Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows used in operating activities:
Net loss	$ (132,493)	$ (128,175)
Adjustments to reconcile net loss to cash used in operating activities:
Stock-based compensation expense	27,235	30,016
Depreciation and amortization	1,880	1,676
Reduction in carrying amount of right-of-use asset	6,159	5,896
Accretion of (premium) discount on marketable securities	(3,784)	714
Amortization of debt discount—related party	405	713
Loss on early extinguishment of debt	621	0
Other	77	0
Changes in operating assets and liabilities:
Accounts receivable	(10,327)	4,244
Prepaid expenses and other current and long-term assets	2,723	388
Accounts payable	273	(3,333)
Accrued expenses and other current liabilities	1,316	5,083
Operating lease liability	(4,695)	(507)
Deferred revenue	3,772	(22,654)
Net cash used in operating activities	(106,838)	(105,939)
Cash flows provided by investing activities:
Proceeds from maturities of marketable securities	289,955	283,445
Purchase of marketable securities	(129,898)	(219,527)
Purchases of property and equipment	(1,708)	(5,496)
Net cash provided by investing activities	158,349	58,422
Cash flows provided by financing activities:
Proceeds from issuance of common stock pursuant to the at-the-market equity program, net	57,673	0
Payment of long-term debt − related party	(12,500)	0
Proceeds from exercises of stock options	58	777
Payments for repurchase of common stock for tax withholding	(110)	0
Other	368	370
Net cash provided by financing activities	45,489	1,147
Net change in cash, cash equivalents and restricted cash	97,000	(46,370)
Cash, cash equivalents and restricted cash at beginning of period	33,033	79,403
Cash, cash equivalents and restricted cash at end of period	130,033	33,033
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents and restricted cash at end of year	130,033	33,033
Less: restricted cash	(3,443)	(3,279)
Cash and cash equivalents at end of the year	126,590	29,754
Supplemental disclosure of cash flow information:
Deferred revenue in accounts receivable	10,000	0
Cash paid for interest - related party	990	1,624
Cash paid for income taxes	1,003	0
Supplemental disclosures of non-cash investing and financing activities:
Capital expenditures in accounts payable and accrued expenses	18	473
Operating lease liabilities arising from obtaining right-of-use assets	$ 0	$ 44,067