Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (192,410)	$ (140,241)	$ (72,273)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	2,270	842	147
Stock-based compensation expense	30,621	18,368	11,686
Amortization of right-of-use operating lease assets	1,318	5,036	1,844
Change in fair value of CVR liability	(1,700)	(1,360)	(343)
Net amortization (accretion) of premiums (discounts) on marketable securities	(5,173)	(1,638)	0
Loss on disposal of property and equipment	8	0	0
Right-of-use asset impairment	0	(396)	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(626)	(1,486)	(227)
Other assets	(119)	(1,018)	(3,727)
Accounts payable	4,813	2,359	2,751
Accrued expenses and other current liabilities	8,170	9,586	3,431
Operating lease liability	(796)	(8,690)	(2,052)
Net cash used in operating activities	(153,624)	(118,638)	(58,763)
Cash flows from investing activities:
Purchases of property and equipment	(2,796)	(6,863)	(1,719)
Purchases of marketable securities	(348,803)	(177,855)	0
Maturities and sales of marketable securities	253,775	60,000	0
Net cash used in investing activities	(97,824)	(124,718)	(1,719)
Cash flows from financing activities:
Proceeds from issuance of shares of common stock, net of offering costs of $10.7 million	161,819	0	0
Proceeds from issuance of shares of common stock and pre-funded warrants, net of offering costs of $10.8 million	0	161,945	0
Proceeds from issuance of common stock under ATM, net of issuance costs of $1.2 million	0	0	38,006
Proceeds from issuance of common stock upon stock option exercises	965	1,238	24
Proceeds from pre-funded warrant exercises	0	24	0
Proceeds from issuance of stock from employee stock purchase plan	752	351	31
Payments to CVR Holders	0	0	(85)
Net cash provided by financing activities	163,536	163,558	37,976
Net decrease in cash, cash equivalents and restricted cash	(87,912)	(79,798)	(22,506)
Cash, cash equivalents and restricted cash at beginning of period	141,141	220,939	243,445
Cash, cash equivalents and restricted cash at end of period	53,229	141,141	220,939
Supplemental disclosure of cash flow information:
Right-of-use assets obtained in exchange for new operating lease liabilities	0	25,184	0
Supplemental disclosure of noncash investing and financing information:
Conversion of Series A non-voting convertible preferred stock into common stock	5,795	19,570	25,481
Offering costs included in accounts payable and accrued expenses	30	30	0
Property & equipment included in accounts payable and accrued expenses	43	58	0
Issuance of common shares in partial settlement of CVR liability	$ 0	$ 0	$ 2,043