CONDENSED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses:
Research and development	$ 3,507	$ 4,766	$ 14,271	$ 19,655
General and administrative	2,331	2,718	7,959	8,992
Restructuring costs	130		1,322
Total operating expenses	5,968	7,484	23,552	28,647
Loss from operations	(5,968)	(7,484)	(23,552)	(28,647)
Other income (expense):
Interest income	2	9	7	161
Interest expense			(7)
Warrant revaluation gain		(683)	6,983	(495)
Future tranche right revaluation gain		(12,350)	118,803	(6,988)
Foreign currency exchange (loss) gain	1	(44)	(24)	8
Net income / (loss)	(5,965)	(20,552)	102,210	(35,961)
Net income (loss) applicable to common stockholders (Note 12)
Basic	(5,965)	(20,552)	100,574	(35,961)
Diluted	$ (5,965)	$ (20,552)	$ (23,576)	$ (35,961)
Net income (loss) per share applicable to common stockholders (Note 12)
Basic	$ (0.11)	$ (0.59)	$ 2.10	$ (1.09)
Diluted	$ (0.11)	$ (0.59)	$ (0.46)	$ (1.09)
Weighted-average number of common shares used in computing net income (loss) per share applicable to common stockholders
Basic	52,740	35,091	47,990	32,999
Diluted	52,740	35,091	51,613	32,999