CTLA4 and neoplasm: Immune cells typically infiltrate the tumor microenvironment and have the ability to detect cancer-specific antigens; however, cancer cells often evolve the ability to hijack self-tolerance mechanisms, inhibiting the immune response and allowing them to evade destruction.1,2 These self-tolerance mechanisms are referred as immune checkpoints and involve inhibitory receptors such as CTLA4, PD1, TIM3, LAG3, and BTLA, which are expressed on immune cells.