The role of cMet in non-small cell lung cancer resistant to EGFR-inhibitors: did we really find the target?

The advent of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) represented the most important innovation in NSCLC treatment over the last years. However, despite a great initial activity, secondary mutations in the same target, or different alterations in other molecular pathways, inevitably occur, leading to the emergence of acquired resistance, in median within the first year of treatment. In this scenario, the mesenchymal-epidermal transition (cMET) tyrosine kinase receptor and its natural ligand, the hepatocyte growth factor (HGF), seem to play an important role. Indeed either the overexpression or the amplification of cMET, as well as the overexpression of the HGF, have been reported in a substantial subgroup of NSCLC patients resistant to EGFR-TKIs. Several cMET-inhibitors have been developed as potential therapeutic candidates, and are currently under investigation in clinical trials. These compounds include both monoclonal antibodies and TKIs, and most of them have been investigated as dual combinations including an anti-EGFR TKI, to improve the efficacy of the available treatments, and ultimately overcome acquired resistance to EGFR-inhibitors.