Astellas and Vir Biotechnology Forge Global Collaboration to Advance Prostate Cancer T-Cell Engager VIR-5500

Astellas Pharma and Vir Biotechnology announced a global strategic collaboration to co-develop and co-commercialize VIR-5500, a PRO-XTEN® dual-masked T-cell engager targeting prostate-specific membrane antigen (PSMA) for the treatment of advanced prostate cancer. Under the agreement, Astellas will lead commercialization in the U.S. and hold exclusive rights outside the U.S., while Vir will receive $335 million in upfront and near-term payments and is eligible for up to $1.37 billion in additional milestones.

Accelerating Prostate Cancer Innovation

VIR-5500 combines PSMA and CD3 targeting with dual-masking technology designed to remain inactive until it reaches the tumor microenvironment, potentially improving safety and efficacy in metastatic castration-resistant prostate cancer (mCRPC). The collaboration leverages Astellas’ global oncology footprint and Vir’s PRO-XTEN® platform to potentially bring a best-in-class T-cell engager to a high-unmet-need cancer indication.

Strategic and Commercial Implications

The deal’s structure shares development costs (60/40 in favor of Astellas) and U.S. profits and losses equally, with Vir retaining co-promotion rights in the U.S. and earning tiered, double-digit royalties ex-U.S. Beyond financial validation, the partnership underscores a broader industry shift toward immuno-oncology and advanced T-cell engagers designed for solid tumors, where toxicity and delivery challenges have historically limited progress.