Purpose: We conducted a phase I and pharmacokinetic study of docetaxel in combination with irinotecan to determine the dose-limiting toxicity (DLT), the maximum-tolerated dose (MTD), and the dose at which at least 50% of the patients experienced a DLT during the first cycle, and to evaluate the safety and pharmacokinetic profiles in patients with advanced solid tumors.
Patients and methods: Patients with only one prior chemotherapy treatment (without taxanes or topoisomerase I inhibitors) for advanced disease were included in the study. Docetaxel was administered as a 1-hour IV infusion after premedication with corticosteroids followed immediately by irinotecan as a 90-minute IV infusion, every 3 weeks. No hematologic growth factors were allowed.
Results: Forty patients were entered through the following seven dose levels (docetaxel/irinotecan): 40/140 mg/m(2), 50/175 mg/m(2), 60/210 mg/m(2), 60/250 mg/m(2), 60/275 mg/m(2), 60/300 mg/m(2), and 70/250 mg/m(2). Two hundred cycles were administered. Two MTDs were determined, 70/250 mg/m(2) and 60/300 mg/m(2); the DLTs were febrile neutropenia and diarrhea. Neutropenia was the main hematologic toxicity, with 85% of patients experiencing grade 4 neutropenia. Grade 3/4 nonhematologic toxicities in patients included late diarrhea (7.5%), asthenia (15.0%), febrile neutropenia (22.5%), infection (7.5%), and nausea (5.0%). Pharmacokinetics of both docetaxel and irinotecan were not modified with the administration schedule of this study.
Conclusion: The recommended dose of docetaxel in combination with irinotecan is 60/275 mg/m(2), respectively. At this dose level, the safety profile is manageable. The activity of this combination should be evaluated in phase II studies in different tumor types.