Patient with EGFR-mutant lung cancer harboring de novo MET amplification successfully treated with gefitinib combined with crizotinib

While 50% of lung adenocarcinoma patients in Asia have mutations in the epidermal growth factor recep-tor (EGFR) site, there are few patients with the EGFR mutation accompanied by de novo mesenchymal-epithelial transition (MET) amplification. Due to the low incidence rate, there is no consensus regarding treatment. Here, a case of a 62-year-old never smoker presented with EGFR Exon19del and de novo MET amplification. A radiographic examination and computed tomography (CT) imaging were conducted on the chest and middle abdomen. A pulmonary puncture was performed and a sample of the lung tissue was used for pathologic diagnosis. Immunohistochemistry was performed for the expression of CK, P40, P63, ttf-1, NapsinA, alk-d5f3, and ki-67 on the cancer cells. Craniocerebral magnetic resonance and whole body bone imaging were completed. Second-generation gene sequencing (next-generation sequencing [NGS]) and fluorescence in situ hybridization examination were also performed to further characterize the cancer cells. A radiographic examination was performed and revealed space-occupying lesions in the lungs. CT results revealed a mass in the upper lobe of the left lung. The pathologic diagnosis was non-small cell carcinoma T3N2M1a. Second-generation gene sequencing (NGS) indicated EGFR Exon 19del (p.E746_A750del, mutant abundance: 13.99%) with de novo MET amplification (CHR: q31.2, CN = 4.0). Fluorescence in situ hybridization examination confirmed MET amplification. Targeted therapy with gefitinib combined with crizotinib was administered as treatment. Four weeks later, the CT results revealed a substantial reduction in the lesion size. The patient was followed up with favorable complete recovery and no tumor-related symptoms. Although crizotinib is efficacious when used alone in follow-up treatment; however, these results of this case and others indicate that it is likely safe to use both drugs together in the case of drug resistance. (c) 2021 Elsevier Inc. All rights reserved.