Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (97,505)	$ (30,788)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	11,529	2,376
Depreciation and amortization expense	747	483
Non-cash lease expense	(28)
Amortization (accretion) of premium (discount) on marketable securities	1,843
Changes in success fee obligation		450
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(12,816)	(107)
Right-of-use assets	(2,940)
Accounts payable and other liabilities	7,675	1,114
Net cash used in operating activities	(91,495)	(26,472)
Cash flows from investing activities:
Purchases of property and equipment	(1,628)	(438)
Purchases of marketable securities	(208,207)
Maturities of marketable securities	72,178
Net cash used in investing activities	(137,657)	(438)
Cash flows from financing activities:
Proceeds from initial public offering of common stock, net of issuance costs		247,454
Proceeds from follow-on public offering of common stock, net of issuance costs	157,237
Proceeds from issuance of debt, net of issuance costs		9,936
Settlement of success fee obligation		(450)
Proceeds from issuance of convertible preferred stock, net of issuance costs	0	134,920
Proceeds from exercise of stock options	495	24
Net cash provided by financing activities	157,732	391,884
Net increase (decrease) in cash and cash equivalents	(71,420)	364,974
Cash, cash equivalents and restricted cash, beginning of period	303,153	14,632
Cash, cash equivalents and restricted cash, end of period	231,733	379,606
Supplemental cash flow information:
Cash paid for interest and taxes		311
Supplemental disclosures of cash flow information:
Purchase of property and equipment in accounts payable	161
Right-of-use assets acquired under operating leases	33,799
Issuance costs from convertible preferred stock included in accounts payable or accrued expenses	$ 0	134
Conversion of convertible preferred stock to common stock		162,215
Public offering costs included in accounts payable or accrued expenses		$ 1,043