Cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death 1 (PD1) receptor inhibit antitumour immunity through complementary and non-redundant mechanisms. A new trial assessed the combination of ipilimumab (a CTLA4-specific monoclonal antibody) and nivolumab (a PD1-specific monoclonal antibody) in 142 patients with metastatic melanoma