<b><i>MET</i></b> Amplification and Response to MET Inhibitors in Stage IV Lung Adenocarcinoma

<b><i>Background:</i></b> Non-small-cell lung cancers with MET amplification may respond to c-MET inhibitors. <b><i>Methods:</i></b> We examined lung adenocarcinoma patients for mutations and amplification status of epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), ROS, <i>MET</i>. The clinical characteristics of patients with <i>MET</i> amplification and their responses to MET inhibitor therapy were studied. <b><i>Results:</i></b> Of the 76 patients analyzed, 5 were positive for <i>c-MET</i> gene amplification and 4 cases showed an intermediate result. For 12 patients who were EGFR positive, a <i>c-MET</i> analysis on secondary biopsy tissue was performed following disease progression. All 5 <i>c-MET</i>-positive patients were men. The age range in the study was 34-83 years. 4 of the 5 patients were started on crizotinib. 2 of these cases were positive following tyrosine kinase inhibitor therapy. 3 patients showed a response. 1 patient showed no response and was later found to have a concurrent T790M mutation. <b><i>Conclusions:</i></b> There are 2 categories of MET gene amplification in lung cancer patients, de novo and that secondary to TKI therapy. These patients can benefit from MET inhibitor therapy. Dual mechanisms of resistance, EGFR T790M mutation and c-MET amplification after TKI therapy, may suggest a poor prognosis.