Toward the development of multi-epitope p53 cancer vaccines: An in vitro assessment of CD8+ T cell responses to HLA class I-restricted wild-type sequence p53 peptides

Wild-type sequence (wt) p53 peptides are attractive candidates for broadly applicable cancer vaccines. Six HLA-A2 or HLA-A24-restricted wt p53 peptides were evaluated for their ex vivo immunogenicity and their potential for use in cancer vaccines. Peripheral blood mononuclear cells (PBMC) obtained from HLA-A⁎0201+ and/or HLA-A⁎2402+ normal donors and subjects with squamous cell carcinoma of the head and neck (SCCHN) were analyzed for p53 peptide-specific reactivity in ELISPOT IFN-γ assays. CD8+ T cells in 7/10 normal donors (HD) and 11/23 subjects with SCCHN responded to at least one of the wt p53 peptides. CD8+ T cell precursors responsive to wt p53 epitopes were detected in the circulation of most subjects with early disease, and an elevated blood Tc1/Tc2 ratio distinguished wt p53 peptide responders from non-responders. The identification of multiple wt p53 peptides able to induce cytolytic T lymphocytes in most subjects with cancer promotes the development of multi-epitope p53 vaccines.