Background: The efficacy and safety of cetuximab for irinotecan-intolerant patients has not yet been evaluated in detail.
Methods: We retrospectively analyzed the efficacy and safety of cetuximab monotherapy for patients with metastatic colorectal cancer (MCRC) that was intolerant to irinotecan.
Results: Among 105 patients who received cetuximab-containing chemotherapy until March 2010, 22 patients were treated with cetuximab monotherapy due to irinotecan intolerance. Cetuximab was given at the approved dosage to all patients. The performance status was 2 or 3 in 17 patients (77%). All but 1 patient had wild-type KRAS tumors. The causes of irinotecan intolerance were icterus (n = 9; 41%; median serum total bilirubin, 6.3 mg/dl), symptomatic peritoneal metastasis or obstruction (n = 8; 36%), and thrombocytopenia (n = 1; 5%). Four patients (18%) refused irinotecan due to previous irinotecan-associated toxicity. Two patients achieved a partial response with an apparent drop of serum bilirubin, for a response rate of 9.1%. The median progression-free survival and overall survival were 1.6 and 3.5 months, respectively. No grade 3 or 4 adverse events or treatment-related deaths were experienced.
Conclusion: Cetuximab monotherapy for irinotecan-intolerant MCRC is feasible. However, the overall efficacy was modest in the present cohort, despite the fact that most of the patients had wild-type KRAS tumors; further effective therapies should be evaluated to improve the prognosis of this patient population.