Condensed Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock [Member]	Series A-1 Convertible Preferred Stock [Member]	Series B Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss
Opening balance at Dec. 31, 2019	$ (11,420)	$ 1,067	$ 16,333			$ 8,220	$ (19,640)
Opening balance (Shares) at Dec. 31, 2019		477,297	7,537,879		419,124
Share-based compensation	116					116
Net loss	(6,570)						(6,570)
Closing balance at Sep. 30, 2020	(17,874)	$ 1,067	$ 16,333			8,336	(26,210)
Closing balance (Shares) at Sep. 30, 2020		477,297	7,537,879		419,124
Opening balance at Jun. 30, 2020	(15,423)	$ 1,067	$ 16,333			8,297	(23,720)
Opening balance (Shares) at Jun. 30, 2020		477,297	7,537,879		419,124
Share-based compensation	39					39
Net loss	(2,490)						(2,490)
Closing balance at Sep. 30, 2020	(17,874)	$ 1,067	$ 16,333			8,336	(26,210)
Closing balance (Shares) at Sep. 30, 2020		477,297	7,537,879		419,124
Opening balance at Dec. 31, 2020	(18,591)	$ 1,067	$ 16,333	$ 39,253		8,374	(26,965)
Opening balance (Shares) at Dec. 31, 2020		477,297	7,537,879	11,862,043	419,124
Issuance of milestone shares for cash, net of issuance costs				$ 30,031
Issuance of milestone shares for cash, net of issuance costs (Shares)				7,908,027
Exercise of preferred stock warrant			$ 1,250
Exercise of preferred stock warrant (shares)			447,426
Reclassification of preferred stock tranche rights liability upon issuance of milestone shares				$ 81,190
Reclassification of warrant liability upon exercise of preferred stock warrant	5,380		$ 5,380
Exercise of common stock warrants	614					614
Exercise of common stock warrants (Shares)					137,446
Conversion of convertible preferred stock into common stock upon initial public offering	174,504	$ (1,067)	$ (22,963)	$ (150,474)	$ 3	174,501
Conversion of convertible preferred stock into common stock upon initial public offering, Shares		(477,297)	(7,985,305)	(19,770,070)	28,232,672
Issuance of common stock for cash, net of issuance costs of $15,441	168,559				$ 1	168,558
Issuance of common stock for cash, net of issuance costs of $15,441, Shares					11,499,998
Cashless exercise of common stock warrants					178,847
Stock options exercised	$ 2					2
Stock options exercised, Shares	2,236				2,236
Unrealized loss on marketable securities	$ (28)							$ (28)
Share-based compensation	557					557
Net loss	(92,257)						(92,257)
Closing balance at Sep. 30, 2021	233,360	$ 0	$ 0	$ 0	$ 4	352,606	(119,222)	(28)
Closing balance (Shares) at Sep. 30, 2021		0	0	0	40,470,323
Opening balance at Jun. 30, 2021	(106,079)	$ 1,067	$ 22,963	$ 150,474	$ 0	9,241	(115,320)
Opening balance (Shares) at Jun. 30, 2021		477,297	7,985,305	19,770,070	556,570
Conversion of convertible preferred stock into common stock upon initial public offering	174,504	$ (1,067)	$ (22,963)	$ (150,474)	$ 3	174,501
Conversion of convertible preferred stock into common stock upon initial public offering, Shares		(477,297)	(7,985,305)	(19,770,070)	28,232,672
Issuance of common stock for cash, net of issuance costs of $15,441	168,559				$ 1	168,558
Issuance of common stock for cash, net of issuance costs of $15,441, Shares					11,499,998
Cashless exercise of common stock warrants					178,847
Stock options exercised	2					2
Stock options exercised, Shares					2,236
Unrealized loss on marketable securities	(28)							(28)
Share-based compensation	304					304
Net loss	(3,902)						(3,902)
Closing balance at Sep. 30, 2021	$ 233,360	$ 0	$ 0	$ 0	$ 4	$ 352,606	$ (119,222)	$ (28)
Closing balance (Shares) at Sep. 30, 2021		0	0	0	40,470,323