Signal peptide (SP) domains have a common motif but also sequence specific features. This knowledge was mainly ignored by immunologists who considered SP as generic, short-lived, targeting sequences. Consequently, while SP-derived MHC class I, class II and HLA-E epitopes have been isolated, their use as antigen-specific vaccine candidates (VCs) was mostly neglected. Recently we demonstrated the rational of selecting entire SP domains as multi-epitope long peptide VCs based on their high T and B-cell epitope densities. This review summarizes preclinical and clinical results demonstrating the various advantages of human SP domain VCs derived from both bacterial and tumor antigens. Such vaccine design provides for a straightforward, yet unique immunotherapeutic means of generating robust, non-toxic, diversified, combined antigen-specific CD4+/CD8+ T/B-cell immunity, irrespective of patient HLA repertoire also in disease associated transporter-associated with antigen processing (TAP) deficiencies. Subsequent clinical trials will further assess the full potential of this approach.
Keywords: ADCC, antibody-dependent cell-mediated cytotoxicity; AE, adverse events; APC, antigen presenting cells; DC, dendritic cells; ER, endoplasmic reticulum; ImMucin; LP, long peptide; MHC; MHC, major histocompatibility complex; MM, multiple myeloma; MUC1; PBMC, peripheral blood mononuclear cells; SP, signal peptide; SPP, signal peptide peptidase; SPase, signal peptidase; T-cell; TAA, tumor associated antigen; TAP, transporter-associated with antigen processing; VC, vaccine candidate; antibodies; cancer; hGM-CSF, human granulocyte-macrophage colony-stimulating factor; long peptide; signal peptide; tuberculosis; vaccine.