PDCD1 and hepatocellular carcinoma: According to the previous studies, pembrolizumab and nivolumab might prolong the PFS of advanced HCC patients to 5.5 months (95% CI 3.5–7.4) and 4.6 months (95% CI 3.0–6.2) respectively31, indicating a promising effectiveness of PD-1 inhibitors on improving HCC patient survival.