PDCD1 and hepatocellular carcinoma: Immune checkpoint blockade immunotherapy based on programmed cell death protein 1 (PD-1) has gained widespread attention for HCC treatment.[125] Several studies have shown that combination therapies based on quercetin or PD-1 inhibitors can effectively limit HCC progression.[126,127] Wu et al[119] suggested that the use of PD-1 blockers to modulate tumor-associated macrophages within the TME, remove T-cell inhibitory signals, and restore the antitumor immune response within the TME provides a promising approach for HCC treatment.