American society of clinical oncology provisional clinical opinion: Testing for KRAS gene mutations in patients with metastatic colorectal carcinoma to predict response to anti-epidermal growth factor receptor monoclonal antibody therapy

Purpose An American Society of Clinical Oncology (ASCO) provisional clinical opinion (PCO), offers timely clinical direction to ASCO's oncologists following publication or presentation of potentially practicechanging data from major studies. This PCO addresses the utility of KRAS gene mutation testing in patients with metastatic colorectal carcinoma to predict response to anti- epidermal growth factor receptor (anti-EGFR) monoclonal antibody (MoAb) therapy with cetuximab or panitumumab (see Note). Clinical Context Recent results from phase II and III clinical trials demonstrate that patients with metastatic colorectal cancer benefit from therapy with monoclonal antibodies directed against the EGFR, when used either as monotherapy or combined with chemotherapy. Retrospective subset analyses of the data from these trials strongly suggest that patients who have KRAS mutations detected in codon 12 or 13 do not benefit from this therapy. Recent Data Five randomized controlled trials of cetuximab or panitumumab have evaluated outcomes for patients with metastatic colorectal carcinoma in relation to KRAS mutational status as no mutation detected (wild type) or abnormal (mutated). Another five single-arm studies have retrospectively evaluated tumor response according to KRAS status. Provisional Clinical Opinion Based on systematic reviews of the relevant literature, all patients with metastatic colorectal carcinoma who are candidates for anti-EGFR antibody therapy should have their tumor tested for KRAS mutations in a CLIA-accredited laboratory. If KRAS mutation in codon 12 or 13 is detected, then patients with metastatic colorectal carcinoma should not receive anti-EGFR antibody therapy as part of their treatment.