He was formerly a Scientific Member of Basel Institute for Immunology, Switzerland, where he studied basic immunology. At Osaka University, Dr. Oka and his colleagues identified cytotoxic T lymphocyte (CTL) epitopes of WT1 protein, which showed that WT1 is a novel cancer antigen. Subsequently, they demonstrated that WT1-targeting immunotherapy, such as WT1 peptide vaccine, has a therapeutic potential for various kinds of malignancies. Dr. Oka’s main interest and research field is cancer immunology and immunotherapy.