Consolidated Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue:
Collaboration revenue - related party	$ 143,857,000	$ 11,897,000	$ 27,188,000
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Grant revenue	$ 1,070,000	$ 4,157,000	$ 1,102,000
Collaboration revenue		17,161,000	6,215,000
Total revenue	144,927,000	33,215,000	34,505,000
Operating expenses:
Research and development expenses	141,891,000	90,570,000	80,141,000
General and administrative expenses	69,261,000	30,775,000	24,748,000
Collaboration (profit) loss sharing - related party	(1,732,000)
Restructuring expenses	0	0	1,492,000
Total operating expenses	209,420,000	121,345,000	106,381,000
Loss from operations	(64,493,000)	(88,130,000)	(71,876,000)
Other (expense) income:
Interest income	2,870,000	946,000	1,033,000
Interest expense	(2,910,000)	(2,924,000)	(502,000)
Other (expense) income	(1,045,000)	981,000	1,066,000
Total other (expense) income, net	(1,085,000)	(997,000)	1,597,000
Net loss	$ (65,578,000)	$ (89,127,000)	$ (70,279,000)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.72)	$ (1.12)	$ (1.24)
Weighted average common shares outstanding, basic and diluted	91,702,866	79,789,220	56,649,220
Other comprehensive (loss):
Unrealized loss on investments, net of tax of $0	$ (12,000)	$ (47,000)
Currency translation adjustment	(1,000)
Total other comprehensive loss	(13,000)	(47,000)
Comprehensive loss	$ (65,591,000)	$ (89,174,000)	$ (70,279,000)