The pig as a large preclinical model for therapeutic human anti-cancer vaccine development

Nana Haahr Overgaard, Thomas Mørch Frøsig, Simon Welner, M. Rasmussen, Mette Ilsøe, Maria Rathmann Sørensen, M. H. Andersen, S. Buus, Gregers Jungersen

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    Abstract

    Development of therapeutic cancer vaccines has largely been based on rodent models and the majority failed to establish therapeutic responses in clinical trials. We therefore used pigs as a large animal model for human cancer vaccine development due to the large similarity between the porcine and human immunome. We administered peptides derived from porcine IDO, a cancer antigen important in human disease, formulated in Th1-inducing adjuvants to outbred pigs. By in silico prediction 136 candidate IDO-derived peptides were identified and peptide-SLA class I complex stability measurements revealed 89 stable (t½ ≥ 0.5 hour) complexes with expressed SLA alleles. By IFN-γ ELISpot we showed that it was possible to break the peripheral tolerance and induce a cell-mediated response to an endogenous antigen. Mounting a proper Th1 response is highly dependent on peptide dose; we therefore designed a dose titration study with 15 Göttingen minipigs receiving intraperitoneal injections of either 1 µg, 10 µg or 100 µg of 30-31mer peptides covering the majority of IDO-derived potential cytotoxic T lymphocyte (CTL) epitopes. Peptides were formulated in CAF09, an adjuvant comprised of cationic DDA liposomes decorated with poly (I:C) and MMG as immune modulators. Interestingly, the 1 µg group was the only one showing responses to all immunization peptides following seven injections as determined by IFN-γ ELISpot. These data show that a reduction in dose can result in a highly specific Th1-biased response. To test the CTL functionality we designed an in vivo cytotoxicity assay, where purified autologous PBMCs fluorescently labelled and pulsed with IDO-derived target peptides were administered intravenously into each donor and killing capacity was measured by flow cytometry. All animals receiving 10 µg peptide immunizations showed specific killing of peptide-pulsed target cells one week post i.v. transfer with certain animals reaching close to 60% specific killing capacity in vivo.
    Original languageEnglish
    JournalEuropean Journal of Immunology
    Volume46
    Issue numberS1
    Pages (from-to)1102-1102
    Number of pages1
    ISSN0014-2980
    Publication statusPublished - 2016
    Event ICI 2016 International Congress of Immunology - Melbourne, Australia
    Duration: 21 Aug 201626 Aug 2016

    Conference

    Conference ICI 2016 International Congress of Immunology
    Country/TerritoryAustralia
    CityMelbourne
    Period21/08/201626/08/2016

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