CTLA4 and cancer: The sevaccine approaches to elicit strong specific immune responses to tumor antigens, approaches involving adoptive transfer of in vitro expanded, naturally arising, or genetically engineered tumor-specific lymphocytes, therapeutic administration of monoclonal antibodies to target and eliminate tumor cells, and approaches that inhibit or destroy the molecular or cellular mediators of cancer induced immunosuppression such as CTLA-4, PD-1, or Treg cells [7].