Astellas Pharma Inc. and Vir Biotechnology, Inc. have entered into a global strategic collaboration to advance VIR-5500, an investigational PRO-XTEN dual-masked CD3 T-cell engager targeting PSMA for the treatment of prostate cancer.

The companies say the collaboration is intended to accelerate development of VIR-5500 while strengthening Astellas’ oncology pipeline and prostate cancer leadership.¹

“Astellas is proud to have helped 1.5 million patients with prostate cancer, and we are dedicated to expanding our impact as part of our R&D strategy. Our deep expertise in this disease area, combined with a growing immuno-oncology (IO) pipeline of biologics, including T-cell engagers, uniquely positions us to help advance VIR-5500, a potentially best-in-class T-cell engager for prostate cancer. This strategic collaboration allows Astellas and Vir Biotechnology to combine our expertise and reaffirms our commitment to improving the lives of people with prostate cancer,” said Adam Pearson, chief strategy officer, Astellas.

Despite recent advances, metastatic castration-resistant prostate cancer (mCRPC) remains difficult to treat, with a five-year survival rate of approximately 30%.¹ Patients who progress to mCRPC often develop therapeutic resistance and face limited treatment options.

VIR-5500 is currently in Phase I development for people with advanced, metastatic prostate cancer (NCT05997615), with the first reported patient being treated back in October 2025.²

The investigational therapy combines a bispecific PSMA and CD3 binding T-cell engager with PRO-XTEN masking technology designed to keep the molecule inactive until it reaches the tumor microenvironment, with the goal of reducing off-target effects and improving the therapeutic index.¹

What are the financial terms and commercialization structure?

Under the terms of the agreement, Vir Biotechnology is set to receive $335 million in upfront and near-term payments, including $240 million in cash, a $75 million equity investment at a 50% premium, and a near-term $20 million milestone.¹

Development costs will be shared globally, with Astellas responsible for 60% and Vir Biotechnology responsible for 40%.

Vir Biotechnology is also expected to continue the ongoing Phase I trial until responsibility transitions to Astellas, after which Astellas will oversee all development activities. In the United States, Vir Biotechnology will have the option to co-promote VIR-5500 with Astellas, with profit and loss shared equally.¹

Outside the United States, Astellas will have exclusive commercialization rights.

Vir Biotechnology is also eligible to receive up to $1.37 billion in development, regulatory, and sales milestones, as well as tiered, double-digit royalties on ex-U.S. net sales. Under Vir Biotechnology’s licensing agreement with Sanofi, a portion of certain collaboration proceeds will be shared with Sanofi.³

Marianne De Backer, M.Sc., Ph.D., MBA, chief executive officer, Vir Biotechnology, added, “Astellas is an ideal collaborator for the VIR-5500 program given the company's successful track record advancing therapies across the treatment continuum, building blockbuster franchises and delivering value to patients through strategic development alliances with other biotech partners. This collaboration will enable more rapid advancement of VIR-5500 to potentially benefit more people living with prostate cancer. We believe this collaboration reflects confidence in our PRO-XTEN platform, which has broad potential across multiple solid tumor indications.”

Sources

1. Astellas and Vir Biotechnology Announce Global Strategic Collaboration to Advance PSMA-targeting PRO-XTEN Dual-masked T-Cell Engager VIR-5500 for the Treatment of Prostate Cancer Astellas Pharma Inc. February 23, 2026 https://www.prnewswire.com/news-releases/astellas-and-vir-biotechnology-announce-global-strategic-collaboration-to-advance-psma-targeting-pro-xten-dual-masked-t-cell-engager-vir-5500-for-the-treatment-of-prostate-cancer-302694866.html
2. Vir Biotechnology Announces First Patient Dosed in Part 3 of Phase 1 Trial of PSMA-Targeting PRO-XTEN® Dual-Masked T-Cell Engager VIR-5500 in Combination with Androgen Receptor Pathway Inhibitors for the Treatment of Metastatic Prostate Cancer Vir Biotechnology October 9, 2025 https://www.businesswire.com/news/home/20251009548229/en/Vir-Biotechnology-Announces-First-Patient-Dosed-in-Part-3-of-Phase-1-Trial-of-PSMA-Targeting-PRO-XTEN-Dual-Masked-T-Cell-Engager-VIR-5500-in-Combination-with-Androgen-Receptor-Pathway-Inhibitors-for-the-Treatment-of-Metastatic-Prostate-Cancer
3. Vir Biotechnology Acts on Expanded Strategy of Powering the Immune System Through Exclusive Worldwide License Agreement with Sanofi for Multiple Potential Best-in-Class Clinical-Stage T-cell Engagers Vir Biotechnology August 1, 2024 https://www.businesswire.com/news/home/20240801918359/en/Vir-Biotechnology-Acts-on-Expanded-Strategy-of-Powering-the-Immune-System-Through-Exclusive-Worldwide-License-Agreement-with-Sanofi-for-Multiple-Potential-Best-in-Class-Clinical-Stage-T-cell-Engagers