Adding combination immunotherapy consisting of cancer vaccine, anti-PD-1 and anti-CSF1R antibodies to gemcitabine improves anti-tumor efficacy in murine model of pancreatic ductal adenocarcinoma

Immunotherapy can take advantage of the immunogenic response that chemotherapy elicits in tumors. Gemcitabine is a standard agent used in the treatment of pancreatic cancer, with known effects on the tumor immune microenvironment. The combination immunotherapy of the GVAX cancer vaccine, anti-PD-1 antibody and anti-CSF-1R antibody has been shown to improve survival in a murine model of metastatic pancreatic adenocarcinoma. This combination regimen also increased the infiltration of CD8+ T-cells that expressed both PD1 and CD137, and these T-cells were shown to express high levels of interferon-gamma, a marker of cytotoxic effector CD8+ T-cells. The effect of the addition of gemcitabine to this promising immunotherapy regimen has not been investigated.