A Therapeutic Whole-Tumor-Cell Vaccine Covalently Conjugated with a TLR7 Agonist

Abstract

A single-protein or -peptide vaccine is not sufficient to arouse immune responses in cancer therapy. A whole-tumor-cell vaccine with complete cancer cell antigens and all conformations elicits robust immune responses and is a promising method for the treatment of advanced malignant tumors. In this study, we used 5-azacitidine to stimulate B16-F10 melanoma cells to express toll-like receptor (TLR) 3 on the cell surface and then chemically linked SZU-106, a small-molecule TLR7 agonist, to the cell surface with a pegylated linker to produce a novel whole-tumor-cell vaccine, abbreviated as Aza-BFcell-106. The vaccine stimulated mouse splenic lymphocytes and bone marrow-derived dendritic cells to secrete cytokines, promoted the maturation of dendritic cells and enhanced the capability of dendritic cells to present antigens. In a mouse model of melanoma, the vaccine effectively inhibited tumor growth, decreased tumor volume and prolonged survival. Further combination of the vaccine with a chemokine inhibitor, reparixin, significantly increased the infiltration of CD4+ and CD8+ T cells into the tumor environment, while the antitumor effect was significantly enhanced. The whole-tumor-cell vaccine Aza-BFcell-106 induced immune-activating responses in both in vitro and in vivo experiments, indicating that this vaccine has great potential to treat advanced malignant tumors.