Study to Evaluate the Effects of Panitumumab if Combined With Chemotherapy for 2nd Treatment of Colorectal Cancer

The purpose of this interventional study is to investigate whether there is evidence that panitumumab in combination with XELOX (capecitabine plus oxaliplatin) chemotherapy will safely increase progression-free survival, above that of XELOX alone in subjects with KRAS wild-type metastatic colorectal cancer who have not responded to or progressed after first line therapy with irinotecan and a fluoropyrimidine. Further Objectives Exploratory objectives may include investigation of potential correlations between the treatment regimen and epidermal growth factor receptor (EGFR) expression, detection of the functional genetic polymorphisms of the EGFR gene, EGFR gene amplification (FISH), EGFR downstream protein and gene expression parameters, proteomics and epigenetics.