X0306 4 2021-11-23 0 0001290149 Sierra Oncology, Inc. SRRA 0001363558 Collard Craig A C/O SIERRA ONCOLOGY, INC. 1820 GATEWAY DRIVE, SUITE 110 SAN MATEO CA 94404 1 0 0 0 Common Stock 2021-11-23 4 P 0 5601 22.945 A 5601 D Common Stock 2021-11-24 4 P 0 7899 23.085 A 13500 D The "Amount" and "Price" reported in this Column 4 reflect the aggregate number and weighted-average price, respectively, of shares purchased. These shares were purchased in multiple transactions at prices ranging from $22.625 to $23.00, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the SEC staff, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth herein. The "Amount" and "Price" reported in this Column 4 reflect the aggregate number and weighted-average price, respectively, of shares purchased. These shares were purchased in multiple transactions at prices ranging from $22.645 to $23.10, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the SEC staff, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth herein. /s/ Craig A. Collard; By: Mary Christina Thomson, Attorney-In-Fact 2021-11-24