CTLA4 and neoplasm: Immune checkpoints, such as programmed cell death 1 (PD-1), cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and lymphocyte activation gene 3 (LAG-3), are important mechanisms for preventing the immune system overactivation (Zang, 2018), the overexpression of these immune checkpoints establish an immunosuppressive state called tolerance toward body cells, which is the root cause of the immune system's inability to clear tumor cells.