Immune checkpoint inhibitors (ICIs), such as those targeting Programmed death ligand-1 (PD-1), Programmed death ligand (PD-L1), and Cytotoxic T lymphocyte-associated protein 4 (CTLA–4), have been approved for the treatment of various cancer types, including melanoma, lung cancer, and HNSCC (7–11). Here, CTLA4 is linked to cancer.