Panitumumab in Combination With Cytotoxic Chemotherapy for the Treatment of Metastatic Colorectal Carcinoma

The fully human anti-epidermal growth factor receptor (EGFR) monoclonal antibody panitumumab has been shown to improve progression-free survival when administered as a monotherapy for patients with chemotherapy-refractory metastatic colorectal cancer (mCRC) and is approved in this setting. Two large randomized clinical trials have investigated panitumumab in combination with 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) as a first-line therapy for mCRC and 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) as a second-line therapy for mCRC. In these studies, the combination of panitumumab with FOLFOX or FOLFIRI resulted in improved progression-free survival compared with FOLFOX or FOLFIRI alone. Improved tumor response was also observed with the addition of panitumumab to FOLFIRI. As in monotherapy trials, the clinical benefits associated with panitumumab treatment were confined to patients with wild-type KRAS tumors, further showing the validity of KRAS mutational status as a predictive biomarker in mCRC. In addition to KRAS mutational status, a number of other potential predictive biomarkers are currently being investigated in mCRC and may eventually help identify patients who are likely to benefit from treatment with anti-EGFR monoclonal antibodies. Toxicities observed during treatment with panitumumab combined with FOLFOX or FOLFIRI were generally manageable and commonly included skin toxicities and gastrointestinal toxicities. Because it can lead to dose delays, dose reductions, and discontinuation, physicians and patients should carefully manage skin toxicity. Overall, the results of these two studies show that panitumumab improves outcomes when added to FOLFOX or FOLFIRI among patients with mCRC with wild-type KRAS.