Author: Editor

NEWTON, MA, January 31, 2018 – Acer Therapeutics Inc. (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced that Chris Schelling, CEO and Founder, will provide a corporate overview at the LEERINK Partners 7th Annual Global Healthcare Conference, being held February 14-15, 2018 in New York.

Acer Therapeutics Conference Presentation Details

Date: Thursday, February 15

Time: 3:30 pm Eastern Time

Location: Lotte New York Palace, Hubbard I, 5th Floor

Webcast:https://www.acertx.com/investor-relations/events-presentations/

About Acer Therapeutics

Acer, headquartered in Newton, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vascular Ehlers-Danlos syndrome (vEDS), and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s product candidates have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and potential approval of a marketing application. For more information, visit www.www.acertx.com.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 617-535-7743

[email protected]

NEWTON, MA, January 3, 2018 – Acer Therapeutics Inc. (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced that Chris Schelling, CEO and Founder, will provide a corporate overview at the Biotech Showcase™ Conference, being held January 8-10, 2018 in San Francisco.

Acer Therapeutics Conference Presentation Details

Date: Wednesday, January 10

Time: 1:30 pm Eastern Time (10:30 am Pacific Time)

Location: Hilton Union Square, Yosemite -B

Webcast: https://www.acertx.com/investor-relations/events-presentations/

About Acer Therapeutics

Acer, headquartered in Newton, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully tastemasked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s product candidates have clinical proof-ofconcept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and potential approval of a marketing application. For more information, visit www.www.acertx.com.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 617-535-7743

[email protected]

NEWTON, MA – Dec. 27, 2017 – Acer Therapeutics Inc. (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced that the underwriters of its previously announced public offering of common stock have partially exercised their over-allotment option by the purchase of an additional 130,000 shares at a price to the public of $12.00 per share, resulting in additional gross proceeds of $1.56 million, before deducting underwriting discounts and commissions and other offering expenses payable by Acer. After giving effect to the partial exercise of the over-allotment option, the total number of shares sold by Acer in the offering increased to 1,046,667 shares and the total gross proceeds increased to $12.56 million. Acer intends to use the net proceeds from this offering to fund its research and development efforts, to seek regulatory approval for EDSIVO™, to invest in pre-commercial activities for EDSIVO™ and for general corporate purposes, including working capital and other general and administrative purposes. William Blair & Company, L.L.C. acted as sole book-running manager of the offering. H.C. Wainwright & Co. acted as lead manager of the offering. The shares of common stock described above were offered by Acer pursuant to its shelf registration statement on Form S-3 previously filed and declared effective by the Securities and Exchange Commission. The offering was made only by means of a prospectus supplement and an accompanying prospectus. Copies of the final prospectus supplement and the accompanying prospectus may be obtained from William Blair & Company, L.L.C., Attention: Prospectus Department, 150 North Riverside Plaza, Chicago, IL 60606; Telephone: (800) 621-0687 or by email at [email protected]. This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Acer Therapeutics Acer, headquartered in Newton, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s product candidates have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and potential approval of a marketing application. For more information, visit www.www.acertx.com.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to the expected use of the net proceeds from the offering, and the development and future potential of Acer’s product candidates. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward-looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with market conditions, unexpected cash requirements, changes in Acer’s business plan, and the process of developing, obtaining regulatory approval for and commercializing drug candidates that are safe and effective for use as human therapeutics. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made. You should review additional disclosures we make in our filings with the Securities and Exchange Commission, including our Quarterly Reports on Form 10-Q and Annual Report on Form 10-K and the Registration Statement on Form S-3 (File No. 333-208314) for the public offering. You may access these documents for no charge at http://www.sec.gov.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 617-535-7743

[email protected]

NEWTON, MA – Dec. 14, 2017 – Acer Therapeutics Inc. (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced the closing of the previously announced underwritten public offering of 916,667 shares of its common stock at a price to the public of $12.00 per share. The gross proceeds to Acer from this offering were $11.0 million, before deducting the underwriting discount and other estimated offering expenses. All of the shares in the offering were sold by Acer. In addition, Acer has granted the underwriters a 30-day option to purchase up to an additional 137,500 shares of common stock. Acer intends to use the net proceeds from this offering to fund its research and development efforts, to seek regulatory approval for EDSIVO™, to invest in pre-commercial activities for EDSIVO™ and for general corporate purposes, including working capital and other general and administrative purposes. William Blair & Company, L.L.C. acted as sole book-running manager of the offering. H.C. Wainwright & Co. acted as lead manager of the offering. The shares of common stock described above were offered by Acer pursuant to its shelf registration statement on Form S-3 previously filed and declared effective by the Securities and Exchange Commission. The offering was made only by means of a prospectus supplement and an accompanying prospectus. Copies of the final prospectus supplement and the accompanying prospectus may be obtained from William Blair & Company, L.L.C., Attention: Prospectus Department, 150 North Riverside Plaza, Chicago, IL 60606; Telephone: (800) 621-0687 or by email at [email protected]. This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Acer Therapeutics Acer, headquartered in Newton, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s product candidates have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and potential approval of a marketing application. For more information, visit www.www.acertx.com.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to the expected use of the net proceeds from the offering, and the development and future potential of Acer’s product candidates. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward-looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with market conditions, unexpected cash requirements, changes in Acer’s business plan, and the process of developing, obtaining regulatory approval for and commercializing drug candidates that are safe and effective for use as human therapeutics. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made. You should review additional disclosures we make in our filings with the Securities and Exchange Commission, including our Quarterly Reports on Form 10-Q and Annual Report on Form 10-K and the Registration Statement on Form S-3 (File No. 333-208314) for the public offering. You may access these documents for no charge at http://www.sec.gov.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 617-535-7743

[email protected]

NEWTON, MA – Dec. 14, 2017 – Acer Therapeutics Inc. (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced the closing of the previously announced underwritten public offering of 916,667 shares of its common stock at a price to the public of $12.00 per share. The gross proceeds to Acer from this offering were $11.0 million, before deducting the underwriting discount and other estimated offering expenses. All of the shares in the offering were sold by Acer. In addition, Acer has granted the underwriters a 30-day option to purchase up to an additional 137,500 shares of common stock. Acer intends to use the net proceeds from this offering to fund its research and development efforts, to seek regulatory approval for EDSIVO™, to invest in pre-commercial activities for EDSIVO™ and for general corporate purposes, including working capital and other general and administrative purposes. William Blair & Company, L.L.C. acted as sole book-running manager of the offering. H.C. Wainwright & Co. acted as lead manager of the offering. The shares of common stock described above were offered by Acer pursuant to its shelf registration statement on Form S-3 previously filed and declared effective by the Securities and Exchange Commission. The offering was made only by means of a prospectus supplement and an accompanying prospectus. Copies of the final prospectus supplement and the accompanying prospectus may be obtained from William Blair & Company, L.L.C., Attention: Prospectus Department, 150 North Riverside Plaza, Chicago, IL 60606; Telephone: (800) 621-0687 or by email at [email protected]. This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Acer Therapeutics Acer, headquartered in Newton, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s product candidates have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and potential approval of a marketing application.

For more information, visit www.www.acertx.com.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to the expected use of the net proceeds from the offering, and the development and future potential of Acer’s product candidates. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward-looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with market conditions, unexpected cash requirements, changes in Acer’s business plan, and the process of developing, obtaining regulatory approval for and commercializing drug candidates that are safe and effective for use as human therapeutics. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made. You should review additional disclosures we make in our filings with the Securities and Exchange Commission, including our Quarterly Reports on Form 10-Q and Annual Report on Form 10-K and the Registration Statement on Form S-3 (File No. 333-208314) for the public offering. You may access these documents for no charge at http://www.sec.gov.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 617-535-7743

[email protected]

NEWTON, MA – Dec. 11, 2017 – Acer Therapeutics Inc. (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced that it intends to offer and sell shares of its common stock, subject to market and other conditions, in an underwritten public offering. All shares being offered are to be sold by Acer. Acer intends to grant the underwriters a 30-day option to purchase an additional 15% of the shares of common stock offered in the public offering. Acer intends to use the net proceeds from this offering to fund its research and development efforts, to seek regulatory approval for EDSIVO™, to invest in pre-commercial activities for EDSIVO™ and for general corporate purposes, including working capital and other general and administrative purposes. William Blair & Company, L.L.C. is acting as sole book-running manager of the offering. The shares of common stock described above are being offered by Acer pursuant to its shelf registration statement on Form S-3 previously filed and declared effective by the Securities and Exchange Commission. The offering is being made only by means of a prospectus supplement and an accompanying prospectus. Copies of the preliminary prospectus supplement and the accompanying prospectus may be obtained from William Blair & Company, L.L.C., Attention: Prospectus Department, 150 North Riverside Plaza, Chicago, IL 60606; Telephone: (800) 621- 0687 or by email at [email protected]. This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Acer Therapeutics Acer, headquartered in Newton, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s product candidates have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and potential approval of a marketing application. For more information, visit www.www.acertx.com.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to the underwritten public offering, the expected use of the net proceeds from the offering, and the development and future potential of Acer’s product candidates. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with market conditions, the satisfaction of customary closing conditions related to the public offering, and the process of developing, obtaining regulatory approval for and commercializing drug candidates that are safe and effective for use as human therapeutics. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made. You should review additional disclosures we make in our filings with the Securities and Exchange Commission, including our Quarterly Reports on Form 10-Q and Annual Report on Form 10-K and the Registration Statement on Form S-3 (File No. 333-208314) for the public offering. You may access these documents for no charge at http://www.sec.gov.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 617-535-7743

[email protected]

Mr. Jason Amello and Ms. Michelle Griffin Join the Board

Acer Board Comprised of 7 Members

Cambridge, MA – October 12, 2017 Acer Therapeutics Inc., (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced the appointments of Mr. Jason Amello and Ms. Michelle Griffin to Acer’s Board of Directors. Mr. Amello and Ms. Griffin were appointed to the Audit Committee, with Ms. Griffin serving as Chairperson. “We are pleased to welcome Jason and Michelle as the newest members to our Board. Both bring decades of financial and commercial experience and public company operations expertise,” said Stephen Aselage, Chairman of the Board of Acer. “Their insight will add tremendous value to our Board, and we look forward to their contributions as we continue to execute on our development strategy and move towards filing of an NDA for our lead product candidate EDSIVO™.”

About Mr. Jason Amello Mr. Amello is the Senior Vice President, Chief Financial Officer, and Treasurer of Akebia Therapeutics, Inc. and has held the position since 2013. Prior to joining Akebia, Mr. Amello served as Executive Vice President, Chief Financial Officer, and Treasurer of ZIOPHARM Oncology, Inc. from 2012 to 2013. From 2000 to 2011, Mr. Amello held various positions at Genzyme Corporation, most recently as Senior Vice President, Corporate Controller, and Chief Accounting Officer, and led the Strategic Financial Services group through which he served as a key advisor on all of Genzyme’s M&A and strategic transactions. Earlier in his career, Mr. Amello spent 10 years in the business advisory and assurance practice of Deloitte, serving in various roles of increasing responsibility through senior manager. Mr. Amello currently serves on the Board of Directors of the New England Baptist Hospital, where he is the Chair of the Quality of Care Committee and a member of the Finance and Investment Committee. Mr. Amello holds a BA from Boston College and is a Certified Public Accountant in the Commonwealth of Massachusetts.

About Ms. Michelle Griffin Ms. Griffin currently provides consulting services to biotechnology companies and boards of directors through her firm, Pacific Biotechnology Consulting Group. Ms. Griffin currently serves on the board of directors and chair of the audit committee for PhaseRx, Inc. since February 2016 and as of August 2017 serves as chair of the board of directors for Universal Cells, Inc. Additionally, she serves on the board of directors of Virginia Mason Health System and Virginia Mason Medical Center. Ms. Griffin served as a member of the board of directors for Polynoma LLC from 2012 to 2014. She served as executive vice president, operations, and as chief financial officer at OncoGenex Pharmaceuticals Inc. from January 2011 to March 2013. Prior to that, Ms. Griffin served as a member of the board of directors of OncoGenex Pharmaceuticals Inc. from May 2004 to January 2011. She served as acting chief executive, senior vice president and chief operating officer at Trubion Pharmaceuticals, Inc., a biopharmaceutical company, from February 2006 until its acquisition in October 2010 by Emergent BioSolutions, Inc. From August 2005 to January 2006, Ms. Griffin served as senior vice president and chief financial officer of Dendreon Corporation, a biotechnology company. From March 1995 to July 2005, she was employed by Corixa Corporation, a biotechnology company, and served as its chief financial officer from 1997 until 2005 when Corixa Corporation was acquired by GlaxoSmithKline plc. Prior to that, Ms. Griffin held several finance and strategic planning positions at The Boeing Company. She received a post-graduate certificate in accounting and an MBA from Seattle University and a B.S. in statistics and marketing from George Mason University and has passed the certified public accountant exam.

About Acer Therapeutics Acer, headquartered in Cambridge, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s products have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and approval of a marketing application. For more information, visit www.www.acertx.com.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to the potential for EDSIVO™ (celiprolol) and ACER-001 to safely and effectively target diseases; the adequacy of the company’s capital to support its future operations and its ability to successfully initiate and complete clinical trials and regulatory submissions; the nature, strategy and focus of the company; and the development, expected timeline and commercial potential of any product candidates of the company. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward-looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with the ability to project future cash utilization and reserves needed for contingent future liabilities and business operations, the availability of sufficient resources of the company to meet its business objectives and operational requirements, the fact that the results of earlier studies and trials may not be predictive of future clinical trial results, the protection and market exclusivity provided by Acer’s intellectual property, risks related to the drug development and the regulatory approval process and the impact of competitive products and technological changes. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made. You should review additional disclosures we make in our filings with the Securities and Exchange Commission, including our Registration Statement on Form S-4 which was declared effective on August 10, 2017, and our Quarterly Reports on Form 10-Q and Annual Report on Form 10-K. You may access these documents for no charge at http://www.sec.gov.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 212-915-2568

[email protected]

Dr. Andrews’s Appointment Supports Acer’s Progression from Development to Potential Commercialization of Therapies

Cambridge, MA – October 5, 2017 Acer Therapeutics Inc., (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced the appointment of William T. Andrews, M.D., FACP as Chief Medical Officer of the Company to succeed Robert D. Steiner, M.D. in that position. “We are pleased to welcome Dr. Andrews to the executive management team, as we continue to successfully and rapidly advance our lead product candidate, EDSIVO™, a potential life-saving therapy for patients with vEDS,” said Chris Schelling, CEO and Founder of Acer. “Dr. Andrews brings tremendous experience to this role and will be instrumental in preparing our NDA submission of EDSIVO™, which we expect to accomplish in the first half of 2018, and we look forward to his guidance in the medical marketplace as we plan for our next steps. We thank Dr. Steiner for his significant contributions to Acer during a critical time in the Company’s growth.”

About William T. Andrews, M.D., FACP Dr. Andrews joins Acer Therapeutics as Chief Medical Officer after having worked in the biotech/pharmaceutical industry for 17 years in both Clinical Development and Medical Affairs in multiple therapeutic areas, with a focus and extensive experience in rare diseases. Dr. Andrews has significant medical marketplace and product launch experience, having served as the medical lead for six product launches, including Xopenex HFA, Brovana, Alvesco, Omnaris, Catena, and Juxtapid. Most recently, he provided strategic consulting services to rare disease companies in Clinical Development, Medical Affairs, Go-To-Market/Launch planning, and Business Development/Corporate Strategy. Previously, Dr. Andrews held senior leadership positions and positions of increasing responsibility at Aegerion Pharmaceuticals, Santhera Pharmaceuticals, Sepracor, and ClinQuest. He received his undergraduate degree in Biology from Harvard University and his M.D. degree from Yale University School of Medicine. Dr. Andrews practiced medicine for 7 years full-time and 11 years part-time in the Boston area as a board-certified Internist and an Attending Physician at Brigham and Women’s Hospital, and was on the Clinical Faculty at Harvard Medical School.

About Acer Therapeutics Acer, headquartered in Cambridge, MA, is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s products have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and approval of a marketing application. For more information, visit www.www.acertx.com.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to the potential for EDSIVO™ (celiprolol) and ACER-001 to safely and effectively target diseases; the adequacy of the company’s capital to support its future operations and its ability to successfully initiate and complete clinical trials and regulatory submissions; the nature, strategy and focus of the company; and the development, expected timeline and commercial potential of any product candidates of the company. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward-looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with the ability to project future cash utilization and reserves needed for contingent future liabilities and business operations, the availability of sufficient resources of the company to meet its business objectives and operational requirements, the fact that the results of earlier studies and trials may not be predictive of future clinical trial results, the protection and market exclusivity provided by Acer’s intellectual property, risks related to the drug development and the regulatory approval process and the impact of competitive products and technological changes. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made. You should review additional disclosures we make in our filings with the Securities and Exchange Commission, including our Quarterly Reports on Form 10-Q and our Annual Report on Form10-K. You may access these documents for no charge at http://www.sec.gov.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 212-915-2568

[email protected]

⦁ Company intends to file NDA for EDSIVO™ in first half of 2018     –

September 25, 2017

Cambridge, MA – Acer Therapeutics Inc., (Nasdaq: ACER), a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and ultra-rare diseases with critical unmet medical need, today announced positive results from the pivotal clinical trial of EDSIVO™ (celiprolol) for the treatment of vascular Ehlers-Danlos Syndrome (vEDS). Acer’s retrospective source verified analysis of the trial data, including the primary and secondary endpoints, confirmed the data from a previously published randomized controlled clinical study of celiprolol(1). Acer will use this pivotal clinical data to support a New Drug Application (NDA) regulatory filing in the U.S. in the first half of 2018. Ehlers-Danlos Syndrome (EDS) is a group of hereditary disorders of connective tissue. vEDS is the most severe subtype where patients suffer from life threatening arterial dissections and ruptures, as well as intestinal and uterine ruptures.  There are currently no FDA approved therapies for vEDS(2). “We have studied celiprolol for nearly two decades in vEDS patients and this is the only drug to ever demonstrate a clinical benefit in this difficult to treat patient population in a randomized, controlled clinical study,” said Pierre Boutouyrie M.D., Ph.D., co-director of the clinical pharmacology service at the Georges-Pompidou European Hospital, Greater Paris University Hospitals (AP-HP) and Principal Investigator for the published celiprolol study. “Having established celiprolol as the standard of care in France for vEDS patients, we are excited to collaborate with Acer to help bring celiprolol to U.S. patients who are suffering from this devastating, life-threatening disease.” The previously completed European study, published on October 30, 2010, in The Lancet, was stopped early having achieved statistical significance in its primary endpoints, with arterial dissection or rupture affecting 5 (20%) celiprolol patients and 14 (50%) subjects in the non-treated control group (hazard ratio [HR] 0.36; p-value 0.04). The combined primary and secondary endpoints of intestinal or uterine rupture affected 6 (24%) celiprolol patients and 17 (61%) subjects in the non-treated control group (HR 0.31; p-value 0.01). The study was conducted in 53 patients, who were randomly assigned either a twice daily treatment of celiprolol or no treatment.  Mean duration of follow-up was 47 months prior to trial halt. “We are committed to bringing EDSIVO™ to vEDS patients who currently do not have access to this treatment,” said Robert D. Steiner, M.D., Chief Medical Officer of Acer. “Our confirmation of the published celiprolol clinical data with an Acer-sponsored retrospective source verified analysis of the trial data represents a critical element of the clinical module in our NDA, which we are diligently building, along with current manufacturing, non-clinical and other components of the regulatory package.” “We continue to successfully rapidly advance our lead product candidate, EDSIVO™, a potential life-saving therapy for patients with vEDS, towards an NDA filing, which we expect to accomplish in the first half of 2018,” said Chris Schelling, CEO and Founder of Acer. “In addition to source verifying a definitive Event-Free Survival endpoint from a previously completed robust clinical study, modernizing manufacturing and assembling other components of the regulatory package, we are executing on a number of key medical affairs focused initiatives for vEDS patients.  Specifically, we are setting up Centers of Excellence to optimize patient care, and intend to develop a prospective vEDS Patient Registry and provide integrated care support programs.”

About EDSIVO™ and vEDS Ehlers-Danlos Syndrome (EDS) is a group of hereditary disorders of connective tissue. vEDS is the most severe subtype where patients suffer from life threatening arterial dissections and ruptures, as well as intestinal and uterine ruptures. The average mortality is 51 years of age. An Acer commissioned patient-finder study identified 2,200 vEDS patients in the U.S. from an analysis of commercially available patient claims data. However, experts estimate as many as 5,000 patients may be affected. There are currently no FDA-approved therapies for vEDS(2). Acer is advancing EDSIVO™ (celiprolol), a new chemical entity (NCE), for the treatment of vEDS and plans to file a NDA based on a randomized controlled clinical study of celiprolol.(1) In 2015, the U.S. Food and Drug Administration (FDA) granted EDSIVO™ orphan drug designation for the potential treatment of vEDS.

About Acer Therapeutics Acer, headquartered in Cambridge, MA, is a pharmaceutical company that acquires, develops and intends to commercialize therapies for patients with serious rare and ultra-rare diseases with critical unmet medical need. Acer’s late-stage clinical pipeline includes two candidates for severe genetic disorders for which there are few or no FDA-approved treatments: EDSIVO™ (celiprolol) for vEDS, and ACER-001 (a fully taste-masked, immediate release formulation of sodium phenylbutyrate) for urea cycle disorders (UCD) and Maple Syrup Urine Disease (MSUD). There are no FDA-approved drugs for vEDS and MSUD and limited options for UCD, which collectively impact more than 4,000 patients in the United States. Acer’s products have clinical proof-of-concept and mechanistic differentiation, and Acer intends to seek approval for them in the U.S. by using the regulatory pathway established under section 505(b)(2) of the Federal Food, Drug, and Cosmetic Act, or FFDCA, that allows an applicant to rely for approval at least in part on third-party data, which is expected to expedite the preparation, submission, and approval of a marketing application. For more information, visit www.www.acertx.com.

References

(1) Ong KT, et al. Effect of celiprolol on prevention of cardiovascular events in vascular Ehlers-Danlos syndrome: a prospective randomised, open, blinded-endpoints trial. Lancet. 2010; 376: 1476–84.

(2) Pepin MG, et al. Survival is affected by mutation type and molecular mechanism in vascular Ehlers–Danlos syndrome (EDS type IV) Genet Med. 16: 881-888.

Forward-Looking Statements This press release contains “forward-looking statements” that involve substantial risks and uncertainties for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995.  All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. Examples of such statements include, but are not limited to, statements relating to Acer’s listing on the Nasdaq Capital Market; expectations regarding the capitalization, resources and ownership structure of the company; the potential for EDSIVO™ (celiprolol) and ACER-001 to safely and effectively target diseases; the adequacy of the company’s capital to support its future operations and its ability to successfully initiate and complete clinical trials; the nature, strategy and focus of the company; the development and commercial potential of any product candidates of the company; and the executive and board structure of the company. Acer may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in the forward-looking statements and you should not place undue reliance on these forward-looking statements. Such statements are based on management’s current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, risks and uncertainties associated with the ability to project future cash utilization and reserves needed for contingent future liabilities and business operations, the availability of sufficient resources of the company to meet its business objectives and operational requirements, the fact that the results of earlier studies and trials may not be predictive of future clinical trial results, the protection and market exclusivity provided by Acer’s intellectual property, risks related to the drug development and the regulatory approval process and the impact of competitive products and technological changes. Acer disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made.

Investor Contact:

Hans Vitzthum

LifeSci Advisors

Ph: 212-915-2568

[email protected]