Phase II trial of combined irinotecan and oxaliplatin given every 3 weeks to patients with metastatic colorectal cancer

BACKGROUND: Both irinotecan and oxaliplatin are active agents in the treatment of patients with metastatic colorectal cancer, and there is a strong preclinical rationale for combining these 2 agents. Therefore, a Phase II trial was designed and conducted to determine the efficacy and tolerability of combined irinotecan and oxaliplatin given every 3 weeks to patients with metastatic colorectal cancer. METHODS: Patients with previously untreated metastatic colorectal cancer received irinotecan at a dose of 175 mg/m2 and oxaliplatin at a dose of 130 mg/m2, both given intravenously every 3 weeks. Objective responses were evaluated every 2 courses and were confirmed at least 4 weeks after the initial determination. RESULTS: Fifty-five patients were enrolled and treated in the current trial. Of the 53 patients whose responses were evaluable, 18 (34%) achieved a partial response, 27 (51%) had stable disease, and 8 (15%) developed disease progression as their best response to the treatment. The intent-to-treat median survival for all patients was 16.4 months and the time to progression was 4.8 months. All 55 patients were available for toxicity analysis (according to version 2.0 of the National Cancer Institute Common Toxicity Criteria). The most common Grade 3-4 toxic effect was neutropenia, which was reported to occur in 22 patients (40%). CONCLUSIONS: The combination of irinotecan and oxaliplatin appears to be safe and active when used to treat patients with metastatic colorectal cancer. Treatment results with this regimen were similar to those reported for other combined frontline chemotherapy regimens for colorectal cancer. When this particular regimen wa used, neutropenia was found to be the predominant toxicity.