STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (78,715)	$ (73,703)	$ (26,883)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	897	970	1,028
Stock-based compensation expense	12,853	5,278	1,094
Non-cash stock consideration, acquisition	0	19,843	0
Loss on fixed asset disposals	2		8
Amortization of discount on investments, net	1,349	299	0
Changes in operating assets and liabilities:
Prepaid expenses and other assets	1,142	(2,258)	234
Accounts payable and accrued other liabilities	2,931	4,303	986
Net cash used in operating activities	(59,541)	(45,268)	(23,533)
Cash flows from investing activities:
Acquisitions of property and equipment	(939)	(667)	(768)
Purchases of investments	(69,626)	(225,485)
Sales and maturities of investments	229,000	10,000
Proceeds from notes receivable	0	193
Net cash used in investing activities	158,435	(215,959)	(768)
Cash flows from financing activities:
Proceeds from issuance of common stock	50,000	271,308
Issuance costs associated with financings	(1,852)	(21,237)	(99)
Proceeds from issuance of preferred stock, net of issuance costs	0	0	70,792
Proceeds from stock option exercises	986	443	131
Net cash provided by financing activities	49,134	250,514	70,824
Net (decrease) increase in cash and cash equivalents	148,028	(10,713)	46,523
Cash and cash equivalents, beginning of period	78,446	89,159	42,636
Cash and cash equivalents, end of period	226,474	78,446	89,159
Supplemental disclosure of non-cash investing and financing activities:
Amounts accrued for purchase of property and equipment	436	43
Conversion of preferred stock to common stock	0	178,058
Unpaid deferred financing costs	$ 0	$ 0	$ 1,244