STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (9,788)	$ (21,554)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	689	540
Amortization of financing costs	198	0
Stock-based compensation	853	2,197
(Increase) decrease in:
Receivables	1,111	(340)
Prepaid expenses and other current assets	149	3,207
Right of use asset	180	292
Other noncurrent assets	5	559
Increase (decrease) in:
Accounts payable	(763)	2,654
Accrued expenses	(214)	(2,684)
Lease liabilities	(190)	(184)
Net cash used in operating activities	(7,770)	(15,313)
Cash flows from investing activities:
Purchases of property and equipment	(29)	(717)
Net cash used in investing activities	(29)	(717)
Cash flows from financing activities:
Proceeds from exercise of stock options	0	1,017
Net cash provided by financing activities	0	1,017
Net decrease in cash and cash equivalents	(7,799)	(15,013)
Cash and cash equivalents, and restricted cash, beginning of period	76,054	115,069
Cash and cash equivalents, and restricted cash, end of period	68,255	100,056
Supplementary disclosure of cash flow information:
Cash paid for interest	484	0
Amounts included in accrued expenses and accounts payable related to property and equipment	$ 29	$ 682