Phase II study of combination chemotherapy with biweekly cetuximab and irinotecan for wild-type KRAS metastatic colorectal cancer refractory to irinotecan, oxaliplatin, and fluoropyrimidines.

The aim of this study is to prospectively evaluate the efficacy of combination chemotherapy with every second week cetuximab and irinotecan in patients with pretreated metastatic colorectal cancer harboring wild-type KRAS. Patients with wild-type KRAS metastatic colorectal cancer that had progressed after chemotherapy with irinotecan, oxaliplatin, and fluoropyrimidine were included. Cetuximab was administered at 500 mg/m(2) biweekly with irinotecan. The primary endpoint was response rate. The pharmacokinetics of cetuximab was also evaluated in 5 patients. From May 2009 to February 2010, a total of 31 patients were enrolled from five institutions. One patient was not eligible. Among the 30 patients who were treated with biweekly cetuximab plus irinotecan, partial response was observed in 9 patients. The objective response rate was 30.0% (95% confidence interval [CI], 14.7%-49.4%) and the disease control rate (complete response, partial response, or stable disease) was 76.7% (95% CI, 57.7%-90.0%). The median progression-free survival was 5.3 months and median overall survival was 10.8 months. Grade 3 skin toxicity was observed in 3 patients (10.0%) and one treatment related death due to pneumonia was observed. Combination chemotherapy with biweekly cetuximab and irinotecan was effective for pretreated metastatic colorectal cancer with wild-type KRAS.