PDCD1 and hepatocellular carcinoma: So far, the Food and Drug Administration (FDA) of America has approved several ICIs targeting PD-1/PD-L1 for the treatment of various malignancies, among which promising results have been observed in the treatment of non-small cell lung cancer (NSCLC), melanoma, renal cell cancer (RCC) and hepatocellular carcinoma (HCC), with the response rate ranged from 50%-90% 17,18,19,20.