Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 0	$ 0	$ 0	$ 0
Operating expenses:
Research and development	4,278	2,684	12,447	9,241
General and administrative	2,513	2,344	7,342	7,063
Total operating expenses	6,791	5,028	19,789	16,304
Loss from operations	(6,791)	(5,028)	(19,789)	(16,304)
Interest income	21	5	54	77
Other income, net	66		370	66
Net loss	$ (6,704)	$ (5,023)	$ (19,365)	$ (16,161)
Net loss per share — basic and diluted	$ (0.07)	$ (0.13)	$ (0.22)	$ (0.49)
Weighted average common shares outstanding—basic and diluted	90,548,972	39,321,177	88,211,362	32,808,082
Comprehensive loss:
Net loss	$ (6,704)	$ (5,023)	$ (19,365)	$ (16,161)
Other comprehensive loss:
Unrealized gain (loss) on investments, net of tax of $0	(5)	1	3	(8)
Total other comprehensive gain (loss)	(5)	1	3	(8)
Total comprehensive loss	$ (6,709)	$ (5,022)	$ (19,362)	$ (16,169)