CTLA4 and neoplasm: Furthermore, there is evidence that the tumor cells can escape immune surveillance by upregulating immune-suppressive molecules including lymphocyte-activation gene (LAG-3) and CTLA-4 as well as by the absence or decreased infiltration of (CD-8 positive) tumor-infiltrating leukocytes or the increased presence of immunosuppressive cells, such as regulatory T cells and myeloid-derived suppressor cells, in the tumor microenvironment [33,34].