CTLA4 and cancer: Several immunotherapies are currently in clinical trial including a few immunotherapy combination treatments such as viral vaccines targeting different cancer antigens (PSA, CEA, and MUC1), viral vaccines with anti-CTLA4 and anti-PD-1, Sipuleucel-T with anti-CTLA4, anti-PD-L1 with interleukin-15 (IL-15) superagonist, IDO inhibitor, and viral vaccines, and other combinations with GM-CSF (Additional file 1).