Study of a Retroviral Replicating Vector Combined With a Prodrug to Treat Patients Undergoing Surgery for a Recurrent Malignant Brain Tumor

Inclusion Criteria (must all be answered "Yes"): * Has the patient given written informed consent? * Is the patient between 18 years old and 80 years old inclusive? * Has the patient had histologically proven HGG with recurrence or progression following initial definitive therapy(s) such as surgery with or without adjuvant radiation therapy and/or chemotherapy (confirmed by diagnostic biopsy or contrast-enhanced MRI and evaluable by Macdonald criteria)? Note if first recurrence of GBM is documented by MRI, an interval of at least 12 weeks after the end of prior radiation therapy is required unless there is either: i) histopathologic confirmation of recurrent tumor, or ii) new enhancement on MRI outside of the radiotherapy treatment field. * Does the patient have a single, HGG tumor recurrence/progression that is ≤ 5 cm in its greatest dimension? * Based on the pre-operative evaluation, is the tumor recurrence/progression a candidate for ≥ 80% resection? * Has the patient elected not to undergo treatment with the Gliadel® wafer? * Does the patient have a Karnofsky performance status ≥ 70? * Does the patient have an absolute neutrophil count (ANC) ≥ 1500/mm3? * Does the patient have an absolute lymphocyte count ≥ 500/mm3? * Does the patient have a platelet count ≥ 100,000/mm3? * Does the patient have a Hgb ≥ 10 g/dL? * Does the patient have a normal PT/PTT? (subnormal PT/PTT acceptable) * Does the patient have an estimated glomerular filtration rate of at least 50 mL/min (incl…