CTLA4 and neoplasm: In particular, anti-CTLA-4 antibodies of the IgG2a isotype seemed to be capable of engaging Fcγ receptors expressed by tumor-associated macrophages within the tumor microenvironment in mouse models, hence to mediate an antitumor activity via selective elimination of intratumoral T cell populations, particularly Tregs (Bulliard et al., 2013; Simpson et al., 2013).