CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net (loss) income	$ (7,757)	$ (33,294)
Adjustments to reconcile net (loss) income to cash flows from operating activities:
Depreciation	3	2
Deferred tax assets	(685)	(4,477)
Amortization of warrant issuance costs	0	34
Stock-based compensation	1,590	1,853
Changes in assets and liabilities:
Accounts receivables	(2)	(6)
Prepaid expenses and other assets	(134)	(46)
Accounts payable	12	(209)
Accrued payroll and related expenses	63	86
Accrued licensing costs	(355)	(9,438)
Other liabilities	(31)	(24)
Net cash (used in) operating activities	(7,296)	(45,519)
Cash flows from investing activities:
Purchase of investments	(13,203)	(7,817)
Proceeds from sale or maturity of investments	5,688	14,256
Net cash (used in) provided by investing activities	(7,515)	6,439
Cash flows from financing activities:
Payment of payroll taxes on vested restricted stock units	(29)	(196)
Net cash used in financing activities	(29)	(196)
Net change in cash and cash equivalents	(14,840)	(39,276)
Cash and cash equivalents, beginning of period	142,018	192,908
Cash and cash equivalents, end of period	127,178	153,632
Cash paid for income taxes	$ 2	$ 0