Similarly, BRAF mutation was not predictive for treatment with cetuximab, but was a marker of poor prognosis in metastatic colorectal cancer patients (KRAS wild-type) that were randomly assigned to treatment with FOLFIRI (irinotecan, fluorouracil, leucovorin) with or without cetuximab in the CRYSTAL study (42). This evidence concerns the gene KRAS and metastatic colorectal cancer.