The management of patients with glioblastoma remains challenging with an average survival of 32-56 weeks. We report on a clinical trial of patients with recurrent glioblastoma treated with adenovirus/herpex simplex-thymidine kinase/ganciclovir (ADV/HSV-tk/GC). Entry criteria for this study included: recurrent malignant glioma after surgical resection and conventional radiation therapy. At the time of recurrence, computerized volumetric resection of the tumor was performed and the ADV/HSV-tk complex was injected in the tumor bed. GC was administered 24 h after surgery (10 mg/kg/day) for 7 days. Patients were divided into 3 ADV/HSV-tk dose-escalating cohorts. Adenoviral vector shedding, and local or systemic toxicity did not occur in this study. Magnetic resonance imaging showed lack of increased brain edema in the treated patients. Histological examination of the 5 patients that had repeated surgery after gene therapy treatment showed lack of tissue toxicity. Additionally, PCR for HSV-tk was negative in the brain 3 months after injection. The patients' Karnofsky score was maintained > or = 70 in 8/10 patients (80%) and 5/9 patients (55%) 3 and 6 months respectively, after gene therapy. Ten of 11 patients survived > or = 52 weeks from diagnosis with an average survival of 112.3 weeks. One patient is still alive 248 weeks from diagnosis. These data show that the ADV/HSV-tk/GC complex at the dose used in this study is safe. Additional dose escalation is currently in progress.