Sec Form 4 Filing - Topper James N @ Sierra Oncology, Inc. - 2017-02-14

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 Topper James N 2. Issuer Name and Ticker or Trading Symbol Sierra Oncology, Inc. [ SRRA] 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) C/O FRAZIER HEALTHCARE, 601 UNION ST., TWO UNION SQ., STE. 3200 3. Date of Earliest Transaction (MM/DD/YY) 02/14/2017 (Street) SEATTLE, WA98101 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 02/14/2017 P 5,925,926 A $ 1.35 5,925,926 I By Frazier Life Sciences VIII, L.P. ( 1 ) Common Stock 2,186,195 I By Frazier Healthcare VI, L.P. ( 2 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Topper James N C/O FRAZIER HEALTHCARE 601 UNION ST., TWO UNION SQ., STE. 3200 SEATTLE, WA98101 X X Signatures /s/ Sukhi Jagpal as attorney-in-fact for James Topper, M.D., Ph.D. 02/16/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The reporting person and Patrick Heron are the managing members of FHM Life Sciences VIII, L.L.C., which is the general partner of FHM Life Sciences VIII, L.P., which is the general partner of Frazier Life Sciences VIII, L.P. ("FLSIII"), the record holder of the securities, and the reporting person may be deemed to share voting and dispositive power over the securities held by FLSIII. 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. ( 2 )The reporting person, Alan Frazier, Nader Naini, Nathan Every and Patrick Heron are the managing members of FHM VI, LLC, which is the general partner of FHM VI, LP, which is the general partner of Frazier Healthcare VI, L.P. ("FHVI"), the record holder of the securities, and the reporting person may be deemed to share voting and dispositive power over the securities held by FHVI. 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.

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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