Identification of SART3-derived peptides having the potential to induce cancer-reactive cytotoxic T lymphocytes from prostate cancer patients with HLA-A3 supertype alleles

SART3-derived peptides applicable to prostate cancer patients with HLA-A3 supertype alleles were identified in order to expand the possibility of an anti-cancer vaccine, because the peptide vaccine candidates receiving the most attention thus far have been the HLA-A2 and HLA-A24 alleles. Twenty-nine SART3-derived peptides that were prepared based on the binding motif to the HLA-A3 supertype alleles (HLA-A11, -A31, and -A33) were first screened for their recognizability by immunoglobulin G (IgG) of prostate cancer patients and subsequently for the potential to induce peptide-specific cytotoxic T lymphocytes (CTLs) from HLA-A3 supertype+ prostate cancer patients. As a result, five SART3 peptides were frequently recognized by IgG, and two of them—SART3 511-19 and SART3 734-42—efficiently induced peptide-specific and cancer-reactive CTLs. Their cytotoxicity toward prostate cancer cells was ascribed to peptide-specific and CD8+ T cells. These results indicate that these two SART3 peptides could be promising candidates for peptide-based immunotherapy for HLA-A3 supertype+ prostate cancer patients.