Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss	$ (33,825,000)	$ (25,647,000)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation of equipment	15,000	5,000
Stock-based compensation	2,823,000	2,018,000
Amortization of premiums and discounts on marketable securities	438,000	234,000
Net loss on sale of marketable securities	70,000
Amortization of right of use lease asset	207,000	207,000
Accretion of lease liability	28,000	37,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	6,740,000	(182,000)
Other assets, non-current	(981,000)	(841,000)
Accounts payable	1,284,000	(1,266,000)
Accrued expenses and other current liabilities	1,790,000	376,000
Operating lease liabilities	(226,000)	(261,000)
Net cash used in operating activities	(21,637,000)	(25,320,000)
Cash flows from investing activities:
Purchases of marketable securities	(40,656,000)	(81,051,000)
Proceeds from sale of marketable securities	30,415,000	11,724,000
Purchases of property and equipment	(17,000)	(180,000)
Net cash used in investing activities	(10,258,000)	(69,507,000)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	18,000
Net cash provided by financing activities	18,000
Net decrease in cash, cash equivalents and restricted cash	(31,877,000)	(94,827,000)
Effect of exchange rate changes on cash and cash equivalents	(891,000)	(371,000)
Cash and cash equivalents, beginning of period	62,563,000	163,836,000
Cash and cash equivalents, end of period	$ 29,795,000	68,638,000
Supplemental disclosures of cash flow information:
Cash paid for taxes		42,000
Supplemental disclosures of noncash activities:
Operating lease liabilities arising from obtaining right-of-use assets		$ 409,000