Phase 1 trial of temozolomide plus irinotecan plus O6-benzylguanine in adults with recurrent malignant glioma

BACKGROUND: The current study was a phase 1 clinical trial conducted with patients who had recurrent or progressive malignant glioma (MG). The trial was designed to determine the maximum tolerated dose (MTD) and toxicity of irinotecan (CPT-11) when administered with temozolomide (TMZ) and O6-benzylguanine (O6-BG). METHODS: All 3 drugs, CPT-11, TMZ, and O6-BG, were administered on Day 1 of a 21-day treatment. First, patients were treated with a 1-hour bolus infusion of O6-BG at a dose of 120 mg/m2 followed immediately by a 48-hour continuous infusion of O6-BG at a dose of 30 mg/m2/d. Second, within 60 minutes of the end of the 1-hour bolus infusion of O6-BG, TMZ was administered orally at a dose of 355 mg/m2. Third, 1 hour after administration of TMZ, CPT-11 was infused over 90 minutes. Patients were accrued to 1 of 2 strata based on CYP3A1- and CYP3A4-inducing antiepileptic drug (EIAED) use; dose escalation was conducted independently within these strata. RESULTS: Fifty-five patients were enrolled. In both strata, the dose-limiting toxicities were hematologic and included grade 4 neutropenia, febrile neutropenia, leukopenia, and/or thrombocytopenia. For Stratum 1 (EIAEDs), when TMZ was administered at a dose of 355 mg/m2, the MTD of CPT-11 was determined to be 120 mg/m2. In contrast, for Stratum 2 (no EIAEDs), when TMZ was administered at a dose of 200 mg/m2, the MTD of CPT-11 was determined to be 80 mg/m2. CONCLUSIONS: The authors believe that the results of the current study provide the foundation for a phase 2 trial of O6-BG in combination with CPT-11 and TMZ in patients with MG. Cancer 2009. © 2009 American Cancer Society.