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Vir Biotechnology Announces First Patient Dosed in Phase 1 Dose-expansion Cohorts Evaluating PSMA-targeted, PRO-XTEN® Dual-masked T-cell Engager VIR-5500 in Patients with Metastatic Prostate Cancer
Phase 1 trial designed to assess the safety, pharmacokinetics and preliminary efficacy of VIR-5500 in both early and late-line metastatic
About this update from Vir Biotechnology, Inc.
[{"type":"text","content":"\n\nPhase 1 trial designed to assess the safety, pharmacokinetics and preliminary efficacy of VIR-5500 in both early and late-line metastatic castration-resistant prostate cancer (mCRPC) and metastatic hormone-sensitive prostate cancer (mHSPC)\n\n\n\nDose-expansion builds on promising Phase 1 monotherapy dose-escalation data in mCRPC presented in February 2026\n\n\n\n SAN FRANCISCO--(BUSINESS WIRE)--\nVir Biotechnology, Inc. (Nasdaq: VIR) today announced that the first patient has been dosed in one of three expansion cohorts in the Phase 1 trial evaluating VIR-5500, a prostate-specific membrane antigen (PSMA)-targeted, PRO-XTEN® dual-masked T-cell engager (TCE) for metastatic prostate cancer (NCT05997615). The Phase 1 trial is measuring the safety and efficacy of VIR-5500 monotherapy in late-line mCRPC, and of VIR-5500 in combination with an androgen receptor pathway inhibitor (ARPI) in early-line mCRPC and mHSPC.\n\n\n“The initiation of the VIR-5500 expansion cohorts underscores the significant momentum behind this program and the enthusiasm we are seeing across the clinical community,” said Marianne De Backer, M.Sc., Ph.D., MBA, Chief Executive Officer, Vir Biotechnology. “We are encouraged by the promising anti-tumor activity shown in the Phase 1 data announced earlier this year and look forward to collaborating with Astellas after closing of the transaction to explore VIR-5500’s potential to make a meaningful difference across the spectrum of metastatic prostate cancer.”\n\n\nThe monotherapy expansion cohort in late-line mCRPC is the first to begin enrollment based on the monotherapy dose-escalation data that showed VIR‑5500 has a favorable safety profile and promising anti-tumor activity in mCRPC. These safety and efficacy data were presented at the 2026 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium in February. Based on these data, the selected dose regimen to be evaluated in this monotherapy expansion cohort is Q3W 800/2000/3500 µg/kg step-up dosing. This expansion cohort will measure safety and efficacy, including Prostate-Specific Antigen (PSA) response rate and Objective Response Rate (ORR) in patients with mCRPC who are refractory following treatment with multiple prior lines of therapy including at least one second-generation ARPI and one taxane regimen in addition to standard-of-care r...