X0306 4 2019-09-26 0 0001382101 SUTRO BIOPHARMA, INC. STRO 0001398940 MOLINA ARTURO MD C/O SUTRO BIOPHARMA, INC. 310 UTAH AVENUE, SUITE 150 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Medical Officer Common Stock 2019-09-26 4 M 0 8608 0.00 A 8608 D Common Stock 2019-09-26 4 F 0 2976 9.74 D 5632 D Restricted Stock Unit (RSU) 2019-09-26 4 M 0 8608 0.00 D 2021-09-26 Common Stock 8608 17218 D 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. Each RSU represents a contingent right to receive one (1) share of the issuer's Common Stock upon settlement. The RSUs vest as to 1/3rd of the total shares annually beginning on September 26, 2019, subject to continued service through each vesting date. /s/ Edward C. Albini as attorney-in-fact for Arturo Molina 2019-09-30