PDCD1 and hepatocellular carcinoma: Inhibitors of CTLA-4 and PD-1/PD-L1 have shown success in various cancers, such as melanoma, non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma (HNSSC), urothelial carcinoma, colorectal cancer, cervical cancer, endometrial carcinoma, triple-negative breast cancer (TNBC), renal cell carcinoma (RCC), hepatocellular carcinoma (HCC), or Hodgkin lymphoma (HL), producing promising results [3,4].