In preclinical studies, the blockade of CTLA4 led to a 1.5- to two-fold increase in the proliferation of T cells, a six-fold increase in the production of interleukin-2 [9,10] and the depletion of T regulatory lymphocytes in the tumor microenvironment through a macrophage-dependent process [10,11]. This evidence concerns the gene CTLA4 and neoplasm.