PDCD1 and hepatocellular carcinoma: On the basis of the results of the Checkmate040 and KEYNOTE224 trials, two programmed cell death protein 1 (PD-1) inhibitors—nivolumab and pembrolizumab—were approved by the United States Food and Drug Administration (FDA) for second-line therapy of HCC (El-Khoueiry et al., 2017; Zhu et al., 2018).