SEC Form 3

FORM 3

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

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1. Name and Address of Reporting Person* Longitude Prime Partners, LLC (Last) (First) (Middle) 2740 SAND HILL ROAD, SECOND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 01/31/2022	3. Issuer Name and Ticker or Trading Symbol Sierra Oncology, Inc. [ SRRA ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	175,000(1)	I	See footnote(2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* Longitude Prime Partners, LLC (Last) (First) (Middle) 2740 SAND HILL ROAD, SECOND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Longitude Prime Fund, L.P. (Last) (First) (Middle) 2740 SAND HILL ROAD, SECOND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Not included on this Form 3 are an additional 1,964,771 shares of Common Stock held by Longitude Venture Partners III, L.P. ("LVP III"). LVP III, Longitude Capital Partners III, LLC, Patrick G. Enright, Juliet Tammenoms Bakker and Joshua Richardson, a member of the Issuer's board of directors, have separately filed Form 4s in connection with the acquisition of the shares of Common Stock described in this Form.

2. The securities are held directly by Longitude Prime Fund, L.P. ("LPF"). Longitude Prime Partners, LLC ("LPP"), the general partner of LPF, may be deemed to have voting and investment power with respect to the shares held by LPF. Patrick G. Enright, Juliet Tammenoms Bakker and Joshua Richardson, a member of the Issuer's board of directors, are each members of LPF 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 LPP. Each of Mr. Enright, Ms. Tammenoms Bakker and Dr. Richardson disclaim beneficial ownership of such shares except to the extent of their respective pecuniary interests therein.

Remarks:

	Longitude Prime Partners, LLC, By: /s/ Patrick Enright, Managing Member	02/02/2022
	Longitude Prime Fund, L.P., By: /s/ Patrick Enright, Managing Member of the general partner	02/02/2022
	** Signature of Reporting Person	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 5 (b)(v).
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