HLA-C and neoplasm: All cancer immunotherapies have drawbacks that are restricted by many factors, such as host genetics, MHC polymorphism, the abundance of tumor-infiltrated T cells, MHC deficiency, low tumor mutation burden, low abundance of neoantigens or TAA, etc. Immunopeptidomics will be the means to alleviate the effectiveness of immunotherapies through investigation of MHC ligandome landscape.