Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (31,934,000)	$ (23,476,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	112,000	109,000
Stock-based compensation	3,415,000	2,772,000
Amortization of debt issuance costs	265,000	25,000
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(234,000)	(23,000)
(Increase) decrease in prepaid expenses and other current assets	(867,000)	273,000
Decrease in other assets	400,000	207,000
Decrease in accounts payable and other liabilities	(2,770,000)	(3,308,000)
Net cash provided by (used in) operating activities	(31,613,000)	(23,421,000)
Cash and cash equivalents	26,001,000	59,520,000
Cash paid for interest	1,556,000	85,000
Issuance of Stock and Warrants for Services or Claims	0
Adjustments to Additional Paid in Capital, Warrant Issued		698
Treasury Stock, Carrying Basis		6,321
Stock Issued During Period, Value, Treasury Stock Reissued	0	0
Business Exit Costs	0	1,500
Issuance of common stock under Equity Incentive Plans, value		864,000
Cash flows from investing activities:
Purchases of property and equipment	(248,000)	(76,000)
Purchases of investments	(28,864,000)	(17,816,000)
Maturities of investments	41,205,000	13,484,000
Net cash (used in) provided by investing activities	12,093,000	(4,408,000)
Cash flows from financing activities:
Repurchase of common stock	(824,000)	(864,000)
Proceeds from debt borrowings, net of fees	0	24,148,000
Net cash used in financing activities	(824,000)	23,284,000
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(20,344,000)	(4,545,000)
Cash and cash equivalents at beginning of period	46,345,000	64,065,000
Cash and cash equivalents at end of period	26,001,000	59,520,000
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 1,556,000	$ 85,000