Identification of Two Novel HLA-A？0201-Restricted CTL Epitopes Derived from MAGE-A4

MAGE-A antigens belong to cancer/testis (CT) antigens that are expressed in tumors but not in normal tissues except testis and placenta. MAGE-A antigens and their epitope peptides have been used in tumor immunotherapy trials. MAGE-A4 antigen is extensively expressed in various histological types of tumors, so it represents an attractive target for tumor immunotherapy. In this study, we predicted HLA-A∗0201-restricted cytotoxic T lymphocyte (CTL) epitopes of MAGE-A4, followed by peptide/HLA-A∗0201 affinity and complex stability assays. Of selected four peptides (designated P1, P2, P3, and P4), P1 (MAGE-A4286-294, KVLEHVVRV) and P3 (MAGE-A4272-280, FLWGPRALA) could elicit peptide-specific CTLs both in vitro from HLA-A∗0201-positive PBMCs and in HLA-A∗0201/Kb transgenic mice. And the induced CTLs could lyse target cells in an HLA-A∗0201-restricted fashion, demonstrating that the two peptides are HLA-A∗0201-restricted CTL epitopes and could serve as targets for therapeutic antitumoral vaccination.