Responses to Crizotinib Can Occur in High-Level MET-Amplified Non-Small Cell Lung Cancer Independent of MET Exon 14 Alterations.

Activation of the MET proto-oncogene (MET) highly sensitive to MET inhibition has recently been described in NSCLC through two mechanisms: high-level amplification of the MNNG HOS Transforming gene (MET) (usually expressed relative to the chromosome 7 centromere [CEP7] when using fluorescence in situ hybridization) and exon 14 alterations. As partial overlap of these biomarkers occurs, whether one is purely a surrogate for the other or both can represent true oncogenic driver states continues to be explored. Cases of MET inhibitor-sensitive NSCLC harboring exon 14 alterations without coincident amplification have already been described. Here we report two cases of MET inhibitor-sensitive NSCLC harboring high-level MET amplification (MET/CEP7 ratio ≥5) without coincident exon 14 alterations, suggesting that these two methods of MET activation can produce independent MET-addicted states in NSCLC. Molecular profiling designed to capture all cases of potentially MET-addicted NSCLC should address both activation mechanisms.