Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities
Net loss	$ (13,057)	$ (8,004)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	222	240
Stock-based compensation expense	620	505
Warrant issuance costs	123
Warrant liability fair value adjustment	(1,228)	(0)
Changes in assets and liabilities
Prepaid expenses and other assets	95	(1,656)
Accounts payable	1,589	443
Deferred revenue	(1,092)	(256)
Accrued and other liabilities	(162)	(1,291)
Net cash used in operating activities	(12,890)	(10,019)
Cash flows from financing activities
Proceeds from issuance of common stock in connection with exercise of options	0	260
Proceeds from issuance of common stock and common stock warrants in direct offering, net of issuance costs	19,168	20,866
Net cash provided by financing activities	19,291	28,160
Net change in cash, cash equivalents, and restricted cash	6,401	18,141
Cash, cash equivalents, and restricted cash at beginning of period	61,855	62,971
Cash, cash equivalents, and restricted cash at end of period	68,256	81,112
At-the-market Offering [Member]
Cash flows from financing activities
Proceeds from issuance of common stock in at the market offering	$ 123	$ 7,034