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Immunogenic neoantigens derived from somatic mutations in cancer have been identified through clinical studies with the cloning of tumor-infiltrating T cells, and cancer driver gene mutation-derived epitopes have been reported; however, these are rare. At present, the validation of epitopes predicted in silico is difficult as human T-cell clonal diversity cannot be reproduced in vitro or in experimental animal models. To confirm the epitope peptides presented by human leukocyte antigen (HLA) class I molecules predicted in silico, biochemical methods such as major histocompatibility complex (MHC) stabilization assays and mass spectrometry-mediated identification have been developed based on HLA-A*02:01 monoallelic T2 cells and HLA-C*01:02 monoallelic LCL721.221 cells. Therefore, in the present study, to prevent confusion due to peptide cross-presentation among HLA molecules, HLA class I monoallelic B-cell clones were generated from the TISI cell line by knocking out HLA-ABC and TAP2, and knocking in HLA alleles. To explore cancer driver mutations as potential targets for immunotherapy, exome sequencing data from 5,143 patients with cancer enrolled in a comprehensive genome analysis project at the Shizuoka Cancer Center were used to identify somatic amino acid substituted mutations and the 50 most frequent mutations in five genes, TP53, EGFR, PIK3CA, KRAS and BRAF, were identified. Using NetMHC4.1, the present study predicted whether epitopes derived from these mutations are presented on major HLA-ABC alleles in Japanese individuals and synthesized 138 peptides for MHC stabilization assays. The authors also attempted to examine the candidate epitopes at physiological temperatures by using antibody clone G46-2.6, which can detect HLA-ABC, independent of ß2-microglobulin association. In the assays, although the peptide-induced HLA expression levels were associated with the predicted affinities, the respective HLA alleles exhibited varying degrees of responsiveness, and unexpectedly, p53-mutant epitopes with predicted weak affinities exhibited strong responses. These results suggested that MHC stabilization assays using completely monoallelic HLA-expressing B-cell lines are useful for evaluating the presentation of neoantigen epitopes. [ABSTRACT FROM AUTHOR]

Primary cancer of the trachea is rare and accounts for only 0.1-0.4% of all newly diagnosed respiratory tract cancers, worldwide. In the present study, a case of primary tracheal malignant melanoma, a particularly rare type of cancer, is reported. A 68-year-old male presented with a cough and bloody sputum. A chest computed tomography scan revealed a 25x20x15-mm tracheal tumor, located immediately above the carina, which reduced the cross-sectional area of the trachea by ~90%. Histopathological analysis of biopsy specimens determined a diagnosis of malignant melanoma. The patient was treated with argon plasma coagulation and chemoradiotherapy, which restored airway patency, however, metastasis was detected in the lungs. The patient refused further treatment and received palliative care. Subsequently, the patient succumbed to the disease within four months. Thus, although primary malignant melanoma of the trachea is extremeley rare, the possibility should be considered during diagnosis. [ABSTRACT FROM AUTHOR]