CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series A, B, C and D Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balances at Dec. 31, 2020	$ 132,040	$ 3	$ 29	$ 409,722	$ (277,707)	$ (7)
Balances, Shares at Dec. 31, 2020		3,218,287	29,260,247
Issuance of common stock upon the exercise of stock options	93			93
Issuance of common stock upon the exercise of stock options, shares			11,514
Issuance of common stock, net of financing/offering costs and net of issuance costs	4,123		$ 1	4,122
Issuance of common stock and preferred stock, net of financing/offering costs, shares			257,185
Conversion of convertible preferred stock to common stock, shares		135	(135,000)
Share-based compensation expense	2,009			2,009
Unrealized gain (loss) on available-for-sale securities	4					4
Net loss	(19,423)				(19,423)
Balances at Mar. 31, 2021	118,846	$ 3	$ 30	415,946	(297,130)	(3)
Balances, Shares at Mar. 31, 2021		3,218,152	29,663,946
Balances at Dec. 31, 2021	88,289	$ 3	$ 32	455,719	(367,463)	(2)
Balances, Shares at Dec. 31, 2021		3,218,152	32,393,738
Issuance of common stock upon the exercise of stock options	$ 188			188
Issuance of common stock upon the exercise of stock options, shares	17,616		17,616
Issuance of common stock, net of financing/offering costs and net of issuance costs	$ 3,626		$ 1	3,625
Issuance of common stock and preferred stock, net of financing/offering costs, shares			344,205
Share-based compensation expense	3,203			3,203
Unrealized gain (loss) on available-for-sale securities	(4)					(4)
Net loss	(32,829)				(32,829)
Balances at Mar. 31, 2022	$ 62,473	$ 3	$ 33	$ 462,735	$ (400,292)	$ (6)
Balances, Shares at Mar. 31, 2022		3,218,152	32,755,559