title: Immunogenicity of GX301 cancer vaccine: Four (telomerase peptides) are better than one.
abstract: Peptide540-548, peptide611-626, peptide672-686 and peptide766-780, which are derived from human telomerase, constitute the immunogenic component of the GX301 cancer vaccine. The relative immunogenicity of these peptides is unknown, thus it is unsure whether their combined use offers real advantages over single peptide stimulation. Hence, this study compared the number of specific immune responses and responders to each peptide, as well as to their mixture (meaning the co-presence of the 4 peptides in the same culture well), achieved after ex vivo stimulation of PBMC from 21, HLA-A2+ (n.11) or HLA-A2- (n.10), healthy donors. The study was performed on freshly collected PBMC (T0) and on PBMC stimulated for 10 d with single peptides or their mixture (T1). Peptide-specific immune responses were analyzed by Elispot and cytokine intracellular staining by flow cytometry. The results showed that each peptide induced specific immune responses in some subjects, with different panels of responders among the peptides. Moreover, the numbers of responses and responders to the single peptides or their mixture were comparable. Importantly, the overall number of responders to the 4 peptides was higher than to each single peptide, or to their mixture, both at T0 and T1. These data demonstrate the immunogenicity of each of the 4 GX301 telomerase peptides. Moreover, they show the advantage of multi-peptide over single peptide stimulation, providing a clear support to their combined administration in vaccination protocols. However, the data pose a warning against peptide administration as a mixture due to possible interference phenomena during antigen presentation processes.
authors.affiliation: a Centre of Excellence for Biomedical Research ; University of Genoa ; Genoa , Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Fenoglio
authors.forename: Alessia
authors.initials: A
authors.lastname: Parodi
authors.forename: Rosa
authors.initials: R
authors.lastname: Lavieri
authors.forename: Francesca
authors.initials: F
authors.lastname: Kalli
authors.forename: Francesca
authors.initials: F
authors.lastname: Ferrera
authors.forename: Augusto
authors.initials: A
authors.lastname: Tagliamacco
authors.forename: Andrea
authors.initials: A
authors.lastname: Guastalla
authors.forename: Maria Giuseppina
authors.initials: MG
authors.lastname: Lamperti
authors.forename: Mauro
authors.initials: M
authors.lastname: Giacomini
authors.forename: Gilberto
authors.initials: G
authors.lastname: Filaci
mesh_terms: D000328:Adult; D019496:Cancer Vaccines / Q000276:immunology*; D045744:Cell Line, Tumor; D005260:Female; D005805:Genes, MHC Class I / Q000276:immunology; D015789:HLA-A2 Antigen / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000276:immunology*; D019098:Telomerase / Q000276:immunology*
chemical_list: D019496:Cancer Vaccines; D015789:HLA-A2 Antigen; D010455:Peptides; D019098:Telomerase
keywords: CIS, cytokine intracellular staining; CTL, cytotoxic T lymphocytes; FITC, fluorescein isothiocynate; GX301; IFNγ, interferon-gamma; PBMC, peripheral blood mononuclear cells; PBS, phosphate buffered saline; cancer vaccines; cytokine intracellular staining; elispot; immunogenicity; mAb, monoclonal antibody; telomerase