EXHIBIT 1
AGREEMENT REGARDING JOINT FILING OF SCHEDULE 13G
Pursuant to Rule13d-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 shares of Common Stock of Sierra Oncology, Inc.
Date: February 12, 2019
| NEW LEAF BIOPHARMA OPPORTUNITIES I, L.P. | ||||||||
| By: | NEW LEAF BPO ASSOCIATES I, L.P. | |||||||
| Its General Partner | ||||||||
| By: | NEW LEAF VENTURE MANAGEMENT III, L.L.C. | |||||||
| Its General Partner | ||||||||
| By: | /s/ Craig L. Slutzkin | |||||||
| Craig L. Slutzkin | ||||||||
| Chief Financial Officer | ||||||||
| NEW LEAF BPO ASSOCIATES I, L.P. | ||||||||
| By: | NEW LEAF VENTURE MANAGEMENT III, L.L.C. | |||||||
| Its General Partner | ||||||||
| By: | /s/ Craig L. Slutzkin | |||||||
| Craig L. Slutzkin | ||||||||
| Chief Financial Officer | ||||||||
| NEW LEAF VENTURE MANAGEMENT III, L.L.C. | ||||||||
| By: | /s/ Craig L. Slutzkin | |||||||
| Craig L. Slutzkin | ||||||||
| Chief Financial Officer | ||||||||
* | ||||||||
| Vijay Lathi | ||||||||
* | ||||||||
| Ronald Hunt | ||||||||
* | ||||||||
| Liam Ratcliffe | ||||||||
/s/ Craig L. Slutzkin |
| * Craig L. Slutzkin |
| Asattorney-in-fact |
| * | This Schedule 13G was executed by Craig L. Slutzkin on behalf of the individuals listed above pursuant to Powers of Attorney. Note that copies of the applicable Powers of Attorney are already on file with the appropriate agencies. |