Subsequent Event

3 Months Ended

Mar. 31, 2026

Subsequent Events [Abstract]

Subsequent Event

Subsequent Event

License Agreement with Astellas US LLC

On April 15, 2026, the Company closed the previously announced Collaboration and License Agreement with Astellas US LLC, together with its subsidiaries and affiliates, including its indirect parent, Astellas Pharma Inc. (the Astellas Agreement). Under the Astellas Agreement the parties entered into a global strategic collaboration to co-develop and co-commercialize VIR-5500, an investigational PRO-XTEN® dual-masked CD3 TCE targeting PSMA (Prostate-Specific Membrane Antigen) for the treatment of prostate cancer that is currently in Phase 1 development, through a sharing of expenses and revenues. Pursuant to the Astellas Agreement, the Company granted Astellas, subject to certain intellectual property rights of Sanofi, an exclusive, worldwide license to develop, manufacture, commercialize and otherwise exploit VIR-5500 and certain related derivative compounds for therapeutic, prophylactic, palliative and diagnostic uses.

Under the terms of the Astellas Agreement, in the U.S., the Company will share profits and losses from future sales of VIR-5500 equally with Astellas, should VIR-5500 receive regulatory approval, and the Company will have the option to co-promote VIR-5500. Outside of the U.S., Astellas will obtain exclusive rights to commercialize VIR-5500 and be responsible for all commercialization costs. The Company and Astellas will jointly develop VIR-5500, with global clinical development costs shared 40% by the Company and 60% by Astellas, while costs of U.S.-specific studies will be shared equally, and Astellas will be solely responsible for costs of ex-U.S.-specific studies. In addition, the Company has the option to opt out of development cost sharing responsibilities and U.S. profit sharing, and in such case, Astellas will pay the Company royalties on net sales made in the U.S., as described below.

The Company received a $75 million equity investment payment pursuant to a separate Stock Purchase Agreement (the Astellas SPA, described further below) at closing, and the Company will receive a $240 million upfront payment within 30 days of closing. A $20 million milestone payment is due upon completion of manufacturing technology transfer, anticipated in the second quarter or third quarter of 2027. The Company will be eligible to receive up to an additional $1.37 billion in future development, regulatory and ex-U.S. sales milestones, along with tiered, double-digit royalties on ex-U.S. net sales. If the Company elects to opt out of development cost sharing responsibilities and U.S. profit sharing, it would be eligible to receive up to $1.37 billion (or $1.60 billion if the Company has met a pre-defined limited funding threshold at the time of the opt-out) in future development, regulatory and global sales milestones, along with tiered, double-digit royalties on global net sales. Further, certain opt-out milestones, if met, will include reimbursement of a portion of the Company’s previously expensed development and commercialization spend.

Under the terms of the Sanofi Agreement, the Company will share with Sanofi 20% of certain future collaboration proceeds, including the upfront payment and the portion of milestones, profit-share and royalties that exceed amounts already owed to Sanofi.

Concurrently with the closing of the Astellas Agreement, the Company also closed the Astellas SPA, pursuant to which Astellas purchased 7,239,382 shares of the Company’s common stock at $10.36 per share for an aggregate purchase price of approximately $75 million. The Astellas SPA includes standstill, voting and lockup provisions, with customary exceptions, that expire one year after the date of the closing of the Astellas SPA. One year after the closing of the Astellas SPA, Astellas will have, under certain circumstances, a customary right to require the Company to register the resale of the shares purchased pursuant to the Astellas SPA.