Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Collaboration revenue - related party	$ 0	$ 38,592	$ 15,360
License-related revenue	2,687	87,570	0
Total revenue	2,687	126,162	15,360
Operating expenses:
Research and development	53,572	41,018	52,118
General and administrative	25,128	23,558	20,608
Total operating expenses	78,700	64,576	72,726
Income (loss) from operations	(76,013)	61,586	(57,366)
Interest expense	(2,546)	(2,855)	(145)
Other income (expense), net	74	606	2,722
Net income (loss)	$ (78,485)	$ 59,337	$ (54,789)
Net income (loss) per share - basic (in dollars per share)	$ (1.77)	$ 1.67	$ (1.97)
Weighted average commons shares outstanding—basic (shares)	44,243,317	35,545,121	27,854,912
Net income (loss) per share - diluted (in dollars per share)	$ (1.77)	$ 1.57	$ (1.97)
Weighted average common shares outstanding—diluted (shares)	44,243,317	38,141,793	27,854,912
Comprehensive income (loss):
Net income (loss)	$ (78,485)	$ 59,337	$ (54,789)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net of tax	(221)	(103)	222
Comprehensive income (loss)	$ (78,706)	$ 59,234	$ (54,567)