Project Summary Vaccines targeting cancer neoantigens have the potential to enhance the magnitude, function, and duration of an anti-tumor T cell response, offering a promising strategy to improve response rates to immune checkpoint blockade (ICB). However, neoantigenic peptides are typically poorly immunogenic and even when administered in combination with an adjuvant do not elicit a sufficiently strong anti-tumor T cell response for maximal efficacy. This can be attributed to several factors, including poor lymphatic accumulation, low cellular uptake by antigen presenting cells (APCs), and inefficient cross-presentation to CD8+ T cells. The goal of this research is to design and evaluate a nanoparticle vaccine platform to potentiate cellular immunity against peptide neoantigens. We will do this through the design of nanoparticle vaccine technology that overcomes these drug delivery challenges through several, intertwined, methods: 1) Particles will be designed to allow simultaneous delivery of antigen and adjuvant to the same APC, resulting in coordinated expression of co-stimulatory markers and presentation of antigen, which will enhance downstream T cell activation. 2) Nanoparticles will be engineered with pH- responsive properties that promote cytosolic delivery of the antigen to increase cross presentation on MHC class I molecules, resulting in a stronger CD8+ T cell response. 3) A rapid and facile strategy for loading of peptide antigens will be employed, which will allow patient-specific neoantigenic peptides of diverse chemical properties to be efficiently integrated into the nanoparticle vaccine. 4) Nanoparticle properties will be optimized to allow for delivery of multiple, synergistically-acting adjuvants in order to further enhance T cell responses. We propose to accomplish this through two Specific Aims: 1) We will develop a nanotechnology for co-delivery of STING agonists and patient-specific peptide neoantigens. Peptide and nanoparticle properties will be optimized, the ability of the vaccine to activate an antigen-specific immune response will be assessed in vitro and in vivo, and efficacy will be evaluated using know murine neoantigens. 2) We will investigate adjuvant synergy between STING and toll-like receptor agonists by evaluating their ability to enhance antigen cross-presentation on APCs and induce antigen-specific T cell responses. Synergistic combinations will be co-loaded into the nanoparticle vaccine platform and efficacy will be evaluated in vitro and in vivo. We hypothesize that this new vaccine platform will generate a strong patient-specific, anti-tumor T cell response targeting a diversity of neoantigens, resulting in enhanced responses to ICB. This research will contribute to our growing understanding of how materials can be engineered to modulate immune responses and will result in a versatile new drug delivery technology that has potential to improve personalized cancer vaccines. This proposal also describes a ...