Sec Form 4 Filing - Longitude Capital Partners III, LLC @ Sierra Oncology, Inc. - 2022-01-25

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 Longitude Capital Partners III, LLC 2. Issuer Name and Ticker or Trading Symbol Sierra Oncology, Inc. [ SRRA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 2740 SAND HILL ROAD, SECOND FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 01/25/2022 (Street) MENLO PARK, CA94025 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 01/25/2022 X 487,451 A $ 13.2 1,964,771 I See footnote( 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 Series B Warrants $ 13.2 01/25/2022 X 1,477,125( 2 ) 01/22/2020 04/10/2022 Common Stock 487,451 $ 13.2 0 I See footnote( 1 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Longitude Capital Partners III, LLC 2740 SAND HILL ROAD SECOND FLOOR MENLO PARK, CA94025 X Longitude Venture Partners III, L.P. 2740 SAND HILL ROAD SECOND FLOOR MENLO PARK, CA94025 X Tammenoms Bakker Juliet 2740 SAND HILL ROAD SECOND FLOOR MENLO PARK, CA94025 X ENRIGHT PATRICK G 2740 SAND HILL ROAD SECOND FLOOR MENLO PARK, CA94025 X Signatures Longitude Venture Partners III, L.P.; By /s/ Patrick G. Enright, Managing Member 01/27/2022 Signature of Reporting Person Date Longitude Capital Partners III, LLC; By /s/ Patrick G. Enright, Managing Member 01/27/2022 Signature of Reporting Person Date /s/ Juliet Tammenoms Bakker 01/27/2022 Signature of Reporting Person Date /s/ Patrick G. Enright 01/27/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These securities are held directly by Longitude Venture Partners III, L.P. ("LVP III"). Longitude Capital Partners III, LLC ("LCP III") is the general partner of LVP III and may be deemed to have voting, investment and dispositive power with respect to such securities. Patrick G. Enright, Juliet Tammenoms Bakker and Joshua Richardson, a member of the Issuer's board of directors, are each members of LCP III and may be deemed to share voting, investment and dispositive power over such securities. Mr. Enright and Ms. Tammenoms Bakker are the managing members of LCP III. Each of LCP III, Mr. Enright, Ms. Tammenoms Bakker and Joshua Richardson disclaim beneficial ownership over such securities except to the extent of their respective pecuniary interest therein, and the inclusion of such 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 purpose. ( 2 )Consists of 1,477,125 Series B Warrants held by LVP III which are exercisable for an aggregate of 487,451 shares of Common Stock.

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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