UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 1)¹

OncoMed Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, $0.001 par value

(Title of Class of Securities)

68234X102

(CUSIP Number)

JAMES KRATKY

BVF PARTNERS L.P.

44 Montgomery St., 40th Floor

San Francisco, California 94104

(415) 525-8890

ADAM W. FINERMAN, ESQ.

OLSHAN FROME WOLOSKY LLP

1325 Avenue of the Americas

New York, New York 10019

(212) 451-2300

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

April 23, 2019

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ☒.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 240.13d-7 for other parties to whom copies are to be sent.

1 The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			BIOTECHNOLOGY VALUE FUND, L.P.
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			DELAWARE
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			PN

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			BIOTECHNOLOGY VALUE FUND II, L.P.
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			DELAWARE
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			PN

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			BIOTECHNOLOGY VALUE TRADING FUND OS LP
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			CAYMAN ISLANDS
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			PN

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			BVF PARTNERS OS LTD.
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			CAYMAN ISLANDS
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			CO

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			BVF PARTNERS L.P.
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			DELAWARE
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			PN, IA

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			BVF INC.
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			DELAWARE
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			CO

CUSIP NO. 68234X102


	1	NAME OF REPORTING PERSON

			MARK N. LAMPERT
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☒
						(b) ☐

	3	SEC USE ONLY


	4	SOURCE OF FUNDS


	5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)				☐


	6	CITIZENSHIP OR PLACE OF ORGANIZATION

			USA
NUMBER OF			7	SOLE VOTING POWER
SHARES
BENEFICIALLY					- 0 -
OWNED BY			8	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			9	SOLE DISPOSITIVE POWER

					- 0 -
			10	SHARED DISPOSITIVE POWER

					- 0 -
	11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

			- 0 -
	12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES				☐


	13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

			0%
	14	TYPE OF REPORTING PERSON

			IN

CUSIP NO. 68234X102

The following constitutes Amendment No. 1 to the Schedule 13D filed by the undersigned (“Amendment No. 1”). This Amendment No. 1 amends the Schedule 13D as specifically set forth herein.

Item 4.

Purpose of Transaction

Item 4 is hereby amended to add the following:

On April 23, 2019, the acquisition of the Issuer by Mereo BioPharma Group plc (“Mereo”), was consummated pursuant to the terms of that certain Agreement and Plan of Merger and Reorganization, dated December 5, 2018 (the “Merger Agreement”), by and among the Issuer, Mereo, Mereo US Holdings Inc., a wholly owned subsidiary of Mereo (“HoldCo”) and Mereo MergerCo One Inc., a wholly owned subsidiary of HoldCo (“Merger Sub”). Pursuant to the Merger Agreement, Merger Sub merged with and into the Issuer (the “Merger”), with the Issuer surviving the Merger as a wholly owned subsidiary of Mereo. Effective April 23, 2019, each Share owned by the Reporting Persons was cancelled and automatically converted into the right to receive (A) American Depositary Shares, representing a number of ordinary shares, par value £0.003 per share of Mereo equal to the Exchange Ratio (as such term is defined in the Merger Agreement) (the “Share Consideration”), and (B) one contingent value right (together with the Share Consideration, the “Merger Consideration”). Accordingly, as a result of the Merger, the Reporting Persons no longer beneficially own any Shares of the Issuer.

Item 5.

Interest in Securities of the Issuer.

Item 5 is hereby amended and restated to read as follows:

(a)-(b) Effective April 23, 2019, as a result of the Merger, each Share owned by the Reporting Persons was converted into the right to receive the Merger Consideration, pursuant to the Merger Agreement. Accordingly, the Reporting Persons no longer beneficially own any Shares of the Issuer.

(d) Not applicable.

(e) As of April 23, 2019, the Reporting Persons ceased to be the beneficial owners of more than 5% of the Shares of the Issuer.

CUSIP NO. 68234X102

SIGNATURES

After reasonable inquiry and to the best of his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: April 26, 2019

BIOTECHNOLOGY VALUE FUND, L.P.		BVF INC.
		BVF INC.
By:	BVF Partners L.P., its general partner	By:	/s/ Mark N. Lampert
By:	BVF Inc., its general partner		Mark N. Lampert
			President
By:	/s/ Mark N. Lampert
	Mark N. Lampert
	President	/s/ Mark N. Lampert
		MARK N. LAMPERT

BIOTECHNOLOGY VALUE FUND II, L.P.

By:	BVF Partners L.P., its general partner
By:	BVF Inc., its general partner

By:	/s/ Mark N. Lampert
	Mark N. Lampert
	President


BVF PARTNERS L.P.

By:	BVF Inc., its general partner

By:	/s/ Mark N. Lampert
	Mark N. Lampert
	President


BVF PARTNERS OS LTD.

By:	BVF Partners L.P., its sole member
By:	BVF Inc., its general partner

By:	/s/ Mark N. Lampert
	Mark N. Lampert
	President


Biotechnology Value Trading Fund OS LP

By:	BVF Partners L.P., its investment manager
By:	BVF Inc., its general partner

By:	/s/ Mark N. Lampert
	Mark N. Lampert
	President

OncoMed Pharmaceuticals Inc SC 13D/A