Partner Fund Management SC 13G Sierra Oncology / PFM Health Sciences ownership change

EXHIBIT 99.1

JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on Schedule 13G filed herewith (and any amendments thereto), relating to the common stock of Sierra Oncology, Inc., a California corporation, is being filed jointly with the Securities and Exchange Commission pursuant to Rule 13d-1(c) under the Securities Exchange Act of 1934, as amended, on behalf of each of the undersigned.

This Agreement may be executed in counterparts and each of such counterparts taken together shall constitute one and the same instrument.

Dated this 7^th day of February, 2022.

PFM HEALTH SCIENCES, LP		PFM HEALTH SCIENCES GP, LLC
By:	PFM Health Sciences GP, LLC	By:	/s/ Darin Sadow
	its general partner		Darin Sadow, Authorized Signatory
By:	/s/ Darin Sadow
	Darin Sadow, Authorized Signatory

BRIAN D. GROSSMAN		PARTNER ASSET MANAGEMENT, LLC
By:	/s/ Darin Sadow	By:	PFM Health Sciences GP, LLC
	Darin Sadow, attorney-in-fact*		its manager
		By:	/s/ Darin Sadow
			Darin Sadow, Authorized Signatory