O6-benzylguanine (BG) and temozolomide (TMZ) therapy of glioblastoma multiforme (GBM) with infusion of autologous lentiviral transduced P140KMGMT+ hematopoietic progenitors to protect hematopoiesis: A phase I study.

TPS1616 Background: The administration of radiation therapy (RT) and concomitant and adjuvant temozolomide (TMZ) for the treatment of newly-diagnosed glioblastoma (GBM) is associated with modestly prolonged survival. However, the benefit of concurrent therapy is restricted to a subgroup of patients whose tumor exhibits methylation of the promoter for methylguanine-DNA-methyltransferase (MGMT). Promoter methylation silences the expression of DNA alkyltransferase (AGT), the product of the MGMT gene which functions to repair alkylated DNA. Unfortunately, the majority of GBMs have non-methylated MGMT promoters and do not appear to benefit from adding TMZ to radiotherapy. Two potential strategies for targeting MGMT-induced chemoprotection in gliomas include depletion of tumor MGMT, and dose escalation of TMZ accomplished by minimizing TMZ-induced bone marrow toxicity. In this study, we propose to combine the irreversible MGMT inhibitor O6-benzylguanine (BG) with infusion of autologous hematopoetic stem cells (...