As filed with the Securities and Exchange Commission on September 1, 2022

Registration No. 333-266846

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

AMENDMENT NO. 1

TO

FORM S-1

REGISTRATION STATEMENT

Under

The Securities Act of 1933

Apexigen, Inc.

(Exact name of Registrant as specified in its charter)

Delaware	2834	27-2989408
(State or other jurisdiction of incorporation or organization)	(Primary Standard Industrial Classification Code Number)	(I.R.S. Employer Identification Number)

75 Shoreway Road, Suite C

San Carlos, CA 94070

Telephone: (650) 931-6236

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Xiaodong Yang, M.D., Ph.D.

President and Chief Executive Officer

75 Shoreway Road, Suite C

San Carlos, CA 94070

Telephone: (650) 931-6236

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Kenneth A. Clark

Michael E. Coke

Lance E. Brady

Wilson Sonsini Goodrich & Rosati, P.C.

650 Page Mill Road

Palo Alto, CA 94304

Tel: (650) 493-9300

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.  ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer”, “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

If an emerging growth company, indicate by check mark if the Registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided to Section 7(a)(2)(B) of the Securities Act.  ☐

The Registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities, nor does it seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

PRELIMINARY PROSPECTUS Subject to Completion September 1, 2022

Primary Offering of

3,724,500 Shares of Common Stock Issuable Upon Exercise of Warrants

Secondary Offering of

14,434,863 Shares of Common Stock

849,500 Warrants to Purchase Shares of Common Stock

Apexigen, Inc.

This prospectus relates to the issuance by us of up to 3,724,500 shares of our Common Stock, par value $0.0001 per share (“Common Stock”) issuable upon the exercise of warrants, including (i) 2,875,000 shares issuable upon the exercise of an aggregate of 2,875,000 warrants, each of which is exercisable at a price of $11.50 per share held by the former public stockholders of Brookline Capital Acquisition Corp., a Delaware corporation, our predecessor (the “Public Warrants”), (ii) 726,000 shares issuable upon the exercise of an aggregate of 726,000 warrants, each of which is exercisable at a price of $11.50 per share held by the PIPE Investors (the “PIPE Warrants”), and (iii) 123,500 shares issuable upon the exercise of an aggregate of 123,500 warrants, each of which is exercisable at a price of $11.50 per share held by Brookline Capital Holdings, LLC (the “Private Placement Warrants”). The warrants were all purchased as a part of a unit that consisted of one share of our Common Stock and one-half of one warrant. The purchase price of each unit was $10.00 and the purchase price of each warrant was negligible.

In addition, this prospectus relates to the resale by the selling stockholders named in this prospectus (or their permitted transferees) (the “Selling Securityholders”) of up to (a) 14,434,863 shares of Common Stock, including (i) 8,009,884 shares held by certain former stockholders of Legacy Apexigen, including our officers and directors (the “Business Combination Shares”), which shares were purchased at a weighted average price of $10.40 per share, (ii) 1,452,000 shares held by the PIPE Investors (the “PIPE Shares”), which shares were purchased at a weighted average price of $10.00 per share, (iii) 1,248,479 shares held by Brookline Capital Holdings, LLC, together with our predecessor’s IPO underwriter and certain of its employees (the “Private Shares”), which shares were purchased at a weighted average price of $1.99 per share, (iv) 2,875,000 shares issuable upon the exercise of the Public Warrants, (v) 726,000 shares issuable upon the exercise of the PIPE Warrants, and (vi) 123,500 shares issuable upon the exercise of the Private Placement Warrants (collectively, the “Offered Shares”); and (b) 849,500 warrants, including (i) 726,000 PIPE Warrants and (ii) 123,500 Private Placement Warrants (collectively, the “Offered Warrants”).

The shares of Common Stock being offered for resale pursuant to this prospectus by the Selling Securityholders represent approximately 67.3% of shares outstanding as of August 30, 2022. Given the substantial number of shares of Common Stock being registered for potential resale by this prospectus, such sales, or the perception in the market that the Selling Securityholders intend to sell such shares, could increase the volatility of the market price of our Common Stock or result in a significant decline in the public trading price of our Common Stock.

The Selling Securityholders may sell any, all or none of the securities and we do not know when or in what amount the Selling Securityholders may sell their securities hereunder following the effective date of this registration statement. The Selling Securityholders may sell the securities described in this prospectus in a number of different ways and at varying prices. The Selling Securityholders will pay any underwriting discounts and commissions and expenses incurred by them in disposing of these securities. Even though our trading price is significantly below the price of our Common Stock at the time of the closing of the Business Combination, certain of the Selling Securityholders, including the holders of the Private Shares and certain of the former stockholders of Legacy Apexigen, may still have incentive to sell shares of Common Stock because they purchased the shares at prices lower than the current trading price of our Common Stock and may profit substantially even under circumstances in which our public stockholders may experience losses in connection with their investment as described further in the section titled, “Selling Securityholders” appearing elsewhere in this prospectus. We provide more information about how the Selling Securityholders may sell their securities in the section titled “Plan of Distribution” appearing elsewhere in this prospectus.

We will not receive any of the proceeds from such sales, but we will receive the proceeds from the exercise for cash of the warrants. We believe the likelihood that warrant holders will exercise their warrants, and therefore the amount of cash proceeds we would receive, is dependent upon the trading price of our Common Stock, the last reported sales price for which was $4.37 per share on August 30, 2022. If the trading price of our Common Stock is less than the $11.50 exercise price per share of the warrants, we expect that warrant holders will not exercise their warrants. We could receive up to an aggregate of approximately $42.8 million if all of the warrants are exercised for cash, but we will only receive such proceeds if and when the warrant holders exercise the warrants. There is no guarantee the warrants will be in the money following the time they become exercisable and prior to their expiration, and as such, the warrants may expire worthless and we may receive no proceeds from the exercise of warrants. To the extent that any of the warrants are exercised on a “cashless basis,” we will not receive any proceeds upon such exercise. We do not expect to rely on the cash exercise of warrants to fund our operations. Instead, we intend to rely on our primary sources of cash discussed elsewhere in this prospectus to continue to support our operations.

We will bear all costs, fees and expenses incurred in effecting the registration of these securities other than any underwriting discounts and commissions and expenses incurred by the Selling Securityholders, as described in more detail in the section titled “Use of Proceeds” appearing elsewhere in this prospectus.

The Private Shares, Business Combination Shares and shares issuable upon the exercise of the Private Placement Warrants are subject to lock-up restrictions applicable to the Selling Securityholders holding such securities as described herein.

Our Common Stock is traded on The Nasdaq Capital Market (“Nasdaq”) under the symbol “APGN.” Our public warrants are traded on Nasdaq under the symbol “APGNW.” On August 30, 2022, the last quoted sale price for our Common Stock as reported on Nasdaq was $4.37 per share and the last reported sale price of our warrants was $0.20 per warrant.

We are an “emerging growth company,” as defined under the federal securities laws, and, as such, may elect to comply with certain reduced public company reporting requirements for future filings.

Investing in our securities involves a high degree of risk. Before buying any securities, you should carefully read the discussion of the risks of investing in our securities in the section titled “Risk Factors” beginning on page 10 of this prospectus.

You should rely only on the information contained in this prospectus or any prospectus supplement or amendment hereto. We have not authorized anyone to provide you with different information.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is September     , 2022.

TABLE OF CONTENTS

	Page
Introductory Note		2
Glossary		3
Prospectus Summary		5
Risk Factors		10
Market, Industry and Other Data		67
Special Note Regarding Forward-Looking Statements		68
Unaudited Pro Forma Condensed Combined Financial Information		70
Use of Proceeds		82
Dividend Policy		83
Management’s Discussion and Analysis of Financial Condition and Results of Operations		84
Business		97
Management		135
Executive Compensation		144
Certain Relationships and Related Person Transactions		162
Selling Securityholders		166
Security Ownership of Certain Beneficial Owners and Management		172
Description of Securities		174
Plan of Distribution		183
Material U.S. Federal Income Tax Considerations		186
Legal Matters		193
Experts		193
Where You Can Find More Information		193
Index To Consolidated Financial Statements		F-1

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This prospectus is part of a registration statement on Form S-1 that we filed with the Securities and Exchange Commission (the “SEC”), which includes exhibits and provides more detail of the matters discussed in this prospectus. You should read this prospectus and the related exhibits filed with the SEC, together with the additional information described under the heading “Where You Can Find More Information” before making your investment decision. The Selling Securityholders may, from time to time, sell the securities offered by them described in this prospectus. We will not receive stockholder proceeds from the sale by such Selling Securityholders of the securities offered by them described in this prospectus.

Neither we nor the Selling Securityholders have authorized anyone to provide you with any information or to make any representations other than those contained in this prospectus or any applicable prospectus supplement or any free writing prospectuses prepared by or on behalf of us or to which we have referred you. Neither we nor the Selling Securityholders take responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. Neither we nor the Selling Securityholders will make an offer to sell these securities in any jurisdiction where the offer or sale is not permitted.

Except as otherwise set forth in this prospectus, neither we nor the Selling Securityholders have taken any action to permit a public offering of these securities outside the United States or to permit the possession or distribution of this prospectus outside the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about and observe any restrictions relating to the offering of these securities and the distribution of this prospectus outside the United States.

We may also provide a prospectus supplement or post-effective amendment to the registration statement to add information to, or update or change information contained in, this prospectus. You should read both this prospectus and any applicable prospectus supplement or post-effective amendment to the registration statement together with the additional information to which we refer you in the sections of this prospectus entitled “Where You Can Find More Information.”

We use our registered trademark and trade name, such as Apexigen®, in this prospectus. This prospectus may also include trademarks, trade names and service marks that are the property of other organizations. Solely for convenience, trademarks, trade names and service marks referred to in this prospectus may appear without the ® and ™ symbols, but those references are not intended to indicate that we will not assert, to the fullest extent under applicable law, our rights, or that the applicable owner will not assert its rights, to these trademarks, trade names and service marks. We do not intend our use or display of other entities’ trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of, any other entity.

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INTRODUCTORY NOTE

On July 29, 2022 (the “Closing Date”), Brookline Capital Acquisition Corp., a Delaware corporation (“BCAC”), Project Barolo Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of BCAC (“Merger Sub”) and Legacy Apexigen, consummated the previously announced Business Combination pursuant to the terms of the Business Combination Agreement (the “Closing”).

On the Closing Date, (i) BCAC changed its name to “Apexigen, Inc.” (“Apexigen” or the “Company”), (ii) Merger Sub merged with and into Legacy Apexigen (the “Merger”), with Legacy Apexigen surviving the Merger as a direct, wholly-owned subsidiary of the Company, (iii) the Company issued 1,452,000 shares of Common Stock to the PIPE Investors in exchange for $14,520,000 in consideration, (iv) the Company issued 150,000 shares of Common Stock to Lincoln Park pursuant to the terms of the Lincoln Park Purchase Agreement, and (v) the parties to the Business Combination Agreement consummated the other transactions contemplated thereby.

This prospectus relates to the issuance by us of up to 3,724,500 shares of Common Stock issuable upon the exercise of warrants (including (i) 2,875,000 shares issuable upon the exercise of the Public Warrants, (ii) 726,000 shares issuable upon the exercise of the PIPE Warrants, and (iii) 123,500 shares issuable upon the exercise of the Private Placement Warrants). In addition, this prospectus relates to the resale by the Selling Securityholders of up to (a) 14,434,863 shares of Common Stock (including (i) 8,009,884 Business Combination Shares, (ii) 1,452,000 PIPE Shares, (iii) 1,248,479 Private Shares, (iv) 2,875,000 shares issuable upon the exercise of the Public Warrants, (v) 726,000 shares issuable upon the exercise of the PIPE Warrants, and (vi) 123,500 shares issuable upon the exercise of the Private Placement Warrants) and (b) 849,500 warrants (including (i) 726,000 PIPE Warrants and (ii) 123,500 Private Placement Warrants).

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GLOSSARY

As used in this prospectus, unless otherwise noted or the context otherwise requires, references to:

“Amendment No. 1 to the Business Combination Agreement” are to that certain Amendment No. 1 to the Business Combination Agreement entered into as of June 26, 2022, by and among BCAC, Merger Sub and Legacy Apexigen;

“Apexigen” are to Apexigen, Inc., a Delaware corporation, following the Closing;

“Board” are to the board of directors of Apexigen;

“BCAC” are to Brookline Capital Acquisition Corp., a Delaware corporation, and legal predecessor of Apexigen;

“BCAC Common Stock” are to shares of common stock, par value $0.0001 per share, of BCAC prior to the Closing;

“BCAC Board” are to the board of directors of BCAC prior to the Closing;

“BCAC IPO” are to the initial public offering by BCAC, which closed on February 2, 2021;

“BCAC units” are to the units, comprised on one share of BCAC Common Stock and one-half of one redeemable BCAC warrant, issued at the closing of the BCAC IPO;

“BCAC warrants” are to all outstanding warrants of BCAC prior to the closing, each whole warrant of which entitled the holder to purchase one share of BCAC Common Stock at an exercise price of $11.50 per share;

“Business Combination” are to the Merger and the other transactions contemplated by the Business Combination Agreement and any other agreement executed and delivered in connection therewith;

“Business Combination Agreement” are to that certain Business Combination Agreement entered into on March 17, 2022, by and among BCAC, Merger Sub, and Legacy Apexigen (amended by Amendment No. 1 to the Business Combination Agreement and as it may be further amended, supplemented or otherwise modified from time to time in accordance with its terms), pursuant to which Merger Sub merged with and into Legacy Apexigen, with Legacy Apexigen surviving the Merger as a wholly owned subsidiary of BCAC;

“Code” are to the Internal Revenue Code of 1986, as amended;

“DGCL” are to the Delaware General Corporation Law, as may be amended from time to time;

“Exchange Act” are to the Securities Exchange Act of 1934, as amended;

“Extension Amendment” are to the amendment to the Amended and Restated Certificate of Incorporation of BCAC (“Existing Charter”) approved by BCAC’s stockholders on April 26, 2022 to extend the date by which BCAC must consummate a business combination transaction from May 2, 2022 (the date which is 15 months from the closing date of BCAC’s initial public offering of units) on a monthly basis up to November 2, 2022;

“GAAP” are to generally accepted accounting principles in the United States, as applied on a consistent basis;

“Legacy Apexigen” are to Apexigen, Inc., a Delaware corporation, prior to the Closing and Apexigen America, Inc., a Delaware Corporation, after the Closing;

“Legacy Apexigen Board” are to the board of directors of Legacy Apexigen prior to the Closing;

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“Legacy Apexigen capital stock” are to shares of common stock, par value $0.001 per share, and preferred stock, par value $0.001 per share, of Legacy Apexigen prior to the closing;

“Legacy Apexigen stockholders” are to the stockholders of Legacy Apexigen prior to the Closing;

“Nasdaq” are to The Nasdaq Capital Market;

“PIPE Investment” are to the purchase of an aggregate of 1,502,000 PIPE Units pursuant to subscription agreements BCAC entered into with certain investors in connection with the Business Combination Agreement (the “Subscription Agreements” and such investors, the “PIPE Investors”);

“PIPE Unit” are to each of the units, comprised of one share of BCAC Common Stock and one-half of one BCAC warrant (a “PIPE Warrant”), purchased by certain investors pursuant to the Subscription Agreements;

“Public Stockholders” are to the holders of shares of BCAC Common Stock sold as part of the BCAC units (whether they were purchase in the BCAC IPO or thereafter in the open market) (“Public Shares”) prior to the Closing, including the Sponsor and BCAC’s management team to the extent the Sponsor and/or members of BCAC’s management team purchased Public Shares in the open market, provided that the Sponsor’s and each member of BCAC’s management team’s status as a “public stockholder” only existed with respect to such Public Shares;

“Sponsor” are to Brookline Capital Holdings, LLC, a Delaware limited liability company;

“Supporting Apexigen Stockholders” are to certain stockholders of Legacy Apexigen who, in the aggregate, held

(a) at least a majority of the outstanding shares of Legacy Apexigen capital stock, voting together as a single class and

(b) at least a majority of the outstanding shares of Series A-1 Preferred Stock, Series B Preferred Stock and Series C Preferred Stock of Legacy Apexigen, voting together as a single class on an as-converted basis;

Unless specified otherwise, amounts in this prospectus are presented in United States (“U.S.”) dollars.

Defined terms in the financial statements contained in this prospectus have the meanings ascribed to them in the financial statements.

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PROSPECTUS SUMMARY

This summary highlights selected information appearing elsewhere in this prospectus and is qualified in its entirety by the more detailed information and financial statements included elsewhere in this prospectus. This summary may not contain all the information you should consider before investing in our Common Stock. You should carefully read this prospectus in its entirety before investing in our Common Stock, including the sections titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our financial statements and related notes included elsewhere in this prospectus. Unless the context otherwise requires, the term “Apexigen,” “the Company,” “our company,” “we,” “us,” and “our,” or other similar terminology, refer to Apexigen, Inc.

Corporate Overview

We are a clinical-stage biopharmaceutical company focused on discovering and developing a new generation of antibody therapeutics for oncology, with an emphasis on new immuno-oncology agents designed to harness the patient’s immune system to combat and eradicate cancer. We and our licensees are advancing several protein therapeutics that were discovered using our APXiMAB antibody platform. Our pipeline currently consists of our clinical-stage lead candidate, sotigalimab (“sotiga” or “APX005M”) and APX601. Further, five programs for the development of product candidates discovered with our APXiMAB platform have been licensed for further development. We are also advancing through discovery and preclinical development several innovative antibodies we discovered using our platform.

Our most advanced wholly owned product candidates are as follows:

• Sotigalimab is a humanized agonist antibody that targets and activates CD40, a co-stimulatory receptor that is essential for activating both the innate and adaptive arms of the immune system, to stimulate an anti-tumor immune response. Sotigalimab is currently in Phase 2 clinical development for the treatment of solid tumors such as melanoma, esophageal and gastroesophageal junction (“GEJ”) cancers, sarcoma, and ovarian cancers in combination with immunotherapy, chemotherapy, radiation therapy and cancer vaccines.

• APX601 is a humanized antagonist antibody that binds to TNFR2, which is highly expressed on immune suppressive cells, including Treg and suppressive myeloid cells, as well as on many cancers. We have largely completed preclinical studies of APX601 necessary for an investigational new drug application (“IND”).

Our APXiMAB platform was used to enable the discovery of multiple protein therapeutic product candidates against a variety of molecular targets, including targets that are difficult to drug with conventional antibody technologies. In addition to the product candidates that we wholly own, several product candidates discovered through the use of the APXiMAB platform are in clinical development by our licensees. The most advanced of these programs is Novartis’ Beovu® (brolucizumab-dbll) product, which received FDA approval in 2019 and is marketed in over 70 countries. Two other programs being developed by our licensees are in later-stage development; Simcere’s BD0801 is in Phase 3 clinical development in ovarian cancer and Mabwell’s 9MW0211 is in an adaptive, pivotal Phase 2/3 clinical trial in wet age-related macular degeneration (“AMD”). There is no guarantee that any of the product candidates discovered using our APXiMAB antibody platform, whether developed by us or our licensees, will receive regulatory approval.

Risk Factor Summary

Investing in our securities involves a high degree of risk. You should carefully consider the risks described below, as well as other information included in the sections titled “Management’s Discussion and Analysis of

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Financial Condition and Results of Operations” and “Risk Factors,” which may be relevant to decisions regarding an investment in or ownership of our securities. The occurrence of any of these risks could have a significant adverse effect on our reputation, business, financial condition, results of operations, growth and ability to accomplish our strategic objectives. We have organized the description of these risks into groupings in an effort to enhance readability, but many of the risks interrelate or could be grouped or ordered in other ways, so no special significance should be attributed to the groupings or order below. Such risks include, but are not limited to:

Risks related to our business and industry.

• We are in the early stages of clinical drug development and have a limited operating history and no products approved for commercial sale.

• We have incurred net losses since inception and expects to continue to incur significant net losses for the foreseeable future.

• We will require substantial additional capital to finance operations. If we are unable to raise such capital when needed or on acceptable terms, we may be forced to delay, reduce, and/or eliminate one or more research and drug development programs or future commercialization efforts.

• We are dependent on the success of our product candidates, including our lead product candidate, sotigalimab, which is currently in multiple clinical trials.

• Our clinical trials may reveal serious adverse events, toxicities, or other side effects of our current and any future product candidates that result in a safety profile that could inhibit regulatory approval or market acceptance of our product candidates.

• If we experience delays or difficulties in the enrollment of patients in clinical trials, our receipt of necessary marketing approvals could be delayed or prevented.

• The clinical trials of our current and any of our future product candidates may not demonstrate safety and efficacy to the satisfaction of regulatory authorities or otherwise be timely conducted or produce positive results.

• The regulatory approval processes of the Food and Drug Administration, European Medicines Agency, and comparable foreign regulatory authorities are lengthy, time-consuming, and inherently unpredictable. If we are ultimately unable to obtain regulatory approval for our product candidates, we will be unable to generate product revenue and our business will be substantially harmed.

• If we are unable to obtain, maintain, enforce, or protect our intellectual property rights in any products we develop or in our technology, if the scope of the intellectual property protection obtained is not sufficiently broad, or if we infringe the intellectual property rights of others, third parties could develop and commercialize products and technology similar or identical to those of Apexigen, we could be prevented from commercializing our products and we may not be able to compete effectively in our markets.

Corporate and Other Information

Our principal executive office is located at 75 Shoreway Road, Suite C, San Carlos, California 94070. Our telephone number is (650) 931-6236. Our corporate website address is www.apexigen.com. Information contained on, or that can be accessed through, our website is not incorporated by reference into this prospectus, and you should not consider information on our website to be part of this prospectus.

Implications of Being an Emerging Growth Company and a Smaller Reporting Company

We are an “emerging growth company,” as defined in Section 2(a) of the Securities Act, and we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies

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that are not emerging growth companies, including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404(b) of the Sarbanes-Oxley Act of 2002 (“Sarbanes-Oxley”), reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved.

Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. Under the JOBS Act, emerging growth companies can also delay adopting new or revised accounting standards until such time as those standards apply to private companies. We have elected to avail ourselves of this exemption from new or revised accounting standards and, therefore, will not be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies. As a result, the information we provide will be different than the information that is available with respect to other public companies that are not emerging growth companies. This may make it difficult or impossible to compare our financial results with the financial results of another public company that is either not an emerging growth company or is an emerging growth company that has chosen not to take advantage of the extended transition period exemptions because of the potential differences in accounting standards used.

We will remain an emerging growth company until the earlier of: (1) the last day of the fiscal year (a) following the fifth anniversary of the closing of BCAC’s initial public offering, (b) in which we have total annual gross revenue of at least $1.07 billion or (c) in which we qualify as a “large accelerated filer”, which, in addition to certain other criteria, means the market value of our common equity that is held by non-affiliates exceeds $700 million as of the end of the prior fiscal year’s second fiscal quarter or (2) the date on which we have issued more than $1 billion in non-convertible debt securities during the prior three-year period.

Additionally, we are a “smaller reporting company” as defined in Item 10(f)(1) of Regulation S-K. Smaller reporting companies may take advantage of certain reduced disclosure obligations, including, among other things, providing only two years of audited financial statements. We will remain a smaller reporting company until the last day of the fiscal year in which (i) the market value of our ordinary shares held by non-affiliates exceeds $250 million as of the prior June 30 or (ii) our annual revenue exceeded $100 million during such completed fiscal year and the market value of our ordinary shares held by non-affiliates exceeds $700 million as of the prior June 30.

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THE OFFERING

Issuer Apexigen, Inc.

Issuance of Common Stock

Shares of Common Stock issuable upon exercise of Warrants 3,724,500 shares of Common Stock (including (i) 2,875,000 shares issuable upon the exercise of the Public Warrants, (ii) 726,000 shares issuable upon the exercise of the PIPE Warrants, and (iii) 123,500 shares issuable upon the exercise of the Private Placement Warrants).

Exercise Price of the Warrants $11.50 per share, subject to adjustment as described herein.

Resale of Common Stock and Warrants

Common Stock offered by the Selling Securityholders 14,434,863 shares of Common Stock (including (i) 8,009,884 Business Combination Shares, (ii) 1,452,000 PIPE Shares, (iii) 1,248,479 Private Shares, (iv) 2,875,000 shares issuable upon the exercise of the Public Warrants, (v) 726,000 shares issuable upon the exercise of the PIPE Warrants, and (vi) 123,500 shares issuable upon the exercise of the Private Placement Warrants).

Warrants offered by the Selling Securityholders 849,500 warrants (including (i) 726,000 PIPE Warrants and (ii) 123,500 Private Placement Warrants).

Redemption The Warrants are redeemable in certain circumstances. See the section of this prospectus titled “Description of Securities” in this prospectus for further discussion.

Common Stock outstanding (as of July 29, 2022) 21,445,035

Use of Proceeds We will not receive any proceeds from the sale of the Offered Shares and the Offered Warrants by the Selling Securityholders (the “Securities”). We will receive up to an aggregate of approximately $42.8 million from the exercise of all Warrants, assuming the exercise in full of such Warrants for cash. We expect to use the net proceeds from the exercise of the Warrants for general corporate purposes. We believe the likelihood that warrant holders will exercise their warrants, and therefore the amount of cash proceeds we would receive, is dependent upon the trading price of our Common Stock, the last reported sale for which was $4.37 per share on August 30, 2022. As the trading price of our Common Stock is less than the $11.50 exercise price per share of the warrants, we expect that warrant holders will not exercise their warrants. See the section titled “Use of Proceeds” in this prospectus for more information.

Risk Factors See the section titled “Risk Factors” in this prospectus and other information included in this prospectus for a discussion of factors that you should consider carefully before deciding to invest in our Securities.

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Nasdaq Symbol “APGN” for our Common Stock.

“APGNW” for our Warrants.

Lock-Up Restrictions Certain of our stockholders are subject to a lock-up agreement that restricts, subject to certain exceptions, transfer of shares of our Common Stock or other securities exercisable, exchangeable or convertible into shares of Common Stock. See the section titled “Description of Securities” of this prospectus for more information.

Unless otherwise noted, the number of our shares of Common Stock outstanding is based on 21,445,035 shares of Common Stock outstanding as of July 29, 2022, and excludes:

• 3,415,868 shares of our Common Stock issuable upon the exercise of options assumed from Legacy Apexigen as a result of the Business Combination, with a weighted-average exercise price of $3.15 per share;

• 3,724,500 shares of our Common Stock issuable upon the exercise of warrants, each with an exercise price of $11.50 per share;

• 4,321 shares of our Common Stock issuable upon the exercise of a warrant assumed from Legacy Apexigen as a result of the Business Combination with an exercise price of $1.55 per share;

• 2,573,405 shares of our Common Stock reserved for future issuance under our 2022 Equity Incentive Plan (the “2022 Plan”);

• 257,341 shares of our Common Stock reserved for future issuance under our 2022 Employee Stock Purchase Plan (the “2022 ESPP”) and

• any additional shares that we may issue to Lincoln Park pursuant to the Lincoln Park Purchase Agreement should we elect to sell such shares to Lincoln Park.

Unless otherwise noted, the information in this prospectus assumes:

• no exercise of outstanding options or warrants subsequent to July 29, 2022.

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RISK FACTORS

An investment in our common stock involves risks. Prior to making a decision about investing in our common stock, you should consider carefully the risks together with all of the other information contained in this prospectus, including any risks described below. Each of the referenced risks and uncertainties could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities. Additional risks not known to us or that we believe are immaterial may also adversely affect our business, operating results and financial condition and the value of an investment in our securities. “Apexigen,” “the Company,” “we,” “us” or “our” refers to Legacy Apexigen prior to the consummation of the Business Combination and to Apexigen following the Business Combination.

Risks Related to Our Business, Financial Condition, and Need for Additional Capital

We are in the early stages of clinical drug development and have a limited operating history and no products approved for commercial sale, which may make it difficult for you to evaluate our current business and predict our future success and viability.

We are an early clinical-stage biopharmaceutical company with a limited operating history. Apexigen was incorporated and commenced operations in 2010 following a spin-out transaction from its parent company. We have no products approved for commercial sale and have not generated any revenue from commercial product sales. Our operations to date have been limited to performing research and development activities in support of our product development and licensing efforts, hiring personnel, raising capital to support and expand such activities, providing general and administrative support for these operations, developing potential product candidates, conducting preclinical studies and clinical trials, including clinical trials of sotigalimab, our lead product candidate, and our other wholly owned product candidates, and entering into, and performing our obligations under, licensing arrangements that have resulted in additional product candidates in clinical development or commercialization by our licensees. Other than sotigalimab, all of our wholly owned programs are in preclinical or research development. We have not yet demonstrated our ability to successfully complete any large-scale pivotal clinical trials, obtain marketing approvals, manufacture a drug on a commercial scale or arrange for a third party to do so on our behalf, or conduct sales and marketing activities. In addition, only one of our licensees has obtained marketing approvals for product candidates we have out-licensed. As a result, it may be more difficult for you to accurately predict our future success or viability than it could be if we had a longer operating history.

In addition, as a business with a limited operating history, we may encounter unforeseen expenses, difficulties, complications, delays, and other known and unknown factors and risks frequently experienced by early-stage biopharmaceutical companies in rapidly evolving fields. We also would need to transition from a company with a research and development focus to a company capable of supporting commercial activities after approval of any of our product candidates. We have not yet demonstrated an ability to successfully overcome such risks and difficulties, or to make such a transition. If we do not adequately address these risks and difficulties or successfully make such a transition, our business will suffer.

We have incurred net losses since inception and expect to continue to incur significant net losses for the foreseeable future.

Apexigen has incurred net losses since inception, has not generated any significant revenue to date, and has financed its operations prior to the Business Combination primarily through the issuance of convertible preferred stock, proceeds from collaborative research and development and out-license agreements, and borrowings under a debt arrangement. Apexigen’s net loss was $24.1 million and $28.9 million for the years ended December 31, 2020 and 2021, respectively. Apexigen’s net losses were $7.0 million and $8.1 million for the three months ended June 30, 2021 and 2022, respectively, and $13.5 million and $17.1 million for the six months ended June 30, 2021 and 2022, respectively.

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As of June 30, 2022, Apexigen had an accumulated deficit of $161.9 million. Apexigen has devoted substantially all of its resources and efforts to date to research and development. Our clinical-stage pipeline currently consists of multiple product candidates, including our lead product candidate, sotigalimab, and our other internal programs are in preclinical or research development. As a result, we expect that it will be several years, if ever, before we generate revenue from product sales. Even if we succeed in receiving marketing approval for and commercializing one or more of our product candidates, we expect that we will continue to incur substantial research and development and other expenses in order to develop and market additional potential products. In addition, for certain of our licensees from whom we are entitled to receive royalty payments if they successfully develop and commercialize any products covered by licenses we have with them, there is no guarantee that their product development and commercialization will lead to any such payments even if any such product candidates receive regulatory approval for commercial sale, including Beovu® (brolucizumab-dbll), which is commercialized by Novartis, for which Apexigen has received sales-based royalties that are currently fully constrained and recorded as deferred revenue on Apexigen’s balance sheet, as discussed below.

In connection with the Closing, we raised approximately $19.0 million of gross proceeds. We incurred approximately $8.9 million in transaction costs relating to the Business Combination, consisting of banking, legal, and other professional fees. The total net cash proceeds to us were approximately $9.2 million after we paid off the Extension and Working Capital Notes totaled $0.9 million.

Our financial statements for the year ended December 31, 2021 and for the three and six months ended June 30, 2022, included elsewhere in this prospectus have been prepared assuming we will continue as a going concern. As a development stage company, we expect to incur significant and increasing losses until regulatory approval is granted for sotigalimab, our lead product candidate. Regulatory approval is not guaranteed and may never be obtained. As a result, these conditions raise substantial doubt about our ability to continue as a going concern.

We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. The net losses we incur may fluctuate significantly from quarter-to-quarter such that a period-to-period comparison of our results of operations may not be a good indication of our future performance. The size of our future net losses will depend, in part, on the rate of future growth of our expenses and our ability to generate revenue. Our expected future losses will continue to have an adverse effect on our working capital and our ability to achieve and maintain profitability.

Our ability to generate revenue and achieve profitability depends significantly on our ability to achieve a number of objectives.

Our business depends entirely on the successful development and commercialization of our product candidates. Apexigen currently generates no revenue from commercial sales of any products. Apexigen has no products approved for commercial sale and we do not anticipate generating any revenue from product sales unless and until sometime after we have successfully completed clinical development and received marketing approval for the commercial sale of a product candidate, if ever. In addition, we may not receive significant amounts of royalty revenue, if any, from our licensees for their product candidates if and when such candidates receive regulatory approval for commercial sale and are commercialized, including Beovu, which is commercialized by Novartis, for which Apexigen has received sales-based royalties that are currently fully constrained and recorded as deferred revenue on Apexigen’s balance sheet as discussed below. Our ability to generate revenue and achieve profitability depends significantly on our ability to achieve a number of objectives, including:

• successful and timely completion of preclinical and clinical development of current and any future product candidates;

• timely receipt of marketing approvals from applicable regulatory authorities for current and any future product candidates for which we successfully complete clinical development;

• the extent of any required post-marketing approval commitments to applicable regulatory authorities;

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• developing an efficient and scalable manufacturing process for current and any future product candidates, including establishing and maintaining commercially viable supply and manufacturing relationships with third parties to obtain finished products that are appropriately packaged for sale;

• successful launch of commercial sales following any marketing approval, including the development of a commercial infrastructure, whether in-house or with one or more partners or collaborators;

• a continued acceptable safety profile following any marketing approval;

• commercial acceptance of current and any future product candidates as viable treatment options by patients, the medical community, and third-party payors;

• addressing any competing technological and market developments;

• identifying, assessing, acquiring, and developing new product candidates;

• obtaining and maintaining patent protection, regulatory exclusivity, and other intellectual property-related protection, both in the United States and internationally;

• enforcing and defending our rights in our intellectual property portfolio, including our licensed intellectual property;

• negotiating favorable terms in any partnership, collaboration, licensing, or other arrangements that may be necessary to develop, manufacture, or commercialize our product candidates; and

• attracting, hiring, and retaining qualified personnel.

We may never be successful in achieving our objectives and, even if we do, may never generate revenue that is significant or large enough to achieve profitability. If we do achieve profitability, we may not sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would decrease the value of our company and could impair our ability to maintain or further our research and development efforts, raise additional necessary capital, grow our business, and/or continue our operations.

We will require substantial additional capital to finance our operations. If we are unable to raise such capital when needed, or on acceptable terms, we may be forced to delay, reduce, and/or eliminate one or more of our research and drug development programs or future commercialization efforts.

Developing pharmaceutical products, including conducting preclinical studies and clinical trials, is a very time-consuming, expensive, and uncertain process that takes years to complete. We expect our expenses to increase in connection with our ongoing activities, particularly as we conduct clinical trials of, and seek marketing approval for sotigalimab and our other product candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to drug sales, marketing, manufacturing, and distribution. We also expect to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in order to maintain our continuing operations. If we are unable to raise capital when needed or on acceptable terms, we may be forced to delay, reduce, and/or eliminate one or more of our research and drug development programs or future commercialization efforts. Changing circumstances, some of which may be beyond our control, could cause us to consume capital significantly faster than we currently anticipate, and we may need to seek additional funds sooner than planned.

We plan to continue to use our cash on hand to fund our development of our product candidates and for other research and development activities, working capital, and other general corporate purposes. This may include additional research, hiring additional personnel, capital expenditures, and the costs of operating as a public company. Advancing the development of our current and any future product candidates will require a significant amount of capital. Our current cash and cash equivalents are not sufficient to fund all of the actions that are necessary to complete the development of sotigalimab or any of our other product candidates. We will be

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required to obtain further funding through public or private equity offerings, sale of shares of our common stock through utilization of our equity line with Lincoln Park, debt financings, partnership, collaborations, and licensing arrangements or other sources, which may dilute our stockholders or restrict our operating activities. In addition, there are certain conditions and limitations on our ability to utilize our $50,000,000 equity line with Lincoln Park. We will be required to satisfy various conditions in order to be able to commence purchases by Lincoln Park under the equity line. Once such conditions are satisfied, the Lincoln Park equity line purchases are subject to volume limitations tied to periodic market prices, ownership limitations limiting Lincoln Park from owning more than 4.99% of our common stock, a minimum closing price of $3.00 per share of common stock at which we can deliver a Regular Purchase notice to Lincoln Park to purchase shares of common stock, and other limitations as specified in the Lincoln Park Purchase Agreement. If any of these conditions are not satisfied or limitations are in effect, we may not be able to utilize all or part of the Lincoln Park equity line, which would have an adverse impact on our ability to satisfy our capital needs and could materially adversely impact our business. Adequate additional financing may not be available to us on acceptable terms, or at all. Our failure to raise capital as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy.

Risks Related to the Discovery, Development, and Commercialization of Our Product Candidates

We are dependent on the success of our product candidates, including our lead product candidate, sotigalimab, which is currently in multiple clinical trials. If we are unable to obtain approval for and commercialize our product candidates for one or more indications in a timely manner, our business will be materially harmed.

Our success is dependent on our ability to timely complete clinical trials and obtain marketing approval for, and then successfully commercialize, our product candidates, including our lead product candidate, sotigalimab, for one or more indications. Our product candidates are in the early stages of development and we are investing the majority of our efforts and financial resources in the research and development of sotigalimab for multiple indications, both directly through our own efforts and indirectly through clinical collaboration arrangements, including investigator- and cooperative group-sponsored trials (“ISTs”). Our product candidates will require additional clinical development, preclinical and manufacturing activities, marketing approval from government regulators, substantial investment, and significant marketing efforts before we generate any revenue from product sales. We are not permitted to market or promote any product candidates, in a jurisdiction before receiving marketing approval from the relevant regulatory authority, including, for example, the Food and Drug Administration (“FDA”) for marketing in the United States and the European Medicines Agency (“EMA”) for marketing in the European Union, and we may never receive such marketing approvals.

• The success of our product candidates will depend on numerous factors, including the following:

• successful and timely completion of our ongoing clinical trials;

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

• efficacy, safety and tolerability profiles that are satisfactory to the FDA, EMA or any comparable foreign regulatory authority for marketing approval;

• raising additional funds necessary to complete the clinical development of and to commercialize of our product candidates;

• timely receipt of marketing approvals for our product candidates from applicable regulatory authorities;

• the extent of any required post-marketing approval commitments to applicable regulatory authorities;

• the maintenance of existing or the establishment of new supply arrangements with third-party drug product suppliers and manufacturers;

• the maintenance of existing or the establishment of new scaled production arrangements with third-party manufacturers to obtain finished products that are appropriately packaged for sale;

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

• protection of our rights in our intellectual property portfolio, including our licensed intellectual property;

• successful launch of commercial sales following any marketing approval;

• a continued acceptable safety profile following any marketing approval;

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

• our ability to compete with other therapies.

We do not have complete control over many of these factors, including certain aspects of clinical development and the regulatory submission process, including trial design, implementation, and timely provision of data in our collaboration based clinical trials and ISTs; potential threats to our intellectual property rights; and the manufacturing, marketing, distribution, and sales efforts of any future collaborator. If we are unable to achieve one or more of the objectives set forth above, our business will be materially harmed.

Our clinical trials may reveal serious adverse events, toxicities, or other side effects of our current and any future product candidates that result in a safety profile that could inhibit regulatory approval or market acceptance of our product candidates.

In order to obtain marketing approval for our current or any future product candidates, we must demonstrate the safety and efficacy of the product candidate for the relevant clinical indication or indications through preclinical studies and clinical trials as well as additional supporting data. If our product candidates are associated with undesirable side effects in preclinical studies or clinical trials, or have unexpected characteristics, we may need to interrupt, delay, or abandon their development or limit development to more narrow 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.

Although we have conducted various preclinical studies and have data from various early-stage clinical trials, we do not know the predictive value of these studies and trials for our future clinical trials, and we cannot guarantee that any positive results in preclinical studies or previous clinical trials will successfully translate to patients in our future clinical trials. It is not uncommon to observe results in clinical trials that are unexpected based on preclinical testing or previous clinical trials, and many product candidates fail in clinical trials despite promising preclinical or early-stage clinical results. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval for their products.

While we believe that sotigalimab has been reasonably well tolerated in our clinical trials, subjects have experienced adverse events that have been considered treatment-related. Some of the more common adverse events included fever, chills, fatigue, asthenia, nausea, vomiting, pruritus, abnormal liver function/gamma gamma-glutamyl transferase/alkaline phosphatase tests, decreased appetite, rash, headache, diarrhea, infusion-related reactions, and cytokine release syndrome (“CRS”). The majority of these events were mild/moderate in severity, responded to symptomatic treatment and/or were transient and resolved with time.

Serious, including sometimes fatal, adverse events (“SAEs”) have been reported in clinical studies with sotigalimab. The majority of these SAEs were considered unrelated to sotigalimab by the investigators. Some SAEs were considered at least possibly related to sotigalimab as well as possibly to other therapies it was combined with.

These possibly related events have included infusion-related reactions, CRS, elevated liver enzymes, bilirubin, fever, and colitis. Less frequent related SAEs reported in one patient each have included kidney injury, hepatic

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failure, bleeding, immune-mediated encephalitis, myositis, optic neuritis. Many of these SAEs were also considered possibly related to the chemotherapy, radiation or anti-PD(L)1 agent that were used in combination or were assessed as not related to sotigalimab after a safety review by the trial sponsor.

Subjects experienced numerous other SAEs that have been determined to be caused by their health condition or the side effects from other components of the treatment regimens, and not or unlikely related to sotigalimab. Given the high mortality rates of the cancers for which we are initially pursuing development, in particular melanoma, esophageal and gastroesophageal junction (“GEJ”) cancers, sarcoma, and ovarian cancer, and the pretreated nature of many patients in our completed, ongoing and planned clinical trials of sotigalimab, a number of these subjects have died as a result of their cancer or from direct side effects of surgery and other treatment regimens for their cancer. For example, in our clinical trial for esophageal and GEJ cancers, sotigalimab is combined with standard of care neoadjuvant chemotherapy, radiation and surgery. These standard of care treatments alone are associated with significant toxicities including fatal outcomes, and in this study, complications of surgery have resulted in the death of a patient.

We expect that subjects in our ongoing and planned clinical trials for our product candidates may in the future suffer adverse effects (“AEs”), SAEs or other side effects, including those not observed in our preclinical studies or previous clinical trials. Results of these trials could reveal a high and unacceptable severity and prevalence of side effects or unexpected characteristics. Undesirable side effects caused by our product candidates could result in the delay, suspension, or termination of clinical trials by us or the FDA, EMA or comparable foreign regulatory authority for a number of reasons. Additionally, a number of the subjects in these clinical trials are expected to die during a trial due to the cancers they suffer and any of the treatment regimens they may have previously experienced, which could impact the development of our product candidates. If we elect or are required to delay, suspend, or terminate any clinical trial, the commercial prospects of our product candidates will be harmed and our ability to generate product revenue from this product candidate will be delayed or eliminated. SAEs observed in clinical trials could hinder or prevent market acceptance of our drug candidates. Any of these occurrences may harm our business, prospects, financial condition, and results of operations significantly.

Even in circumstances in which we do not believe that an AE is related to our product candidates, the investigation into the circumstances of such AE may be time-consuming or inconclusive. In particular, patients may face serious medical issues associated with the underlying cancer indications that our product candidates target, as well as AEs from toxicities and other complications related to other study drugs administered alongside or in combination with our product candidates in clinical trials. For example, some of our clinical trials involve combination therapies of our product candidate with other cancer therapies, such as standard-of-care chemotherapy, chemoradiation or anti-PD-(L)1 agents. In these trials, it is difficult to ascertain whether treatment-related AEs are attributable to our product candidates or to the other agents, and the combination of therapies may have a complicating multiplier effect on such AEs that cannot be determined. As a result, while not directly associated with our product candidates, there are attendant risks with the space in which our product candidates operate, and any related investigations may interrupt our development and commercialization efforts, delay our regulatory approval process or impact and limit the type of regulatory approvals our product candidates receive or maintain.

If further SAEs or other side effects are observed in any of our current or future clinical trials, we may have difficulty recruiting patients to the clinical trials, patients may discontinue treatment or withdraw from our trials or we may be required to abandon the trials or our development efforts of that product candidate altogether. We, the FDA, the EMA, other applicable regulatory authorities or an Institutional Review Board (“IRB”)/Ethics Committee may suspend clinical trials of a product candidate at any time for various reasons, including a belief that subjects in such trials are being exposed to unacceptable health risks or adverse side effects. Some potential therapeutics developed in the biotechnology industry that initially showed therapeutic promise in early-stage studies have later been found to cause side effects that prevented their further development. Even if the side effects do not preclude a drug from obtaining or maintaining marketing approval, undesirable side effects may

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inhibit market acceptance of the approved product due to its tolerability versus other therapies. Any of these developments could materially harm our business, financial condition, and prospects.

Further, if any of our product candidates obtains marketing approval, toxicities associated with our product candidates may also develop after such approval and lead to a requirement to conduct additional clinical safety trials, additional warnings being added to the labeling, significant restrictions on the use of the product, or the withdrawal of the product from the market. We cannot predict whether our product candidates will cause toxicities in humans that would preclude or lead to the revocation of regulatory approval based on preclinical studies or early-stage clinical testing.

If we experience delays or difficulties in the enrollment of patients in clinical trials, our receipt of necessary marketing approvals could be delayed or prevented.

We may not initiate, continue or complete 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, EMA, or comparable foreign regulatory authorities.

Patient enrollment is a significant factor in the timing of clinical trials, and our ability to enroll eligible patients may be limited or may result in slower enrollment than we anticipate. Patient enrollment may also be affected by other factors, including:

• size and nature of the patient population;

• severity of the disease under investigation;

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

• patient eligibility criteria for the trial in question;

• efforts to facilitate timely enrollment in clinical trials;

• patient referral practices of physicians;

• clinicians’ and patients’ awareness of, and perceptions as to the potential advantages and risks of, our product candidates in relation to other available therapies, including any new drugs that may be approved for the indications we are investigating;

• the ability to monitor patients adequately during and after treatment;

• competing ongoing clinical trials for the same indications as our product candidates;

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

• whether we become subject to a partial or full clinical hold on any of our clinical trials; and

• continued enrollment of prospective patients by clinical trial sites, including delays due to pandemics, wars etc. that can impact patient willingness to participate and travel for investigative therapy and reductions in clinical trial site staff and services.

Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays or may require us to abandon one or more of our clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our product candidates and jeopardize our ability to obtain marketing approval for the sale of our product candidates.

The clinical trials of our current and any future product candidates may not demonstrate safety and efficacy to the satisfaction of regulatory authorities or otherwise be timely conducted or produce positive results.

Before obtaining marketing approval from regulatory authorities for the sale of our product candidates, we must complete preclinical development and then conduct extensive clinical trials to demonstrate the safety and

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efficacy of our product candidates. Clinical testing is expensive, difficult to design and implement, can take many years to complete, and its ultimate outcome is uncertain. A failure of one or more clinical trials can occur at any stage of the process. The outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later clinical trials. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their drugs. In addition, in our clinical trials of sotigalimab that are in combination with other available therapies, the results may be uncertain as to the efficacy of the sotigalimab combination when compared to the efficacy of other therapies that are being applied in the trial.

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

• obtaining regulatory approval to commence a trial;

• delays in reaching, or the inability to reach, agreement on acceptable terms with prospective contract research organizations (“CROs”), clinical trial sites, laboratory service providers, companion diagnostic development partners, contract manufacturing organizations, or CMOs, and other service providers we may engage to support the conduct of our clinical trials;

• obtaining IRB approval at each clinical trial site;

• recruiting a sufficient number of suitable patients to participate in a trial;

• patients failing to comply with trial protocol or dropping out of a trial, rendering them not evaluable for study endpoints;

• clinical trial sites deviating from trial protocol or dropping out of a trial;

• the availability of any applicable combination therapies;

• developments in the safety and efficacy of any applicable combination therapies;

• the need to add new clinical trial sites; or

• delays in the testing, validation and manufacturing of product candidates and the delivery of these product candidates to clinical trial sites.

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

• receipt of feedback from regulatory authorities that requires us to modify the design of our clinical trials;

• negative or inconclusive clinical trial results that may require us to conduct additional clinical trials or abandon certain drug development programs;

• regulators or IRBs may not authorize us, our collaborators, or our investigators to commence a clinical trial or to conduct a clinical trial at a prospective site;

• the number of patients required for clinical trials being larger than anticipated, enrollment in these clinical trials being slower than anticipated, or participants dropping out of these clinical trials at a higher rate than anticipated;

• third-party contractors failing to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

• the suspension or termination of our clinical trials for various reasons, including non-compliance with regulatory requirements, a finding that our product candidates have undesirable side effects, safety or efficacy concerns, or any particular combination therapy or other unexpected characteristics or risks;

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• the cost of clinical trials of our product candidates being greater than anticipated;

• for clinical trials testing combination treatment of our product candidates with third-party drug products, delays in procuring such third-party drug products and the delivery of such third-party drug products to clinical trial sites, or the inability to procure such third-party drug products at all; and

• regulators revising the requirements for approving our product candidates, including as a result of newly approved agents changing the standard of care of an indication.

Any unforeseen events may cause us to be required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, or to be unable to successfully complete clinical trials of our product candidates or other testing. Clinical trial or test results may also not be positive or may be only modestly positive or may have safety concerns. For example, in the APX005M-002 Trial, we enrolled 95 patients with non-small cell lung cancer (“NSCLC”) who were either immunotherapy naïve or who had progressed while on anti-PD(L)1 therapy and treated those patients with sotigalimab in combination with nivolumab. Although we observed a modest number of objective responses in immunotherapy naïve patients and stable disease in patients who had previously progressed on or were refractory to prior anti-PD-(L)1 therapy, the data did not support advancing the development of sotigalimab in these lines of therapy in patients with NSCLC. Any of the foregoing events may cause us to incur unplanned costs, be delayed in obtaining marketing approval, if ever, receive more limited or restrictive marketing approval, be subject to additional post-marketing testing requirements, or have the drug removed from the market after obtaining marketing approval.

The outcome of preclinical testing and early clinical trials that we obtain and that we publish may not be predictive of the success of later clinical trials, and the results of our clinical trials may not satisfy the requirements of the FDA, EMA, or comparable foreign regulatory authorities.

We currently have no products approved for sale and we cannot guarantee that we will ever have marketable drugs. Clinical failure can occur at any stage of clinical development. Clinical trials may produce negative or inconclusive results, and we or any future collaborators may decide, or regulators may require us, to conduct additional clinical trials or preclinical studies. We will be required to demonstrate with substantial evidence through well-controlled clinical trials that our product candidates are safe and effective for use in a diverse population before we can seek marketing approvals for their commercial sale. Success in preclinical studies and early-stage clinical trials does not mean that future larger registration clinical trials will be successful. This is because product candidates in later-stage clinical trials may fail to demonstrate sufficient safety and efficacy to the satisfaction of the FDA, EMA, and other regulatory authorities despite having progressed through preclinical studies and early-stage clinical trials. In particular, no compound with the mechanism of action of sotigalimab has been commercialized, and the outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later-stage clinical trials. We do not know whether any clinical trials we may conduct will demonstrate consistent or adequate efficacy and safety results sufficient to obtain marketing approval to market our product candidates.

Summary or preliminary data from our clinical trials that we announce or publish may change as new or revised patient data becomes available, and is subject to source verification procedures that could result in material changes in the final data.

As more patient data becomes available, we may publicly disclose new or revised preliminary data from our clinical trials. These preliminary updates are based on analyses of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study or trial. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, the summary or preliminary results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Summary or preliminary data also remain subject to source verification procedures that may

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result in the final data being materially different from the summary or preliminary data we previously published. As a result, summary or preliminary data should be viewed with caution until the final data are available. In addition, we may report interim analyses of only certain endpoints rather than all endpoints. Preliminary data from clinical trials that we conduct may not be indicative of the final results of the trials and are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Adverse changes between preliminary data and final data could significantly harm our business and prospects. Further, additional disclosure of preliminary data by us or by our competitors in the future could result in volatility in the price of our common stock.

Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate, and our company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is typically selected from a more extensive amount of available information. Interested parties may not agree with what we determine is the material or otherwise appropriate information to include in our disclosure, and any information we determine not to disclose may ultimately be deemed significant with respect to future decisions, conclusions, views, activities, or otherwise regarding a particular product candidate or our business. If the preliminary or topline data that we report differ from late, final or actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed, which could harm our business, financial condition, results of operations, and prospects.

In some instances, there can be significant variability in safety and efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in trial protocols, differences in size and type of the patient populations, differences in and adherence to the dosing regimen and other trial protocols, use in combination with other therapies, and the rate of discontinuations by clinical trial participants. In addition, we may use patient-reported outcome assessments in some of our clinical trials, which involve patients’ subjective assessments of efficacy of the treatments they receive in the trial. Such assessments can vary widely from day to day for a particular patient, and from patient to patient and site to site within a clinical trial. This subjectivity can increase the uncertainty of, and adversely impact, our clinical trial outcomes.

Our product candidates may not achieve adequate market acceptance among physicians, patients, healthcare payors, and others in the medical community necessary for commercial success.

Even if our product candidates receive regulatory approval, they may not gain adequate market acceptance among physicians, patients, healthcare payors, and others in the medical community. For example, current standard-of-care cancer treatments, such as existing chemotherapy and radiation therapy, are well established in the medical community, and doctors may continue to rely on these treatments. The degree of market acceptance of any of our approved product candidates, if approved for commercial sale, will depend on a number of factors, including:

• the efficacy and safety profile as demonstrated in clinical trials;

• the timing of market introduction of the product candidate as well as competitive products;

• the approval of other new therapies for the same indications;

• the clinical indications for which the product candidate is approved;

• restrictions on the use of our products, if approved, such as boxed warnings, contraindications in labeling, or restrictions on use of our products together with other medications, or a risk evaluation and mitigation strategy (“REMS”), if any, which may not be required of alternative treatments and competitor products;

• the potential and perceived advantages of product candidates over alternative treatments or in combination therapies;

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• the cost of treatment in relation to alternative treatments;

• the availability of coverage and adequate reimbursement and pricing by third parties and government authorities;

• relative convenience and ease of administration;

• the effectiveness of sales and marketing efforts;

• the willingness of the target population to try new therapies and of physicians to prescribe these therapies; and

• unfavorable publicity relating to the product candidate.

If any product candidate is approved but does not achieve an adequate level of acceptance by physicians, hospitals, healthcare payors, and patients, we may generate less revenue from that product candidate than anticipated, which could harm our financial results.

The sizes of the patient populations suffering from some of the diseases we are targeting may be based on estimates that are inaccurate, may be small, or may be smaller than estimated.

We rely on estimates to project the incidence and prevalence of diseases we are targeting and the subset of patients with these diseases who have the potential to benefit from treatment with sotigalimab and our other product candidates. We derive these estimates from a variety of sources, including United States and global cancer databases, scientific literature, surveys of clinics, physician interviews, patient foundations, and market research, and they may prove to be incorrect. Further, new studies may change the estimated incidence or prevalence of these diseases. The number of patients may turn out to be lower than expected. Additionally, the potentially addressable patient population for sotigalimab and any other future product candidates may be more limited than we originally estimated or may not be amenable to treatment with sotigalimab and any other product candidates, if and when approved. For example, in March 2022, the FDA approved nivolumab and relatlimab-rmbw (OpdualagTM) for use in patients with unresectable or metastatic melanoma, which may limit the number of patients with unresectable or metastatic melanoma that have progressive disease during treatment with anti-PD-(L)1 therapy, which would be the target population for a potential registration-enabling study of sotigalimab in combination with a PD-(L)1 inhibitor that we are considering. Even if we obtain significant market share for sotigalimab and any other product candidates, small potential target populations for certain indications means we may never achieve profitability without obtaining market approval for additional indications.

Many of our additional internal programs, including APX601, are at earlier stages of development than sotigalimab and may fail in development or suffer delays, including if we are unable to raise adequate additional funding, that adversely affect their commercial viability.

Other than sotigalimab, all of our internal programs are in preclinical development or at the research stage and may fail in development or suffer delays that adversely affect their commercial viability. These programs may fail to yield product candidates. A product candidate can unexpectedly fail at any stage of preclinical and clinical development. The historical failure rate for product candidates is high due to risks relating to safety, efficacy, clinical execution, changing standards of medical care, and other unpredictable variables. The results from preclinical testing or early clinical trials of a product candidate may not be predictive of the results that will be obtained in later-stage clinical trials of the product candidate. The success of any product candidates we may develop will depend on many factors, including the following:

• generating sufficient data to support the initiation or continuation of clinical trials;

• obtaining regulatory permission to initiate clinical trials;

• contracting with the necessary parties to conduct clinical trials;

• the successful enrollment of patients in, and the completion of, clinical trials;

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• the timely manufacture of sufficient quantities of the product candidate, and any combination therapy, for use in clinical trials; and

• acceptable adverse profile in the clinical trials.

We will need additional funding to continue to advance the development of our other internal programs, including APX601. If we are unable to secure adequate funding to continue such development, we expect that we will be required to delay or stop the development of such programs.

Even if we successfully advance any other product candidates into clinical development, their success will be subject to all of the clinical, regulatory and commercial risks described elsewhere in this “Risk Factors” section. Accordingly, we cannot assure you that we will ever develop, obtain regulatory approval of, commercialize, or generate significant revenue from any product candidate.

Any product candidates we develop may become subject to unfavorable third-party reimbursement practices and pricing regulations.

The availability and extent of coverage and adequate reimbursement by governmental and private payors is essential for most patients to afford the expense of antibody therapeutics like sotigalimab and our other product candidates. Sales of any of our product candidates that receive marketing approval will depend substantially, both in the United States and internationally, on the extent to which the costs of our product candidates will be paid by health maintenance, managed care, pharmacy benefit, and similar healthcare management organizations or reimbursed by government health administration authorities, private health coverage insurers, and other third-party payors. If reimbursement is not available, or is available only to limited levels, we may not successfully commercialize our product candidates. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize an adequate return on our investment. Coverage and reimbursement may impact the demand for, or the price of, any product candidate for which we obtain marketing approval. If coverage and reimbursement are not available or reimbursement is available only to limited levels, we may not successfully commercialize any product candidate for which we obtain marketing approval.

There is significant uncertainty related to insurance coverage and reimbursement of newly approved products. In the United States, principal decisions about reimbursement for new products are typically made by Centers for Medicare & Medicaid Services (“CMS”), an agency within the U.S. Department of Health and Human Services (“HHS”). CMS decides whether and to what extent a new product will be covered and reimbursed under Medicare, and private payors often follow CMS’s decisions regarding coverage and reimbursement to a substantial degree. However, one payor’s determination to provide coverage for a drug product does not assure that other payors will also provide coverage for the drug product. As a result, the coverage determination process is often time-consuming and costly. This process will require us to provide scientific and clinical support for the use of our products to each payor separately, with no assurance that coverage and adequate reimbursement will be applied consistently or obtained in the first instance.

Increasingly, third-party payors require that drug companies provide them with predetermined discounts from list prices and challenge the prices charged for medical products. Further, such payors increasingly challenge the price, examine the medical necessity and review the cost effectiveness of medical drug products. There may be especially significant delays in obtaining coverage and reimbursement for newly approved drugs.

Third-party payors may limit coverage to specific drug products on an approved list, known as a formulary, which might not include all FDA-approved drugs for a particular indication. We may need to conduct expensive studies to demonstrate the medical necessity and cost-effectiveness of our products. Nonetheless, our product candidates may not be considered medically necessary or cost effective. We cannot be sure that coverage and reimbursement will be available for any product that we commercialize and, if reimbursement is available, what the level of reimbursement will be.

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Outside the United States, international operations are generally subject to extensive governmental price controls and other market regulations, and we believe the increasing emphasis on cost-containment initiatives in Europe, Canada and other countries has and will continue to put pressure on the pricing and usage of therapeutics such as our product candidates. In many countries, particularly the countries of the European Union, medical product prices are subject to varying price control mechanisms as part of national health systems. In these countries, pricing negotiations with governmental authorities can take considerable time after a product receives marketing approval. To obtain reimbursement or pricing approval in some countries, we may be required to conduct a clinical trial that compares the cost-effectiveness of our product candidate to other available therapies. In general, product prices under such systems are substantially lower than in the United States. Other countries allow companies to fix their own prices for products, but monitor and control company profits.

Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our product candidates. Accordingly, in markets outside the United States, the reimbursement for our products may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenue and profits.

If we are unable to establish or sustain coverage and adequate reimbursement for any future product candidates from third-party payors, the adoption of those products and sales revenue will be adversely affected, which, in turn, could adversely affect the ability to market or sell those product candidates. Coverage policies and third-party reimbursement rates may change at any time. Even if we attain favorable coverage and reimbursement status for one or more products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.

If our competitors develop and market products that are more effective, safer, or less expensive than our product candidates, our commercial opportunities will be negatively impacted.

The biotechnology industry is highly competitive and subject to rapid and significant technological change. Moreover, the oncology field is characterized by strong and increasing competition, with a strong emphasis on intellectual property. Products we may develop in the future for the treatment of cancer and any other diseases are likely to face competition from other drugs and therapies, including those of which we may not currently be aware. In addition, our products may need to compete with off-label drugs used by physicians to treat the indications for which we seek approval. This may make it difficult for us to replace existing therapies with our products.

Major multinational pharmaceutical and biotechnology companies, emerging and start-up companies, universities, and other research institutions, could focus their future efforts on developing competing therapies and treatments for any of the indications we are currently targeting or may target in the future. For example, each of Hoffmann-La Roche AG, Janssen Biotech, Inc., a subsidiary of Johnson & Johnson (in collaboration with Alligator Bioscience AB), Celldex Therapeutics, Inc., Seagen Inc., Eucure Biopharma, a subsidiary of Biocytogen, and AbbVie Inc. are developing CD40-based antibody product candidates for solid tumor oncology indications that are in clinical trials, typically in combination therapies, and other companies and institutions have other CD40-based product candidates in development.

Many of these current and potential competitors have significantly greater financial, manufacturing, marketing, drug development, technical and human resources, and commercial expertise than we do. Large pharmaceutical and biotechnology companies, in particular, have extensive experience in clinical testing, obtaining regulatory approvals, recruiting patients, and manufacturing biotechnology products. These companies also have significantly greater research, development, and marketing capabilities than we do and may also have products that have been approved or are in late stages of development, and collaborative arrangements in our target markets with leading companies and research institutions. Established pharmaceutical and biotechnology companies may also invest heavily to accelerate discovery and development of novel compounds or to in-license novel compounds that could make the product candidates that we develop obsolete. As a result of any of these

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factors, our competitors may succeed in obtaining approval from the FDA, EMA, or foreign regulatory authorities or discovering, developing, and commercializing products in our field before or more successfully than we do.

Smaller and other early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These companies compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for planned clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs. In addition, the biotechnology industry is characterized by rapid technological change. If we fail to stay at the forefront of technological change, we may be unable to compete effectively. Technological advances or products developed by our competitors may render our technologies or product candidates obsolete, less competitive or not economical.

We have limited resources and are currently focusing our efforts on developing sotigalimab and APX601. As a result, we may fail to capitalize on other product candidates or indications that may ultimately have proven to be more profitable.

We are currently focusing our efforts on developing sotigalimab for a variety of indications, including melanoma, esophageal and GEJ cancers, sarcoma and rectal cancer and advancing the development of APX601 for use in solid tumors. As a result, we may forego or delay pursuit of opportunities for other indications or with other product candidates that may have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable product candidates or profitable market opportunities. Our spending on current and future research and development activities for specific indications may not yield any commercially viable drugs. If we do not accurately evaluate the commercial potential or target markets for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing, or other strategic arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

We may not succeed in our efforts to use our technology platform to expand our pipeline of product candidates and develop marketable products.

Because we have limited financial and managerial resources, we focus our pipeline research efforts on using our APXiMAB platform to identify product candidates to molecular targets of interest. Our business depends on our successful development and commercialization of sotigalimab, APX601, and internal product candidates that may emerge from our preclinical research and development activities. Even if we continue to successfully expand our pipeline, development of the potential product candidates that we identify will require substantial investment in clinical development, management of preclinical, clinical, and manufacturing activities, regulatory approval in multiple jurisdictions, obtaining manufacturing supply capability, building a commercial organization, and significant marketing efforts before we generate any revenue from product sales. Furthermore, such product candidates may not be suitable for clinical development, including as a result of their harmful side effects, limited efficacy, or other characteristics that indicate that they are unlikely to be products that will receive marketing approval and achieve market acceptance. If we cannot validate our technology platform by successfully developing and commercializing product candidates based upon our technological approach, we may not obtain product or partnership revenue in future periods, which would adversely affect our business, prospects, financial condition, and results of operations.

We are developing some our product candidates for use in combination with standard-of-care as well as emerging or experimental cancer therapies, which exposes us to several risks beyond our control.

We are developing some of our product candidates, including sotigalimab, for use in combination with current standard of care or other emerging or experimental cancer therapies. This exposes us to supply risk to the extent there is not an adequate supply of these therapies for use in combination with our product candidates, either in

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clinical trials or after any approval, as well as pricing risk if these combination therapies are expensive and the addition of our product candidates would be too costly to support reimbursement or payor coverage. In particular, providers of some of these emerging or experimental therapies have been contributing their therapies to use in combination trials at generally no or limited cost to us. If this were to change, our trial costs could increase substantially. Also, although combinations with an experimental agent that has not been approved may prove to be clinically beneficial, the experimental agent will still need to meet regulatory approval requirements for the combined therapy to become commercially available. In addition, if the standard of care were to evolve or change, the clinical utility of our product candidates could be diminished or eliminated. If any of these were to occur, our business could be materially harmed.

We may use companion diagnostics in the future in our development programs, and if such companion diagnostics for our product candidates are not successfully, and in a timely manner, validated, developed, or approved, we may not achieve marketing approval or realize the full commercial potential of our product candidates.

We may use companion diagnostics in our future product candidate development programs. If such companion diagnostics are developed in conjunction with clinical programs, the FDA, EMA, or comparable regulatory authority may require regulatory approval of a companion diagnostic as a condition to approval of the product candidate. For example, if we use a diagnostic to test which patients are most likely to benefit from our product candidate for the treatment of a particular indication as a criterion for enrollment, then we will likely be required to obtain FDA approval or clearance of the companion diagnostic, concurrent with approval of our product candidate. We may also be required to demonstrate to the FDA the predictive utility of a companion diagnostic, i.e. that the diagnostic selects for patients in whom the therapy will be effective or more effective compared to patients not selected for by the diagnostic. We do not have experience or capabilities in developing or commercializing diagnostics and plan to rely in large part on third parties to perform these functions. We do not currently have any agreement in place with any third party to develop or commercialize companion diagnostics for any of our product candidates. Companion diagnostics are subject to regulation by the FDA, the EMA, and other foreign regulatory authorities as medical devices and require separate regulatory approval or clearance prior to commercialization.

• If we or our partners, or any third party, are unable to successfully develop companion diagnostics in the future in our product candidates, or experience delays in doing so:

• the development of our product candidates may be adversely affected if we are unable to appropriately select patients for enrollment in our planned clinical trials;

• our product candidates may not receive marketing approval if their safe and effective use depends on a companion diagnostic; and

• we may not realize the full commercial potential of any product candidates that receive marketing approval if, among other reasons, we are unable to appropriately identify patients targeted by our product candidates.

In addition, any future product candidates developed in conjunction with companion diagnostics may be perceived negatively compared to alternative treatments that do not require the use of companion diagnostics, either due to the additional cost of the companion diagnostic, the requirement of samples for testing, or the need to complete additional procedures to identify genetic markers prior to administering our product candidates. If any of these events were to occur, it would significantly harm our business, results of operations and prospects.

Our business entails a significant risk of product liability, and if we are unable to obtain sufficient insurance coverage, the costs of product liability could have an adverse effect on our business and financial condition.

Our business exposes us to significant product liability risks inherent in the development, testing, manufacturing, and marketing of therapeutic treatments. Product liability claims could delay or prevent completion of our

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development programs. If we succeed in marketing products, such claims could result in an FDA, EMA, or other regulatory investigation of the safety and effectiveness of our products, our manufacturing processes and facilities, or our marketing programs. Such regulatory investigation could potentially lead to a recall of our products or more serious enforcement action, limitations on the approved indications for which they may be used, or suspension or withdrawal of approvals. Regardless of the merits or eventual outcome, liability claims may also result in decreased demand for our products, injury to our reputation, costs to defend the related litigation, a diversion of management’s time and our resources, and substantial monetary awards to trial participants or patients. We would expect to obtain product liability insurance prior to marketing any of our product candidates. Any insurance Apexigen has now or that we may obtain may not provide sufficient coverage against potential liabilities. Furthermore, clinical trial and product liability insurance is becoming increasingly expensive. As a result, we may be unable to obtain sufficient insurance at a reasonable cost to protect us against losses caused by product liability claims that could have an adverse effect on our business and financial condition.

Risks Related to Regulatory Approval and Other Legal Compliance Matters for Our Product Candidates

The regulatory approval processes of the FDA, EMA, and comparable foreign regulatory authorities are lengthy, time-consuming and inherently unpredictable. If we are ultimately unable to obtain regulatory approval for our product candidates, we will be unable to generate product revenue and our business will be substantially harmed.

The time required to obtain approval by the FDA, EMA, and comparable foreign regulatory authorities is unpredictable, typically takes many years following the commencement of clinical trials, and depends upon numerous factors, including the type, complexity, and novelty of the product candidates involved. In addition, approval policies, regulations, or the type and amount of clinical data necessary to gain approval may change during the course of a product candidate’s clinical development and may vary among jurisdictions, which may cause delays in the approval or the decision not to approve an application. Regulatory authorities have substantial discretion in the approval process and may refuse to accept any application or may decide that our data are insufficient for approval and require additional preclinical, clinical, or other studies. We have not submitted for, or obtained regulatory approval for, any product candidate, and it is possible that none of our existing product candidates or any product candidates we may seek to develop in the future will ever obtain regulatory approval.

Applications for our product candidates could fail to receive regulatory approval in an initial or subsequent indication for many reasons, including the following:

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

• the FDA, EMA, or comparable foreign regulatory authorities may determine that our product candidates are not safe and effective, only moderately effective, or have undesirable or unintended side effects, toxicities, or other characteristics that preclude our obtaining marketing approval or prevent or limit commercial use;

• the population studied in the clinical program may not be sufficiently broad or representative to assure safety and efficacy in the full population for which we seek approval, including for example due to biologic and genetic differences that might occur in subjects in certain populations such as defined by race or other factors;

• we may be unable to demonstrate to the FDA, EMA, or comparable foreign regulatory authorities that a product candidate’s risk-benefit ratio when compared to the standard of care is acceptable;

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

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• the data collected from clinical trials of our product candidates may not be sufficient to support the submission of a Biologics License Application (“BLA”), New Drug Application (“NDA”), or other submission or to obtain regulatory approval in the United States or elsewhere;

• we may be unable to demonstrate to the FDA, EMA, or comparable foreign regulatory authorities that a product candidate’s risk-benefit ratio for a proposed indication is acceptable;

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

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

Further, development of our product candidates and/or regulatory approval may be delayed for reasons beyond our control. For example, a U.S. federal government shutdown or budget sequestration, such as ones that occurred during 2018 and 2019, or other FDA priorities, such as responding to COVID-19, may result in significant reductions to, or demands on, the FDA’s budget, employees, and operations, which may lead to slower response times and longer review periods, potentially affecting our ability to progress development of our product candidates or obtain regulatory approval for our product candidates.

This lengthy approval process, as well as the unpredictability of the results of clinical trials, may result in our failing to obtain regulatory approval to market any of our product candidates, which would significantly harm our business, results of operations, and prospects.

Our product candidates may cause undesirable side effects or have other properties that could prevent their regulatory approval or result in significant negative consequences.

Adverse events or other undesirable side effects caused by our product candidates could cause us or regulatory authorities to interrupt, delay, or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA, EMA, or other comparable foreign regulatory authorities. Drug-related side effects could affect patient recruitment, the ability of enrolled patients to complete the trial, and/or result in potential product liability claims. Regardless of merit or eventual outcome, product liability claims may result in impairment of our business reputation, withdrawal of clinical trial participants, costs due to related litigation, distraction of management’s attention from our primary business, initiation of investigations by regulators, substantial monetary awards to patients or other claimants, the inability to commercialize our product candidates, and decreased demand for our product candidates, if approved for commercial sale.

Additionally, if one or more of our product candidates receives marketing approval, and we or others later identify undesirable side effects or adverse events caused by such products, a number of potentially significant negative consequences could result, including:

• regulatory authorities may withdraw approvals of such product and cause us to recall our products;

• regulatory authorities may require additional warnings on the label or impose a more restrictive, narrower indication for use of the agent;

• we may be required to change the way the product is administered or conduct additional clinical trials or post-approval studies;

• we may be required to create a REMS plan, which could include a medication guide outlining the risks of such side effects for distribution to patients, a communication plan for healthcare providers, and/or other elements, such as boxed warning on the packaging, to assure safe use;

• we could be sued and held liable for harm caused to patients; and

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• our reputation may suffer.

Any of these events could prevent us from achieving or maintaining market acceptance of the particular product candidate, if approved, and could significantly harm our business, financial condition, results of operations, and growth prospects.

For any current and future clinical trials for our product candidates outside the United States, the FDA, EMA, and applicable foreign regulatory authorities may not accept data from such trials.

We conduct clinical trials outside the United States, including in Europe, and we may choose to conduct future clinical trials outside the United States. The acceptance of study data from clinical trials conducted outside the United States or another jurisdiction by the FDA, EMA, or applicable foreign regulatory authority may be subject to certain conditions. In cases where data from foreign clinical trials are intended to serve as the basis for marketing approval in the United States, the FDA will generally not approve the application on the basis of foreign data alone unless the data are applicable to the United States population and United States medical practice, and the trials were performed by clinical investigators of recognized competence and pursuant to Good Clinical Practice (“GCP”) regulations. Additionally, the FDA’s clinical trial requirements, including sufficient size of patient populations and statistical powering, must be met. Many foreign regulatory bodies have comparable approval requirements, including appropriate examination of the product in the country-specific population. In addition, such foreign trials would be subject to the applicable local laws of the foreign jurisdictions where the trials are conducted. There can be no assurance that the FDA, EMA, or any applicable foreign regulatory authority will accept data from trials conducted outside of the United States or the applicable jurisdiction. If the FDA, EMA, or any applicable foreign regulatory authority does not accept such data, it may result in the need for additional trials, which would be costly and time-consuming and delay aspects of our business plan, and may result in our product candidates not receiving approval or clearance for commercialization in the applicable jurisdiction.

Obtaining and maintaining regulatory approval of our product candidates in one jurisdiction does not mean that we will succeed in obtaining regulatory approval of our product candidates in other jurisdictions.

Obtaining and maintaining regulatory approval of our product candidates in one jurisdiction does not guarantee that we will obtain or maintain regulatory approval in any other jurisdiction, but a failure or delay in obtaining regulatory approval in one jurisdiction may have a negative effect on the regulatory approval process in others. For example, even if the FDA, EMA, or comparable foreign regulatory authority grants marketing approval of a product candidate, comparable regulatory authorities in foreign jurisdictions must also approve the manufacturing, marketing, and promotion of the product candidate in those countries. Approval procedures vary among jurisdictions and can involve requirements and administrative review periods different from those in the United States, including additional preclinical studies or clinical trials, as clinical trials conducted in one jurisdiction may not be accepted by regulatory authorities in other jurisdictions. In many jurisdictions outside the United States, a product candidate must be approved for reimbursement before it can be approved for sale in that jurisdiction. In some cases, the price that we intend to charge for our products is also subject to approval. Obtaining foreign regulatory approvals and compliance with foreign regulatory requirements could result in significant delays, difficulties, and costs for us and could delay or prevent the introduction of our products in certain countries. If we or any partner we work with fails to comply with the regulatory requirements in international markets or fails to receive applicable marketing approvals, our target market will be reduced, and our ability to realize the full market potential of our product candidates will be harmed.

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Even if we apply for and obtain accelerated approval or Breakthrough Therapy, Fast Track or other designation intended to expedite, facilitate or reduce the cost pursuing development or regulatory review or approval with the FDA or other regulatory authorities for any of our product candidates, there is no guarantee that such designation would lead to faster development, regulatory review, or approval, nor would it increase the likelihood that any such product candidate will receive marketing approval.

If a product candidate is intended for the treatment of a serious condition and nonclinical or clinical data demonstrate the potential to address unmet medical need for such condition or a substantial improvement over available therapy for such condition, a product candidate sponsor may apply for FDA Fast Track or Breakthrough Therapy designation, and there may be other priority designations available under various regulatory bodies. In the future, we may apply for such priority designation depending on the results of our clinical trials. Even though we may apply for and receive a Fast Track, Breakthrough Therapy or other priority designations, such priority designation does not ensure that we will receive marketing approval or that approval will be granted within any particular timeframe. We may not experience a faster development or regulatory review or approval process with the priority designation compared to conventional FDA procedures. In addition, the FDA may withdraw Fast Track or Breakthrough Therapy designation if it believes that the designation is no longer supported by data from our clinical development program. Fast Track or Breakthrough Therapy designation alone does not guarantee qualification for the FDA’s priority review procedures. Further, even if any of our products obtain Fast Track or Breakthrough Therapy designation, this may not lead to earlier regulatory approval or commercialization of our products due to the extensive and time-consuming steps necessary to obtain FDA approval and commercialize a product candidate.

Even if we obtain regulatory approval for a product candidate, our products will remain subject to extensive regulatory scrutiny.

If any of our product candidates are approved, they will be subject to ongoing regulatory requirements for manufacturing, labeling, packaging, storage, advertising, promotion, sampling, record-keeping, conduct of post-marketing studies, and submission of safety, efficacy, and other post-market information, including both federal and state requirements in the United States and requirements of comparable foreign regulatory authorities.

Manufacturers and manufacturers’ facilities are required to comply with extensive requirements imposed by the FDA, EMA, and comparable foreign regulatory authorities, including ensuring that quality control and manufacturing procedures conform to Good Manufacturing Practice (“GMP”) regulations. As such, we and our contract manufacturers will be subject to continual review and inspections to assess compliance with GMP and adherence to commitments made in any BLA, NDA, or Marketing Authorization Application (“MAA”). Accordingly, we and others with whom we work must continue to expend time, money, and effort in all areas of regulatory compliance, including manufacturing, production, and quality control.

Any regulatory approvals that we receive for our product candidates will be subject to limitations on the approved indicated uses for which the product may be marketed and promoted or to the conditions of approval (including potentially the requirement to implement a REMS), or contain requirements for potentially costly post-marketing testing. We will be required to report certain adverse reactions and production problems, if any, to the FDA, EMA, and comparable foreign regulatory authorities. Any new legislation addressing drug safety issues could result in delays in product development or commercialization, or increased costs to assure compliance. The FDA and other agencies, including the Department of Justice, closely regulate and monitor the post-approval marketing and promotion of products to ensure that they are manufactured, marketed, and distributed only for the approved indications and in accordance with the provisions of the approved labeling. We will have to comply with requirements concerning advertising and promotion for our products. Promotional communications with respect to prescription drugs are subject to a variety of legal and regulatory restrictions and must be consistent with the information in the product’s approved label. As such, we may not promote our products for indications or uses for which they do not have approval. The holder of an approved BLA, NDA, or MAA must submit new or supplemental applications and obtain approval for certain changes to the approved

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product, product labeling, or manufacturing process. We could also be asked to conduct post-marketing clinical trials to verify the safety and efficacy of our products in general or in specific patient subsets. If original marketing approval was obtained via the accelerated approval pathway, we could be required to conduct a successful post-marketing clinical trial to confirm clinical benefit for our products. An unsuccessful post-marketing study or failure to complete such a study could result in the withdrawal of marketing approval.

If a regulatory agency discovers previously unknown problems with a product, such as adverse events of unanticipated severity or frequency, or problems with the facility where the product is manufactured, or disagrees with the promotion, marketing, or labeling of a product, such regulatory agency may impose restrictions on that product or us, including requiring withdrawal of the product from the market. If we fail to comply with applicable regulatory requirements, a regulatory agency or enforcement authority may, among other things:

• issue warning letters that would result in adverse publicity;

• impose civil or criminal penalties;

• suspend or withdraw regulatory approvals;

• suspend any of our ongoing clinical trials;

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

• impose restrictions on our operations, including closing our contract manufacturers’ facilities;

• seize or detain products; or

• require a product recall.

Any government investigation of alleged violations of law could require us to expend significant time and resources in response, and could generate negative publicity. Any failure to comply with ongoing regulatory requirements may significantly and adversely affect our ability to commercialize and generate revenue from our products. If regulatory sanctions are applied or if regulatory approval is withdrawn, this would significantly harm our business, financial condition, results of operations, and growth prospects.

Healthcare legislative measures aimed at reducing healthcare costs may have a material adverse effect on our business and results of operations.

Third-party payors, whether domestic or foreign, or governmental or commercial, are developing increasingly sophisticated methods of controlling healthcare costs. In both the United States and certain foreign jurisdictions, there have been a number of legislative and regulatory changes to the healthcare system that could impact our ability to sell our products profitably. In particular, in 2010, the Patient Protection and Affordable Care Act (“ACA”) was enacted, which, among other things, subjected biologic products to potential competition by lower-cost biosimilars, addressed a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted, or injected, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program, extended the Medicaid Drug Rebate Program to utilization of prescriptions of individuals enrolled in Medicaid managed care organizations, subjected manufacturers to new annual fees and taxes for certain branded prescription drugs, and provided incentives to programs that increase the federal government’s comparative effectiveness research. Recent changes in the U.S. administration could lead to repeal of or changes in some or all of the ACA, and complying with any new legislation or reversing changes implemented under the ACA could be time-intensive and expensive, resulting in a material adverse effect on our business. Until the ACA is fully implemented or there is more certainty concerning the future of the ACA, it will be difficult to predict its full impact and influence on our business.

There have been, and likely will continue to be, legislative and regulatory proposals at the foreign, federal and state levels directed at containing or lowering the cost of healthcare. We cannot predict the initiatives that may be

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adopted in the future. The continuing efforts of the government, insurance companies, managed care organizations and other payors of healthcare services to contain or reduce costs of healthcare and/or impose price controls may adversely affect:

• the demand for our products after obtaining any regulatory approval;

• our ability to receive or set a price that we believe is fair for our products;

• our ability to generate revenue and achieve or maintain profitability;

• the level of taxes that we are required to pay; and

• the availability of capital.

We expect that the ACA, as well as other healthcare reform measures that may be adopted in the future, may result in additional reductions in Medicare and other healthcare funding, more rigorous coverage criteria, lower reimbursement and new payment methodologies. This could lower the price that we receive for any approved product. Any denial in coverage or reduction in reimbursement from Medicare or other government-funded programs may result in a similar denial or reduction in payments from private payors, which may prevent us from being able to generate sufficient revenue, attain profitability or commercialize our product candidates, if approved.

Our employees, independent contractors, consultants, commercial partners and vendors may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements.

We are exposed to the risk of fraud, misconduct or other illegal activity by our employees, independent contractors, consultants, commercial partners and vendors. Misconduct by these parties could include intentional, reckless and negligent conduct that fails to:

• comply with the laws of the FDA, EMA and other comparable foreign regulatory authorities;

• provide true, complete and accurate information to the FDA, EMA and other comparable foreign regulatory authorities;

• comply with manufacturing standards we have established;

• comply with healthcare fraud and abuse laws in the United States and similar foreign fraudulent misconduct laws; or

• report financial information or data accurately or to disclose unauthorized activities to us.

If we obtain FDA approval of any of our product candidates and begin commercializing those products in the United States, our potential exposure under such laws will increase significantly, and our costs associated with compliance with such laws are also likely to increase. In particular, research, sales, marketing, education and other business arrangements in the healthcare industry are subject to extensive laws designed to prevent fraud, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, educating, marketing and promotion, sales and commission, certain customer incentive programs and other business arrangements generally. Activities subject to these laws also involve the improper use of information obtained in the course of patient recruitment for clinical trials, which could result in regulatory sanctions and cause serious harm to our reputation. We plan to adopt a code of business conduct and ethics in connection with this offering, but it is not always possible to identify and deter misconduct by employees and third parties, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business, including the imposition of significant fines or other sanctions.

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If we fail to comply with healthcare laws, we could face substantial penalties and our business, operations, and financial conditions could be adversely affected.

If we obtain FDA approval for any of our product candidates and begin commercializing those products in the United States, our operations will be subject to various federal and state fraud and abuse laws. The laws that may impact our operations include the following:

• The federal Anti-Kickback Statute prohibits, among other things, persons from knowingly and willfully soliciting, receiving, offering, or paying any remuneration (including any kickback, bribe, or rebate), directly or indirectly, overtly or covertly, in cash or in kind, to induce, or in return for, either the referral of an individual, or the purchase, lease, order, or recommendation of any good, facility, item, or service for which payment may be made, in whole or in part, under a federal healthcare program, such as the Medicare and Medicaid programs. A person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation. In addition, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the False Claims Act.

• Federal civil and criminal false claims laws and civil monetary penalty laws, including the False Claims Act, impose criminal and civil penalties, including through civil actions, against individuals or entities from knowingly presenting, or causing to be presented, claims for payment or approval from Medicare, Medicaid or other third-party payors that are false or fraudulent, or knowingly making a false statement to improperly avoid, decrease or conceal an obligation to pay money to the federal government. Similar to the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of these statutes or specific intent to violate them in order to have committed a violation.

• The Health Insurance Portability and Accountability Act of 1996 (“HIPAA”) created new federal criminal statutes that prohibit knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program or obtain, by means of false or fraudulent pretenses, representations or promises, any of the money or property owned by, or under the custody or control of, any healthcare benefit program, regardless of the payor (e.g., public or private) and knowingly and willfully falsifying, concealing, or covering up by any trick or device a material fact or making any materially false statements in connection with the delivery of, or payment for, healthcare benefits, items or services relating to healthcare matters.

• HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009 (“HITECH”) and their respective implementing regulations, impose requirements on certain covered healthcare providers, health plans, and healthcare clearinghouses as well as their respective business associates that perform services for them that involve the use, or disclosure of, individually identifiable health information, relating to the privacy, security, and transmission of individually identifiable health information without appropriate authorization.

• The federal Physician Payment Sunshine Act, created under the ACA, and its implementing regulations, require manufacturers of drugs, devices, biologicals, and medical supplies for which payment is available under Medicare, Medicaid or the Children’s Health Insurance Program to report annually to the HHS under the Open Payments Program, information related to payments or other transfers of value made to physicians and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members.

• Federal consumer protection and unfair competition laws broadly regulate marketplace activities and activities that potentially harm consumers.

Analogous state and foreign laws and regulations, such as state and foreign anti-kickback, false claims, consumer protection, and unfair competition laws may apply to pharmaceutical business practices, including research,

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distribution, sales, and marketing arrangements, as well as submitting claims involving healthcare items or services reimbursed by any third-party payor, including commercial insurers.

• 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 that otherwise restricts payments that may be made to healthcare providers and other potential referral sources.

• State laws also require drug manufacturers to file reports with states regarding pricing and marketing information, such as the tracking and reporting of gifts, compensations, and other remuneration, and items of value provided to healthcare professionals and entities.

• State and foreign laws also govern the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways and may not have the same effect, thus complicating compliance efforts.

Because of the breadth of these laws and the narrowness of the statutory exceptions and safe harbors available, it is possible that some of our business activities could, despite our efforts to comply, be subject to challenge under one or more of such laws. Efforts to ensure that our business arrangements will comply with applicable healthcare laws may involve substantial costs. It is possible that governmental and enforcement authorities will conclude that our business practices may not comply with current or future statutes, regulations or case law interpreting applicable fraud and abuse or other healthcare laws and regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business, including the imposition of civil, criminal and administrative penalties, damages, disgorgement, monetary fines, possible exclusion from participation in Medicare, Medicaid, and other federal healthcare programs, contractual damages, reputational harm, diminished profits and future earnings, and curtailment of our operations, any of which could adversely affect our ability to operate our business and our results of operations. In addition, the approval and commercialization of any of our product candidates outside the United States will also likely subject us to foreign equivalents of the healthcare laws mentioned above, among other foreign laws. Further, achieving and sustaining compliance with applicable federal and state privacy, security, and fraud laws may prove costly.

If we or any clinical collaborators, CROs, contract manufacturers, or other contractors and suppliers that we engage fail to comply with environmental, health, and safety laws and regulations, we could become subject to fines or penalties or incur costs that could have a material adverse effect on our business.

We and any clinical collaborators, CROs, contract manufacturers, or other contractors and suppliers that we engage are subject to numerous federal, state, and local environmental, health and safety laws, regulations, and permitting requirements, including:

• those governing laboratory procedures;

• the generation, handling, use, storage, treatment and disposal of hazardous and regulated materials and wastes;

• the emission and discharge of hazardous materials into the ground, air and water; and

• employee health and safety.

Our operations involve the use of hazardous and flammable materials, including chemicals and biological and radioactive materials. Our operations also produce hazardous waste. 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. Under certain environmental laws, we could be held responsible for costs relating to any contamination at our current or past facilities and at third-party facilities. We also could incur significant costs associated with civil or criminal fines and penalties.

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Compliance with applicable environmental laws and regulations may be expensive, and current or future environmental laws and regulations may impair our research, product development, and manufacturing efforts. In addition, we cannot entirely eliminate the risk of accidental injury or contamination from these materials or wastes. 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 carry specific biological or hazardous waste insurance coverage, and our property, casualty, and general liability insurance policies specifically exclude coverage for damages and fines arising from biological or hazardous waste exposure or contamination. Accordingly, in the event of contamination or injury, we could be held liable for damages or be penalized with fines in an amount exceeding our resources, and our clinical trials or regulatory approvals could be suspended, which could have a material adverse effect on our business, financial condition, results of operations, and prospects.

Our business activities may be subject to the FCPA and similar anti-bribery and anti-corruption laws.

Our business activities may be subject to the Foreign Corrupt Practices Act (“FCPA”) and similar anti-bribery or anti-corruption laws, regulations, or rules of other countries in which we operate, including the U.K. Bribery Act. The FCPA generally prohibits offering, promising, giving, or authorizing others to give anything of value, either directly or indirectly, to a non-U.S. government official in order to influence official action, or otherwise obtain or retain business. The FCPA also requires public companies to make and keep books and records that accurately and fairly reflect the transactions of the corporation and to devise and maintain an adequate system of internal accounting controls. Our business is heavily regulated and therefore involves significant interaction with public officials, including officials of non-U.S. governments. Additionally, in many other countries, the researchers with whom we conduct clinical trials, and the healthcare providers who prescribe pharmaceuticals, are employed by their government, and the purchasers of pharmaceuticals are government entities. As a result, our dealings with these researchers, prescribers, and purchasers are subject to regulation under the FCPA. Recently the Securities and Exchange Commission (“SEC”) and Department of Justice have increased their FCPA enforcement activities with respect to biotechnology and pharmaceutical companies. There is no certainty that all of our employees, agents, contractors or collaborators, or those of our affiliates, will comply with all applicable laws and regulations, particularly given the high level of complexity of these laws. Violations of these laws and regulations could result in fines, criminal sanctions against us, our officers or our employees, the closing down of our facilities, requirements to obtain export licenses, cessation of business activities in sanctioned countries, implementation of compliance programs and prohibitions on the conduct of our business. Any such violations could include prohibitions on our ability to offer our products in one or more countries and could materially damage our reputation, our brand, our international expansion efforts, our ability to attract and retain employees, and our business, prospects, operating results and financial condition.

Failure to comply with privacy and data protection laws, regulations, or contractual obligations could lead to government enforcement actions (which could include civil or criminal penalties), private disputes and litigation, and/or adverse publicity and could negatively affect our operating results and business.

We receive, generate, and store significant and increasing volumes of sensitive information, such as employee, personal, patient and collaborator data. In addition, we actively seek access to medical information, including patient data, through research and development partnerships and collaborations or otherwise. We have legal and contractual obligations regarding the protection of confidentiality and appropriate use of personal data. We and our partners may be subject to federal, state, and foreign data protection laws and regulations (i.e., laws and regulations that address privacy and data security). These data protection laws and regulations continue to evolve and may result in ever-increasing public scrutiny and escalating levels of enforcement and sanctions and increased costs of compliance.

In the United States, numerous federal and state laws and regulations, including state data breach notification laws, state health information privacy laws, and federal and state consumer protection laws (e.g., Section 5 of the

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Federal Trade Commission Act), that govern the collection, use, disclosure and protection of health-related and other personal information could apply to our operations or the operations of our partners, including during our clinical trials. In addition, we may obtain health information from third parties (including research institutions from which we obtain clinical trial data) that are subject to privacy and security requirements under HIPAA, as amended by HITECH, which establish privacy and security standards that limit the use and disclosure of individually identifiable health information and require the implementation of administrative, physical, and technological safeguards to protect the privacy of individually identifiable health information and ensure the confidentiality, integrity, and availability of electronic protected health information. Determining whether individually identifiable health information has been handled in compliance with applicable privacy standards and our contractual obligations can require complex factual and statistical analyses and may be subject to changing interpretation. Depending on the facts and circumstances, we could be subject to civil and criminal penalties if we knowingly obtain, use, or disclose individually identifiable health information maintained by a HIPAA-covered entity in a manner that is not authorized or permitted by HIPAA. Enforcement activity can result in financial liability and reputational harm, and responses to such enforcement activity can consume significant internal resources. We cannot be sure how these regulations will be interpreted, enforced, or applied to our operations. In addition to the risks associated with enforcement activities and potential contractual liabilities, our ongoing efforts to comply with evolving laws and regulations at the federal and state level may be costly and require ongoing modifications to our policies, procedures and systems. Failure to comply with any of these laws could result in enforcement action against us, including fines, imprisonment of company officials and public censure, claims for damages by customers and other affected individuals, damage to our reputation, and loss of goodwill (both in relation to existing and prospective customers), any of which could have a material adverse effect on our business, financial condition, results of operations, or prospects.

Although we take measures to protect sensitive data from unauthorized access, use or disclosure, our information technology and infrastructure may be vulnerable to attacks by hackers or viruses or breached due to employee error, malfeasance, or other malicious or inadvertent disruptions. Any such breach or interruption could compromise our networks and the information stored there could be accessed by unauthorized parties, manipulated, publicly disclosed, lost or stolen. Any such access, breach or other loss of information could result in legal claims or proceedings, and liability under federal or state laws that protect the privacy of personal information, such as HIPAA and HITECH, and regulatory penalties. Notice of breaches must be made to affected individuals, the Secretary of the HHS, and for extensive breaches, notice may need to be made to the media or State Attorneys General. Such a notice could harm our reputation and our ability to compete. The HHS has the discretion to impose penalties without attempting to resolve violations through informal means. In addition, state attorneys general are authorized to bring civil actions seeking either injunctions or damages in response to violations that threaten the privacy of state residents. Although we have implemented security measures to prevent unauthorized access to patient data, such data is currently accessible through multiple channels, and there is no guarantee we can protect our data from breach. Unauthorized access, loss, or dissemination could also damage our reputation or disrupt our operations, including our ability to conduct our analyses, deliver test results, process claims and appeals, provide customer assistance, conduct research and development activities, collect, process and prepare company financial information, provide information about our tests and other patient and physician education and outreach efforts through our website, and manage the administrative aspects of our business.

We may collect, process, use or transfer personal information from individuals located in the European Union in connection with our business, including in connection with conducting clinical trials in the European Union. Additionally, if any of our product candidates are approved, we may seek to commercialize those products in the European Union. The collection and use of personal health data in the European Union are governed by laws, regulations, and directives, including the General Data Protection Regulation (EU) 2016/679 (“GDPR”). This legislation imposes requirements relating to having legal bases for processing personal information relating to identifiable individuals and transferring such information outside of the European Economic Area, including to the United States, providing details to those individuals regarding the processing of their personal information, keeping personal information secure, having data processing agreements with third parties who process personal

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information, responding to individuals’ requests to exercise their rights in respect of their personal information, reporting security breaches involving personal data to the competent national data protection authority and affected individuals, appointing data protection officers, conducting data protection impact assessments and record-keeping. This legislation imposes significant responsibilities and liabilities in relation to personal data that we process, and we may be required to put in place additional mechanisms ensuring compliance. In particular, with respect to cross-border transfers of personal data, judicial and regulatory developments in the European Union have created uncertainty. In a decision issued by the Court of Justice of the European Union (“CJEU”) on July 16, 2020, the CJEU invalidated one mechanism for cross-border personal data transfer, the EU-U.S. Privacy Shield, and imposed additional obligations on companies, including us, relying on standard contractual clauses (“SCCs”) issued by the European Commission for cross-border personal data transfers. The European Commission released new SCCs designed to address the CJEU concerns on June 4, 2021. We have undertaken certain efforts to conform transfers of personal data from the European Economic Area (“EEA”) to the United States to our understanding of current regulatory obligations and guidance of data protection authorities, but the CJEU’s decision, the revised SCCs, regulatory guidance and opinions, and other developments relating to cross-border data transfer may require us to implement additional contractual and technical safeguards for any personal data transferred out of the EEA, which may increase compliance costs, lead to increased regulatory scrutiny or liability, may require additional contractual negotiations, and may adversely impact our business, financial condition and operating results. Any actual or alleged failure to comply with the requirements of the GDPR or other laws, regulations, and directives of the member states of the European Union may result in substantial fines, other administrative penalties and civil claims being brought against us, which could have a material adverse effect on our business, financial condition and results of operations.

In addition, U.S. states are adopting new laws or amending existing laws and regulations, requiring attention to frequently changing regulatory requirements applicable to data related to individuals. For example, California has enacted the California Consumer Privacy Act (“CCPA”). The CCPA gives California residents expanded rights to access and delete their personal information, opt out of certain personal information sharing and receive detailed information about how their personal information is used by requiring covered companies to provide new disclosures to California consumers (as that term is broadly defined and which can include any of our current or future employees who may be California residents or any other California residents whose data we collect or process) and provide such residents new ways to opt out of certain sales of personal information. The CCPA provides for civil penalties for violations, as well as a private right of action for data breaches that is expected to increase data breach litigation. As we expand our operations and trials (both preclinical or clinical), the CCPA may increase our compliance costs and potential liability. Additionally, a new privacy law, the California Privacy Rights Act (“CPRA”), was approved by California voters in the election on November 3, 2020. The CPRA creates obligations relating to consumer data beginning on January 1, 2022, with implementing regulations expected on or before July 1, 2022, and enforcement beginning July 1, 2023. The CPRA modifies the CCPA significantly, potentially resulting in further uncertainty and requiring us to incur additional costs and expenses in an effort to comply. Additionally, other U.S. states continue to propose, and in certain cases adopt, privacy-focused legislation such as Colorado, Virginia, Utah and Connecticut. Aspects of these state laws remain unclear, resulting in further uncertainty and potentially requiring us to modify our data practices and policies and to incur substantial additional costs and expenses in an effort to comply.

Failure to comply with U.S. and international data protection laws and regulations could result in government enforcement actions (which could include civil or criminal penalties), private litigation, and/or adverse publicity and could negatively affect our operating results and business. Moreover, patients about whom we or our partners obtain information, as well as the providers who share this information with us, may contractually limit our ability to use and disclose the information. Claims that we have violated individuals’ privacy rights, failed to comply with data protection laws or breached our contractual obligations, even if we are not found liable, could be expensive and time-consuming to defend and could result in adverse publicity that could harm our business.

If we or third parties fail to adequately safeguard confidential personal, employee, or patient data, or if such information or data are wrongfully used by us or third parties or disclosed to unauthorized persons or entities, our

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reputation could suffer and we could be subject to claims for damages or other liabilities, regulatory investigations and enforcement action, litigation, the imposition of fines or other penalties, and significant costs for remediation. Any of these risks could have a material adverse effect on our business, financial condition, results of operations, or prospects.

Risks Related to Employee Matters, Managing Growth and Other Risks Related to Our Business

Our success is highly dependent on the services of our President and Chief Executive Officer, Dr. Xiaodong Yang, and our other senior management, and our ability to attract and retain highly skilled executive officers and employees.

To succeed, we must recruit, retain, manage, and motivate qualified clinical, scientific, technical, and management personnel, and we face significant competition for experienced personnel, especially in the biotechnology industry in the San Francisco Bay Area of California. We are highly dependent on the principal members of our management and scientific and medical staff, particularly our President and Chief Executive Officer, Dr. Xiaodong Yang. If we do not succeed in attracting and retaining qualified personnel, particularly at the management level, it could adversely affect our ability to execute our business plan and harm our operating results. In particular, the loss of one or more of our executive officers, including Dr. Yang, could be detrimental to us if we cannot recruit suitable replacements in a timely manner. The competition for qualified personnel in the biotechnology field is intense and as a result, we may be unable to continue to attract and retain qualified personnel necessary for the future success of our business. In addition to competition for personnel, the San Francisco Bay Area in particular is characterized by a high cost of living. We could in the future have difficulty attracting experienced personnel to our company and may be required to expend significant financial resources in our employee recruitment and retention efforts.

Many of the other biotechnology companies that we compete against for qualified personnel have greater financial and other resources, different risk profiles and a longer history in the industry than we do. They also may provide more diverse opportunities and better prospects for career advancement. Some of these characteristics may be more appealing to high-quality candidates than what we have to offer. If we are unable to continue to attract and retain high-quality personnel, the rate and success at which we can discover, develop, and commercialize our product candidates will be limited and the potential for successfully growing our business will be harmed.

In order to successfully implement our plans and strategies, we will need to grow the size of our organization, and we may experience difficulties in managing this growth.

As of July 29, 2022, Apexigen had 22 full-time employees, 15 of whom were engaged in research and development activities. In order to successfully implement our development and commercialization plans and strategies, and as we transition into operating as a public company after the Business Combination, we expect to need additional managerial, operational, sales, marketing, financial, and other personnel. Future growth would impose significant added responsibilities on members of management, including:

• identifying, recruiting, integrating, maintaining, and motivating additional employees;

• managing our internal development efforts effectively, including the clinical and FDA and EMA review process for our current and any future product candidates, while complying with any contractual obligations to contractors and other third parties we may have; and

• improving our operational, financial and management controls, reporting systems and procedures.

Our future financial performance and our ability to successfully develop and, if approved, commercialize our current and any future product candidates will depend, in part, on our ability to effectively manage any future growth, and our management may also have to divert a disproportionate amount of its attention away from day-to-day activities in order to devote a substantial amount of time to managing these growth activities.

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We currently rely, and for the foreseeable future will continue to rely, in substantial part on certain independent organizations, advisors and consultants to provide certain services, including substantially all aspects of clinical management and manufacturing. We cannot assure you that the services of independent organizations, advisors and consultants will continue to be available to us on a timely basis when needed, or that we can find qualified replacements. In addition, if we are unable to effectively manage our outsourced activities or if the quality or accuracy of the services provided by third party service providers is compromised for any reason, our clinical trials may be extended, delayed or terminated, and we may not obtain marketing approval of our current and any future product candidates or otherwise advance our business. We cannot assure you that we will manage our existing third-party service providers or find other competent outside contractors and consultants on economically reasonable terms, or at all.

If we are not able to effectively expand our organization by hiring new employees and/or engaging additional third-party service providers, we may not successfully implement the tasks necessary to further develop and commercialize our current and any future product candidates and, accordingly, may not achieve our research, development, and commercialization goals.

If we are unable to establish sales or marketing capabilities or enter into agreements with third parties to sell or market our product candidates after any approvals, we may not successfully sell or market our product candidates that obtain regulatory approval.

We currently do not have and have never had a marketing or sales team for the marketing, sales and distribution of any of our product candidates that may obtain regulatory approval in the future. In order to commercialize any product candidates, we must build marketing, sales, distribution, managerial, and other non-technical capabilities or make arrangements with third parties to perform these services for each of the territories in which we may have approval to sell or market our product candidates. We may not be successful in accomplishing these required tasks.

Establishing an internal sales or marketing team with technical expertise and supporting distribution capabilities to commercialize our product candidates will be expensive and time-consuming, and will require significant attention of our executive officers to manage. Any failure or delay in the development of our internal sales, marketing, and distribution capabilities could adversely impact the commercialization of any of our product candidates that we obtain approval to market, if we do not have arrangements in place with third parties to provide such services on our behalf. Alternatively, if we choose to collaborate, either globally or on a territory-by-territory basis, with third parties that have direct sales forces and established distribution systems, either to augment our own sales force and distribution systems or in lieu of our own sales force and distribution systems, we will be required to negotiate and enter into arrangements with such third parties relating to the proposed collaboration. If we are unable to enter into such arrangements when needed on acceptable terms, or at all, we may not successfully commercialize any of our product candidates that receive regulatory approval or any such commercialization may experience delays or limitations. If we are unable to successfully commercialize our approved product candidates, either on our own or through collaborations with one or more third parties, our future product revenue will suffer and we may incur significant additional losses.

Our anticipated international operations may expose us to business, regulatory, political, operational, financial, pricing, and reimbursement risks associated with doing business outside of the United States.

Our business strategy incorporates potential international expansion as we seek to obtain regulatory approval for, and commercialize, our current and any future product candidates in patient populations outside the United States. If our product candidates are approved, we may hire sales representatives and conduct physician and patient association outreach activities outside of the United States. Doing business internationally involves a number of risks, including:

• multiple, conflicting, and changing laws and regulations such as privacy regulations, tax laws, export and import restrictions, employment laws, regulatory requirements, and other governmental approvals, permits and licenses;

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• failure by us to obtain and maintain regulatory approvals for the use of our products in various countries;

• rejection or qualification of foreign clinical trial data by the competent authorities of other countries;

• additional potentially relevant third-party patent rights;

• complexities and difficulties in obtaining protection and enforcing our intellectual property;

• difficulties in staffing and managing foreign operations;

• complexities associated with managing multiple payor reimbursement regimes, government payors, or patient self-pay systems;

• limits in our ability to penetrate international markets;

• financial risks, such as longer payment cycles, difficulty collecting accounts receivable, the impact of local and regional financial crises on demand and payment for our products, and exposure to foreign currency exchange rate fluctuations;

• natural disasters, political and economic instability, including wars, terrorism, and political unrest, outbreak of disease, boycotts, curtailment of trade, and other business restrictions;

• certain expenses including, among others, expenses for travel, translation, and insurance; and

• regulatory and compliance risks that relate to anti-corruption compliance and record-keeping that may fall within the purview of the FCPA, its accounting provisions or its anti-bribery provisions, or provisions of anti-corruption or anti-bribery laws in other countries.

Any of these factors could significantly harm our future international expansion and operations and, consequently, our results of operations.

Risks Related to Intellectual Property

If we are unable to obtain, maintain or protect intellectual property rights in any products we develop and in our technology, or if the scope of the intellectual property protection obtained is not sufficiently broad, third parties could develop and commercialize products and technology similar or identical to ours, and we may not compete effectively in our market.

Our success depends in significant part on our and our current or future licensors’ ability to obtain, maintain and protect patents and other intellectual property rights and operate without infringing, misappropriating, or otherwise violating the intellectual property rights of others. We have filed numerous patent applications both in the United States and in foreign jurisdictions to obtain patent rights to inventions we have developed that are important to our business, including related to our product candidates. We have also licensed from third parties rights to patents and other intellectual property, including from Epitomics, Inc., an Abcam Company (“Epitomics”), with respect to rabbit monoclonal antibodies generated using Epitomics’ technology in the field of pharmaceutical products for human or veterinary use. If we or our licensors are unable to obtain or maintain patent protection with respect to such inventions and technology, our business, financial condition, results of operations, and prospects could be materially harmed.

The patent prosecution process is expensive, time-consuming, and complex, and we and our current or future licensors may not prepare, file, prosecute, maintain, and enforce all necessary or desirable patent applications at a reasonable cost or in a timely manner. Patents may be invalidated and patent applications may not be granted for a number of reasons, including known and unknown prior art, deficiencies in the patent applications or the lack of novelty of the underlying inventions or technology. It is also possible that we or our current and future licensors will fail to identify patentable aspects of inventions made in the course of research, development and commercialization activities in time to obtain patent protection. Although we enter into non-disclosure and

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confidentiality agreements with parties who have access to confidential or patentable aspects of our research, development, and commercialization activities, such as our employees, collaborators, CROs, consultants, advisors and other third parties, any of these parties may breach the agreements and disclose such activities before a patent application is filed, thereby jeopardizing our ability to seek patent protection. In addition, publications of discoveries in the scientific literature often lag behind 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 current or future licensors were the first to make the inventions claimed in our owned or any licensed patents or patent applications, or that we or our current or future licensors were the first to file for patent protection of such inventions.

Moreover, in some circumstances, we may not have the right to control the preparation, filing, prosecution, maintenance, enforcement, and defense of patents and patent applications covering technology that we license from third parties and are reliant on our current and future licensors. For example, pursuant to our license agreement with Epitomics, Inc., Epitomics is responsible for the filing, prosecution and maintenance of the patents and patent applications licensed to us. Therefore, these patents and applications may not be prepared, filed, prosecuted, maintained, enforced and defended in a manner consistent with the best interests of our business. If our current or future licensors fail to prosecute, maintain, enforce or defend such patents and other intellectual property rights, are not fully cooperative or disagree with us as to the prosecution, maintenance or enforcement of any patent rights, or lose rights to those patents or patent applications, the rights we have licensed may be reduced or eliminated, and our right to develop and commercialize any of our product candidates that are the subject of such licensed rights could be adversely affected.

The patent position of biotechnology 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 current or future licensors’ patent rights are highly uncertain. Our and our current or future licensors’ pending and future patent applications may not result in patents being issued which protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. Moreover, the patent examination process may require us or our current and future licensors to narrow the scope of the claims of our or our current and future licensors’ pending and future patent applications, which may limit the scope of patent protection that may be obtained. Additionally, the scope of patent protection can be reinterpreted after issuance. Even if our or our current or future licensors’ pending and future patent applications issue as patents, they may not issue in a form that will provide us with any meaningful protection, prevent competitors or other third parties from competing with us, or otherwise provide us with any competitive advantage. Any patents that we hold or in-license may be challenged, narrowed, circumvented, or invalidated by third parties in court or in patent offices in the United States and abroad. Our and our current or future licensors’ patent applications cannot be enforced against third parties practicing the technology claimed in such applications unless and until a patent issues from such applications, and then only to the extent the issued claims cover the technology. Our competitors or other third parties may also circumvent our patents by developing similar or alternative technologies or products in a non-infringing manner.

We cannot assure you that we have found all of the potentially relevant prior art relating to our patents and patent applications. If such prior art exists, it can invalidate a patent or prevent a patent from issuing from a pending patent application. For example, there are a number of third-party patents and patent applications relating to the engineering of antibodies, including with respect to the CD40 binding and fragment crystallizable (“Fc”) domains, that may have earlier priority or publication dates and may be asserted as prior art against our patents and patent applications. Even if our patents do issue and even if such patents cover our product candidates, third parties may initiate oppositions, interferences, re-examinations, post-grant reviews, inter partes reviews, nullification or derivation actions in court or before patent offices, or similar proceedings challenging the inventorship, validity, enforceability or scope of such patents, which may result in the patent claims being narrowed or invalidated. An adverse determination in any such proceeding or litigation could reduce the scope of, or invalidate, the patent rights we own or license, allow third parties to commercialize our technology or products and compete directly with us, without payment to us.

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Moreover, we, or our current or future licensors, may have to participate in interference proceedings declared by the United States Patent and Trademark Office (“USPTO”) to determine priority of invention or in post-grant challenge proceedings, such as oppositions in a foreign patent office, that challenge priority of invention or other features of patentability. Such challenges may result in loss of patent rights, loss of exclusivity, or in patent claims being narrowed, invalidated, or held unenforceable, which could limit our ability to stop others from using or commercializing similar or identical technology and products, or limit the duration of the patent protection of our technology and product candidates, including sotigalimab. Such proceedings also may result in substantial cost and require significant time from our scientists and management, even if the eventual outcome is favorable to us. Consequently, we do not know whether any of our technology or product candidates will be protectable or remain protected by valid and enforceable patents.

Because patent applications in the United States and most other countries are confidential for a period of time after filing, and some remain so until issued, we cannot be certain that we or our current and future licensors were the first to file any patent application related to a product candidate. Furthermore, if third parties have filed such patent applications on or before March 15, 2013, an interference proceeding in the United States can be initiated by such third parties to determine who was the first to invent any of the subject matter covered by the patent claims of our applications. If third parties have filed such applications after March 15, 2013, a derivation proceeding in the United States can be initiated by such third parties to determine whether our invention was derived from theirs. Even where we have a valid and enforceable patent, we may not exclude others from practicing our invention where the other party can show that they used the invention in commerce before our filing date or the other party benefits from a compulsory license.

We may not protect our intellectual property rights throughout the world.

Filing, prosecuting, enforcing, and defending patents on product candidates in all countries throughout the world would be prohibitively expensive, and our or our current and future licensors’ intellectual property rights may not exist in some countries outside the United States or may be less extensive in some countries than in the United States. In addition, the laws of some foreign countries do not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, we and our current and future licensors may not prevent third parties from practicing our and our current or future licensors’ inventions in all countries outside the United States, or from selling or importing products made using our and our current or future licensors’ inventions in and into the United States or other jurisdictions. Competitors may use our and our current or future licensors’ technologies in jurisdictions where we have not obtained patent protection to develop their own products and, further, may export otherwise infringing products to territories where we and our current and future licensors have patent protection, but enforcement is not as strong as that in the United States. These products may compete with our product candidates, and our and our current or future licensors’ patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents, trade secrets, and other intellectual property protection, particularly those relating to biotechnology, which could make it difficult for us and our current and future licensors to stop the infringement of our and our current or future licensors’ patents or marketing of competing products in violation of our and our current or future licensors’ intellectual property and proprietary rights generally. Proceedings to enforce our and our current or future licensors’ intellectual property and proprietary rights in foreign jurisdictions could result in substantial costs and divert our and our current or future licensors’ efforts and attention from other aspects of our business, could put our and our current or future licensors’ patents at risk of being invalidated or interpreted narrowly, could put our and our current or future licensors’ patent applications at risk of not issuing, and could provoke third parties to assert claims against us or our current and future licensors. We or our current and future licensors may not prevail in any lawsuits that we or our current and future licensors initiate, and the damages or other remedies awarded, if any, may not be commercially meaningful. Some jurisdictions may refuse to honor intellectual property rights due to legislation or geopolitical reasons, such as Russia recently stating that

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it will not honor patent rights of companies from countries that have imposed sanctions on Russia in response to the war in Ukraine. Accordingly, our and our current and future licensors’ efforts to enforce intellectual property and proprietary rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that we develop or license.

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

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

Obtaining and enforcing patents in the biopharmaceutical industry involves both technological and legal complexity and is therefore costly, time-consuming, and inherently uncertain. Changes in either the patent laws or interpretation of the patent laws in the United States could increase the uncertainties and costs surrounding the prosecution of patent applications and the enforcement or defense of issued patents. Recent patent reform legislation in the United States and other countries, including the Leahy-Smith America Invents Act (“Leahy-Smith Act”), could increase those uncertainties and costs. The Leahy-Smith Act includes provisions that affect the way patent applications are prosecuted, redefine prior art, and provide more efficient and cost-effective avenues for competitors to challenge the validity of patents, and may also affect patent litigation. These include allowing third-party submission of prior art to the USPTO during patent prosecution and additional procedures to attack the validity of a patent by USPTO administered post-grant proceedings, including post-grant review, inter partes review, and derivation proceedings. In addition, assuming that other requirements for patentability are met, prior to March 15, 2013, in the United States, the first to invent the claimed invention was entitled to the patent, while outside the United States, the first to file a patent application was entitled to the patent. After March 15, 2013, under the Leahy-Smith Act, the United States transitioned to a first inventor to file system in which, assuming that the other statutory requirements are met, the first inventor to file a patent application will be entitled to the patent on an invention regardless of whether a third party was the first to invent the claimed invention. However, the Leahy-Smith Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of which could have a material adverse effect on our business, financial condition, results of operations, and prospects.

In addition, the U.S. Supreme Court has ruled on several patent cases in recent years, either narrowing the scope of patent protection available in certain circumstances or weakening the rights of patent owners in certain situations. This combination of events has created uncertainty with respect to the validity and enforceability of patents, once obtained. Depending on future actions by the U.S. Congress, the U.S. courts, the USPTO and the relevant law-making bodies in other countries, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future.

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

Periodic maintenance fees, renewal fees, annuity fees, and various other government fees on any issued patent or patent application are due to be paid to the USPTO and various government patent agencies outside of the United States in several stages over the lifetime of our owned or licensed patents and applications. The USPTO and various non-U.S. governmental patent agencies require compliance with a number of procedural, documentary,

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fee payment, and other similar provisions during the patent application process. While an inadvertent lapse can, in some cases, be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which non-compliance can result in abandonment or lapse of the patent or patent application, resulting in a partial or complete loss of patent rights in the relevant jurisdiction. Non-compliance events that could result in abandonment or lapse of a patent or patent application include failure to respond to official actions within prescribed time limits, non-payment of fees, and failure to properly legalize and submit formal documents. If we or our current and future licensors fail to maintain the patents and patent applications covering our product candidates, our patent protection could be reduced or eliminated and our competitors might be better able to enter the market with competing products or technology, which could have a material adverse effect on our business, financial condition, results of operation, and prospects.

If we fail to comply with our obligations in the agreements under which we license intellectual property rights from third parties or otherwise experience disruptions to our business relationships with our licensors, we could lose the ability to continue the development and commercialization of our product candidates.

We are a party to a number of intellectual property and technology licenses that are important to our business. For example, Apexigen obtained an exclusive license from Epitomics under certain intellectual property related to rabbit monoclonal antibodies generated using Epitomics’ technology in the field of pharmaceutical products for human or veterinary use that has certain ongoing payment and other obligations even though the license agreement has now expired. In addition, if we fail to comply with our obligations under these technology agreements, including payment and diligence terms, or other specified events occur such as our insolvency, our current and future licensors may have the right to terminate these agreements, in which event we may not develop, manufacture, market or sell any product that is covered by these agreements or may face other penalties under the agreements. Such an occurrence could adversely affect the value of the technology or product candidate being developed or licensed under any such agreement. Termination of these agreements or reduction or elimination of our rights under these agreements may result in our having to negotiate new or reinstated agreements, which may not be available to us on equally favorable terms, or at all, or cause us to lose our rights under these agreements, including our rights to intellectual property or technology important to our development programs.

Disputes may arise regarding intellectual property subject to a licensing agreement, including:

• the scope of rights granted under the license agreement and other interpretation-related issues;

• the extent to which our technology and processes infringe on intellectual property of the licensor that is not subject to the licensing agreement;

• the sublicensing of patent and other rights under our existing collaborative development relationships and any collaboration relationships we might enter into in the future;

• our diligence obligations under the license agreement and what activities satisfy those diligence obligations;

• the inventorship and ownership of inventions and know-how resulting from the joint creation or use of intellectual property by our current and future licensors and us; and

• the priority of invention of patented technology.

In addition, the agreements under which Apexigen licenses intellectual property or technology from third parties are generally complex, and certain provisions in such agreements may be susceptible to multiple interpretations. The resolution of any contract interpretation disagreement that may arise could narrow what we believe to be the scope of our rights to the relevant intellectual property or technology, or increase what we believe to be our financial or other obligations under the relevant agreement, either of which could have a material adverse effect on our business, financial condition, result of operations, and prospects. Moreover, if disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on

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commercially acceptable terms, we may be unable to successfully develop and commercialize the affected product candidates, which could have a material adverse effect on our business, financial conditions, results of operations, and prospects.

We may not succeed in obtaining necessary rights to any product candidates we may develop through acquisitions and in-licenses.

A third party may hold intellectual property, including patent rights, that are important or necessary to the development of our current or future product candidates. In order to avoid infringing these third-party patents, we may find it necessary or prudent to obtain licenses from such third-party intellectual property holders. Moreover, we may need to obtain additional licenses from our existing licensors and others to advance our research or allow commercialization of product candidates we may develop. In addition, with respect to any patents we co-own with third parties, we may require licenses to such co-owners’ interest to such patents. However, we may be unable to secure such licenses or otherwise acquire or in-license any compositions, methods of use, processes, or other intellectual property rights from third parties that we identify as necessary for product candidates we develop. The licensing or acquisition of third-party intellectual property rights is a competitive area, and several more established companies may pursue strategies to license or acquire third-party intellectual property rights that we may consider attractive or necessary. These established companies may have a competitive advantage over us due to their size, capital resources and greater clinical development or commercialization capabilities. In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. As a result, we may be unable to obtain any such licenses at a reasonable cost or on reasonable terms, if at all. In that event, we may be required to expend significant time and resources to redesign our technology, product candidates, or the methods for manufacturing them, or to develop or license replacement technology, all of which may not be feasible on a technical or commercial basis. If we are unable to do so, we may be unable to develop or commercialize the affected product candidates, which could harm our business, financial condition, results of operations, and prospects significantly. In addition, even if we obtain a license, it may be non-exclusive, thereby giving our competitors access to the same technologies licensed to us, and it could require us to make substantial licensing and royalty payments, which could have a material adverse effect on our business, financial condition, results of operations, and prospects.

Moreover, some of our owned and in-licensed patents and patent applications are, and may in the future be, co-owned with third parties. If we are unable to obtain an exclusive license to any such third-party co-owners’ interest in such patents or patent applications, such co-owners may license their rights to other third parties, including our competitors, and such third parties could market competing products and technology. In addition, we may need the cooperation of any such co-owners of our patents in order to enforce such patents against third parties, and such cooperation may not be provided to us. Any of the foregoing could have a material adverse effect on our competitive position, business, financial conditions, results of operations, and prospects.

Third parties may initiate legal proceedings against us alleging that we infringe, misappropriate, or otherwise violate their intellectual property rights, or we may initiate legal proceedings against third parties to challenge the validity or scope of intellectual property rights controlled by third parties, the outcome of which would be uncertain and could have an adverse effect on the success of our business.

Our commercial success depends upon our ability to develop, manufacture, market and sell our product candidates and use our and our current or future licensors’ proprietary technologies without infringing, misappropriating, or otherwise violating the intellectual property rights of third parties. The biotechnology and pharmaceutical industries are characterized by extensive litigation regarding patents and other intellectual property rights. Third parties may initiate legal proceedings against us or our current and future licensors alleging that we or our current and future licensors infringe, misappropriate, or otherwise violate their intellectual property rights. In addition, we or our current and future licensors may initiate legal proceedings against third parties to challenge the validity or scope of intellectual property rights controlled by third parties, including in oppositions, interferences, reexaminations, inter partes reviews, or derivation proceedings in the United States or

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other jurisdictions. These proceedings can be expensive and time-consuming, and many of our or our current and future licensors’ adversaries in these proceedings may have the ability to dedicate substantially greater resources to prosecuting these legal actions than we or our current and future licensors.

There are third-party patents and, if issued as patents, patent applications relating to the engineering of antibodies, including with respect to CD40 and Fc domains, that may be construed to cover our product candidates, including sotigalimab. The third parties that control these patents may allege that our product candidates, including sotigalimab, infringe these patents. Parties making infringement, misappropriation, or other intellectual property claims against us may obtain injunctive or other equitable relief, which could effectively block our ability to further develop and commercialize one or more of our product candidates. Defense of these claims, regardless of their merit, would involve substantial litigation expense and would be a substantial diversion of management and employee resources from our business. In addition, even if we believe any third-party intellectual property claims are without merit, there is no assurance that a court would find in our favor on questions of validity, enforceability, priority, or non-infringement. A court of competent jurisdiction could hold that such third-party patents are valid, enforceable, and infringed, which could materially and adversely affect our ability to commercialize any of our products or technologies covered by the asserted third-party patents. In order to successfully challenge the validity of any such third-party U.S. patents in federal court, we would need to overcome a presumption of validity. As this burden is a high one requiring us to present clear and convincing evidence as to the invalidity of any such U.S. patent claim, there is no assurance that a court of competent jurisdiction would invalidate the claims of any such U.S. patent. An unfavorable outcome could require us or our current and future licensors to cease using the related technology or developing or commercializing our product candidates, or to attempt to license rights to it from the prevailing party. Our business could be harmed if the prevailing party does not offer us or our current and future licensors a license on commercially reasonable terms or at all. Even if we or our current and future licensors obtain a license, it may be non-exclusive, thereby giving our competitors access to the same technologies licensed to us or our current and future licensors, and it could require us to make substantial licensing and royalty payments. In addition, we could be found liable for monetary damages, including treble damages and attorneys’ fees, if we are found to have willfully infringed a patent. A finding of infringement, misappropriation, or other violation of third-party intellectual property could prevent us from commercializing our product candidates or force us to cease some of our business operations, which could harm our business. Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar material adverse effect on our business, financial condition, results of operations, and prospects.

We may be subject to claims by third parties asserting that we or our employees, consultants, or advisors have misappropriated their intellectual property, or claiming ownership of what we regard as our own intellectual property.

Many of our employees, consultants, and advisors, including our senior management, were previously employed at other biopharmaceutical companies, including our competitors or potential competitors. Some of these employees executed proprietary rights, non-disclosure, and/or non-competition agreements in connection with such previous employment. Although we try to ensure that our employees, consultants, and advisors 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 individuals have used or disclosed confidential information or intellectual property, including trade secrets or other proprietary information, of any such individual’s current or former employer. Litigation may be necessary to defend against these claims. If we fail in prosecuting or defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Such intellectual property rights could be awarded to a third party, and we could be required to obtain a license from such third party to commercialize our technology or products. Such a license may not be available on commercially reasonable terms, or at all. Even if we successfully prosecute or defend against such claims, litigation could result in substantial costs and distract management.

In addition, while it is our policy to require our employees and contractors who may be involved in the conception or development of intellectual property to execute agreements assigning such intellectual property to

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

Our inability to protect our confidential information and trade secrets would harm our business and competitive position.

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. Trade secrets can be difficult to protect. 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, CROs, contract manufacturers, consultants, advisors, and other third parties. We also enter into confidentiality agreements with our employees and consultants. We cannot guarantee that we have entered into such agreements with each party that may have or have had access to our trade secrets or proprietary technology and processes. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not obtain adequate remedies for such breaches. Misappropriation or unauthorized disclosure of our trade secrets could significantly affect our competitive position and may have a material adverse effect on our business. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. Some courts both within and outside the United States may be less willing or unwilling to protect trade secrets. Furthermore, trade secret protection does not prevent competitors from independently developing substantially equivalent information and techniques and we cannot guarantee that our competitors will not independently develop substantially equivalent information and techniques. If a competitor lawfully obtained or independently developed any of our trade secrets, we would have no right to prevent such competitor from using that technology or information to compete with us. Failure on our part to adequately protect our trade secrets and our confidential information would harm our business and our competitive position.

Issued patents covering one or more of our product candidates or technologies could be found invalid or unenforceable if challenged in court.

To protect our competitive position, we may from time to time need to resort to litigation in order to enforce or defend any patents or other intellectual property rights owned by or licensed to us, or to determine or challenge the scope or validity of patents or other intellectual property rights of third parties. Enforcement of intellectual property rights is difficult, unpredictable, and expensive, and many of our or our licensors’ or collaboration partners’ adversaries in these proceedings may have the ability to dedicate substantially greater resources to prosecuting these legal actions than we or our licensors or collaboration partners can. Accordingly, despite our or our licensors’ or collaboration partners’ efforts, we or our licensors or collaboration partners may not prevent third parties from infringing upon or misappropriating intellectual property rights we own or control, particularly in countries where the laws may not protect those rights as fully as in the European Union and the United States. We may fail in enforcing our rights—in which case our competitors may be permitted to use our technology without being required to pay us any license fees. In addition, however, litigation involving our patents carries the risk that one or more of our patents will be held invalid (in whole or in part, on a claim-by-claim basis) or held unenforceable. Such an adverse court ruling could allow third parties to commercialize our products or use our technologies, including our APXiMAB platform, and then compete directly with us, without payment to us.

If we or one of our licensors were to initiate legal proceedings against a third party to enforce a patent covering one of our products, the defendant could counterclaim that such patent is invalid or unenforceable. In patent litigation in the United States or in Europe, defendant counterclaims alleging invalidity or unenforceability are commonplace. A claim for a validity challenge may be based on failure to meet any of several statutory

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requirements, for example, lack of novelty, obviousness, or non-enablement. A claim for unenforceability could involve an allegation that someone connected with prosecution of the patent withheld relevant information from the European Patent Office or the USPTO or made a misleading statement, during prosecution. Third parties may also raise similar claims before the USPTO or an equivalent foreign body, even outside the context of litigation. Potential proceedings include re-examination, post-grant review, inter partes review, interference proceedings, derivation proceedings, and equivalent proceedings in foreign jurisdictions (e.g., opposition proceedings). Such proceedings could result in the revocation of, cancellation of, or amendment to our patents in such a way that they no longer cover our technology or any product candidates that we may develop. The outcome following legal assertions of invalidity and unenforceability during patent litigation is unpredictable. With respect to the validity question, for example, we cannot be certain that there is no invalidating prior art, of which we or our licensing partners and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity or unenforceability, we would lose at least part, and perhaps all, of the patent protection on one or more of our product candidates or certain aspects of our APXiMAB platform technologies. Such a loss of patent protection could have a material adverse impact on our business, financial condition, results of operations, and prospects. Further, litigation could result in substantial costs and diversion of management resources, regardless of the outcome, and this could harm our business and financial results. Patents and other intellectual property rights also will not protect our technology if competitors design around our protected technology without infringing our patents or other intellectual property rights.

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

Competitors and other third parties may infringe, misappropriate, or otherwise violate our issued patents or other intellectual property or the patents or other intellectual property of our licensors, or we or our licensors may be required to defend against claims of infringement, misappropriation, or other violation. In addition, our patents or the patents of our licensors may become involved in inventorship or priority disputes. Other disputes may arise related to intellectual property rights that we believe are derived from, or related to, our patents or technology, including with respect to sotigalimab. For example, Apexigen is aware of certain patent applications filed by a former collaborator covering biomarkers and patient selection discoveries related to our sotiga program. Apexigen believes that we own the intellectual property covered by these provisional patent applications. We are in discussions with the former collaborator to assign their rights in this intellectual property to us, but there is no guarantee that we will come to a satisfactory resolution of this matter.

To counter infringement, misappropriation, or other unauthorized use, we or our licensors may be required to negotiate a solution to such dispute or file infringement claims, either of which can be expensive and time-consuming. Any claims we or our licensors assert against perceived infringers could provoke these parties to assert counterclaims against us or our licensors alleging that we or our licensors infringe their patents or that our or our licensors’ patents are invalid or unenforceable. In a patent infringement proceeding, a court may decide that a patent of ours or one of our licensors’ is invalid or unenforceable, in whole or in part, construe the patent’s claims narrowly or refuse to stop the other party from using the technology at issue on the grounds that our or our licensors’ patents do not cover the technology. An adverse result in any litigation proceeding could put one or more of our owned or licensed patents at risk of being invalidated, held unenforceable, or interpreted narrowly.

We may find it impractical or undesirable to enforce our intellectual property against some third parties. 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.

Interference proceedings provoked by third parties or brought by us or declared by the USPTO may be necessary to determine the priority of inventions with respect to our or our licensors’ patents or patent applications. If we or our licensors are unsuccessful in any interference proceedings to which we or they are subject, we may lose

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valuable intellectual property rights through the loss of one or more patents owned or licensed or our owned or licensed patent claims may be narrowed, invalidated, or held unenforceable. If we or our licensors are unsuccessful in any interference proceeding or other priority or inventorship dispute, we may be required to obtain and maintain licenses from third parties, including parties involved in any such interference proceedings or other priority of inventorship disputes. Such licenses may not be available on commercially reasonable terms or at all, or may be non-exclusive. If we are unable to obtain and maintain such licenses, we may need to cease the development, manufacture, and commercialization of one or more of the product candidates we may develop. The loss of exclusivity or narrowing of our owned or licensed patent claims could limit our ability to stop others from using or commercializing similar or identical technology and products.

Any of the foregoing intellectual property disputes or litigation could result in a material adverse effect on our business, financial condition, results of operations, or prospects.

Intellectual property litigation or proceedings could cause us to spend substantial resources and distract our personnel.

Even if resolved in our favor, litigation or other legal proceedings relating to intellectual property claims could result in substantial costs and diversion of management resources, which could harm our business. In addition, the uncertainties associated with litigation could compromise our ability to raise the funds necessary to continue our clinical trials, continue our internal research programs or in-license needed technology or other product candidates. There could also be public announcements of the results of the hearing, motions or other interim proceedings or developments. If securities analysts or investors perceive those results to be negative, it could cause the price of shares of our common stock to decline. Such litigation or proceedings could substantially increase our operating losses and reduce the resources available for development activities or any future sales, marketing, or distribution activities. We may not have sufficient financial or other resources to conduct such litigation or proceedings adequately. Most of our competitors are larger than we are and have substantially greater resources. They are, therefore, likely to sustain the costs of complex patent litigation or proceedings more effectively than we can because of their greater financial resources and more mature and developed intellectual property portfolios. Accordingly, despite our efforts, we may not prevent third parties from infringing upon, misappropriating, or otherwise violating our intellectual property. Any of the foregoing events could harm our business, financial condition, results of operations, and prospects.

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

Patents have a limited lifespan. Due to the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our owned and licensed patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours. In the United States, if all maintenance fees are timely paid, the natural expiration of a patent is generally 20 years from its earliest U.S. filing date. Various extensions may be available, but the life of a patent, and the protection it affords, is limited. Even if patents covering our product candidates are obtained, once the patent life has expired for a product, we may be open to competition from competitive medications, including biosimilar or generic medications. For example, certain of our owned patents that cover sotigalimab will begin to expire in 2032, absent extensions, in the United States and similar patent applications are pending in foreign jurisdictions. At the time of the expiration of the relevant patents, the underlying technology covered by such patents can be used by any third party, including competitors. Although the patent term extensions under the Drug Price Competition and Patent Term Restoration Action of 1984 (“Hatch-Waxman Act”) in the United States may be available to extend the patent term, we cannot provide any assurances that any such patent term extension will be obtained and, if so, for how long.

Depending upon the timing, duration and specifics of any FDA marketing approval of any product candidates we may develop, one or more of our U.S. patents may be eligible for limited patent term extension under the

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Hatch-Waxman Act. The Hatch-Waxman Act permits a patent term extension of up to five years as compensation for patent term lost during the FDA regulatory review process. A patent term extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval, only one patent may be extended, and only those claims covering the approved drug, a method for using it, or a method for manufacturing it may be extended. However, we may not be granted an extension because of, for example, failing to exercise due diligence during the testing phase or regulatory review process, failing to apply within applicable deadlines, failing to apply prior to expiration of relevant patents, or otherwise failing to satisfy applicable requirements. Moreover, the applicable time period or the scope of patent protection afforded could be less than we request. If we are unable to obtain patent term extension or term of any such extension is less than we request, our competitors may obtain approval of competing products following our patent expiration, and our business, financial condition, results of operations, and prospects could be materially harmed.

If our trademark and tradenames are not adequately protected, then we may not build name recognition in our markets and our business may be adversely affected.

We cannot assure you that competitors will not infringe our trademarks or that we will have adequate resources to enforce our trademarks. We cannot assure you that any future trademark applications that we will file will be approved. During trademark registration proceedings, we may receive rejections and although we are given an opportunity to respond to those rejections, we may be unable to overcome such rejections. In addition, in proceedings before the USPTO and in proceedings before comparable agencies in many foreign jurisdictions, third parties are given an opportunity to oppose pending trademark applications and to seek to cancel registered trademarks. An opposition or cancellation proceeding may be filed against our trademarks and our trademarks may not survive such proceedings, which may force us to rebrand our name.

Intellectual property rights do not necessarily address all potential threats.

The degree of future protection afforded by our intellectual property rights is uncertain because intellectual property rights have limitations and may not adequately protect our business or permit us to maintain our competitive advantage. For example:

• others may make products that are similar to any product candidates we may develop or utilize similar technology but that are not covered by the claims of the patents that we license or may own in the future;

• others may independently develop similar or alternative technologies or duplicate any of our technologies without infringing our owned or licensed intellectual property rights;

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

• we may not develop additional proprietary technologies that are patentable; and

• we may choose not to file a patent in order to maintain certain trade secrets or know-how, and a third party may subsequently file a patent covering such intellectual property.

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

Risks Related to Our Dependence on Third Parties

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, research and studies.

We do not have the ability to independently conduct our clinical trials. Apexigen currently relies on third parties to conduct clinical trials of its product candidates, including ISTs sponsored by third parties; these third parties

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also include CROs, clinical data management organizations, medical institutions and clinical investigators. We expect to continue to rely upon third parties to conduct additional clinical trials of our product candidates. Third parties have a significant role in the conduct of our clinical trials and the subsequent collection and analysis of data. These third parties are not our employees, and except for remedies available to us under our agreements, we have limited ability to control the amount or timing of resources that any such third party will devote to our clinical trials. In some cases, these third parties may not provide us with information about the ongoing clinical trials on a timely basis. The third parties may also violate the terms of the agreements governing such clinical trials in various ways, including asserting intellectual property rights that contractually belong to Apexigen. Some of these third parties may terminate their engagements with us at any time. If we need to enter into alternative arrangements, it would delay our drug development activities.

Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our regulatory responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial. Moreover, the FDA requires us to comply with GCP standards, regulations for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity, and confidentiality of trial participants are protected. The EMA also requires us to comply with similar standards. Regulatory authorities enforce these GCP requirements through periodic inspections of trial sponsors, principal investigators, and trial sites. If we or any of our CROs fail to comply with applicable GCP requirements, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, EMA, or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP regulations. In addition, our clinical trials must be conducted with product produced under current GMP regulations. Our failure or the failure of the third parties we engage to comply with these regulations may require us to repeat clinical trials, which would delay the marketing approval process. We also are required to register certain ongoing clinical trials and post the results of certain completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within certain timeframes. Failure to do so can result in fines, adverse publicity, and civil and criminal sanctions.

The third parties we rely on for these services 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 obtain, or may be delayed in obtaining, marketing approvals for our product candidates and will not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates.

We contract with third parties for the production of sotigalimab and our other product candidates for preclinical studies and our ongoing clinical trials, and expect to continue to do so for additional clinical trials and ultimately for commercialization and for additional product candidates. This reliance on third parties increases the risk that we will not have sufficient quantities of our product candidates or drugs or such quantities at an acceptable cost, which could delay, prevent, or impair our development or commercialization efforts.

We do not currently have the infrastructure or internal capability to manufacture our product candidates for use in clinical development and commercialization. We rely, and expect to continue to rely, on third-party manufacturers for the production of our product candidates in compliance with GMP requirements for clinical trials under the guidance of members of our organization. Apexigen currently relies on a single third-party manufacturer, WuXi Biologics (Hong Kong) Limited (“WuXi”), for the manufacture of our product candidates sotiga and APX601. We expect the quantity and stability of our current supply of sotiga from that prior manufacturer will be sufficient to supply our currently ongoing clinical trials through mid-2023. We plan to undertake our first drug substance manufacturing run at WuXi in mid-2022. If WuXi successfully manufactures sotiga and the FDA and other relevant regulatory authorities approve our comparability protocol, we expect to

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have sotiga drug product ready for clinical use by mid-2023. If WuXi experiences delays in manufacturing or does not successfully manufacture sotiga or the FDA or other relevant regulatory authorities do not accept our comparability protocol, we may run out of sotiga drug product to supply the clinical development of sotiga by mid-2023.

The manufacture of biologic therapeutics is complex. It is anticipated that during development from early clinical trials to commercialization that changes to the manufacturing cell line, manufacturing process or analytical methods will occur. These changes carry the risk that the intended goals of such changes are not achievable and that further development work may be needed to reach these goals, which may delay our ability to meet clinical or commercial supply needs. Our change in the manufacturing site, cell line, process and analytical methods for sotiga represent a specific elevated risk for the sotiga program. However, Apexigen currently has no alternative manufacturer in place for sotiga and APX601 drug substance and drug product. For the APX601 product candidate, we have successfully completed drug substance runs at WuXi and expect to have APX601 clinical material ready for use in the second half of 2022.

If we were to experience an unexpected loss of supply of our product candidates for any reason, whether as a result of manufacturing, supply, or storage issues or otherwise, we could experience delays, disruptions, suspensions or terminations of, or be required to restart or repeat, any pending or ongoing clinical trials, such as occurred with the prior switchover by Apexigen to a new contract manufacturer. Replacement of our sole manufacturer would likely result in substantial delay and could interrupt our clinical trials if we had not previously obtained enough supply of our product candidates.

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

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

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

• the possible failure of our third-party manufacturer to procure raw materials from third-party suppliers and potential exposure to supply chain issues impacting delivery dates, quality, quantity and pricing of raw materials, including due to the COVID-19 pandemic, which may result in additional costs and delays in production of clinical trial materials, commercial product and regulatory approvals;

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

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

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

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

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

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

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We do not have control over many aspects of the manufacturing process of, and are dependent on, our contract manufacturing partners, including WuXi, for compliance with GMP regulations for manufacturing both active drug substances and finished drug products. Third-party manufacturers may not be able to comply with U.S. export control regulations, GMP regulations or similar regulatory requirements outside of the United States. If our contract manufacturers cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA, EMA, or others, they will not secure and/or maintain marketing approval for their manufacturing facilities. In addition, we do not have control over the ability of our contract manufacturers to maintain adequate quality control, quality assurance, and qualified personnel. If the FDA, EMA or a comparable foreign regulatory authority does not approve these facilities for the manufacture of our product candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would significantly impact our ability to develop, obtain marketing approval for, or market our product candidates, if approved. Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of product candidates or drugs, operating restrictions, and criminal prosecutions, any of which could significantly and adversely affect supplies of our drugs and harm our business and results of operations.

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

We may not gain the efficiencies we expect from further scale-up of manufacturing of our product candidates, and our third-party manufacturers may be unable to successfully scale up manufacturing in sufficient quality and quantity for our product candidates, which could delay or prevent the conducting of our clinical trials or the development or commercialization of our other product candidates.

We expect that our third-party manufacturer, WuXi, will manufacture our product candidates at a scale and on a timeline that is sufficient for us to complete our planned clinical trials and, if we receive marketing approval, to commercialize our product candidates, including sotigalimab, for the indications we are currently targeting. However, we may consider increasing the batch scale to gain cost efficiencies. If our current manufacturer or any other manufacturer we use is unable to scale-up the manufacture of our product candidates at such time, we may not gain such cost efficiencies and may not realize the benefits that would typically be expected from further scale-up of manufacturing. In addition, quality or other technical issues may arise during scale-up activities. If our third-party manufacturers are unable to successfully scale up the manufacture of our product candidates in sufficient quality and quantity, the development, testing and clinical trials of that product candidate may be delayed or become infeasible, and marketing approval or commercial launch of any resulting product may be delayed or not obtained, which could significantly harm our business.

Changes in methods of product candidate manufacturing or formulation may result in additional costs or delay.

As product candidates progress through preclinical and late-stage clinical trials to marketing approval and commercialization, it is common that various aspects of the development program, such as manufacturing methods and formulation, are altered along the way in an effort to optimize yield, manufacturing batch size, minimize costs and achieve consistent quality and results. Such changes carry the risk that they will not achieve these intended objectives. Any of these changes could cause our product candidates to perform differently and affect the results of planned clinical trials or other future clinical trials conducted with the altered materials. The FDA may not approve our third-party manufacturers’ processes or facilities. This could delay completion of clinical trials, require the conduct of bridging clinical trials or the repetition of one or more clinical trials, increase clinical trial costs, delay approval of our product candidates, and jeopardize our ability to commercialize our product candidates and generate revenue.

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We have and may in the future enter into additional agreements with third parties under which those parties have or will be granted a license to develop product candidates discovered using our APXiMAB platform. If any such programs are not successful or if disputes arise related to such programs, we may not realize the full commercial benefits from such programs.

Our APXiMAB platform has enabled the discovery of several product candidates with potential utility in multiple therapeutic areas and has resulted in five programs that have been licensed to third parties, including larger global biopharmaceutical companies and mid-sized regional or China-focused companies. Our likely counterparties for future licensing and collaboration arrangements include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies, and biotechnology companies. Such arrangements generally allow the licensing parties to control the amount and timing of resources that they dedicate to the development or potential commercialization of any product candidates they develop from the technology we have licensed to them, subject to any territorial or field of use restrictions in the license. In addition, Apexigen partnered with ESBATech AG, which was acquired by Alcon and later Novartis to provide rabbit monoclonal antibodies in order to develop product candidates for certain diseases.

We typically negotiate milestone payments and royalty fees from our licensees that will require various levels of success with their product candidate development program in order for us to generate revenue from them. Our ability to generate revenue from these licensing arrangements will depend on our counterparties’ abilities to successfully develop and commercialize the product candidates they are developing. We cannot predict the success of any licensing program that we enter into or whether such program will lead to any meaningful milestone or royalty revenue to us.

Licensing programs involving third-party development of product candidates derived from our licensed technology pose the following risks to us:

• counterparties generally have significant discretion, if not total control, in determining the efforts and resources that they will apply to these development efforts;

• counterparties may not properly or adequately obtain, maintain, enforce, or defend intellectual property or proprietary rights relating to our intellectual property or may use our proprietary information in such a way as to expose us to potential litigation or other intellectual property-related proceedings, including proceedings challenging the scope, ownership, validity, and enforceability of our intellectual property;

• counterparties may own or co-own with us intellectual property covering their product candidates, and, in such cases, we typically will not have the exclusive right to commercialize such intellectual property or their product candidates based on the terms of the licensing agreement;

• we may need the cooperation of these counterparties to enforce or defend any intellectual property we contribute to the program;

• counterparties typically will control the interactions with regulatory authorities related to their product candidates, which may impact our ability to obtain and maintain regulatory approval of our own product candidates;

• disputes may arise between the counterparties and us that result in the delay or termination of the research, development, or commercialization of our product candidates or research programs or that result in costly litigation or arbitration that diverts management attention and resources;

• counterparties may decide to not pursue development and commercialization of any product candidates that are derived from our licensed technology, or may elect not to continue or renew development or commercialization programs based on clinical trial results, changes in the counterparties’ strategic focus or available funding or external factors such as an acquisition that diverts resources or creates competing priorities, or counterparties may elect to fund or commercialize a competing product;

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• counterparties could independently develop, or develop with third parties, products that compete directly or indirectly with our product candidates or research programs if the collaborators believe that competitive products are more likely to be successfully developed or can be commercialized under terms that are more economically attractive than ours;

• counterparties may not commit sufficient resources to the marketing and distribution of their product candidates, resulting in lower royalties to us;

• counterparties may grant sublicenses to our technology or undergo a change of control, and the sublicensees or new owners may decide to pursue a strategy with respect to the program which is not in our best interest;

• counterparties may become bankrupt, which may significantly delay our research or development programs, or may cause us to lose access to valuable technology, know-how, or intellectual property of the counterparty relating to our technology in relation to the terms of the licensing agreement;

• if these counterparties do not satisfy their obligations under our agreements with them, or if they terminate our licensing agreements with them, we may be adversely impacted; and

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

Beovu® is a drug product developed by Novartis covered under the ESBATech Agreement with Apexigen. Novartis obtained approval for Beovu for use in neovascular (wet) age-related macular degeneration (“AMD”) and as a treatment of visual impairment due to diabetic macular edema, Novartis continues to develop Beovu for other indications. Under the terms of the ESBATech agreement, Novartis is obligated to pay Apexigen a very low single-digit royalty on worldwide net sales of Beovu. However, Novartis has disputed its obligation to pay royalties to Apexigen under the agreement and continues to pay such royalties under protest. As a result, Apexigen has determined that any sales-based royalties received from Novartis for Beovu are currently fully constrained, and Apexigen has recorded the royalty proceeds as deferred revenue on its balance sheet, with the amounts totaling $3.6 million and $4.6 million as of December 31, 2021 and June 30, 2022, respectively. If the dispute with Novartis regarding their royalty obligations is not settled favorably through negotiation or if the parties escalate the dispute through arbitration or litigation, there is no guarantee that we will recognize such historic and future royalty revenue in part or at all, we may be required to return the cash received to date for the constrained royalty payments, we may not receive future payments, and we may incur substantial costs and distraction of management related to such dispute. While this dispute continues, the Beovu royalty rights will be impaired which will limit our ability to exercise ownership over or monetize this royalty stream, all of which could have an adverse effect on our business, financial condition, and results of operations.

Many of the risks relating to product development, intellectual property, regulatory approval, and commercialization described in this “Risk Factors” section also apply to the activities of our licensees and any negative impact on these counterparties and their product development programs may adversely affect us.

If we seek to establish additional collaborations, but are unable to do so, 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. We may seek to selectively form collaborations to expand our capabilities, potentially accelerate research and development activities, and provide for commercialization activities by third parties.

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

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number of factors. Those factors may include the design or results of clinical trials, the likelihood of approval by the FDA, EMA, or comparable foreign regulatory authorities, 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 drugs, the existence of uncertainty with respect to our ownership of intellectual property and industry and market conditions generally. The potential 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.

Collaborations are complex and time-consuming to negotiate and document. 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. Even if we successfully enter into a collaboration, the terms and conditions of that collaboration may restrict us from entering into future agreements on certain terms with potential collaborators.

If and when we seek to enter into collaborations, we may not negotiate collaborations on a timely basis, on acceptable terms, or at all. If we are unable to do so, we may have to curtail the development of a 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 engage in acquisitions or strategic partnerships or collaborations, this may increase our capital requirements, dilute our stockholders, cause us to incur debt or assume contingent liabilities, and subject us to other risks.

We may evaluate various acquisition opportunities and strategic partnerships or collaborations, including licensing or acquiring complementary products, intellectual property rights, technologies or businesses. Any potential acquisition or strategic partnership may entail numerous risks, including:

• exposure to unknown liabilities;

• increased operating expenses and cash requirements;

• the assumption of additional indebtedness or contingent liabilities;

• the issuance of our equity securities;

• assimilation of operations, intellectual property, and products of an acquired company, including costs and difficulties associated with integrating new personnel;

• the diversion of our management’s attention from our existing product programs and initiatives in pursuing such a strategic merger or acquisition;

• retention of key employees, the loss of key personnel, and uncertainties in our ability to maintain key business relationships;

• impairment of relationships with key collaborators and other counterparties of any acquired businesses due to changes in management and ownership;

• risks and uncertainties associated with the other party to such a transaction, including the prospects of that party and their existing products or product candidates and marketing approvals; and

• our inability to generate revenue from acquired technology and/or products sufficient to meet our objectives in undertaking the acquisition or even to offset the associated acquisition and maintenance costs.

In addition, if we undertake acquisitions, we may issue dilutive securities, assume or incur debt obligations, incur large one-time expenses, and acquire intangible assets that could result in significant future amortization expense.

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Moreover, we may not locate suitable acquisition opportunities, and this inability could impair our ability to grow or obtain access to technology or products that may be important to the development of our business.

Other General Risks

The COVID-19 pandemic could adversely impact our business including our ongoing and planned clinical trials and preclinical research.

Over two years after the World Health Organization declared the novel coronavirus disease (“COVID-19”) a pandemic, the COVID-19 pandemic continues to impact worldwide economic activity and financial markets. Variants of COVID-19 have caused and may continue to cause waves of increased infections. As a result of measures imposed by the governments in affected regions, many commercial activities, businesses and schools have been affected by quarantines and other measures intended to contain the pandemic and subsequent variants of the COVID-19 virus. The extent to which the COVID-19 pandemic ultimately impacts our business will depend on future developments, which are highly uncertain and cannot be predicted, such as the duration of the outbreak, including current and subsequent variants of COVID-19, travel restrictions and social distancing in the United States and other countries, business closures or business disruptions, and the effectiveness of actions taken in the United States and other countries to contain and treat the disease and to address its impact, including on financial markets or otherwise. As the COVID-19 pandemic continues, we may experience disruptions that could severely impact our business, current and planned clinical trials and preclinical research, including:

• delays or difficulties in enrolling and retaining subjects, including elderly subjects, who are at a higher risk of severe illness or death from COVID-19, in our ongoing clinical trials and our future clinical trials;

• delays or difficulties in clinical site initiation, including due to difficulties in staffing and recruiting at clinical sites;

• difficulties interpreting data from our clinical trials due to the possible effects of COVID-19 on subjects;

• diversion of healthcare resources away from the conduct of clinical trials, including the diversion of hospitals serving as our clinical trial sites and hospital staff supporting the conduct of clinical trials;

• interruption of key clinical trial activities, such as clinical trial site monitoring, due to limitations on travel imposed or recommended by federal or state governments, employers and others;

• limitations in resources, including our employees, that would otherwise be focused on the conduct of our business or our current or planned clinical trials or preclinical research, including because of sickness, the desire to avoid contact with large groups of people, or restrictions on movement or access to our facility as a result of government-imposed “shelter in place” or similar working restrictions;

• interruptions, difficulties or delays arising in our existing operations and company culture as a result of some or all of our employees working remotely, including those hired during the COVID-19 pandemic;

• delays in receiving approval from regulatory authorities to initiate our clinical trials;

• interruptions in preclinical studies due to restricted or limited operations at the CROs conducting such studies;

• interruptions or delays in the operations of the FDA or other domestic or foreign regulatory authorities, which may impact review and approval timelines;

• delays in receiving the supplies, materials and services needed to conduct clinical trials and preclinical research;

• changes in regulations as part of a response to the COVID-19 pandemic which may require us to change the ways in which our clinical trials are conducted, which may result in unexpected costs or require us to discontinue the clinical trial altogether;

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• interruptions or delays to our development pipeline;

• delays in necessary interactions with regulators, ethics committees and other important agencies and contractors due to limitations in employee resources or forced furlough of government or contractor personnel; and

• refusal of the FDA to accept data from clinical trials in affected geographies outside of the United States.

The COVID-19 pandemic continues to pose a threat on our ability to effectively conduct our business operations as planned and there can be no assurance that we will avoid a material impact on our business from the spread of COVID-19 or its consequences, including disruption to our business and downturns in business sentiment generally or in our industry or due to shutdowns that may be requested or mandated by federal, state and local governmental authorities.

Additionally, certain third parties with whom we engage or may engage, including collaborators, contract organizations, third-party manufacturers, suppliers, clinical trial sites, regulators and other third parties are similarly adjusting their operations and assessing their capacity in light of the COVID-19 pandemic. If these third parties experience shutdowns or continued business disruptions, our ability to conduct our business in the manner and on the timelines presently planned could be materially and negatively impacted. For example, as a result of the COVID-19 pandemic, there could be delays in the procurement of materials or manufacturing supply chains for one or more of our product candidates, which could delay or otherwise impact our preclinical studies and our planned clinical trials. Additionally, all of our preclinical studies are conducted by CROs, which could be discontinued or delayed as a result of the pandemic. It is also likely that the disproportionate impact of COVID-19 on hospitals and clinical sites will have an impact on recruitment and retention for our planned clinical trials. CROs have also made certain adjustments to the operation of such trials in an effort to ensure the monitoring and safety of patients and minimize risks to trial integrity during the pandemic in accordance with the guidance issued by the FDA and may need to make further adjustments in the future that could impact the timing or enrollment of our clinical trials. Many of these adjustments are new and untested, may not be effective, may increase costs and may have unforeseen effects on the enrollment, progress and completion of these trials and the findings from these trials. While we are currently continuing our clinical trials and preclinical studies, we may experience delays in the completion of our clinical trials, preclinical activities and subject enrollment, may need to suspend our clinical trials and may encounter other negative impacts to such trials due to the effects of the COVID-19 pandemic.

Further, as a result of the COVID-19 pandemic, the extent and length of which is uncertain, we may be required to develop and implement additional clinical trial policies and procedures designed to help protect subjects from the COVID-19 virus, which may include using telemedicine visits, remote monitoring of subjects and clinical sites and measures to ensure that data from clinical trials that may be disrupted as a result of the pandemic are collected pursuant to the study protocol and consistent with GCPs. Subjects who may miss scheduled appointments, any interruption in study drug supply, or other consequences that may result in incomplete data being generated during a clinical trial as a result of the pandemic must be adequately documented and justified. For example, in March 2020, the FDA issued a guidance, which the FDA subsequently updated, on conducting clinical trials during the pandemic, which describes a number of considerations for sponsors of clinical trials impacted by the pandemic, including the requirement to include in the clinical trial report contingency measures implemented to manage the trial, and any disruption of the trial as a result of the COVID-19 pandemic; a list of all subjects affected by the COVID-19-pandemic related study disruption by unique subject identifier and by investigational site and a description of how the individual’s participation was altered; and analyses and corresponding discussions that address the impact of implemented contingency measures (e.g., participant discontinuation from investigational product and/or study, alternative procedures used to collect critical safety and/or efficacy data) on the safety and efficacy results reported for the clinical trial. In June 2020, the FDA also issued a guidance on good manufacturing practice considerations for responding to COVID-19 infection in employees in drug product manufacturing, including recommendations for manufacturing controls to prevent contamination of drugs.

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The COVID-19 pandemic continues to evolve. While the extent of the impact of the COVID-19 pandemic on our business and financial results is uncertain, a continued and prolonged public health crisis such as the COVID-19 pandemic could have a material negative impact on our business, financial condition and operating results.

To the extent the COVID-19 pandemic adversely affects our business and financial results, it may also have the effect of heightening many of the other risks described in this section and in this “Risk Factors” section.

Our internal computer systems, or those used by our third-party research institution collaborators, other contractors, or consultants, may fail or suffer other breakdowns, cyberattacks or information security breaches that could compromise the confidentiality, integrity and availability of such systems and data, result in material disruptions of our development programs and business operations, risk disclosure of confidential, financial or proprietary information, and affect our reputation.

Despite the implementation of security measures, our internal computer systems or those used by our third-party research institution collaborators, other contractors, or consultants, may be vulnerable to damage from computer viruses and unauthorized access. As the cyber-threat landscape evolves, attacks are growing in frequency, sophistication, and intensity, and are becoming increasingly difficult to detect. These risks are increased given the recent work from home arrangements because of the COVID-19 pandemic and the threats of Russian cyberattacks in response to the war in Ukraine. Such attacks could include the use of key loggers or other harmful and virulent malware, including ransomware or other denials of service, and can be deployed through malicious websites, the use of social engineering, and/or other means. If a breakdown, cyberattack, or other information security breach were to occur and cause interruptions in our operations, it could result in a misappropriation of confidential information, including our intellectual property or financial information, and a material disruption of our development programs and our business operations. For example, the loss of clinical trial data from completed, ongoing, or future clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. Likewise, we rely on our third-party research institution collaborators for research and development of our product candidates and other third parties for the manufacture of our product candidates and to conduct clinical trials, and similar events relating to their computer systems could also have a material adverse effect on our business. To the extent that any disruption or security breach were to result in a loss of, or damage to, our data or systems, or inappropriate disclosure of confidential, financial, or proprietary information, including data related to our personnel, we could incur liability or risk disclosure of confidential, financial, or proprietary information, and the further development and commercialization of our product candidates could be delayed. There can be no assurance that we and our business counterparties will be successful in efforts to detect, prevent, or fully recover systems or data from all breakdowns, service interruptions, attacks, or breaches of systems that could adversely affect our business and operations and/or result in the loss of critical or sensitive data, which could result in financial, legal, business, or reputational harm to us.

Our operations are subject to the effects of a rising rate of inflation.

The United States has recently experienced historically high levels of inflation. According to the U.S. Department of Labor, the annual inflation rate for the United States was approximately 8.5% for the 12 months ended July 31, 2022. If the inflation rate continues to increase, for example due to increases in the costs of labor and supplies, it will affect our expenses, such as employee compensation and research and development charges. Research and development expenses account for a significant portion of our operating expenses. Such increased charges may not be readily recoverable during the period of time that we are bringing the product candidates to market. Additionally, the United States is experiencing an acute workforce shortage, which in turn, has created a very competitive wage environment that may increase the Company’s operating costs. To the extent inflation results in rising interest rates and has other adverse effects on the market, it may adversely affect our consolidated financial condition and results of operations.

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Business disruptions could seriously harm our future revenue and financial condition and increase our costs and expenses.

Our operations, and those of our third-party research institution and pharmaceutical company collaborators, manufacturers, and other contractors and consultants, could be subject to earthquakes, power shortages, telecommunications failures, water shortages, floods, hurricanes, typhoons, fires, extreme weather conditions, medical or public health crises, such as the COVID-19 pandemic, and other natural or man-made disasters or business interruptions, including terrorism and war. In addition, for some of our clinical trials, we rely on third-party research institution collaborators for conducting research and development of our product candidates, and they may be affected by government shutdowns or withdrawn funding. The occurrence of any of these business disruptions could seriously harm our operations and financial condition and increase our costs and expenses. We rely on third-party manufacturers to produce and process our product candidates. Our ability to obtain clinical supplies of our product candidates could be disrupted if the operations of these suppliers are affected by a man-made or natural disaster or other business interruption.

The majority of our operations, including our corporate headquarters, are located in the San Francisco Bay Area of California. Damage or extended periods of interruption to our corporate, development or research facilities due to fire, natural disaster, power loss, communications failure, unauthorized entry or other events could cause us to cease or delay development of some or all of our product candidates. Although we maintain customary insurance coverage, our insurance might not cover all losses under such circumstances and our business may be seriously harmed by such delays and interruption.

In February 2022, Russia commenced a war against Ukraine. The sanctions announced by the U.S. and other countries against Russia as a result include restrictions on selling or importing goods, services, or technology in or from affected regions and travel bans and asset freezes impacting connected individuals and political, military, business, and financial organizations in Russia. The United States and other countries could impose wider sanctions and take other actions should the conflict further escalate. It is not possible to predict the broader consequences of this conflict, which could include further sanctions, embargoes, regional instability, threats of cyberattacks, prolonged periods of higher inflation, geopolitical shifts, and adverse effects on macroeconomic conditions, currency exchange rates, and financial markets, all of which could have a material adverse effect on our business, financial condition, and results of operations.

We are subject to governmental export and import controls that could impair our ability to compete in international markets or subject us to liability if we violate these controls.

Our products may be subject to U.S. export control laws and regulations including the Export Administration Regulations (“EAR”) and trade and economic sanctions maintained by the Office of Foreign Assets Control (“OFAC”). As such, an export license may be required to export, reexport, or transfer our products to certain countries, end-users, and end-uses. If we were to fail to comply with such U.S. export controls laws and regulations, U.S. economic sanctions, or other similar laws, we could be subject to both civil and criminal penalties, including substantial fines, possible incarceration for employees and managers for willful violations, and the possible loss of our export or import privileges. Obtaining the necessary export license for a particular sale or offering may not be possible and may be time-consuming and may result in the delay or loss of sales opportunities. Furthermore, U.S. export control laws and economic sanctions prohibit the export of products to certain U.S. embargoed or sanctioned countries, governments, and persons, as well as for prohibited end-uses. Even though we take precautions to ensure that we and our partners comply with all relevant export control laws and regulations, any failure by us or our partners, including third party manufacturers, to comply with such laws and regulations could have negative consequences for us, including reputational harm, government investigations and penalties.

Changes in our products or changes in export and import regulations in such countries may create delays in the introduction of our products into international markets, prevent our end-customers with international operations from deploying our products globally or, in some cases, prevent or delay the export or import of our products to certain countries, governments or persons altogether. Any change in export or import laws or regulations,

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economic sanctions or related legislation, shift in the enforcement or scope of existing export, import or sanctions laws or regulations, or change in the countries, governments, persons, or technologies targeted by such export, import or sanctions laws or regulations, could result in decreased use of our products by, or in our decreased ability to export or sell our products to, existing or potential end-customers with international operations. Any decreased use of our products or limitation on our ability to export to or sell our products in international markets could adversely affect our business, financial condition, and results of operations.

Any legal proceedings or claims against us could be costly and time-consuming to defend and could harm our reputation regardless of the outcome.

We may in the future become subject to legal proceedings and claims that arise in the ordinary course of business, including intellectual property, collaboration, licensing agreement, product liability, employment, class action, whistleblower and other litigation claims, and governmental and other regulatory investigations and proceedings. Such matters can be time-consuming, divert management’s attention and resources, cause us to incur significant expenses or liability, or require us to change our business practices. In addition, the expense of litigation and the timing of this expense from period to period are difficult to estimate, subject to change, and could adversely affect our financial condition and results of operations. Because of the potential risks, expenses, and uncertainties of litigation, we may, from time to time, settle disputes, even where we have meritorious claims or defenses, by agreeing to settlement agreements. Any of the foregoing could adversely affect our business, financial condition, and results of operations.

Our ability to use our net operating loss carryforwards and certain other tax attributes may be limited.

As of December 31, 2021, Apexigen had federal net operating loss (“NOL”) carryforwards totaling $129.6 million. Of the $129.6 million, $101.4 million are carried forward indefinitely, but are subject to an 80% of taxable income limitation, and $28.3 million which will begin to expire in 2033, if not utilized. As of December 31, 2021, Apexigen had California NOL carryforwards of $64.5 million, which will begin to expire in 2035, if not utilized. Under Sections 382 and 383 of the United States Internal Revenue Code of 1986, as amended, if a corporation undergoes an “ownership change” (generally defined as a greater than 50-percentage-point cumulative change (by value) in the equity ownership of certain stockholders over a rolling three-year period), the corporation’s ability to use its pre-change NOL carryforwards and other pre-change tax attributes to offset its post-change taxable income or taxes may be limited. As a result of previous financing transactions and/ or in connection with this Business Combination, Apexigen may have experienced, or we may experience, such an ownership change. We may also experience ownership changes in the future as a result of subsequent shifts in our stock ownership, some of which are outside our control. As a result, our ability to use our pre-change NOL carryforwards and other pre-change tax attributes to offset post-change taxable income or taxes may be subject to limitation.

Risks Related to Ownership of Our Common Stock and this Offering

The price of shares of common stock may be volatile or may decline regardless of our operating performance. You may lose some or all of your investment.

The trading price of shares of our common stock is likely to be volatile. The stock market recently has experienced extreme volatility. This volatility often has been unrelated or disproportionate to the operating performance of particular companies. You may not be able to resell your shares at an attractive price due to a number of factors such as those listed in “Risks Related to Apexigen’s Business, Financial Condition, and Need for Additional Capital” and the following:

• the impact of the COVID-19 pandemic on our financial condition and the results of operations;

• our operating and financial performance and prospects;

• our quarterly or annual earnings or those of other companies in our industry compared to market expectations;

• conditions that impact demand for our products and/or services;

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• future announcements concerning our business, our clients’ businesses or our competitors’ businesses;

• the public’s reaction to our press releases, other public announcements and filings with the SEC;

• the market’s reaction to our reduced disclosure and other requirements as a result of being an “emerging growth company” under the Jumpstart Our Business Startups Act (the “JOBS Act”);

• the size of our public float;

• coverage by or changes in financial estimates by securities analysts or failure to meet their expectations;

• market and industry perception of our success, or lack thereof, in pursuing our growth strategy;

• strategic actions by us or our competitors, such as acquisitions or restructurings;

• changes in laws or regulations which adversely affect our industry or us;

• privacy and data protection laws, privacy or data breaches, or the loss of data;

• changes in accounting standards, policies, guidance, interpretations or principles;

• changes in senior management or key personnel;

• issuances, exchanges or sales, or expected issuances, exchanges or sales of our capital stock;

• changes in our dividend policy;

• adverse resolution of new or pending litigation against us; and

• changes in general market, economic and political conditions in the United States and global economies or financial markets, including those resulting from natural disasters, terrorist attacks, acts of war and responses to such events.

These broad market and industry factors may materially reduce the market price of shares of Company common stock, regardless of our operating performance. In addition, price volatility may be greater if the public float and trading volume of Company common stock is low. As a result, you may suffer a loss on your investment.

In the past, following periods of market volatility, stockholders have instituted securities class action litigation. If we were involved in securities litigation, it could have a substantial cost and divert resources and the attention of executive management from our business regardless of the outcome of such litigation.

If the Business Combination’s benefits do not meet the expectations of financial analysts, the market price of our common stock may decline.

The market price of our common stock may decline as a result of the Business Combination if we do not achieve the perceived benefits of the Business Combination as rapidly, or to the extent anticipated by, financial analysts or the effect of the Business Combination on our financial results is not consistent with the expectations of financial analysts. Accordingly, holders of our common stock may experience a loss as a result of a decline in the market price of such common stock. In addition, a decline in the market price of our common stock following the consummation of the Business Combination could adversely affect our ability to issue additional securities and to obtain additional financing in the future.

The warrants may never be in the money and may expire worthless.

The exercise price of the warrants is $11.50 per share. We believe the likelihood that warrant holders will exercise the warrants, and therefore the amount of cash proceeds that we would receive, is dependent upon the trading price of our common stock, the last reported sales price for which was $4.37 per share on August 30, 2022. If the trading price for our common stock is less than the $11.50 exercise price per share of the warrants, we expect that warrant holders will not exercise their warrants. There is no guarantee that the warrants will be in the money following the time they become exercisable and prior to their expiration, and as such, the warrants may expire worthless and we may receive no proceeds from the exercise of the warrants.

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There can be no assurance that we will be able to comply with the continued listing standards of Nasdaq.

If Nasdaq delists our shares from trading on its exchange for failure to meet the listing standards, we and our stockholders could face significant material adverse consequences including:

• a limited availability of market quotations for our securities;

• reduced liquidity for our securities;

• a determination that our common stock is a “penny stock” which will require brokers trading in our common stock to adhere to more stringent rules, possibly resulting in a reduced level of trading activity in the secondary trading market for shares of our common stock;

• a limited amount of analyst coverage; and

• a decreased ability to issue additional securities or obtain additional financing in the future.

Certain of our warrants are accounted for as a warrant liability and are recorded at fair value upon issuance with changes in fair value each period reported in earnings, which may have an adverse effect on the market price of our common stock.

As of the Closing Date, we had 123,500 private placement warrants outstanding. These warrants will become exercisable 30 days after the Closing Date provided that we have an effective registration statement under the Securities Act covering the shares of our common stock issuable upon exercise and a current prospectus relating to them is available and such shares are registered, qualified or exempt from registration under the securities, or blue sky, laws of the state of residence of the holder (or we permit holders to exercise their warrants on a cashless basis under certain circumstances). Once the private placement warrants become exercisable, we may redeem outstanding warrants in certain circumstances. Under GAAP, we are required to evaluate contingent exercise provisions of these warrants and then their settlement provisions to determine whether they should be accounted for as a warrant liability or as equity. Any settlement amount not equal to the difference between the fair value of a fixed number of our equity shares and a fixed monetary amount precludes these warrants from being considered indexed to its own stock, and therefore, from being accounted for as equity. As a result of the provision that the private placement warrants, when held by someone other than the initial purchasers or their permitted transferees, will be redeemable by us, the requirements for accounting for these warrants as equity are not satisfied. Therefore, we are required to account for these private placement warrants as a warrant liability and record (a) that liability at fair value, and (b) any subsequent changes in fair value as of the end of each period for which earnings are reported. The impact of changes in fair value on earnings may have an adverse effect on the market price of our common stock.

We have identified a material weakness in our internal control over financial reporting as of June 30, 2021. If we are unable to maintain an effective system of internal control over financial reporting, we may not be able to accurately report our financial results in a timely manner, which may adversely affect investor confidence in us and materially and adversely affect our business and operating results.

In connection with the reclassification of our warrants, we identified a material weakness in our internal controls over financial reporting.

A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting such that there is a reasonable possibility that a material misstatement of our annual or interim financial statements will not be prevented or detected and corrected on a timely basis.

Effective internal controls are necessary for us to provide reliable financial reports and prevent fraud.

If we identify any material weaknesses in our internal control over financial reporting, any such identified material weakness could limit our ability to prevent or detect a misstatement of our accounts or disclosures that could result in a material misstatement of our annual or interim financial statements. In such case, we may be

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unable to maintain compliance with securities law requirements regarding timely filing of periodic reports in addition to applicable stock exchange listing requirements, investors may lose confidence in our financial reporting and our stock price may decline as a result. We cannot assure you that the measures we have taken to date, or any measures we may take in the future, will be sufficient to avoid potential future material weaknesses.

We do not intend to pay dividends on shares of our common stock for the foreseeable future.

We currently intend to retain all available funds and any future earnings to fund the development and growth of our business. As a result, we do not anticipate declaring or paying any cash dividends on shares of Company common stock in the foreseeable future. Any decision to declare and pay dividends in the future will be made at the discretion of our Board and will depend on, among other things, our business prospects, results of operations, financial condition, cash requirements and availability, certain restrictions related to our indebtedness, industry trends and other factors that our Board may deem relevant. Any such decision will also be subject to compliance with contractual restrictions and covenants in the agreements governing our current and future indebtedness. In addition, we may incur additional indebtedness, the terms of which may further restrict or prevent us from paying dividends on our common stock. As a result, you may have to sell some or all of your shares of our common stock after price appreciation in order to generate cash flow from your investment, which you may not be able to do. Our inability or decision not to pay dividends, particularly when others in our industry have elected to do so, could also adversely affect the market price of shares of our common stock.

If securities analysts do not publish research or reports about us, or if they issue unfavorable commentary about us or our industry or downgrade our common stock, the price of shares of our common stock could decline.

The trading market for shares of our common stock will depend in part on the research and reports that third-party securities analysts publish about us and the industries in which we operate. We may be unable or slow to attract research coverage and if one or more analysts cease coverage of us, the price and trading volume of our securities would likely be negatively impacted. If any of the analysts that may cover us change their recommendation regarding our securities adversely, or provide more favorable relative recommendations about our competitors, the price of our securities would likely decline. If any analyst that may cover us ceases covering us or fails to regularly publish reports on us, we could lose visibility in the financial markets, which could cause the price or trading volume of our securities to decline. Moreover, if one or more of the analysts who cover us downgrades our common stock, or if our reporting results do not meet their expectations, the market price of shares of our common stock could decline.

Our issuance of additional shares of common stock could make it difficult for another company to acquire us, may dilute your ownership of us and could adversely affect our stock price.

We intend to file a registration statement with the SEC on Form S-8 providing for the registration of shares of our common stock issued or reserved for issuance under our 2020 Plan, 2022 Plan and 2022 ESPP. Subject to the satisfaction of vesting conditions and the expiration of any applicable lockup agreements, shares registered under the registration statement on Form S-8 will be available for resale immediately in the public market without restriction. In addition, under the purchase agreement dated March 17, 2022 that we entered into with Lincoln Park (the “Lincoln Park Purchase Agreement”), we will have the right to direct Lincoln Park to purchase an aggregate of up to $50,000,000 of our common stock from time to time, subject to certain limitations contained in the Lincoln Park Purchase Agreement. Pursuant to the Lincoln Park Purchase Agreement, we issued to Lincoln Park 150,000 shares of our common stock on the Closing Date, and we will issue to Lincoln Park $1,500,000 of additional shares of common stock on the date that is 90 calendar days after the Closing Date, subject to a maximum number of 500,000 shares.

From time to time in the future, we may also issue additional shares of common stock or securities convertible into common stock pursuant to a variety of transactions, including acquisitions. The issuance by us of additional shares of common stock or securities convertible into common stock would dilute your ownership of us and the sale of a significant amount of such shares in the public market could adversely affect prevailing market prices of shares of our common stock.

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In the future, we expect to obtain financing or to further increase our capital resources by issuing additional shares of our capital stock or offering debt or other equity securities, including senior or subordinated notes, debt securities convertible into equity, or shares of preferred stock. Issuing additional shares of our capital stock, other equity securities, or securities convertible into equity may dilute the economic and voting rights of our existing stockholders, reduce the market price of shares of our common stock, or both. Debt securities convertible into equity could be subject to adjustments in the conversion ratio pursuant to which certain events may increase the number of equity securities issuable upon conversion. Preferred stock, if issued, could have a preference with respect to liquidating distributions or a preference with respect to dividend payments that could limit our ability to pay dividends to the holders of our common stock. Our decision to issue securities in any future offering will depend on market conditions and other factors beyond our control, which may adversely affect the amount, timing or nature of our future offerings. As a result, holders of our common stock bear the risk that our future offerings may reduce the market price of shares of our common stock and dilute their percentage ownership. See “Description of Securities.”

Sales of our common stock, or the perception of such sales, by us or our existing stockholders in the public market could cause the market price for our common stock to decline and certain Selling Securityholders still may receive significant proceeds.

The sale of substantial amounts of shares of our common stock in the public market, or the perception that such sales could occur, could harm the prevailing market price of shares of our common stock. These sales, or the possibility that these sales may occur, also might make it more difficult for us to sell equity securities in the future at a time and at a price that we deem appropriate. Resales of our common stock may cause the trading price of our securities to drop significantly.

Subject to the expiration of any applicable lock-up agreements, all shares issued as merger consideration in the Business Combination are freely tradable without registration under the Securities Act and without restriction by persons other than our “affiliates” (as defined under Rule 144), including our directors, executive officers and other affiliates, and certain other former Apexigen stockholders.

Shares held by certain of our stockholders will be eligible for resale, subject to, in the case of certain stockholders, volume, manner of sale and other limitations under Rule 144. In addition, pursuant to the Registration Rights and Lock-Up Agreement that we entered into with certain stockholders in connection with the Business Combination, certain of our stockholders have the right, subject to certain conditions, to require us to register the sale of their shares of common stock under the Securities Act, and pursuant to the Registration Rights Agreement that we entered into with Lincoln Park, we have an obligation to register the shares of our common stock issued to Lincoln Park pursuant to the Lincoln Park Purchase Agreement under the Securities Act. By exercising their registration rights and selling a large number of shares, these stockholders could cause the prevailing market price of shares of our common stock to decline.

As restrictions on resale end or if these stockholders exercise their registration rights, the market price of shares of our common stock could drop significantly if the holders of these shares sell them or are perceived by the market as intending to sell them. These factors could also make it more difficult for us to raise additional funds through future offerings of shares of our common stock or other securities.

This prospectus also registers the shares of common stock being offered for resale pursuant to this prospectus by the Selling Securityholders, which represent approximately 67.3% of shares outstanding as of the Closing Date. Certain of these shares of common stock were purchased at prices that were significantly below the current trading price of our common stock and the sale of such shares could result in the Selling Securityholder realizing a significant gain. Our predecessor’s sponsor, Brookline Capital Holdings, LLC, our predecessor’s IPO underwriter and certain of its employees (the “Sponsor and Representatives”) paid an aggregate of $2.5 million, or a weighted average price per share of approximately $1.99 for the 1,248,479 Private Shares they currently hold. Certain former stockholders of Legacy Apexigen, including our officers and directors paid an aggregate of

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$83.3 million, or a weighted average price per share of approximately $10.40, for the 8,009,884 Business Combination Shares they currently hold.

Even though our trading price is significantly below the price of our common stock at the time of the closing of the Business Combination, certain of the Selling Securityholders, including the Sponsor and Representatives and certain Legacy Apexigen stockholders, may still have incentive to sell shares of common stock because they purchased the shares at prices lower than the current trading price of our common stock and may profit substantially even under circumstances in which our public stockholders may experience losses in connection with their investment. For example, based on the closing price of our common stock of $4.37 on August 30, 2022, the Sponsor and Representatives would experience a potential profit of up to approximately $4.35 per share, or up to approximately $4.4 million in the aggregate, if they sold their shares at that price, and certain former stockholders of Legacy Apexigen, including our officers and directors would experience a potential profit of up to approximately $4.37 per share, or up to approximately $28.1 million in the aggregate. Public stockholders that purchased shares of common stock of our predecessor prior to the Business Combination may have paid more than the Sponsor and Representatives, other holders of the Private Shares, or holders of our Business Combination Shares for their shares and would not expect to see a positive return unless our stock price appreciates above the price at which such stockholders purchased their shares.

In addition, the shares of Company common stock reserved for future issuance under the 2022 Plan and 2022 ESPP will become eligible for sale in the public market once those shares are issued, subject to provisions relating to various vesting agreements, lock-up agreements and, in some cases, limitations on volume and manner of sale applicable to affiliates under Rule 144, as applicable. As of the Closing Date, the number of shares reserved for future issuance under (i) the 2022 Plan is 2,573,405 shares, and (ii) the 2022 ESPP is 257,341 shares. We expect to file one or more registration statements on Form S-8 under the Securities Act to register shares of our common stock or securities convertible into or exchangeable for shares of our common stock issued pursuant to our equity incentive plans. Any such Form S-8 registration statements will automatically become effective upon filing. Accordingly, shares registered under such registration statements will be available for sale in the open market.

Our management team has limited experience in operating a public company.

Our executive officers have limited experience in the management of a publicly traded company. Our management team may not successfully or effectively manage its transition to a public company that will be subject to significant regulatory oversight and reporting obligations under federal securities laws. For example, we failed to timely file our Form 10-Q for the quarter ended June 30, 2022. Their limited experience in dealing with the increasingly complex laws pertaining to public companies could be a significant disadvantage in that it is likely that an increasing amount of their time may be devoted to these activities which will result in less time being devoted to the management and growth of the company. We may not have adequate personnel with the appropriate level of knowledge, experience, and training in the accounting policies, practices or internal controls over financial reporting required of public companies in the United States. The development and implementation of the standards and controls necessary for us to achieve the level of accounting standards required of a public company in the United States may require costs greater than expected. It is possible that we will be required to expand our employee base and hire additional employees to support our operations as a public company which will increase our operating costs in future periods.

As a public reporting company, we are subject to rules and regulations established from time to time by the SEC regarding our internal control over financial reporting.

We are a public reporting company subject to the rules and regulations established from time to time by the SEC and Nasdaq. These rules and regulations require, among other things that we establish and periodically evaluate procedures with respect to our internal control over financial reporting. Reporting obligations as a public company are likely to place a considerable strain on our financial and management systems, processes and controls, as well as on our personnel.

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In addition, as a public company, we are required to document and test our internal control over financial reporting pursuant to Section 404 of the Sarbanes-Oxley Act so that our management can certify as to the effectiveness of our internal control over financial reporting. If we are not able to implement the requirements of Section 404, including any additional requirements once we are no longer an emerging growth company, in a timely manner or with adequate compliance, we may not be able to assess whether our internal control over financial reporting are effective, which may subject us to adverse regulatory consequences and could harm investor confidence and the market price of our common stock.

Additionally, once we are no longer an emerging growth company, we will be required to comply with the independent registered public accounting firm attestation requirement on our internal control over financial reporting. We will be an “emerging growth company” until the earlier of (1) the last day of the fiscal year (a) following February 2, 2026, the fifth anniversary of the BCAC IPO, (b) in which we have total annual gross revenue of at least $1.07 billion or (c) in which we are deemed to be a large accelerated filer, which means the market value of our common stock that is held by non-affiliates exceeds $700 million as of the last business day of our prior second fiscal quarter, and (2) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period. Until we cease being an emerging growth company stockholders will not have the benefit of an independent assessment of the effectiveness of our internal control environment.

As an “emerging growth company,” we cannot be certain if the reduced disclosure requirements applicable to “emerging growth companies” will make our common stock less attractive to investors.

As an “emerging growth company,” we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not “emerging growth companies,” including not being required to obtain an assessment of the effectiveness of our internal controls over financial reporting from our independent registered public accounting firm pursuant to Section 404 of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, and exemptions from the requirements of holding a non-binding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved. 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, which we have elected to do.

We cannot predict if investors will find our common stock less attractive because we will rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active market for our common stock, our share price may be more volatile and the price at which our securities trade could be less than if we did not use these exemptions.

Anti-takeover provisions in our governing documents and under Delaware law could make an acquisition of us more difficult, limit attempts by our stockholders to replace or remove our current management and limit the market price of our common stock.

Our amended and restated certificate of incorporation and bylaws and Delaware law contain provisions that could have the effect of rendering more difficult, delaying, or preventing an acquisition deemed undesirable by our Board. Among other things, our amended and restated certificate of incorporation and/or bylaws include the following provisions:

• a staggered board, which means that our Board is classified into three classes of directors with staggered three-year terms and directors are only able to be removed from office for cause;

• limitations on convening special stockholder meetings, which could make it difficult for our stockholders to adopt desired governance changes;

• a prohibition on stockholder action by written consent, which means that our stockholders are only be able to take action at a meeting of stockholders and are not able to take action by written consent for any matter;

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• a forum selection clause, which means certain litigation against us can only be brought in Delaware;

• the authorization of undesignated preferred stock, the terms of which may be established and shares of which may be issued without further action by our stockholders; and

• advance notice procedures, which apply for stockholders to nominate candidates for election as directors or to bring matters before an annual meeting of stockholders.

These provisions, alone or together, could delay or prevent hostile takeovers and changes in control or changes in our management. As a Delaware corporation, we are also subject to provisions of Delaware law, including Section 203 of the DGCL, which prevents interested stockholders, such as certain stockholders holding more than 15% of our outstanding common stock, from engaging in certain business combinations unless (i) prior to the time such stockholder became an interested stockholder, the Board approved the transaction that resulted in such stockholder becoming an interested stockholder, (ii) upon consummation of the transaction that resulted in such stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the common stock, or (iii) following Board approval, such business combination receives the approval of the holders of at least two-thirds of our outstanding common stock not held by such interested stockholder.

Any provision of our amended and restated certificate of incorporation and/or bylaws or Delaware law that has the effect of delaying, preventing or deterring a change in control could limit the opportunity for our stockholders to receive a premium for their shares of our common stock and could also affect the price that some investors are willing to pay for our common stock.

Our bylaws provide that the Court of Chancery of the State of Delaware is the sole and exclusive forum for substantially all disputes between us and our stockholders, which could limit our stockholders’ ability to obtain a favorable judicial forum for disputes with us or our directors, officers, or employees.

Our amended and restated bylaws provide that, unless we consent in writing to the selection of an alternative forum, the (i) Court of Chancery (the “Chancery Court”) of the State of Delaware (or, in the event that the Chancery Court does not have jurisdiction, the federal district court for the District of Delaware or other state courts of the State of Delaware) shall, to the fullest extent permitted by law, be the sole and exclusive forum for: (A) any derivative action, suit or proceeding brought on our behalf; (B) any action, suit or proceeding asserting a claim of breach of fiduciary duty owed by any of our directors, officers, or stockholders to us or to our stockholders; (C) any action, suit or proceeding asserting a claim arising pursuant to the DGCL, the our amended and restated charter or our amended and restated bylaws; or (D) any action, suit or proceeding asserting a claim governed by the internal affairs doctrine; and (ii) subject to the foregoing, the federal district courts of the United States of America shall be the exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act. Notwithstanding the foregoing, such forum selection provisions shall not apply to suits brought to enforce any liability or duty created by the Exchange Act or any other claim for which the federal courts of the United States have exclusive jurisdiction. The choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees, which may discourage such lawsuits against us and our directors, officers, and other employees. Alternatively, if a court were to find the choice of forum provision contained in the Company’s bylaws to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could harm our business, results of operations, and financial condition.

Additionally, Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all suits brought to enforce any duty or liability created by the Securities Act or the rules and regulations thereunder. As noted above, our amended and restated bylaws provide that the federal district courts of the United States of America shall have jurisdiction over any action arising under the Securities Act. Accordingly, there is uncertainty as to whether a court would enforce such provision. Our stockholders will not be deemed to have waived our compliance with the federal securities laws and the rules and regulations thereunder.

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MARKET, INDUSTRY AND OTHER DATA

Unless otherwise indicated, information contained in this prospectus concerning our industry and the market in which we operate, including our general expectations and market position, market opportunity, and market size, is based on information from various third-party industry and research sources, on assumptions that we have made based on that data and other similar sources, and on our knowledge of the markets for our services. This information involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates.

In addition, industry publications, studies, and surveys generally state that they have been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described in the section captioned “Risk Factors” and elsewhere in this prospectus. These and other factors could cause our actual results to differ materially from those expressed in the estimates made by the independent parties and by us.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements. All statements other than statements of historical facts contained in this prospectus, including statements regarding our future results of operations and financial position, business strategy, product candidates, planned preclinical studies and clinical trials, results of clinical trials, research and development costs, regulatory approvals, timing and likelihood of success, as well as plans and objectives of management for future operations, are forward-looking statements. These statements involve known and unknown risks, uncertainties, and other important factors that are in some cases beyond our control and may cause our actual results, performance, or achievements to be materially different from any future results, performance, or achievements expressed or implied by the forward-looking statements.

In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “would,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “believe,” “estimate,” “predict,” “potential,” “seek,” “aim,” or “continue” or the negative of these terms or other similar expressions. Forward-looking statements contained in this prospectus include, but are not limited to, statements about:

• our success in retaining or recruiting, or changes required in, our officers, key employees or directors following the Business Combination;

• our public securities’ potential liquidity and trading;

• the lack of a market for our securities;

• our financial performance following this offering;

• failure to realize the anticipated benefits of the Business Combination;

• the outcome of any legal proceedings that may be instituted against us related to the Business Combination;

• the timing and focus of Apexigen’s current and future clinical trials, and the reporting of data from those trials;

• Apexigen’s ability to obtain and maintain regulatory approval of its product candidates;

• Apexigen’s estimates of the number of patients in the United States who suffer from the diseases it is targeting and the number of patients that will enroll in clinical trials;

• the timing or likelihood of regulatory filings and approvals for Apexigen’s product candidates for various diseases;

• Apexigen’s plans relating to commercializing its product candidates, if approved, including which indications will be pursued;

• the ability of Apexigen’s clinical trials to demonstrate safety and efficacy, and other positive results, of its product candidates;

• the beneficial characteristics, safety, efficacy, and therapeutic effects of Apexigen’s product candidates;

• the development of competitors’ product candidates;

• existing regulations and regulatory developments in the United States and other jurisdictions;

• the need to hire additional personnel and our ability to attract and retain such personnel;

• Apexigen’s plans and ability to obtain, maintain, enforce, or protect intellectual property rights;

• Apexigen’s continued reliance on third parties to conduct additional clinical trials of its product candidates, and for the manufacture of its product candidates for preclinical studies and clinical trials; and

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• the success of Apexigen’s licensing agreements.

We have based these forward-looking statements largely on our current expectations and projections about our business, the industry in which we operate and financial trends that we believe may affect our business, financial condition, results of operations, and prospects, and these forward-looking statements are not guarantees of future performance or development. These forward-looking statements speak only as of the date of this prospectus and are subject to a number of risks, uncertainties, and assumptions described in the section titled “Risk Factors” and elsewhere in this prospectus. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified, you should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein until after we distribute this prospectus, whether as a result of any new information, future events, or otherwise.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.

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UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

Capitalized terms used but not defined in this Exhibit 99.3 shall have the meanings ascribed to them in the Current Report on Form 8-K (the “Form 8-K”) filed with the Securities and Exchange Commission (the “SEC”) on August 4, 2022, as amended, and, if not defined in the Form 8-K, the definitive proxy statement/prospectus/information statement filed by BCAC with the Securities and Exchange Commission (the “SEC”) on June 30, 2022 (the “Proxy Statement”).

Unless the context otherwise requires, all references to (i) the “Combined Company” refer to the entity formerly known as Brookline Capital Acquisition Corp., which is now named Apexigen, Inc. after giving effect to the Business Combination; (ii) “Legacy Apexigen” refer to the entity formerly known as Apexigen, Inc., which is now named Apexigen America, Inc. after giving effect to the Business Combination; and (iii) “BCAC” refer to Brookline Capital Acquisition Corp. prior to giving effect to Combination.

The Combined Company is providing the following unaudited pro forma condensed combined financial information to aid in the analysis of the financial aspects of the Merger and other events contemplated by the Business Combination Agreement. The following unaudited pro forma condensed combined financial information presents the combination of the financial information of BCAC and Legacy Apexigen, adjusted to give effect to the Merger and other events contemplated by the Business Combination Agreement. The following unaudited pro forma condensed combined financial information has been prepared in accordance with Article 11 of Regulation S-X as amended by the final rule, Release 33-10786 “Amendments to Financial Disclosures about Acquired and Disposed Businesses” (“Article 11 of Regulation S-X”).

The unaudited pro forma condensed combined financial statements give effect to the Merger and other events contemplated by the Business Combination Agreement as described in this prospectus. The unaudited pro forma condensed combined balance sheet as of June 30, 2022 combines the historical unaudited condensed balance sheet of Legacy Apexigen with the historical unaudited condensed balance sheet of BCAC on a pro forma basis as if the Merger and the other events contemplated by the Business Combination Agreement, summarized below, had been consummated on June 30, 2022. The unaudited pro forma condensed combined statement of operations for the six months ended June 30, 2022 combines the historical unaudited condensed statement of operations of Legacy Apexigen for the six months ended June 30, 2022 and the historical unaudited condensed statement of operations of BCAC for the six months ended June 30, 2022, giving effect to the transaction as if the Merger and other events contemplated by the Business Combination Agreement had been consummated on January 1, 2021. The unaudited pro forma condensed combined statement of operations for the year ended December 31, 2021 combines the historical audited statement of operations of BCAC for the year ended December 31, 2021, with the historical audited statement of operations of Legacy Apexigen for the year ended December 31, 2021, giving effect to the transaction as if the Merger and other events contemplated by the Business Combination Agreement had been consummated on January 1, 2021.

The unaudited pro forma condensed combined financial statements have been prepared for informational purposes only and are not necessarily indicative of what the Combined Company’s condensed financial position or results of operations actually would have been had the Business Combination been consummated prior to June 30, 2022, nor are they necessarily indicative of future results of operations. In addition, the unaudited pro forma condensed combined financial statements do not purport to project the future financial position or operating results of the Combined Company.

The unaudited pro forma condensed combined financial information was derived from and should be read in conjunction with the following historical financial statements and the accompanying notes:

• audited historical financial statements of BCAC for the year ended December 31, 2021 filed with this prospectus;

• unaudited historical condensed financial statements of BCAC as of and for the six months ended June 30, 2022 filed with this prospectus;

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• audited historical financial statements of Legacy Apexigen for the year ended December 31, 2021 filed with this prospectus;

• unaudited historical condensed financial statements of Legacy Apexigen as of and for the six months ended June 30, 2022 filed with this prospectus; and

• other information relating to BCAC and Apexigen included in this prospectus, including the Business Combination Agreement and the description of certain terms thereof and the financial and operational condition of BCAC and Apexigen.

Description of the Merger

Pursuant to the Business Combination Agreement, Merger Sub merged with and into Legacy Apexigen, with Legacy Apexigen surviving the Merger and thereby becoming a wholly owned subsidiary of BCAC. In connection with the Merger, Legacy Apexigen was renamed “Apexigen America, Inc.” and BCAC was renamed as “Apexigen, Inc.” (hereafter referred to as Apexigen). The Merger consideration paid to the Legacy Apexigen equity holders at the Closing pursuant to the Business Combination Agreement has deemed to have a value of $205 million, assuming a deemed value of $10.00 per BCAC common share. Upon the consummation of the Merger, each share of Legacy Apexigen capital stock was converted into the right to receive shares of Combined Company common stock. Each share of Legacy Apexigen capital stock received a deemed value of $9.76 per share, assuming a deemed value of $10.00 per BCAC common share, after giving effect to the exchange ratio of 0.102448 (the “Exchange Ratio”).

Following the Merger and related events, 18,151,571 shares of Combined Company common stock were issued to Legacy Apexigen’s equity holders and are outstanding, 1,452,000 shares of Combined Company common stock and 726,000 Public Warrants were issued and are outstanding related to the PIPE Units, 2,875,000 Public Warrants remain issued and outstanding, 123,500 Private Warrants remain issued and outstanding, 150,000 shares of Combined Company common stock were issued to Lincoln Park as consideration under the Lincoln Park Purchase Agreement and are outstanding, Combined Company Warrants related to the exchange of a Legacy Apexigen Warrant and exercisable for 4,321 shares of Combined Company common stock is outstanding, and Combined Company Options related to the exchange of Legacy Apexigen Options and exercisable for 3,415,868 of Combined Company common stock are outstanding. Following the Merger and related events, 442,985 shares of Combined Company common stock held by BCAC stockholders prior to the Closing remain issued and outstanding. Following the Merger and related events, 1,190,979 shares of Combined Company held by the Sponsor, comprised of Founder Shares and BCAC Common Stock issued in the Private Placement, remain issued and outstanding. Following the Merger and related events, 57,500 shares of Combined Company common stock held by the BCAC IPO Underwriter and Certain of Its Employees remain issued and outstanding.

The following transactions constituting the Merger took place as contemplated by the Business Combination Agreement:

• the Merger of Merger Sub, the wholly owned subsidiary of BCAC, with and into Legacy Apexigen, with Legacy Apexigen as the surviving company;

• the cancellation of each issued and outstanding share of Legacy Apexigen’s capital stock (including shares of Apexigen capital stock resulting from the conversion of Legacy Apexigen’s preferred stock or the exercise of Legacy Apexigen Options or Legacy Apexigen Warrants) and the conversion into the right to receive a number of shares of Combined Company common stock based on the Exchange Ratio;

• the conversion on a net-exercise basis of one Legacy Apexigen Warrant (the “Convertible Warrant”), pursuant to its terms, immediately prior to the Closing into shares of Combined Company common stock based on the Exchange Ratio;

• the exchange of an outstanding Legacy Apexigen Warrant (other than the Convertible Warrant) into a warrant exercisable for shares of Combined Company common stock with the same terms except for the number of shares exercisable and the exercise price, each of which was adjusted using the Exchange Ratio; and

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• the exchange of all outstanding vested and unvested Legacy Apexigen Options into Combined Company Options exercisable for shares of Combined Company common stock with the same terms. except for the number of shares exercisable and the exercise price, each of which was adjusted using the Exchange Ratio.

Other Related Events in Connection with the Merger

Other related events that are contemplated to take place in connection with the Merger are summarized below:

• PIPE Investment: Issuance and sale of 1,452,000 PIPE Units at a purchase price of $10.00 per unit pursuant to the PIPE Investment. The PIPE Investors purchased units, each of which includes one share of Combined Company common stock and one-half of one warrant to purchase a share of Combined Company common stock. The PIPE Investment resulted in the issuance of 1,452,000 shares of Combined Company common stock and 726,000 PIPE Warrants. In addition, shortly after the Closing Apexigen anticipates issuing and selling 50,000 additional PIPE Units for proceeds of $500,000. These additional PIPE Units have not been reflected in the pro forma.

• Lincoln Park Purchase Arrangement: BCAC, Legacy Apexigen and Lincoln Park entered into a purchase agreement pursuant to which the Combined Company may direct Lincoln Park to purchase up to $50.0 million of Combined Company common stock from time to time over a 24-month period following the Closing, subject to certain limitations contained in the Lincoln Park Purchase Agreement. At the Closing, the Combined Company issued 150,000 shares of Combined Company common stock to Lincoln Park. 90 days after the Closing, the Combined Company is obligated to issue $1.5 million of shares of Combined Company common stock to Lincoln Park at a price per share equal to the arithmetic average of the closing sale price for Combined Company common stock during the 10 consecutive business days immediately preceding the share delivery date, not to exceed 500,000 shares.

• Forfeited Sponsor Shares: In connection with the Closing, the Sponsor forfeited 436,021 shares of common stock.

• BCAC Stockholder Redemptions: On April 26, 2022, BCAC held a special meeting of its stockholders. BCAC stockholders approved a proposal to amend BCAC’s Amended and Restated Certificate of Incorporation to extend the date by which BCAC must consummate a business combination transaction from May 2, 2022 on a monthly basis up to November 2, 2022. In connection with this special meeting, BCAC Public Stockholders elected to redeem 688,408 shares of common stock for total redemption proceeds of $7.0 million (the “April Partial Redemption”). The April Partial Redemption is reflected in the unaudited historical condensed financial statements of BCAC as of June 30, 2022. In addition, BCAC Public Stockholders elected to redeem 4,618,607 additional shares of Combined Company common stock for $47.2 million upon the Merger Closing (the “Closing Redemption”). These redemptions have been reflected below.

• Sponsor Extension Note: In May and June 2022, BCAC issued non-convertible unsecured promissory notes in the principal amount of $0.5 million to the Sponsor (“Extension Notes”) in exchange for funds that were deposited into the Trust Account. The Extension Notes were issued in connection with the approval of the Amendment to BCAC’s Amended and Restated Certificate of Incorporation and extension (the “Extension”) of the date by which the Company was required to consummate a business combination transaction from May 2, 2022 (the date which was 15 months from the closing date of the Company’s initial public offering of units) and constitute monthly contributions. The Sponsor was repaid in cash upon the Merger Closing. These transactions have been reflected below.

• Sponsor Working Capital Note: On May 2, 2022, BCAC issued an additional convertible unsecured promissory note (the “Working Capital Note”) in the principal amount of $0.4 million to the Sponsor. The Working Capital Note was issued to provide BCAC with additional working capital during the Extension and will not be deposited into the Trust Account. BCAC issued the Working Capital Note in consideration for a loan from the Sponsor to fund BCAC’s working capital requirements. As of the Closing Date, approximately $0.4 million was drawn and approximately $65,000 was not drawn of the Working Capital Note principal amount. The Working Capital Note was settled in cash upon the Merger closing.

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Basis of Pro Forma Presentation

The unaudited pro forma condensed combined financial information has been prepared in accordance with Article 11 of Regulation S-X. The adjustments in the unaudited pro forma condensed combined financial information have been identified and presented to provide relevant information necessary for an illustrative understanding of Combined Company upon consummation of the Merger in accordance with GAAP. Assumptions and estimates underlying the unaudited pro forma adjustments set forth in the unaudited pro forma condensed combined financial information are described in the accompanying notes.

The unaudited pro forma condensed combined financial information has been presented for illustrative purposes only and is not necessarily indicative of the operating results and financial position that would have been achieved had the Merger occurred on the dates indicated. Any net cash proceeds remaining after the consummation of the Merger and the other related events contemplated by the Business Combination Agreement are expected to be used for general corporate purposes. The unaudited pro forma condensed combined financial information does not purport to project the future operating results or financial position of Combined Company following the completion of the Merger. The unaudited pro forma adjustments represent management’s estimates based on information available as of the date of these unaudited pro forma condensed combined financial information and are subject to change as additional information becomes available and analyses are performed. BCAC and Legacy Apexigen did not have any historical relationship prior to the discussion of the Merger. Accordingly, no pro forma adjustments were required to eliminate activities between the companies.

Pursuant to its certificate of incorporation and as contemplated by the Business Combination Agreement, BCAC provided the holders of BCAC Common Stock the opportunity to redeem the outstanding shares of BCAC Common Stock for cash equal to their pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the transactions (including interest earned on the funds held in the Trust Account, net of taxes). The per share redemption amount was approximately $10.10 in the April Partial Redemption and was approximately $10.22 in the Closing Redemption.

The following table presents the selected pro forma information after giving effect to the Merger and other events contemplated by the Business Combination Agreement and the April Partial redemption. This scenario includes the April Partial Redemption and the Closing Redemption, following which 442,985 shares of BCAC Common Stock remain outstanding after the completion of the Merger. The following summarizes the pro forma shares of the Combined Company common stock issued and outstanding immediately after the Merger:

	Shares		%
BCAC Public Stockholders (1)		442,985		2.1	%
Sponsor (2)		1,190,979		5.6	%
BCAC IPO Underwriter and Certain of Its Employees (3)		57,500		0.2	%
Legacy Apexigen equity holders (4)		18,151,571		84.6	%
PIPE Investors (5)		1,452,000		6.8	%
Lincoln Park (6)		150,000		0.7	%
Combined Company common stock outstanding at Merger Closing		21,445,035		100.0	%

(1) Amount reflects the April Partial Redemption and the Closing Redemption. Amount excludes 2,875,000 outstanding Public Warrants issued in connection with the BCAC IPO as such securities are not exercisable until August 28, 2022, the date that is 30 days after the Merger Closing.

(2) The Sponsor holds 1,190,979 shares of BCAC Common Stock, comprised of 1,380,000 Founder Shares and 247,000 shares of BCAC Common Stock issued as constituent securities of the units issued in the Private Placement, net of 436,021 shares forfeited by the Sponsor upon the Closing. This amount excludes 123,500 Private Warrants.