PDCD1 and hepatocellular carcinoma: Our preclinical animal experiments including subcutaneous tumor models, orthotopic tumor models, and the DEN-induced HCC model, validated the synergistic effect of Prdm1 overexpression and PD-1 mAb treatment, in terms of a distinct reduction in tumor size/number and extended overall survival, which was attributed to the reinforcement of TILs in the tumors.