Multi-Compartmental Delivery Systems for Peptide and DNA Vaccines in Melanoma Immunotherapy

The vaccine delivery systems containing adjuvants modulate magnitude, breadth, quality, and longevity of immune responses to antigen vaccinations aimed to induce cell-mediated immunity. For vaccines targeting tumor antigens, adjuvant-based delivery systems are necessary to overcome various tolerance mechanisms and facilitate induction of cytotoxic T lymphocytes (CTLs) that can traffic to and lyse malignant cells. The objective of this doctoral thesis project was to develop a multi-compartmental vaccine delivery system for safe and efficient delivery of a variety of melanoma antigens for immunotherapy.;Water-in-oil-in-water (W/O/W) multiple emulsions-based multi-compartmental vaccine delivery systems containing the gp100 peptide or hgp100 plasmid DNA was prepared by a two-step emulsification method. Morphological evaluation of the W/O/W multiple emulsions demonstrated that the oil-droplets were homogenously dispersed with an antigen encapsulated in an inner aqueous-phase. In addition, in vitro transfection and transgene expression ability of the hgp100 plasmid DNA vaccine was investigated in murine immune cells. In vivo immunization effectiveness of the novel gp100 antigen vaccines was evaluated in the murine B16 melanoma model. Immunization of C57BL/6 mice using the W/O/W multiple emulsions encapsulated gp100 antigen vaccines provided increased protection against tumor challenge. In addition, serum Th1 cytokine levels and immuno-histochemistry of excised tumor tissues indicated the vaccine evoked of antigen-specific cell-mediated anti-tumor immunity. Moreover, the newly developed vaccine formulation was well tolerated in vivo. Further enhancement of immune responses by preventing adenosine-mediated immune-suppression was investigated by concurrent administration of adenosine A2A receptor antagonist such as caffeine. A considerable increase in protection against tumor challenge due to co-administration of caffeine with gp100 peptide or hgp100 plasmid DNA immunization was not observed. Therefore, adjunct therapy using potent adenosine A2A receptor antagonists such as ZM-241385 or istradefylline (KW-6002) is recommended to validate the hypothesis.;The W/O/W multiple emulsions-based vaccine formulation efficiently delivers the gp100 peptide and hgp100 plasmid DNA antigens to evoke cell-mediated anti-tumor immunity and protects C57BL/6 mice against subsequent tumor challenge. Thus, the novel multi-compartmental vaccine delivery system offers an alternate, safe antigen delivery for melanoma immunotherapy.