A Novel c-Mesenchymal-Epithelial Transition Factor Intergenic Fusion Response to Crizotinib in a Chinese Patient With Lung Adenocarcinoma: A Case Report

Background The c-mesenchymal-epithelial transition factor (C-MET) is an oncogene encoding a tyrosine kinase receptor that plays an important role in tumor growth and metastasis. The National Comprehensive Cancer Network (NCCN) guidelines have approved carbatinib/crizotinib for advanced non-small cell lung cancer (NSCLC) patients with MET exon 14 skipping. Methods In June 2020, the Department of Respiratory and Critical Care Medicine of Peking University People's Hospital admitted a 72-year-old male patient with lung adenocarcinoma (LADC) with a history of interstitial lung disease secondary to antineutrophil cytoplasmic antibody-associated vasculitis. Genetic examination by next-generation sequencing showed an intergenic fusion of MET, and crizotinib was administered on August 14, 2020. Follow-up showed that tumor volume was significantly reduced. However, crizotinib was discontinued in November 2020 because of the patient's worsening interstitial lung disease, and CT scans showed continued partial response (PR) for 5 months. In April 2021, right lower lobe mass progressed, and disease progression was considered. Conclusion This was the first case of a patient with LADC with MET intergenic fusion who significantly benefited from crizotinib. Even after crizotinib was discontinued for 5 months, the patient continued exhibiting PR, suggesting that MET intergenic fusion may have carcinogenic activity in LADC and was sensitive to crizotinib.