The potential benefit of using transduced blood stem cells is the possibility for dose escalation of TEM, since hematologic toxicity has heretofore limited higher doses. Transduction will be accomplished with a retroviral vector carrying MGMTP140K, which codes for a mutated form of the resistance protein methylguanine-DNA methyltransferase (MGMT). Successful transduction of hematopoietic cells with MGMTP140K makes them resistant to the toxic effects of both TEM + BG. Repeated doses of these drugs should therefore result in an increase in the percentage of transduced (and thus protected) blood stem cells, thus reducing the likelihood of hematologic toxicity with further therapy. Accordingly, patients who are tolerating therapy well and who have laboratory evidence of chemoprotection will receive intrapatient dose escalation of TEM + BG during courses 2-6.