PDCD1 and neoplasm: In addition, the distant tumor volumes in the VNP-GD/EI-NP@Gel+aPD-1 group were significantly smaller than that in the VNP-GD/EI-NP@Gel group, demonstrating the synergistic efficacy when combined with aPD-1 antibodies to block PD-1/PD-L1 pathway to re-activate T cells for antitumor immunity (Fig. 4k).