Assessment of Baseline Clinical Predictive Factors of Response to Cetuximab-Irinotecan in Patients with Irinotecan-Refractory Metastatic Colorectal Cancer

Objective: To identify easily available predictive factors of response to cetuximab-irinotecan in patients with irinotecan-refractory metastatic colorectal cancer. Methods: Retrospective analysis of patients treated with cetuximab (400 mg/m 2 in week 1, 250 mg/m 2 in subsequent weeks) plus irinotecan (180 mg/m 2 every 2 weeks). We assessed demographic data, prior response to chemotherapy, number of metastatic sites, disease and metastatic disease durations, irinotecan-free interval and tumoral immunohistochemical epidermal growth factor receptor status. Results: We analyzed 311 patients. Objective response rate under cetuximab-irinotecan was 26%. In univariate analysis, prior response to irinotecan, presence of only 1 metastatic site, disease duration, metastatic disease duration and irinotecan-free interval equal or above median (24, 18 and 1.8 months, respectively) were predictive of response to cetuximab-irinotecan. Multivariate analysis confirmed independent predictive value of prior response to irinotecan, number of metastatic sites and disease duration. Conclusion: Prior response to irinotecan, number of metastatic sites and disease duration may contribute to better select patients suitable for cetuximab-irinotecan therapy.