Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Cash flows from operating activities:
Net loss			$ (33,440)	$ (47,141)
Adjustments to reconcile net loss to net cash used in operations:
Royalty obligation expense - related party				32,044
Depreciation expense			3
Stock-based compensation expense			1,603	615
Capital contributions - in-kind services - related party				60
Change in fair value of derivative liabilities (including $1,165 and $860 for a related party)	$ 0	$ (549)	(1,229)	(860)
Change in fair value of tranche liability (including $331 and $0 for a related party)	0	0	(365)	0
Non-cash interest expense (including $1,384 and $1,392 for a related party)			1,443	1,392
Non-cash operating lease expense			12
Net amortization of premiums and accretion of discounts on investments			(83)
Loss on extinguishment and on issuance of convertible promissory notes (including $169 and $2,134 for a related party)			186	2,134
Changes in assets and liabilities:
Prepaid expense and other current assets			1,453	(70)
Other non-current assets			(370)	(314)
Accounts payable			(962)	(129)
Accrued expenses and other current liabilities (including $20 and $36 for a related party)			419	(550)
Operating lease liabilities			17
Net cash used in operating activities			(31,313)	(12,819)
Cash flows from investing activities:
Purchase of short-term investments			(34,523)
Purchase of property and equipment			(183)
Net cash used in investing activities			(34,706)
Cash flows from financing activities:
Proceeds from the issuance of redeemable convertible preferred stock, net of issuance costs				1,591
Proceeds from the issuance of convertible promissory notes (including $3,402 and $9,993 from a related party), net of issuance costs			7,500	9,993
Cash acquired in connection with the Merger			102,113
Payment of deferred transaction costs and issuance costs			(2,346)	(22)
Proceeds from the exercise of stock options				1
Net cash provided by financing activities			107,267	11,563
Net increase (decrease) in cash and cash equivalents and restricted cash			41,248	(1,256)
Cash and cash equivalents and restricted cash, at beginning of the period			1,639	3,169
Cash and cash equivalents and restricted cash, at end of the period	42,887	1,913	42,887	1,913
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	42,387	1,913	42,387	1,913
Restricted cash	500		500
Total cash, cash equivalents and restricted cash, at end of the period	$ 42,887	$ 1,913	42,887	$ 1,913
Supplemental disclosure of cash flow information:
Right-of-use assets obtained in exchange for operating lease liability			1,528
Purchases of property and equipment included in accounts payable and accrued expenses and other current liabilities			16
Merger transaction costs recognized in additional paid-in capital			5,357
Recognition of AlloVir common stock outstanding at the closing of the Merger			104,990
Issuance of redeemable convertible preferred stock upon conversion of convertible promissory notes			3,695
Conversion of redeemable convertible preferred stock into common stock in connection with the Merger			49,694
Conversion of convertible promissory notes and accrued interest in connection with the Merger			$ 20,799