Ionizing radiation improves survival in mice bearing intracranial high-grade gliomas injected with genetically modified herpes simplex virus

Malignant gliomas remain incurable with current interventions. Encouraging investigational approaches include the use of genetically modified herpes s implex-1 (HSV-1) viruses as direct cytotoxic agents. Combining attenuated H SV-1 with standard therapy, human U-87 malignant glioma xenografts grown in the hind limb or intracranially in athymic nude mice were exposed to ioniz ing radiation, inoculated with genetically modified HSV R3616, or received both virus and radiation. The combination of virus with fractionated ionizi ng radiation suggests a synergistic action and results in reduced tumor vol umes and longer survivals when compared with treatment with either modality alone.