Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Consolidated net loss	$ (12,154)	$ (7,155)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	81	121
Stock-based compensation	417	360
Amortization of premium of available-for-sale investment securities	237	51
Amortization of right-of-use assets	217	176
Gain on disposal of property and equipment	(89)
Changes in operating assets and liabilities:
Other receivables	9	1,950
Prepaid expenses and other assets	1,180	395
Accounts payable and accrued expenses	216	(1,521)
Operating lease liability	(233)	(204)
Net cash used in operating activities	(10,119)	(5,827)
Cash flows from investing activities:
Purchases of property and equipment	(43)	(17)
Purchases of available-for-sale investment securities		(25,678)
Maturities of available-for-sale investment securities	14,500	2,300
Proceeds from sale of property and equipment	169
Net cash provided by (used in) investing activities	14,626	(23,395)
Cash flows from financing activities:
Proceeds from issuance of common stock through option exercises	1
Proceeds from issuance of common stock from at-the-market offerings, net of offering costs	1,480	9,621
Proceeds from issuance of common stock from committed purchase agreement, net of offering costs		15,236
Net cash provided by financing activities	1,481	24,857
Net change in cash and cash equivalents	5,988	(4,365)
Cash and cash equivalents at beginning of period	2,336	16,952
Cash and cash equivalents at the end of period	$ 8,324	$ 12,587