Rejection of large HPV-16 expressing tumors in aged mice by a single immunization of VacciMax® encapsulated CTL/T helper peptides

Pirouz M. Daftarian, Marc Mansour, Bill Pohajdak, Antar Fuentes-Ortega, Ella Korets-Smith, Lisa MacDonald, Genevieve Weir, Robert G. Brown, W. Martin Kast

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30 Scopus citations

Abstract

The incidence of cancer increases significantly in later life, yet few pre-clinical studies of cancer immunotherapy use mice of advanced age. A novel vaccine delivery platform (VacciMax®,VM) is described that encapsulates antigens and adjuvants in multilamellar liposomes in a water-in-oil emulsion. The therapeutic potential of VM-based vaccines administered as a single dose was tested in HLA-A2 transgenic mice of advanced age (48-58 weeks old) bearing large palpable TC1/A2 tumors. The VM-based vaccines contained one or more peptides having human CTL epitopes derived from HPV 16 E6 and E7. VM formulations contained a single peptide, a mixture of four peptides or the same four peptides linked together in a single long peptide. All VM formulations contained PADRE and CpG as adjuvants and ISA51 as the hydrophobic component of the water-in-oil emulsion. VM-formulated vaccines containing the four peptides as a mixture or linked together in one long peptide eradicated 19-day old established tumors within 21 days of immunization. Peptide-specific cytotoxic cellular responses were confirmed by ELISPOT and intracellular staining for IFN-γ producing CD8+ T cells. Mice rendered tumor-free by vaccination were re-challenged in the opposite flank with 10 million HLF-16 tumor cells, another HLA-A2/E6/E7 expressing tumor cell line. None of these mice developed tumors following the re-challenge. In summary, this report describes a VM-formulated therapeutic vaccine with the following unprecedented outcome: a) eradication of large tumors (> 700 mm3) b) in mice of advanced age c) in less than three weeks post-immunization d) following a single vaccination.

Original languageEnglish (US)
Article number26
JournalJournal of translational medicine
Volume5
DOIs
StatePublished - Jun 7 2007

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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