Astellas and Vir Biotechnology announced a global co‑development and commercialization agreement centered on VIR‑5500, Vir’s PRO‑XTEN dual‑masked CD3 T‑cell engager targeting PSMA in prostate cancer. Under the deal Vir will receive upfront cash, equity and near‑term milestone payments totaling in the low hundreds of millions, with potential future milestones and royalties that could reach well over a billion dollars. Astellas will leverage its development and regulatory infrastructure to advance the program globally while Vir retains upside through milestones and royalties. The transaction underscores big‑pharma appetite for masked T‑cell engagers and for partnering with oncology‑pivoting biotech firms to accelerate clinical development. Deal terms provide Vir with near‑term capital and de‑risking while giving Astellas a shot at a next‑generation prostate cancer immunotherapy should the candidate clear clinical hurdles.