PDCD1 and hepatocellular carcinoma: Phase 1/2 studies have demonstrated the promising clinical efficacy of ICIs, such as programmed cell death protein 1 (PD-1), programmed death ligand 1 (PD-L1) and CTLA-4 inhibitors, as second-line treatments for HCC (18,20), including unresectable and advanced HCC (28–30); these ICIs have good response rates, and 12.9% (95%CI, 6.7–19.1%) patients achieve a pathological complete response (pCR) (31).