UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  x☒                                Filed by a Party other than the Registrant  ¨☐

Check the appropriate box:

OpexaAcer Therapeutics Inc.

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

OPEXA

ACER THERAPEUTICS INC.

2635 TECHNOLOGY FOREST BLVD.ONE GATEWAY CENTER, SUITE 351 (300 WASHINGTON STREET)

THE WOODLANDS, TEXAS 77381NEWTON, MASSACHUSETTS 02458

April 11, 20169, 2018

To Our Shareholders:

You are cordially invited to attend the Annual Meeting of Shareholders of OpexaAcer Therapeutics Inc. on Monday, May 16, 201614, 2018 at 10:00 a.m. CentralPacific Time. The meeting will be held at 2 Houston Center, 909 Fannin,the offices of Pillsbury Winthrop Shaw Pittman LLP, 12255 El Camino Real, Suite 2000, Houston, Texas 77010.300, San Diego, California 92130.

Information about the Annual Meeting, including matters on which shareholders will act, may be found in the Notice of Annual Meeting and Proxy Statement accompanying this letter. We look forward to greeting in person as many of our shareholders as possible.

It is important that your shares be represented and voted at the meeting. Whether or not you plan to attend the Annual Meeting, please complete, sign, date, and promptly return the accompanying proxy in the enclosed envelope or use one of the voting methods described in the attached materials. Returning the proxy does NOT deprive you of your right to attend the Annual Meeting. If you decide to attend the Annual Meeting and wish to change your proxy vote, you may do so automatically by voting in person at the meeting. Please note, however, that if your shares are held of record by a broker, bank or other nominee and you wish to attend and vote in person at the meeting, you must obtain from the record holder a legal proxy issued in your name.

Sincerely yours,

Neil K. Warma,Chris Schelling, President and Chief Executive Officer

OPEXAACER THERAPEUTICS INC.

2635 TECHNOLOGY FOREST BLVD.ONE GATEWAY CENTER, SUITE 351 (300 WASHINGTON STREET)

THE WOODLANDS, TEXAS 77381NEWTON, MASSACHUSETTS 02458

NOTICE OF ANNUAL MEETING OF SHAREHOLDERS

TO BE HELD MAY 16, 201614, 2018

The Annual Meeting of shareholders of OpexaAcer Therapeutics Inc. will be held on Monday, May 16, 2016,14, 2018, at 10:00 a.m. CentralPacific Time, at 2 Houston Center, 909 Fannin,the offices of Pillsbury Winthrop Shaw Pittman LLP, 12255 El Camino Real, Suite 2000, Houston, Texas 77010.300, San Diego, California 92130. Our shareholders are being asked to vote to:

These business items are described more fully in the Proxy Statement accompanying this Notice.

Only shareholders who owned common stock at the close of business on March 28, 201626, 2018 can vote at this meeting or any adjournments or postponements that may take place. All shareholders are cordially invited to attend the meeting in person. However, to assure your representation at the meeting, you are urged to mark, sign

and return the enclosed proxy as promptly as possible in the postage-prepaid envelope for that purpose or use one of the voting methods described in the attached materials. Your stock will be voted in accordance with the instructions you have given. Any shareholder attending the meeting may vote in person even if he or she has previously returned a proxy. Please note, however, that if your shares are held of record by a broker, bank or other nominee and you wish to attend and vote in person at the meeting, you must obtain from the record holder a legal proxy issued in your name.

By Order of the Board of Directors,

Neil K. Warma,Chris Schelling, President and Chief Executive Officer

Dated: April 11, 20169, 2018

The Board of Directors solicits the enclosed proxy. Your vote is important no matter how large or small your holdings. To assure your representation at the meeting, please complete, sign, date and promptly mail the enclosed proxy card in the postage-paid envelope provided or use one of the voting methods described in the attached materials.

Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to be held on May 16, 2016:14, 2018: This Proxy Statement and our 20152017 Annual Report on Form10-K are available at: www.cstproxy.com/opexatherapeutics/2016acertx/2018

OPEXAACER THERAPEUTICS INC.

PROXY STATEMENT

ANNUAL MEETING OF SHAREHOLDERS

TO BE HELD MAY 16, 201614, 2018

INFORMATION CONCERNING SOLICITATION AND VOTING

General

The enclosed proxy is solicited on behalf of our Board of Directors (“Board”) for use at the annual meeting of shareholders to be held on Monday, May 16, 2016,14, 2018, at 10:00 a.m. CentralPacific Time (the “Annual Meeting”), or at any adjournment or postponement of this meeting, for the purposes set forth in this Proxy Statement and in the accompanying Notice of Annual Meeting of Shareholders. The Annual Meeting will be held at 2 Houston Center, 909 Fannin,the offices of Pillsbury Winthrop Shaw Pittman LLP, 12255 El Camino Real, Suite 2000, Houston, Texas 77010.300, San Diego, California 92130. We intend to mail this Proxy Statement and accompanying proxy card to shareholders on or about April 11, 2016. 9, 2018.

The Board of OpexaAcer Therapeutics Inc., a Texas corporation, prepared this Proxy Statement for the purpose of soliciting proxies for our Annual Meeting of Shareholders. The terms “we,” “our,” the “Company” or “Opexa,“Acer,” refer to OpexaAcer Therapeutics Inc., a Texas corporation (NASDAQ: ACER). The term “Private Acer” refers to Acer Therapeutics Inc., a Delaware corporation and wholly owned subsidiary. Acer was formerly known as “Opexa Therapeutics, Inc.” prior to the September 19, 2017 merger between Acer, Private Acer and Opexa Merger Sub, Inc.

Availability of Annual Report on Form10-K

Accompanying this Proxy Statement is our Annual Report on Form10-K for the fiscal year ended December 31, 20152017 as filed with the Securities and Exchange Commission (the “SEC”). We make available, free of charge through our website (www.opexatherapeutics.com)(www.acertx.com), our annual reports on Form10-K, quarterly reports onForm 10-Q, current reports on Form8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), as soon as reasonably practicable after such documents are electronically filed with or furnished to the SEC. These reports can be found under “SEC Filings” through the “Investor Relations” section of our website. We will provide to any shareholder without charge, upon the written request of that shareholder, a copy of our Annual Report on Form10-K (without exhibits), including financial statements and financial statement schedules. Such requests should be addressed to Investor Relations, OpexaAcer Therapeutics Inc., 2635 Technology Forest Blvd.One Gateway Center, Suite 351 (300 Washington Street), The Woodlands, Texas 77381.Newton, Massachusetts 02458.

Voting

Before the meeting, you may vote your shares if they are registered directly in your name with our transfer agent, Continental Stock Transfer & Trust Company, by (i) completing, signing, dating and returning the enclosed proxy card (i) by mail in the postage paid envelope provided or (ii) using the Internet to vote your proxy 24 hours a day, 7 days a week. If you would like to vote electronically, have your proxy card in hand when you log on and follow the instructions included with your proxy card. You are encouraged to vote electronically by faxingInternet. If you vote by Internet, you do not need to return your card to (281) 872-8585.proxy card. Please follow the directions on your proxy card carefully.

If your shares are held in a brokerage account in the name of a bank, broker or other nominee (this is called “street name”), then you are the beneficial owner of the shares and these proxy materials are being forwarded to you by that organization. The organization holding your account is considered the shareholder of record for purposes of voting at the Annual Meeting. You have the right to direct your bank or broker on how to vote the

shares in your account, and you may also be able to vote by telephone or via the Internet depending on the voting procedures used by your broker. You may receive a separate voting instruction form with this Proxy Statement, or you may need to contact your broker, bank or other nominee to determine whether you will be able to vote electronically using the telephone or Internet.

Whether or not you plan to attend the meeting, however, we encourage you to vote your shares by proxy before the meeting. You may vote your shares at the meeting if you attend in person, even if you previously submitted a proxy card or voted by telephone or Internet. Whether or not you plan to attend the meeting, however, we encourage you to vote your shares by proxy before the meeting. Please note that if your shares are held in “street name” and you wish to vote at the meeting, you will not be permitted to do so unless you first obtain a legal proxy issued in your name from the broker, bank or nominee that holds your shares.

Revocability of Proxies

Any proxy given pursuant to this solicitation may be revoked by the person giving it at any time before its use by delivering to the Secretary of Opexa,Acer, at the address of our executive offices noted above, written notice of revocation or a duly executed proxy bearing a later date or by attending the Annual Meeting and voting in person. Attendance at the Annual Meeting will not, by itself, revoke a proxy.

1

Quorum, Abstentions and BrokerNon-Votes

Our common stock is the only type of security entitled to vote at the Annual Meeting. Only shareholders of record at the close of business on March 28, 201626, 2018 (the “Record Date”) will be entitled to notice of and to vote at the Annual Meeting. As of the Record Date, there were 6,982,9097,497,433 shares of common stock outstanding and entitled to vote. Each holder of record of shares of common stock on the Record Date will be entitled to one vote for each share held on all matters to be voted upon at the Annual Meeting. Shares of common stock may not be voted cumulatively.

Proxies properly executed, duly returned to us and not revoked will be voted in accordance with the specifications made. Where no specifications are given, such proxies will be voted:

It is not expected that any matters other than those referred to in this Proxy Statement will be brought before the Annual Meeting. If, however, any matter not described in this Proxy Statement is properly presented for action at the Annual Meeting, the person named as proxy in the enclosed form of proxy will have discretionary authority to vote according to his own discretion.

The required quorum for the transaction of business at the Annual Meeting is a majority of the issued and outstanding shares of our common stock entitled to vote at the Annual Meeting, whether present in person or represented by proxy. Our bylaws provide that unless otherwise provided by law or by our Restated Certificate of Formation, as amended, all matters other than the election of directors shall be decided by the affirmative vote of a majority of the shares of stock represented in person or by proxy at the Annual Meeting. Shares of common stock represented by a properly signed and returned proxy will be treated as present at the Annual Meeting for purposes of determining a quorum, regardless of whether the proxy is marked as casting a vote or abstaining.

The term “brokernon-vote” refers to shares held by a brokerage firm, bank or other nominee (for the benefit of its client) that are represented at the meeting, but with respect to which such broker or nominee is not instructed to vote on a particular proposal and does not have discretionary authority to vote on that proposal. Brokers and nominees do not have discretionary voting authority on certainnon-routine matters and accordingly may not vote on such matters absent instructions from the beneficial holder. Discretionary items are proposals considered “routine” under the rules of the New York Stock Exchange (also applicable to NASDAQ-listedNasdaq-listed companies), such as the ratification of the appointment of our independent auditors.Non-routine items for which brokers and nominees do not have discretionary voting power include the election of directors, the approval of our Amended and Restated 2010 Stock Incentive Planthe proposed provisions in the Delaware certificate of incorporation, the approval of the Reincorporation and the approval of the compensation of our Named Executive Officers.2018 Stock Incentive Plan.

If you hold your shares in “street name” or through a broker it is important that you direct your broker how to vote your shares.

Vote Required

Proposal 1. Directors are elected by a plurality of the affirmative votes cast by those shares of common stock present in person, or represented by proxy, and entitled to vote at the Annual Meeting. This means the sixseven nominees for directors receiving the highest number of affirmative votes will be elected. Proxies marked to “Withhold Authority” will not affect the election of a candidate who receives a plurality of votes. The election of directors is a matter on which a broker or other nominee is generally not empowered to vote using discretion, and therefore, brokernon-votes may exist but will have no effect on the outcome of the election of candidates for directors. Shareholders may not cumulate votes in the election of directors. We urge you to provide any necessary voting instructions to your broker or nominee if you hold your shares in street name in order for your vote to be considered for this proposal.

Proposal 2Proposals 2A, 2B, 2C, 2D and 2E. Approval of our Amended and Restated 2010 Stock Incentive Planthe proposed revisions of the proposed certificate of incorporation under Delaware law in connection with the Reincorporation requires the affirmative vote of the holders of a majority of the outstanding shares of common stock entitled to vote. Proposals 2A, 2B, 2C, 2D and 2E are matters on which a broker or other nominee is generally not empowered to vote using discretion, and therefore, abstentions and broker non-votes may exist with respect to these proposals. Accordingly, we urge you to provide any necessary voting power presentinstructions to your broker or represented by proxynominee if you hold your shares in street name in order for your vote to be considered for these proposals. Abstentions will be counted toward the vote total and voting atwill have the Annual Meeting. same effect as “Against” votes.

Proposal 23. Approval of the Reincorporation requires the affirmative vote of the holders of a majority of the outstanding shares of common stock entitled to vote. Proposal 3 is a matter on which a broker or other nominee is generally not empowered to vote using discretion, and therefore, abstentions and brokernon-votes may exist with respect to this proposal. Accordingly, we urge you to provide any necessary voting instructions to your broker or nominee if you hold your shares in street name in order for your vote to be considered for this proposal. Abstentions will be counted toward the vote total and will have the same effect as “Against” votes.

2

Proposal 34. Because the proposal to approve the compensationApproval of our Named Executive Officers asks for a non-binding, advisory2018 Stock Incentive Plan requires the affirmative vote there is no “required vote” that would constitute approval. We value the opinions expressed by our shareholders in this advisory vote, and our Compensation Committee, which is responsible for overseeing and administering our executive compensation programs, will consider the outcome of the holders of a majority of the voting power present or represented by proxy and voting at the Annual Meeting. Proposal 4 is a matter on which a broker or other nominee is generally not empowered to vote when designing our compensation programsusing discretion, and making future compensation decisions for our Named Executive Officers. Abstentionstherefore, abstentions and brokernon-votes may exist with respect to this proposal. Accordingly, we urge you to provide any necessary voting instructions to your broker or nominee if you hold your shares in street name in order for your vote to be considered for this proposal. Abstentions will not affect the outcome of this advisory vote.outcome.

Proposal 45. Ratification of the appointment of MaloneBailey, LLPWolf & Company, P.C. as our independent auditors requires the affirmative vote of the holders of a majority of the voting power present or represented by proxy and voting at the Annual Meeting. The ratification of the appointment of the independent auditors is a matter on which a

broker or other nominee is generally empowered to vote, and therefore, brokernon-votes are not expected to exist with respect to this proposal. Abstentions will not affect the outcome.

Solicitation

The cost of soliciting proxies will be borne by Opexa.Acer. In addition to soliciting shareholders by mail and through our regular employees, we will request that banks and brokers and other persons representing beneficial owners of the shares forward the proxy solicitation material to such beneficial owners and we may reimburse these parties for their reasonableout-of-pocket costs. We may use the services of our officers, directors and others to solicit proxies, personally or by telephone, facsimile or electronic mail, without additional compensation. We have retained Advantage Proxy to assist us in soliciting proxies using the means referred to above. We will pay the fees of Advantage Proxy, which we expect to be approximately $5,500, plus reimbursement ofout-of-pocket expenses.

If you need additional copies of this Proxy Statement or the enclosed proxy card, or if you have other questions about the proposals or how to vote your shares or to obtain directions to attend the meeting and vote in person, you may contact our proxy solicitor, Advantage Proxy, at(877) 870-8565 (toll free).

Shareholder Proposals

Proposals of shareholders that are intended to be presented at our 20172019 Annual Meeting of Shareholders and the proxy materials for such meeting must comply with the requirements of SEC Rule14a-8 and must be received by our Secretary no later than March 25, 2017December 10, 2018 in order to be included in the Proxy Statement and proxy materials relating to that meeting. Moreover, with respect to any proposal by a shareholder not seeking to have the proposal included in the Proxy Statement but seeking to have the proposal considered at our next annual meeting, pursuant to our bylaws such shareholder must provide written notice of such proposal so that it is received by our Secretary at our principal executive offices not less than 50 days nor more than 90 days prior to the date of such meeting; provided, however, that in the event that less than 75 days’ notice of the date of the meeting is given to shareholders, notice by the shareholder to be timely must be received no later than the close of business on the 15th day following the date on which notice of the date of the annual meeting was mailed. If the shareholder fails to give notice by this date, then the persons who are appointed as proxies may exercise their discretionary voting authority with respect to such proposals, even if the shareholders have not been advised of the proposal. In addition, shareholders must comply in all respects with the rules and regulations of the SEC then in effect and the procedural requirements of our bylaws.

Dissenter’sDissenters’ Rights

Neither Texas law nor our Restated Certificate of Formation or bylaws provide our shareholders with dissenters’ rights in connection with the matters described in this Proxy Statement.

PROPOSAL 1

ELECTION OF DIRECTORS

The Board of Directors currently consists of sixseven members, each with a term expiring at the 20162018 Annual Meeting. Our Board of Directors was entirely reconstituted at the closing of the September 19, 2017 merger between the Company (formerly known as Opexa Therapeutics, Inc.), Acer Therapeutics Inc., a Delaware corporation (“Private Acer”), and Opexa Merger Sub, Inc. The Nominating Committee of the Board has recommended, and the Board has nominated, the sixseven incumbent directors for election at the Annual Meeting. The shares represented by the enclosed proxy will be voted for the election as directors of the sixseven nominees named below to serve until the 20172019 Annual Meeting or until their successors have been duly elected and qualified. All of the nominees have indicated to us that they will be available to serve as directors. If any of the nominees becomes unavailable for any reason or if a vacancy should occur before the election (which events are not anticipated), the shares represented by the enclosed proxy may be voted for such other person or persons recommended by the Board as may be determined by the holders of the proxy. There are no family relationships among our executive officers and directors.

Director Nominees

Individuals nominated for election are:

Biographical information for our directors is set forth below:

Timothy C. BarabeStephen J. Aselage has served as Chairman of the Board since the completion of the merger in September 2017. Since October 2015, Mr. Aselage has served as the chairman of Private Acer’s board of directors. He has served as president and chief executive officer of Retrophin, Inc., a Nasdaq-listed, fully integrated biopharmaceutical company, since November 2014 and as a member of its board of directors since October 2012. From May 2014 to November 2014, Mr. Aselage served as the chief operations officer and interim chief executive officer of Retrophin. Prior to joining Retrophin, he held a variety of roles at BioMarin, as executive vice president and chief business officer from December 2009 to September 2012 and senior vice president of global commercial development from July 2005 to December 2009. He has also held leadership roles at Cell Therapeutics, Inc., Sangstat Medical Corporation, Advanced Tissue Sciences, Inc. and Genentech, Inc. Mr. Aselage earned a B.S. in biology from the University of Notre Dame. Acer believes that Mr. Aselage is qualified to serve on our Board of Directors due to his extensive experience in the pharmaceuticals and biotechnology industry, which will enable him to contribute important insights to our Board of Directors on strategic leadership and drug commercialization matters.

Jason Amello has served as a Director since March 2014. He retiredthe completion of the merger in September 2017. Since September 2013, as Executive Vice President and Chief Financial Officer of Affymetrix, Inc. Previously, from July 2006 until March 2010, he was Senior Vice President and Chief Financial Officer of Human Genome Sciences, Inc. Mr. Barabe served as Chief Financial Officer of Regent Medical Limited, a U.K.-based, privately owned, surgical supply company, from 2004 to 2006. He was with Novartis AG from 1982 through August 2004, where he served in a succession of senior executive positions in finance and general management, most recently as the Chief Financial Officer of Sandoz GmbH, the generic pharmaceutical subsidiary of Novartis. Mr. Barabe serves on the boards of: ArQule, Inc., a Boston-based, NASDAQ-listed biotech company; Vigilant Biosciences, Inc., a private medical device company; Veeva Systems Inc., a cloud based software company focusing on the life sciences industry; and Project Open Hand, a non-profit organization. He received his B.B.A. degree from the University of Massachusetts (Amherst) and his M.B.A. from the University of Chicago. Mr. Barabe has extensive experience as a senior financial executive of life sciences companies, giving him valuable operational and financial experience, including in the international setting, and knowledge of both the pharmaceutical and biotech industries.

Hans-Peter Hartung, M.D.Amello has served as a Director since March 2014senior vice president, chief financial officer and as a membertreasurer of our Scientific Advisory Board since 2010. He has served as a professor and Chairman of the Department of Neurology at Heinrich Heine University of Düsseldorf, Germany since 2001. Dr. Hartung earned his M.D. degree from the University of Düsseldorf and received post-graduate training in immunology, neurology and neuroimmunology at the University of Mainz, Germany and the University of Düsseldorf. He is a member of several international and national medical societies, serves on various executive and academic boards, as well as on the editorial board of a number of international medical journals (including past-president of ECTRIMS, the European Neurological Society, the International Society for Neuroimmunology, the International Federation of Multiple Sclerosis Societies and the World Health Organization Advisory Board on Multiple Sclerosis). He has also been published extensively in the field of neuroimmunological disorders. Dr. Hartung has extensive experience in the field of drug discovery and development, is a leader in the field of clinical immunology and has broad leadership experience on various boards.

Gail J. Maderis has served as a Director since October 2011. Ms. Maderis has served as the President and Chief Executive Officer of Antiva Biosciences, Inc. since July 2015. Formerly, Ms. Maderis served as President and CEO of BayBio (Bay Area Bioscience Association), an independent, non-profit trade association serving the life sciences industry in Northern California, from October 2009 to March 2015, and also served on BayBio’s board from 2004 to March 2015. From July 2003 to June 2009, Ms. Maderis served as President and CEO of Five PrimeAkebia Therapeutics, Inc., a biotechnologybiopharmaceutical company focused on the development and commercialization of novel therapeutics for patients with kidney disease. From May 2012 to May 2013, he served as executive vice president, chief financial officer and treasurer of ZIOPHARM Oncology, Inc., a biopharmaceutical company focused on the discovery and development of innovative protein and antibody drugs, and served as a director until 2010. Priornew cancer therapies. From April 2000 to that, Ms. MaderisJune 2011, Mr. Amello held general managementvarious positions at Genzyme Corporation, from 1997 to 2003, including foundera biotechnology company focused on development of

therapeutics for multiple diseases and president of Genzyme Molecular Oncology, a publicly traded division of Genzyme, and corporatedisorders, most recently as senior vice president, corporate controller, and chief accounting officer. Earlier in his career, Mr. Amello spent 10 years in the business advisory and assurance practice of Genzyme Corporation. Ms. Maderis has served asDeloitte, serving in various roles of increasing responsibility through senior manager. He currently serves on the board of directors of the New England Baptist Hospital, an orthopedic specialty hospital. Mr. Amello earned a directorB.A. in accounting from Boston College and is a Certified Public Accountant in the Commonwealth of NovaBay Pharmaceuticals, Inc. since October 2010. Ms. Maderis has also been a memberMassachusetts. Acer believes that Mr. Amello is qualified to serve on our Board of several private company boards. Ms. Maderis received a B.S. degree in business from the University of California at Berkeley and an M.B.A. from Harvard Business School. Ms. Maderis hasDirectors due to his extensive experience as a senior executive ofin finance related to managing life sciences companies, giving her valuable operationalwhich will enable him to contribute important insights to our Board of Directors on financial matters toward the continued growth and industry experience and leadership skills, as well as an extensive networkexpansion of contacts related to financing, partnering and support services in the biotech industry and visibility into business and policy trends that impact the biopharmaceutical industry.

4

Michael S. Richmanhas served as a Director since June 2006. Mr. Richman has served as President and Chief Executive Officer of NextCure, Inc. since December 2015. Mr. Richman served as president and chief executive officer of Amplimmune, Inc. from July 2008 to July 2015. Mr. Richman served as president and chief operating officer of Amplimmune, Inc. from May 2007 to July 2008. From April 2002 to May 2007, Mr. Richman served as executive vice president and chief operating officer of MacroGenics, Inc. Mr. Richman joined MacroGenics, Inc. in 2002 with approximately 20 years’ experience in corporate business development within the biotechnology industry. Mr. Richman served as a director of Cougar Biotechnology from June 2006 to July 2009. Mr. Richman obtained his B.S. in Genetics/Molecular Biology at the University of California at Davis and his MSBA in International Business at San Francisco State University. He has extensive experience in business development and strategic planning for life science companies, as well as executive leadership and management experience.Acer.

Scott B. SeamanHubert Birner, Ph.D., MBA has served as a Director since the completion of the merger in September 2017. Since April 2006. Mr. Seaman2017, Dr. Birner has served as a member of Private Acer’s board of directors. Since 2000, he has served in a variety of roles for over five yearsTVM Capital, an independent affiliation of international private equity and venture capital firms, where he currently serves as (i) the executive directormanaging partner of TVM Capital and treasurerTVM Life Science Management. Dr. Birner currently serves as the chairman of the Albertboards of directors of Argos Therapeutics, Inc., a Nasdaq-listed immuno-oncology company, and Margaret Alkek FoundationNOXXON Pharma N.V., a EuroNext Growth Paris-listed biopharmaceutical company, and as a member of Houston, Texas,the board of directors of Proteon Therapeutics, Inc., a private foundation primarily supporting biomedical researchNasdaq-listed biopharmaceutical company, as well as a number of privately held life science companies. Prior to his tenure at TVM Capital, Dr. Birner held roles at Zeneca Group PLC and institutionsMcKinsey & Company. He served as the vice chairman of Evotec AG, a Frankfurt Stock Exchange-listed company focused on the discovery and development of small molecule drugs, from 2005 to 2013, and as a director of Probiodrug AG, a Euronext Amsterdam-listed biopharmaceutical company, from 2014 to 2015. Dr. Birner earned a Ph.D. in biochemistry from Ludwig-Maximilian University of Munich and an MBA from Harvard Business School. Acer believes that Dr. Birner is qualified to sit on our Board of Directors due to his extensive experience in the Texas Medical Centerlife sciences industry, both as an investor and a director, which will enable him to help guide Acer in Houston, Texas, (ii)future capital raising efforts.

John M. Dunn has served as a Director since the completion of the merger in September 2017. Since October 2015, Mr. Dunn has served as a member of Private Acer’s board of directors. Since November 2014, he has served as general counsel of Vital Therapies, Inc., a biotherapeutic company. Prior to joining Vital Therapies, Mr. Dunn was a consultant from February 2012 to November 2014, an executive vice president of Biogen Idec, Inc., now Biogen, Inc., a biotechnology company, from November 2003 to January 2012, where he was the head of that firm’s corporate venture group, and general counsel of IDEC Pharmaceuticals from 2002 until its merger with Biogen in November 2003. Mr. Dunn earned a B.S. in finance and a J.D. from the University of Wyoming. Acer believes that Mr. Dunn is qualified to serve on our Board of Directors as a result of his deep experience relating to corporate governance and regulatory and financing matters in the pharmaceuticals and biotechnology industry, which will enable him to contribute important strategic insights to our Board of Directors.

Michelle Griffinhas served as a Director since the completion of the merger in September 2017. Since April 2013, Ms. Griffin has served as the principal of Pacific Biotechnology Consulting Group, a firm providing consulting services to biotechnology companies and their boards of directors. Prior to her time with Pacific Biotechnology Consulting Group, Ms. Griffin served from January 2011 to March 2013 as executive vice president, operations and chief financial officer of Chaswil Ltd.OncoGenex Pharmaceuticals, Inc. Ms. Griffin served as a member of the board of directors and as chair of the audit committee for PhaseRx, Inc. from 2016 until its acquisition by Roivant Sciences GmbH in 2018, OncoGenex Pharmaceuticals, Inc. from 2008 to 2011, and Sonus Pharmaceuticals, Inc. (subsequently acquired by OncoGenex) from 2004 to 2008, and during various periods from 1997 to 2011 served in the capacity of Chief Financial Officer for Trubion Pharmaceuticals, Inc., Dendreon Corporation and Corixa Corporation. Ms. Griffin earned her B.S. in marketing from George Mason University and her M.B.A. with a private family managementspecialization in finance and international business from Seattle University. Acer believes that Ms. Griffin is qualified to serve on our Board of Directors as a result of her extensive operational experience in the biotechnology industry and deep experience in public company (iii) secretaryfinancial matters, which will enable her to contribute important insights to our Board of Directors on drug development and treasurerfinancial matters.

Luc Marengere, Ph.D.has served as a Director since the completion of M & A Propertiesthe merger in September 2017. Since April 2016, Dr. Marengere has served as a member of Private Acer’s board of directors. He serves as managing partner of TVM Life Science Venture VII, L.P, a venture capital fund, which he joined in March 2012. From October 2001 to March 2012, Dr. Marengere was a managing general partner with VG Partners, a merchant bank. He serves on the boards of directors of a number of privately held life science companies. From January 2015 to March 2017, Dr. Marengere also served on the board of directors of CoLucid Pharmaceuticals, Inc., a ranchingNasdaq-listed biopharmaceutical company. He has also held roles at CDP Capital – Technology Ventures and real estate concern, (iv) managing memberMDS Capital Corp. Dr. Marengere earned a Ph.D. from the University of ICT Development LLC, which is the managing member of ICT Holdings LLC,Toronto, an energy services supplier, for which he serves as president, and (v) director of Somebody Cares America. In March 2013, Mr. Seaman was elected a director of Gradalis, Inc., a privately held clinical stage biotechnology company developing cancer focused immunotherapies. In June 2013, Mr. Seaman became a director of Strike Bio, Inc., a privately held clinical stage biotechnology company developing gene interference therapeutics. Mr. Seaman received a bachelor’s degreeM.S. in business administrationendocrinology from Bowling Green StateQueen’s University and a B.S. in biochemistry from the University of Ottowa. Acer believes that Dr. Marengere is a certified public accountant. Mr. Seaman hasqualified to serve on our Board of Directors due to his extensive experience in overall financial managementfunding and corporate development, combined with operationalmanaging life sciences companies, which will enable him to contribute valuable insights regarding the continued growth and corporate governance experience.expansion of Acer.

Neil K. WarmaChris Schelling has served as a Director and as our President and Chief Executive Officer since June 2008the completion of the merger in September 2017. Mr. Schelling founded Private Acer in December 2013 and has served as a Directordirector since September 2008. He has alsothat time. From December 2013 to February 2016, he served as Acting Chief Financial OfficerPrivate Acer’s chief operating officer, and since MarchFebruary 2016 and previouslyhas served as our Acting Chief Financial Officer from March 2009 to August 2012. From July 2004 to September 2007, Mr. Warma served asPrivate Acer’s president and chief executive officerofficer. Mr. Schelling also founded Apanii Consulting, LLC, a pharmaceutical and biotechnology consulting company, in December 2012 and currently serves as Apanii’s chief executive officer. Prior to founding Apanii Consulting, he served as executive director of Vironstrategic marketing at BioMarin Pharmaceutical Inc., or BioMarin, a Nasdaq-listed biotechnology company, from May 2006 to October 2012. He has also held roles at Abgenix, Inc., Cell Therapeutics, Inc., Stanford Research Institute Consulting and Organon. Mr. Schelling earned a privately-held clinical stage biopharmaceutical company. From 2000 to 2003B.A. in biology from Carroll College. Acer believes that Mr. Warma was co-founder and presidentSchelling’s role in the founding of MedExact USA, Inc., an Internet company providing clinical information and services to physicians and pharmaceutical companies. From 1992 to 2000, Mr. Warma held senior positions of increasing responsibility at Novartis Pharmaceuticals (previously Ciba-Geigy Ltd.) at its corporate headquarters in Basel, Switzerland. While at Novartis, Mr. Warma servedAcer, his experience as the Head of International Pharma Policy & Advocacy and in senior management within global marketing where he worked on the international launch of a gastrointestinal product. Mr. Warma obtained an honors degree specializing in Neuroscience from the University of Toronto and an International M.B.A. from the Schulich School of Management at York University in Toronto. As our President andAcer’s Chief Executive Officer Mr. Warma is directly involved in all aspects of our operations. He has extensiveand his experience in corporate business development within the biopharmaceuticalbiotechnology industry in additionqualify him to executive leadership and management experience.

Theserve on our Board of Directors recommends a voteDirectors.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” the election of each the above nominees.THE ELECTION OF EACH THE ABOVE NOMINEES

Board and Shareholder Meetings

Members of the Board are encouraged to attend our Annual Meeting of shareholders; however, attendance is not mandatory. All sixBecause of our directors attended the 2015merger between Private Acer and what was then known as Opexa Therapeutics, Inc., there was no Annual Meeting of shareholders. Forshareholders in 2017. During the fiscal year endedperiod of September 19, 2017 (the effective date of the merger and the date our Board of Directors was reconstituted with the current members) to December 31, 2015,2017, the Acer Board held one meeting, and each director attended at least 75% of the total number of meetings held by the Board and all committees on which such director served during the period he or she was a director. During the period of January 1, 2017 to September 19, 2017, the Opexa Board held tenseven meetings, and each director attended at least 75% of the total number of meetings held by the Board and all committees on which such director served during the period he or she was a director, in 2015, except for Dr. Hans-Peter Hartung.

Director Independence

The Board has determined that Ms. Griffin, Drs. Birner and Marengere, and Messrs. Barabe, RichmanAmello, Aselage and Seaman, Dr. Hartung and Ms. MaderisDunn are each an independent director within the meaning of NASDAQNasdaq listing standards, which directors constitute a majority of the Board. The Board has determined that each member of the Board’s Audit, Compensation and Nominating and Corporate Governance Committees is independent (or similarly designated) based on the Board’s application of the standards of NASDAQNasdaq and the rules and regulations promulgated by the SEC or the Internal Revenue Service, as appropriate for such committee membership.

Committees of the Board of Directors

We currently have a standing Audit Committee, Compensation Committee, and Nominating and Corporate Governance Committee. The Board has adopted written charters for each of the committees, and copies of the charters are available on our website at www.opexatherapeutics.com.www.acertx.com. Please note that the information contained on our website is not incorporated by reference in, or considered to be a part of, this document.

5

The current members of these committees are as follows:

Audit Committee

The Audit Committee of the Board currently consists of Messrs. SeamanMs. Griffin (chair) and BarabeMessrs. Amello and Ms. Maderis,Dunn, each of whom is an independent,non-employee director. The Audit Committee selects, on behalf of our Board, an independent public accounting firm to audit our financial statements, discusses with the independent auditors their independence, reviews and discusses the audited financial statements with the independent auditors and management, recommends to our Board whether the audited financials should be included in our annual reports to be filed with the SEC, and oversees management’s identification, evaluation, and mitigation of major risks to Opexa.Acer. The Audit Committee operates pursuant to a written charter. During the last fiscal year, the Audit Committee held four meetings.

All of the members of the Audit Committee arenon-employee directors who: (1) met the criteria for independence as required by NASDAQNasdaq listing standards and as set forth in Rule10A-3(b)(1) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”);Act; (2) did not participate in preparation of our financial statements during the past three years; and (3) are able to read and understand fundamental financial statements, including a balance sheet, income statement, and cash flow statement. The Board has determined that Ms. Griffin and Messrs. SeamanAmello and Barabe and Ms. MaderisDunn each, individually, qualifyqualifies as an “audit committee financial expert” as defined in SEC rules and regulations and also possesses the financial sophistication and requisite experience as required under NASDAQNasdaq listing standards.

Compensation Committee

The Compensation Committee of the Board currently consists of Messrs. BarabeAselage (chair) and RichmanMarengere and Ms. Maderis,Griffin, each of whom is an independent director. The Compensation Committee reviews and approves (1) the annual salaries and other compensation of our executive officers and (2) individual stock and stock option grants. The Compensation Committee also provides assistance and recommendations with respect to our compensation policies and practices, and assists with the administration of our compensation plans. In evaluating executive officer compensation, the Compensation Committee may retain the services of compensation consultants and considers recommendations from the Chief Executive Officer with respect to compensation of the other executive officers. TheFrom time to time and as it determines necessary or desirable, the Compensation Committee also periodically reviewsmay retain the services of an independent compensation consultant to advise on compensation-related matters relating to the executive officers and independent directors. Prior to the September 2017 merger with Opexa, Private Acer retained the services of Radford (which is a part of Aon Hewitt, a business unit of Aon plc) as an independent compensation consultant to (i) evaluate Private Acer’s executive compensation program and recommend a course of action for

consideration in preparation for becoming a public company and (ii) assess Private Acer’snon-employee director compensation practices against a selection of peer group companies and make a recommendation relating thereto. Subsequent to closing of the merger with Opexa in September 2017, our Compensation Committee reviewed the analysis and reports prepared by Radford and provided to Private Acer and implemented certain compensation adjustments for our executives andnon-employee directors. In reviewing the reports prepared by Radford for Private Acer, our Compensation Committee considered the independence of Radford pursuant to SEC rules and the corporate governance rules of The Nasdaq Stock Market and concluded that no conflict of interest exists that would prevent Radford from independently advising the Compensation Committee. During the last fiscal year, the Compensation Committee held three meetings.engaged in discussions without formally meeting, to build a consensus on various related matters, and all formal actions were taken by the Board of Directors.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee of the Board currently consists of Ms. MaderisMessrs. Dunn (chair), Aselage and Messrs. Richman and Seaman,Marengere, each of whom was determined by the Board to be an independent director. The Nominating and Corporate Governance Committee assists our Board in fulfilling its responsibilities by: identifying and approving individuals qualified to serve as members of our Board, selecting director nominees for our annual meetings of shareholders, evaluating the performance of our Board, and developing and recommending to our Board corporate governance guidelines and oversight procedures with respect to corporate governance and ethical conduct. In identifying and evaluating candidates, the committee takes into consideration the criteria approved by the Board and such other factors as it deems appropriate. We do not have a formal diversity policy, and the committee considers a broad range of factors in evaluating prospective director nominees. These factors may include judgment, skill, diversity, experience with businesses and other organizations of comparable size, the interplay of the candidate’s experience with the experience of other Board members, and the extent to which the candidate would be a desirable addition to the Board and any committees of the Board. The Committee will consider properly submitted shareholder nominations for candidates for the Board. Following verification of the shareholder status of persons proposing candidates, recommendations will be aggregated and considered by the Committee. If any materials are provided by a shareholder in connection with the nomination of a director candidate, such materials will be forwarded to the Committee. During the last fiscal year, the Nominating and Corporate Governance Committee held two meetings.engaged in discussions without formally meeting, to build a consensus on various related matters, and all formal actions were taken by the Board of Directors.

6

Risk Oversight

A fundamental part of risk management is not only understanding the risks a company faces and what steps management is taking to manage those risks, but also understanding what level of risk is appropriate for each company. Our Board is actively involved in oversight of risks that could affect Opexa.Acer. The full Board has retained the responsibility for general oversight of risks, but the Audit Committee primarily oversees those risks that may directly or indirectly impact our financial statements. The Board’s role in the risk oversight process includes receiving reports from members of management and the Audit Committee on areas of material risk to Opexa,Acer, including operational, financial, legal and regulatory, and strategic risks which enable it to better understand our risk identification, management and mitigation strategies.

Board Leadership Structure

The Board evaluates its leadership structuredoes not have a policy on an ongoing basis according to whatwhether the same person should serve as both the chief executive officer and chairman of the Board considersor, if the roles are separate, whether the chairman should be selected from thenon-employee directors or should be an employee. The Board believes that it should have the flexibility to be best for Opexamake these determinations at any given point in time in the way that it believes best to provide appropriate leadership for the Company at that time. Because we areThe Board believes that its current leadership structure, with Mr. Aselage serving as a clinical stage company, we do not currently have a separate role fornon-employee Chairman of the Board. OurBoard and Mr. Schelling serving as Chief Executive Officer, is in consultation with the Board, sets our strategic direction,best

interest of shareholders at this time. The current structure ensures a greater role for the independent directors in the oversight of the Company and he managesactive participation of the day to day leadershipindependent directors in setting agendas and performanceestablishing priorities and procedures for the work of Opexa. Given our current size and stage of development, the Board believes this leadership structure is appropriate for Opexa.Board.

20152017 Director Compensation

The following table presents summary information regarding compensation of thenon-employee members of our Board of Directors who served during any part of the fiscal year ended December 31, 2015.2017.

7

Standard Compensation Arrangements

EmployeeOutside directors dowho are not affiliated with TVM Capital Life Sciences receive compensation for their service on our Board of Directors that consists of cash compensation and equity awards as described below. A director who is also our employee does not receive any additional compensation for services as a member of our Board. We reimburse our directors for travel and lodging expenses in connection with their attendance at Board and committee meetings. Our standard annual compensation arrangements for our non-employee directors consistsconsist of the following, valued at $55,000:following:

Board Member Cash Compensation:

Additional Committee Chair Cash Compensation:

Additional Committee Member Cash Compensation:

Board Member Equity Compensation:

Communications to the Board of Directors

The Board has adopted the following policy for shareholders who wish to communicate any concern directly with the Board. Shareholders may mail or deliver their communication to our principal executive offices, addressed as follows:

Addressee (*)

c/o Secretary

OpexaAcer Therapeutics Inc.

2635 Technology Forest Blvd.One Gateway Center, Suite 351 (300 Washington Street)

The Woodlands, TX 77381Newton, MA 02458

*Addressees: Board of Directors; Audit Committee of the Board of Directors; Nominating and Corporate Governance Committee of the Board of Directors; Compensation Committee of the Board of Directors; name of individual director.

Copies of written communications received at such address will be forwarded to the addressee as soon as practicable.

AUDIT COMMITTEE REPORT

The Audit Committee of the Board of Directors currently consists of Ms. Griffin and Messrs. SeamanAmello and Barabe and Ms. Maderis,Dunn, all of whom are independent,non-employee directors.

The Audit Committee operates under a written charter adopted by the Board, which is evaluated annually. The Audit Committee selects, evaluates and, where deemed appropriate, replaces the Company’s independent auditors. The Audit Committee alsopre-approves all audit services, engagement fees and terms, and all permittednon-audit engagements, except for certain de minimis amounts.

Management is responsible for the Company’s internal controls and the financial reporting process. The Company’s independent auditors are responsible for performing an independent audit of Opexa’sAcer’s consolidated financial statements in accordance with auditing standards generally accepted in the United States of America and issuing a report on Opexa’sAcer’s consolidated financial statements. The Audit Committee’s responsibility is to monitor and oversee these processes.

In this context, the Audit Committee has reviewed the Company’s audited financial statements for fiscal 20152017 and has met and held discussions with management and MaloneBailey, LLP,Wolf & Company, P.C., the Company’s independent auditors. Management represented to the Audit Committee that the Company’s consolidated financial statements for fiscal 20152017 were prepared in accordance with accounting principles generally accepted in the United States of America, and the Audit Committee discussed the consolidated financial statements with the independent auditors. The Audit Committee also discussed with MaloneBailey, LLPWolf & Company, P.C. the matters required to be discussed by Auditing Standard No. 16,Communications with Audit Committees, as adopted by the Public Company Accounting Oversight Board (PCAOB).

MaloneBailey, LLPWolf & Company, P.C. also provided to the Audit Committee the written disclosures and the letter required by applicable requirements of the PCAOB regarding the independent auditors’ communications with the Audit Committee concerning independence, and the Audit Committee discussed with MaloneBailey, LLPWolf & Company, P.C. the accounting firm’s independence.

Based upon the Audit Committee’s discussion with management and MaloneBailey, LLP,Wolf & Company, P.C., and the Audit Committee’s review of the representation of management and the report of MaloneBailey, LLPWolf & Company, P.C. to the Audit Committee, the Audit Committee recommended to the Board of Directors that the audited consolidated financial statements be included in the Company’s Annual Report on Form10-K for the fiscal year ended December 31, 20152017 filed with the SEC.

Submitted by the Audit Committee of the

Board of Directors of OpexaAcer Therapeutics Inc.:

Scott B. Seaman,Michelle Griffin, Chair

Timothy C. BarabeJason Amello

Gail J. MaderisJohn M. Dunn

OVERVIEW OF PROPOSALS 2A, 2B, 2C, 2D, 2E AND 3

9In connection with the Reincorporation which is the subject of Proposal 3 below, subject to the approval of shareholders, our existing Restated Certificate of Formation, as amended (the “Texas Charter”), and our existing Amended and Restated Bylaws, as amended (the “Texas Bylaws”), will be replaced by a new certificate of incorporation (the “Delaware Charter”) and new bylaws (the “Delaware Bylaws”). We intend to implement certain changes described below as compared to the current Texas Charter and Texas Bylaws, and, pursuant to Proposals 2A, 2B, 2C, 2D and 2E, shareholders are asked to consider and to vote to approve certain provisions which are included in the proposed Delaware Charter and Delaware Bylaws.

If the Reincorporation is approved and implemented, the provisions of the Delaware Charter and Delaware Bylaws will depend upon whether any or all of Proposals 2A, 2B, 2C, 2D and 2E are approved. If a proposal to include a certain provision is approved, the Delaware Charter and Delaware Bylaws will include a provision substantively as described in the proposal. If a proposal to include a certain provision is not approved, Proposals 2A, 2B, 2C, 2D and 2E describe the impact on the Delaware Charter and Delaware Bylaws, as applicable.

Background

Proposals 2A, 2B, 2C, 2D and 2E set forth below (i) are intended to supplement, amend or remove provisions in our governing documents as part of our Reincorporation in Delaware that Acer believes are unnecessary for the protection of the Company or the shareholders and/or (ii) are intended to provide the Board of Directors with flexibility to take actions that it believes to be in the best interest of Acer and the best interest of our shareholders. The Board believes that it is appropriate to vest in the Board of Directors the powers sufficient to provide it with the flexibility it needs to timely and effectively direct the Company and its management and development.

If the Reincorporation is approved by the shareholders and subsequently consummated, we anticipate that we will continue to review the terms and provisions of the Delaware Charter and the Delaware Bylaws on an ongoing basis to ensure that the Board of Directors has appropriate corporate governance flexibility and to ensure that Acer maintains appropriate shareholder protections. These reviews could result in the Board of Directors making the determination that the addition of certain provisions to, deletion of certain provisions from, or the amendment of certain provisions in, the Delaware Charter or the Delaware Bylaws would be in the Company’s best interest. Depending on the provisions that are being added, amended or deleted, shareholder approval may or may not be required. However, any decisions the Board of Directors makes with respect to an amendment of the Delaware Charter or the Delaware Bylaws are subject to express statutory duties under Delaware law, which require that each of the directors, in carrying out his or her responsibilities as a director, acts in good faith, with a reasonable belief that his or her actions are in the Company’s best interests, and with the care of an ordinarily prudent person in a like position under similar circumstances.

The proposed form of Delaware Charter and Delaware Bylaws are attached as Appendix D and Appendix E to this Proxy Statement. These forms assume that all of the proposed provisions described in Proposals 2A, 2B, 2C, 2D and 2E below will be approved.

Board Recommendation

THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” APPROVAL OF EACH OF

THE PROPOSED PROVISIONS OF THE PROPOSED DELAWARE CHARTER AND DELAWARE

BYLAWS (PROPOSALS 2A, 2B, 2C, 2D AND 2E)

PROPOSAL 22A

APPROVAL OF AMENDEDTHE PROPOSED PROVISION IN THE DELAWARE CHARTER

TO PERMIT STOCKHOLDER ACTION ONLY AT A DULY CALLED MEETING AND RESTATED 2010

TO PROHIBIT ACTION BY WRITTEN CONSENT OF STOCKHOLDERS

Proposed Provision

Proposal 2A is a provision in the Delaware Charter to permit stockholder action only at a duly called meeting and to prohibit action by written consent of stockholders. If Proposal 2A is approved, the Delaware Charter will include the following provision:

“No action required or permitted to be taken at any annual or special meeting of the stockholders may be taken without a meeting and the power of stockholders to consent in writing, without a meeting, to the taking of any action is specifically denied.”

Under Delaware law, unless otherwise provided in the certificate of incorporation, any action that can be taken at a meeting of the stockholders can be taken without such meeting if written consent thereto is signed by the holders of outstanding stock having the minimum number of votes necessary to authorize or take such action at a meeting at which all shares entitled to vote thereon were presented and voted.

Our existing Texas Charter does not address this provision. Our existing Texas Bylaws provide that any action required or permitted to be taken at any annual or special meeting of shareholders may be taken without a meeting, without prior notice and without a vote, if a consent in writing setting forth the action so taken is signed by the holders of outstanding stock having not less than the minimum number of votes that would be necessary to authorize or take such action at a meeting at which all shares entitled to vote thereon were present and voted and delivered to the Company.

If Proposal 2A is approved, stockholder action will be permitted only at a duly called meeting and action by written consent of stockholders will be prohibited.

If Proposal 2A is not approved, we will not include this provision in the Delaware Charter, and stockholders’ ability to act by written consent will be substantially the same under Delaware law as our current Texas Bylaw provision.

Reasons for the Proposed Provision

Our Board of Directors believes that this provision protects the interests of stockholders generally should a person or group holding a majority of our stock seek to call a special meeting of stockholders or seek stockholder action by written consent without a meeting, to the detriment of minority stockholders. By permitting action to be taken only at a duly called annual or special meeting of stockholders and eliminating action by written consent of stockholders, this provision in the Delaware Charter would give all of our stockholders entitled to vote on a particular matter advance notice of and the opportunity to participate in the determination of any proposed action and the ability to take judicial or other action to protect their interests.

This proposal could have a potential anti-takeover effect and might make it more difficult to effect or might discourage or delay a merger, tender offer, proxy contest or change in control and the removal of management, which stockholders might otherwise deem favorable. In particular, this proposal could have the effect of delaying or making more difficult transactions or other actions that do not have the support of our Board. This proposal is not being recommended in response to any currently pending or threatened attempt to acquire control of the Company.

PROPOSAL 2B

APPROVAL OF THE PROPOSED PROVISION IN THE DELAWARE CHARTER AND DELAWARE BYLAWS TO ELIMINATE THE ABILITY OF STOCKHOLDERS TO CALL A SPECIAL MEETING OF STOCKHOLDERS

Proposed Provision

Proposal 2B is a provision in the Delaware Charter and Delaware Bylaws to eliminate the ability of stockholders to call a special meeting of stockholders. If Proposal 2B is approved, the Delaware Charter and Delaware Bylaws will include the following provisions:

CHARTER: “Special meetings of the stockholders of the Corporation may be called only by the Chairman of the Board of Directors or the Chief Executive Officer of the Corporation or by a resolution adopted by the affirmative vote of a majority of the Board of Directors, and any power of stockholders to call a special meeting of stockholders is specifically denied.”

BYLAWS: “Special meetings of the stockholders may be called for any purpose or purposes, unless otherwise prescribed by statute or by the certificate of incorporation, by the Secretary only at the request of the Chairman of the Board, the Chief Executive Officer or by a resolution duly adopted by the affirmative vote of a majority of the Board of Directors. Such request shall state the purpose or purposes of the proposed meeting. Business transacted at any special meeting shall be limited to matters relating to the purpose or purposes stated in the notice of meeting.”

Delaware law provides that special meetings of the stockholders may be called by the board of directors or such other persons as are authorized in the certificate of incorporation or bylaws.

Our existing Texas Charter does not address this provision. Our existing Texas Bylaws provide that special meetings of shareholders may be called by the board of directors, the chairman of the board of directors, the president or an authorized committee of the board of directors at any time for any purpose or purposes. Special meetings of shareholders may also be called by the holders of at least 30% of all shares entitled to vote at the proposed special meeting.

If Proposal 2B is approved, stockholders holding at least 30% of all shares entitled to vote at a special meeting will no longer be able to call a special meeting of stockholders.

If Proposal 2B is not approved, we will revise the provision in the Delaware Charter and Delaware Bylaws to include that special meetings may also be called by holders of at least 30% of all shares entitled to vote at the proposed special meeting.

Reasons for the Proposed Provision

Our Board of Directors believes that this provision protects the interests of stockholders generally should a person or group holding a significant amount of our stock seek to call a special meeting of stockholders, to the detriment of other stockholders. By permitting action to be taken only at a special meeting of stockholders which has been duly called by our Secretary at the request of the Chairman of the Board, the Chief Executive Officer or by action of a majority of our Board of Directors, this provision in the Delaware Charter and Delaware Bylaws ensures that the Company and our Board of Directors have determined that the timing and purpose or purposes of any special meeting are appropriate and in the best interests of the Company and all of its stockholders.

This proposal could have a potential anti-takeover effect and might make it more difficult to effect or might discourage or delay a merger, tender offer, proxy contest or change in control and the removal of management, which stockholders might otherwise deem favorable. In particular, this proposal could have the effect of delaying or making more difficult transactions or other actions that do not have the support of our Board. This proposal is not being recommended in response to any currently pending or threatened attempt to acquire control of the Company.

PROPOSAL 2C

APPROVAL OF THE PROPOSED PROVISION IN THE DELAWARE CHARTER TO PROVIDE FOR

SUPERMAJORITY VOTING FOR CERTAIN AMENDMENTS TO THE CHARTER

Proposed Provision

Proposal 2C is a provision in the Delaware Charter to provide for supermajority voting in connection with future amendments to certain provisions of the Delaware Charter. If Proposal 2C is approved, the Delaware Charter will include the following provision:

“The affirmative vote of the holders of at least sixty-six and two-thirds percent (66-2/3%) of the voting power of the shares of the capital stock of the Corporation entitled to vote generally in the election of directors, voting together as a single class, shall be required to amend in any respect or repeal this Article IX, Paragraph A of Article V, or Articles VI, VII or VIII.”

Delaware law provides that amendments to the certificate of incorporation must be approved by the holders of a majority of the corporation’s stock entitled to vote thereon, unless the certificate of incorporation provides for a greater number.

Our existing Texas Charter provides that an amendment requires the approval of a majority of the outstanding shares, unless any class or series of shares is entitled to vote as a class thereon, in which event the vote of shareholders required for such action shall be the vote of a majority of the outstanding shares within each class or series of shares entitled to vote thereon as a class and at least a majority of the outstanding shares otherwise entitled to vote thereon. We have only common stock outstanding and no other class or series of shares.

If Proposal 2C is approved, the affirmative vote of holders of at least 66-2/3% of the shares of capital stock entitled to vote generally in the election of directors, voting together as a single class, will be required in connection with future amendments to certain provisions of our Delaware Charter as discussed further below.

If Proposal 2C is not approved, we will not include this provision in the Delaware Charter, and the required approval threshold to amend the Delaware Charter in the future will be substantially the same under Delaware law as our current Texas Charter provision.

Reasons for the Proposed Provision

Our Board of Directors believes that it is advisable to require the affirmative vote of at least 66-2/3% of the voting power of all then outstanding shares of capital stock entitled to vote generally in the election of directors for shareholders to amend, alter, repeal or adopt provisions inconsistent with, provisions in the Delaware Charter relating to:

Supermajority voting requirements are designed to provide protection for all stockholders by protecting them against self-interested action by one or a few large stockholders, and to encourage a person seeking control of a company to negotiate with its board of directors to reach terms that are fair and provide the best results for all stockholders. The Board has determined that it is appropriate to adopt supermajority voting requirements at this time with respect to the provisions of the Delaware Charter described above. In reaching these determinations,

the Board was cognizant of the substantial beneficial ownership of our common stock by members of our Board. The supermajority voting requirements ensure that minority stockholders have a voice in determining certain core features of our corporate structure and governance and major business combinations as well as the long-term continuity of our Board.

Supermajority voting requirements could render more difficult or discourage a merger, tender offer, proxy contest or other attempt to obtain control of the Company, and may have the effect of insulating the Board from action to remove directors when a majority of our shareholders believe doing so is in their best interest. The Board has not proposed the supermajority voting requirements described above with the intention of discouraging any such activity.

PROPOSAL 2D

APPROVAL OF THE PROPOSED PROVISION IN THE DELAWARE CHARTER TO PROVIDE FOR

SUPERMAJORITY VOTING FOR CERTAIN AMENDMENTS TO THE DELAWARE BYLAWS

Proposed Provision

Proposal 2D is a provision in the Delaware Charter to provide for supermajority voting in connection with future amendments to certain provisions of the Delaware Bylaws. If Proposal 2D is approved, the Delaware Charter will include the following provision:

“The Board of Directors is expressly authorized to adopt, amend or repeal the bylaws of the Corporation, without any action on the part of the stockholders, by the vote of at least a majority of the directors of the Corporation then in office. In addition to any vote of the holders of any class or series of stock of the Corporation required by law or the certificate of incorporation of the Corporation, the bylaws may also be adopted, amended or repealed by the affirmative vote of the holders of at least sixty-six and two-thirds percent (66-2/3%) of the voting power of the shares of the capital stock of the Corporation entitled to vote in the election of directors, voting as one class; provided, however, that the affirmative vote of the holders representing only a majority of the voting power of the shares of the capital stock of the Corporation entitled to vote in the election of directors, voting as one class, shall be required if such adoption, amendment or repeal of the bylaws has been previously approved by the affirmative vote of at least two-thirds (2/3) of the directors of the Corporation then in office.”

Delaware law provides that stockholders of a corporation entitled to vote have the right to amend, repeal or adopt the bylaws. If the corporation’s certificate of incorporation so provides, the corporation’s board of directors also has the have the right to amend, repeal or adopt the bylaws.

Our existing Texas Charter does not address this provision. Our existing Texas Bylaws provide that, subject to the Texas Charter, the Company’s shareholders or the board of directors may amend or repeal the bylaws, except that no amendment, modification or repeal of Article 10 (which pertains to indemnification) shall in any manner terminate, reduce or impair the right of any past, present or future individuals to be indemnified under the bylaws, nor the Company’s obligation to indemnify any such indemnitees, with respect to claims relating to matters occurring prior to such amendment, modification or repeal.

If Proposal 2D is approved, the affirmative vote of holders of at least 66-2/3% of the shares of capital stock entitled to vote in the election of directors, voting together as a single class, will be required in connection with future amendments to the Delaware Bylaws.

If Proposal 2D is not approved, we will not include this provision in the Delaware Charter, and the required approval threshold to amend the Delaware Bylaws in the future will be substantially the same under Delaware law as our current Texas Bylaws provision.

Reasons for the Proposed Provision

Our Board of Directors believes that it is advisable to require the affirmative vote of at least 66-2/3% of the voting power of all then outstanding shares of capital stock entitled to vote in the election of directors for shareholders to adopt, amend or repeal the Delaware Bylaws.

Supermajority voting requirements are designed to provide protection for all stockholders by protecting them against self-interested action by one or a few large stockholders, and to encourage a person seeking control of a company to negotiate with its board of directors to reach terms that are fair and provide the best results for all stockholders. The Board believes that it is appropriate to adopt supermajority voting requirements with respect to the Delaware Bylaws as described above. In reaching this determination, the Board was cognizant of the substantial beneficial ownership of our common stock by members of our Board. The supermajority voting

requirements ensure that minority stockholders have a voice in determining certain features of the Company’s corporate structure and governance and major business combinations as well as the long-term continuity of our Board.

Supermajority voting requirements could render more difficult or discourage a merger, tender offer, proxy contest or other attempt to obtain control of the Company, and may have the effect of insulating the Board from action to remove directors when a majority of our shareholders believe doing so is in their best interest. The Board has not proposed the supermajority voting requirements described above with the intention of discouraging any such activity.

PROPOSAL 2E

APPROVAL OF THE PROPOSED PROVISION IN THE DELAWARE CHARTER TO PROVIDE THAT THE COURT OF CHANCERY OF THE STATE OF DELAWARE WILL BE THE EXCLUSIVE FORUM FOR CERTAIN LEGAL ACTIONS

Proposed Provision

Proposal 2E is a provision in the Delaware Charter to provide that, unless the Company consents in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware will be the exclusive forum for certain legal actions. If Proposal 2E is approved, the Delaware Charter will include the following provision:

“Unless the Corporation consents in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware shall be the sole and exclusive forum for (i) any derivative action or proceeding brought on behalf of the Corporation, (ii) any action asserting a claim of breach of a fiduciary duty owed by any director, officer or other employee of the Corporation to the Corporation or the Corporation’s stockholders, (iii) any action asserting a claim arising pursuant to any provision of the DGCL, or (iv) any action asserting a claim governed by the internal affairs doctrine. Any person or entity purchasing or otherwise acquiring any interest in shares of capital stock of the Corporation shall be deemed to have notice of and consented to the provisions of this Article VII, Paragraph D.”

Section 115 of Delaware law expressly permits a corporation’s certificate of incorporation or bylaws to require that any or all “internal corporate claims” be brought solely and exclusively in any or all Delaware courts, and that no provision of a corporation’s certificate of incorporation or bylaws may prohibit bringing such claims in Delaware courts.

Neither our existing Texas Charter nor the Texas Bylaws contain a forum selection provision.

If Proposal 2E is approved, the Court of Chancery of the State of Delaware will be the exclusive forum for certain legal actions, unless the Company consents in writing otherwise.

If Proposal 2E is not approved, we will not include this provision in the Delaware Charter, and there will be no limitation on the ability of stockholders to bring an action in any appropriate forum.

Reasons for the Proposed Provision

Our Board of Directors believes that our stockholders will benefit from having certain disputes litigated in the Court of Chancery of the State of Delaware. Some plaintiffs might prefer to litigate matters in a forum outside of Delaware because another court may be more convenient for, or viewed as being more favorable to them. This exclusive forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that the stockholder finds favorable for disputes with us or our directors, officers or other employees and may discourage lawsuits with respect to such claims. However, the Board believes that the benefits to the Company and its stockholders outweigh these concerns. Delaware offers a system of specialized courts to deal with corporate law questions, with streamlined procedures and processes which help provide relatively quick decisions. These courts have developed considerable expertise in dealing with corporate law issues, as well as a substantial and influential body of case law construing Delaware’s corporate law and long-standing precedent regarding corporate governance. In addition, the adoption of this provision would reduce the risk that the Company could be involved in duplicative litigation in more than one forum, as well as the risk that the outcome of cases in multiple forums could be inconsistent, even though each forum purports to follow Delaware law.

This provisions still gives the Board the flexibility to consent to an alternative forum in instances when the Board deems it appropriate.

PROPOSAL 3

APPROVAL OF THE REINCORPORATION

Our Board has unanimously approved and recommends that our shareholders approve the reincorporation of the Company from the State of Texas to the State of Delaware (the “Reincorporation”). The Board believes that the Reincorporation will result in the advantages described below. In this Proposal 3, we sometimes refer to the Company before and after the Reincorporation as “Acer Texas” and “Acer Delaware,” respectively.

Summary

The principal effects of the Reincorporation will be as follows:

Certificates representing shares of our common stock will continue to represent an equal number of shares of Acer Delaware common stock. The Reincorporation will not affect the validity of the currently outstanding stock certificates. Consequently, it will not be necessary for our shareholders to exchange their existing stock certificates for stock certificates of Acer Delaware. Shares of our common stock that are freely tradeable prior to the Reincorporation will continue to be freely tradeable as shares of Acer Delaware common stock, and shares of our common stock that are subject to restrictions prior to the Reincorporation will continue to be subject to the same restrictions as shares of Acer Delaware common stock. The Reincorporation will not change the respective positions of the Company or our shareholders under federal securities laws. The registration statements of the Company on file with the SEC immediately prior to the Reincorporation will not be affected. Our common stock is listed for trading on the Nasdaq Capital Market under the ticker symbol “ACER.” After the Reincorporation, our common stock will be traded on the Nasdaq Capital Market, without interruption, under the same symbol and with the same CUSIP number.

The Reincorporation will not result in any material change in our business, assets or financial position or in the persons who constitute our Board, including those persons who are elected at the Annual Meeting. The individuals serving as officers of Acer Texas immediately before the Reincorporation will continue to serve as officers of Acer Delaware after the Reincorporation. The consolidated financial condition and results of operations of Acer Delaware immediately after consummation of the Reincorporation will be the same as those of the Acer Texas immediately before the consummation of the Reincorporation. We believe that the Reincorporation will not affect any of our material contracts with any third parties, and that our rights and

obligations under such material contractual arrangements will continue as rights and obligations of Acer Delaware. Upon consummation of the Reincorporation, our principal executive offices will continue to be located at One Gateway Center, Suite 351 (300 Washington St.), Newton, Massachusetts 02458.

Plan of Conversion

To accomplish the Reincorporation, the Board has adopted a plan of conversion (the “Plan of Conversion”) in substantially the form ofAppendix Ato this Proxy Statement. The Plan of Conversion provides that we will convert into a Delaware corporation and will thereafter be subject to all of the provisions of the General Corporation Law of the State of Delaware (the “DGCL”).

Assuming that our shareholders approve this Proposal 3, we will cause the Reincorporation to be effected as soon as practicable thereafter by filing with the Secretary of State of the State of Texas a certificate of conversion substantially in the form ofAppendix B to this Proxy Statement (the “Texas Certificate of Conversion”) and by filing with the Secretary of State of the State of Delaware (i) a certificate of conversion substantially in the form ofAppendix C to this Proxy Statement (the “Delaware Certificate of Conversion”) and (ii) the Delaware Charter, which will govern Acer Delaware as a Delaware corporation, substantially in the form ofAppendix D to this Proxy Statement. In addition, assuming that our shareholders approve this Proposal 3, the Board will adopt the Delaware Bylaws for Acer Delaware substantially in the form ofAppendix E to this Proxy Statement, and we will enter into a new indemnification agreement with each director and officer of Acer Delaware based upon provisions of the DGCL, substantially in the form ofAppendix F to this Proxy Statement (the “Delaware Indemnification Agreement”).

Concurrently with effecting the Reincorporation, we also intend to eliminate our current holding company structure as described below under “Subsidiary Merger to Eliminate Holding Company Structure.” Because our wholly owned subsidiary Private Acer is currently a Delaware corporation, and only one entity may be incorporated at a particular time with that name, the initial Delaware Charter for Acer Delaware will use a placeholder name of “Acer Reincorporation, Inc.” Implementing the subsidiary merger of Private Acer with and into Acer Delaware will allow the name of “Acer Therapeutics Inc.” to become available in Delaware and, as part of the subsidiary merger, Acer Delaware will change its name from “Acer Reincorporation, Inc.” to “Acer Therapeutics Inc.”

All descriptions of the Plan of Conversion, the Texas Certificate of Conversion, the Delaware Certificate of Conversion, the Delaware Charter, the Delaware Bylaws and the Delaware Indemnification Agreement are qualified by and subject to the more complete information set forth in those documents. Copies of the existing Texas Charter and the existing Texas Bylaws are filed with the U.S. Securities and Exchange Commission (the “SEC”) as exhibits to our periodic reports and also are available for inspection at our principal executive offices. Copies will be sent to shareholders free of charge upon request by writing us at Acer Investor Relations, One Gateway Center, Suite 351 (300 Washington St.), Newton, MA 02458, or by calling us at (844)902-6100.

Notwithstanding the foregoing, the Reincorporation may be delayed by the Board or the Plan of Conversion may be terminated and abandoned by action of the Board any time before the effective date (whether before or after shareholder approval), if the Board determines for any reason that such delay or termination would be in the best interests of the Company and our shareholders. If the Reincorporation is approved by our shareholders, the Reincorporation would become effective upon the filing (and acceptance thereof by the Secretary of State of the State of Texas and the Secretary of State of the State of Delaware, as applicable) of the Texas Certificate of Conversion, the Delaware Certificate of Conversion and the Delaware Charter.

Consequences of Shareholder Vote

Approval of this Proposal 3 by our shareholders will constitute approval of the Reincorporation, the Plan of Conversion, the Texas Certificate of Conversion, the Delaware Certificate of Conversion, the Delaware Charter,

the Delaware Bylaws and the Delaware Indemnification Agreement, except in any circumstance where Proposal 2A, 2B, 2C, 2D or 2E is not approved. If this Proposal 3 is approved and implemented, the provisions of the Delaware Charter and Delaware Bylaws will depend upon whether any or all of Proposals 2A, 2B, 2C, 2D and 2E are approved. If a proposal to include a certain provision is approved, the Delaware Charter and Delaware Bylaws will include a provision substantively as described in Proposal 2A, 2B, 2C, 2D or 2E. If a proposal to include a certain provision is not approved, Proposals 2A, 2B, 2C, 2D and 2E describe the impact on the Delaware Charter and Delaware Bylaws, as applicable.

If Proposal 3 fails to obtain the requisite vote for approval, the Reincorporation will not be consummated and the Company will continue to be incorporated in the State of Texas and governed by the Texas Charter and the Texas Bylaws, and the Company will not enter into the Delaware Indemnification Agreements with our directors and officers.

Certain Risks Associated with the Reincorporation

Notwithstanding the belief of our Board as to the benefits to our shareholders of the Reincorporation, there can be no assurance that the Reincorporation will result in the benefits discussed in this Proxy Statement, including the benefits of or resulting from access to Delaware courts, incorporation under Delaware law, the ability to attract and retain qualified directors and officers or certain changes in our corporate governance. In addition, the Delaware Charter and the Delaware Bylaws, in comparison to the Texas Charter and the Texas Bylaws, will contain or eliminate certain provisions that may have the effect of reducing certain rights of our shareholders. See the section entitled “Comparison of Shareholder Rights Before and After the Reincorporation” for more details.

Reasons for the Reincorporation

The State of Delaware has been a leading jurisdiction in adopting a comprehensive and coherent set of corporate laws that are responsive to the evolving legal and business needs of corporations organized under Delaware law. Our Board believes that it is important for the Company to be able to draw upon well-established principles of corporate governance in making legal and business decisions. The prominence and predictability of Delaware corporate law provide a reliable foundation on which our governance decisions can be based, and we believe that our shareholders will benefit from the responsiveness of Delaware corporate law to their needs. In addition, the Board believes that direct benefits that Delaware law provides to a corporation indirectly benefit our shareholders, who are our owners. Specifically, our Board believes that there are several benefits of the Reincorporation, as summarized below.

Access to Specialized Courts

Delaware has a specialized court of equity called the Court of Chancery that hears corporate law cases. The Delaware Court of Chancery operates under rules that are intended to ensure litigation of disputes in a timely and effective way, keeping in mind the timelines and constraints of business decision-making and market dynamics. The appellate process on decisions emanating from the Court of Chancery is similarly streamlined, and the justices of Delaware appellate courts tend to have substantial experience with corporate cases because of the relatively higher volume of these cases in the Delaware courts. As the leading state of incorporation for both private and public companies, Delaware has developed a vast body of corporate law that helps to promote greater consistency and predictability in judicial rulings. In contrast, Texas does not have a similar specialized court established to hear corporate law cases. Rather, disputes involving questions of Texas corporate law are either heard in law courts of general jurisdiction, alongside other civil cases, or, if federal jurisdiction exists, a federal district court. These courts hear many different types of cases, and the cases may be heard before judges or juries with limited corporate law experience. As a result, corporate law cases brought in Texas may not proceed as expeditiously as cases brought in Delaware and the outcomes in such courts may be less consistent and predictable.

Highly Developed and Predictable Corporate Law

Delaware has one of the most modern statutory corporation codes, which is revised regularly in response to changing legal and business needs of corporations. The Delaware legislature is particularly responsive to developments in modern corporate law and Delaware has proven sensitive to changing needs of corporations and their shareholders. The Delaware Secretary of State is viewed as particularly flexible and responsive in its administration of the filings required for mergers, acquisitions and other corporate transactions. Delaware has become a preferred domicile for most major American corporations and the DGCL and administrative practices have become comparatively well-known and widely understood. As a result of these factors, it is anticipated that the DGCL will provide greater efficiency, predictability and flexibility in the Company’s legal affairs than is presently available under Texas law. In addition, Delaware case law provides a well-developed body of law defining the proper duties and decision making processes expected of boards of directors in evaluating potential or proposed extraordinary corporate transactions.

Enhanced Ability to Attract and Retain Directors and Officers

The Board believes that the Reincorporation will enhance our ability to attract and retain qualified directors and officers, as well as encourage directors and officers to continue to make independent decisions in good faith on behalf of the Company. We are in a competitive industry and compete for talented individuals to serve on our management team and on our Board. The vast majority of public companies are incorporated in Delaware. Not only is Delaware law more familiar to directors, it also offers greater certainty and stability from the perspective of those who serve as corporate officers and directors. The parameters of director and officer liability are more extensively addressed in Delaware court decisions and are therefore better defined and better understood than under Texas law. The Board believes that the Reincorporation will enhance our ability to recruit and retain directors and officers. We believe that the better understood and comparatively stable corporate environment afforded by Delaware law will enable us to compete more effectively with other public companies in the recruitment of talented and experienced directors and officers.

For a discussion of certain differences in shareholder rights and the powers of management under Delaware and Texas law, see the section entitled “Comparison of Shareholder Rights Before and After the Reincorporation” below.

Comparison of Shareholder Rights Before and After the Reincorporation

Because of differences between the Texas Business Organizations Code (“TBOC”) and the DGCL, as well as differences between the Company’s charter documents before and after the Reincorporation, the Reincorporation will effect some changes in the rights of the Company’s shareholders. Summarized below are the most significant differences between the rights of the shareholders of the Company before and after the Reincorporation as a result of the differences between each of the TBOC and the DGCL, the Texas Charter and the Texas Bylaws, and the Delaware Charter and the Delaware Bylaws. The summary below is not intended to be relied upon as an exhaustive list of all the differences or a complete description of the differences, and is qualified in its entirety by reference to the Delaware Charter and the Delaware Bylaws. The provisions of the Delaware Charter and Delaware Bylaws will depend in part upon whether any or all of Proposals 2A, 2B, 2C, 2D and 2E are approved, as discussed above in those proposals.

Business Combination Statute

Texas

The TBOC prohibits specific mergers, sales of assets, reclassifications and other transactions between a Texas public corporation and an “affiliated shareholder” for a period of three years after the date the shareholder obtained “affiliated shareholder” status. “Affiliated shareholder” is defined as a person who beneficially owns— or has owned within the preceding three-year period—20% or more of the outstanding stock of a Texas public

corporation for a period of three years following the shareholder acquiring shares representing 20% or more of the corporation’s voting power. The TBOC provides an exception to this prohibition if: (i) the board of directors of the corporation approves the transaction or the acquisition of shares by the affiliated shareholder prior to the affiliated shareholder becoming an affiliated shareholder,(ii) two-thirds—or such higher threshold as specified in the certificate of formation—of the unaffiliated shareholders approve the transaction at a meeting held no earlier than six months after the shareholder acquires such ownership, or (iii) the affiliated shareholder was an affiliated shareholder before December 31, 1996, and continued as such through the date of the transaction.

The Texas Charter does not alter the Texas business combinations statute.

Delaware

The DGCL prohibits certain transactions between a Delaware corporation and an “interested stockholder” for a period of three years after the date the interested stockholder acquired its stock. “Interested stockholder” is broadly defined as a person (including the affiliates and associates of such person) that is directly or indirectly a beneficial owner of 15% or more of the outstanding voting stock of a Delaware corporation. Prohibited transactions include: (i) mergers, (ii) consolidations, (iii) sales or other dispositions of assets having an aggregate market value of 10% or more of either the consolidated assets or the outstanding stock of a company, and (iv) certain transactions that would result in the issuance or transfer of stock of a company, increase the interested stockholder’s proportionate share of ownership in a company, or grant the interested stockholder disproportionate financial benefits. The DGCL provides an exception to this prohibition if: (i) the business combination or the transaction in which the stockholder became an interested stockholder is approved by that company’s board of directors prior to the date the interested stockholder became an interested stockholder, (ii) the interested stockholder acquired at least 85% of the voting stock of that company in the transaction in which it became an interested stockholder, or (iii) the business combination is approved by a majority of the board of directors and the affirmative vote oftwo-thirds of the votes entitled to be cast by disinterested stockholders at an annual or special meeting (and not by written consent).

The Delaware Charter will not alter the Delaware business combinations statute.

Comparison

Under the DGCL, shareholders owning 15% of the voting stock of a company (or in certain cases an even smaller percentage) might be able to block certain transactions which is a smaller percentage than is currently the case under Texas law. The application of either statute could make more difficult or discourage a tender offer or the completion of a “second step” merger by a holder of a substantial block of a company’s voting stock, irrespective of whether such action might be perceived by shareholders holding a majority of the voting stock to be beneficial to a company and its shareholders.

The application of the DGCL could adversely affect the ability of shareholders to benefit from certain transactions which are opposed by the board or by shareholders owning 15% of the voting stock of a company, even if the price offered in those transactions represents a premium over the then-current market price of a company’s voting stock, to the extent that a market for that stock then exists. To the extent that a board’s disapproval of a proposed transaction discourages establishment of a controlling stock interest, the position of such board and the company’s management may be strengthened, thereby assisting those persons in retaining their positions.

Nevertheless, the Board believes that, on balance, becoming subject to the provisions of the DGCL will be in the best interest of the Company and its shareholders. In recent years there have been a number of surprise take-overs of publicly-owned corporations. These transactions have occurred through tender offers or other sudden purchases of a substantial number of outstanding shares. Frequently, these tender offers and other share purchases have been followed by a merger or other form of complete acquisition of the target company by the

purchaser without any negotiations with the target company’s board of directors. Such a “second step” business combination automatically eliminates minority interests in the target company, often for less valuable consideration per share than was paid in the purchaser’s original tender offer or market purchases. In other instances, a purchaser has used its controlling interest to effect other transactions having an adverse impact on the target company and its shareholders.

Sales, Leases, Exchanges or Other Dispositions

Texas

Generally, the sale, lease, exchange or other disposition of all, or substantially all, of the property and assets of a Texas corporation requires the approval of the holders of at leasttwo-thirds of the outstanding shares of the corporation entitled to vote. No such approval is required, however, if the transaction is made in the usual and regular course of the corporation’s business. Under Texas law, the transfer of substantially all of a corporation’s assets in such a manner that the corporation continues directly or indirectly to engage in one or more businesses is deemed to be in the usual and regular course of its business.

The Texas Charter contains a provision setting the approval threshold at a majority of the outstanding shares, unless any class or series of shares is entitled to vote as a class thereon, in which event the vote of shareholders required for such action shall be the vote of a majority of the outstanding shares within each class or series of shares entitled to vote thereon as a class and at least a majority of the outstanding shares otherwise entitled to vote thereon.

Delaware

A Delaware corporation may sell, lease or exchange all or substantially all of its property and assets when and as authorized by a majority of the outstanding stock of the corporation entitled to vote thereon, unless the certificate of incorporation provides to the contrary.

The Delaware Charter will not address this issue.

Approval of Mergers

Texas

Under Texas law, any merger with a third party requires approval bytwo-thirds of the outstanding shares of the Texas corporation unless a different threshold, not less than a majority, is specified in the certificate of formation.

The Texas Charter contains a provision setting the approval threshold at a majority of the outstanding shares, unless any class or series of shares is entitled to vote as a class thereon, in which event the vote of shareholders required for such action shall be the vote of a majority of the outstanding shares within each class or series of shares entitled to vote thereon as a class and at least a majority of the outstanding shares otherwise entitled to vote thereon.

Delaware

Under Delaware law, any merger with a third party must be approved by a majority of the stockholders.

The Delaware Charter will not address this issue.

Appraisal Rights

Texas

Except for the limited classes of mergers, consolidations, sales and asset dispositions for which no shareholder approval is required under Texas law, shareholders of Texas corporations with voting rights have dissenters’ rights in the event of a merger, consolidation, conversion, sale, lease, exchange or other disposition of all, or substantially all, the property and assets of the corporation. However, a shareholder of a Texas corporation has no dissenters’ rights with respect to any plan or merger or conversion in which there is a single surviving or new domestic or foreign corporation, or with respect to any plan of exchange, if:

(1) the ownership interest, or a depository receipt in respect of the ownership interest, held by the owner is part of a class or series of ownership interests, or depository receipts in respect of ownership interests, that are, on the record date set for purposes of determining which owners are entitled to vote on the plan of merger, conversion, or exchange, as appropriate:

(A) listed on a national securities exchange (the Company currently meets this condition by virtue of its listing on the Nasdaq Capital Market); or

(B) held of record by at least 2,000 owners;

(2) the owner is not required by the terms of the plan of merger, conversion, or exchange, as appropriate, to accept for the owner’s ownership interest any consideration that is different from the consideration to be provided to any other holder of an ownership interest of the same class or series as the ownership interest held by the owner, other than cash instead of fractional shares or interests the owner would otherwise be entitled to receive; and

(3) the owner is not required by the terms of the plan of merger, conversion, or exchange, as appropriate, to accept for the owner’s ownership interest any consideration other than:

(A) ownership interests, or depository receipts in respect of ownership interests, of a another entity of the same general organizational type that, immediately after the effective date of the merger, conversion, or exchange, as appropriate, will be part of a class or series of ownership interests, or depository receipts in respect of ownership interests, that are:

(i) listed on a national securities exchange or authorized for listing on the exchange on official notice of issuance;

(ii) held of record by at least 2,000 owners;

(B) cash instead of fractional ownership interests the owner would otherwise be entitled to receive; or

(C) any combination of the ownership interests and cash above.

Delaware

Under Delaware law, stockholders have no appraisal rights in the event of a merger or consolidation of the corporation if the stock of the Delaware corporation is listed on a national securities exchange (the Company currently meets this condition by virtue of its listing on the Nasdaq Capital Market) or if such stock is held of record by more than 2,000 stockholders. Stockholders of a Delaware parent corporation have no appraisal rights in a merger between that parent corporation and a subsidiary corporation wholly owned by that parent corporation. Even if appraisal rights would not otherwise be available under Delaware law in the cases described above, stockholders would still have appraisal rights if they are required by the terms of the agreement of merger and consolidation to accept for their stock anything other than:

(1) shares of stock:

(A) of the surviving corporation; or

(B) of any other corporation whose shares at the effective date of the merger or consolidation will be either listed on a national securities exchange or held of record by more than 2,000 stockholders;

(2) cash in lieu of fractional shares; or

(3) a combination of such shares and such cash.

Otherwise, stockholders of a Delaware corporation have appraisal rights in consolidations and mergers.

Under Delaware law, any corporation may provide in its certificate of incorporation that appraisal rights will also be available as a result of an amendment to its certificate of incorporation, any merger or consolidation involving such corporation, or the sale of all or substantially all of the assets of the corporation.

The Delaware Charter will have no such provisions.

Shareholder Consent to Action Without a Meeting

Texas

Under Texas law, any action that may be taken at a meeting of the shareholders may be taken without a meeting if written consent thereto is signed by all the holders of shares entitled to vote on that action. The certificate of formation of a Texas corporation may provide that action by written consent in lieu of a meeting may be taken by the holders of that number of votes which would be required to take the action which is the subject of the consent at a meeting at which each of the shares entitled to vote thereon were present and voted.

The Texas Bylaws provide that any action required or permitted to be taken at any annual or special meeting of shareholders may be taken without a meeting, without prior notice and without a vote, if a consent in writing setting forth the action so taken is signed by the holders of outstanding stock having not less than the minimum number of votes that would be necessary to authorize or take such action at a meeting at which all shares entitled to vote thereon were present and voted and delivered to the Company.

Delaware

Under Delaware law, unless otherwise provided in the certificate of incorporation, any action that can be taken at a meeting of the stockholders can be taken without such meeting if written consent thereto is signed by the holders of outstanding stock having the minimum number of votes necessary to authorize or take such action at a meeting at which all shares entitled to vote thereon were presented and voted.

Subject to shareholder approval of Proposal 2A, our Board of Directors has proposed that the Delaware Charter will provide that no action required or permitted to be taken at any annual or special meeting of the stockholders may be taken without a meeting and the power of stockholders to consent in writing, without a meeting, to the taking of any action will be specifically denied.

Procedures for Filling Vacant Directorships

Texas

Under Texas law, any vacancy occurring in the board of directors may, unless otherwise authorized by a corporation’s certificate of formation, be filled only: (i) by the affirmative vote of the majority of the directors then in office, (ii) by the sole remaining director, or (iii) by the affirmative vote of the shareholders. A directorship to be filled because of an increase in the number of directors may be filled by the shareholders or by the board of directors for a term of office continuing only until the next election of one or more directors by the shareholders. The board of directors may not fill more than two such directorships during the period between any two successive annual meetings of shareholders.

The Texas Bylaws provide that any vacancy on the board of directors may be filled by a majority of the remaining directors, although less than a quorum, or by a sole remaining director.

Delaware

Under Delaware law, unless the certificate of incorporation or bylaws provide otherwise, vacancies and newly created directorships resulting from any increase in the authorized number of directors may be filled by a majority of the directors then in office, although less than a quorum, or by a sole remaining director.

The Delaware Bylaws will provide that any vacancy on the board of directors may be filled by a majority of the remaining directors, although less than a quorum, or by a sole remaining director, and that if there are no directors in office, then an election of directors may be held in the manner provided by statute.

Right to Call Meetings

Texas

Under Texas law, shareholders are guaranteed the right to call special meetings. Unless otherwise specified in the corporation’s certificate of formation, holders of not less than 10% of all of the shares entitled to vote at the proposed meeting have the right to call a special shareholders’ meeting. The certificate of formation may allow for special meetings to be called by a number of shares greater than or less than 10%, but it may not set the required number of shares above 50%. The president, board of directors, or any other person authorized to call special meetings by the certificate of formation or bylaws of the corporation may also call special shareholders’ meetings.

The Texas Bylaws provide that special meetings of shareholders may be called by the board of directors, the chairman of the board of directors, the president or an authorized committee of the board of directors at any time for any purpose or purposes. Special meetings of shareholders may also be called by the holders of at least 30% of all shares entitled to vote at the proposed special meeting.

Delaware

Delaware law provides that special meetings of the stockholders may be called by the board of directors or such other persons as are authorized in the certificate of incorporation or bylaws.

Subject to shareholder approval of Proposal 2B, our Board of Directors has proposed that the Delaware Charter and the Delaware Bylaws will provide that special meetings of the stockholders may be called by Acer Delaware’s secretary only at the request of the chairman of the board of directors, the Chief Executive Officer or by a resolution duly adopted by the affirmative vote of a majority of the board of directors, and any power of stockholders to call a special meeting of stockholders will be specifically denied.

Voting by Proxy

Texas

Under Texas law, a shareholder may authorize another person or persons to act for such shareholder by proxy. A proxy is only valid for eleven months from its date unless otherwise provided in the proxy.

Delaware

Under Delaware law, a stockholder may authorize another person or persons to act for such stockholder by proxy. A proxy is valid for three years from its date unless otherwise provided in the proxy.

Charter Amendments

Texas

Under Texas law, an amendment to the certificate of formation requires the approval of the holders of at leasttwo-thirds of the outstanding shares of the corporation, unless a different threshold, not less than a majority, is specified in the certificate of formation.

The Texas Charter contains a provision setting the approval threshold at a majority of the outstanding shares, unless any class or series of shares is entitled to vote as a class thereon, in which event the vote of shareholders required for such action shall be the vote of a majority of the outstanding shares within each class or series of shares entitled to vote thereon as a class and at least a majority of the outstanding shares otherwise entitled to vote thereon.

Delaware

Delaware law provides that amendments to the certificate of incorporation must be approved by the holders of a majority of the corporation’s stock entitled to vote thereon, unless the certificate of incorporation provides for a greater number.

Subject to shareholder approval of Proposal 2C, our Board of Directors has proposed that the Delaware Charter will require that the approval of the holders of at leasttwo-thirds of the outstanding shares of Acer Delaware then entitled to vote in an election of directors, voting as a single class, shall be required to amend in any respect or repeal Article IX (which pertains to amendments to the Delaware Charter), Paragraph A of Article V (which pertains to amendments to the Delaware Bylaws), or Articles VI (which pertains to elections of directors and filling vacancies on the board of directors), VII (which pertains to actions by written consent, calling of special meetings, shareholder nominations and forum selection) or VIII (which pertains to limitation of liability, indemnification and insurance).

Bylaw Amendments

Texas

Generally, under Texas law, the board of directors may amend, repeal or adopt a corporation’s bylaws. However, a corporation’s certificate of formation may reserve this power exclusively to a majority of the shareholders. Similarly, the shareholders, in amending, repealing or adopting a particular bylaw, may expressly provide that the board of directors may not amend, readopt or repeal that bylaw. Texas case law permits the corporation to increase the required threshold of shareholders necessary to amend the bylaws.

The Texas Bylaws provide that, subject to the Texas Charter, the Company’s shareholders or the board of directors may amend or repeal the bylaws, except that no amendment, modification or repeal of Article 10 (which pertains to indemnification) shall in any manner terminate, reduce or impair the right of any past, present or future individuals to be indemnified under the bylaws, nor the Company’s obligation to indemnify any such indemnitees, with respect to claims relating to matters occurring prior to such amendment, modification or repeal.

Delaware

Under Delaware law, stockholders of a corporation entitled to vote have the right to amend, repeal or adopt the bylaws. If the corporation’s certificate of incorporation so provides, the corporation’s board of directors also has the have the right to amend, repeal or adopt the bylaws.

Our Board of Directors has proposed that the Delaware Charter and Delaware Bylaws will provide that the board of directors is expressly authorized to adopt, amend or repeal the Delaware Bylaws, without any action on

the part of the stockholders, by the vote of at least a majority of the directors then in office. Subject to shareholder approval of Proposal 2D, our Board of Directors has also proposed that the Delaware Charter will provide that, in addition to any vote of the holders of any class or series of stock required by law or the Delaware Charter, the Delaware Bylaws may also be adopted, amended or repealed by the affirmative vote of the holders of at leasttwo-thirds of the voting power of the shares of the capital stock entitled to vote in the election of directors, voting as one class; provided, however, that the affirmative vote of the holders representing only a majority of the voting power of the shares of the capital stock entitled to vote in the election of directors, voting as one class, shall be required if such adoption, amendment or repeal of the bylaws has been previously approved by the affirmative vote of at leasttwo-thirds of the directors then in office.

Classified Board of Directors

Under both Texas law and under Delaware law, corporations may provide for classified or staggered boards.

Neither of the Texas Charter or the Texas Bylaws provide for a classified board of directors. Neither of the Delaware Charter or the Delaware Bylaws will provide for a classified board of directors.

Removal of Directors

Texas

Under Texas law, subject to the exceptions discussed below or as otherwise provided by the certificate of formation or bylaws of a corporation, the shareholders may remove a director, with or without cause, by a vote of the holders of a majority of the shares entitled to vote at an election of the directors. If the corporation’s directors serve staggered terms, a director may not be removed except for cause unless the certificate of formation provides otherwise. If the certificate of formation permits cumulative voting and less than the entire board is to be removed, a director may not be removed if the votes cast against the removal would be sufficient to elect him or her if cumulatively voted at an election of the entire board of directors. Where a corporation’s certificate of formation provides that separate classes or series of stockholders are entitled, as such a class or series, to elect separate directors, in calculating the sufficiency of votes for removal of such a director, only the votes of the holders of such a class or series are considered.

The Texas Bylaws provide that shareholders holding a majority of the outstanding shares entitled to vote in the election of directors may remove any director or the entire board of directors at any time, with our without cause. The Texas Charter provides that the shareholders shall not have cumulative voting rights.

Delaware

Under Delaware law, subject to the exceptions discussed below, a majority of stockholders then entitled to vote at an election of directors may remove a director with or without cause. If the board of directors of a Delaware corporation is classified (i.e., elected for staggered terms), a director may only be removed for cause, unless the corporation’s certificate of incorporation provides otherwise. If a corporation uses cumulative voting and less than the entire board is to be removed, no director may be removed without cause if the votes cast against his or her removal would be sufficient to elect him or her if then cumulatively voted at an election of the entire board of directors. Where a corporation’s certificate of incorporation provides that separate classes or series of stockholders are entitled, as such a class or series, to elect separate directors, in calculating the sufficiency of votes for removal of such a director, only the votes of the holders of such a class or series are considered.

The Delaware Bylaws will provide that any director or the entire board of directors may be removed, with or without cause, by the holders of a majority of the voting power of the capital stock issued and outstanding then entitled to vote at an election of directors. Neither of the Delaware Charter or the Delaware Bylaws will grant cumulative voting rights in the election of directors.

Shareholder Nominations and Proposals

Texas

The Texas Bylaws provide that in order for a shareholder to make any director nomination or propose any other action at an annual meeting of shareholders, the shareholder must provide notice in writing to the Company’s secretary, which must be delivered to or mailed and received not less than 50 days nor more than 90 days prior to the date of such meeting, provided that in the event that less than 75 days’ notice of the date of the meeting is given to the Company’s shareholders, notice must be received no later than the 15th day following the date on which the Company’s notice of the date of the meeting was mailed.

Delaware

The Delaware Bylaws will provide that in order for a stockholder to make any director nomination or propose any other action at an annual meeting of stockholders, the stockholder must provide notice in writing to Acer Delaware’s secretary not earlier than the close of business on the 120th day and not later than the close of business on the 90th day prior to the first anniversary of the date of Acer Delaware’s proxy statement provided in connection with the preceding year’s annual meeting; provided, however, that in the event that no annual meeting was held in the previous year or the date of the annual meeting is more than 30 days before or after the first anniversary of the preceding year’s annual meeting, notice by the stockholder must be received by the secretary of Acer Delaware not later than the close of business on the later of the 90th day prior to such annual meeting and the tenth 10th day following the day on which public announcement of the date of such meeting is first made. Our Board of Directors believes these timeframes are more appropriate for a public company and will enhance the Company’s ability to respond to stockholder nominations or proposals.

Proxy Access

Texas

The Texas Bylaws do not contain a proxy access provision requiring minimum ownership requirements for shareholder director nominations.

Delaware

The Delaware Bylaws will not contain a proxy access provision requiring minimum ownership requirements for shareholder director nominations.

Number of Directors

Texas

The Texas Charter and the Texas Bylaws provide that the board of directors will consist of not less than two nor more than ten members, as the board of directors may determine by resolution from time to time.

Delaware

The Delaware Bylaws will provide that the number of directors shall be fixed from time to time by resolution adopted by a majority of the directors then in office.

Inspection of Books and Records

Texas

Under Texas law, a shareholder may, upon written demand stating a proper purpose, inspect the books and records of a corporation if such shareholder holds at least 5% of the outstanding shares of stock of the corporation or has been a holder of shares for at least six months prior to such demand.

Delaware

Under Delaware law, any stockholder may inspect the corporation’s books and records upon written demand under oath stating the purpose of the inspection. If the corporation refuses to permit inspection or does not reply to the demand within five business days after the demand has been made, the stockholder may apply to the Court of Chancery for an order to compel such inspection.

Distributions and Dividends

Texas

Under Texas law, a distribution is defined as a transfer of cash or other property (except a corporation’s own shares or rights to acquire its shares), or an issuance of debt, by a corporation to its shareholders in the form of: (i) a dividend on any class or series of the corporation’s outstanding shares, (ii) a purchase or redemption, directly or indirectly, of its shares, or (iii) a payment in liquidation of all or a portion of its assets. Under Texas law, a corporation may not make a distribution if such distribution violates its certificate of formation or, unless the corporation is in receivership, if it either renders the corporation unable to pay its debts as they become due in the course of its business or affairs, or exceeds, depending on the type of distribution, either the net assets or the surplus of the corporation.

While no shares of preferred stock are currently outstanding, the Texas Charter provides that (i) the Company’s Series A convertible preferred stock accrues dividends at the rate of 8% per annum, which are cumulative and payable semi-annually in either cash or registered shares of the common stock, at the Company’s election and (ii) the Company shall not declare, pay or set aside any dividends or other distributions on shares of common stock unless all accrued dividends have been fully paid and the holders of the Series A convertible preferred stock then outstanding shall first receive, or simultaneously receive, a dividend or distribution on each outstanding share of Series A convertible preferred stock in an amount equal to the product of (A) the dividend or distribution payable on each share of common stock and (B) the number of shares of common stock issuable upon conversion of a share of Series A convertible preferred stock.

Delaware

Under Delaware law, a corporation may, subject to any restrictions contained in its certificate of incorporation, pay dividends out of surplus and, if there is not surplus, out of net profits for the current and/or the preceding fiscal year, unless the capital of the corporation is less than the capital represented by issued and outstanding stock having preferences on asset distributions.

The Delaware Charter will provide that, subject to the preferential rights of any preferred stock, the holders of shares of common stock shall be entitled to receive, when, as and if declared by the board of directors, out of the assets of the Company which are by law available therefor, dividends payable either in cash, in property or in shares of capital stock.

Stock Redemption and Repurchase

Texas

As noted above, under Texas law, the purchase or redemption by a corporation of its shares constitutes a distribution. Accordingly, the discussion above relating to distributions is applicable to stock redemptions and repurchases.

Delaware

Under Delaware law, a corporation may purchase or redeem shares of any class except when its capital is impaired or would be impaired by such purchase or redemption. A corporation may, however, purchase or redeem out of capital, shares that are entitled upon any distribution of its assets to a preference over another class or series of its stock, or, if no shares entitled to such a preference are outstanding, any of its own shares, if such shares are to be retired and the capital reduced.

Indemnification of Directors and Officers

The parent company Acer Texas does not currently have indemnification agreements entered into directly with our directors or officers, however, our wholly owned subsidiary Private Acer has indemnification agreements with certain of its directors and officers which are substantially similar to the Delaware Indemnification Agreements. The directors and officers of the parent company Acer Texas and wholly owned subsidiary Private Acer overlap to a large extent. Private Acer had entered into these indemnification agreements with its directors and officers prior to the September 19, 2017 merger between Opexa Therapeutics, Inc., Opexa Merger Sub., Inc. and Private Acer. At the effective time of the merger, all of the directors and officers of Private Acer became the directors and officers of Acer Texas. Those indemnification agreements remain intact, and if Proposal 3 is approved, Acer Delaware intends to enter into the Delaware Indemnification Agreements directly with its directors and officers.

Texas and Delaware law have similar provisions and limitations regarding indemnification by a corporation of its officers, directors, employees and agents. The following is a summary comparison of the indemnification provisions of Texas and Delaware law:

Texas

Texas law permits a corporation to indemnify a director or former director, against judgments and expenses reasonably and actually incurred by the person in connection with a proceeding if the person: (i) acted in good faith, (ii) reasonably believed, in the case of conduct in the person’s official capacity, that the person’s conduct was in the corporation’s best interests, and otherwise, that the person’s conduct was not opposed to the corporation’s best interests, and (iii) in the case of a criminal proceeding, did not have a reasonable cause to believe the person’s conduct was unlawful. If, however, the person is found liable to the corporation, or is found liable on the basis he received an improper personal benefit, then indemnification under Texas law is limited to the reimbursement of reasonable expenses actually incurred and no indemnification will be available if the person is found liable for: (i) willful or intentional misconduct in the performance of the person’s duty to the corporation, (ii) breach of the person’s duty of loyalty owed to the enterprise, or (iii) an act or omission not committed in good faith that constitutes a breach of a duty owed by the person to the corporation.

The Texas Articles and the Texas Bylaws provide for indemnification of directors and officers (including advancement of expenses) to the fullest extent permitted by applicable law.

Delaware

Delaware law permits a corporation to indemnify directors, officers, employees, or agents against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by the person in connection with an action, suit or proceeding, other than an action by or in the right of the corporation, to which such director, officer, employee or agent may be a party, provided such a director, officer, employee or agent acted in good faith and reasonably believed: (i) in the case of a civil, administrative or investigative proceeding, that his or her conduct was in or not opposed to the best interests of the corporation, or (ii) in the case of a criminal proceeding, that he or she had no reasonable cause to believe his or her conduct was unlawful. In connection with an action by or in the right of the corporation against a director, officer, employee

or agent, the corporation has the power to indemnify such director, officer, employee or agent for expenses actually and reasonably incurred in connection with such suit: (i) if such person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, and (ii) if such person is found liable to the corporation, only if ordered by a court of law. Section 145 of the DGCL provides that such section is not exclusive of any other indemnification rights, which may be granted by a corporation to its directors, officers, employees or agents.

The Delaware Charter and Delaware Bylaws will provide for indemnification of directors and officers (including advancement of expenses) to the fullest extent permitted by applicable law.

Assuming that our shareholders approve this Proposal 3, Acer Delaware will enter into a Delaware Indemnification Agreement with each director and officer of Acer Delaware following the Reincorporation.

Procedure for Indemnification

Texas

Texas law provides that a determination that indemnification is appropriate must be made: (i) by a majority vote of the directors who, at the time of the vote, are disinterested and independent, regardless of whether such directors constitute a quorum, (ii) by a majority vote of a special committee of the board of directors if the committee is designated by a majority vote of the directors who at the time of the vote are disinterested and independent and is composed solely of one or more directors who are disinterested and independent, (iii) by special legal counsel selected by majority vote under (i) or (ii) above, (iv) by the shareholders in a vote that excludes those shares held by directors who, at the time of the vote, are not disinterested and independent, or (v) by a unanimous vote of the shareholders of the corporation.

Delaware

Delaware law provides that a determination that indemnification of a director or officer is appropriate must be made: (i) by a majority vote of directors who are not party to the proceeding, even though less than a quorum, (ii) by a committee of such directors designated by majority vote of such directors, even though less than a quorum, (iii) if there are no such directors or if such directors so direct, by independent legal counsel in a written opinion, or (iv) by stockholder vote.

Mandatory Indemnification

Texas

Under Texas law, indemnification by the corporation for reasonable expenses actually incurred is mandatory only if the director is wholly successful on the merits or otherwise, in the defense of the proceeding.

Delaware

Delaware law requires indemnification for expenses actually and reasonably incurred with respect to any claim, issue or matter on which the director is successful on the merits or otherwise, in the defense of the proceeding.

Insurance

Texas

Texas law allows a corporation to purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation against any liability asserted against such person and

incurred by such person in such a capacity or arising out of his status as such a person. Under Texas law, a corporation may also establish and maintain arrangements, other than insurance, to protect such persons, including a trust fund or surety arrangement.

Delaware

Delaware law is substantially the same as Texas law on this issue.

Persons Covered

Texas

Texas law expressly and separately addresses the indemnification of officers, employees and agents. The corporation may indemnify and advance expenses to an officer, employee or agent as provided by the corporation’s governing documents, general or specific action of the board of directors, resolution of the shareholders, contract, or common law. The corporation must indemnify an officer to the same extent as a director. The procedure for indemnification under Texas law summarized above need not be followed for officers, employees or agents.

Delaware

Delaware law provides the same indemnification rights to officers, employees and agents that it provides for directors.

Fiduciary Duties of Directors

Texas

Texas imposes duties of loyalty, care and obedience on directors of Texas corporations, but will generally not, absent fraud, impose liability upon anon-interested director unless the action challenged is outside of the expressed purpose of the corporation or inconsistent with an express limitation on authority. Directors of a Texas corporation owe fiduciary duties only to the corporation.

Delaware

Delaware imposes duties of care and loyalty on directors of Delaware corporations, subject to the business judgment rule which provides a presumption that a director acted on an informed basis, in good faith, and in the honest belief that the action taken was in the best interests of the corporation. Delaware imposes liability upon directors who willfully or recklessly disregard their duties as directors so as to constitute an utter failure to carry out their fiduciary duties. Directors of a Delaware corporation owe fiduciary duties both to the stockholders and the corporation.

Standard of Care

The standard of care required under Texas and Delaware law is substantially the same. In general, directors are charged with the duty in their decision-making process and oversight responsibilities to act as would a reasonably prudent person in the conduct of such person’s own affairs.

Limited Liability of Directors

Texas

Texas law permits a corporation to eliminate in its certificate of formation all monetary liability of a director to the corporation or its shareholders for conduct in the performance of such director’s duties. Texas law does

not, however, permit any limitation of the liability of a director for: (i) a breach of the duty of loyalty to the corporation or its shareholders, (ii) an act or omission not in good faith that constitutes a breach of duty of the person to the corporation or involves intentional misconduct or a knowing violation of law, (iii) a transaction from which the director obtains an improper benefit, or (iv) a violation of applicable statutes which expressly provide for the liability of a director.

The Texas Charter eliminates the monetary liability of a director to the fullest extent permitted by applicable law.

Delaware

Delaware law permits the adoption of a provision in the certificate of incorporation limiting or eliminating the monetary liability of a director to a corporation or its stockholders by reason of a director’s breach of the fiduciary duty of care. Delaware law does not, however, permit any limitation of the liability of a director for: (i) breaching the duty of loyalty to the corporation or its stockholders, (ii) failing to act in good faith, (iii) engaging in intentional misconduct or a knowing violation of law, (iv) obtaining an improper personal benefit from the corporation, or (v) declaring an illegal dividend or approving an illegal stock purchase or redemption.

The Delaware Charter will eliminate the monetary liability of a director to the fullest extent permitted by applicable law.

Forum Selection

Texas

Neither the Texas Charter nor the Texas Bylaws contain a forum selection provision.

Delaware

Section 115 of the DGCL expressly permits a corporation’s certificate of incorporation or bylaws to require that any or all “internal corporate claims” be brought solely and exclusively in any or all Delaware courts, and that no provision of a corporation’s certificate of incorporation or bylaws may prohibit bringing such claims in Delaware courts.

Subject to shareholder approval of Proposal 2E, our Board of Directors has proposed that the Delaware Charter will provide that unless Acer Delaware consents in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware shall be the sole and exclusive forum for (i) any derivative action or proceeding brought on behalf of Acer Delaware, (ii) any action asserting a claim of breach of a fiduciary duty owed by any director, officer or other employee of Acer Delaware to Acer Delaware or Acer Delaware’s stockholders, (iii) any action asserting a claim arising pursuant to any provision of the DGCL, or (iv) any action asserting a claim governed by the internal affairs doctrine.

Shareholder Rights Plans

Texas

Texas statutorily approves shareholder rights plans.

Delaware

Delaware courts have generally allowed the use of shareholder rights plans by a corporation if their adoption is reasonable in response to a reasonably identified threat posed.

Considerations of Directors

Texas

Texas corporate law includes statutory approval of directors considering both the long-term and short-term interests of the corporation and the shareholders.

Delaware

Delaware does not have a statute stating what constituencies the board may consider when making decisions.

Shareholder Actions

Texas

Texas generally requires that lawsuits against directors be brought derivatively by the corporation only after making demand on the corporation’s board setting out the contours of the demand. Texas law may, in certain circumstances, such as in a proceeding determining liability of directors, allow for a jury trial.

Delaware

Delaware allows certain lawsuits to be brought against directors directly by shareholders, in some instances, without making a demand on the corporation’s board. Generally, lawsuits are tried before a Delaware chancellor without a jury.

Interest of Certain Persons in Matters to be Acted Upon

In considering the recommendations of the Board, our shareholders should be aware that certain of our directors and officers have interests in the transaction that are different from, or in addition to, the interests of the shareholders generally. For instance, the Reincorporation may be of benefit to our directors and officers by reducing their potential personal liability, increasing the scope of permitted indemnification, and in other respects. Further, each of the Company’s directors and officers has an interest in the approval of the Delaware Indemnification Agreement, which, subject to certain limitations, imposes on the Company the obligation to indemnify such director or officer in the event she or he is made party to an action, suit or proceeding, by reason of the fact that she or he is or was a director, officer, employee or agent of the Company. The Company intends to enter into the Delaware Indemnification Agreement with each of its current officers and directors. The Company is not currently aware of any action, suit or proceeding pending or threatened which would require the Company to indemnify any director or officer as a result of being a party to the Delaware Indemnification Agreement. The Board was aware of these interests and considered them, among other matters, in reaching its decision to approve the Reincorporation and to recommend that our shareholders vote in favor of this proposal.

Federal Income Tax Consequences of the Reincorporation

The discussion of U.S. federal income tax consequences set forth below is for general information only and does not purport to be a complete discussion or analysis of all potential tax consequences that may apply to a shareholder.Shareholders are urged to consult their tax advisors to determine the particular tax consequences of the Reincorporation, including the applicability of federal, state, foreign and other tax laws.

The Reincorporation provided for in the Plan of Conversion is intended to be atax-free reorganization under Section 368(a) of the Internal Revenue Code. Assuming the reincorporation qualifies as a reorganization, no gain or loss should be recognized to the holders of our capital stock as a result of the consummation of the Reincorporation, and no gain or loss will be recognized by us. Shareholders should have the same basis in the

Acer Delaware common stock received pursuant to the Reincorporation as they had in the shares of Acer Texas common stock held by you as of immediately prior to the time the Reincorporation is consummated. The holding period with respect to Acer Delaware common stock should include the period during which corresponding shares of Acer Texas common stock were held, provided the latter was held by you as a capital asset at the time of consummation of the Reincorporation.

Accounting Treatment of the Reincorporation

We expect that the Reincorporation will have no effect on the Company from an accounting perspective because there is no change in the entity as a result of the Reincorporation. Accordingly, the historical financial statements of the Company, which previously have been reported to the SEC on Forms10-K and10-Q, among others, as of and for all periods through the date of this Proxy Statement, will remain the financial statements of Acer Delaware following the Reincorporation.

Regulatory Approval

The Reincorporation will not occur until the Company has made all required filings with and received all required consents of all governmental authorities, including the filing of the Delaware Certificate of Conversion and the Delaware Charter with the Delaware Secretary of State, and the filing of the Texas Certificate of Conversion with the Texas Secretary of State, and satisfied applicable notification requirements of The Nasdaq Stock Market.

Dissenters’ Rights

Under Texas law, shareholders are not entitled to dissenters’ rights with respect to the Reincorporation.

Subsidiary Merger to Eliminate Holding Company Structure

We currently have a holding company structure, with Private Acer being a wholly owned subsidiary of Acer Texas. In order to simplify our corporate organization, eliminate costs associated with our holding company structure, reduce overhead expenses and take full advantage of the benefits of Delaware law, assuming the Reincorporation is approved by our shareholders, we also intend to eliminate our holding company structure by contemporaneously merging our wholly owned subsidiary Private Acer with and into the Company, resulting in a single Delaware corporation (the “Subsidiary Merger”). No action by the Company’s shareholders is required in order for the Company to effect the Subsidiary Merger. The Subsidiary Merger will not result in any material change in our business, assets or financial position or in the persons who constitute our Board, including those persons who are elected at the Annual Meeting. The individuals serving as our officers immediately before the Subsidiary Merger will continue to serve as our officers after the Subsidiary Merger.

Because our wholly owned subsidiary Private Acer is currently a Delaware corporation, and only one entity may be incorporated at a particular time with that name, the initial Delaware Charter for Acer Delaware will use a placeholder name of “Acer Reincorporation, Inc.” Implementing the Subsidiary Merger of Private Acer with and into Acer Delaware will allow the name of “Acer Therapeutics Inc.” to become available in Delaware and, as part of the Subsidiary Merger, Acer Delaware will change its name from “Acer Reincorporation, Inc.” to “Acer Therapeutics Inc.”

Upon filing of the certificate of ownership and merger with the Secretary of State of the State of Delaware, (i) the legal existence of Private Acer as a separate corporation and wholly owned subsidiary will cease, (ii) Acer Delaware, as the surviving corporation, will succeed to the assets and assume the liabilities of our wholly owned subsidiary Private Acer, and (iii) Acer Delaware will change its name from “Acer Reincorporation, Inc.” (the placeholder name used in the initial Delaware Charter) to “Acer Therapeutics Inc.”

THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” APPROVAL OF THE REINCORPORATION

PROPOSAL 4

APPROVAL OF THE 2018 STOCK INCENTIVE PLAN

We are asking our shareholders to approve our 2018 Stock Incentive Plan (the “2018 Plan”) at the Annual Meeting. On March 1, 2018, the Board approved the 2018 Plan, subject to shareholder approval. If this Proposal 4 is approved and the 2018 Plan becomes effective, no further grants will be made under the Amended and Restated 2010 Stock Incentive Plan (the “2010 Plan”) and the 2013 Stock Incentive Plan, as amended (the “2013 Plan”), of Private Acer which we assumed in accordance with Nasdaq listing standards, which generally require shareholder approval of all material revisions to equity compensation plans, and also for purposes of Section 162(m) of the Internal Revenue Code. On March 29, 2016 our Board amended and restatedmerger on September 19, 2017. All outstanding stock awards granted under the 2010 Plan and the 2013 Plan will continue to be subject to shareholder approval,the terms and conditions as set forth in order to (i) increase the agreements evidencing such stock awards and the terms of the 2010 Plan or the 2013 Plan, as applicable.

If our shareholders approve the 2018 Plan, the total number of shares of our common stock reserved for issuance by an additional 650,000under the 2018 Plan will initially consist of (i) 500,000 shares andplus (ii) reset the number of stock-basedshares subject to outstanding awards issuable to a participant in any calendar year. As of December 31, 2015, options to purchase 379,306 shares were outstanding under the 2010 Plan, 60,810 shares remained available for future issuance under the 2010 Plan and optionsthe 2013 Plan that are forfeited or terminate prior to purchase 38,098 shares were outstandingexercise or settlement and would otherwise be returned to the share reserve under the Company’s 2004 Compensatory Stock Option2010 Plan (“2004 Plan”). All share amounts set forthor the 2013 Plan, as applicable, plus the number of shares subject to vesting restrictions under the 2010 Plan or the 2013 Plan that are subsequently forfeited, plus any reserved shares not issued or subject to outstanding grants, up to a maximum of 635,170 shares. In addition, the number of shares that have been authorized for issuance under the 2018 Plan will be automatically increased on the first day of each fiscal year beginning on January 1, 2019 and ending on (and including) January 1, 2028, in this proxy statement reflectan amount equal to the 1-for-4 reverse splitlesser of (i) 4% of the outstanding shares of our common stock effected on December 14, 2012 and the 1-for-8 reverse split of our common stock effected on September 28, 2015.

In order for certain compensation to be considered performance-based, and therefore deductible under Section 162(m)last day of the Internal Revenue Code, material terms of the potential performance goals/ measures applicable to that compensation must be approved by shareholders at least every five years. For purposes of Section 162(m) of the Internal Revenue Code, the material terms of the performance goals that we are asking you to approve consist of: (i) the individuals eligible to receive compensation,immediately preceding fiscal year, or (ii) a description of the business criteria/performance measures on which the performance goals are based, and (iii) the maximumanother amount of compensation that could be paid to any individual. Approval of this Proposal 2 will constitute approval of the material terms of the performance criteria, as summarized below.

The Board initially adopted the Opexa Therapeutics, Inc. 2010 Stock Incentive Plan on September 2, 2010 for the granting of equity incentive awards to employees, directors and consultants of Opexa, and the Plan was initially approved(including zero) determined by our shareholders on October 19, 2010. On September 25, 2013, the Board amended and restated the 2010 Plan and it was approved by our shareholders on November 8, 2013, in order to (i) increase the number of shares of common stock reserved for issuance by 375,000 shares and (ii) reset the number of stock-based awards issuable to a participant in any calendar year.Directors (“Board”).

Why You Should Vote for Approval of our Amended and Restated 20102018 Stock Incentive Plan

Stock OptionsEquity Awards Are an Important Part of Our Compensation Philosophy

The 20102018 Plan is critical to our ongoing effort to build shareholder value. As discussed in the section entitled “Compensation Overview,” equityEquity incentive awards are central to our compensation program. Our Compensation Committee and Board believe that our ability to grant stock optionsequity incentives to new and existing employees has helped us attract, retain and motivate key talent. SinceFor example, since the potential value of stock options is realized only if our share price increases, this form of compensation provides a strong incentive for employees to work to grow the business and build shareholder value, and is most attractive to employees who share the entrepreneurial spirit that we believe is key to making our company a success.

The Board of Directors believes the2018 Plan will also provide us with continued flexibility in designing equity incentives in an environment where a number of companies have moved from traditional option grants to other stock awards, including restricted stock awards, stock appreciation rights, restricted stock unit awards, performance stock awards and performance cash awards. Accordingly, the 2018 Plan will allow us to utilize a broad array of equity incentives in order to secure and retain the services.

Our 2010 Plan is Running Low on Shares and our 2013 Plan Share Reserve has been Depleted

Grants of equity awards to our employees, consultants, executive officers and directors are currently made only from the 2010 Plan. All available shares under the 2013 Plan are currently subject to outstanding awards and no further awards may be made thereunder. After carefully forecasting, we anticipate that the 2010 Plan will not have any remaining shares in its share reserve by the end of the second quarter of 2018, and we will not be able to issue equity to our employees, consultants, executive officers and directors unless our shareholders approve a new stock plan. While we could increase cash compensation if we are unable to grant equity incentives, we anticipate that we will have difficulty attracting, retaining, and motivating our employees, consultants, executive officers and directors if we are unable to make equity grants to them. Stock incentive awards are a more effective executive compensation vehicle than cash at a growth-oriented, entrepreneurial company because they deliver high potential value with a smaller impact on current income and cash flow. Therefore, we are asking our shareholders to approve the 2018 Plan.

The Number of Shares Proposed for Approval is Reasonable

As of December 31, 2017, options to purchase 298,600 shares were outstanding under the 2010 Plan, 159,572 shares remained available for future issuance under the 2010 Plan, prior to its amendment is inadequate to achieve the purposeand 11,998 shares of the 2010 Plan in the future.

The Number of Shares Proposed for the Increase is Reasonable

When our shareholders originally approved the 2010 Plan, a total reserve of 78,125 shares was established, plus an additional number of sharescommon stock had been issued subject to forfeiture restrictions pursuant to restricted stock options outstanding under our predecessor 2004 Plan at the time the 2010 Plan was originally adopted in 2010 that are forfeited or terminate prior to exerciseawards and would otherwise be returned to the share reserve under the 2004 Plan, and any reserved shares not issued or subject to outstanding grants at the time the 2010 Plan was originally adopted in 2010, up to a maximum of 64,152 shares. The 2010 Plan was amended on September 25, 2013 to add an additional 375,000 shares.option exercises thereunder. As of December 31, 2015, an additional 24,6432017, options to purchase 165,000 shares were outstanding under the 2013 Plan, no shares remained available for future issuance under the 2013 Plan, and no shares of common stock had been addedissued subject to forfeiture restrictions pursuant to restricted stock awards or option exercises thereunder. Stock options and restricted stock awards are the only types of awards that have been issued under the 2010 Plan fromand the 2004 Plan as a result2013 Plan. The weighted average exercise price of all options outstanding under the rollover provision. Our 2010 Plan and the 2013 Plan is currently$11.23 per share and the weighted average remaining term of such options is approximately 9.5 years as of December 31, 2017. A total of 7,497,433 shares of our common stock were outstanding as of December 31, 2017.

The 2010 Plan and the 2013 Plan are our only equity compensation planplans under which we may make equity awards.

At After carefully forecasting our anticipated growth rate for the timenext few years, we originally adoptedbelieve that the base amount of 500,000 shares, in addition to shares reserved under or that would be returned to the 2010 Plan we anticipated thator the original share reserve would2013 Plan together with the potential annual increase of up to 4% of the outstanding shares of our common stock outstanding on the first day of each fiscal year, will be sufficient for at least three years’ worth of equity grants. In 2013, we returnedgrants under our current compensation program. We anticipate returning to shareholders to obtain approval to addfor additional shares that we believed would be sufficient for at least an additional three years’ worth of equity grants.in 2021, but may elect to do so sooner if our growth plan accelerates.

We believe our equity granting practices have been maintained at a reasonable level, and we do not believe that the proposed 650,000500,000 share increasereserve will be unduly dilutive to stockholders:shareholders:

10

Another common measure of dilution is “burn rate,” which shows how rapidly a company is depleting the shares reserved for issuance under its equity compensation plans, but without taking into account award cancellations or forfeitures. It is generally defined as the number of equity awards granted in the year, divided by the weighted average number of common shares outstanding during the year. Our annualA historical burn rate was approximately 2.5%calculation is not meaningful for us at this point because all prior outstanding equity awards were cancelled in 2015, approximately 5.5% in 2014connection with the September 2017 Merger between the Company, Private Acer and approximately 3.8% in 2013.

11

Description of the Amended and Restated 20102018 Stock Incentive Plan

The material features of the 20102018 Plan are outlined below. This summary is qualified in its entirety by reference to the complete text of the 20102018 Plan. Shareholders are urged to read the actual text of the 20102018 Plan in its entirety, which is filed with this Proxy Statement asAppendix AG and is available at http://www.sec.gov.

Background and Purpose

The terms of the 20102018 Plan provide for the grant of stock options, restricted stock, stock appreciation rights, restricted stock units, performance-based awards and performancecash-based awards that may be settled in cash, stock or other property.

The purpose of the 20102018 Plan is to provide a meansenhance our ability to attract, retain and motivate persons who make (or are expected to make) important contributions to us by which employees, directors,providing these individuals with equity ownership and consultants may be given an opportunity to purchase our common stock to assist us in securing and retaining the services of such persons, to secure and retain the services of persons capable of filling such positions, and to provide incentives for such persons to exert maximum efforts for our success.other incentive opportunities.

Shares Available for Awards

If this proposal 2Proposal 4 is approved, the total number of shares of our common stock reserved for issuance under the 20102018 Plan (the “Share Reserve”), will consist of:

AsIn addition, the number of December 31, 2015, options to purchase 379,306 shares were outstanding under the 2010 Plan, 60,810 shares remained availablethat have been authorized for future issuance under the 20102018 Plan will be automatically increased on the first day of each fiscal year beginning on January 1, 2019 and 37,652 sharesending on (and including) January 1, 2028, in an amount equal to the lesser of common stock had been issued pursuant to restricted stock awards thereunder. As(i) 4% of such date, options to purchase 38,098 shares werethe outstanding under our 2004 Plan. Stock options and restricted stock awards are the only types of awards that have been issued under the 2010 Plan. The weighted average exercise price of all options outstanding under both the 2004 Plan and the 2010 Plan is $18.04 per share, and the weighted average remaining term of such options is approximately 7.7 years as of December 31, 2015. A total of 6,982,909 shares of our common stock were outstanding ason the last day of December 31, 2015.the immediately preceding fiscal year, or (ii) another amount (including zero) determined by our Board.

Shares subject to awards granted under the 20102018 Plan that are forfeited or terminate before being exercised or settled, or are not delivered to the participant because such award is settled in cash, will again become

available for issuance under the 20102018 Plan. Shares withheld to satisfy the grant, exercise price or tax withholding obligation related to an award will again become available for issuance under the 20102018 Plan. However, shares that have actually been issued will not again become available unless forfeited. If any shares of common stock issued pursuant to a stock award are forfeited back to us because of the failure to meet a contingency or condition required to vest such shares in the participant, then the shares which are forfeited will revert to and again become available for issuance under the 2010 Plan.2018 Plan unless forfeited. No more than 1,167,2771,135,170 shares may be delivered upon the exercise of incentive stock options granted under the 20102018 Plan plus, to the extent allowable under applicable law, any shares that again become available for issuance under the 20102018 Plan.

If this proposal 2Proposal 4 is approved, no participant in the 20102018 Plan can receive option grants restricted shares,or stock appreciation rights or stock units totaling more than an aggregate of 300,000250,000 shares in any calendar year, except in the participant’s first year of employment in which the participant may receive equitytwo times this amount. The maximum aggregate number of shares that may be subject to restricted stock awards totaling up to 600,000 shares.or stock units in any calendar year is 250,000 shares, except in the participant’s first year of employment in which the participant may receive two times that amount. No participant in the 20102018 Plan may be paid more than an aggregate of $2.5$2.0 million in cash during any calendar year with respect to equity awards that are payable in cash.

Eligibility

Incentive stock options, or ISOs, within the meaning of Section 422 of the Internal Revenue Code, as amended (the “Code”), may be granted under the 20102018 Plan only to our employees (including executive officers) and employees of our parent or subsidiary. Our employees (including executive officers), consultants and directors, and the employees (including executive officers) and consultants of our affiliates are eligible to receive all other types of awards under the 2010 Plan.2018 Plan, including nonstatutory stock options, or NSOs. All of our 2610 employees as of March 10, 20161, 2018 (including officers), as well as our directors and consultants, are eligible to participate in the 20102018 Plan.

12

Administration

The 20102018 Plan is administered by our Board, which may in turn delegate authority to administer the plan to a committee such as our Compensation Committee.Committee, referred to herein as the 2018 Plan administrator. Subject to the terms of the 20102018 Plan, our Board (or, as applicable, our Compensation Committee)the 2018 Plan administrator will determine recipients, the numbers and typesnumber of stockshares or amount of cash subject to awards to be granted, whether an option is to be an ISO or NSO and the terms and conditions of the stock awards, including the period of their exercisability and vesting. Subject to the limitations set forth below, our Board (or, as applicable, our Compensation Committee)the 2018 Plan administrator will also determine the exercise price of options granted under the 20102018 Plan.

Repricing

The 20102018 Plan expressly provides that, without the approval of the shareholders, the Board or Compensation Committee shall2018 Plan administrator does not have the authority to reduce the exercise price of any outstanding stock options or stock appreciation rights under the plan (except in connection with certain corporate transactions, such as stock splits, certain dividends, recapitalizations, reorganizations, mergers, spin-offs and the like), or cancel any outstanding underwater stock options or stock appreciation rights in exchange for cash or new stock awards under the 20102018 Plan.

Cancellation or Clawback of Awards

The 2018 Plan administrator may, to the extent permitted by applicable law and stock exchange rules or by any of our policies, cancel or require reimbursement of any awards granted, shares issued or cash received upon the vesting, exercise or settlement of any awards granted under the 2018 Plan or the sale of shares underlying such awards.

Stock Options

A stock option is the right to purchase a certain number of shares of stock, at a certain exercise price, in the future. Stock options will be granted pursuant to stock option agreements. The exercise price for an option cannot

be less than 100% of the fair market value of the common stock subject to the option on the date of grant. Options granted under the 2010 Plan will vest at the rate specified in the option agreement. Incentive stock optionsISOs granted to any holder of more than 10% of the voting shares of our company must have an exercise price of at least 110% of the fair market value of our common stock on the date of grant. Options granted under the 2018 Plan will vest at the rate specified in the option agreement, and the extent to which the optionholder will have the right to exercise the option following termination of the optionholder’s service with us will be set forth in the option agreement.

The term of stock options granted under the 20102018 Plan may not exceed ten years (five years in the case of an incentive stock optionISO granted to any holder of more than 10% of our voting shares). Each stock option agreement will set forth any limitations on the right of the option holder to exercise the stock option following termination of service with us or any affiliate of ours.

Acceptable forms of consideration for the purchase of our common stock issued under the 20102018 Plan will be determined by our Board (or, as applicable, our Compensation Committee)the 2018 Plan administrator and may include cash, common stock previously owned by the option holder, payment through a broker assisted cashless exercise, “net exercise” or other legal consideration approved by our Board (or, as applicable, our Compensation Committee).the 2018 Plan administrator.

Generally, an option holder may not transfer a stock option other than by will or the laws of descent and distribution, unless otherwise permitted under the terms of the applicable stock option agreement.

ISO Limitations

The aggregate fair market value, determined at the time of grant, of shares of our common stock with respect to which incentive stock options (“ISOs”)ISOs may be exercisable for the first time by an optionholderoption holder during any calendar year under all of our stock plans may not exceed $100,000. The options or portions of options that exceed this limit are treated as nonstatutory stock options (“NSOs”).NSOs. The aggregate maximum number of shares of common stock that may be issued pursuant to the exercise of ISOs shall be no more than 1,167,2771,135,170 shares plus, to the extent allowable under applicable law, any shares that again become available for issuance under the 20102018 Plan. No ISO may be granted to any person who, at the time of the grant, owns or is deemed to own stock possessing more than 10% of our total combined voting power or that of any affiliate.

Restricted Stock Awards

Restricted stock awards will be granted pursuant to restricted stockis a share award agreements. A restricted stock award may be granted in consideration for the recipient’s services performed for us or an affiliate of ours. Shares of our common stock acquired under a restricted stock awardthat may be subject to forfeiture to usvesting conditioned upon continued service, the achievement of performance objectives or the satisfaction of any other condition as specified in accordance with a vesting schedule to be determined by our Board (or, as applicable, our Compensation Committee). Rights to acquire shares of our common stock under a restricted stock award may be transferred only uponagreement. Participants who are granted restricted stock awards generally have all of the rights of a shareholder with respect to such stock, other than the right to transfer such stock prior to vesting. Subject to the terms of the 2018 Plan, the 2018 Plan administrator will determine the terms and conditions as areof any restricted stock award, including any vesting arrangement, which will be set forth in thea restricted stock agreement to be entered into between us and each recipient. Restricted stock may be awarded for such consideration as the 2018 Plan administrator may determine, including without limitation cash, cash equivalents, full-recourse promissory notes, future services or services rendered prior to the award, agreement.without cash payment by the recipient.

Stock Appreciation Rights

Stock appreciation rights typically will provide for payments to the recipient based upon increases in the price of our common stock over the exercise price of the stock appreciation right. The exercise price of a stock appreciation right will be determined by our Board (or, as applicable, our Compensation Committee),the 2018 Plan administrator, which shall not be less than the fair market value of our common stock on the date of grant. Our Board (or, as applicable, our Compensation Committee)The 2018 Plan administrator may elect to pay stock appreciation rights in cash or in common stock or in a combination of cash and common stock.

13

Restricted Stock Unit Awards

Restricted stock unit awards will be granted pursuantStock units give recipients the right to restricted stock unit award agreements. We will settleacquire a restricted stock unit award by deliveryspecified number of shares of ourstock (or cash amount) at a future date upon the satisfaction of certain conditions, including any vesting arrangement, established by the

2018 Plan administrator and as set forth in a stock unit agreement. Unlike restricted stock, the stock underlying stock units will not be issued until the stock units have vested and are settled, and recipients of stock units generally will have no voting or dividend rights prior to the time the vesting conditions are satisfied and the award is settled. At the 2018 Plan administrator’s discretion, stock units may provide for the right to dividend equivalents. The 2018 Plan administrator may elect to settle vested stock units in cash or in common stock by cash, or byin a combination of cash and common stock. Subject to the terms of the 2018 Plan, the 2018 Plan administrator will determine the terms and conditions of any stock as deemed appropriate by our Board (or, as applicable, our Compensation Committee) andunit award, which will be set forth in the restricteda stock unit agreement to be entered into between us and each recipient.

Cash-based Awards

A cash-based award agreement. Dividend equivalentsis denominated in cash. The 2018 Plan administrator may grant cash-based awards in such number and upon such terms as it shall determine. Payment, if any, will be credited in respect of shares of our common stock covered by a restricted stock unit award. Restricted stock unit awards may be subject to vestingmade in accordance with a vesting schedule tothe terms of the award, and may be made in cash or in shares of common stock, as determined by our Board (or, as applicable, our Compensation Committee). Except as otherwise provided in the applicable restricted stock unit award agreement, restricted stock units that have not vested will be forfeited upon the participant’s termination of continuous service for any reason.2018 Plan administrator.

Performance Awards

The 20102018 Plan provides that Awardsawards may be granted, issued, vested or retained based upon the attainment during a certain period of time of certain performance goals. The length of any performance period, the performance goals to be achieved during the performance period, and the measure of whether and to what degree such performance goals have been attained will generally be determined by our Board (or, as applicable, our Compensation Committee).the 2018 Plan administrator.

Performance goals under the 20102018 Plan shallwill be determined by our Board (or, as applicable, our Compensation Committee),the 2018 Plan administrator, based on or related to one or more of the following performance criteria:

Changes to Capital Structure

In the event that there is a specified type of change in our capital structure, such as a stock split or stock dividend, the class2018 Plan administrator will make appropriate and equitable adjustments to the number of shares reserved for issuance under the 20102018 Plan, (including share limits) and the class andlimitations regarding the total number of shares underlying awards given to an individual participant in any calendar year, the number of shares that can be issued as ISOs, the number of shares subject to outstanding awards and the exercise price under each outstanding option or strike price, if applicable, of all outstanding stock awards will be appropriately and equitably adjusted.appreciation right.

Corporate Transactions

In the event of certain corporate transactions, alla merger or other reorganization, outstanding stock awards underwill be subject to the 2010 Planagreement of merger or reorganization. Such agreement may be assumed, continuedprovide for (i) the continuation of the outstanding awards by us, if we are a surviving corporation, (ii) the assumption or substituted forsubstitution of the outstanding awards by any surviving entity. If the surviving entity electscorporation or its parent or subsidiary, (iii) immediate vesting, exercisability and settlement of the outstanding awards followed by their cancellation (whether or not then vested or exercisable), or (iv) settlement of the intrinsic value of the outstanding awards (whether or not vested or exercisable) in cash, cash equivalents, or equity (including cash or equity subject to assume, continuedeferred vesting and delivery consistent with the vesting restrictions applicable to such award or substitute forthe underlying shares) followed by cancellation of such awards the vesting(whether or exercisability of such stocknot then vested or exercisable). We have no obligation to treat all awards, may be accelerated in full and then terminated, if and to the extent not exercised atall awards held by a participant or prior to the effective timeall awards of the corporate transaction,same type similarly in connection with a merger or we may terminate the stock awards upon payment of their intrinsic value in cash or cash equivalents.other reorganization.

Plan Amendments and Termination

Our Board will have the authority to amend or terminate the 20102018 Plan. However, in general, no amendment or termination of the plan2018 Plan may materially impair any rights under awards already granted to a participant unless agreed to by the affected participant. We will obtain shareholder approval of any amendment to the 20102018 Plan if required by applicable law.

14

Plan Termination

Unless sooner terminated by the Board, the 2010 Plan will automatically terminate on September 1, 2020, the day before No ISO may be granted after the tenth anniversary of the earlier of (i) the date the 20102018 Plan was originally adopted by our Board, and (ii) the Board.date the plan was approved by our shareholders.

U.S. Federal Income Tax Consequences

The information set forth below is a summary only and does not purport to be complete. The information is based upon current federal income tax rules and therefore is subject to change when those rules change. Because the tax consequences to any recipient may depend on his or her particular situation, each recipient should consult the recipient’s tax adviser regarding the federal, state, local, and other tax consequences of the grant or exercise of an award or the disposition of stock acquired as a result of an award. The 20102018 Plan is not qualified under the provisions of Section 401(a) of the Internal Revenue Code, (the “Code”), and is not subject to any of the provisions of the Employee Retirement Income Security Act of 1974.1974, as amended. Our ability to realize the benefit of any tax deductions described below depends on our generation of taxable income.

Nonstatutory Stock Options

Generally, there is no taxation upon the grant of an NSO where the option is granted with an exercise price equal to the fair market value of the underlying stock on the grant date. On exercise, an optionee will recognize ordinary income equal to the excess, if any, of the fair market value on the date of exercise of the stock over the exercise price. If the optionee is employed by us or one of our affiliates, that income will be subject to withholding tax. The optionee’s tax basis in those shares will be equal to their fair market value on the date of exercise of the option, and the optionee’s capital gain holding period for those shares will begin on that date.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the optionee.

Incentive Stock Options

The 20102018 Plan provides for the grant of stock options that qualify as “incentive stock options,” as defined in Section 422 of the Code. Under the Code, an optionee generally is not subject to ordinary income tax upon the grant or exercise of an ISO. If the optionee holds a share received on exercise of an ISO for more than two years from the date the option was granted and more than one year from the date the option was exercised, which is referred to as the required holding period, the difference, if any, between the amount realized on a sale or other taxable disposition of that share and the holder’s tax basis in that share will be long-term capital gain or loss.

If, however, an optionee disposes of a share acquired on exercise of an ISO before the end of the required holding period, which is referred to as a disqualifying disposition, the optionee generally will recognize ordinary income in the year of the disqualifying disposition equal to the excess, if any, of the fair market value of the share on the date the ISO was exercised over the exercise price. However, if the sales proceeds are less than the fair market value of the share on the date of exercise of the option, the amount of ordinary income recognized by the optionee will not exceed the gain, if any, realized on the sale. If the amount realized on a disqualifying disposition exceeds the fair market value of the share on the date of exercise of the option, that excess will be short-term or long-term capital gain, depending on whether the holding period for the share exceeds one year.

For purposes of the alternative minimum tax, the amount by which the fair market value of a share of stock acquired on exercise of an ISO exceeds the exercise price of that option generally will be an adjustment included in the optionee’s alternative minimum taxable income for the year in which the option is exercised. In computing alternative minimum taxable income, the tax basis of a share acquired on exercise of an ISO is increased by the amount of the adjustment taken into account with respect to that share for alternative minimum tax purposes in the year the option is exercised.

We are not allowed an income tax deduction with respect to the grant or exercise of an ISO or the disposition of a share acquired on exercise of an ISO after the required holding period. If there is a disqualifying disposition of a share, however, we are allowed a deduction in an amount equal to the ordinary income includible in income by the optionee, subject to Section 162(m) of the Code and provided that amount constitutes an ordinary and necessary business expense for us and is reasonable in amount, and either the employee includes that amount in income or we timely satisfy our reporting requirements with respect to that amount.

Restricted Stock Awards

Generally, the recipient of a restricted stock award will recognize ordinary income at the time the stock is received equal to the excess, if any, of the fair market value of the stock received over any amount paid by the recipient in exchange for the stock. If, however, the stock is not vested when it is received (for example, if the employee is required to work for a period of time in order to have the right to sell the stock), the recipient generally will not recognize income until the stock becomes vested, at which time the recipient will recognize

ordinary income equal to the excess, if any, of the fair market value of the stock on the date it becomes vested over any amount paid by the recipient in exchange for the stock. A recipient may, however, file an election with the Internal Revenue

15

Service, within 30 days of his or her receipt of the stock award, to recognize ordinary income, as of the date the recipient receives the award, equal to the excess, if any, of the fair market value of the stock on the date the award is granted over any amount paid by the recipient in exchange for the stock.

The recipient’s basis for the determination of gain or loss upon the subsequent disposition of shares acquired from stock awards will be the amount paid for such shares plus any ordinary income recognized either when the stock is received or when the stock becomes vested.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the recipient of the stock award.

Stock Appreciation Rights

Generally, there is no taxation upon the grant of a stock appreciation right where the stock appreciation right is granted with an exercise price not less than the fair market value of the underlying stock on the grant date. On exercise, the recipient of a stock appreciation right will recognize ordinary income equal to the amount of cash or the value of the shares of common stock we distribute to the recipient. If the recipient is employed by us or one of our affiliates, that income will be subject to withholding tax. The recipient’s tax basis in the shares received, if any, will be equal to their fair market value on the date of exercise of the stock appreciation right, and the recipient’s capital gain holding period for those shares will begin on that date.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code and the satisfaction of any tax reporting obligations, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the recipient of the stock appreciation right.

Restricted Stock Units

Generally, the recipient of a stock unit structured to conform to the requirements of Section 409A of the Code or an exception to Section 409A of the Code will recognize ordinary income at the time the stock is delivered equal to the excess, if any, of the fair market value of the shares of our common stock received over any amount paid by the recipient in exchange for the shares of our common stock.

The recipient’s basis for the determination of gain or loss upon the subsequent disposition of shares acquired from stock units will be the amount, if any, paid for such shares plus any ordinary income recognized when the stock is delivered.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the recipient of the stock award.

Section 162 Limitations

Compensation of persons who are “covered employees” is subject to the tax deduction limits of Section 162(m) of the Code. AwardsPrior to the enactment of the Tax Cuts and Jobs Act (the “TCJA”) on December 22, 2017, awards that qualifyqualified as “performance-based compensation” arewere exempt from Section 162(m), thereby permitting us to claim the full federal tax deduction otherwise allowed for such compensation. The 2010 PlanThis exception was eliminated by the TCJA. However, pending further guidance, this exception may still be available under state law allowing us to claim the full state deduction otherwise allowed for such compensation. In addition, the TCJA includes a transition rule under which the change described above will not apply to compensation payable

pursuant to a written binding contract that was in effect on November 2, 2017 and is intendednot materially modified after that date. To the extent applicable to enable the Board orour existing contracts and awards, our Compensation Committee as applicable, to grant awards that will be exempt from the deduction limitsmay avail itself of Section 162(m).this transition rule.

New Plan Benefits

Our Board and Compensation Committee have not made any determination with respect to future awards under the 20102018 Plan, and any allocation of such awards will be made only in accordance with the provisions of the 20102018 Plan. Because awards under the 2018 Plan are subject to the discretion of the Board or Compensation Committee, as applicable, awards and benefits under the 20102018 Plan for the current or any future year are not determinable. Future option exercise prices under the 20102018 Plan are not determinable because they will be based upon the fair market value of our common stock on the date of grant.

In fiscal 2015,2017, our Named Executive Officers received option grants under the 2010 Plan as set forth in this Proxy Statement in the table entitled “2015“2017 Outstanding Equity Awards at FiscalYear-End” under the caption “Executive Compensation and Other Information.” In fiscal 2015, our 2017, certainnon-employee directors received option grants and restricted stock awards under the 2010 Plan as set forth under the heading “2015“2017 Director Compensation.”

16

In addition,The 2018 Plan will become effective if, and when, this Proposal 4 is approved by our shareholders. The Board approved the following table sets forth2018 Plan on March 1, 2018, subject to shareholder approval of the equity-based awards that were granted during the fiscal year ended December 31, 2015 under the 2010 Plan to each of our Named Executive Officers, our current executive officers, as a group, our other employees who are not executive officers, as a group, and our non-employee directors, as a group.2018 Plan.

Securities Authorized for Issuance Under Equity Compensation Plans

The following table sets forth information, as of December 31, 2015,2017, with respect to our compensation plans under which common stock is authorized for issuance, whichissuance. These plans consist of ourthe 2010 Stock Incentive Plan and its predecessor, our June 2004 Compensatory Stock Optionthe 2013 Plan. We believe that the exercise price for all of the options granted under these plans reflect at least 100% of fair market value on the dates of grant for the options at issue.

Equity Compensation Plan Information

The Board of Directors recommends a voteTHE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” approval of the Amended and Restated 2010 Stock Incentive Plan.APPROVAL OF THE 2018 STOCK INCENTIVE PLAN

PROPOSAL 35

ADVISORY VOTE ON THE COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS

Section 14A of the Exchange Act, in conjunction with the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “Dodd-Frank Act”), requires companies that are subject to the SEC’s proxy rules and regulations to hold a shareholder vote to approve, on an advisory (non-binding) basis, the compensation of their Named Executive Officers as disclosed in their proxy statements in accordance with the SEC’s rules. This proposal, commonly known as a “say-on-pay” proposal, gives you, as a shareholder, the opportunity to endorse or not endorse our fiscal 2015 executive compensation programs and policies and the compensation paid to our Named Executive Officers for the fiscal year ended December 31, 2015.

As described under the heading “Compensation Overview,” our executive compensation programs are designed to attract, motivate, and retain our Named Executive Officers, who are critical to our success. Under these programs, our Named Executive Officers are rewarded for the achievement of annual, long-term and strategic goals, and corporate goals. The Compensation Committee, which is comprised of independent directors, continually reviews the compensation programs for our Named Executive Officers to ensure they achieve the desired goals of aligning our executive compensation structure with our shareholders’ interests and current market practices.

This vote is not intended to address any specific item of compensation, but rather the overall compensation of our Named Executive Officers and the philosophy, policies and practices described in this Proxy Statement. Accordingly, we will ask our shareholders to vote “FOR” the following resolution at the 2016 Annual Meeting:

“RESOLVED, that the Company’s shareholders approve, on an advisory basis, the compensation of the Named Executive Officers, as disclosed in the Company’s Proxy Statement for the 2016 Annual Meeting of Shareholders pursuant to the compensation disclosure rules of the Securities and Exchange Commission.”

The say-on-pay vote is advisory, and therefore not binding on the Company, the Compensation Committee or our Board of Directors. Our Board of Directors and our Compensation Committee value the opinions of our shareholders and to the extent there is any significant vote against the Named Executive Officers’ compensation as disclosed in this Proxy Statement, we will consider our shareholders’ concerns and the Compensation Committee will evaluate whether any actions are necessary to address those concerns.

The Board of Directors recommends a vote “FOR” the approval of the compensation of our Named Executive Officers.

18

PROPOSAL 4

RATIFICATION OF INDEPENDENT AUDITORS

The Audit Committee selected MaloneBailey, LLPWolf & Company, P.C. as an independent registered public accounting firm to audit our financial statements for the year ending December 31, 20162018, and requestsour Board has directed that the shareholders ratify such selection. In the event the shareholders fail to ratify the appointment, the Audit Committee of the Board will consider it as a direction to select other auditors for the subsequent year. Even ifmanagement submit the selection is ratified, the Board at its discretion may direct the appointment of a differentour independent registered public accounting firm for ratification by our shareholders at any time during the subsequent year if the Board determines that such a change would be in the best interests of Opexa and our shareholders.

We are asking shareholders to ratify the selection of MaloneBailey, LLPAnnual Meeting. Wolf & Company, P.C. has acted as our independent auditorsregistered public accounting firm since September 20, 2017 and audited our financial statements for the fiscal year endingended December 31, 2016. 2017. Wolf & Company, P.C. served as the independent registered public accounting firm to Private Acer prior to the merger. Prior to September 20, 2017, MaloneBailey, LLP served as our independent registered public account firm.

A representative of MaloneBailey, LLPWolf & Company, P.C. is expected to be present at the Annual Meeting, will have an opportunity to make a statement if the representative desires but is not expected to do so, and is expected to be available to respond to appropriate questions. We do not expect a representative of MaloneBailey, LLP, our former independent registered public accounting firm, to be present at the Annual Meeting.

Neither our bylaws nor other governing documents or law require shareholder ratification of the selection of Wolf & Company, P.C. as our independent registered public accounting firm. However, we are submitting the selection of Wolf & Company, P.C. to the shareholders for ratification as a matter of good corporate practice. If our shareholders fail to ratify the selection, our Audit Committee will reconsider whether or not to retain that firm. Even if the selection is ratified, our Audit Committee in its discretion may direct the appointment of different independent auditors at any time during the year if they determine that such a change would be in the best interests of Acer and our shareholders.

Audit Fees

The following table presents (i) the estimated aggregate fees billed to us for the fiscal years ended December 31, 2017 and 2016 by MaloneBailey, LLP, who served as our independent registered public accounting firm during the period of January 1, 2016 to September 20, 2017, and (ii) the aggregate fees billed to us for services performed duringthe fiscal years ended December 31, 2017 and 2016 by Wolf & Company, P.C., who was appointed as our last two fiscal years.independent registered public accounting firm on September 20, 2017.

Change in Independent Registered Public Accounting Firm

On September 20, 2017, we engaged Wolf & Company, P.C., as our independent registered public accounting firm to audit our financial statements for the fiscal year ended December 31, 2017, and we dismissed MaloneBailey, LLP. Prior to the completion of the merger, Wolf & Company, P.C. served as the auditor and independent registered public accounting firm to Private Acer. The decision to change accountants was approved by the Audit Committee of our Board of Directors.

The report of MaloneBailey, LLP on our consolidated financial statements for the year ended December 31, 2016 did not contain an adverse opinion or disclaimer of opinion, nor was it qualified or modified as to uncertainty, audit scope, or accounting principles, except that our financial statements for the fiscal year ended December 31, 2016 expressed, in an explanatory paragraph, substantial doubt about our ability to continue as a going concern due to recurring losses, negative operating cash flows and an accumulated deficit.

During the years ended December 31, 2017 and 2016, there were no: (1) disagreements (as defined in Item 304(a)(1)(iv) of RegulationS-K and the related instructions) with MaloneBailey, LLP on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedures, which disagreement if not resolved to the satisfaction of MaloneBailey, LLP would have caused MaloneBailey, LLP to make reference thereto in its reports, or (2) reportable events (as described in Item 304(a)(1)(v) of RegulationS-K).

During the years ended December 31, 2017 and 2016, neither we nor anyone on our behalf consulted with Wolf & Company, P.C. regarding either (i) the application of accounting principles to a specific transaction, completed or proposed, or the type of audit opinion that might be rendered on our financial statements, and neither a written report nor oral advice was provided to us that Wolf & Company, P.C. concluded was an important factor considered by us in reaching a decision as to any accounting, auditing or financial reporting issue or (ii) any matter that was either the subject of a disagreement (as defined in Item 304(a)(1)(iv) of RegulationS-K and the related instructions) or a reportable event (as described in Item 304(a)(1)(v) of RegulationS-K).

Policy on Audit CommitteePre-Approval and PermissibleNon-Audit Services of Independent Auditors

The Board’s policy is topre-approve all audit and permissiblenon-audit services provided by the independent auditors. These services may include audit services, audit-related services, tax services and other services.Pre-approval is generally provided for up to one year and anypre-approval is detailed as to the particular service or category of services and is generally subject to a specific budget. The independent auditors and management are required to periodically report to the Board regarding the extent of services provided by the independent auditors in accordance with thispre-approval, and the fees for the services performed to date. The Board may alsopre-approve particular services on acase-by-case basis. The Audit Committeepre-approved 100% of theany audit-related services, tax services andor other services provided by our independent auditors during the last two fiscal years.

The Board of Directors recommends a voteTHE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” the ratification of the selection of MaloneBailey, LLP as our independent auditors for the fiscal year ending December 31, 2016.THE RATIFICATION OF THE SELECTION OF WOLF & COMPANY, P.C. AS OUR INDEPENDENT AUDITORS

EXECUTIVE OFFICERS

Our executive officers are elected by the Board of Directors and serve at the discretion of the Board. Our current executive officers are as follows:

Biographical information for our executive officers is set forth below:

Neil K. WarmaChris Schelling has served as President and Chief Executive Officer since June 2008 and as a Director since September 2008. He has also served as Acting Chief Financial Officer since March 2016, and previously served as our Acting Chief Financial Officer from March 2009 to August 2012. From July 2004 to September 2007, Mr. Warma served as president and chief executive officer of Viron Therapeutics Inc., a privately-held clinical stage biopharmaceutical company. From 2000 to 2003 Mr. Warma was co-founder and president of MedExact USA, Inc., an Internet company providing clinical information and services to physicians and pharmaceutical companies. From 1992 to 2000, Mr. Warma held senior positions of increasing responsibility at Novartis Pharmaceuticals (previously Ciba-Geigy Ltd.) at its corporate headquarters in Basel, Switzerland. While at Novartis, Mr. Warma served as the Head of International Pharma Policy & Advocacy and in senior management within global marketing where he worked on the international launch of a gastrointestinal product. Mr. Warma obtained an honors degree specializing in Neuroscience from the University of Toronto and an International M.B.A. from the Schulich School of Management at York University in Toronto. As our President and Chief Executive Officer and as a Director since the completion of the merger in September 2017. Mr. Warma is directly involvedSchelling founded Private Acer in all aspectsDecember 2013 and has served as a director since that time. From December 2013 to February 2016, he served as Private Acer’s chief operating officer, and since February 2016 has served as Private Acer’s president and chief executive officer. Mr. Schelling also founded Apanii Consulting, LLC, a pharmaceutical and biotechnology consulting company, in December 2012 and currently serves as Apanii’s chief executive officer. Prior to founding Apanii Consulting, he served as executive director of our operations.strategic marketing at BioMarin Pharmaceutical Inc., or BioMarin, a Nasdaq-listed biotechnology company, from May 2006 to October 2012. He has extensive experiencealso held roles at Abgenix, Inc., Cell Therapeutics, Inc., Stanford Research Institute Consulting and Organon. Mr. Schelling earned a B.A. in corporate business development within the biopharmaceutical industry, in addition to executive leadership and management experience.biology from Carroll College.

Don Healey, Ph.D.William T. Andrews, M.D., FACPhas served as our Chief ScientificMedical Officer since April 2013. Dr. Healey has over 25 years of experience in cellular immunology and immune regulation in both academic and biotech environments.October 2017. Prior to joining OpexaAcer, Dr. Andrews provided strategic consulting services to rare disease companies from April 2016 to September 2017. Prior to that, he served Aegerion Pharmaceuticals, Inc., a biopharmaceutical company, as senior vice president, business development, from May 2014 to January 2016, and as vice president of medical affairs, from April 2012 to May 2014. He has also held roles at Santhera Pharmaceuticals, Sepracor, Inc. and ClinQuest, Inc. Prior to joining the biopharmaceutical industry over 15 years ago, Dr. Andrews practiced medicine for seven years full-time and 11 years part-time in April 2010, Dr. Healey was Director of Immunology for Argos Therapeutics from 2003 to 2010,the Boston area as a board certified internist and an attending physician at Brigham and Women’s Hospital, and was responsible foron the developmentclinical faculty at Harvard Medical School. Dr. Andrews earned a B.A. in biology from Harvard University and a Ph.D. from Yale University School of novel autologous dendritic cell therapies for the treatment of renal carcinoma and HIV. Dr. Healey was Group Leader for Immunotherapy for ML Laboratories, UK (formerly Cobra Biotherapeutics) from 2001 to 2003, where he developed autologous dendritic cell therapies for the treatment of Melanoma. Dr. Healey was a member of Council of the British Society for Immunology from 1996 to 1998. He is a former lecturer in immunology at the University of Leicester, UK, and held post-doctoral positions in the Department of Pathology, Cambridge University, UK, conducting studies on immunoregulation in animal models of autoimmunity, including Type I Diabetes and Multiple Sclerosis. Dr. Healey obtained his Ph.D. at the Hunterian Institute in London, UK, and BSc in the Department of Pathology, Bristol University, UK.Medicine.

Donna R. RillHarry S. Palmin was appointedhas served as our Chief DevelopmentFinancial Officer since the completion of the merger in AprilSeptember 2017. From December 2013 to February 2016, Mr. Palmin served as the president, chief executive officer and a director of Private Acer, from February 2016 to September 2017 he served as Private Acer’s acting chief financial officer, and he currently serves as the chief financial officer of Private Acer. Prior to joining Private Acer, he served in a variety of roles at Novelos Therapeutics, Inc., a pharmaceutical company, including as president and director from 1998 to October 2013, chief executive officer from January 2005 to October 2013 and previously served as Senior Vice President of Operationsacting chief financial officer from 1998 to September 2005. He has also held roles at Lehman Brothers and Quality Systems since January 2009. From November 2004 until January 2009, she served as Vice President of Operations. From April 2003 to November 2004, she was the director of quality systemsMorgan Stanley. Mr. Palmin earned a B.A. in economics from Brandeis University and process development at Opexa Pharmaceuticals, Inc. From November 1997 to April 2003, she was the director of translational research for the Center for Cell & Gene Therapy at Baylor College of Medicine. Ms. Rill has worked to designa M.A. in international economics and qualify GMP Cell & Gene Therapy Laboratories, GMP Vector Production facilities, and Translational Research Labs at St. Jude Children’s Research Hospital, Texas Children’s Hospital, and Baylor College of Medicine. Ms. Rill received her B.S. in Medical Technologyfinance from the Brandeis University of Tennessee, Memphis.International Business School.

EXECUTIVE COMPENSATION AND OTHER INFORMATION

Compensation Overview

Objectives of Our Executive Compensation Program

The Compensation Committee of our Board administers our executive compensation program. The Compensation Committee is composed entirely of independent directors.

The general philosophy of our executive compensation program is to align executive compensation with Opexa’s business objectives and the long-term interests of our shareholders. To that end, the Compensation Committee believes executive compensation packages we provide to our executives, including the Named Executive Officers, should include both cash and stock-based compensation that reward performance as measured against established goals. In addition, we strive to provide compensation that is competitive with other biopharmaceutical and biotechnology companies and that will allow us to attract, motivate, and retain qualified executives with superior talent and abilities.

Our executive compensation is designed to reward achievement of our corporate goals. In 2015, our corporate goals included, but were not limited to: (i) advancing our phase 2b clinical trial of Tcelna in patients with SPMS; (ii) obtaining additional financing to support our operations, including our phase 2b clinical trial of Tcelna in patients with SPMS; (iii) continuing the expansion of our T-cell technology platform through preclinical development of OPX-212 in neuromyelitis optica; and (iv) various corporate governance objectives. We believe that the focus of our executives on the achievement of corporate goals allows us to reward our executives for their roles in creating value for our shareholders.

Compensation Committee Processes and Procedures

The Compensation Committee has the primary authority to determine our compensation philosophy and to establish compensation for our executive officers. The Compensation Committee oversees our compensation and benefit plans and policies; administers our stock option plan; reviews the compensation components provided to our officers, employees, and consultants; grants options to purchase common stock to our officers, employees, and consultants; and reviews and makes recommendations to the Board regarding all forms of compensation to be provided to the members of the Board.

The Compensation Committee generally sets the initial compensation of each executive. The Compensation Committee annually reviews and in some cases adjusts compensation for executives. Although the Chief Executive Officer provides recommendations to the Compensation Committee regarding the compensation of the other executive officers, the Compensation Committee has full authority over all compensation matters relating to executive officers.

In establishing compensation amounts for our executives and independent directors, the Compensation Committee seeks to provide compensation that is competitive in light of current market conditions and industry practices. Accordingly, the Compensation Committee annually reviews market data which is comprised of proxy-disclosed data from peer companies and information from nationally recognized published surveys for the biopharmaceutical industry, adjusted for size. The market data helps the Committee gain perspective on the compensation levels and practices at peer companies and assess the relative competitiveness of the compensation paid to our executives and independent directors. The market data thus guides the Compensation Committee in its efforts to set executive compensation at competitive levels for comparable roles in the marketplace. The Compensation Committee then takes into account other factors, such as the importance of each executive officer’s role to the Company, individual expertise, experience, and performance, retention concerns and relevant compensation trends in the marketplace, in making its final compensation determinations.

Role of Compensation Consultant

From time to time and as it determines necessary or desirable, the Compensation Committee may retain the services of an independent compensation consultant to advise on compensation-related matters relating to the executive officers and independent directors. The Compensation Committee did not engage a consultant for compensation-related matters in 2015.

Elements of Executive Compensation

Although the Compensation Committee has not adopted any formal guidelines for allocating total compensation between equity compensation and cash compensation, it strives to maintain a strong link between executive incentives and the creation of shareholder value. Therefore, we emphasize incentive compensation in the form of stock options rather than base salary.

21

Executive compensation consists of the following elements:

Base Salary. Base salaries for our executives are generally established based on the scope of their responsibilities, taking into account what the Compensation Committee believes to be, based on its general business experience, competitive market compensation paid by other companies for similar positions and recognizing cost of living considerations. Prior to making its recommendations and determinations, the Compensation Committee reviews each executive’s:

The Compensation Committee does not use any particular indices or formulae to arrive at each executive’s recommended pay level. Evaluations of past performance are made on a strictly qualitative basis, and may include such factors as leadership performance, contribution to the officer group, overall performance, continuous improvements, and other appropriate measures. In making decisions as to the base salaries of our executive officers, the Compensation Committee does not engage in benchmarking by using specific compensation data about other companies as a reference point.

Annual Cash Incentive Bonus. As described below under “Executive Employment Agreements,” each of the employment agreements we have entered into with our Named Executive Officers provides the officer with the opportunity to earn a cash bonus up to a stated percentage of his or her base salary based upon objectives and milestones to be agreed upon annually by our Board and Chief Executive Officer. The Board retains discretion, however, to pay a portion of any such bonus in the form of equity (including grants of restricted stock).

Equity Awards. We also use long-term incentives in the form of stock options and restricted stock awards. Employees and executive officers generally receive stock option grants at the commencement of employment and periodically receive additional stock option grants or restricted stock awards, typically on an annual basis. We believe that stock options and restricted stock awards incentivize executive performance and are instrumental in aligning the long-term interests of our employees and executive officers with those of the shareholders because such individuals realize gains based on the value of the underlying shares and stock price increases. Equity awards also help to balance the overall executive compensation program, with base salary and cash bonuses providing short-term compensation and stock options and restricted stock awards rewarding executives for long-term increases in shareholder value.

Options and restricted stock awards are granted through our 2010 Stock Incentive Plan. The Compensation Committee reviews and approves equity awards to executive officers in amounts that are based upon a review and assessment of:

Periodic equity awards are made at the discretion of the Compensation Committee to eligible employees and, in appropriate circumstances, the Compensation Committee considers the recommendations of members of management, such as the Chief Executive Officer. In determining the amount of any equity award, the Compensation Committee gives subjective consideration to our Named Executive Officers’ contributions towards the achievement of our goals.

In 2015, each Named Executive Officer was granted stock options in the amount indicated in the table entitled “2015 Outstanding Equity Awards at Fiscal Year-End.” Stock options are granted with an exercise price equal to the fair market value of our common stock on the day of grant and recent option grants generally vest 25% after one year with the remaining 75% vesting quarterly over the next three years. The grant date fair value of these equity awards is computed in accordance with FASB ASC 718, and such grant date fair value is included in the total compensation of each of the Named Executive Officers. See Note 10 to our financial statements included in our Annual Report on Form 10-K for assumptions underlying the valuation of equity awards.

Pursuant to the terms of our 2010 Stock Incentive Plan, in 2015 the Compensation Committee recommended that a pool of shares of common stock be available at the discretion of the Chief Executive Officer to grant stock options to non-executive employees, and the Board approved such delegation of authority. The purpose of this delegation of authority is to enhance the flexibility of option administration and to facilitate the timely grant of options to non-management employees.

Severance Arrangements. As described below under “Executive Employment Agreements,” each of the employment agreements we have entered into with our Named Executive Officers provides the officer with certain severance protection arrangements in the event the officer’s employment is terminated by the Board without cause. In such event, the officer will receive a

22

severance payment equal to a stated number of months of base salary, subject to certain conditions and the execution and delivery of a general release and waiver of claims in our favor. We believe the provisions of these severance arrangements are consistent with the principal objectives of our compensation programs, appropriate for the level of service provided by each executive, and provide an important “safety net” that allows each executive to focus on our business and pursue the course of action that is in the best interests of our shareholders by alleviating some potential concerns regarding their personal financial well-being in the event of a termination.

Section 162(m) Policy

Section 162(m) of the Code limits the tax deductibility by public companies of compensation in excess of $1 million paid to certain executive officers. These officers include any employee who, as of the close of the taxable year, is the principal executive officer, and any employee whose total compensation for the taxable year is required to be reported to shareholders under the Exchange Act by reason of such employee being among the three highest compensated officers for that taxable year, other than the principal executive officer or the principal financial officer. However, compensation which qualifies as “performance-based” is excluded from the $1 million limit if, among other requirements, the compensation is payable only upon attainment of pre-established, objective performance goals under a plan approved by the corporation’s shareholders.

It is our policy to qualify, to the extent reasonable, our executive officers’ compensation for deductibility under applicable tax law. However, we intend to retain the flexibility necessary to provide total cash compensation in line with competitive practice, our compensation philosophy and our best interests. Therefore, we may from time to time pay compensation to our executive officers that may not be deductible.

Executive Officer Compensation

The following table sets forth certain information concerning compensation earned by or paid to certain persons who we refer to as our “Named Executive Officers” for services provided for the fiscal year ended December 31, 2015.2017. Our Named Executive Officers include persons who (i) served as our principal executive officer or acted in a similar capacity during 2015,2017, (ii) were serving at fiscalyear-end as our two most highly compensated executive officers, other than the principal executive officer, whose total compensation exceeded $100,000, and (iii) if applicable, up to two additional individuals for whom disclosure would have been provided as a most highly compensated executive officer, but for the fact that the individual was not serving as an executive officer at fiscalyear-end.

20152017 Summary Compensation Table

23

Executive Employment AgreementsNarrative Disclosure to Summary Compensation Table

Acer’s Board of Directors reviews compensation annually for all of its executive officers. Compensation awarded to Named Executive Officers in 2017 generally consisted of base salary and equity awards for options to purchase shares of Acer’s common stock. In setting executive compensation, Acer’s Board of Directors considered compensation for comparable positions in the market, the historical compensation levels of its executives, individual performance as compared to its expectations and objectives, the desire to motivate employees to achieve short- and long-term results that are in the best interests of our shareholders, and a long-term commitment to Acer. Acer does not target a specific competitive position or a specific mix of compensation among elements of compensation. Prior to the September 2017 merger with Opexa, Private Acer retained the services of Radford (which is a part of Aon Hewitt, a business unit of Aon plc) as an independent compensation consultant to (i) evaluate Private Acer’s executive compensation program and recommend a course of action for consideration in preparation for becoming a public company and (ii) assess Private Acer’snon-employee director compensation practices against a selection of peer group companies and make a recommendation relating thereto. Subsequent to closing of the merger with Opexa in September 2017, our Compensation Committee reviewed the analysis and reports prepared by Radford and provided to Private Acer and implemented certain compensation adjustments for our executives andnon-employee directors. In reviewing the reports prepared by Radford for Private Acer, our Compensation Committee considered the independence of Radford pursuant to SEC rules and the corporate governance rules of The Nasdaq Stock Market and concluded that no conflict of interest exists that would prevent Radford from independently advising the Compensation Committee. During the last fiscal year, the Compensation Committee engaged in discussions without formally meeting, to build a consensus on various related matters, and all formal actions were taken by the Board of Directors.

Neil K. WarmaAgreement with Former Opexa Executive Officer. We entered intoPrior to the merger, Mr. Warma was employed by Opexa as President, Chief Executive Officer and Acting Chief Financial Officer pursuant to the terms of an employment agreement ondated June 16, 2008 with Neil K. Warma pursuant2008. Upon effectiveness of the merger on September 19, 2017, which was deemed to which he serves as our President and Chief Executive Officer. Pursuant to thebe a change of control under his employment agreement, which automatically renews for 12-month periods, Mr. Warma is currently compensatedWarma’s employment was terminated. Mr. Warma’s base salary at the ratetime of his termination was $416,625 per annum. In addition, Mr. Warma is entitledannum, and he was eligible to the following: (i)receive an annual discretionary cash bonus of up to 50% of his base salary based upon milestoneson the achievement of selected objectives. Pursuant to be agreed upon; and (ii) a one-time payment of $50,000 cash and 781shares of our common stock to be issued if and when the closing bid price of our common stock equals or exceeds $128.00 for 20 consecutive trading days. In addition, we provide Mr. Warma with our standard benefits and insurance coverage as generally provided to our management, as well as contractual indemnification rights by reasonterms of his service as an officer and employee. If his employment is terminated by the Board without cause, as defined in the agreement, Mr. Warma will be entitled to receive ahe received lump sum severance paymentcompensation equal to 1218 months of his base salary plusand a payment equal to 30%45% of his base salary in lieu of any potential bonus, in addition any earned but unpaid bonus. In addition, vestingHe is also entitled to receive reimbursement of stock options will accelerate in full. We will also reimburse Mr. Warma for COBRA expenses for a 12-monthan18-month period, subject to a cap equal to Opexa’s standard contribution to employee health benefits. Upon the effectiveness of a change in control, as defined in the agreement, Mr. Warma will receive 18 months of salary and COBRA reimbursement and a payment equal to 45% of base salary in lieu of any potential bonus, in addition to any earned but unpaid bonus. In addition, allthe vesting of Mr. Warma’s stock options will accelerateaccelerated in full. Any payment or benefit Mr. Warma might receive upon a change of control which would constitute a “parachute payment”full, although all such options were under Section 280G ofwater and were cancelled in connection with the Internal Revenue Code will be reduced so as not to trigger excise tax under Section 4999 of such Code.merger. Mr. Warma’s agreement also provides that for a12-month period following his termination of employment, he will not engage or participate in any competitive business or solicit or recruit any of ourthe Company’s employees. The severance and change of control benefits are subject to Mr. Warma executing and delivering a general release and waiver of claims in favor of Opexa.

Don Healey, Ph.D. We entered into an employment agreement with Don Healey on March 4, 2010, pursuant to which Mr. Healey serves as our Chief Scientific Officer. Mr. Healey is currently compensated at the rate of $270,000 per annum and is eligible to receive an annual discretionary bonus of up to 35% of his base salary per 12-month period, based on the achievement of objectives as determined by Opexa’s Board and Chief Executive Officer. In addition, Mr. Healey receives our standard benefits and insurance coverage as generally provided to our management, as well as contractual indemnification rights by reason of his service as an officer and employee. Mr. Healey’s employment may be terminated at any time voluntarily by him or without cause (as defined in the agreement) by the Board. If his employment is terminated by the Board without cause, Mr. Healey will be entitled to receive a severance payment equal to six months of his base salary. The severance benefits are subject to Mr. Healey having been continuously employed through the termination event, executing and delivering a general release and waiver of claims in favor of Opexa, not being in breach of the employment agreement or Opexa’s proprietary information and inventions agreement, and not engaging in any activity which is competitive with Opexa during the term of the employment agreement or while receiving the severance benefits. The timing of any payments to Mr. Healey under the employment agreement is subject to applicable requirements of Section 409A of the Code and the related Treasury Regulations.

Karthik Radhakrishnan. Mr. Radhakrishnan was employed as our Chief Financial Officer from March 29, 2013 until his employment terminated on March 2, 2016 as part of a restructuring initiative and reduction-in-force which occurred on that date. Pursuant to the terms of his March 2013 offer letter, he will be entitled to receive severance payments equal to six months of his base salary and vesting for any unvested stock options will accelerate by six additional months. In addition, Mr. Radhakrishnan will have a period of 12 months following his termination of employment within which to exercise any vested options, as opposed to the three months otherwise available for terminating employees. The severance benefits are subject to Mr. Radhakrishnan executing and deliveringdelivered a general release and waiver of claims in favor of the Company not being in breach of the offer letter or the Company’s proprietary information and inventions agreement, and not engaging in any activity which is competitive with the Company while receiving theconsideration for his severance benefits. Mr. Radhakrishnan’s salary at the time of his termination was $275,000 per annum. The timing of any payments to Mr. Radhakrishnan is subject to applicable requirements of Section 409A of the Code and the related Treasury Regulations.compensation.

20152017 Outstanding Equity Awards at FiscalYear-End

The following table presents information regarding outstanding equity awards at December 31, 20152017 for each of the Named Executive Officers.

25

Certain Relationships and Related Party Transactions

Transactions with Related Persons

Since January 1, 2015,2017, we have engaged in no reportable transactions with our directors, executive officers, beneficial holders of more than 5% of our voting securities, and affiliates or their immediate family members.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

Beneficial Ownership

The following table sets forth, as of March 31, 2016,1, 2018, the number and percentage of outstanding shares of our common stock beneficially owned by: (a) each person who is known by us to be the beneficial owner of more than 5% of our outstanding shares of common stock; (b) each of our directors;directors and nominees; (c) the Named Executive Officers; and (d) all current directors and executive officers as a group. As of March 31, 2016,1, 2018, there were 6,982,9097,497,433 shares of common stock issued and outstanding.

Beneficial ownership has been determined in accordance with Rule13d-3 under the Exchange Act. Under this rule, certain shares may be deemed to be beneficially owned by more than one person (if, for example, persons share the power to vote or the power to dispose of the shares). In addition, shares are deemed to be beneficially owned by a person if the person has the right to acquire shares (for example, upon exercise of an option or warrant) within 60 days of the date as of which the information is provided. In computing the percentage ownership of any person, the amount of shares is deemed to include the amount of shares beneficially owned by such person by reason of such acquisition rights. As a result, the percentage of outstanding shares of any person as shown in the following table does not necessarily reflect the person’s actual voting power at any particular date.

To our knowledge, except as indicated in the footnotes to this table and pursuant to applicable community property laws, the persons named in the table have sole voting and investment power with respect to all shares of common stock shown as beneficially owned by them.

Beneficial Ownership Table

26

Section 16(a) Beneficial Ownership Reporting Compliance

Section 16(a) of the Exchange Act requires our directors and executive officers, and persons who beneficially own more than 10% of a registered class of our equity securities, to file with the SEC initial reports of ownership and reports of changes in ownership. These reporting persons are required by SEC regulations to furnish us with copies of all such reports they file. To our knowledge, based solely on our review of the copies of such reports furnished to us and written representations from certain insiders that no other reports were required, we believe all of the reporting persons complied with all applicable Section 16(a) filing requirements applicable to them with respect to transactions during the fiscal year ended December 31, 2015.2017, except that one group Form 4 was filed late by funds affiliated with TVM Capital Life Science and Drs. Birner and Marengere to report the purchase of common stock by TVM Capital Life Science funds in our December 2017 underwritten public offering.

27

HOUSEHOLDING

The SEC has adopted rules that permit companies and intermediaries (e.g., brokers) to satisfy the delivery requirements for proxy statements and annual reports with respect to two or more shareholders sharing the same address by delivering a single proxy statement addressed to those shareholders. This process, which is commonly referred to as “householding,” potentially means extra convenience for shareholders and cost savings for companies.

A number of brokers with account holders who are our shareholders may be “householding” our proxy materials. If householding is in effect, a single proxy statement will be delivered to multiple shareholders sharing an address unless contrary instructions have been received from the affected shareholders. Once you have received notice from your broker that they will be “householding” communications to your address, “householding” will continue until you are notified otherwise or until you revoke your consent. If, at any time, you no longer wish to participate in “householding” and would prefer to receive a separate copy of the proxy statement and annual report, please notify your broker. Shareholders who currently receive multiple copies of the proxy statement and/or annual report at their address and would like to request “householding” of their communications should contact their broker. We will deliver a separate set of proxy materials promptly upon written or oral request from a shareholder. Please direct any such requests to Investor Relations, OpexaAcer Therapeutics Inc., 2635 Technology Forest Blvd.One Gateway Center, Suite 351 (300 Washington Street), The Woodlands, Texas 77381,Newton, Massachusetts 02458, or call Investor Relations at (281) 272-9331.(844)902-6100.

OTHER BUSINESS

The Board knows of no other business to come before the Annual Meeting. However, if any other matters are properly brought before the Annual Meeting, the person named in the accompanying form of proxy or his or their substitutes will vote in their discretion on those matters.

By Order of the Board of Directors

Neil K. WarmaChris Schelling

President and Chief Executive Officer

April 11, 20169, 2018

The Woodlands, TexasNewton, Massachusetts

WHETHER OR NOT YOU PLAN TO ATTEND THE ANNUAL MEETING, PLEASE COMPLETE, SIGN, DATE, AND PROMPTLY RETURN THE ACCOMPANYING PROXY IN THE ENCLOSED ENVELOPE OR USE ONE OF THE VOTING METHODS DESCRIBED IN THE ATTACHED MATERIALS. YOU MAY REVOKE YOUR PROXY AT ANY TIME PRIOR TO THE ANNUAL MEETING. IF YOU DECIDE TO ATTEND THE ANNUAL MEETING AND WISH TO CHANGE YOUR PROXY VOTE, YOU MAY DO SO AUTOMATICALLY BY VOTING IN PERSON AT THE MEETING. IF YOUR SHARES ARE HELD OF RECORD BY A BROKER, BANK OR OTHER NOMINEE AND YOU WISH TO ATTEND AND VOTE IN PERSON AT THE MEETING, YOU MUST OBTAIN FROM THE RECORD HOLDER A LEGAL PROXY ISSUED IN YOUR NAME.

THANK YOU FOR YOUR ATTENTION TO THIS MATTER. YOUR PROMPT RESPONSE WILL GREATLY

FACILITATE ARRANGEMENTS FOR THE ANNUAL MEETING.

If you need additional copies of this Proxy Statement or the enclosed proxy card, or if you have other questions about the proposals or how to vote your shares, you may contact our proxy solicitor:

ADVANTAGE PROXY

(877)870-8565 (toll free)

Appendix A

PLAN OF CONVERSION

OF

ACER THERAPEUTICS INC.,

A TEXAS CORPORATION

TO

ACER REINCORPORATION, INC.,

A DELAWARE CORPORATION

This Plan of Conversion (the “Plan of Conversion”) is adopted as of this [            ] day of [            ], 2018, by Acer Therapeutics Inc., a Texas corporation (the “Company”), to effect its conversion into Acer Reincorporation, Inc., a Delaware corporation (the “Converted Company”).

WHEREAS, the Company is a corporation duly organized and existing under the laws of the State of Texas;

WHEREAS, the Company’s directors deem it advisable and in the best interest of the Company and its shareholders to convert to a corporation duly organized and existing under the laws of the State of Delaware (the “Conversion”), pursuant to the terms, provisions and conditions set forth in this Plan of Conversion and in accordance with Sections 10.101 and 10.103 of the Texas Business Organizations Code (the “TBOC”) and Section 265 of the Delaware General Corporation Law (the “DGCL”); and

WHEREAS, the Company’s board of directors has authorized, approved and adopted the form, terms and provisions of this Plan of Conversion and submitted this Plan of Conversion to the Company’s shareholders for approval, and the Company’s shareholders have approved this Plan of Conversion.

NOW THEREFORE, in consideration of the foregoing, the conversion will take place pursuant to the following terms and conditions:

1.Conversion; Effect of Conversion.

a. At the Effective Time (as hereinafter defined), the Company will be converted into the Converted Company, pursuant to, and in accordance with, Sections 10.101 and 10.103 of the TBOC, and Section 265 of the DGCL, whereupon the previous organizational form of the Company will cease, and the Company will continue its existence in the organizational form of the Converted Company, which will be subject to the laws of the State of Delaware.

b. At the Effective Time, by virtue of the Conversion and without any further action on the part of the Company or its shareholders, the Converted Company shall, for all purposes of the laws of the State of Texas and the State of Delaware, be deemed to be the same entity as the Company. At the Effective Time, by virtue of the Conversion and without any further action on the part of the Company or its shareholders, for all purposes of the laws of the State of Delaware, all of the rights, privileges and powers of the Company, and all property, real, personal and mixed, and all debts due to the Company, as well as all other things and causes of action belonging to the Company, shall remain vested in the Converted Company and shall be the property of Converted Company and the title to any real property vested by deed or otherwise in the Company shall not revert or be in any way impaired by reason of the Conversion; but all rights of creditors and all liens upon any property of the Company shall be preserved unimpaired, and all debts, liabilities and duties of the Company shall remain attached to the Converted Company at the Effective Time, and may be enforced against the Converted Company to the same

extent as if said debts, liabilities and duties had originally been incurred or contracted by the Converted Company in its capacity as a corporation of the State of Delaware. The rights, privileges, powers and interests in property of the Company, as well as the debts, liabilities and duties of the Company, shall not be deemed, as a consequence of the Conversion, to have been transferred to the Converted Company at the Effective Time for any purpose of the laws of the State of Delaware.

c. The Company shall not be required to wind up its affairs or pay its liabilities and distribute its assets, and the Conversion shall not be deemed to constitute a dissolution of the Company and shall constitute a continuation of the existence of the Company in the form of a Delaware corporation. The Converted Company is the same entity as the Company. The Conversion shall not be deemed to affect any obligations or liabilities of the Company incurred prior to the Conversion or the personal liability of any person incurred prior to the Conversion.

d. At the Effective Time, the name of the Converted Company shall be: Acer Reincorporation, Inc.

e. The Company intends for the Conversion to constitute a reorganization within the meaning of Section 368(a) of the Internal Revenue Code, as amended.

2.Filings. As promptly as practicable following the date hereof, the Company shall cause the Conversion to be effective by:

a. executing and filing (or causing to be executed and filed) a Certificate of Conversion pursuant to Section 10.154 of the TBOC substantially in the form set forth onExhibit A hereto with the Secretary of State of the State of Texas;

b. executing and filing (or causing to be executed and filed) a Certificate of Conversion pursuant to Section 265 of the DGCL substantially in the form set forth onExhibit B hereto (the “Delaware Certificate of Conversion”) with the Secretary of State of the State of Delaware (the “Delaware Secretary of State”); and

c. executing, acknowledging and filing (or causing to be executed, acknowledged and filed) a Certificate of Incorporation of Acer Reincorporation, Inc. substantially in the form set forth onExhibit C hereto (the “Delaware Charter”) with the Delaware Secretary of State.

3.Effective Time. The Conversion shall become effective upon the filing with the Delaware Secretary of State of the Delaware Certificate of Conversion (the time of the effectiveness of the Conversion, the “Effective Time”).

4.Conversion of Shares of Common Stock. At the Effective Time, each share of common stock in the Company, par value $0.01 per share (the “Company Common Stock”), issued and outstanding immediately prior to the Effective Time shall automatically, by virtue of the Conversion and without any further action on the part of the Company or any other person or entity, be converted into one share of the Converted Company, par value $0.0001 per share (the “Converted Company Common Stock”).

5.Effect of Conversion on Outstanding Stock Options, Warrants and Other Rights to Acquire Shares of Common Stock. At the Effective Time, each option, warrant and other right to acquire shares of Company Common Stock outstanding immediately prior to the Effective Time shall automatically, by virtue of the Conversion and without any further action on the part of the Company or any other person or entity, be converted into an equivalent option, warrant or other right to acquire, as applicable, upon the same terms and conditions (including the exercise price per share applicable to each such option, warrant or other right to acquire) as were in effect immediately prior to the Effective Time, the same number of shares of Converted Company Common Stock.

6.Effect of Conversion on Stock Certificates. At the Effective Time, all of the outstanding certificates that immediately prior to the Effective Time represented shares of Company Common Stock immediately prior to the Effective Time shall automatically, by virtue of the Conversion and without any further action on the part of the Company or any other person or entity, be deemed for all purposes to continue to evidence ownership of and to represent the same number of shares of Converted Company Common Stock into which the shares represented by such certificates have been converted as provided herein. The registered owner on the books and records of the Converted Company or its transfer agent of any such outstanding stock certificate shall, until such certificate shall have been surrendered for transfer or conversion or otherwise accounted for to the Converted Company or its transfer agent, have and be entitled to exercise any voting and other rights with respect to and to receive any dividend and other distributions upon the shares of the Converted Company evidenced by such outstanding certificate as provided above.

7.Effect of Conversion on Employee Benefit, Incentive Compensation or Other Similar Plans. At the Effective Time, each employee benefit plan, incentive compensation plan or other similar plan to which the Company is a party shall automatically, by virtue of the Conversion and without any further action on the part of the Company or any other person or entity, continue to be a plan of the Converted Company. To the extent that any such plan provides for the issuance of Company Common Stock, at the Effective Time, such plan shall be deemed to provide for the issuance of Converted Company Common Stock. A number of shares of Converted Company Common Stock shall be reserved for issuance under such plan or plans equal to the number of shares of Company Common Stock so reserved immediately prior to the Effective Time.

8.Filings, Licenses, Permits, Titled Property, Etc. As necessary, following the Effective Time, the Converted Company shall apply for new qualifications to conduct business (including as a foreign corporation), licenses, permits and similar authorizations on its behalf and in its own name in connection with the Conversion and to reflect the fact that it is a corporation duly formed and validly existing under the laws of the State of Delaware. As required or appropriate, following the Effective Time, all real, personal or intangible property of the Company which was titled or registered in the name of the Company shall bere-titled orre-registered, as applicable, in the name of the Converted Company by appropriate filings or notices to the appropriate party (including, without limitation, any applicable governmental agencies).

9.Further Assurances. If, at any time after the Effective Time, the Converted Company shall determine or be advised that any deeds, bills of sale, assignments, agreements, documents or assurances or any other acts or things are necessary, desirable or proper, consistent with the terms of this Plan of Conversion, (a) to vest, perfect or confirm, of record or otherwise, in the Converted Company its right, title or interest in, to or under any of the rights, privileges, immunities, powers, purposes, franchises, properties or assets of the Company, or (b) to otherwise carry out the purposes of this Plan of Conversion, the Converted Company, its officers and directors and the designees of its officers and directors, are hereby authorized to solicit in the name of the Converted Company any third-party consents or other documents required to be delivered by any third-party, to execute and deliver, in the name and on behalf of the Converted Company all such deeds, bills of sale, assignments, agreements, documents and assurances and do, in the name and on behalf of the Converted Company, all such other acts and things necessary, desirable or proper to vest, perfect or confirm its right, title or interest in, to or under any of the rights, privileges, immunities, powers, purposes, franchises, properties or assets of the Company and otherwise to carry out the purposes of this Plan of Conversion.

10.Effect of Conversion on Directors and Officers. The members of the board of directors and the officers of the Company immediately prior to the Effective Time shall continue in office following the Effective Time as the directors and officers of the Converted Company, respectively, until the expiration of their respective terms of office and until their successors have been duly elected and have qualified, or until their earlier death, resignation or removal. After the Effective Time, the Converted Company and its board of directors shall take any necessary actions to cause each of such individuals to be appointed or to confirm such appointments.

11.Delaware Bylaws. At the Effective Time, the Bylaws of the Converted Company (the “Delaware Bylaws”), a copy of which are attached hereto asExhibit D, shall govern the Converted Company until amended in accordance with the Delaware Bylaws, the Delaware Charter or applicable law.

12.Delaware Indemnification Agreements. As promptly as practicable following the Effective Time, the Converted Company shall enter into an Indemnification Agreement substantially in the form set forth onExhibit E hereto with each member of the board of directors of the Converted Company and each officer of the Converted Company.

13.Office. From and after the Effective Time, the Company’s principal office shall be the same as that of the Company’s principal office, which is as follows: One Gateway Center, Suite 351 (300 Washington St.), Newton, Massachusetts 02458.

14.Registered Office and Agent. From and after the Effective Time, the Converted Company’s initial registered agent and registered office shall be: The Corporation Trust Company, 1209 Orange Street, Wilmington, County of New Castle, Delaware 19801.

15.Shareholder Approval. This Plan of Conversion was recommended by the Company’s directors and submitted to and approved by the Company’s shareholders as required by the Company’s Restated Certificate of Formation, as amended, and Amended and Restated Bylaws, as amended, and in accordance with the TBOC. All required documents shall be executed, filed and recorded and all required acts shall be done to accomplish the Conversion contemplated hereby required by law.

16.Implementation and Interpretation. This Plan of Conversion shall be implemented and interpreted, prior to the Effective Time, by the board of directors of the Company and, upon the Effective Time, by the board of directors of the Converted Company, (a) each of which shall have full power and authority to delegate and assign any matters covered hereunder to any other party(ies), including, without limitation, any officers of the Company or the Converted Company, as the case may be, and (b) the interpretations and decisions of which shall be final, binding and conclusive on all parties.

17.Termination; Abandonment. At any time prior to the Effective Time, the consummation of the Conversion may be deferred for a reasonable period of time if, in the opinion of the board of directors of the Company, such action would be in the best interest of the Company and its shareholders. This Plan of Conversion may be terminated and/or the Conversion abandoned at any time prior to the Effective Time by the action of the board of directors of the Company, notwithstanding the approval of this Plan of Conversion by the shareholders of the Company. In the event of termination of this Plan of Conversion and/or abandonment of the Conversion, then this Plan of Conversion shall become void and of no further force and effect without liability on the part of any party hereto or their respective officers and agents.

[Signature Page Follows]

IN WITNESS WHEREOF, the Company has caused this Plan of Conversion to be duly executed effective as of the date and year first written above.

28

AppendixExhibit A

OPEXATexas Certificate of Conversion

[Texas Certificate of Conversion in the form of Appendix B to this Proxy Statement attached.]

Exhibit B

Delaware Certificate of Conversion

[Delaware Certificate of Conversion in the form of Appendix C to this Proxy Statement attached.]

Exhibit C

Delaware Charter

[Delaware Charter in the form of Appendix D to this Proxy Statement attached.]

Exhibit D

Delaware Bylaws

[Delaware Bylaws in the form of Appendix E to this Proxy Statement attached.]

Exhibit E

Delaware Indemnification Agreement

[Delaware Indemnification Agreement in the form of Appendix F to this Proxy Statement attached.]

Appendix B

CERTIFICATE OF CONVERSION

OF

A TEXAS CORPORATION

TO

A DELAWARE CORPORATION

(In compliance with Section 10.154 of the

Business Organizations Code of the State of Texas)

Converting Entity Information

Converted Entity Information

Plan of Conversion

Approval of the Plan of Conversion

Effectiveness of Filing

Tax Certificate

Execution

The undersigned signs this document subject to the penalties imposed by law for the submission of a materially false or fraudulent instrument. The undersigned certifies that the statements contained herein are true and correct, and the person signing is authorized under the provisions of the Business Organizations Code of the State of Texas to execute the filing instrument.

Appendix C