Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net loss	$ (33,940)	$ (32,758)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	50	47
Change in fair value of term loan derivative liability	(82)	9
Accretion/accrual of term loan discounts and debt issuance costs	599	227
Other expense related to transaction with Lincoln Park Capital Fund, LLC	375
Stock-based compensation	2,543	2,417
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	342	742
Accounts payable	831	417
Accrued expenses and other liabilities	336	(101)
Net cash used in operating activities	(28,946)	(29,000)
Investing activities:
Purchases of property, equipment and leasehold improvements		(32)
Net cash used in investing activities		(32)
Financing activities:
Proceeds from term loan		14,000
Payments of financing costs of term loan	(68)	(84)
Proceeds from at-the-market sales, net of commissions	7,505	3,135
Proceeds from exercises of stock options		34
Proceeds from employee stock purchase plan	39	12
Proceeds from exercises of warrants	3
Proceeds from sale of common stock and warrants under private placement, net of issuance costs	13,678
Payments of offering costs	(382)	(377)
Net cash provided by financing activities	20,775	16,720
Net decrease in cash and cash equivalents	(8,171)	(12,312)
Cash and cash equivalents at beginning of period	45,001	57,313
Cash and cash equivalents at end of period	36,830	45,001
Supplemental disclosure of cash flow information:
Interest paid	603	180
State research tax credits exchanged for cash	18	18
Supplemental disclosure of non-cash financing activities:
Offering costs included in accrued expenses	$ 41	$ 11