CTLA4 and neoplasm: Tumor cells mediate immunosuppression by hijacking inhibitory checkpoint proteins such as programmed death 1 (PD-1), T cell immunoglobulin and mucin domain 3 (TIM-3), lymphocyte activation gene 3 (LAG-3), and cytotoxic T lymphocyte antigen 4 (CTLA-4) expressed at the surface of T lymphocytes [4, 5].