Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss	$ (35,743)	$ (24,476)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	4,695	1,777
Depreciation	166	150
Amortization of premiums on marketable securities	126	332
Non-cash lease expense	180	314
Other, net	(88)
Change in operating assets and liabilities:
Prepaid expenses and other assets	(308)	(570)
Operating lease right-of-use assets and liabilities	1,612
Accounts payable	(1,342)	762
Accrued expenses	(975)	(434)
Net cash used in operating activities	(31,677)	(22,145)
Cash flows from investing activities:
Purchase of property and equipment	(4,296)	(586)
Purchase of marketable securities	(149,223)	(185,224)
Maturities of marketable securities	99,415	35,360
Net cash used in investing activities	(54,104)	(150,450)
Cash flows from financing activities:
Proceeds from the exercise of stock options and common stock issued under the 2020 ESPP	404	1,418
Net cash provided by financing activities	404	1,418
Net decrease in cash and cash equivalents	(85,377)	(171,177)
Cash, cash equivalents, and restricted cash
Cash, cash equivalents, and restricted cash - beginning of period	173,289	361,422
Cash, cash equivalents, and restricted cash - end of period	87,912	190,245
Supplemental disclosures of noncash investing activities
Accrued purchases of property and equipment	$ 1,501
Supplemental disclosures of cash flow information
Cash paid for income taxes		$ 4