At present, since pembrolizumab and nivolumab, anti-PD-1 humanized antibodies, have shown encouraging signs of efficacy in relapsed and refractory HCC patients who previously received sorafenib in several trials, these two drugs were approved by the US Food and Drug Administration (FDA) as a second-line treatment for these patients (8, 9). Here, PDCD1 is linked to hepatocellular carcinoma.