Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 7,572	$ 41,817	$ 57,052
Operating expenses:
Research and development	(77,549)	(66,193)	(47,353)
General and administrative	(27,558)	(17,269)	(10,930)
Total operating expenses	(105,107)	(83,462)	(58,283)
Loss from operations	(97,535)	(41,645)	(1,231)
Interest and other income (expense), net	272	112	600
Net loss	(97,263)	(41,533)	(631)
Accretion to redemption value and dividends on redeemable convertible preferred stock	0	0	(6,225)
Net loss attributable to common stockholders	$ (97,263)	$ (41,533)	$ (6,856)
Net loss per share, attributable to common stockholders:
Basic (in dollars per share)	$ (2.71)	$ (1.95)	$ (4.22)
Diluted (in dollars per share)	$ (2.71)	$ (1.95)	$ (4.22)
Shares used in computing net loss per share attributable to common stockholders:
Basic (in shares)	35,846,421	21,344,236	1,623,358
Diluted (in shares)	35,846,421	21,344,236	1,623,358
Comprehensive loss:
Net loss	$ (97,263)	$ (41,533)	$ (631)
Other comprehensive loss:
Net unrealized loss on short-term investments	(169)	(31)	(1)
Total other comprehensive loss	(169)	(31)	(1)
Comprehensive loss	$ (97,432)	$ (41,564)	$ (632)