Phase 1 Trial of Ipilimumab and GVAX in Patients With Metastatic Castration-resistant Prostate Cancer

A promising immunotherapeutic approach in prostate cancer is whole-cell vaccination. Irradiated allogeneic tumor cells expressing GM-CSF generate a long-lasting and specific anti-tumor immunity in preclinical models. Results from several phase I and II trials showed Prostate GVAX (GVAX) to be well tolerated and suggested improved survival. Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a crucial immune checkpoint molecule that down-regulates T-cell activation and proliferation. Ipilimumab, a fully human monoclonal antibody (IgG1) that blocks CTLA-4, promotes antitumor immunity, and has been demonstrated in two phase III trials to improve overall survival in metastatic melanoma patients. Pre-clinical studies of the anti-CTLA-4 antibody in combination with GM-CSF secreting tumor cell vaccines demonstrated a potent synergy. In this phase I study the investigators examine in CRPC patients whether ipilimumab can be safely combined with GVAX. In addition, the investigators will treat an additional 16 patients at a dose level of 3•0 mg/kg to determine the safety profile and antitumor effects of GVAX and ipilimumab in patients with CRPC.