Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows used in operating activities:
Net loss	$ (83,892)	$ (66,335)	$ (34,099)
Adjustments to reconcile net loss to cash (used in) provided by operating activities:
Stock-based compensation expense	21,512	3,432	1,642
Depreciation and amortization	1,492	1,617	1,595
Accretion of discount (premium) on investments	1,879	(95)	334
Reduction in carrying amount of right-of-use asset	1,415	1,224	1,144
Amortization of debt discount—related party	719	409
Change in fair value of warrant liability		5,676
Gain on disposal of fixed assets			16
Changes in operating assets and liabilities:
Accounts receivable	(1,232)	139	81,815
Prepaid expenses and other current and long-term assets	(6,116)	(3,257)	(814)
Accounts payable	(1,179)	467	4,231
Accrued expenses and other current liabilities	4,377	2,558	3,719
Operating lease liability	(888)	(881)	(734)
Deferred revenue	(25,052)	(12,203)	(3,235)
Net cash (used in) provided by operating activities	(86,965)	(67,249)	55,614
Cash flows used in investing activities:
Proceeds from maturities of marketable securities	349,681	104,000	78,666
Purchase of marketable securities	(537,740)	(293,855)	(79,000)
Purchases of property and equipment	(1,277)	(650)	(1,349)
Proceeds from sale of property and equipment			63
Net cash used in investing activities	(189,336)	(190,505)	(1,620)
Cash flows provided by financing activities:
Proceeds from follow-on offering, net of issuance costs paid of $11.3 million	169,465
Proceeds from exercises of stock options	2,330	887	274
Proceeds from initial public offering, net of underwriting discount of $14.7 million		195,074
Payment of initial public offering costs	(286)	(3,606)
Proceeds from issuance of Series B shares, net of issuance costs of $4.5 million		145,525
Proceeds from long-term debt and warrant—related party, net of issuance costs of $0.5 million		11,973
Repurchase of common stock		(194)	(30)
Vested stock option settlement		(727)
Other	(109)
Net cash provided by financing activities	171,400	348,932	244
Net change in cash, cash equivalents and restricted cash	(104,901)	91,178	54,238
Cash, cash equivalents and restricted cash at beginning of period	184,304	93,126	38,888
Cash, cash equivalents and restricted cash at end of period	79,403	184,304	93,126
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents and restricted cash at end of period	79,403	184,304	93,126
Less: restricted cash	(3,279)	(2,577)	(2,577)
Cash and cash equivalents at end of the year	76,124	181,727	90,549
Supplemental disclosure of cash flow information:
Cash paid for interest	1,308	820
Cash paid for taxes		143	1,088
Supplemental disclosures of non-cash investing and financing activities:
Operating lease liabilities arising from obtaining right-of-use assets	$ 20,131
Conversion of redeemable convertible preferred stock to common stock upon closing of the initial public offering		256,520
Warrant liability reclassification to equity		8,001
Initial public offering costs in accounts payable and accrued expenses		$ 296
Capital expenditures in accounts payable			172
Stock option repurchases included in accrued expenses			$ 16