Vir Biotechnology Completes Astellas Deal to Advance Prostate Cancer Immunotherapy

Vir Biotechnology has entered a global strategic collaboration with Astellas Pharma to co-develop and commercialize an experimental immunotherapy for prostate cancer, following regulatory clearance under U.S. antitrust law.

The agreement centers on VIR‑5500, a prostate-specific membrane antigen (PSMA)–targeted T‑cell engager designed to treat advanced prostate cancer. The companies announced the partnership in February and said Thursday that the deal closed after the expiration of the waiting period required by the Hart‑Scott‑Rodino Antitrust Improvements Act.

Under the terms of the transaction, Vir received a $240 million upfront payment and a $75 million equity investment from Astellas at $10.36 per share. The San Francisco–based biotechnology company is also eligible for a near-term milestone payment of $20 million and up to $1.37 billion in additional development, regulatory, and sales milestones, as well as tiered, double-digit royalties on net sales outside the U.S.

Astellas and Vir will share U.S. development costs and profits for VIR‑5500 equally, while Astellas will lead commercialization in the U.S., with Vir retaining an option to co-promote. Outside the U.S., Astellas will hold exclusive commercialization rights.

Strategic Shift Toward Oncology

The collaboration reflects Vir’s ongoing pivot toward oncology after initially building its business around infectious diseases. VIR‑5500 was acquired as part of a 2024 licensing deal with Sanofi covering the PRO‑XTEN masking technology and multiple clinical-stage T‑cell engager programs. Under Vir’s Sanofi agreement, a portion of certain proceeds from the Astellas deal will be shared with Sanofi.

For Astellas, the partnership strengthens its prostate cancer pipeline as several of its established therapies face future patent expirations. The Japanese pharmaceutical company has a long-standing presence in prostate cancer treatment, including its blockbuster androgen receptor inhibitor Xtandi, co-developed with Pfizer.

Financial and Development Outlook

Vir said the transaction materially extends its cash runway while allowing it to retain meaningful participation in the upside potential of VIR‑5500 in the U.S. market. Astellas will assume primary responsibility for late-stage development and global commercialization, leveraging its oncology infrastructure and clinical development experience.

The collaboration is among the larger immuno-oncology deals announced this year and underscores continued pharmaceutical interest in next-generation T‑cell therapies for solid tumors, an area that has historically proven more challenging than blood cancers.