X0306 4 2022-06-17 0 0001290149 Sierra Oncology, Inc. SRRA 0001295674 Thomson Mary Christina C/O SIERRA ONCOLOGY, INC. 1820 GATEWAY DRIVE, SUITE 110 SAN MATEO CA 94404 0 1 0 0 General Counsel, CCO & Sec'y Stock Option (Right to Buy) 12.15 2022-06-17 4 A 0 12250 0.00 A 2022-06-17 2030-08-12 Common Stock 12250 12250 D On August 12, 2020, the reporting person was granted an option to purchase 49,000 shares of common stock. The option vests based on the satisfaction by Issuer of certain performance criteria. The achievement of one of the performance criteria resulted in vesting of the option as to 12,250 shares. /s/ Mary Christina Thomson 2022-06-17