CTLA4 and cancer: Several other immunotherapies for advanced PC have progressed to phase II or phase III clinical trials : the GVAX-PCa (GM-CSF immunotherapy for cancer; Biosante Inc) cell-based cancer vaccine [4, 5], or the Ipilimumab (Yervoy, BMS Princeton, NJ), fully human anti-Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) monoclonal antibody, alone or in combination with radiotherapy [6, 7].