PDCD1 and hepatocellular carcinoma: Nivolumab was the first approved monoclonal antibody targeting PD-1 and can be administered in advanced melanoma, Hodgkin’s lymphoma, HCC, NSCLC and SCLC, RCC, head and neck cancer, urothelial carcinoma, CRC [5], gastric, or esophageal adenocarcinoma [16], and malignant pleural mesothelioma [13].