SEC Form 4

FORM 4		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 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* ORBIMED ADVISORS LLC (Last) (First) (Middle) 601 LEXINGTON AVE., 54TH FLOOR (Street) NEW YORK NY 10022 (City) (State) (Zip)	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)
	3. Date of Earliest Transaction (Month/Day/Year) 01/29/2020
	4. 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 Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	01/29/2020		C		1,477,320(1)	A	$0.00(2)	1,477,320(1)	I	See footnotes(3)(4)

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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 A Convertible Voting Preferred Stock	(2)	01/29/2020		C			19,500	(2)	(2)	Common Stock	1,477,320(1)	(2)	0	I	See footnotes(3)(4)(5)

1. Name and Address of Reporting Person* ORBIMED ADVISORS LLC (Last) (First) (Middle) 601 LEXINGTON AVE., 54TH FLOOR (Street) NEW YORK NY 10022 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* OrbiMed Capital GP VII LLC (Last) (First) (Middle) 601 LEXINGTON AVENUE, 54TH FLOOR (Street) NEW YORK NY 10022 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* OrbiMed Global Healthcare GP LLC (Last) (First) (Middle) 601 LEXINGTON AVENUE, 54TH FLOOR (Street) NEW YORK NY 10022 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* ORBIMED CAPITAL LLC (Last) (First) (Middle) 601 LEXINGTON AVENUE, 54TH FLOOR (Street) NEW YORK NY 10022 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. On January 22, 2020, a 1-for-40 reverse split of the Issuer's Common Stock (the "Reverse Split") was effected. These securities reflect the Reverse Split.

2. Each share of Series A Convertible Voting Preferred Stock (the "Series A Preferred Stock") converted into 75.76 shares of the Issuer's Common Stock, as adjusted for the Reverse Split, automatically upon the 5th trading date following the Issuer's announcement of receiving stockholder approval for the first reverse stock split of the Issuer following November 13, 2019. The Series A Preferred Stock has no expiration date.

3. Consists of 1,136,400 shares of Common Stock held of record by OrbiMed Private Investments VII, LP ("OPI VII"), 170,460 shares of Common Stock held of record by OrbiMed Partners Master Fund Limited ("OPM") and 170,460 shares of Common Stock held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis"), as adjusted for the Reverse Split. OrbiMed Capital GP VII LLC ("GP VII") is the general partner of OPI VII. OrbiMed Advisors is the managing member of GP VII. OrbiMed Global Healthcare GP LLC ("Healthcare GP") is the general partner of Genesis and OrbiMed Advisors is the managing member of Healthcare GP. OrbiMed Capital LLC ("OrbiMed Capital") is the investment manager of OPM and OrbiMed Capital is a relying advisor of OrbiMed Advisors. (Continued in footnote 4)

4. GP VII and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VII and as a result may be deemed to have beneficial ownership of such securities; Healthcare GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by Genesis and as a result, may be deemed to have beneficial ownership over such securities; and OrbiMed Capital may be deemed to have voting power and investment power over the securities held by OPM and as a result, may be deemed to have beneficial ownership over such securities. Each of GP VII, Healthcare GP, OrbiMed Advisors and OrbiMed Capital disclaims beneficial ownership of the shares held by OPI VII, Genesis or OPM, as applicable, except to the extent of its or her pecuniary interest therein, if any.

5. Consists of 19,500 shares of Series A Preferred Stock which are convertible into an aggregate of 1,477,320 shares of Common Stock, as adjusted for the Reverse Split. Of the shares reported, 15,000 shares of Series A Preferred Stock are held of record by OPI VII, 2,250 shares of Series A Preferred Stock are held of record by Genesis, and 2,250 shares of Series A Preferred Stock are held of record by OPM.

Remarks:

	OrbiMed Advisors LLC; By /s/Douglas Coon, Chief Compl Ofcr. OrbiMed Capital GP VII; By /s/Douglas Coon, Chief Compl Ofcr. OrbiMed Capital LLC; By /s/Douglas Coon, Chief Compl Ofcr. OrbiMed Global Healthcare GP LLC; By /s/Douglas Coon, Chief Compl Ofcr.	01/31/2020
	** Signature of Reporting Person	Date
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