Abstract
BACKGROUND: Mesenchymal epithelial transition factor (MET) variant is an independent prognostic factor for worse prognosis in patients with lung cancer or gastroesophageal adenocarcinoma. MET gene variants can be regarded as a subtype of melanoma but there is a lack of studies regarding the frequency of MET genetic alterations and the efficacy of immunotherapy in melanoma patients. The purpose of this study is to explore potential therapeutic strategies for melanoma subtypes with MET alterations. METHODS: A total of 1751 malignant melanomas were analyzed to illustrate the landscape of MET mutations. We collected 55 melanoma cases from multicenter for a retrospective cohort from 2010 to 2023. We analyzed the impact of MET amplification on the efficacy of immunotherapy in the retrospective cohort after propensity score matching (PSM) and a pancancer cohort. CIBERSORT was used to evaluate the immune infiltration. RESULTS: There were no instances of MET 14 exon skipping, and only instances of MET amplification were found in the 1751 melanomas and our retrospective cohort. Cox proportional hazards model analysis showed that MET amplification (P = 0.006) was significantly associated with poorer overall survival (OS) in patients who received immunotherapy as the first-line treatment. Compared with patients with MET amplification, patients in the negative control (NC) group had a significantly better OS (P = 0.022) after PSM. Analysis of 1661 pancancer cases with the MSK-IMPACT assay showed that patients receiving immunotherapy in the MET amplification group had a trend toward worse OS than those without MET amplification (P = 0.025). CONCLUSIONS: This database analysis showed that the main type of MET mutation is amplification in malignant melanoma. MET-amplified solid tumors might be considered for targeted therapy, as MET amplification can be regarded as a risk factor affecting the prognosis of patients with tumors treated with immunotherapy.