Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Collaboration revenue	$ 43	$ 828	$ 42,123
Operating expenses:
Research and development	132,013	67,036	55,040
General and administrative	36,888	21,902	17,283
Total operating expenses	168,901	88,938	72,323
Other income (expense):
Interest income	65	424	2,226
Interest expense	(1,267)	(359)	(234)
Total other income (expense), net	(1,202)	65	1,992
Net loss	(170,060)	(88,045)	(28,208)
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	0	(25)	33
Comprehensive loss	(170,060)	(88,070)	(28,175)
Net loss attributable to common stockholders - basic	(170,060)	(88,045)	(28,208)
Net loss attributable to common stockholders - diluted	$ (170,060)	$ (88,045)	$ (28,208)
Net loss per share attributable to common stockholders — basic (in dollars per share)	$ (2.41)	$ (1.43)	$ (0.65)
Net loss per share attributable to common stockholders — diluted (in dollars per share)	$ (2.41)	$ (1.43)	$ (0.65)
Weighted-average number of shares of common stock used in net loss per share attributable to common stockholders — basic (in shares)	70,580,949	61,485,205	43,492,113
Weighted-average number of shares of common stock used in net loss per share attributable to common stockholders — diluted (in shares)	70,580,949	61,485,205	43,492,113