Cure rates for patients with high grade glioma remain disappointing, in part because tumor cells are often resistant to chemotherapy, and because using higher doses of chemotherapy causes damage to normal blood cells. This trial is designed to try to overcome both of these barriers. The idea is to make tumor cells more sensitive to a chemotherapy agent, Temozolomide, by using 06Benzylguanine (06BG). In addition, patients will have a portion of their blood cells modified by the insertion of a chemotherapy resistance gene which may help protect blood cells from damage by the combination of the Temozolomide and 06BG.