To date, several distinct ICBs, including (1) the CTLA-4 antibody ipilimumab (Yervoy); (2) the PD-1 inhibitors: Cemiplimab (Libtayo), nivolumab (Opdivo), and pembrolizumab (Keytruda); and (3) the PD-L1 blockers: Atezolizumab (Tecentriq), avelumab (Bavencio), and durvalumab (Imfinzi), have been approved to treat a variety of advanced cancers, including melanoma, non-small cell lung cancer (NSCLC), hepatocellular carcinoma (HCC), head and neck squamous cell carcinoma (HNSCC), and urothelial carcinoma. This evidence concerns the gene CTLA4 and head and neck squamous cell carcinoma.