X0306 4 2018-10-01 0 0001382101 SUTRO BIOPHARMA INC STRO 0001296771 Freund John Gordon SKYLINE VENTURES 525 UNIVERSITY AVE., SUITE 1350 PALO ALTO CA 94301 1 0 1 0 Common Stock 2018-10-01 4 C 0 925578 A 925578 I By Skyline Venture Partners V, L.P. Common Stock 2018-10-01 4 C 0 520264 A 1445842 I By Skyline Venture Partners V, L.P. Common Stock 2018-10-01 4 C 0 514211 A 1960053 I By Skyline Venture Partners V, L.P. Series C Preferred Stock 2018-10-01 4 C 0 25015635 0.00 D Common Stock 925578 0 I By Skyline Venture Partners V, L.P. Series D Preferred Stock 2018-10-01 4 C 0 12846023 0.00 D Common Stock 520264 0 I By Skyline Venture Partners V, L.P. Series E Preferred Stock 2018-10-01 4 C 0 18698578 0.00 D Common Stock 514211 0 I By Skyline Venture Partners V, L.P. Each share of the issuer's Series C Preferred Stock automatically converted into 0.0370 share of the issuer's Common Stock on October 1, 2018 in connection with the closing of the issuer's sale of its Common Stock in its firm commitment initial public offering (the "IPO") pursuant to a registration statement on Form S-1 (File No. 333-227103) under the Securities Act of 1933, as amended (the "Registration Statement"), and had no expiration date. These securities are held of record by Skyline Venture Partners V, L.P. ("Skyline L.P."). Skyline Venture Management V, LLC ("Skyline Management") is the general partner of Skyline L.P. the reporting person, a member of the issuer's board of directors, together with Yasunori Kaneko, are the managing directors of Skyline Management, and each may be deemed to share voting and investment power over the securities held by Skyline L.P. The reporting person disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. Each share of the issuer's Series D Preferred Stock automatically converted into 0.0405 share of the issuer's Common Stock on October 1, 2018 in connection with the closing of the issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date. Each share of the issuer's Series E Preferred Stock automatically converted into 0.0275 share of the issuer's Common Stock on October 1, 2018 in connection with the closing of the issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date. /s/ Edward C. Albini as attorney-in-fact for John G. Freund 2018-10-01