Astellas and Vir Biotechnology Announce $1.7B Collaboration for VIR-5500 Prostate Cancer Drug, Including $240M Cash Upfront

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Astellas and Vir Biotechnology announced a global strategic collaboration on February 23, 2026, to advance VIR-5500, a PSMA-targeting PRO-XTEN dual-masked T-cell engager for prostate cancer treatment.126

Vir receives $335M upfront and near-term:
$240M cash, $75M equity investment at 50% premium, and $20M milestone; eligible for up to $1.37B in further milestones and tiered double-digit ex-U.S. royalties.2345

Companies share development costs 60-40 (Astellas-Vir); Vir has U.S. co-promotion option with 50/50 profit split; Astellas handles ex-U.S. commercialization.2356

Updated Phase 1 data from VIR-5500 in metastatic castration-resistant prostate cancer (mCRPC) showed promising anti-tumor activity and manageable safety; Phase 3 planned for 2027.24

Deal validates Vir's oncology pivot from Sanofi-licensed PRO-XTEN platform and strengthens Astellas' prostate cancer position amid Xtandi patent losses.25

Sources:

1. https://investors.vir.bio/news/news-details/2026/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/default.aspx

2. https://www.fiercebiotech.com/biotech/astellas-vir-engage-17b-deal-masked-prostate-cancer-bispecific

3. https://www.stocktitan.net/sec-filings/VIR/8-k-vir-biotechnology-inc-reports-material-event-588666878e34.html

4. https://www.biopharmadive.com/news/vir-astellas-masked-t-cell-engager-prostate-cancer-results/812950/

5. https://www.oncologypipeline.com/apexonco/vir-tempts-astellas

6. https://newsroom.astellas.com/2026-02-24-astellas-and-vir-biotechnology-announce-global-strategic-collaboration-to-advance-psma-targeting-pro-xten-r-dual-masked-t-cell-engager-vir-5500-for-the-treatment-of-prostate-cancer