To understand the molecular mechanism of tumorigenesis of pulmonary lymphoepithelioma-like carcinoma and explore potential therapeutic strategies, we investigated the genomic profiles and PD-L1 expression of 29 Chinese pulmonary lymphoepithelioma-like carcinoma patients at various stages. We performed capture-based targeted sequencing on tissue samples collected from 27 patients with sufficient samples using a panel consisting of 520 cancer-related genes, spanning 1.64 Mb of the human genome. We identified 184 somatic mutations in 109 genes from 26 patients. One patient had no mutations detected by this panel. Copy number variations were detected in 52% (14/27) of the patients, with a majority having advancedstage disease (10/14). Except for the detection of ERBB2 amplification and KRAS mutation in two patients, no other classic lung cancer driver mutations were detected. Interestingly, 78% (21/27) of the patients had mutations in epigenetic regulators. Of the 184 mutations identified, 51 occurred in 29 epigenetics-related genes. Furthermore, we performed PD-L1 immunohistochemistry staining using the Dako 22C3 assay and demonstrated that 69% (20/29) of the cohort had positive PD-L1 expression, of which three patients received and benefited from a PD-1 inhibitor. In conclusion, we elucidated a distinct genomic landscape associated with pulmonary lymphoepithelioma-like carcinoma with no classic lung cancer driver mutation but an enrichment of mutations in epigenetic regulators. The detection of high PD-L1 expression and lack of any canonical druggable driver mutations raises the potential of checkpoint immunotherapy for pulmonary lymphoepithelioma-like carcinoma.
Objective: NUT midline carcinoma (NMC), a rare type of squamous cell carcinoma, is genetically characterised by NUT midline carcinoma family member 1 (NUTM1) gene rearrangement. NMC can arise from the lungs; however, there is no standard for the management of primary pulmonary NMC. This study aimed to confirm the clinical features and report the treatments, especially with immune checkpoint inhibitors (ICIs), and outcomes of patients with primary pulmonary NMC. Methods: A retrospective review of patients with primary pulmonary NMC was performed in the First Affiliated Hospital of Guangzhou Medical University between January 2015 and December 2018. Clinical manifestations as well as radiographic and pathological findings were recorded. Whole-exome sequencing (WES), a predictor for ICI response, was used to determine the tumour mutational burden (TMB). Treatments, especially by immune checkpoint blockade, and patient survival were analysed. Results: Seven patients with primary pulmonary mass (four men and three women) with a mean age of 42 years (range, 23-74) who were diagnosed with NMC according to NUT immunohistochemistry staining were included for analysis. One patient had a rare fusion of CHRM5-NUTM1 by tumour sequencing. A wide range of TMB (1.75-73.81 mutations/Mbp) was observed. The initial treatments included chemotherapy (5/7, 71.4%), surgery (1/7, 14.3%), and radiotherapy (1/7, 14.3%). Five patients (5/7, 71.4%) received ICIs (programmed cell death protein 1 [PD1]/ programmed cell death ligand 1 [PDL1] monoclonal antibody) as second-or higher-line treatments. The median overall survival (OS) was 4.1 months (range, 1.5-26.7 months). Conclusions: Patients with primary pulmonary NMC have a poor prognosis and chemotherapy is often preferred. Checkpoint immunotherapy is a good option as the second-or higher-line treatment. TMB seems to be not associated with OS.
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