 The purpose of this study was to evaluate the safety and potential efficacy of Gene Mediated Cytotoxic Immunotherapy for malignant gliomas. The approach used an adenoviral vector disabled virus engineered to express the Herpes thymidine kinase gene aglatimagene besadenovec, AdV-tk, followed by an antiherpetic prodrug, valacyclovir. The AdV-tk vector was injected into the resection bed after standard tumor surgery and valacyclovir pills were taken for 14 days. Standard radiation and chemotherapy were administered which have been shown to work cooperatively with AdV-tk prodrug to kill tumor cells. The hypothesis is that this combination therapy can be safely delivered and will lead to improvement in the clinical outcome for patients with newly diagnosed malignant gliomas, including glioblastoma multiforme WHO grade IV and anaplastic astrocytomas WHO grade III. 