STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (16,509)	$ (8,872)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	229	250
Stock-based compensation expense	2,744	527
Amortization of discount on investments, net	441
Changes in operating assets and liabilities:
Prepaid expenses and other assets	1,432	53
Accounts payable and accrued other liabilities	(3,238)	(237)
Net cash used in operating activities	(14,901)	(8,279)
Cash flows from investing activities:
Acquisitions of property and equipment	(182)	(4)
Purchases of investments	(25,171)
Sales and maturities of investments	66,000
Proceeds from notes receivable		193
Net cash provided by investing activities	40,647	189
Cash flows from financing activities:
Payment of deferred offering costs		(1,639)
Proceeds from stock option exercises	16	12
Net cash provided by (used in) financing activities	16	(1,627)
Net increase (decrease) in cash and cash equivalents	25,762	(9,717)
Cash and cash equivalents, beginning of period	78,446	89,159
Cash and cash equivalents, end of period	104,208	79,442
Supplemental disclosure of non-cash investing and financing activities:
Amounts accrued for purchase of property and equipment	$ 78	101
Unpaid deferred offering costs		$ 675