Pembrolizumab, a monoclonal antibody blocking PD-1 (Figs. 3 and 4), has demonstrated potent anti-tumor activity and tolerable safety across many cancers [48], and its efficacy and safety were evaluated in advanced HCC patients via a nonrandomized, multicenter phase II trial (KEYNOTE-224; NCT02702414). The gene discussed is PDCD1; the disease is hepatocellular carcinoma.