Coexistence of MET exon 14 mutations with EGFR mutations in non-small cell lung cancer.

e20636 Background: Activation of MET oncogene as the result of amplification or activation MET exon 14 mutations represents an emerging molecular target for non-small cell lung cancer (NSCLC) treatment. MET exon 14 mutations account for 1.0% in Chinese NSCLC patients. However, few data have been reported on the coexisting of MET exon 14 mutations and EGFR mutations in NSCLC. Moreover, the clinicopathological characteristics and targeted therapy of these MET/ EGFR-coexisting patients remain elusive. Methods: Next-generation sequencing was performed on the DNA of 969 patients and Sanger sequencing was conducted on cDNA of 621 patients for MET exon 14 mutations in NSCLCs. EGFR mutations were determined by direct DNA sequencing. Results: Fifteen patients harbored positive MET exon 14 mutations. Frequency of concomitant EGFR and MET exon 14 mutations was 0.2%(3/1590). 3 patients with concomitant MET exon 14 mutation and EGFR activating mutation were all female, never smokers and adenocarcinoma. Their stagings were stageⅠB (n = 1) and stage Ⅳ(n = 2). The stage ⅠB patient harboring concomitant MET exon 14 skipping and EGFR L858R mutation did not relapse 2 years after operation. The other two stage Ⅳ patients received first-line gefitinib. Case one harbored concomitant MET exon 14 point mutations (IVS13-36G > A) and EGFR exon 19 deletion, and showed resistance to gefitinib with progression free survival(PFS) of 2 weeks and overall survival(OS) of 1 month. Case two had concomitant MET exon 14 point mutations (IVS13-36G > A) and EGFR L858R mutation. Meanwhile, she also had both METamplification and c-Met overexpression at the baseline. She showed partial response (PR) to gefitinib with 3.8 months PFS. Then she was enrolled in a clinical trial (NCT02374645) to receive volitinib plus gefitinib on December 20, 2016. Initial response was good PR on January 24, 2017. Only grade 1 rash was observed. Conclusions: Coexisting MET exon 14 /EGFR mutation is an uncommon molecular event in NSCLC patients. Such coexisted patients might show relative resistance to EGFR inhibitor. However, combination of MET and EGFR inhibitors will be potentially a good strategy to overcome such a relative resistance for MET exon 14 /EGFR co-mutant patients.