Mutant MGMT Gene Transfer Into Human Hematopoietic Progenitors to Protect Hematopoiesis During O6-Benzylguanine (BG, NSC 637037) and Carmustine Followed by Temozolomide Therapy of Advanced Solid Tumors

OBJECTIVES:

• Evaluate the feasibility of introducing and expressing mutant MGMT-G156A cDNA in hematopoietic progenitors taken from patients with advanced solid tumors (including gliomas) or non-Hodgkin's lymphoma using a safety modified retroviral vector MFG.
• Determine the toxicity associated with reinfusion of ex vivo-transduced hematopoietic stem cells into these patients, including the detection of replication competent retrovirus.
• Evaluate the feasibility of identifying mutant MGMT-G156A-transduced and O6-benzylguanine (BG)- and temzolomide-resistant hematopoietic and stromal progenitors from the bone marrow of these patients.
• Evaluate the feasibility of in vivo enrichment of the transduced hematopoietic progenitors in patients treated with BG and temzolomide.
• Evaluate the toxicity of this regimen in these patients.
• Determine the antitumor effect of this regimen in these patients.

OUTLINE: This is a dose-escalation study of CD34 stem cells and carmustine.

After a negative bone marrow sampling, patients receive sargramostim (GM-CSF) and filgrastim (G-CSF) subcutaneously (SC) once daily on days 1-5 (or G-CSF twice daily alone for 4-5 days). Peripheral blood progenitor cells are collected 24 hours after the last dose of growth factor injection on day 5 and also on day 6, if necessary. The CD34 positive stem cells are then infected by the retroviral mutant MGMT-G156A ex vivo.

Patients receive O6-benzylguanine (BG) IV over 1 hour followed by carmustine IV over 1 hour every 6 weeks for 5 courses, assuming recovery of peripheral blood counts. Approximately 72 hours after the end of the first course of chemotherapy, patients receive reinfusion of retrovirally-transduced hematopoietic stem cells over 5-10 minutes. Four weeks after the completion of BG and carmustine, patients receive BG IV over 1 hour followed by temozolomide IV over 1 hour every 4 weeks for up to 5 courses, in the absence of hematologic toxicity. Patients with responding disease may continue to receive BG and temzolomide in the absence of disease progression or unacceptable toxicity provided other phase II studies indicate the safety of more than 5 courses.