X0306 4 2022-03-04 0 0001382101 SUTRO BIOPHARMA, INC. STRO 0001309660 NEWELL WILLIAM J C/O SUTRO BIOPHARMA, INC. 111 OYSTER POINT BLVD. SOUTH SAN FRANCISCO CA 94080 1 1 0 0 CEO Common Stock 2022-03-05 4 M 0 18750 A 119943 D Common Stock 2022-03-05 4 F 0 6483 8.17 D 113460 D Common Stock 10577 I By Newell Family Revocable Trust DTD 08/14/2008 Common Stock 106525 I By William J. Newell Family Trust DTD 03/15/2019 Stock Option (right to buy Common Stock) 8.17 2022-03-04 4 A 0 166000 0.00 A 2032-03-03 Common Stock 166000 166000 D Restricted Stock Unit (RSU) 2022-03-04 4 A 0 124500 0.00 A 2026-03-04 Common Stock 124500 124500 D Restricted Stock Unit (RSU) 2022-03-05 4 M 0 18750 0.00 D 2025-03-05 Common Stock 18750 56250 D Each RSU represents a contingent right to receive one (1) share of the issuer's Common Stock upon settlement. Represents the number of shares of Common Stock that have been withheld by the issuer to satisfy its income tax withholding and remittance obligations in connection with the net settlement of the RSUs and does not represent a sale by the reporting person. The securities are held of record by the reporting person as trustee of the Newell Family Revocable Trust DTD 08/14/2008. The securities are held of record by the reporting person as trustee of the William J. Newell Family Trust DTD 03/15/2019. The option vests as to 2.0833% of the total shares monthly, beginning on April 4, 2022, with 100% of the total shares vested and exercisable on March 4, 2026, subject to the reporting person's provision of service to the issuer on each vesting date. The RSUs vest as to 1/4th of the total shares annually beginning on March 4, 2023, subject to continued service through each vesting date. The RSUs vest as to 1/4th of the total shares annually beginning on March 5, 2022, subject to continued service through each vesting date. /s/ Edward C. Albini as attorney-in-fact for William J. Newell 2022-03-07