Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (8,066)	$ (7,562)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	559	599
Depreciation and amortization expense	3	5
Change in fair value of warrant derivative and private placement option liabilities	(574)	1,637
Changes in operating assets and liabilities:
Accounts receivable, interest and other receivables	(8)	(2)
Prepaid expenses and other assets	138	(674)
Accounts payable	740	122
Accrued liabilities and other	778	(502)
Net cash used in operating activities	(6,430)	(6,377)
Cash flows from investing activities:
Purchases of property and equipment	(5)	(7)
Net cash used in investing activities	(5)	(7)
Effect of exchange rate changes on cash	0	(3)
Net change in cash, cash equivalents, and restricted cash	(6,435)	(6,387)
Cash, cash equivalents and restricted cash at beginning of period	21,837	$ 47,657
Cash, cash equivalents and restricted cash at end of period	$ 15,402