Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Cash Flows Used in Operating Activities
Net loss	$ (13,835)	$ (20,395)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	64	73
Accretion of discounts on investments		3
Stock-based compensation	1,180	2,695
Gain on remeasurement of the lease liability		(362)
Non-cash lease expense	273	351
Changes in operating assets and liabilities:
Receivables	(127)	513
Prepaid expenses and other current assets	(146)	(619)
Accounts payable	(1,526)	(390)
Accrued liabilities	(1,560)	(3,402)
Lease liability	(333)	(469)
Net cash used in operating activities	(16,010)	(22,002)	$ (66,300)
Cash Flows Provided by Investing Activities
Proceeds from sale and maturity of investments		6,500
Net cash provided by investing activities		6,500
Cash Flows Provided by Financing Activities
Proceeds from issuance of common stock through an at-the-market offering, net	1,137	9,535
Proceeds from stock options exercises		2
Net cash provided by financing activities	1,137	9,537
Net decrease in cash, cash equivalents, and restricted cash	(14,873)	(5,965)
Cash, cash equivalents, and restricted cash at beginning of period	59,807	107,586	107,586
Cash, cash equivalents, and restricted cash at end of period	44,934	101,621	$ 59,807
Supplemental Disclosure of Non-Cash Activities:
Unpaid amounts related to stock issuance and deferred financing costs	$ 417	$ 47