CTLA4 and malignant colon neoplasm: In the colon cancer models CT-26 and MC38, anti-CTLA-4 mIgG2a antibody with enhanced Fc effector functions promoted enhanced anti-tumor activity through the reduction of intratumoral Tregs, as compared to tumor-bearing animals treated with anti-CTLA-4 antibodies of different isotypes with weaker effector functions, such as mIgG2b or mIgG1, or anti-CTLA-4 antibody lacking Fc effector functions (IgG1-D265A) [11].