Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statements of Operations
License and collaboration revenue - related party	$ 27,357,000	$ 28,628,000	$ 231,000
Revenue from Contract with Customer, Product and Service [Extensible List]	License and Collaboration Agreement	License and Collaboration Agreement	License and Collaboration Agreement
Operating expenses:
Research and development	$ 126,006,000	$ 74,506,000	$ 65,003,000
General and administrative	27,196,000	18,638,000	15,749,000
Total operating expenses	153,202,000	93,144,000	80,752,000
Loss from operations	(125,845,000)	(64,516,000)	(80,521,000)
Interest income	443,000	900,000	2,813,000
Interest expense		(598,000)	(169,000)
Loss on early repayment of debt		(585,000)
Other expense, net	(149,000)	(46,000)	(1,000)
Loss before income tax (expense) benefit	(125,551,000)	(64,845,000)	(77,878,000)
Income tax (expense) benefit	0	(1,305,000)	691,000
Net loss	$ (125,551,000)	$ (66,150,000)	$ (77,187,000)
Net loss per share, basic and diluted	$ (2.71)	$ (1.92)	$ (2.98)
Weighted-average shares used to compute net loss per share, basic and diluted	46,322,910	34,396,446	25,894,024