CTLA4 and cancer: These utilize several different mechanisms, some of which include: targeting the immune system, e.g., alemtuzumab (Campath®, Sanofi, France), which binds CD52 inducing an immune response; targeting antigens on cancer cells that are involved in cell growth and proliferation, e.g., trastuzumab (Herceptin®, Genentech, USA) for HER2; and immune check-point inhibitors, e.g., ipilimumab (Yervoy®, Bristol-Myers Squibb, USA) for cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4).