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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.

Abstract Background Accurate identification of the etiology of lower respiratory tract infections (LRTI) is crucial, particularly for immunocompromised patients with more complex etiologies. The advent of next-generation sequencing (NGS) has enhanced the effectiveness of pathogen detection. However, assessments of the clinical diagnostic value of targeted NGS (tNGS) in immunocompromised patients with LRTI are limited. Methods To evaluate the diagnostic value of tNGS in immunocompromised patients with LRTI, a total of 88 patients, of whom 54 were immunocompromised, were enrolled. These patients underwent tNGS testing of bronchoalveolar lavage fluid (BALF). Results from both metagenomic next-generation sequencing (mNGS) and conventional microbiological tests (CMT) were also available for all participants. The performance of tNGS was assessed by comparing its findings against mNGS, CMT, and the clinical composite diagnosis. Results In the cohort of 88 patients, tNGS showed comparable diagnostic value to mNGS and was significantly superior to CMT. Compared to CMT and composite reference standard, tNGS showed sensitivity of 94.55% and 90.48%, respectively. In immunocompromised patients, despite a more diverse pathogen variety, tNGS maintained similar sensitivity to mNGS and outperformed CMT. tNGS positively influenced etiologic diagnosis and antibiotic decision-making in 72.72% of cases, leading to a change in antibiotic regimen in 17.05% of cases. We also compared the detection of microbial nucleic acids by tNGS with mNGS and found that tNGS could identify 87.99% of the microbial nucleic acids identified by mNGS. Conclusion In summary, our study demonstrated that tNGS offers promising clinical diagnostic accuracy in immunocompromised patients, as evidenced by its favorable comparison with CMT, the composite reference standard, and mNGS.