Exhibit 1

Joint Filing Agreement

We, the undersigned, hereby express our agreement that the attached Schedule 13G (or any amendments thereto) relating to the Common Stock of Gritstone Oncology, Inc. is filed on behalf of each of us.

February __, 2021
Versant Venture Capital V, L.P.
By:	Versant Ventures V, LLC
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director
Versant Affiliates Fund V, L.P.
By:	Versant Ventures V, LLC
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director
Versant Ophthalmic Affiliates Fund I, L.P.
By:	Versant Ventures V, LLC
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director
Versant Ventures V, LLC
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director
Versant Venture Capital V (Canada) LP
By:	Versant Ventures V (Canada), L.P.
Its:	General Partner
By:	Versant Ventures V GP-GP (Canada), Inc.
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Director
Versant Ventures V (Canada), L.P.
By:	Versant Ventures V GP-GP (Canada), Inc.
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Director
Versant Ventures V GP-GP (Canada), Inc.
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Director
Versant Vantage I, L.P.
By:	Versant Vantage I GP, L.P.
Its:	General Partner
By:	Versant Vantage I GP-GP, LLC
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director
Versant Vantage I GP, L.P.
By:	Versant Vantage I GP-GP, LLC
Its:	General Partner
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director

Versant Vantage I GP-GP, LLC
By:	/s/ Robin L. Praeger
	Robin L. Praeger, Managing Director