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	$ (32,081)	$ (24,402)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	86	48
Net accretion of discounts/premiums on debt securities	109	0
Stock-based compensation	4,701	1,061
Loss on investment in joint venture	728	950
Changes in operating assets and liabilities:
Prepaid expenses, right-of-use assets and other assets	(1,308)	(2,249)
Accounts payable	23	787
Accrued expenses and operating lease liability	457	(970)
Net cash used in operating activities	(27,285)	(24,775)
Cash Flows used in Investing Activities:
Purchases of marketable securities	(109,096)	0
Proceeds from maturities of marketable securities	22,000	0
Purchase of property and equipment	(50)	(66)
Investment in joint venture	(150)	(2,000)
Net cash used in investing activities	(87,296)	(2,066)
Cash Flows from Financing Activities:
Payments of offering costs	0	(663)
Net cash used by financing activities	0	(663)
Net decrease in cash and cash equivalents	(114,581)	(27,504)
Cash and cash equivalents - beginning of period	175,334	140,233
Cash and cash equivalents - end of period	60,753	112,729
Supplemental Disclosures of Noncash Investing and Financing Activities:
Offering costs in accounts payable and accrued expenses	0	1,762
Property and equipment in accounts payable and accrued expenses	$ 6	$ 15