Vir Biotechnology, Inc. (VIR) reported positive Phase 1 results for VIR-5500 in patients with advanced metastatic castration-resistant prostate cancer who had progressed after multiple prior treatments, showing the investigational therapy was generally well tolerated and demonstrated encouraging anti-tumor activity. The company's shares rose more than 50% in after-hours trading.
Across all patients receiving VIR-5500 monotherapy in the Phase 1 study, the treatment was generally well tolerated with no dose-limiting toxicities observed to date.
Dose-dependent activity was observed across the treatment group, measured by prostate-specific antigen (PSA) declines and radiographic responses. In the highest dose cohorts, as of the January 9, 2026 data cut-off, PSA50 declines were seen in 82% of PSA-evaluable patients, while PSA90 declines occurred in 53% .
Among RECIST (Response Evaluation Criteria in Solid Tumors)- evaluable patients, objective responses were seen in 45% , including four confirmed responses and one pending confirmation. Reductions on PSMA-PET scans supported PSA and radiographic findings, with tumor shrinkage observed across multiple lesions, including visceral metastases.
"We are encouraged by VIR-5500's safety and tolerability profile and the early signals of durable anti-tumor activity in a heavily pre-treated population, which validate our PRO-XTEN masking strategy aimed at achieving a differentiated therapeutic index," said Marianne De Backer, Chief Executive Officer, Vir Biotechnology. "Based on these data, we are advancing dose-expansion cohorts and plan to initiate our registrational trial in 2027.
Monday, Vir Biotechnology stock closed at $7.43, down 1.72%.
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May 15, 2026 15:25 ET Apart from the confirmation of Kevin Warsh as the next Fed chair, the main news on the economics front this week included key price data from the U.S. and the first quarter economic growth figures from major economies. Both consumer prices and producer costs have started to reflect the effect of supply shocks due to the Middle East conflict. In Europe, GDP data was in focus, while inflation data from China dominated the news flow in Asia.