561 Background: Weekly cetuximab and irinotecan is a standard regimen in heavily pretreated patients with metastatic colorectal cancer (MCRC). The aim of this study was to prospectively evaluate the efficacy of combination chemotherapy with biweekly cetuximab and irinotecan in patients with pretreated MCRC harboring wild-type KRAS. Methods: Patients with wild- type KRAS MCRC that had progressed after chemotherapy with irinotecan, oxaliplatin, and fluoropyrimidine were included in this study. Cetuximab was administered at 500 mg/m2 biweekly with irinotecan. The primary endpoint was response rate. The secondary endpoints included adverse events, progression-free survival, and overall survival. The pharmacokinetics of cetuximab was also evaluated in five patients. Results: From May, 2009 to February, 2010, a total of 31 patients were enrolled from five institutions. One patient was not eligible. Among the 30 assessable patients, ECOG PS was 0 in 12, 1 in 16, and 2 in two 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, 61.4-92.3). The median progression-free survival was 5.3 months (95%CI, 3.4-7.3). Grade 3 skin toxicity was observed in 3 patients (10%), and treatment related death due to pneumonia occurred in one patient. Conclusions: The efficacy data are similar to those of standard dose of cetuximab plus irinotecan. Combination chemotherapy with biweekly cetuximab and irinotecan is effective for pretreated metastatic wild-type KRAS MCRC. No significant financial relationships to disclose.
Therapeutic Response of Metastatic Colorectal Cancer Harboring aKRASMissense Mutation After Combination Chemotherapy With the EGFR Inhibitor Panitumumab