Blockade of PD-1/PD-L1 immune checkpoint during DC vaccination induces potent protective immunity against breast cancer in hu-SCID mice

• Blockade of PD-1/PD-L1 promotes DC maturation and proliferation.
• Blockade of PD-1/PD-L1 between DC-T cell interaction reverses T cell impairment.
• Blockade of PD-1/PD-L1 between tumor-T cells interaction enhances T cell function.
• Blockade of PD-1/PD-L1 during whole process of DC vaccination enhances antitumor efficiency.

Immune checkpoints, such as the PD-1/PD-L1 pathway, negatively interfere in the efficiency of dendritic cell (DC) vaccination in cancer immunotherapy. In this study, we demonstrated that the blockade of PD-L1 signaling could promote DC maturation, proliferation, and IL-12 secretion, augment DC primed T cell response and reverse tumor cell dampened T cell impairment. Blockade of PD-L1 signaling during DC vaccination showed better therapeutic effects than classic DC vaccination by preventing tumor growth and prolonging survival times in a breast tumor-bearing hu-SCID model. Taken together, suppressing immune checkpoints during DC vaccination might be a more efficient strategy for cancer therapy.