This research is being done to test the effectiveness (how well the drug works), safety, and tolerability of an investigational drug called nivolumab (also known as BMS-936558). Nivolumab is an antibody (a type of human protein) that is being tested to see if it will allow the body’s immune system to work against tumor cells. Some patients may receive one dose of a second investigational drug called ipilimumab which is also being tested to see if it improves the immune response. The use of nivolumab and ipilimumab in this study is investigational. Another purpose of this study is to test how well we can detect the expression of a biomarker (a substance in the blood) known as PD-L1 and other markers that may predict who will respond best to immunotherapy.