Vaccines Combined with Immune Checkpoint Antibodies Promote Cytotoxic T-cell Activity and Tumor Eradication

Despite dramatic clinical successes for cancer vaccines and immune checkpoint blockade, disease usually progresses. In a mouse model that combined vaccines with checkpoint blockade, significant CTL activation, tumor eradication, and long-term survival was achieved. We demonstrate that a poly(lactide-co-glycolide) (PLG) cancer vaccine can be used in combination with immune checkpoint antibodies, anti–CTLA-4 or anti–PD-1, to enhance cytotoxic T-cell (CTL) activity and induce the regression of solid B16 tumors in mice. Combination therapy obviated the need for vaccine boosting and significantly skewed intratumoral reactions toward CTL activity, resulting in the regression of B16 tumors up to 50 mm2 in size and 75% survival rates. These data suggest that combining material-based cancer vaccines with checkpoint antibodies has the potential to mediate tumor regression in humans. Cancer Immunol Res; 4(2); 95–100. ©2015 AACR.

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