Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net income (loss)	$ (19,741)	$ 6,199
Adjustments to reconcile net income (loss) to net cash provided by (used in)    operating activities:
Depreciation and amortization expense	318	345
Stock-based compensation expense	1,646	1,865
Non-cash interest expense related to note payable	122	146
Net amortization of premiums and discounts on marketable securities	(134)	178
Loss on disposal of property and equipment	3	0
Non-cash operating lease cost	614	614
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(837)	(695)
Unbilled receivable	0	(30,000)
Other assets	2	(20)
Accounts payable	852	1,074
Accrued expenses and other current liabilities	(5,582)	(2,601)
Operating lease liability	(702)	(671)
Net cash used in operating activities	(23,439)	(23,566)
Cash flows from investing activities:
Purchases of property and equipment	(17)	(35)
Proceeds from sales of property and equipment	31	0
Purchases of marketable securities	(16,930)	0
Proceeds from sales or maturities of marketable securities	18,350	12,500
Net cash provided by investing activities	1,434	12,465
Cash flows from financing activities:
Proceeds from issuance of common stock upon public offering, net	0	20,556
Proceeds from employee stock purchases	77	157
Net cash provided by financing activities	77	20,713
Net increase (decrease) in cash and cash equivalents and restricted cash	(21,928)	9,612
Cash and cash equivalents and restricted cash at beginning of period	52,505	57,640
Cash and cash equivalents and restricted cash at end of period	30,577	67,252
Supplemental disclosure of cash flow information:
Cash paid for interest	1,746	531
Supplemental disclosure of non-cash investing and financing activities:
Additional right-of-use asset and related lease liability	0	755
Purchases of property and equipment included in accounts payable and accrued expenses	$ 66	$ 43