X0306 4 2017-09-19 0001069308 Acer Therapeutics Inc. ACER 0001221599 ASELAGE STEVE 222 THIRD STREET SUITE #2240 CAMBRIDGE MA 02142 true Common Stock 2017-09-19 4 J false 11905 A 11905 D Nonqualified Stock Option (right to buy) 2.55 2017-09-19 4 J false 21000 A 2025-10-19 Common Stock 21000 21000 D Received in connection with the Issuer's business combination (the "Merger") with what was then known as "Acer Therapeutics Inc." ("Private Acer") in accordance with the terms of the Agreement and Plan of Merger and Reorganization dated June 30, 2017 among the Issuer, Opexa Merger Sub, Inc. and Private Acer, in exchange for 11,905 shares of common stock of Private Acer. Received in connection with the Merger in exchange for an option to acquire 21,000 shares of common stock of Private Acer. Option vests in eight equal quarterly installments beginning on October 19, 2015. /s/ Daniel S. Clevenger, Attorney-in-Fact for Steve Aselage 2017-09-21