Astellas and Vir partner on VIR-5500, a masked PSMA T-cell engager for prostate cancer. $335M deal accelerates Phase 1 trials for mCRPC. Learn terms, quotes, and impact.
Written By: Pharmacally Medical News Desk
Astellas Pharma Inc. and Vir Biotechnology, Inc. have formed a global strategic collaboration to fast-track VIR-5500, an investigational PRO-XTEN® dual-masked CD3 T-cell engager (TCE) targeting prostate-specific membrane antigen (PSMA). This partnership aims to accelerate development for advanced prostate cancer, bolstering Astellas’ oncology pipeline and leadership in the field.
Prostate cancer, particularly metastatic castration-resistant prostate cancer (mCRPC), poses major challenges. Despite treatment advances, mCRPC carries a grim 5-year survival rate of about 30%, with patients often developing resistance and facing limited options.
VIR-5500 addresses this gap as a potential best-in-class PSMA-targeting TCE. Currently in Phase 1 trials (NCT05997615) for advanced metastatic prostate cancer, it pairs a bispecific PSMA-CD3 binder with PRO-XTEN® masking technology.
This keeps the TCE inactive until it reaches the tumor microenvironment, minimizing off-target effects and enhancing safety.
Adam Pearson Astellas, Chief Strategy Officer highlights Astellas’ impact on 1.5 million prostate cancer patients, deep expertise, and immuno-oncology pipeline (including T-cell engagers). Positions the partnership as a way to advance potentially best-in-class VIR-5500 by combining strengths and reaffirming commitment to patient lives.
Marianne De Backer, Vir’s Chief Executive Officer praises Astellas’ track record in therapies, franchises, and alliances. Notes the deal accelerates VIR-5500 for prostate cancer patients and validates PRO-XTEN® platform’s potential across solid tumors.
Financial and Operational Terms
Vir receives $335 million upfront and near-term, including $240 million cash, $75 million equity at a 50% premium, and a $20 million milestone. Development costs split 60/40 (Astellas/Vir), with Vir finishing Phase 1 before handing over to Astellas.
In the U.S., Vir opts for co-promotion with equal profit/loss sharing; outside-U.S., Astellas handles commercialization exclusively. Vir stands to gain up to $1.37 billion in milestones plus tiered double-digit royalties on ex-U.S. sales. Some proceeds go to Sanofi per Vir’s prior licensing deal.
This alliance leverages Astellas’ immuno-oncology strengths and Vir’s innovative platform, which shows promise across solid tumors. It signals strong momentum for TCEs in prostate cancer, potentially transforming outcomes for mCRPC patients.
Reference
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, 23 February 2026, Astellas and Vir Biotechnology Announce Global Strategic Collaboration to Advance PSMA-targeting PRO-XTEN<sup>®</sup> Dual-masked T-Cell Engager VIR-5500 for the Treatment of Prostate Cancer
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, 23 February 2026, Vir Biotechnology, Inc. – 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
Vir Biotechnology Reports Positive Updated Phase 1 Results for PSMA-targeting, PRO-XTEN® Dual-masked T-Cell Engager VIR-5500 in Patients with Metastatic Prostate Cancer, 23 February 2026,Vir Biotechnology, Inc. – Vir Biotechnology Reports Positive Updated Phase 1 Results for PSMA-targeting, PRO-XTEN® Dual-masked T-Cell Engager VIR-5500 in Patients with Metastatic Prostate Cancer
Safety, Pharmacokinetics, and Preliminary Efficacy of VIR-5500 (AMX-500) in Prostate Cancer, ClinicalTrials.gov ID NCT05997615, Study Details | NCT05997615 | Safety, Pharmacokinetics, and Preliminary Efficacy of VIR-5500 (AMX-500) in Prostate Cancer | ClinicalTrials.gov