Condensed Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (79,471)	$ (28,080)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	431	258
Stock-based compensation expense	12,540	2,432
Amortization of premiums and discounts on marketable securities, net	87	0
Amortization of discounts and loan issuance costs	0	29
Gain on disposal of property and equipment	(16)	0
Noncash interest expense	0	110
Change in fair value of preferred warrant liability	0	75
Changes in operating assets and liabilities:
Prepaid and other assets	(5,654)	(2,060)
Accounts payable and accrued liabilities	3,869	4,373
Accrued compensation	3,001	818
Operating lease right-of-use assets and liabilities, net	449	121
Deferred revenue	(3,834)	(2,120)
Net cash used in operating activities	(68,598)	(24,044)
Cash flows from investing activities
Maturities of marketable securities	3,580	0
Purchases of property and equipment	(2,033)	(855)
Net cash provided by (used in) investing activities	1,547	(855)
Cash flows from financing activities
Proceeds from issuance of common stock in public offering, gross	165,600	298,080
Payment of issuance costs related to public offering	(10,399)	(24,026)
Proceeds from exercise of stock options, net of repurchases	156	16
Proceeds from issuance of common stock under employee stock purchase plan	318	0
Payments on long-term debt	0	(4,683)
Proceeds from issuance of Series C convertible preferred stock, net of issuance costs	0	2,200
Payment of deferred financing costs	(73)	0
Net cash provided by financing activities	155,602	271,587
Net increase in cash, cash equivalents and restricted cash	88,551	246,688
Cash, cash equivalents and restricted cash at beginning of period	321,713	94,578
Cash, cash equivalents and restricted cash at end of period	410,264	341,266
Supplemental disclosure of cash flow information:
Cash paid for interest	0	571
Supplemental schedule of noncash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	0	676
Costs incurred, but not paid, in connection with public offering included in accounts payable and accrued liabilities	119	0
Costs incurred, but not paid, in connection with deferred financing costs included in accounts payable and accrued liabilities	61	0
Costs incurred, but not paid, in connection with purchases of property and equipment included in accounts payable and accrued liabilities	134	67
Conversion of convertible preferred stock into common stock upon completion of initial public offering	0	136,920
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	$ 0	$ 120