Clinical implications of MET gene copy number in lung cancer

MET, the receptor for HGF, has recently been identified as a novel promising target in several human malignancies, including non-small-cell lung cancer (NSCLC). Deregulation of the HGF/MET signaling pathway can occur via different mechanisms, including HGF and/or MET overexpression, MET gene amplification, mutations or rearrangements. While the role of MET mutations in NSCLC is not yet fully understood, MET amplification emerged as a critical event in driving cell survival, with preclinical data suggesting that MET-amplified cell lines are exquisitely sensitive to MET inhibition. True MET amplification, which has been associated with poor prognosis in different retrospective series, is a relatively uncommon event in NSCLC, occurring in 1-7% of unselected cases. Nevertheless, in highly selected cohorts of patients, such as those harboring somatic mutations of the EGF receptor (EGFR) with acquired resistance to EGFR tyrosine kinase inhibitors (TKIs), MET amplification can be observed in up to 20% of cases. Preclinical data suggested that a treatment approach including a combination of EGFR and MET TKIs could be an effective strategy in this setting and led to the clinical investigation of multiple MET TKIs in combination with erlotinib. Results from ongoing and future trials will clarify the role of MET TKIs for the treatment of NSCLC and will provide insights into the most appropriate timing for their use.