Treovir Launches Phase 2 Trial for G207 in Children with Recurrent Brain Tumors

BIRMINGHAM, AL, USA I December 4, 2024 I Treovir, Inc. has announced the commencement of a Phase 2 clinical trial to test G207, an oncolytic HSV immunotherapy, for pediatric brain tumor patients. The trial will focus on the treatment's effectiveness in managing high-grade gliomas at their first recurrence, a type of fatal pediatric brain tumor for which no therapies are currently approved. The study, which will be conducted in a single-arm format, includes 30 pediatric patients.

The main aim of the Phase 2 trial is to measure overall survival and to confirm the safety of G207, a genetically engineered virus designed to target and destroy malignant brain tumor cells. The trial is being conducted in collaboration with the Pediatric Brain Tumor Consortium, supported by the National Cancer Institute (NCI), which is a part of the National Institutes of Health. It is currently open for patient enrollment at Memorial Sloan Kettering Cancer Center and The University of Texas MD Anderson Cancer Center. Treovir expects to open additional sites in the US and Canada in late 2024 and 2025.

Michael Christini, CEO of Treovir, expressed optimism about the trial, noting that the company aims to expand on the promising results obtained from the Phase 1 study completed in 2021. He emphasized the critical need for approved therapies for pediatric gliomas and anticipates that the data from the Phase 2 study will support a Biologics License Application (BLA) for G207, potentially providing a new treatment option for this underserved patient population.

Treovir, Inc. is a clinical-stage biopharmaceutical company dedicated to developing and commercializing oncolytic Herpes Simplex Viruses (oHSV) to treat malignant brain tumors in children. These oHSV are genetically modified to infect and kill cancerous brain tumor cells, subsequently triggering a strong immune response. The FDA has granted Fast-Track status to G207, and the treatment also holds orphan drug designations for various types of pediatric brain tumors in both the US and the EMA.

Brain tumors represent the most common solid tumors in children, with particularly aggressive forms like glioblastoma having a very low survival rate—around 10 percent at five years post-diagnosis. Malignant high-grade gliomas constitute 8 to 10 percent of pediatric brain tumors, with survival rates stagnant for the past three decades. For recurrent high-grade gliomas, the median life expectancy is only 5.6 months.

The Phase 1 dose-escalation study, published in the New England Journal of Medicine in 2021, involved 12 pediatric patients aged 7 to 18 years with progressive high-grade glioma. These patients received a single intratumoral infusion of G207, either alone or combined with radiation. The study reported no dose-limiting toxic effects or serious adverse events attributed to G207. Radiographic, neuropathological, or clinical responses were observed in 11 patients, with a median overall survival of 12.2 months—more than double the typical survival rate for such conditions. Five of the 12 patients survived beyond 18 months, exceeding the expected survival rate for newly diagnosed cases. Furthermore, G207 significantly increased the number of tumor-infiltrating lymphocytes for at least nine months post-infusion, activating the patient's immune system to combat the tumor.

Aside from the Phase 2 trial, G207 is also being assessed for safety in a Phase 1 clinical trial for children with recurrent or progressive malignant cerebellar gliomas or medulloblastomas. This trial, conducted at MD Anderson Cancer Center, is partially supported by an FDA grant awarded to Dr. Gregory K. Friedman, the principal investigator for both trials. Treovir is also planning a Phase 1/2 clinical study for newly diagnosed brain tumor patients, expected to begin in 2026.