Sec Form 4 Filing - Petree Daniel H @ SUTRO BIOPHARMA INC - 2018-10-01

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

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1. Name and Address of Reporting Person Petree Daniel H 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 _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SUTRO BIOPHARMA, INC., 310 UTAH AVENUE, SUITE 150 3. Date of Earliest Transaction (MM/DD/YY) 10/01/2018 (Street) SOUTH SAN FRANCISCO, CA94080 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 M 314 A $ 5.81 314 I Daniel H. Petree and Susan M. Toeniskoetter Trust dated July 25, 1997 ( 1 ) Common Stock 10/01/2018 S( 2 ) 122 D $ 15 192 I Daniel H. Petree and Susan M. Toeniskoetter Trust dated July 25, 1997 ( 1 )

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 Common Stock Warrant (right to buy) $ 5.81 ( 3 ) 10/01/2018 M 314 ( 4 ) ( 4 ) Common Stock 314 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Petree Daniel H C/O SUTRO BIOPHARMA, INC. 310 UTAH AVENUE, SUITE 150 SOUTH SAN FRANCISCO, CA94080 X Signatures /s/ Edward C. Albini as attorney-in-fact for Daniel H. Petree 10/01/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These securities are held of record by the reporting person and his spouse as trustees of the Daniel H. Petree and Susan M. Toeniskoetter Trust dated July 25, 1997. ( 2 )On October 1, 2018, the reporting person exercised a warrant to purchase 314 shares of issuer's common stock for $5.81 per share. The reporting person paid the exercise price on a cashless basis, resulting in the issuer withholding 122 of the shares to pay the exercise price and issuing to the reporting person the remaining 192 shares. ( 3 )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. ( 4 )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.

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).

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