Exhibit 99.1
JOINT FILING AGREEMENT
We, the undersigned, hereby express our agreement that the attached Schedule 13G is filed on behalf of each of us.
Dated: February 11, 2019
| THE COLUMN GROUP II, LP | THE COLUMN GROUP II GP, LP | |||||||
| By: | The Column Group II GP, LP | |||||||
| By: | /s/ Peter Svennilson | By: | /s/ Peter Svennilson | |||||
| Name: | Peter Svennilson | Name: | Peter Svennilson | |||||
| Title: | Managing Partner | Title: | Managing Partner | |||||
| By: | /s/ Peter Svennilson | |||||||
| Peter Svennilson | ||||||||
| By: | /s/ David V. Goeddel | |||||||
| David V. Goeddel | ||||||||
