Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue:
Contract revenue	$ 0	$ 1,460	$ 2,301	$ 2,371
Total revenue	0	1,460	2,301	2,371
Operating expenses:
Research and development	2,938	13,288	17,940	42,030
General and administrative	3,315	3,930	10,892	14,282
Restructuring expenses	2,797	0	6,039	0
Total operating expenses	9,050	17,218	34,871	56,312
Loss from operations	(9,050)	(15,758)	(32,570)	(53,941)
Other income (expense)
Change in fair value of warrant liability	9	128	90	(3,191)
Change in fair value of convertible notes	0	0	0	(7,469)
Change in fair value of Series C convertible preferred stock	0	0	0	(3,592)
Gain upon debt extinguishment	0	0	0	905
Foreign exchange transaction loss	(215)	(204)	(441)	(279)
Earnings from equity method investment	9	20	151	40
Interest income (expense), net	259	110	403	(1,936)
Total other income (expense)	62	54	203	(15,522)
Net loss	(8,988)	(15,704)	(32,367)	(69,463)
Other comprehensive income:
Foreign currency translation adjustment	204	146	405	260
Comprehensive loss	$ (8,784)	$ (15,558)	$ (31,962)	$ (69,203)
Net loss per common share, basic (in dollars per share)	$ (0.30)	$ (0.53)	$ (1.08)	$ (2.51)
Net loss per common share, diluted (in dollars per share)	$ (0.30)	$ (0.53)	$ (1.08)	$ (2.51)
Weighted average common shares outstanding, basic (in shares)	30,113,407	29,829,577	30,016,079	27,671,310
Weighted average common shares outstanding, diluted (in shares)	30,113,407	29,829,577	30,016,079	27,671,310