Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (7,329)	$ (8,371)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	11	13
Change in fair value of term loan derivative liability	11	6
Accretion/accrual of term loan discounts and debt issuance costs	154	145
Stock-based compensation	737	718
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	420	679
Accounts payable	(1,110)	(1,215)
Accrued expenses and other liabilities	14	447
Net cash used in operating activities	(7,092)	(7,578)
Financing activities:
Repayments of term loan	(583)
Proceeds from at-the-market sales, net of commissions		4,178
Proceeds from exercises of warrants	2
Payments of offering costs	(44)	(31)
Net cash (used in) provided by financing activities	(625)	4,147
Net decrease in cash and cash equivalents	(7,717)	(3,431)
Cash and cash equivalents at beginning of period	36,830	45,001
Cash and cash equivalents at end of period	$ 29,113	$ 41,570