holder’s acquisition of the common stock and warrants will be treated as the acquisition of an “investment unit” consisting of one share of common stock and a warrant to acquire 0.75 shares of our common stock, subject to adjustment. The purchase price for each investment unit will be allocated between these two components in proportion to their relative fair market values at the time the unit is purchased by the holder. This allocation of the purchase price for each unit will establish the holder’s initial tax basis for U.S. federal income tax purposes in the common stock and the warrant included in each unit. Each holder should consult his, her or its own tax advisor regarding the allocation of the purchase price for a unit.

This section is addressed to U.S. holders of the common stock and warrants. For purposes of this discussion, a “U.S. holder” is a beneficial owner (other than a partnership or other pass-through entity) of our common stock and warrants that is, for U.S. federal income tax purposes:

As discussed under “Dividend Policy,” we do not expect to pay cash dividends to holders of our common stock in the foreseeable future. In the event that we do make distributions on our common stock, those distributions generally will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the U.S. holder’s investment, up to such holder’s tax basis in the common stock. Any remaining excess will be treated as capital gain, subject to the tax treatment described below under the heading “Gain on Disposition of Common Stock.”

Gain or loss realized on the sale or other disposition of our common stock will be capital gain or loss. The amount of a U.S. holder’s gain or loss will be equal to the difference between the U.S. holder’s tax basis in the common stock disposed of and the amount realized on the disposition. The deductibility of capital losses is subject to limitations. Any capital gain or loss realized on a sale or other disposition of our common stock will generally be long-term capital gain or loss if the U.S. holder’s holding period for the common stock is more than one year at the time of the sale or disposition.

Upon the sale or other disposition of a warrant (other than by exercise), a U.S. holder will generally recognize capital gain or loss equal to the difference between the amount realized on the sale or other disposition and the U.S. holder’s tax basis in the warrant. This capital gain or loss will be long-term capital gain or loss if, at the time of the sale or other disposition, the warrant has been held by the U.S. holder for more than one year. The deductibility of capital losses is subject to limitations.

In general, a U.S. holder will not be required to recognize income, gain or loss upon exercise of a warrant for its exercise price, except with respect to cash received in lieu of a fractional share. The U.S. holder’s basis in a share of common stock received upon exercise will be equal to the sum of (1) the holder’s basis in the warrant and (2) the exercise price of the warrant, less any portion of the tax basis attributable to the receipt of cash in lieu of a fractional share. The U.S. holder’s holding period in the shares received upon exercise will commence on the day after the warrant is exercised. A U.S. holder’s receipt of cash in lieu of a fractional share will generally be treated as if such U.S. Holder had received the fractional share upon exercise of the warrant and then received such cash in redemption of such share.

In certain limited circumstances, a U.S. holder may be permitted to undertake a cashless exercise of warrants into our common stock. The U.S. federal income tax treatment of a cashless exercise of warrants into our common stock is unclear, and the tax consequences of a cashless exercise could differ from the consequences upon the exercise of a warrant described in the preceding paragraph. U.S. Holders should consult their own tax advisors regarding the U.S. federal income tax consequences of a cashless exercise of warrants.

If a warrant expires without being exercised, the U.S. holder will recognize a capital loss in an amount equal to the U.S. holder’s basis in the warrant. Such loss will be long-term capital loss if, at the time of the expiration, the warrant has been held by the U.S. holder for more than one year. The deductibility of capital losses is subject to limitations.

Under Section 305 of the Code, an adjustment to the number of shares of our common stock that will be issued on the exercise of the warrants, or an adjustment to the exercise price of the warrants, may be treated as a constructive distribution to a U.S. holder of the warrants if, and to the extent that, such adjustment has the effect of increasing such U.S. holder’s proportionate interest in our “earnings and profits” or assets, depending on the circumstances of such adjustment (for example, if such adjustment is to compensate for a distribution of cash or other property to our shareholders). For more information regarding the tax considerations related to distributions, see the discussion above regarding “Dividends on Common Stock.” U.S. holders should consult their tax advisors regarding the proper treatment of any adjustments to the warrants.

Information returns may be filed with the IRS with respect to dividends or other distributions we pay to a U.S. holder and proceeds from the sale of a U.S. holder’s shares of common stock or warrants. A U.S. holder will be subject to backup withholding on these payments if the holder fails to provide the holder’s taxpayer identification number to the paying agent and comply with certain certification procedures or otherwise establish an exemption from backup withholding. Backup withholding is not an additional tax. Any amounts withheld with respect to shares of common stock or warrants under the backup withholding rules will be refunded to the U.S. stockholder or credited against the holder’s United States federal income tax liability, if any, provided that certain required information is furnished to the IRS in a timely manner.

This section is addressed to non-U.S. holders of the warrants and common stock. For purposes of this discussion, a “non-U.S. holder” is a beneficial owner of our warrants and common stock (other than an entity treated as a partnership for U.S. federal income tax purposes) that is not a U.S. holder.

As discussed under “Dividend Policy,” we do not expect to pay cash dividends to holders of our common stock in the foreseeable future. If we make distributions on our common stock, those distributions generally will constitute dividends for U.S. federal income tax purposes to the extent described in “—U.S. Holders—Dividends on Common Stock.” Any such distributions will also be subject to the discussion below under the section titled “FATCA.” In addition, dividends paid to a non-U.S. holder generally will be subject to withholding of U.S. federal income tax at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States and such holder’s country of residence.

Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States, and if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt

from the 30% withholding tax if the non-U.S. holder satisfies applicable certification and disclosure requirements. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same graduated U.S. federal income tax rates applicable to U.S. persons (as defined in the Code), subject to an applicable income tax treaty providing otherwise. Any U.S. effectively connected income received by a non-U.S. holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States and such holder’s country of residence.

A non-U.S. holder of our common stock who claims the benefit of an applicable income tax treaty between the United States and such holder’s country of residence generally will be required to provide a properly executed IRS Form W-8BEN or W-8BEN-E (or successor form) and satisfy applicable certification and other requirements. Non-U.S. holders are urged to consult their own tax advisors regarding their entitlement to benefits under a relevant income tax treaty.

A non-U.S. holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim with the IRS.

A non-U.S. holder, other than with respect to gain recognized with respect to cash received in lieu of a fractional share, which will be treated as discussed below under “Gain on Disposition of Common Stock or Warrants”, generally will not be subject to U.S. federal income tax on the exercise of the warrants into shares of common stock. The U.S. federal income tax treatment of a cashless exercise of warrants into our common stock is unclear. A non-U.S. holder should consult his, her, or its own tax advisor regarding the U.S. federal income tax consequences of a cashless exercise of warrants.

Subject to the discussion below under the section titled “FATCA”, a non-U.S. holder generally will not be subject to U.S. federal income tax on gain realized on a disposition of our common stock (or any gain realized as a result of a distribution on our common stock as described in “—U.S. Holders—Dividends on Common Stock”) or warrants unless:

Although there can be no assurance, we believe that we are not currently, and we do not anticipate becoming, a “U.S. real property holding corporation” for U.S. federal income tax purposes.

No assurance can be provided that our common stock will be regularly traded on an established securities market for purposes of the rule described above.

As described under “—U.S. Holders—Constructive Dividends on Warrants”, an adjustment to the warrants could result in a constructive distribution to a non-U.S. holder, which would be treated as described under “Dividends” above. Any resulting withholding tax attributable to deemed dividends would be collected from other amounts payable or distributable to the non-U.S. holder. Non-U.S. holders should consult their tax advisors regarding the proper treatment of any adjustments to the warrants.

We must report annually to the IRS and to each non-U.S. holder the gross amount of the distributions on our common stock paid to such holder and the tax withheld, if any, with respect to such distributions. Non-U.S. holders may have to comply with specific certification procedures to establish that the holder is not a U.S. person (as defined in the Code) in order to avoid backup withholding at the applicable rate, currently 28%, with respect to dividends on our common stock. Generally, a holder will comply with such procedures if it provides a properly executed IRS Form W-8BEN or W-8BEN-E (or other applicable Form W-8) or otherwise meets documentary evidence requirements for establishing that it is a non-U.S. holder, or otherwise establishes an exemption. Dividends paid to non-U.S. holders subject to withholding of U.S. federal income tax, as described above under the heading “Dividends,” will generally be exempt from U.S. backup withholding.

Information reporting and backup withholding generally will apply to the proceeds of a disposition of our common stock or warrants by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker. Non-U.S. holders should consult their own tax advisors regarding the application of the information reporting and backup withholding rules to them.

Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is incorporated under the provisions of a specific treaty or agreement.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder can be refunded or credited against the non-U.S. holder’s U.S. federal income tax liability, if any, provided that an appropriate claim is timely filed with the IRS.

Common stock owned or treated as owned by an individual who is a non-U.S. holder (as specially defined for U.S. federal estate tax purposes) at the time of death will be included in the individual’s gross estate for U.S. federal estate tax purposes and, therefore, may be subject to U.S. federal estate tax, unless an applicable estate tax or other treaty provides otherwise. The foregoing may also apply to warrants.

Provisions of the Code commonly referred to as the Foreign Account Tax Compliance Act, or FATCA, generally impose a 30% withholding tax on dividends on, and gross proceeds from the sale or other disposition of, our stock and warrants if paid to a non-U.S. entity unless (i) if the non-U.S. entity is a “foreign financial institution,” the non-U.S. entity undertakes certain due diligence, reporting, withholding, and certification obligations, (ii) if the non-U.S. entity is not a “foreign financial institution,” the non-U.S. entity identifies certain of its U.S. investors, if any, or (iii) the non-U.S. entity is otherwise exempt under FATCA.

Withholding under FATCA generally (1) applies to payments of dividends on our common stock or warrants and (2) will apply to payments of gross proceeds from a sale or other disposition of our common stock or warrants made after December 31, 2018. An intergovernmental agreement between the United States and an applicable foreign country may modify the requirements described in this section. Under certain circumstances, a holder may be eligible for refunds or credits of the tax. Holders should consult their own tax advisors regarding the possible implications of FATCA on their investment in our common stock and warrants.

The preceding discussion of material U.S. federal tax considerations is for information only. It is not tax advice. Prospective investors should consult their own tax advisors regarding the particular U.S. federal, state, local and non-U.S. tax consequences of purchasing, holding and disposing of our common stock and warrants, including the consequences of any proposed changes in applicable laws.

Subject to the terms and conditions set forth in an underwriting agreement among us and the underwriters named below, we have agreed to sell to the underwriters, and each of the underwriters has agreed, severally and not jointly, to purchase from us, the number of shares of our common stock and accompanying warrants set forth opposite its name below.

Each share of common stock is being sold together with a warrant to purchase up to 0.75 of a share of common stock. The common stock and warrants will be issued separately. There is no market through which the warrants may be sold and purchasers may not be able to resell the warrants purchased in this offering.

The underwriting agreement provides that the obligations of the several underwriters to pay for and accept delivery of the shares of our common stock and accompanying warrants offered by this prospectus supplement are subject to the approval of certain legal matters by their counsel and to certain other conditions. The underwriters are obligated to take and pay for all of the shares of our common stock and accompanying warrants offered by this prospectus supplement if any such shares are taken. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of the non-defaulting underwriters may be increased.

Certain of our existing principal stockholders have indicated an interest in purchasing an aggregate of up to approximately $21.5 million in shares of our common stock and accompanying warrants in this offering at the public offering price. However, because indications of interest are not binding agreements or commitments to purchase, these stockholders may determine to purchase fewer shares and warrants than they indicate an interest in purchasing or not to purchase any shares and warrants in this offering. It is also possible that these stockholders could indicate an interest in purchasing more shares of our common stock and warrants. In addition, the underwriters could determine to sell fewer shares and warrants to any of these stockholders than the stockholders indicate an interest in purchasing or not to sell any shares and warrants to these stockholders. The underwriters will not receive any underwriting discount on the sale of shares of common stock and accompanying warrants to these existing stockholders.

The underwriters expect to deliver the shares of common stock and accompanying warrants to purchasers on or about August 2, 2016.

The underwriters have advised us that they propose initially to offer the shares and the accompanying warrants to the public at the combined offering price set forth on the cover page of this prospectus supplement and to dealers at that price less a concession not in excess of $0.198 per share of common stock and accompanying warrant. After the initial offering, the offering price, concession or any other term of this offering may be changed.

The following table shows the offering price, underwriting discounts and commissions (other than in connection with the sale of shares of our common stock to certain of our existing stockholders) and proceeds before expenses to us.

The offering expenses payable by us, exclusive of the underwriting discounts and commissions, are approximately $350,000.

We have agreed to indemnify the several underwriters against certain liabilities, including liabilities under the Securities Act relating to losses or claims resulting from material misstatements in or omissions from this prospectus supplement, the registration statement of which this prospectus supplement is a part, certain free writing prospectuses that may be used in the offering and in any marketing materials used in connection with this offering and to contribute to payments the underwriters may be required to make in respect of those liabilities.

We have agreed that we will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the SEC a registration statement under the Securities Act relating to, any of shares of our common stock or securities convertible into or exchangeable or exercisable for any of our shares of common stock, or publicly disclose the intention to make any offer, sale, pledge, disposition or filing, without the prior written consent of Stifel, Nicolaus & Company, Incorporated and JMP Securities LLC for a period of 90 days after the date of this prospectus supplement, other than the resale registration statement that we initially filed on July 22, 2016 in connection with the closing of the second tranche of the March 2016 financing and subject to other specified limited exceptions.

Our officers and directors and certain of our stockholders have agreed, subject to specified limited exceptions, that they will not offer, sell, contract to sell, contract to purchase, pledge or otherwise dispose of, directly or indirectly, any of our shares of common stock or securities convertible into or exchangeable or exercisable for any of our shares of common stock, or enter into any swap, hedge or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of our common stock, whether any of these transactions are to be settled by delivery of shares of our common stock or other securities, in cash or otherwise, make any demand for or exercise any right with respect to the registration of our common stock or any security convertible into or exchangeable or exercisable for our common stock, or publicly disclose the intention to do any of the foregoing, without, in each case, the prior written consent of Stifel, Nicolaus & Company, Incorporated and JMP Securities LLC for a period of 90 days after the date of this prospectus supplement. These restrictions do not apply to shares purchased in this offering.

Shares of our common stock are listed on the NASDAQ Global Market under the trading symbol “ARGS.” We do not intend to list the warrants on the NASDAQ Global Market, any other national securities exchange or any

other nationally recognized trading system. initial offering, the offering price, concession or any other term of this offering may be changed.

Until the distribution of the shares is completed, SEC rules may limit underwriters and selling group members from bidding for and purchasing our common stock. However, the representatives may engage in transactions that stabilize the price of our common stock, such as bids or purchases to peg, fix or maintain that price.

In connection with this offering, the underwriters may purchase and sell our common stock in the open market. These transactions may include short sales, purchases on the open market to cover positions created by short sales and stabilizing transactions. Short sales involve the sale by the underwriters of a greater number of shares than they are required to purchase in this offering. Since the underwriters do not have an over-allotment option in this offering, the underwriters may only close out a short position by purchasing shares in the open market. A short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of our common stock in the open market after pricing that could adversely affect investors who purchase in this offering. Stabilizing transactions consist of various bids for or purchases of shares of our common stock made by the underwriters in the open market prior to the closing of this offering.

The underwriters may also impose a penalty bid. This occurs when a particular underwriter repays to the underwriters a portion of the underwriting discount received by it because the representative has repurchased shares sold by or for the account of such underwriter in stabilizing or short covering transactions.

Similar to other purchase transactions, the underwriters’ purchases to cover the syndicate short sales may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock may be higher than the price that might otherwise exist in the open market. The underwriters may conduct these transactions on NASDAQ, in the over-the-counter market or otherwise.

Neither we nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our common stock. In addition, neither we nor any of the underwriters make any representation that the representatives will engage in these transactions or that these transactions, once commenced, will not be discontinued without notice.

In connection with this offering, certain of the underwriters or securities dealers may distribute prospectuses by electronic means, such as e-mail. In addition, one or more of the underwriters may facilitate Internet distribution for this offering to certain of their Internet subscription customers. Any such underwriter may allocate a limited number of shares for sale to its online brokerage customers. An electronic prospectus is available on the Internet websites maintained by any such underwriter. Other than the prospectus in electronic format, the information on the websites of any such underwriter is not part of this prospectus supplement.

The underwriters and their respective affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. Certain of the underwriters and their affiliates have engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us or our affiliates. They have received, or may in the future receive, customary fees and commissions for these transactions.

In the ordinary course of their various business activities, the underwriters and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative

securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers, and such investment and securities activities may involve securities and/or instruments of the issuer. The underwriters and their respective affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a “Relevant Member State”) an offer to the public of any securities may not be made in that Relevant Member State, except that an offer to the public in that Relevant Member State of any securities may be made at any time under the following exemptions under the Prospectus Directive, if they have been implemented in that Relevant Member State:

For the purposes of this provision, the expression an “offer to the public” in relation to any securities in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any securities to be offered so as to enable an investor to decide to purchase any securities, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State, the expression “Prospectus Directive” means Directive 2003/71/EC (and amendments thereto, including the 2010 PD Amending Directive, to the extent implemented in the Relevant Member State), and includes any relevant implementing measure in the Relevant Member State, and the expression “2010 PD Amending Directive” means Directive 2010/73/EU.

The securities may be sold only to purchasers purchasing as principal that are both “accredited investors” as defined in National Instrument 45-106 Prospectus and Registration Exemptions and “permitted clients” as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the securities must be made in accordance with an exemption from the prospectus requirements and in compliance with the registration requirements of applicable securities laws.

The securities may not be offered or sold in Hong Kong by means of any document other than (i) in circumstances which do not constitute an offer to the public within the meaning of the Companies Ordinance (Cap. 32, Laws of Hong Kong), or (ii) to “professional investors” within the meaning of the Securities and Futures Ordinance (Cap. 571, Laws of Hong Kong) and any rules made thereunder, or (iii) in other circumstances which do not result in the document being a “prospectus” within the meaning of the Companies Ordinance (Cap. 32, Laws of Hong Kong) and no advertisement, invitation or document relating to the shares may be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public in Hong Kong (except if permitted to do so under the laws of Hong Kong) other than with respect to securities which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” within the meaning of the Securities and Futures Ordinance (Cap. 571, Laws of Hong Kong) and any rules made thereunder.

This document does not constitute a prospectus under the Israeli Securities Law, 5728-1968, or the Securities Law, and has not been filed with or approved by the Israel Securities Authority. In the State of Israel, this prospectus is being distributed only to, and is directed only at, and any offer of the securities and is directed only at (i) a limited number of persons in accordance with Section 15A(a)(1) of the Securities Law or (ii) investors listed in the first addendum, or the Addendum, to the Securities Law, consisting primarily of joint investment in trust funds, provident funds, insurance companies, banks, portfolio managers, investment advisors, members of the Tel Aviv Stock Exchange, underwriters, venture capital funds, entities with equity in excess of NIS 50 million and “qualified individuals”, each as defined in the Addendum (as it may be amended from time to time), collectively referred to as qualified investors (in each case purchasing for their own account or, where permitted under the Addendum, for the accounts of their clients who are investors listed in the Addendum). Qualified investors will be required to submit written confirmation that they fall within the scope of the Addendum.

This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the securities may not be circulated or distributed, nor may the securities be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the “SFA”), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275 of the SFA or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA, in each case subject to compliance with conditions set forth in the SFA.

Where the securities are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

shares, debentures and units of shares and debentures of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the securities pursuant to an offer made under Section 275 of the SFA except:

The securities may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange (the “SIX”) or on any other stock exchange or regulated trading facility in Switzerland. This document has been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this document nor any other offering or marketing material relating to the securities or the offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, or the securities have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of securities will not be supervised by, the Swiss Financial Market Supervisory Authority FINMA, and the offer of securities has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes (“CISA”). Accordingly, no public distribution, offering or advertising, as defined in CISA, its implementing ordinances and notices, and no distribution to any non-qualified investor, as defined in CISA, its implementing ordinances and notices, shall be undertaken in or from Switzerland, and the investor protection afforded to acquirers of interests in collective investment schemes under CISA does not extend to acquirers of securities.

The validity of the securities offered hereby is being passed upon for us by Wilmer Cutler Pickering Hale and Dorr LLP, Boston, Massachusetts. Goodwin Procter LLP, New York, New York is acting as counsel for the underwriters in connection with this offering.

The financial statements incorporated in this Prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2015 have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC’s website at http://www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at http://www.argostherapeutics.com. Our website is not a part of this prospectus supplement and is not incorporated by reference in this prospectus supplement. You may also read and copy any document we file at the SEC’s Public Reference Room, 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the Public Reference Room.

This prospectus supplement is part of a registration statement that we filed with the SEC. The registration statement contains more information than this prospectus supplement and the accompanying prospectus regarding us and the securities, including certain exhibits and schedules. You can obtain a copy of the registration statement from the SEC at the address listed above or from the SEC’s internet site.

The SEC allows us to incorporate by reference in this prospectus supplement and the accompanying prospectus much of the information we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus supplement and the accompanying prospectus are considered to be part of this prospectus supplement and the accompanying prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus supplement and the accompanying prospectus are continually updated and those future filings may modify or supersede some of the information included or incorporated in this prospectus supplement and the accompanying prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus supplement, the accompanying prospectus or in any document previously incorporated by reference have been modified or superseded. This prospectus supplement and the accompanying prospectus incorporate by reference the documents listed below (File No. 001-35443) and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, or the Exchange Act (in each case, other than those documents or the portions of those documents not deemed to be filed) until the offering of the securities under the registration statement is terminated or completed:

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address or phone number:

We may offer and sell securities from time to time in one or more offerings of up to $125,000,000 in aggregate offering price. This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these securities in supplements to this prospectus. The prospectus supplements also will describe the specific manner in which these securities will be offered and also may supplement, update or amend information contained in this prospectus. You should read this prospectus and any applicable prospectus supplement before you invest in any of our securities.

We may offer these securities in amounts, at prices and on terms determined at the time of offering. The securities may be sold directly to you, through agents, or through underwriters and dealers. If agents, underwriters or dealers are used to sell the securities, we will name them and describe their compensation in a prospectus supplement.

Investing in our securities involves risks. See “Risk Factors” included in any accompanying prospectus supplement, any related free writing prospectus, and in the documents incorporated by reference in this prospectus for a discussion of the factors you should carefully consider before deciding to purchase these securities.

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

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, which we refer to as the “SEC,” utilizing a “shelf” registration process. Under this shelf registration process, we may from time to time sell any combination of the securities described in this prospectus in one or more offerings for an aggregate initial offering price of up to $125,000,000.

This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide one or more prospectus supplements that will contain specific information about the terms of the offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and the accompanying prospectus supplement together with the additional information described under the heading “Where You Can Find More Information” beginning on page 2 of this prospectus.

You should rely only on the information contained in or incorporated by reference in this prospectus, any accompanying prospectus supplement or in any related free writing prospectus filed by us with the SEC. We have not authorized anyone to provide you with different information. This prospectus and any accompanying prospectus supplement do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus or such accompanying prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus, any prospectus supplement, the documents incorporated by reference and any related free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Unless the context otherwise indicates, references in this prospectus to “we,” “our” and “us” refer, collectively, to Argos Therapeutics, Inc. a Delaware corporation, and its consolidated subsidiary.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC’s website at http://www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at http://www.argostherapeutics.com. Our website is not a part of this prospectus and is not incorporated by reference in this prospectus. You may also read and copy any document we file at the SEC’s Public Reference Room, 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the Public Reference Room.

This prospectus is part of a registration statement we filed with the SEC. This prospectus omits some information contained in the registration statement in accordance with SEC rules and regulations. You should review the information and exhibits in the registration statement for further information about us and our consolidated subsidiaries and the securities we are offering. Statements in this prospectus concerning any document we filed as an exhibit to the registration statement or that we otherwise filed with the SEC are not intended to be comprehensive and are qualified by reference to these filings. You should review the complete document to evaluate these statements.

The SEC allows us to incorporate by reference much of the information we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus is considered to be part of this prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus is continually updated and those future filings may modify or supersede some of the information included or incorporated in this prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus or in any document previously incorporated by reference have been modified or superseded. This prospectus incorporates by reference the documents listed below (File No. 001-35443) and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, or the Exchange Act, (in each case, other than those documents or the portions of those documents not deemed to be filed) between the date of the initial registration statement and the effectiveness of the registration statement and following the effectiveness of the registration statement until the offering of the securities under the registration statement is terminated or completed. We incorporate by reference the documents listed below:

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address or telephone number:

This prospectus and the information incorporated by reference in this prospectus contain forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this prospectus and the information incorporated by reference in this prospectus, including statements regarding our strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward-looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

The forward-looking statements in this prospectus and the information incorporated by reference in this prospectus include, among other things, statements about:

You are cautioned that these forward-looking statements are only predictions and are subject to risks, uncertainties and assumptions that are referenced in the section of any accompanying prospectus supplement entitled “Risk Factors.” You should also carefully review the risk factors and cautionary statements described in the other documents we file from time to time with the SEC, specifically our most recent Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q and our Current Reports on Form 8-K. We undertake no obligation to revise or update any forward-looking statements, except to the extent required by law.

We are a biopharmaceutical company focused on the development and commercialization of fully personalized immunotherapies for the treatment of cancer based on our proprietary technology platform called Arcelis.

We are developing AGS-004, our second most advanced Arcelis-based product candidate, for the treatment of HIV. We have completed three clinical trials of AGS-004. These include phase 1 and phase 2 trials funded by government grants and a phase 2b trial that was funded in full by the National Institutes of Health and the National Institute of Allergy and Infectious Diseases under a $39.8 million agreement. In addition, we are supporting an investigator-initiated phase 2 clinical trial of AGS-004 in adult HIV patients that is being conducted to evaluate the use of AGS-004 in combination with a latency reversing drug for HIV eradication, and we plan to support a second investigator-initiated phase 2 clinical trial of AGS-004, to evaluate AGS-004 for long-term viral control in pediatric patients.

Our principal executive offices are located at 4233 Technology Drive, Durham, North Carolina 27704 and our telephone number is (919) 287-6300.

CONSOLIDATED RATIOS OF EARNINGS TO FIXED CHARGES AND RATIOS OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS

The following table sets forth our ratio of earnings to fixed charges and ratios of earnings to combined fixed charges and preferred stock dividends and our coverage deficiency for each of the periods indicated. You should read this table in conjunction with the consolidated financial statements and notes incorporated by reference in this prospectus.

We intend to use the net proceeds from the sale of any securities offered under this prospectus for general corporate purposes unless otherwise indicated in the applicable prospectus supplement. General corporate purposes may include the research and development of our product pipeline, acquisition of companies or businesses, repayment and refinancing of debt, working capital and capital expenditures. We have not determined the amount of net proceeds to be used specifically for such purposes. As a result, management will retain broad discretion over the allocation of net proceeds.

We may offer debt securities which may be senior or subordinated. We refer to the senior debt securities and the subordinated debt securities collectively as debt securities. The following description summarizes the general terms and provisions of the debt securities. We will describe the specific terms of the debt securities and the extent, if any, to which the general provisions summarized below apply to any series of debt securities in the prospectus supplement relating to the series and any applicable free writing prospectus that we authorize to be delivered. When we refer to “the Company,” “we,” “our,” and “us” in this section, we mean Argos Therapeutics, Inc. excluding, unless the context otherwise requires or as otherwise expressly stated, our subsidiaries.

We may issue senior debt securities from time to time, in one or more series under a senior indenture to be entered into between us and a senior trustee to be named in a prospectus supplement, which we refer to as the senior trustee. We may issue subordinated debt securities from time to time, in one or more series under a subordinated indenture to be entered into between us and a subordinated trustee to be named in a prospectus supplement, which we refer to as the subordinated trustee. The forms of senior indenture and subordinated indenture are filed as exhibits to the registration statement of which this prospectus forms a part. Together, the senior indenture and the subordinated indenture are referred to as the indentures and, together, the senior trustee and the subordinated trustee are referred to as the trustees. This prospectus briefly outlines some of the provisions of the indentures. The following summary of the material provisions of the indentures is qualified in its entirety by the provisions of the indentures, including definitions of certain terms used in the indentures. Wherever we refer to particular sections or defined terms of the indentures, those sections or defined terms are incorporated by reference in this prospectus or the applicable prospectus supplement. You should review the indentures that are filed as exhibits to the registration statement of which this prospectus forms a part for additional information.

None of the indentures will limit the amount of debt securities that we may issue. The applicable indenture will provide that debt securities may be issued up to an aggregate principal amount authorized from time to time by us and may be payable in any currency or currency unit designated by us or in amounts determined by reference to an index.

The senior debt securities will constitute our unsecured and unsubordinated general obligations and will rank pari passu with our other unsecured and unsubordinated obligations. The subordinated debt securities will constitute our unsecured and subordinated general obligations and will be junior in right of payment to our senior indebtedness (including senior debt securities), as described under the heading “—Certain Terms of the Subordinated Debt Securities—Subordination.” The debt securities will be structurally subordinated to all existing and future indebtedness and other liabilities of our subsidiaries unless such subsidiaries expressly guarantee such debt securities.

The debt securities will be our unsecured obligations. Any secured debt or other secured obligations will be effectively senior to the debt securities to the extent of the value of the assets securing such debt or other obligations.

The applicable prospectus supplement and/or free writing prospectus will include any additional or different terms of the debt securities of any series being offered, including the following terms:

When we refer to “principal” in this section with reference to the debt securities, we are also referring to “premium, if any.”

We may from time to time, without notice to or the consent of the holders of any series of debt securities, create and issue further debt securities of any such series ranking equally with the debt securities of such series in all respects (or in all respects other than (1) the payment of interest accruing prior to the issue date of such further debt securities or (2) the first payment of interest following the issue date of such further debt securities). Such further debt securities may be consolidated and form a single series with the debt securities of such series and have the same terms as to status, redemption or otherwise as the debt securities of such series.

You may present debt securities for exchange and you may present debt securities for transfer in the manner, at the places and subject to the restrictions set forth in the debt securities and the applicable prospectus supplement. We will provide you those services without charge, although you may have to pay any tax or other governmental charge payable in connection with any exchange or transfer, as set forth in the indenture.

Debt securities may bear interest at a fixed rate or a floating rate. Debt securities bearing no interest or interest at a rate that at the time of issuance is below the prevailing market rate (original issue discount securities) may be sold at a discount below their stated principal amount. U.S. federal income tax considerations applicable to any such discounted debt securities or to certain debt securities issued at par which are treated as having been issued at a discount for U.S. federal income tax purposes will be described in the applicable prospectus supplement.

We may issue debt securities with the principal amount payable on any principal payment date, or the amount of interest payable on any interest payment date, to be determined by reference to one or more currency exchange rates, securities or baskets of securities, commodity prices or indices. You may receive a payment of principal on any principal payment date, or a payment of interest on any interest payment date, that is greater than or less than the amount of principal or interest otherwise payable on such dates, depending on the value on such dates of the applicable currency, security or basket of securities, commodity or index. Information as to the methods for determining the amount of principal or interest payable on any date, the currencies, securities or baskets of securities, commodities or indices to which the amount payable on such date is linked and certain related tax considerations will be set forth in the applicable prospectus supplement.

Covenants. Unless we indicate otherwise in a prospectus supplement, the senior debt securities will not contain any financial or restrictive covenants, including covenants restricting either us or any of our subsidiaries from incurring, issuing, assuming or guaranteeing any indebtedness secured by a lien on any of our or our subsidiaries’ property or capital stock, or restricting either us or any of our subsidiaries from entering into sale and leaseback transactions.

Consolidation, Merger and Sale of Assets. Unless we indicate otherwise in a prospectus supplement, we may not consolidate with or merge into any other person, in a transaction in which we are not the surviving corporation, or convey, transfer or lease our properties and assets substantially as an entirety to any person, in either case, unless:

No Protection in the Event of a Change in Control. Unless we indicate otherwise in a prospectus supplement with respect to a particular series of senior debt securities, the senior debt securities will not contain any provisions that may afford holders of the senior debt securities protection in the event we have a change in control or in the event of a highly leveraged transaction (whether or not such transaction results in a change in control).

Events of Default. Unless we indicate otherwise in a prospectus supplement with respect to a particular series of senior debt securities, the following are events of default under the senior indenture for any series of senior debt securities:

The default by us under any other debt, including any other series of debt securities, is not a default under the senior indenture.

If an event of default other than an event of default specified in the fourth bullet point above occurs with respect to a series of senior debt securities and is continuing under the senior indenture, then, and in each such case, either the trustee or the holders of not less than 25% in aggregate principal amount of such series then outstanding under the senior indenture (each such series voting as a separate class) by written notice to us and to the trustee, if such notice is given by the holders, may, and the trustee at the request of such holders shall, declare the principal amount of and accrued interest on such series of senior debt securities to be immediately due and payable, and upon this declaration, the same shall become immediately due and payable.

If an event of default specified in the fourth bullet point above occurs and is continuing, the entire principal amount of and accrued interest on each series of senior debt securities then outstanding shall become immediately due and payable.

Unless otherwise specified in the prospectus supplement relating to a series of senior debt securities originally issued at a discount, the amount due upon acceleration shall include only the original issue price of the senior debt securities, the amount of original issue discount accrued to the date of acceleration and accrued interest, if any.

Upon certain conditions, declarations of acceleration may be rescinded and annulled and past defaults may be waived by the holders of a majority in aggregate principal amount of all the senior debt securities of such series affected by the default, each series voting as a separate class. Furthermore, subject to various provisions in the senior indenture, the holders of a majority in aggregate principal amount of a series of senior debt securities, by notice to the trustee, may waive an existing default or event of default with respect to such senior debt securities and its consequences, except a default in the payment of principal of or interest on such senior debt securities or in respect of a covenant or provision of the senior indenture which cannot be modified or amended without the consent of the holders of each such senior debt security. Upon any such waiver, such default shall cease to exist, and any event of default with respect to such senior debt securities shall be deemed to have been cured, for every purpose of the senior indenture; but no such waiver shall extend to any subsequent or other default or event of default or impair any right consequent thereto.

The holders of a majority in aggregate principal amount of a series of senior debt securities may direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to such senior debt securities. However, the trustee may refuse to follow any direction that conflicts with law or the senior indenture, that may involve the trustee in personal liability or that the trustee determines in good faith may be unduly prejudicial to the rights of holders of such series of senior debt securities not joining in the giving of such direction and may take any other action it deems proper that is not inconsistent with any such direction received from holders of such series of senior debt securities. A holder may not pursue any remedy with respect to the senior indenture or any series of senior debt securities unless:

These limitations, however, do not apply to the right of any holder of a senior debt security to receive payment of the principal of and interest on such senior debt security in accordance with the terms of such debt security, or to bring suit for the enforcement of any such payment in accordance with the terms of such debt security, on or after the due date for the senior debt securities, which right shall not be impaired or affected without the consent of the holder.

The senior indenture requires certain of our officers to certify, on or before a fixed date in each year in which any senior debt security is outstanding, as to their knowledge of our compliance with all covenants, agreements and conditions under the senior indenture.

Satisfaction and Discharge. We can satisfy and discharge our obligations to holders of any series of debt securities if:

Under current U.S. federal income tax law, the deposit and our legal release from the debt securities would be treated as though we took back your debt securities and gave you your share of the cash and debt securities or bonds deposited in trust. In that event, you could recognize gain or loss on the debt securities you give back to us. Purchasers of the debt securities should consult their own advisers with respect to the tax consequences to them of such deposit and discharge, including the applicability and effect of tax laws other than the U.S. federal income tax law.

Defeasance. Unless the applicable prospectus supplement provides otherwise, the following discussion of legal defeasance and discharge and covenant defeasance will apply to any series of debt securities issued under the indentures.

Legal Defeasance. We can legally release ourselves from any payment or other obligations on the debt securities of any series (called “legal defeasance”) if certain conditions are met, including the following:

If we accomplish legal defeasance, as described above, you would have to rely solely on the trust deposit for repayment of the debt securities. You could not look to us for repayment in the event of any shortfall.

Covenant Defeasance. Without any change of current U.S. federal tax law, we can make the same type of deposit described above and be released from some of the covenants in the debt securities (called “covenant defeasance”). In that event, you would lose the protection of those covenants but would gain the protection of having money and securities set aside in trust to repay the debt securities. In order to achieve covenant defeasance, we must do the following (among other things):

If we accomplish covenant defeasance, you could still look to us for repayment of the debt securities if there were a shortfall in the trust deposit. In fact, if one of the events of default occurred (such as our bankruptcy) and the debt securities become immediately due and payable, there may be such a shortfall. Depending on the events causing the default, you may not be able to obtain payment of the shortfall.

Modification and Waiver. We and the trustee may amend or supplement the senior indenture or the senior debt securities without the consent of any holder:

Other amendments and modifications of the senior indenture or the senior debt securities issued may be made, and our compliance with any provision of the senior indenture with respect to any series of senior debt securities may be waived, with the consent of the holders of a majority of the aggregate principal amount of the outstanding senior debt securities of all series affected by the amendment or modification (voting together as a single class); provided, however, that each affected holder must consent to any modification, amendment or waiver that:

It shall not be necessary for the holders to approve the particular form of any proposed amendment, supplement or waiver, but it shall be sufficient if the holders’ consent approves the substance thereof. After an amendment, supplement or waiver of the senior indenture in accordance with the provisions described in this section becomes effective, the trustee must give to the holders affected thereby certain notice briefly describing the amendment, supplement or waiver. Any failure by the trustee to give such notice, or any defect therein, shall not, however, in any way impair or affect the validity of any such amendment, supplemental indenture or waiver.

No Personal Liability of Incorporators, Stockholders, Officers, Directors. The senior indenture provides that no recourse shall be had under any obligation, covenant or agreement of ours in the senior indenture or any supplemental indenture, or in any of the senior debt securities or because of the creation of any indebtedness represented thereby, against any of our incorporators, stockholders, officers or directors, past, present or future, or of any predecessor or successor entity thereof under any law, statute or constitutional provision or by the enforcement of any assessment or by any legal or equitable proceeding or otherwise. Each holder, by accepting the senior debt securities, waives and releases all such liability.

Concerning the Trustee. The senior indenture provides that, except during the continuance of an event of default, the trustee will not be liable except for the performance of such duties as are specifically set forth in the senior indenture. If an event of default has occurred and is continuing, the trustee will exercise such rights and powers vested in it under the senior indenture and will use the same degree of care and skill in its exercise as a prudent person would exercise under the circumstances in the conduct of such person’s own affairs.

The senior indenture and the provisions of the Trust Indenture Act of 1939 incorporated by reference therein contain limitations on the rights of the trustee thereunder, should it become a creditor of ours or any of our subsidiaries, to obtain payment of claims in certain cases or to realize on certain property received by it in respect of any such claims, as security or otherwise. The trustee is permitted to engage in other transactions, provided that if it acquires any conflicting interest (as defined in the Trust Indenture Act), it must eliminate such conflict or resign.

We may have normal banking relationships with the senior trustee in the ordinary course of business.

Unclaimed Funds. All funds deposited with the trustee or any paying agent for the payment of principal, premium, interest or additional amounts in respect of the senior debt securities that remain unclaimed for two years after the date upon which such principal, premium or interest became due and payable will be repaid to us. Thereafter, any right of any holder of senior debt securities to such funds shall be enforceable only against us, and the trustee and paying agents will have no liability therefor.

Governing Law. The senior indenture and the senior debt securities will be governed by, and construed in accordance with, the internal laws of the State of New York.

Other than the terms of the subordinated indenture and subordinated debt securities relating to subordination or otherwise as described in the prospectus supplement relating to a particular series of subordinated debt securities, the terms of the subordinated indenture and subordinated debt securities are identical in all material respects to the terms of the senior indenture and senior debt securities.

Additional or different subordination terms may be specified in the prospectus supplement applicable to a particular series.

Subordination. The indebtedness evidenced by the subordinated debt securities is subordinate to the prior payment in full of all of our senior indebtedness, as defined in the subordinated indenture. During the continuance beyond any applicable grace period of any default in the payment of principal, premium, interest or any other payment due on any of our senior indebtedness, we may not make any payment of principal of or interest on the subordinated debt securities (except for certain sinking fund payments). In addition, upon any payment or distribution of our assets upon any dissolution, winding-up, liquidation or reorganization, the payment of the principal of and interest on the subordinated debt securities will be subordinated to the extent provided in the subordinated indenture in right of payment to the prior payment in full of all our senior indebtedness. Because of this subordination, if we dissolve or otherwise liquidate, holders of our subordinated debt securities may receive less, ratably, than holders of our senior indebtedness. The subordination provisions do not prevent the occurrence of an event of default under the subordinated indenture.

The term “senior indebtedness” of a person means with respect to such person the principal of, premium, if any, interest on, and any other payment due pursuant to any of the following, whether outstanding on the date of the subordinated indenture or incurred by that person in the future:

unless, in the case of any particular indebtedness, renewal, extension or refunding, the instrument creating or evidencing it or the assumption or guarantee relating to it expressly provides that such indebtedness, renewal, extension or refunding is not superior in right of payment to the subordinated debt securities. Our senior debt securities constitute senior indebtedness for purposes of the subordinated debt indenture.

The following description of our capital stock is intended as a summary only and therefore is not a complete description of our capital stock. This description is based upon, and is qualified by reference to, our certificate of incorporation, our by-laws and applicable provisions of Delaware corporate law. You should read our certificate of incorporation and by-laws, which are filed as exhibits to the registration statement of which this prospectus forms a part, for the provisions that are important to you.

Our authorized capital stock consists of 200,000,000 shares of common stock and 5,000,000 shares of preferred stock. As of March 31, 2015, 19,688,802 shares of common stock were outstanding and no shares of preferred stock were outstanding.

Annual Meeting. Annual meetings of our stockholders are held on the date designated in accordance with our by-laws. Written notice must be mailed to each stockholder entitled to vote not less than ten nor more than 60 days before the date of the meeting. The presence in person or by proxy of the holders of record of a majority of our issued and outstanding shares entitled to vote at such meeting constitutes a quorum for the transaction of business at meetings of the stockholders. Special meetings of the stockholders may be called for any purpose by the board of directors and shall be called by the chairman of the board or the secretary upon the written request, stating the purpose of such meeting, of the holders of a majority of the outstanding shares of all classes of capital stock entitled to vote at the meeting. Except as may be otherwise provided by applicable law, our restated certificate of incorporation or our by-laws, all elections shall be decided by a plurality, and all other questions shall be decided by a majority, of the votes cast by stockholders entitled to vote thereon at a duly held meeting of stockholders at which a quorum is present.

Voting Rights. Each holder of common stock is entitled to one vote for each share held on all matters to be voted upon by stockholders.

Dividends. The holders of common stock, after any preferences of holders of any preferred stock, are entitled to receive dividends when and if declared by the board of directors out of legally available funds.

Liquidation and Dissolution. If we are liquidated or dissolved, the holders of the common stock will be entitled to share in our assets available for distribution to stockholders in proportion to the amount of common stock they own. The amount available for common stockholders is calculated after payment of liabilities. Holders of any preferred stock will receive a preferential share of our assets before the holders of the common stock receive any assets.

The common stock does not have cumulative voting rights. Holders of shares of the common stock are not required to make additional capital contributions.

Transfer Agent and Registrar. Computershare Trust Company, N.A. is transfer agent and registrar for the common stock.

We are authorized to issue “blank check” preferred stock, which may be issued in one or more series upon authorization of our board of directors. Our board of directors is authorized to fix the designation of the series, the number of authorized shares of the series, dividend rights and terms, conversion rights, voting rights, redemption rights and terms, liquidation preferences and any other rights, powers, preferences and limitations applicable to each series of preferred stock. The authorized shares of our preferred stock are available for issuance without further action by our stockholders, unless such action is required by applicable law or the rules of any stock exchange on which our securities may be listed. If the approval of our stockholders is not required for the issuance of shares of our preferred stock, our board may determine not to seek stockholder approval. The specific terms of any series of preferred stock offered pursuant to this prospectus will be described in the prospectus supplement relating to that series of preferred stock.

A series of our preferred stock could, depending on the terms of such series, impede the completion of a merger, tender offer or other takeover attempt. Our board of directors will make any determination to issue preferred shares based upon its judgment as to the best interests of our stockholders. Our directors, in so acting, could issue preferred stock having terms that could discourage an acquisition attempt through which an acquirer may be able to change the composition of our board of directors, including a tender offer or other transaction that some, or a majority, of our stockholders might believe to be in their best interests or in which stockholders might receive a premium for their stock over the then-current market price of the stock.

The preferred stock has the terms described below unless otherwise provided in the prospectus supplement relating to a particular series of preferred stock. You should read the prospectus supplement relating to the particular series of preferred stock being offered for specific terms, including:

The preferred stock will, when issued, be fully paid and non-assessable. Unless otherwise specified in the prospectus supplement, each series of preferred stock will rank equally as to dividends and liquidation rights in all respects with each other series of preferred stock. The rights of holders of shares of each series of preferred stock will be subordinate to those of our general creditors.

As described under “Description of Depositary Shares,” we may, at our option, with respect to any series of preferred stock, elect to offer fractional interests in shares of preferred stock, and provide for the issuance of depositary receipts representing depositary shares, each of which will represent a fractional interest in a share of the series of preferred stock. The fractional interest will be specified in the prospectus supplement relating to a particular series of preferred stock.

Rank. Unless otherwise specified in the prospectus supplement, the preferred stock will, with respect to dividend rights and rights upon our liquidation, dissolution or winding up of our affairs, rank:

Dividends. Holders of the preferred stock of each series will be entitled to receive, when, as and if declared by our board of directors, cash dividends at such rates and on such dates described in the prospectus supplement. Different series of preferred stock may be entitled to dividends at different rates or based on different methods of calculation. The dividend rate may be fixed or variable or both. Dividends will be payable to the holders of record as they appear on our stock books on record dates fixed by our board of directors, as specified in the applicable prospectus supplement.

Dividends on any series of preferred stock may be cumulative or noncumulative, as described in the applicable prospectus supplement. If our board of directors does not declare a dividend payable on a dividend payment date on any series of noncumulative preferred stock, then the holders of that noncumulative preferred stock will have no right to receive a dividend for that dividend payment date, and we will have no obligation to pay the dividend accrued for that period, whether or not dividends on that series are declared payable on any future dividend payment dates. Dividends on any series of cumulative preferred stock will accrue from the date we initially issue shares of such series or such other date specified in the applicable prospectus supplement.

No dividends may be declared or paid or funds set apart for the payment of any dividends on any parity securities unless full dividends have been paid or set apart for payment on the preferred stock. If full dividends are not paid, the preferred stock will share dividends pro rata with the parity securities.

No dividends may be declared or paid or funds set apart for the payment of dividends on any junior securities unless full dividends for all dividend periods terminating on or prior to the date of the declaration or payment will have been paid or declared and a sum sufficient for the payment set apart for payment on the preferred stock.

Liquidation Preference. Upon any voluntary or involuntary liquidation, dissolution or winding up of our affairs, then, before we make any distribution or payment to the holders of any common stock or any other class or series of our capital stock ranking junior to the preferred stock in the distribution of assets upon any liquidation, dissolution or winding up of our affairs, the holders of each series of preferred stock shall be entitled to receive out of assets legally available for distribution to stockholders,

liquidating distributions in the amount of the liquidation preference per share set forth in the prospectus supplement, plus any accrued and unpaid dividends thereon. Such dividends will not include any accumulation in respect of unpaid noncumulative dividends for prior dividend periods. Unless otherwise specified in the prospectus supplement, after payment of the full amount of their liquidating distributions, the holders of preferred stock will have no right or claim to any of our remaining assets. Upon any such voluntary or involuntary liquidation, dissolution or winding up, if our available assets are insufficient to pay the amount of the liquidating distributions on all outstanding preferred stock and the corresponding amounts payable on all other classes or series of our capital stock ranking on parity with the preferred stock and all other such classes or series of shares of capital stock ranking on parity with the preferred stock in the distribution of assets, then the holders of the preferred stock and all other such classes or series of capital stock will share ratably in any such distribution of assets in proportion to the full liquidating distributions to which they would otherwise be entitled.

Upon any such liquidation, dissolution or winding up and if we have made liquidating distributions in full to all holders of preferred stock, we will distribute our remaining assets among the holders of any other classes or series of capital stock ranking junior to the preferred stock according to their respective rights and preferences and, in each case, according to their respective number of shares. For such purposes, our consolidation or merger with or into any other corporation, trust or entity, or the sale, lease or conveyance of all or substantially all of our property or assets will not be deemed to constitute a liquidation, dissolution or winding up of our affairs.

Redemption. If so provided in the applicable prospectus supplement, the preferred stock will be subject to mandatory redemption or redemption at our option, as a whole or in part, in each case upon the terms, at the times and at the redemption prices set forth in such prospectus supplement.

The prospectus supplement relating to a series of preferred stock that is subject to mandatory redemption will specify the number of shares of preferred stock that shall be redeemed by us in each year commencing after a date to be specified, at a redemption price per share to be specified, together with an amount equal to all accrued and unpaid dividends thereon to the date of redemption. Unless the shares have a cumulative dividend, such accrued dividends will not include any accumulation in respect of unpaid dividends for prior dividend periods. We may pay the redemption price in cash or other property, as specified in the applicable prospectus supplement. If the redemption price for preferred stock of any series is payable only from the net proceeds of the issuance of shares of our capital stock, the terms of such preferred stock may provide that, if no such shares of our capital stock shall have been issued or to the extent the net proceeds from any issuance are insufficient to pay in full the aggregate redemption price then due, such preferred stock shall automatically and mandatorily be converted into the applicable shares of our capital stock pursuant to conversion provisions specified in the applicable prospectus supplement. Notwithstanding the foregoing, we will not redeem any preferred stock of a series unless:

However, at any time we may purchase or acquire preferred stock of that series (1) pursuant to a purchase or exchange offer made on the same terms to holders of all outstanding preferred stock of such series or (2) by conversion into or exchange for shares of our capital stock ranking junior to the preferred stock of such series as to dividends and upon liquidation.

If fewer than all of the outstanding shares of preferred stock of any series are to be redeemed, we will determine the number of shares that may be redeemed pro rata from the holders of record of such shares in proportion to the number of such shares held or for which redemption is requested by such holder or by any other equitable manner that we determine. Such determination will reflect adjustments to avoid redemption of fractional shares.

Unless otherwise specified in the prospectus supplement, we will mail notice of redemption at least 30 days but not more than 60 days before the redemption date to each holder of record of preferred stock to be redeemed at the address shown on our stock transfer books. Each notice shall state:

If notice of redemption has been given and we have set aside the funds necessary for such redemption in trust for the benefit of the holders of any shares called for redemption, then from and after the redemption date, dividends will cease to accrue on such shares, and all rights of the holders of such shares will terminate, except the right to receive the redemption price.

Voting Rights. Holders of preferred stock will not have any voting rights, except as required by law or as indicated in the applicable prospectus supplement.

Unless otherwise provided for under the terms of any series of preferred stock, no consent or vote of the holders of shares of preferred stock or any series thereof shall be required for any amendment to our certificate of incorporation that would increase the number of authorized shares of preferred stock or the number of authorized shares of any series thereof or decrease the number of authorized shares of preferred stock or the number of authorized shares of any series thereof (but not below the number of authorized shares of preferred stock or such series, as the case may be, then outstanding).

Conversion Rights. The terms and conditions, if any, upon which any series of preferred stock is convertible into our common stock will be set forth in the applicable prospectus supplement relating thereto. Such terms will include the number of shares of common stock into which the shares of preferred stock are convertible, the conversion price, rate or manner of calculation thereof, the

conversion period, provisions as to whether conversion will be at our option or at the option of the holders of the preferred stock, the events requiring an adjustment of the conversion price and provisions affecting conversion in the event of the redemption.

Transfer Agent and Registrar. The transfer agent and registrar for the preferred stock will be set forth in the applicable prospectus supplement.

Provisions of Our Certificate of Incorporation and By-laws and Delaware Law That May Have Anti-Takeover Effects

Our certificate of incorporation and our bylaws divide our board of directors into three classes with staggered three-year terms. In addition, our certificate of incorporation and our bylaws provide that directors may be removed only for cause and only by the affirmative vote of the holders of 75% of our shares of capital stock present in person or by proxy and entitled to vote. Under our certificate of incorporation and bylaws, any vacancy on our board of directors, including a vacancy resulting from an enlargement of our board of directors, may be filled only by vote of a majority of our directors then in office. Furthermore, our certificate of incorporation provides that the authorized number of directors may be changed only by the resolution of our board of directors. The classification of our board of directors and the limitations on the ability of our stockholders to remove directors, change the authorized number of directors and fill vacancies could make it more difficult for a third party to acquire, or discourage a third party from seeking to acquire, control of our company.

The Delaware General Corporation Law, which we refer to as the DGCL, provides generally that the affirmative vote of a majority of the shares entitled to vote on any matter is required to amend a corporation’s certificate of incorporation or bylaws unless a corporation’s certificate of incorporation or bylaws, as the case may be, requires a greater percentage. Our bylaws may be amended or repealed by a majority vote of our board of directors or the affirmative vote of the holders of at least 75% of the votes that all our stockholders would be entitled to cast in any annual election of directors. In addition, the affirmative vote of the holders of at least 75% of the votes that all our stockholders would be entitled to cast in any election of directors is required to amend or repeal or to adopt any provisions inconsistent with any of the provisions of our certificate of incorporation described above.

Stockholder Action; Special Meeting of Stockholders; Advance Notice Requirements for Stockholder Proposals and Director Nominations

Our certificate of incorporation and our bylaws provide that any action required or permitted to be taken by our stockholders at an annual meeting or special meeting of stockholders may only be taken if it is properly brought before such meeting and may not be taken by written action in lieu of a meeting. Our certificate of incorporation and our bylaws also provide that, except as otherwise required by law, special meetings of the stockholders can only be called by the chairman of our board of directors, our chief executive officer or our board of directors. In addition, our bylaws establish an advance notice procedure for stockholder proposals to be brought before an annual meeting of stockholders, including proposed nominations of candidates for election to our board of directors. Stockholders at an annual meeting may only consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of our board of directors, or by a stockholder of record on the record date for the meeting who is entitled to vote at the meeting and who has delivered timely written notice in proper form to our secretary of the stockholder’s intention to bring such business before the meeting. These provisions could have the effect of delaying until the next stockholder meeting stockholder actions that are favored by the holders of a majority of our outstanding voting securities. These provisions also could discourage a third party from making a tender offer for our common stock, because even if the

third party acquired a majority of our outstanding voting stock, it would be able to take action as a stockholder, such as electing new directors or approving a merger, only at a duly called stockholders meeting and not by written consent.

Delaware Business Combination Statute. We are subject to Section 203 of the DGCL. Section 203 of the DGCL restricts some types of transactions and business combinations between a corporation and a 15% stockholder. A 15% stockholder is generally considered by Section 203 to be a person owning 15% or more of the corporation’s outstanding voting stock. Section 203 refers to a 15% stockholder as an “interested stockholder.” Section 203 restricts these transactions for a period of three years from the date the stockholder acquires 15% or more of our outstanding voting stock. With some exceptions, unless the transaction is approved by the board of directors and the holders of at least two-thirds of the outstanding voting stock of the corporation, Section 203 prohibits significant business transactions such as:

The shares held by the interested stockholder are not counted as outstanding when calculating the two-thirds of the outstanding voting stock needed for approval.

We may, at our option, elect to offer fractional shares of preferred stock, which we call depositary shares, rather than full shares of preferred stock. If we do, we will issue to the public receipts, called depositary receipts, for depositary shares, each of which will represent a fraction, to be described in the applicable prospectus supplement, of a share of a particular series of preferred stock. Unless otherwise provided in the prospectus supplement, each owner of a depositary share will be entitled, in proportion to the applicable fractional interest in a share of preferred stock represented by the depositary share, to all the rights and preferences of the preferred stock represented by the depositary share. Those rights include dividend, voting, redemption, conversion and liquidation rights.

The shares of preferred stock underlying the depositary shares will be deposited with a bank or trust company selected by us to act as depositary under a deposit agreement between us, the depositary and the holders of the depositary receipts. The depositary will be the transfer agent, registrar and dividend disbursing agent for the depositary shares.

The depositary shares will be evidenced by depositary receipts issued pursuant to the deposit agreement. Holders of depositary receipts agree to be bound by the deposit agreement, which requires holders to take certain actions such as filing proof of residence and paying certain charges.

The summary of terms of the depositary shares contained in this prospectus is not a complete description of the terms of the depository shares. You should refer to the form of the deposit agreement, our certificate of incorporation and the certificate of designation for the applicable series of preferred stock that are, or will be, filed with the SEC.

The depositary will distribute all cash dividends or other cash distributions, if any, received in respect of the preferred stock underlying the depositary shares to the record holders of depositary shares in proportion to the numbers of depositary shares owned by those holders on the relevant record date. The relevant record date for depositary shares will be the same date as the record date for the underlying preferred stock.

If there is a distribution other than in cash, the depositary will distribute property (including securities) received by it to the record holders of depositary shares, unless the depositary determines that it is not feasible to make the distribution. If this occurs, the depositary may, with our approval, adopt another method for the distribution, including selling the property and distributing the net proceeds from the sale to the holders.

If a series of preferred stock underlying the depositary shares has a liquidation preference, in the event of the voluntary or involuntary liquidation, dissolution or winding up of us, holders of depositary shares will be entitled to receive the fraction of the liquidation preference accorded each share of the applicable series of preferred stock, as set forth in the applicable prospectus supplement.

Unless the related depositary shares have been previously called for redemption, upon surrender of the depositary receipts at the office of the depositary, the holder of the depositary shares will be entitled to delivery, at the office of the depositary to or upon his or her order, of the number of whole shares of the preferred stock and any money or other property represented by the depositary shares. If the depositary

receipts delivered by the holder evidence a number of depositary shares in excess of the number of depositary shares representing the number of whole shares of preferred stock to be withdrawn, the depositary will deliver to the holder at the same time a new depositary receipt evidencing the excess number of depositary shares. In no event will the depositary deliver fractional shares of preferred stock upon surrender of depositary receipts. Holders of preferred stock thus withdrawn may not thereafter deposit those shares under the deposit agreement or receive depositary receipts evidencing depositary shares therefor.

Whenever we redeem shares of preferred stock held by the depositary, the depositary will redeem as of the same redemption date the number of depositary shares representing shares of the preferred stock so redeemed, so long as we have paid in full to the depositary the redemption price of the preferred stock to be redeemed plus an amount equal to any accumulated and unpaid dividends on the preferred stock to the date fixed for redemption. The redemption price per depositary share will be equal to the redemption price and any other amounts per share payable on the preferred stock multiplied by the fraction of a share of preferred stock represented by one depositary share. If less than all the depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or pro rata or by any other equitable method as may be determined by the depositary.

After the date fixed for redemption, depositary shares called for redemption will no longer be deemed to be outstanding and all rights of the holders of depositary shares will cease, except the right to receive the monies payable upon redemption and any money or other property to which the holders of the depositary shares were entitled upon redemption upon surrender to the depositary of the depositary receipts evidencing the depositary shares.

Upon receipt of notice of any meeting at which the holders of the preferred stock are entitled to vote, the depositary will mail the information contained in the notice of meeting to the record holders of the depositary receipts relating to that preferred stock. The record date for the depositary receipts relating to the preferred stock will be the same date as the record date for the preferred stock. Each record holder of the depositary shares on the record date will be entitled to instruct the depositary as to the exercise of the voting rights pertaining to the number of shares of preferred stock represented by that holder’s depositary shares. The depositary will endeavor, insofar as practicable, to vote the number of shares of preferred stock represented by the depositary shares in accordance with those instructions, and we will agree to take all action that may be deemed necessary by the depositary in order to enable the depositary to do so. The depositary will not vote any shares of preferred stock except to the extent it receives specific instructions from the holders of depositary shares representing that number of shares of preferred stock.

We will pay all transfer and other taxes and governmental charges arising solely from the existence of the depositary arrangements. We will pay charges of the depositary in connection with the initial deposit of the preferred stock and any redemption of the preferred stock. Holders of depositary receipts will pay transfer, income and other taxes and governmental charges and such other charges (including those in connection with the receipt and distribution of dividends, the sale or exercise of rights, the withdrawal of the preferred stock and the transferring, splitting or grouping of depositary receipts) as are expressly provided in the deposit agreement to be for their accounts. If these charges have not been paid by the holders of depositary receipts, the depositary may refuse to transfer depositary shares, withhold dividends and distributions and sell the depositary shares evidenced by the depositary receipt.

The form of depositary receipt evidencing the depositary shares and any provision of the deposit agreement may be amended by agreement between us and the depositary. However, any amendment that materially and adversely alters the rights of the holders of depositary shares, other than fee changes, will not be effective unless the amendment has been approved by the holders of a majority of the outstanding depositary shares. The deposit agreement may be terminated by the depositary or us only if:

The depositary may resign at any time by delivering to us notice of its election to do so, and we may remove the depositary at any time. Any resignation or removal of the depositary will take effect upon our appointment of a successor depositary and its acceptance of such appointment. The successor depositary must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company having its principal office in the United States and having the requisite combined capital and surplus as set forth in the applicable agreement.

The depositary will forward to holders of depositary receipts all notices, reports and other communications, including proxy solicitation materials received from us, that are delivered to the depositary and that we are required to furnish to the holders of the preferred stock. In addition, the depositary will make available for inspection by holders of depositary receipts at the principal office of the depositary, and at such other places as it may from time to time deem advisable, any reports and communications we deliver to the depositary as the holder of preferred stock.

Neither we nor the depositary will be liable if either we or it is prevented or delayed by law or any circumstance beyond its control in performing its obligations. Our obligations and those of the depositary will be limited to performance in good faith of our and their duties thereunder. We and the depositary will not be obligated to prosecute or defend any legal proceeding in respect of any depositary shares or preferred stock unless satisfactory indemnity is furnished. We and the depositary may rely upon written advice of counsel or accountants, on information provided by persons presenting preferred stock for deposit, holders of depositary receipts or other persons believed to be competent to give such information and on documents believed to be genuine and to have been signed or presented by the proper party or parties.

We may issue purchase contracts, including contracts obligating holders to purchase from or sell to us, and obligating us to sell to or purchase from the holders, a specified number of shares of our common stock, preferred stock or depositary shares at a future date or dates, which we refer to in this prospectus as purchase contracts. The price per share of common stock, preferred stock or depositary shares and the number of shares of each may be fixed at the time the purchase contracts are issued or may be determined by reference to a specific formula set forth in the purchase contracts. The purchase contracts may be issued separately or as part of units, often known as purchase units, consisting of one or more purchase contracts and beneficial interests in debt securities or any other securities described in the applicable prospectus supplement or any combination of the foregoing, securing the holders’ obligations to purchase the common stock, preferred stock or depositary shares under the purchase contracts.

The purchase contracts may require us to make periodic payments to the holders of the purchase units or vice versa, and these payments may be unsecured or prefunded on some basis. The purchase contracts may require holders to secure their obligations under those contracts in a specified manner, including pledging their interest in another purchase contract.

The applicable prospectus supplement will describe the terms of the purchase contracts and purchase units, including, if applicable, collateral or depositary arrangements.

We may issue warrants to purchase common stock, preferred stock, depositary shares or debt securities. We may offer warrants separately or together with one or more additional warrants, common stock, preferred stock, depositary shares or debt securities, or any combination of those securities in the form of units, as described in the applicable prospectus supplement. If we issue warrants as part of a unit, the accompanying prospectus supplement will specify whether those warrants may be separated from the other securities in the unit prior to the expiration date of the warrants. The applicable prospectus supplement will also describe the following terms of any warrants:

Each debt security, depositary share, purchase contract, purchase unit and warrant will be represented either by a certificate issued in definitive form to a particular investor or by one or more global securities representing the entire issuance of securities. Unless the applicable prospectus supplement provides otherwise, certificated securities in definitive form and global securities will be issued in registered form. Definitive securities name you or your nominee as the owner of the security, and in order to transfer or exchange these securities or to receive payments other than interest or other interim payments, you or your nominee must physically deliver the securities to the trustee, registrar, paying agent or other agent, as applicable. Global securities name a depositary or its nominee as the owner of the debt securities, depositary shares, purchase contracts, purchase units or warrants represented by these global securities. The depositary maintains a computerized system that will reflect each investor’s beneficial ownership of the securities through an account maintained by the investor with its broker/dealer, bank, trust company or other representative, as we explain more fully below.

We may issue the debt securities, depositary shares, purchase contracts, purchase units and warrants in the form of one or more fully registered global securities that will be deposited with a depositary or its nominee identified in the applicable prospectus supplement and registered in the name of that depositary or nominee. In those cases, one or more global securities will be issued in a denomination or aggregate denominations equal to the portion of the aggregate principal or face amount of the securities to be represented by global securities. Unless and until it is exchanged in whole for securities in definitive registered form, a global security may not be transferred except as a whole by and among the depositary for the global security, the nominees of the depositary or any successors of the depositary or those nominees.

If not described below, any specific terms of the depositary arrangement with respect to any securities to be represented by a global security will be described in the prospectus supplement relating to those securities. We anticipate that the following provisions will apply to all depositary arrangements.

Ownership of beneficial interests in a global security will be limited to persons, called participants, that have accounts with the depositary or persons that may hold interests through participants. Upon the issuance of a global security, the depositary will credit, on its book-entry registration and transfer system, the participants’ accounts with the respective principal or face amounts of the securities beneficially owned by the participants. Any dealers, underwriters or agents participating in the distribution of the securities will designate the accounts to be credited. Ownership of beneficial interests in a global security will be shown on, and the transfer of ownership interests will be effected only through, records maintained by the depositary, with respect to interests of participants, and on the records of participants, with respect to interests of persons holding through participants. The laws of some states may require that some purchasers of securities take physical delivery of these securities in definitive form. These laws may impair your ability to own, transfer or pledge beneficial interests in global securities.

So long as the depositary, or its nominee, is the registered owner of a global security, that depositary or its nominee, as the case may be, will be considered the sole owner or holder of the securities represented by the global security for all purposes under the applicable indenture, deposit agreement, purchase contract, warrant agreement or purchase unit agreement. Except as described below, owners of beneficial interests in a global security will not be entitled to have the securities represented by the global security registered in their names, will not receive or be entitled to receive physical delivery of the securities in definitive form and will not be considered the owners or holders of the securities under the applicable indenture, deposit agreement, purchase contract, purchase unit agreement or warrant agreement. Accordingly, each person owning a beneficial interest in a global security must rely on the procedures of

the depositary for that global security and, if that person is not a participant, on the procedures of the participant through which the person owns its interest, to exercise any rights of a holder under the applicable indenture, deposit agreement, purchase contract, purchase unit agreement or warrant agreement. We understand that under existing industry practices, if we request any action of holders or if an owner of a beneficial interest in a global security desires to give or take any action that a holder is entitled to give or take under the applicable indenture, deposit agreement, purchase contract, purchase unit agreement or warrant agreement, the depositary for the global security would authorize the participants holding the relevant beneficial interests to give or take that action, and the participants would authorize beneficial owners owning through them to give or take that action or would otherwise act upon the instructions of beneficial owners holding through them.

Principal, premium, if any, and interest payments on debt securities, and any payments to holders with respect to depositary shares, warrants, purchase agreements or purchase units, represented by a global security registered in the name of a depositary or its nominee will be made to the depositary or its nominee, as the case may be, as the registered owner of the global security. None of us, or any trustee, warrant agent, unit agent or other agent of ours, or any agent of any trustee, warrant agent or unit agent will have any responsibility or liability for any aspect of the records relating to payments made on account of beneficial ownership interests in the global security or for maintaining, supervising or reviewing any records relating to those beneficial ownership interests.

We expect that the depositary for any of the securities represented by a global security, upon receipt of any payment to holders of principal, premium, interest or other distribution of underlying securities or other property on that registered global security, will immediately credit participants’ accounts in amounts proportionate to their respective beneficial interests in that global security as shown on the records of the depositary. We also expect that payments by participants to owners of beneficial interests in a global security held through participants will be governed by standing customer instructions and customary practices, as is now the case with the securities held for the accounts of customers or registered in “street name,” and will be the responsibility of those participants.

If the depositary for any of the securities represented by a global security is at any time unwilling or unable to continue as depositary or ceases to be a clearing agency registered under the Exchange Act, and a successor depositary registered as a clearing agency under the Exchange Act is not appointed by us within 90 days, we will issue securities in definitive form in exchange for the global security that had been held by the depositary. Any securities issued in definitive form in exchange for a global security will be registered in the name or names that the depositary gives to the relevant trustee, warrant agent, unit agent or other relevant agent of ours or theirs. It is expected that the depositary’s instructions will be based upon directions received by the depositary from participants with respect to ownership of beneficial interests in the global security that had been held by the depositary.

In addition, we may issue the securities as a dividend or distribution or in a subscription rights offering to our existing security holders. This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement.

We may directly solicit offers to purchase securities, or agents may be designated to solicit such offers. We will, in the prospectus supplement relating to such offering, name any agent that could be viewed as an underwriter under the Securities Act, and describe any commissions that we must pay. Any such agent will be acting on a best efforts basis for the period of its appointment or, if indicated in the applicable prospectus supplement, on a firm commitment basis.

The distribution of the securities may be effected from time to time in one or more transactions:

Each prospectus supplement will describe the method of distribution of the securities and any applicable restrictions.

The prospectus supplement with respect to the securities of a particular series will describe the terms of the offering of the securities, including the following:

If any underwriters or agents are utilized in the sale of the securities in respect of which this prospectus is delivered, we will enter into an underwriting agreement or other agreement with them at the time of sale to them, and we will set forth in the prospectus supplement relating to such offering the names of the underwriters or agents and the terms of the related agreement with them.

If a dealer is utilized in the sale of the securities in respect of which this prospectus is delivered, we will sell such securities to the dealer, as principal. The dealer may then resell such securities to the public at varying prices to be determined by such dealer at the time of resale.

If we offer securities in a subscription rights offering to our existing security holders, we may enter into a standby underwriting agreement with dealers, acting as standby underwriters. We may pay the standby underwriters a commitment fee for the securities they commit to purchase on a standby basis. If we do not enter into a standby underwriting arrangement, we may retain a dealer-manager to manage a subscription rights offering for us.

Remarketing firms, agents, underwriters, dealers and other persons may be entitled under agreements which they may enter into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, and may be customers of, engage in transactions with or perform services for us in the ordinary course of business.

If so indicated in the applicable prospectus supplement, we will authorize underwriters or other persons acting as our agents to solicit offers by certain institutions to purchase securities from us pursuant to delayed delivery contracts providing for payment and delivery on the date stated in the prospectus supplement. Each contract will be for an amount not less than, and the aggregate amount of securities sold pursuant to such contracts shall not be less nor more than, the respective amounts stated in the prospectus supplement. Institutions with whom the contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions, but shall in all cases be subject to our approval. Delayed delivery contracts will not be subject to any conditions except that:

Certain agents, underwriters and dealers, and their associates and affiliates may be customers of, have borrowing relationships with, engage in other transactions with, and/or perform services, including investment banking services, for us or one or more of our respective affiliates in the ordinary course of business.

In order to facilitate the offering of the securities, any underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of the securities or any other securities the prices of which may be used to determine payments on such securities. Specifically, any underwriters may overallot in connection with the offering, creating a short position for their own accounts. In addition, to cover overallotments or to stabilize the price of the securities or of any such other securities, the underwriters may bid for, and purchase, the securities or any such other securities in the open market. Finally, in any offering of the securities through a syndicate of underwriters, the underwriting syndicate may reclaim selling concessions allowed to an underwriter or a dealer for distributing the securities in the offering if the syndicate repurchases previously distributed securities in transactions to cover syndicate short positions, in stabilization transactions or otherwise. Any of these activities may stabilize or maintain the market price of the securities above independent market levels. Any such underwriters are not required to engage in these activities and may end any of these activities at any time.

Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in three business days, unless the parties to any such trade expressly agree otherwise. The applicable prospectus supplement may provide that the original issue date for your securities may be more than three scheduled business days after the trade date for your securities. Accordingly, in such a case, if you wish to trade securities on any date prior to the third business day before the original issue date for your securities, you will be required, by virtue of the fact that your securities initially are expected to settle more than three scheduled business days after the trade date for your securities, to make alternative settlement arrangements to prevent a failed settlement.

The securities may be new issues of securities and may have no established trading market. The securities may or may not be listed on a national securities exchange. We can make no assurance as to the liquidity of or the existence of trading markets for any of the securities.

In compliance with the guidelines of the Financial Industry Regulatory Authority, or FINRA, the aggregate maximum discount, commission or agency fees or other items constituting underwriting compensation to be received by any FINRA member or independent broker-dealer will not exceed 8% of the proceeds from any offering pursuant to this prospectus and any applicable prospectus supplement.

Unless the applicable prospectus supplement indicates otherwise, the validity of the securities in respect of which this prospectus is being delivered will be passed upon by Wilmer Cutler Pickering Hale and Dorr LLP.

The financial statements incorporated in this Prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2014 have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.


	Per Share and Accompanying Warrant		Total
Public offering price	$	5.50	$	49,999,999.50
Underwriting discount on shares purchased by certain investors⁽¹⁾	$	0.00	$	0.00
Underwriting discount on shares purchased by other investors⁽²⁾	$	0.33	$	1,410,000.57
Proceeds to us before expenses⁽³⁾	$	5.34	$	48,589,998.93


ABOUT THIS PROSPECTUS SUPPLEMENT			S-i
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS			S-ii
PROSPECTUS SUPPLEMENT SUMMARY			S-1
RISK FACTORS			S-11
USE OF PROCEEDS			S-49
PRICE RANGE OF COMMON STOCK			S-51
DIVIDEND POLICY			S-52
CAPITALIZATION			S-53
DILUTION			S-54
DESCRIPTION OF THE SECURITIES WE ARE OFFERING			S-55
MATERIAL FEDERAL U.S. TAX CONSIDERATIONS			S-57
UNDERWRITING			S-63
LEGAL MATTERS			S-69
EXPERTS			S-69
WHERE YOU CAN FIND MORE INFORMATION			S-69
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE			S-70


ABOUT THIS PROSPECTUS			1
WHERE YOU CAN FIND MORE INFORMATION			2
INCORPORATION BY REFERENCE			2
FORWARD-LOOKING STATEMENTS			3
PROSPECTUS SUMMARY			5
CONSOLIDATED RATIOS OF EARNINGS TO FIXED CHARGES AND RATIOS OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS			6
USE OF PROCEEDS			7
DESCRIPTION OF DEBT SECURITIES			8
DESCRIPTION OF CAPITAL STOCK			17
DESCRIPTION OF DEPOSITARY SHARES			24
DESCRIPTION OF PURCHASE CONTRACTS AND PURCHASE UNITS			27
DESCRIPTION OF WARRANTS			28
FORMS OF SECURITIES			29
PLAN OF DISTRIBUTION			31
LEGAL MATTERS			34
EXPERTS			34


	High		Low
Year ended December 31, 2014
First Quarter (beginning February 7, 2014)	$	13.74	$	7.97
Second Quarter		10.55		6.21
Third Quarter		10.80		5.61
Fourth Quarter		10.28		7.80
Year ended December 31, 2015
First Quarter	$	10.56	$	6.36
Second Quarter		9.64		6.51
Third Quarter		6.98		4.11
Fourth Quarter		6.35		1.61
Year ended December 31, 2016
First Quarter	$	8.65	$	1.83
Second Quarter		13.97		4.75
Third Quarter (through July 27, 2016)		7.08		5.30


	As of March 31, 2016
	Actual			Pro Forma			Pro Forma as Adjusted
	(unaudited)			(unaudited)			(unaudited)
	(in thousands, except share data)
Cash, cash equivalents and short-term investments	$	13,844		$	43,669		$	91,909

Long-term portion of notes payable		29,434			29,434			29,434

Stockholders’ deficit
Common stock, $0.001 par value, 200,000,000 shares authorized, pro forma and pro forma as adjusted; 25,639,662 shares issued and outstanding, actual; 31,118,334 shares issued and outstanding, pro forma; 40,209,243 shares issued and outstanding, pro forma as adjusted		26			32			41
Additional paid-in capital		271,712			301,531			349,762
Accumulated other comprehensive (loss) income		(130	)		(130	)		(130	)
Accumulated deficit		(291,779	)		(291,779	)		(291,779	)

Total stockholders’ equity (deficit)		(20,171	)		9,654			57,894

Total capitalization	$	9,263		$	39,088		$	87,328


Public offering price per share				$	5.50
Historical net tangible book value per share as of March 31, 2016	$	(0.79	)
Pro forma increase in net tangible book value per share as of March 31, 2016 attributable to the issuance of shares of common stock and warrants to purchase common stock	$	1.10

Pro forma as adjusted net tangible book value per share as of March 31, 2016 before giving effect to this offering	$	0.31
Increase per share attributable to this offering	$	1.13

Pro forma as adjusted net tangible book value per share after this offering				$	1.44

Dilution per share to investors participating in this offering				$	4.06


Name	Number of Shares		Number of Shares Underlying Accompanying Warrants
Stifel, Nicolaus & Company, Incorporated		3,818,182		2,863,637
JMP Securities LLC		3,272,728		2,454,545
Needham & Company, LLC		1,272,727		954,545
FBR Capital Markets & Co.		363,636		272,727
Roth Capital Partners, LLC		363,636		272,727

Total		9,090,909		6,818,181


	Per Combined Share and Accompanying Warrant		Total
Public offering price	$	5.50	$	49,999,999.50
Underwriting discounts on sales to certain investors	$	0.00	$	0.00
Underwriting discounts on sales to other investors	$	0.33	$	1,410,000.57
Proceeds, before expenses, to us⁽¹⁾	$	5.34	$	48,589,998.93


	December 31, 2014			December 31, 2013			December 31, 2012			December 31, 2011
	(in millions)
Net loss⁽¹⁾	$	(53.3	)	$	(23.9	)	$	(10.5	)	$	(20.1	)
Consolidated ratios of earnings to fixed charges^(1)(2)(3)		N/A			N/A			N/A			N/A
Consolidated ratios of earnings to combined fixed charges and preferred stock dividends^(1)(2)(4)		N/A			N/A			N/A			N/A


Stifel		JMP Securities


FBR Capital Markets		Roth Capital Partners