Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (208,018)	$ (338,790)	$ (83,815)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	0	744	1,567
Stock-based compensation	44,833	25,675	7,111
Acquired in-process research and development	0	130,188	0
Gain on sale of in-process research and development asset	0	(16,449)	0
Lease ROU asset and leasehold improvement impairment loss	0	2,580	0
Loss on disposal of long-lived assets	0	915	0
Net (accretion of discount) amortization of premium on marketable securities	(11,404)	(2,318)	(327)
Interest proceeds from maturities of zero coupon debt securities	1,283	0	0
Amortization of operating lease assets	0	220	397
Other	0	15	426
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(2,932)	3,245	(1,144)
Accounts payable	(230)	218	(2,641)
Deferred revenue	0	575	(880)
Development receivables	0	375	440
Operating lease liabilities	0	(2,326)	(435)
Accrued and other liabilities	14,609	(4,891)	(843)
Related party accounts payable	(15,981)	(2,402)	0
Net cash used in operating activities	(157,410)	(99,910)	(80,144)
CASH FLOWS FROM INVESTING ACTIVITIES
Cash assumed from asset acquisition of Spyre	0	3,035	0
Proceeds from sale of in-process research & development asset	0	15,000	0
Purchases of property and equipment	0	0	(38)
Proceeds from the sale of property plant and equipment	0	475	0
Purchases of marketable securities	(599,252)	(166,803)	(39,500)
Proceeds from maturities and sales of marketable securities	245,967	39,900	96,546
Net cash provided by (used in) investing activities	(353,285)	(108,393)	57,008
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of common stock in connection with at-the-market offering program, net of issuance costs	20,521	0	0
Proceeds from issuance of common stock in connection with follow-on offering, net of issuance costs	215,860	0	0
Payment of deferred offering costs in connection with shelf registration	(407)	0	0
Payment of contingent value rights liability	(1,430)	(5,786)	0
Proceeds from issuance of common stock and pre-funded warrants in registered direct offering, net of offering costs	1	0	42,874
Proceeds from employee stock option exercises and employee stock plan purchases	7,511	405	222
Principal payments on finance lease obligation	0	(16)	(418)
Net cash provided by financing activities	410,906	361,077	42,678
Effect of exchange rate on cash, cash equivalents, and restricted cash	(3)	25	(106)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(99,792)	152,799	19,436
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH
Beginning of period	189,215	36,416	16,980
End of period	89,423	189,215	36,416
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Allocation of deferred offering costs against proceeds of issuance of common stock	204	0	0
Settlement of forward contract liability and issuance of Series A non-voting convertible preferred stock in connection with the asset acquisition of Spyre	0	189,741	0
Leased assets obtained in exchange for lease obligations	0	0	21
Reconciliation of Cash, Cash Equivalents, and Restricted Cash Reported in the Statement of Financial Position
Cash and cash equivalents	89,423	188,893	34,863
Restricted cash	0	322	1,553
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	89,423	189,215	36,416
Series A Non-Voting Convertible Preferred Stock
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	(47,624)	(239,158)	0
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of private placement, net	0	197,364	0
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Exchange of Series A non-voting convertible preferred stock for common stock	38,502	0	0
Conversion of non-voting convertible preferred stock into common stock	0	202,178	0
Series B Non-Voting Convertible Preferred Stock
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	(10,839)	(4,749)	0
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of private placement, net	168,850	84,555	0
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Conversion of non-voting convertible preferred stock into common stock	244,010	0	0
Common Stock
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	(149,555)	(94,883)	(83,815)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of private placement, net	0	84,555	0
CVR liability
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liability	20,430	18,986	0
Forward Contract Liability
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liability	$ 0	$ 83,530	$ 0