Oxidative Stress-Induced Immunogenic Cell Death Enhances Whole-Cell Vaccine Efficacy in a Syngeneic Pancreatic Cancer Model

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer, with limited therapeutic options and extremely high mortality rates. While immune checkpoint blockade (ICB) therapy is effective in many types of human cancers, responses in PDAC patients remain poor, partly due to the weak immunogenicity of PDAC tumors. We hypothesized that a whole-cell PDAC vaccine could improve anti-tumor responses if optimized to expose a more stimulatory repertoire of tumor antigens. To test this, we used murine Panc02 pancreatic cancer cells to screen several stress-inducing treatments (UV, hypoxia, heat shock, and hydrogen peroxide [H2O2]), among which low-dose oxidative stress (0.05% H2O2 for 2h) was identified as the optimal inducer of immunogenic cell death (including increased surface calreticulin, ERp57 exposure, HMGB1 release and MHC class I expression). We then prepared a whole-cell vaccine of fixed H2O2-treated Panc02 cells, which induced robust tumor-specific immunity in C57BL/6 mice bearing syngeneic Panc02 tumors. Vaccine-treated mice displayed a significant increase in tumor-reactive IFN{gamma}+ T cells, as well as extensive tumor infiltration by CD4 + and CD8 + T cells and NCR1+ NK cells. When used prophylactically, the vaccine significantly delayed tumor growth and extended survival, whereas therapeutic application markedly slowed tumor progression. Importantly, combining the whole-cell Panc02 vaccine with anti-PD-1 therapy induced complete tumor regression in a subset of animals. Together, these data demonstrate that controlled oxidative stress can convert autologous tumor cells into an effective whole-cell vaccine without the need for genetic modification or prior neoantigen identification, offering a scalable strategy for personalized immunotherapy in PDAC. STATEMENT OF SIGNIFICANCEThis study demonstrated that oxidative stress-induced immunogenic cell death reprograms pancreatic tumor cells to induce danger signaling and enhance antigen presentation, thereby promoting immune infiltration and sensitizing tumors to PD-1 blockade.