CTLA4 and neoplasm: Immunosuppressive cells within the tumor microenvironment disrupt T cell activation and proliferation by increasing the expression of immunosuppressive receptors such as PD-1 and CTLA-4 and by releasing immunosuppressive cytokines like IL-6, IL-10, TGFβ, and VEGF (Mariathasan et al., 2018; Mazzarella et al., 2019).