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	$ (7,162)	$ (7,422)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	165	157
Gain on disposal of equipment	0	(44)
Noncash interest expense	0	15
Share-based compensation	1,574	948
ROU asset amortization	270	256
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,313)	1,173
Accounts payable	(611)	0
Accrued expenses	(595)	(442)
Operating lease liability	(270)	(246)
Net cash used in operating activities	(7,942)	(5,605)
Cash flows from investing activities:
Purchases of property and equipment	(194)	(128)
Proceeds from sale of equipment	1	115
Net cash (used in) provided by investing activities	(193)	(13)
Cash flows from financing activities:
Repayment of borrowings under loan	0	(1,875)
Net cash (used in) provided by financing activities	0	(1,875)
Net change in cash, cash equivalents and restricted cash	(8,135)	(7,493)
Cash, cash equivalents and restricted cash at beginning of period	144,514	47,339
Cash, cash equivalents and restricted cash at end of period	136,379	39,846
Supplemental disclosure of cash flow information
Cash paid for interest	0	137
Acquisition of equipment included in accrued expenses	57	161
ROU asset acquired through operating leases	$ 0	$ 5,148