UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

Commission File Number: 001-36812

31 St. James Avenue, 6 ^th  Floor

Boston, MA 02116

(617) 874-1821

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant's Principal Executive Offices)

William McVicar, Ph.D.

President and Chief Executive Officer

Flex Pharma, Inc.

31 St. James Avenue, 6 ^th  Floor

Boston, MA 02116

(617) 874-1821

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

Securities registered pursuant to Section 12(b) of the Act

Securities registered pursuant to Section 12(g) of the Act:  None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes   o No ý

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Act. Yes   o No ý

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to the filing requirements for the past 90 days. Yes   ý No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).  Yes   ý No   o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§ 229.405) is not contained herein, and will not be contained, to the best of the registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.      ý

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of large accelerated filer, accelerated filer, smaller reporting company, and emerging growth company in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.      ý

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act.) Yes   o No   ý

       As of June 30, 2018, the last day of the registrant’s most recently completed second fiscal quarter, the aggregate market value of the Common Stock held by non-affiliates of the registrant was approximately $9.8 million, based on the closing price of the registrant’s common stock on June 29, 2018.

As of April 2, 2019, there were 18,069,476 shares of common stock outstanding.

EXPLANATORY NOTE  

Flex Pharma, Inc., sometimes referred to as "we," "our" or the "Company," is filing this Amendment No. 1 on Form 10-K/A, or this Amendment, to its Annual Report on Form 10-K for the year ended December 31, 2018, originally filed on March 6, 2019, or the Original Report, for the sole purpose of including the information required by Part III of Form 10-K. This information was previously omitted from the Original Report in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above referenced items to be incorporated in the Form 10-K by reference from our definitive proxy statement if such statement is filed no later than 120 days after the our fiscal year-end. We are filing this Amendment to provide information required in Part III of Form 10-K because a definitive proxy statement containing such information will not be filed by the Company within 120 days after the end of the fiscal year covered by the Form 10-K.

        In accordance with Rule 12b-15 under the Securities and Exchange Act of 1934, as amended, or the Exchange Act, Part III, Items 10 through 14 of the Original Report are hereby amended and restated in their entirety, and Part IV, Item 15 of the Original Report is hereby amended and restated in its entirety, with the only changes being the addition of the new certifications by our principal executive officer and principal financial officer filed herewith. This Amendment does not amend or otherwise update any other information in the Original Report. Accordingly, this Amendment should be read in conjunction with the Original Report and with our filings with the Securities and Exchange Commission subsequent to the Original Report.

TABLE OF CONTENTS

Item 10. Directors, Executive Officers and Corporate Governance

Information About Our Board of Directors

The Company's Board of Directors, or the Board, presently has six members and two vacancies. Robert Perez, Christoph Westphal and Roderick MacKinnon resigned from the Board effective January 31, 2018, March 7, 2018 and July 23, 2018, respectively. Jeffrey D. Capello retired from our Board at the 2018 annual meeting of stockholders. Neither Mr. Capello's retirement nor Mr. Perez's, Dr. Westphal's or Dr. MacKinnon's resignation were the result of any disagreements with the Company and were a result of their desires to pursue other interests.

Set forth below are the names, ages and lengths of service of the members of our Board. There are no family relationships among any of our executive officers or directors.

The biography of each of the directors below contains information regarding the person's business experience, director positions held currently or at any time during the last five years, and the experiences, qualifications, attributes and skills that caused the nominating and corporate governance committee and our Board to determine that the person should serve as a director, given our business and structure.

William K. McVicar, Ph.D ., has served as a member of the Board of Directors since August 2017. Dr. McVicar has served as our Chief Executive Officer since July 2017. Dr. McVicar joined the Company in April 2017 as our President of Research & Development. Prior to joining the Company, Dr. McVicar served as Executive Vice President of Pharmaceutical Development, Chief Scientific Officer and President during his tenure at Inotek Pharmaceuticals Corporation from September 2007 to April 2017. Dr. McVicar also held various positions at Sepracor, Inc., RPR Gencell, the Gene and Cell Therapy Division of Rhone Poulenc Rorer, and Novartis AG. Dr. McVicar earned his B.S. in Chemistry from the State University of New York College at Oneonta and his Ph.D. in Chemistry from the University of Vermont. We believe that Dr. McVicar is qualified to serve on our Board of Directors due to his over 30 years of biologic and drug development experience and his experience as a senior executive.

Stuart Randle , has served as a member of the Board of Directors since October 2014. Mr. Randle served as the Chief Executive Officer of Ivenix, Inc. from December 2015 to December 2018. Previously, Mr. Randle served as the Chief Executive Officer of GI Dynamics, Inc. from 2004 through September 2014. Prior to GI Dynamics, Mr. Randle served as the President and Chief Executive Officer of ACT Medical, Inc. from 1998 to 2001. Prior to 1998, Mr. Randle was Corporate Vice President and responsible for the northeastern region of the United States for Allegiance Healthcare Corporation. Mr. Randle previously worked for Baxter Healthcare Corporation in various roles including President, New England region, General Manager of anesthesia, and various sales and marketing roles. Mr. Randle has also held various sales and engineering roles with Ingersoll-Rand Corporation. Mr. Randle is a member of the Board of Directors of Teleflex, Inc. and Beacon Roofing Supply, Inc. and previously served as a member of the Board of Directors of Ivenix, Inc. and GI Dynamics, Inc. Mr. Randle earned an M.B.A. from The Kellogg Graduate School of Management at Northwestern University and a B.S. degree in Mechanical Engineering from Cornell University. We believe that Mr. Randle is qualified to serve on our Board of Directors due to his over 20 years of experience in the life sciences industry in engineering, sales,

marketing, senior management and leadership roles in developing companies and divisions of major medical corporations.

Marc Kozin has served as a member of the Board of Directors since October 2014. Mr. Kozin was a Senior Advisor to L.E.K. Consulting, a global strategy consulting firm from July 2011 to December 2018. Prior to that, Mr. Kozin served as President of L.E.K.'s North American practice for 15 years. Mr. Kozin currently serves as a member of the Board of Directors of Dicerna Pharmaceuticals, Inc. and UFP Technologies, Inc. and he previously served on the Board of Directors of DYAX Corp., Endocyte, Inc. and OvaScience, Inc. He also serves on the strategic advisory board for Healthcare Royalty Partners. Mr. Kozin holds a B.A., with distinction, in Economics from Duke University and an M.B.A., with distinction, from The Wharton School, University of Pennsylvania. We believe that Mr. Kozin is qualified to serve on our Board of Directors due to his nearly 30 years of experience in corporate and business unit strategy consulting, merger and acquisition advisory services, and value management, both domestically and internationally.

Dr. Roger Tung, Ph.D. , has served as a member of the Board of Directors since October 2017. Dr. Tung is the co-founder, President and Chief Executive Officer of Concert Pharmaceuticals, Inc. (“Concert”). Before Concert, Dr. Tung was a founding scientist at Vertex Pharmaceuticals Incorporated (“Vertex”), a pharmaceutical company, where he was employed from 1989 to 2005, most recently as its Vice President of Drug Discovery. Prior to Vertex, he held various positions at Merck, Sharp & Dohme Research Laboratories, a global healthcare provider, and The Squibb Institute for Medicinal Chemistry. Dr. Tung is a member of the board of directors of Concert. Dr. Tung received a B.A. in Chemistry from Reed College and a Ph.D. in medicinal chemistry at the University of Wisconsin-Madison. We believe that Dr. Tung is qualified to serve on our Board of Directors due to his over 30 year career in the global pharmaceutical and biotechnology industries, including his roles at Concert and Vertex.

Michelle Stacy , has served as a member of the Board of Directors since March 2016. As the former president of Keurig, Inc. and former vice president and general manager with Gillette/P&G, Ms. Stacy brings to the Board of Directors experience leading consumer businesses and global brands. Ms. Stacy currently sits on the Board of Directors of iRobot Corporation, Coravin, Inc. and The HydraFacial Company. Previously, Ms. Stacy sat on the Board of Directors of Young Innovations, Inc. and Tervis Tumbler Company, and also served as a Director Advisor to The Cambridge Group (an AC Nielson Company). Ms. Stacy is a professional speaker on leadership, innovation and growth. She received a M.S. in Management from J. L. Kellogg Graduate School of Management - Northwestern University, and a B.S. from Dartmouth College. We believe that Ms. Stacy is qualified to serve on our Board of Directors given her broad marketing, senior management and leadership roles in consumer companies.

Peter Barton Hutt, L.L.B., L.L.M. , has been a member of the Board of Directors since March 2014. Mr. Hutt is a senior counsel at the law firm of Covington & Burling LLP and has been an attorney with that firm since 1960. He served as Chief Counsel for the U.S. Food and Drug Administration from 1971 through 1975. Mr. Hutt is a member of the National Academy of Medicine of the National Academy of Sciences and teaches a course on Food and Drug Law each winter term at Harvard Law School. He co-authored the casebook used to teach Food and Drug Law and has published numerous papers on the subject. Mr. Hutt is a member of the Board of Directors of Q Therapeutics, Moderna, Inc., Immunomedics, Inc. and Concert Pharmaceuticals Inc., and several privately-held life sciences companies. During the last five years, Mr. Hutt has also served as a member of the Board of Directors of BIND Therapeutics, Inc., Celera Genomics, DBV Technologies, Momenta Pharmaceuticals, Inc. and Ista Pharmaceuticals, Inc. Mr. Hutt received his B.A., magna cum laude, from Yale University, his L.L.B. from Harvard University and his L.L.M. from New York University. We believe that Mr. Hutt is qualified to serve on our Board of Directors due to his 50 years of experience and expertise in food and drug regulation, including his service at the U.S. Food and Drug Administration and at Covington & Burling LLP, and his experience serving on other boards of directors in the biotechnology industry .

John McCabe has served as our Chief Financial Officer since December 2016. From May 2014 to December 2016, Mr. McCabe served as our Vice President, Finance. Mr. McCabe joined us from ARIAD Pharmaceuticals, Inc. where he was Vice President and Chief Accounting Officer from May 2013 to May 2014. Previously, Mr. McCabe served as Vice President and Corporate Controller at Charles River Associates from June 2009 to May 2013. Previously, Mr. McCabe was the Director, Strategic Business Unit Controller at Biogen, Inc. from 2007 until 2009. Mr. McCabe has also held positions at Performance Technologies, Inc., IP.com Inc. and Arthur Andersen LLP. Mr. McCabe earned an M.B.A. from the University of Massachusetts at Amherst and B.S. degrees in Accounting and Management Information Systems from Babson College.

Thomas Wessel, M.D., Ph.D. , served as our Chief Medical Officer from December 2014 to June 2018. Dr. Wessel's position was eliminated in June 2018 in connection with our corporate restructuring and strategic assessment. Prior to joining us, Dr. Wessel was an independent consultant to several biotechnology and large pharmaceutical companies. Previously, Dr. Wessel was the Chief Medical Officer of Acorda Therapeutics, Inc. from November 2008 until September 2011. Between March 2002 and October 2008, Dr. Wessel was employed in various leadership positions at Sepracor, Inc., including Senior Vice President of Clinical Research. Before joining Sepracor, Dr. Wessel worked on several CNS projects at Janssen Pharmaceuticals. Before working in the pharmaceutical industry, Dr. Wessel held several academic and research positions. Dr. Wessel received his M.D. from the University of Munich School of Medicine and completed his Ph.D. in experimental neurobiology at the Max-Planck-Institute for Psychiatry in Martinsried, Germany. He completed his residency in neurology at New York Hospital and Memorial Sloan-Kettering Cancer Center (Cornell University Medical Center).

Audit Committee

Prior to Mr. Capello's retirement from the Board, the Audit Committee consisted of Messrs. Capello and Kozin and Ms. Stacy. Upon Mr. Capello's resignation, Mr. Hutt joined the Audit Committee and Ms. Stacy assumed the role of Audit Committee chair. The Board of Directors has determined that each of the members of the Audit Committee satisfies the Nasdaq Stock Market and SEC independence requirements. The Board of Directors determined that Mr. Capello, through the date of his retirement, and Ms. Stacy, upon assuming the role of Audit Committee chair, both qualify as an audit committee financial expert within the meaning of SEC regulations and meet the financial sophistication requirements of the Nasdaq Listing Rules. The Audit Committee is governed by a written audit committee charter that is available to shareholders on our website at www.flex-pharma.com. The inclusion of our website address here and elsewhere in this amendment does not include or incorporate by reference the information on our website into this amendment.

Code of Ethics

We have adopted a code of business conduct and ethics that applies to all of our employees, officers and directors, including those officers responsible for financial reporting. Our code of business conduct and ethics is available on our website at www.flex-pharma.com. We intend to disclose any amendments to the code, or any waivers of its requirements, on our website.

Section 16(a) Beneficial Ownership Reporting Compliance

Section 16(a) of the Exchange Act requires our directors and executive officers, and persons who own more than ten percent of a registered class of our equity securities, to file with the SEC initial reports of ownership and reports of changes in ownership of common stock and other equity securities of the Company. Officers, directors and greater than 10% shareholders are required by SEC regulation to furnish us with copies of all Section 16(a) forms they file.

Based solely on a review of the copies of such reports furnished to us and written representations that no other reports were required, we believe that, during the fiscal year ended December 31, 2018, all of our officers, directors and greater than 10% beneficial owners complied with all Section 16(a) filing requirements applicable to them.