PDCD1 and neoplasm: Taken together, these data indicated that ZD55-IL-24 rather than PD-1 blockade was able to improve tumor immune recognition in both local and distant tumors as well as spleens, and ZD55-IL-24 could help PD-1 blockade to overcome the limitation of relatively low tumor immune recognition, contributing to the observed synergistic effect in B16-bearing immunocompetent mouse model.