Salmonella derived nanoparticles for cancer immunotherapy - Project Summary/Abstract The overwhelming public health burden of HPV-associated head and neck cancer (HNC) has created great demand for novel, broadly effective therapies with reduced treatment morbidity and improved long- term survival. The generation of tumor-specific CD8+ T cell immunity requires potent antigen cross-presentation by dendritic cells (DCs) since tumor cells do not efficiently present relevant CD8+ T cell epitopes. Because of this, innovative strategies to enhance cDC1s could robustly induce HPV-specific immunity and have great therapeutic potential in the treatment of HPV-associated HNC. FMS-like tyrosine kinase 3 ligand (Flt3L) is a cytokine that expands and differentiates DC precursors to murine cDC1s. Furthermore, IFNβ is a type I interferons, a major class of immune cytokines, that can act directly on CD8+ T cells to increase cytotoxicity and survival by increasing the expression of cytotoxic T cell markers. However, therapeutic potential of Flt3L and IFNβ is limited because of their short half-life and global distribution in vivo. We have overcome the described issues by generating a genetic fusion of Albumin (Alb) to Flt3L, named Albumin-Flt3L (Alb-Flt3L), and the genetic fusion of Alb to IFNβ, named Albumin- IFNβ (Alb- IFNβ). Alb has a long half-life due to FcRn mediated transcytolic recycling. Once cDC1s expand, they require a strong, tissue localized source of inflammation for activation, or they will present T cell epitopes without adequate costimulation, causing suppression. Enteric bacteria such as Salmonella serve as an ideal agent for tumor specific cDC1 activation as they can provide numerous pathogen- associated molecular patterns for cDC1 activation, and have been described to colonize the tumor efficiently likely due to hypoxia. However, the use of heat-inactivated Salmonella results in weak immunogenicity and potency. Therefore, something that is more potent and can penetrate tissue without the safety concerns of using live bacteria is needed. We overcame this issue through the usage of Salmonella derived outer membrane vesicles, which is considered safer and can effectively stimulate the immune system by presenting key immunogens from their parent bacteria while also showing promise as a drug delivery agent. By coating SOMV with 9RE7 peptide, we produced a novel approach of SOMV-9RE7 that serves as a safer and more effective drug delivery agent. The combination of Alb-IFNβ, Alb-Flt3L, and SOMV-9RE7 capitalizes on the strengths of these approaches, offering a synergistic strategy and valuable preclinical data for cancer treatment by targeting multiple mechanisms and addressing cancer resistance in HPV-associated head and neck cancers. Specifically, we will: Aim 1: Evaluate and compare the ability of Sal-9RE7 and SOMV-9RE7 to mediate tumor control and induce HPV E7-specific T cell immunity. Aim 2: Evaluate the potency of the combination treatment of Alb-Flt3L + Alb-IFNβ + SOMV-9RE7 to mediate tumor control and induce HPV E7-specific T cell response. Aim 3: Characterize the mechanism of Alb-Flt3L + Alb-IFNβ + SOMV-9RE7 combination in mediating antitumor immunity.
