Antibodies (Abs) against CTLA-4 (Ipilimumab), PD-1 (Pembrolizumab, Nivolumab, and Cemiplimab), and PD-L1 (Durvalumab, Atezolizumab, and Avelumab) have been approved by the Food and Drug Administration (FDA) to treat patients with advanced melanoma, lymphoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), bladder cancer, head and neck squamous cell cancer (HNSCC), liver cancer, and Merkel cell carcinoma. Here, PDCD1 is linked to liver cancer.