JOINT FILING AGREEMENT

Exhibit 99.1

JOINT FILING AGREEMENT

We, the undersigned, hereby express our agreement that the attached Amendment No. 2 to Schedule 13G is filed on behalf of each of us.

Dated: June 24, 2020

THE COLUMN GROUP, LP						THE COLUMN GROUP GP, LP
By:		The Column Group GP, LP
By:		/s/ Xxxxx Xxxxxxxxxx				By:		/s/ Xxxxx Xxxxxxxxxx
Name:		Xxxxx Xxxxxxxxxx				Name:		Xxxxx Xxxxxxxxxx
Title:		Managing Partner				Title:		Managing Partner
PONOI CAPITAL, LP						PONOI MANAGEMENT, LLC
By:		Ponoi Management, LLC
By:		/s/ Xxxxx Xxxxxxxxxx				By:		/s/ Xxxxx Xxxxxxxxxx
Name:		Xxxxx Xxxxxxxxxx				Name:		Xxxxx Xxxxxxxxxx
Title:		Managing Partner				Title:		Managing Partner
PONOI CAPITAL II, LP						PONOI II MANAGEMENT, LLC
By:		Ponoi II Management, LLC
By:		/s/ Xxxxx Xxxxxxxxxx				By:		/s/ Xxxxx Xxxxxxxxxx
Name:		Xxxxx Xxxxxxxxxx				Name:		Xxxxx Xxxxxxxxxx
Title:		Managing Partner				Title:		Managing Partner
THE COLUMN GROUP III, LP						THE COLUMN GROUP III GP, LP
By:		The Column Group III GP, LP
By:		/s/ Xxxxx Xxxxxxxxxx				By:		/s/ Xxxxx Xxxxxxxxxx
Name:		Xxxxx Xxxxxxxxxx				Name:		Xxxxx Xxxxxxxxxx
Title:		Managing Partner				Title:		Managing Partner
THE COLUMN GROUP III-A, LP
						By:		/s/ Xxxxx X. Xxxxxxx
By:		The Column Group III GP, LP						Xxxxx X. Xxxxxxx
By:		/s/ Xxxxx Xxxxxxxxxx				By:		/s/ Xxx Xxxxxxx
Name:		Xxxxx Xxxxxxxxxx						Xxx Xxxxxxx
Title:		Managing Partner
						By:		/s/ Xxxxx Xxxxxxxxxx
								Xxxxx Xxxxxxxxxx