Retrospective analysis of cetuximab monotherapy for patients with irinotecan-intolerant metastatic colorectal cancer.

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.