Pembrolizumab (Keytruda; prescribing information at https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/125514s015lbl.pdf), another anti-PD-1 monoclonal antibody, was used in a phase 2 trial (KEYNOTE-224) involving advanced-HCC patients who had previously been treated with sorafenib. Here, PDCD1 is linked to hepatocellular carcinoma.