Adenovirus Mediated Suicide Gene Therapy With Radiotherapy in Progressive Astrocytoma.

Detailed study description: Patients with recurrent glioblastoma (GBM) or progressive high grade astrocytoma who are scheduled to undergo repeat surgery are eligible. After the removal of as much tumor tissue as possible, a modified oncolytic adenovirus is injected into the wall of the resection cavity and any residual tumor tissue. The goal of this study is to determine the maximum tolerated dose (MTD) of the injected adenovirus. This treatment is combined with a combination of oral 5-fluorocytosine (5-FC) and valganciclovir (vGCV) prodrug therapy. Following the surgery, patients will be treated with fractionated radiosurgery (fSRS). Patients will be monitored for 30 days before they start on next line anti-cancer therapy.