VIR-5500 receives FDA Fast Track designation for advanced prostate cancer
Published in Drugs development & discovery, Immunology.
October 8, 2026 — Vir Biotechnology announced FDA Fast Track designation for VIR-5500 in late-line metastatic castration-resistant prostate cancer. The candidate is being developed with Astellas.
VIR-5500 links PSMA on cancer cells with CD3 on T cells. Its PRO-XTEN masking technology is designed to keep the molecule inactive until proteases in the tumor microenvironment remove the masks. Restricting activation in this way aims to reduce toxicity, but that goal requires clinical confirmation.
The candidate is being evaluated in an open-label, non-randomized phase 1 study, NCT05997615. Six expansion cohorts examine monotherapy and combinations with established prostate cancer drugs. The companies anticipate starting phase 3 trials in 2027.
Fast Track is intended to facilitate development and regulatory review for serious conditions with unmet needs. It is not marketing approval or proof of clinical benefit. The announcement refers to previously reported phase 1 observations; it does not provide new randomized evidence of improved survival.
Source: Vir Biotechnology company announcement dated October 8, 2026.