At the moment, immune checkpoint inhibitors, monoclonal antibodies binding to immune response inhibiting receptors (programmed death-1 (PD-1), PD ligand-1 (PD-L1), or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)) [18], are the most developed, investigated, and approved to treat various cancer types. The gene discussed is CTLA4; the disease is cancer.