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Astellas Pharma Inc. and Vir Biotechnology, Inc. are teaming up globally to develop and commercialize VIR-5500, a PSMA-targeting PRO-XTEN dual-masked CD3 T-cell engager for prostate cancer. Not a small move. This research focuses on metastatic castration-resistant prostate cancer which presents challenges in survival rates and provides limited treatment choices after patients develop resistance to current therapies.
The current status of VIR-5500 involves its Phase 1 trial for patients with advanced metastatic prostate cancer. The science angle matters here. It binds to PSMA and CD3, but uses PRO-XTEN masking technology so the T-cell engager stays inactive until it reaches the tumor microenvironment. The idea is simple. Hit the tumor. Limit off-target damage. Improve the therapeutic window.
Now the structure of the deal. Vir gets 335 million dollars in upfront and near-term payments. The total amount includes 240 million cash, 75 million which will be converted into equity at a 50 percent premium, and a 20 million payments which will be made to achieve short-term goals. Vir has the potential to receive 1.37 billion dollars through all development and regulatory and sales achievement milestones. On ex-U.S. net sales, they are eligible for tiered double-digit royalties.
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Development costs will be split. Astellas takes 60 percent. Vir takes 40 percent. Vir keeps running the ongoing Phase 1 study for now. After transition, Astellas takes over development activities. In the U.S., profits and losses are split 50 50, and Vir has the option to co-promote. Outside the U.S., Astellas gets exclusive commercialization rights.
There is another layer. Under Vir’s prior licensing agreement with Sanofi, part of certain collaboration proceeds will be shared with Sanofi. Lazard advised Vir on the deal. Closing still depends on standard conditions, including clearance under the Hart-Scott-Rodino Act.
Vir is also hosting a conference call alongside its fourth quarter and full year 2025 results, where updated Phase 1 data for VIR-5500 will be discussed, including data being presented at the 2026 ASCO Genitourinary Cancers Symposium.
Big oncology bet. Shared risk. Shared upside. Now it comes down to what the clinical data shows.
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