Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Total collaboration and license revenues	$ 9,461	$ 1,750	$ 18,922	$ 3,500
Type of Revenue [Extensible List]	Collaboration	Collaboration	Collaboration	Collaboration
Total collaboration and license revenues	$ 9,461	$ 1,750	$ 18,922	$ 3,500
Operating expenses:
Research and development (($1,176), $0, ($6,100) and $0 from a related party)	68,771	35,693	135,158	58,835
General and administrative	16,826	11,432	32,647	18,440
Total operating expenses	85,597	47,125	167,805	77,275
Loss from operations	(76,136)	(45,375)	(148,883)	(73,775)
Non-operating income (expense):
Interest and other income, net	166	301	320	948
Gain on deemed sale from equity method investee		131		613
Share of loss from equity method investee		(131)		(613)
Total non-operating income, net	166	301	320	948
Net loss	(75,970)	(45,074)	(148,563)	(72,827)
Other comprehensive income (loss)	(44)	(144)	(90)	80
Comprehensive loss	$ (76,014)	$ (45,218)	$ (148,653)	$ (72,747)
Net loss per share, basic and diluted	$ (1.09)	$ (0.93)	$ (2.17)	$ (1.57)
Weighted-average number of shares used to compute basic and diluted net loss per share	69,745,297	48,556,843	68,421,086	46,419,724