The use of temozolomide (TEM) both during and after irradiation is a promising new approach for the treatment of patients with high-grade glioma. However, this treatment is limited by tumor cell resistance and therapy-related hematologic toxicity. To overcome TEM resistance, in this study we will add the chemotherapy sensitizing drug O6-Benzylguanine (BG). To overcome hematologic toxicity, patients will receive autologous hematopoietic stem cells transduced with a chemotherapy resistance gene designed to protect these cells from subsequent therapy with this drug combination.