Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue	$ 48,214	$ 4,037	$ 4,365
Operating expenses:
Research and development	97,490	88,643	82,896
General and administrative	25,933	21,411	19,409
Total operating expenses	123,423	110,054	102,305
Loss from operations	(75,209)	(106,017)	(97,940)
Interest income, net	127	703	3,507
Net loss	(75,082)	(105,314)	(94,433)
Other comprehensive gain (loss):
Unrealized gain (loss) on marketable securities	(73)	(24)	109
Comprehensive loss	$ (75,155)	$ (105,338)	$ (94,324)
Net loss per share, basic and diluted	$ (0.95)	$ (2.79)	$ (2.81)
Weighted-average number of shares used in computing net loss per share, basic and diluted	78,885,186	37,792,365	33,554,823
Collaboration and license revenues [Member]
Revenue	$ 46,717	$ 3,462	$ 4,365
Grant revenues [Member]
Revenue	$ 1,497	$ 575	$ 0