Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (155,203,000)	$ (208,018,000)	$ (338,790,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	0	0	744,000
Stock-based compensation	37,614,000	44,833,000	25,675,000
Acquired in-process research and development	0	0	130,188,000
Gain on sale of in-process research and development asset	(10,000,000)	0	(16,449,000)
Lease ROU asset and leasehold improvement impairment loss	0	0	2,580,000
Loss on disposal of long-lived assets	0	0	915,000
Net (accretion of discount) amortization of premium on marketable securities	(8,090,000)	(11,404,000)	(2,318,000)
Interest proceeds from maturities of zero coupon debt securities	2,130,000	1,283,000	0
Amortization of operating lease assets	0	0	220,000
Other	0	0	15,000
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(12,819,000)	(2,932,000)	3,245,000
Accounts payable	8,238,000	(230,000)	218,000
Deferred revenue	0	0	575,000
Development receivables	0	0	375,000
Operating lease liabilities	0	0	(2,326,000)
Accrued and other liabilities	(764,000)	14,609,000	(4,891,000)
Related party accounts payable	(589,000)	(15,981,000)	(2,402,000)
Net cash used in operating activities	(169,252,000)	(157,410,000)	(99,910,000)
CASH FLOWS FROM INVESTING ACTIVITIES
Cash assumed from asset acquisition of Spyre	0	0	3,035,000
Proceeds from sale of in-process research & development asset	7,000,000	0	15,000,000
Proceeds from the sale of property plant and equipment	0	0	475,000
Purchases of marketable securities	(522,214,000)	(599,252,000)	(166,803,000)
Proceeds from maturities and sales of marketable securities	371,739,000	245,967,000	39,900,000
Net cash (used in) provided by investing activities	(143,475,000)	(353,285,000)	(108,393,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of common stock in connection with at-the-market offering program, net of issuance costs	14,750,000	20,521,000	0
Proceeds from issuance of common stock in connection with follow-on offering, net of issuance costs	296,382,000	215,860,000	0
Payment of deferred offering costs in connection with shelf registration	(162,000)	(407,000)	0
Payment of contingent value rights liability	(5,251,000)	(1,430,000)	(5,786,000)
Proceeds from employee stock option exercises and employee stock plan purchases	3,306,000	7,511,000	405,000
Other financing cash flows	0	1,000	(16,000)
Net cash provided by financing activities	309,025,000	410,906,000	361,077,000
Effect of exchange rate on cash, cash equivalents, and restricted cash	0	(3,000)	25,000
NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(3,702,000)	(99,792,000)	152,799,000
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH
Beginning of period	89,423,000	189,215,000	36,416,000
End of period	85,721,000	89,423,000	189,215,000
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Allocation of deferred offering costs against proceeds of issuance of common stock	107,000	204,000	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	0	189,741,000
Reconciliation of Cash, Cash Equivalents, and Restricted Cash Reported in the Statement of Financial Position
Cash and cash equivalents	85,721,000	89,423,000	188,893,000
Restricted cash	0	0	322,000
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	85,721,000	89,423,000	189,215,000
Series B Non-Voting Convertible Preferred Stock
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	(1,317,000)	(10,839,000)	(4,749,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of private placement, net	0	168,850,000	84,555,000
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Conversion of non-voting convertible preferred stock into common stock	0	244,010,000	0
Series A Non-Voting Convertible Preferred Stock
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	(27,344,000)	(47,624,000)	(239,158,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of private placement, net	0	0	197,364,000
Supplemental Disclosure of Non-Cash Investing and Financing Information:
Exchange of Series A non-voting convertible preferred stock for common stock	0	38,502,000	0
Conversion of non-voting convertible preferred stock into common stock	0	0	202,178,000
Common Stock
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	(126,541,000)	(149,555,000)	(94,883,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of private placement, net	0	0	84,555,000
CVR Liability
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liability	(29,769,000)	20,430,000	18,986,000
Forward Contract Liability
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liability	$ 0	$ 0	$ 83,530,000