X0206 3 2018-09-26 0 0001382101 SUTRO BIOPHARMA INC STRO 0001294939 Petree Daniel H C/O SUTRO BIOPHARMA, INC. 310 UTAH AVENUE, SUITE 150 SOUTH SAN FRANCISCO CA 94080 1 0 0 0 No securities beneficially held 0 D Common Stock Warrant (right to buy) 5.808 Common Stock 314 D Stock Option (right to buy Common Stock) 5.09 2019-03-24 Common Stock 3030 D Stock Option (right to buy Common Stock) 5.09 2019-09-08 Common Stock 826 D Stock Option (right to buy Common Stock) 4.36 2021-02-08 Common Stock 4132 D Stock Option (right to buy Common Stock) 4.36 2022-04-17 Common Stock 4545 D Stock Option (right to buy Common Stock) 4.36 2022-09-19 Common Stock 2617 D Stock Option (right to buy Common Stock) 5.81 2023-02-13 Common Stock 578 D Stock Option (right to buy Common Stock) 5.81 2023-02-13 Common Stock 873 D Stock Option (right to buy Common Stock) 5.81 2024-02-26 Common Stock 2124 D Stock Option (right to buy Common Stock) 5.81 2024-02-26 Common Stock 3540 D Stock Option (right to buy Common Stock) 11.98 2025-09-27 Common Stock 1456 D Stock Option (right to buy Common Stock) 11.98 2025-09-27 Common Stock 2427 D The warrant is exercisable at any time at the holder's election on a one-for one basis and automatically terminates on the completion of the issuer's initial public offering if not earlier exercised. The warrant has a net exercise provision under which the holder, in lieu of paying the exercise price in cash, can surrender the warrant and receive a net number of shares of common stock based on the fair market value of such stock at the time of exercise, after deducting the aggregate exercise price. The option is fully vested. The option vests as to 2.0833% of the total shares monthly, beginning on October 15, 2015, with 100% of the total shares vested and exercisable on September 15, 2019, subject to the reporting person's provision of service to the issuer on each vesting date. /s/ Edward C. Albini as attorney-in-fact for Daniel H. Petree 2018-09-26