EXHIBIT A
AGREEMENT
Pursuant toRule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of Common Stock of Gritstone Oncology, Inc.
| Date: February 14, 2019 | FRAZIER HEALTHCARE VII, L.P. | |||||
| By FHM VII, L.P., its general partner | ||||||
| By FHM VII, L.L.C., its general partner | ||||||
| By: | /s/ Steve R. Bailey | |||||
| Steve R. Bailey, Chief Financial Officer | ||||||
| Date: February 14, 2019 | FRAZIER HEALTHCAREVII-A, L.P. | |||||
| By FHM VII, L.P., its general partner | ||||||
| By FHM VII, L.L.C., its general partner | ||||||
| By: | /s/ Steve R. Bailey | |||||
| Steve R. Bailey, Chief Financial Officer | ||||||
| Date: February 14, 2019 | FHM VII, L.P. | |||||
| By FHM VII, L.L.C., its general partner | ||||||
| By: | /s/ Steve R. Bailey | |||||
| Steve R. Bailey, Chief Financial Officer | ||||||
| Date: February 14, 2019 | FHM VII, L.L.C. | |||||
| By: | /s/ Steve R. Bailey | |||||
| Steve R. Bailey, Chief Financial Officer | ||||||
| Date: February 14, 2019 | By: | * | ||||
| James Topper | ||||||
| Date: February 14, 2019 | By: | * | ||||
| Patrick Heron | ||||||
| Date: February 14, 2019 | By: | * | ||||
| Nader Naini | ||||||
| Date: February 14, 2019 | By: | * | ||||
| Nathan Every | ||||||
| Date: February 14, 2019 | By: | * | ||||
| Brian Morfitt | ||||||
| Date: February 14, 2019 | By: | * | ||||
| Alan Frazier | ||||||
| Date: February 14, 2019 | *By: | /s/ Steve R. Bailey | ||||
| Steve R. Bailey, asAttorney-in-Fact | ||||||
This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on March 29, 2016.
