Researchers here have discovered how a specific chemotherapy drug helps a cancer-killing virus. The virus is being tested in animals for the treatment of incurable human brain tumors. The virus, a modified herpes simplex virus, is injected directly into the tumor, where it enters only the cancer cells and kills them.
The study found, however, that within hours of the injection, infection-fighting immune cells are drawn into the tumor to attack the virus, reducing the treatment's effectiveness.
They also found that a chemotherapeutic drug called cyclophosphamide briefly weakens those immune cells, giving the anti-cancer virus an opportunity to spread more completely through the tumor and kill more cancer cells.
Specifically, the drug slows the activity of immune cells called natural killer (NK) cells and macrophages, which are the body's first line of defense against infections.
The virus and drug cannot be used yet in humans because they require further study, as well as testing for safety and effectiveness through the clinical trials process.
The research, led by investigators with the Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, is published in the Aug. 22 issue of the Proceedings of the National Academy of Sciences.
