HLA-DRB1 and cancer: To screen TAA-derived Th-cell epitopes for peptide-based cancer immunotherapy in as many Japanese as possible, we generated HLA-DR4 Tgm expressing HLA-DRA*01:01/HLA*DRB1*04:05 genes of which allele frequency is 13.6% in the Japanese population, that is, about one forth of Japanese have this HLA-DR molecule.