ImmVira, a global biotechnology company, presented encouraging Phase I clinical data for its oncolytic herpes simplex virus (oHSV) therapy MVR-C5252 at the 2025 American Association for Cancer Research (AACR) annual meeting. The study, conducted in collaboration with Duke University, demonstrated a favorable safety profile in patients with recurrent high-grade glioma, a devastating brain cancer with a five-year survival rate of less than 5%.
Novel Delivery Approach Shows Promise
The Phase I trial utilized convection-enhanced delivery (CED) to administer MVR-C5252 directly into the brain, bypassing the blood-brain barrier that typically limits drug penetration into central nervous system tumors. Unlike conventional Ommaya reservoir systems, CED provides sustained positive pressure through an implanted catheter, ensuring even drug distribution throughout the target brain region and enabling multiple dosing cycles.
To date, five patients with recurrent high-grade glioma have received MVR-C5252 treatment through this innovative delivery method. In Stage 1A of the study, three patients received a dose of 5×10⁶ plaque-forming units (PFU) and successfully completed the dose-limiting toxicity evaluation period.
Encouraging Safety and Bioactivity Data
The trial results revealed no serious adverse events, dose-limiting toxicities, or Grade 3-5 adverse events among treated patients. The only reported side effects were mild Grade 1-2 adverse events, including fatigue, flu-like symptoms, and cognitive disturbance, indicating a manageable safety profile for this direct brain delivery approach.
Serial cytokine analysis of cerebrospinal fluid demonstrated dynamic immune responses and intended biological activity, with measurable changes in cytokine concentrations following treatment infusion. These biomarker changes suggest that MVR-C5252 is successfully engaging the immune system as designed.
Engineered for Dual Mechanism of Action
Developed on ImmVira's proprietary OVPENS platform, MVR-C5252 represents an advanced approach to oncolytic virotherapy. The therapy is specifically engineered with designed attenuation to achieve targeted killing of malignant glioma cells while being armed with PD-1 antibody and interleukin-12 (IL-12) to create synergistic anti-tumor effects through combined "oncolysis plus immune activation."
This dual mechanism approach addresses the immunosuppressive tumor microenvironment characteristic of glioblastoma while directly destroying cancer cells through viral replication. The incorporation of checkpoint inhibition and immune stimulation components aims to generate a more robust and durable anti-tumor response.
Regulatory Recognition and Strategic Focus
MVR-C5252 has received Investigational New Drug approval in both the United States and China, reflecting the therapy's potential across major pharmaceutical markets. The U.S. Food and Drug Administration has also granted Orphan Drug Designation to the product, recognizing the significant unmet medical need in malignant glioma treatment.
"We are committed to developing advanced therapies featuring novel modalities using oHSV and engineered exosomes, to address complex and challenging diseases," said Dr. Grace Guoying Zhou, ImmVira's Chairwoman and CEO. "After years of parallel development and in-depth explorations in both the U.S. and China, we have strategically focused on malignant glioma for the development of MVR-C5252, leveraging HSV-1's unique biological and translational medical characteristics."
Collaboration with Leading Institution
The partnership with Duke University, a globally recognized leader in glioma research and treatment, provides significant expertise in oncolytic virotherapy, immunotherapy, and central nervous system treatments. This collaboration is expected to accelerate the clinical development of MVR-C5252 and enhance the scientific rigor of ongoing studies.
The current results represent an important milestone for oncolytic virus therapy in brain cancers, where traditional treatments have shown limited efficacy. As the study continues to enroll patients and advance through dose escalation phases, the data will provide crucial insights into the therapeutic potential of this innovative approach for one of oncology's most challenging malignancies.
