X0306 4 2022-07-01 1 0001290149 Sierra Oncology, Inc. SRRA 0001554591 Jagpal Sukhi C/O SIERRA ONCOLOGY, INC. 1820 GATEWAY DR., SUITE 110 SAN MATEO CA 94404 0 1 0 0 Chief Financial Officer Stock Option (right to buy) 122.20 2022-07-01 4 D 0 3859 0.00 D 2025-03-18 Common Stock 3859 0 D Stock Option (right to buy) 263.20 2022-07-01 4 D 0 1218 0.00 D 2026-03-08 Common Stock 1218 0 D Stock Option (right to buy) 72.80 2022-07-01 4 D 0 4200 0.00 D 2026-09-30 Common Stock 4200 0 D Stock Option (right to buy) 58.00 2022-07-01 4 D 0 1750 0.00 D 2027-03-06 Common Stock 1750 0 D Stock Option (right to buy) 94.40 2022-07-01 4 D 0 4509 0.00 D 2028-03-06 Common Stock 4509 0 D Stock Option (right to buy) 78.40 2022-07-01 4 D 0 5000 0.00 D 2029-03-04 Common Stock 5000 0 D Stock Option (right to buy) 13.31 2022-07-01 4 D 0 94113 0.00 D 2030-02-25 Common Stock 94113 0 D Stock Option (right to buy) 12.15 2022-07-01 4 D 0 49000 0.00 D 2030-08-12 Common Stock 49000 0 D Stock Option (right to buy) 12.15 2022-07-01 4 D 0 5887 0.00 D 2030-08-12 Common Stock 5887 0 D Stock Option (right to buy) 16.73 2022-07-01 4 D 0 30000 0.00 D 2031-03-15 Common Stock 30000 0 D Stock Option (right to buy) 31.54 2022-07-01 4 D 0 50000 0.00 D 2032-03-14 Common Stock 50000 0 D The option fully vested on February 2, 2019. Pursuant to the terms of the merger agreement between issuer, GlaxoSmithKline plc ("GSK") and a subsidiary of GSK, this option was cancelled on the effective date of the merger. The option fully vested on January 1, 2020. The option fully vested on September 30, 2019. The option fully vested on January 1, 2021. The option fully vested on January 1, 2022. The option vested as to 25% of the total shares on January 1, 2020, and then 2.0833% of the total shares vest monthly thereafter, with 100% of the total shares vested on January 1, 2023, subject to the reporting person's provision of service to the issuer on each vesting date. The option vested as to 25% of the total shares on February 25, 2021, and then 2.0833% of the total shares vest monthly thereafter, with 100% of the total shares vested on February 25, 2024, subject to the Reporting Person's provision of service to the Issuer on each vesting date. Pursuant to the terms of the merger agreement between issuer, GSK and a subsidiary of GSK, this option was cancelled on the effective date of the merger in exchange for a cash payment equal to, on a per share basis, the offer price of $55.00 less the exercise price. 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 option vested as to 25% of the total shares on August 10, 2021, and then 2.0833% of the total shares vest monthly thereafter, with 100% of the total shares vested on August 10, 2024, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The option vested as to 25% of the total shares subject to the option on March 15, 2022, and then 2.0833% of the shares subject to the option vest monthly thereafter, with 100% of the total shares subject to the option vested on March 15, 2025, subject to Reporting Person's provision of service to the Issuer on each vesting date. The option vests as to 25% of the total shares subject to the option on March 14, 2023, and then 2.0833% of the shares subject to the option vest monthly thereafter, with 100% of the total shares subject to the option vested on March 14, 2026, subject to Reporting Person's provision of service to the Issuer on each vesting date. /s/ Mary Christina Thomson, Attorney-In-Fact for Sukhi Jagpal 2022-07-01