Purpose: To evaluate the efficacy and tolerance of combined irinotecan and oxaliplatin in patients with advanced colorectal cancer pretreated with leucovorin-modulated fluoropyrimidines.
Patients and methods: Thirty-six patients with metastatic colorectal cancer, who progressed while receiving or within 6 months after discontinuing palliative chemotherapy with fluoropyrimidines/leucovorin, were enrolled onto this study. Treatment consisted of oxaliplatin 85 mg/m2 on days 1 + 15 and irinotecan 80 mg/m2 on days 1 + 8 + 15 every 4 weeks. Depending on the absolute neutrophil counts (ANC) on the day of scheduled chemotherapeutic drug administration, a 5-day course of granulocyte colony-stimulating factor (G-CSF) 5 microg/kg/d was given.
Results: The overall response rate was 42% for all 36 assessable patients (95% confidence interval, 26% to 59%), including two complete remissions (6%). Thirteen additional patients (36%) had stable disease, and only eight (22%) progressed. The median time to treatment failure was 7.5 months (range, 1 to 13.5+ months). After a median follow-up time of 14 months, 19 patients (53%) are still alive. Hematologic toxicity was commonly observed, although according to the ANC-adapted use of G-CSF (in 31 patients during 81 of 174 courses), it was generally mild: grade 3 and 4 granulocytopenia occurred in only five and two cases, respectively. The most frequent nonhematologic adverse reactions were nausea/emesis and diarrhea, which were rated severe in 17% and 19%, respectively.
Conclusion: Our data suggest that the combination of irinotecan and oxaliplatin with or without G-CSF has substantial antitumor activity in patients with progressive fluoropyrimidine/leucovorin-pretreated colorectal cancer. Overall toxicity was modest, with gastrointestinal symptoms constituting the dose-limiting side effects. Further evaluation of this regimen seems warranted.