PDCD1 and hepatocellular carcinoma: Beyond melanoma, FDA approval of anti-PD-1 and anti-CTLA-4 dual therapy has expanded to hepatocellular carcinoma (HCC), unresectable pleural mesothelioma, RCC, metastatic non-small cell lung cancer (NSCLC), and advanced or metastatic esophageal squamous cell carcinoma (66–68).