Researchers have shown that a genetically modified virus can help the immune system attack glioblastoma, one of the most aggressive brain cancers. The study was published in Cell.
Glioblastoma is usually resistant to immunotherapy because it is considered an “immune cold” tumor, meaning immune cells do not easily enter or attack it. In this study, scientists used a modified herpes simplex virus designed to infect only cancer cells.
The virus works in three main ways. First, it selectively infects and multiplies inside glioblastoma cells without harming healthy brain tissue. Second, it kills the cancer cells and releases new virus particles that spread to nearby tumor cells. Third, this infection triggers an immune response, sending alarm signals that attract T cells into the tumor.
In a Phase 1 clinical trial involving 41 patients with recurrent glioblastoma, the treatment showed promising results. Patients lived longer than expected compared to historical averages, especially those who already had antibodies against the virus. The therapy led to long-term presence of cancer-fighting T cells inside the tumors. Patients had the best outcomes when T cells were found close to dying tumor cells. The treatment also expanded existing anti-tumor T cells in the brain, not just newly recruited ones.
For decades, treatment options for glioblastoma have changed very little. This study shows that it is possible to draw immune cells deep into brain tumors, potentially making them more responsive to immunotherapy. The findings suggest that combining oncolytic viruses with other immune-based treatments could further improve survival in the future.