X0306 4 2017-09-19 0001069308 Acer Therapeutics Inc. ACER 0001717553 Steiner Robert D 222 THIRD STREET SUITE #2240 CAMBRIDGE MA 02142 true Chief Medical Officer Nonqualified Stock Option (right to buy) 2.55 2017-09-19 4 J false 40000 A 2026-04-05 Common Stock 40000 40000 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 an option to acquire 40,000 shares of common stock of Private Acer. Option vests in eight equal quarterly installments beginning on January 1, 2016. /s/ Daniel S. Clevenger, Attorney-in-Fact for Robert Steiner 2017-09-21