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
Revenue:
Contract revenue	$ 653	$ 540	$ 2,301	$ 911
Total revenue	653	540	2,301	911
Operating expenses:
Research and development	6,073	14,444	17,740	28,742
General and administrative	3,615	4,340	8,081	10,352
Total operating expenses	9,688	18,784	25,821	39,094
Loss from operations	(9,035)	(18,244)	(23,520)	(38,183)
Other income (expense)
Change in fair value of warrant liability	42	200	81	(3,319)
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	905	0	905
Foreign exchange transaction loss	(337)	(22)	(226)	(75)
Earnings from equity method investment	133	(35)	142	20
Interest income (expense), net	58	124	144	(2,046)
Total other income (expense)	(104)	1,172	141	(15,576)
Net loss	(9,139)	(17,072)	(23,379)	(53,759)
Other comprehensive income:
Foreign currency translation adjustment	297	68	201	114
Comprehensive loss	$ (8,842)	$ (17,004)	$ (23,178)	$ (53,645)
Net loss per common share, basic (in dollars per share)	$ (0.30)	$ (0.58)	$ (0.78)	$ (2.02)
Net loss per common share, diluted (in dollars per share)	$ (0.30)	$ (0.58)	$ (0.78)	$ (2.02)
Weighted average common shares outstanding, basic (in shares)	29,973,886	29,670,329	29,966,609	26,574,290
Weighted average common shares outstanding, diluted (in shares)	29,973,886	29,670,329	29,966,609	26,574,290