Consolidated Statements of Operations and Other Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Collaboration revenue	$ 26	$ 2,739	$ 1,026	$ 4,291
Operating expenses (income):
General and administrative	3,782	4,280	8,938	8,535
Research and development	9,592	8,762	19,675	18,577
Gain on right-of-use asset termination	(258)	0	(258)	0
Total operating expenses	13,116	13,042	28,355	27,112
Loss from operations	(13,090)	(10,303)	(27,329)	(22,821)
Other (expense) income:
Interest income, net	88	24	96	37
Interest expense, net	(206)	0	(230)	0
Total other (expense) income	(118)	24	(134)	37
Net loss	(13,208)	(10,279)	(27,463)	(22,784)
Unrealized (loss) from available-for-sale securities	0	0		(7)
Comprehensive loss	$ (13,208)	$ (10,279)	$ (27,463)	$ (22,791)
Net loss per common share – basic and diluted	$ (0.37)	$ (0.33)	$ (0.81)	$ (0.74)
Weighted average common shares outstanding – basic and diluted	35,357,343	31,233,794	34,005,410	30,834,522