CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses
Research and development	$ 6,342	$ 15,622	$ 30,069	$ 32,544
General and administrative	9,082	7,497	26,839	28,174
Total operating expenses	15,424	23,119	56,908	60,718
Loss from operations	(15,424)	(23,119)	(56,908)	(60,718)
Other income (expense), net	1,262	1,197	3,323	1,306
Net loss	(14,162)	(21,922)	(53,585)	(59,412)
Other comprehensive income (loss)
Foreign currency translation adjustment	5	20	2	30
Unrealized gain (loss) on marketable securities	0	0	(1)	0
Comprehensive loss	$ (14,157)	$ (21,902)	$ (53,584)	$ (59,382)
Shares used in calculating net loss per common share - basic (in shares)	256,492,558	216,591,011	240,222,667	212,755,746
Shares used in calculating net loss per common share - diluted (in shares)	256,492,558	216,591,011	240,222,667	212,755,746
Net loss per share of common stock - basic (in USD per share)	$ (0.06)	$ (0.10)	$ (0.22)	$ (0.28)
Net loss per share of common stock - diluted (in USD per share)	$ (0.06)	$ (0.10)	$ (0.22)	$ (0.28)