JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k)(1)(iii) under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them of a Statement on Schedule 13D dated March 15, 2019 (including amendments thereto) with respect to the shares of Common Stock $0.001 par value, of OncoMed Pharmaceuticals, Inc. This Joint Filing Agreement shall be filed as an Exhibit to such Statement.

Dated: March 15, 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