Sec Form 4 Filing - Ross Michael Jay @ SUTRO BIOPHARMA INC - 2018-09-27

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Ross Michael Jay 2. Issuer Name and Ticker or Trading Symbol SUTRO BIOPHARMA INC [ STRO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) SV HEALTH INVESTORS, LLC, ONE BOSTON PL., 201 WASHINGTON ST. #3900 3. Date of Earliest Transaction (MM/DD/YY) 09/27/2018 (Street) BOSTON, MA02108 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 10/01/2018 C 943 A 943 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Common Stock 10/01/2018 C 7,610 A 8,553 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Common Stock 10/01/2018 C 2,399 A 10,952 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Common Stock 10/01/2018 C 79,467 A 79,467 I By International Life Sciences Fund III (LP1), L.P. ( 2 ) Common Stock 10/01/2018 C 641,440 A 720,907 I By International Life Sciences Fund III (LP1), L.P. ( 2 ) Common Stock 10/01/2018 C 202,115 A 923,022 I By International Life Sciences Fund III (LP1), L.P. ( 2 ) Common Stock 10/01/2018 C 758 A 758 I By Internation al Life Sciences Fund III Strategic Partners, L.P. ( 2 ) Common Stock 10/01/2018 C 6,128 A 6,886 I By International Life Sciences Fund III Strategic Partners, L.P. ( 2 ) Common Stock 10/01/2018 C 1,931 A 8,817 I By International Life Sciences Fund III Strategic Partners, L.P. ( 2 ) Common Stock 10/01/2018 C 341,030 A 341,030 I By SV Life Sciences Fund V, L.P. ( 5 ) Common Stock 10/01/2018 C 270,690 A 611,720 I By SV Life Sciences Fund V, L.P. ( 5 ) Common Stock 10/01/2018 C 251,783 A 863,503 I By SV Life Sciences Fund V, L.P. ( 5 ) Common Stock 10/01/2018 C 7,207 A 7,207 I By SV Life Sciences Fund V Strategic Partners, L.P. ( 5 ) Common Stock 10/01/2018 C 5,721 A 12,928 I By SV Life Sciences Fund V Strategic Partners, L.P. ( 5 ) Common Stock 10/01/2018 C 5,320 A 18,248 I By SV Life Sciences Fund V Strategic Partners, L.P. ( 5 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series C Preferred Stock Warrant (right to buy) $ 0.4797 09/27/2018 M 6,183 ( 8 ) ( 8 ) Series C Preferred Stock 6,183 $ 0 5,361 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Series C Preferred Stock ( 9 ) 09/27/2018 M 6,183 ( 9 ) ( 9 ) Common Stock 228 $ 0 64,815 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Series C Preferred Stock Warrant (right to buy) $ 0.4797 09/27/2018 M 521,159 ( 8 ) ( 8 ) Series C Preferred Stock 521,159 $ 0 451,869 I By International Life Sciences Fund III (LPI) L.P. ( 2 ) Series C Preferred Stock ( 9 ) 09/27/2018 M 521,159 ( 9 ) ( 9 ) Common Stock 19,282 $ 0 5,462,550 I By International Life Sciences Fund III (LPI) L.P. ( 2 ) Series C Preferred Stock Warrant (right to buy) $ 0.4797 09/27/2018 M 4,978 ( 8 ) ( 8 ) Series C Preferred Stock 4,978 $ 0 4,315 I By International Life Sciences Fund III Strategic Partners L.P. ( 2 ) Series C Preferred Stock ( 9 ) 09/27/2018 M 4,978 ( 9 ) ( 9 ) Common Stock 184 $ 0 52,183 I By International Life Sciences Fund III Strategic Partners L.P. ( 2 ) Series A Preferred Stock ( 1 ) 10/01/2018 C 21,776 ( 1 ) ( 1 ) Common Stock 943 $ 0 0 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Series B Preferred Stock ( 3 ) 10/01/2018 C 131,683 ( 3 ) ( 3 ) Common Stock 7,610 $ 0 0 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Series C Preferred Stock ( 4 ) 10/01/2018 C 64,815 ( 4 ) ( 4 ) Common Stock 2,399 $ 0 0 I By International Life Sciences Fund III Co-Investment, L.P. ( 2 ) Series A Preferred Stock ( 1 ) 10/01/2018 C 1,835,270 ( 1 ) ( 1 ) Common Stock 79,467 $ 0 0 I By International Life Sciences Fund III (LP1), L.P. ( 2 ) Series B Preferred Stock ( 3 ) 10/01/2018 C 11,097,596 ( 3 ) ( 3 ) Common Stock 641,440 $ 0 0 I By International Life Sciences Fund III (LP1), L.P. ( 2 ) Series C Preferred Stock ( 4 ) 10/01/2018 C 5,462,550 ( 4 ) ( 4 ) Common Stock 202,115 $ 0 0 I By International Life Sciences Fund III (LP1), L.P. ( 2 ) Series A Preferred Stock ( 1 ) 10/01/2018 C 17,533 ( 1 ) ( 1 ) Common Stock 758 $ 0 0 I By International Life Sciences Fund III Strategic Partners, L.P. ( 2 ) Series B Preferred Stock ( 3 ) 10/01/2018 C 106,019 ( 3 ) ( 3 ) Common Stock 6,128 $ 0 0 I By International Life Sciences Fund III Strategic Partners, L.P. ( 2 ) Series C Preferred Stock ( 4 ) 10/01/2018 C 52,183 ( 4 ) ( 4 ) Common Stock 1,931 $ 0 0 I By International Life Sciences Fund III Strategic Partners, L.P. ( 2 ) Series C Preferred Stock ( 4 ) 10/01/2018 C 9,217,015 ( 4 ) ( 4 ) Common Stock 341,030 $ 0 0 I By SV Life Sciences Fund V, L.P. ( 5 ) Series D Preferred Stock ( 6 ) 10/01/2018 C 6,683,697 ( 6 ) ( 6 ) Common Stock 270,690 $ 0 0 I By SV Life Sciences Fund V, L.P. ( 5 ) Series E Preferred Stock ( 7 ) 10/01/2018 C 9,155,794 ( 7 ) ( 7 ) Common Stock 251,783 $ 0 0 I By SV Life Sciences Fund V, L.P. ( 5 ) Series C Preferred Stock ( 4 ) 10/01/2018 C 194,786 ( 4 ) ( 4 ) Common Stock 7,207 $ 0 0 I By SV Life Sciences Fund V Strategic Partners, L.P. ( 5 ) Series D Preferred Stock ( 6 ) 10/01/2018 C 141,249 ( 6 ) ( 6 ) Common Stock 5,721 $ 0 0 I By SV Life Sciences Fund V Strategic Partners, L.P. ( 5 ) Series E Preferred Stock ( 7 ) 10/01/2018 C 193,492 ( 7 ) ( 7 ) Common Stock 5,320 $ 0 0 I By SV Life Sciences Fund V Strategic Partners, L.P. ( 5 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Ross Michael Jay SV HEALTH INVESTORS, LLC ONE BOSTON PL., 201 WASHINGTON ST. #3900 BOSTON, MA02108 X X Signatures /s/ Edward C. Albini as attorney-in-fact for Michael J. Ross 10/01/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of the issuer's Series A Preferred Stock automatically converted into 0.0433 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 initial public offering ("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. ( 2 )These securities are held of record by each of International Life Sciences Fund III Co-Investment, L.P., International Life Sciences Fund III (LP1) L.P. and International Life Sciences Fund III Strategic Partners L.P., as applicable (together, the "ILSF Funds"). ILSF III, LLC ("ILSF LLC") is the general partner of International Life Sciences Fund III (GP), L.P., which is the general partner of each of the ILSF Funds. The reporting person, a member of the issuer's board of directors, is a member of ILSF LLC's investment committee, and may be deemed to share voting and investment power over the securities held by the ILSF Funds. 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. ( 3 )Each share of the issuer's Series B Preferred Stock automatically converted into 0.0578 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. ( 4 )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 IPO pursuant to the Registration Statement, and had no expiration date. ( 5 )These securities are held of record by each of SV Life Sciences Fund V, L.P. and SV Life Sciences Fund V Strategic Partners, L.P., as applicable (together, the "SVLSF Funds"). SVLSF V, LLC ("SVLSF LLC") is the general partner of SV Life Sciences Fund V (GP), L.P., which is the general partner of each of the SVLSF Funds. The reporting person, a member of the issuer's board of directors, is a member of SVLSF LLC's investment committee, and may be deemed to share voting and investment power over the securities held by the SVLSF Funds. 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. ( 6 )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. ( 7 )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. ( 8 )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. ( 9 )Each share of the issuer's Series C Preferred Stock will automatically convert into 0.0370 share of the issuer's Common Stock immediately upon the closing of the issuer's IPO and has no expiration date.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.