CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Revenue from collaborations	$ 3,693	$ 1,545	$ 6,264	$ 2,455
Operating expenses:
Research and development	16,510	24,554	48,186	47,422
General and administrative	7,576	6,556	14,028	12,337
Total operating expenses	24,086	31,110	62,214	59,759
Loss from operations	(20,393)	(29,565)	(55,950)	(57,304)
Interest and other income (expense), net	516	(225)	510	(114)
Loss before income tax expense	(19,877)	(29,790)	(55,440)	(57,418)
Income tax expense	(47)	(28)	(99)	(74)
Net loss	(19,924)	(29,818)	(55,539)	(57,492)
Other comprehensive income (loss):
Unrealized loss on available-for-sale securities	(154)	(26)	(402)	(66)
Unrealized gain on pension plans		2		3
Other comprehensive loss	(154)	(24)	(402)	(63)
Comprehensive loss	$ (20,078)	$ (29,842)	$ (55,941)	$ (57,555)
Net loss per share, basic and diluted	$ (0.47)	$ (0.79)	$ (1.30)	$ (1.53)
Weighted average shares of common stock, basic and diluted	42,665,598	37,619,039	42,590,479	37,526,650