Additional Study Information: The purpose of this study is to test any good and bad effects of the study drugs called nivolumab and ipilimumab. Nivolumab alone or with ipilimumab could shrink your cancer but it could also cause side effects. Researchers hope to learn if the study drug will shrink the cancer by at least one-quarter compared to its present size, and to learn more about the side effects and science of the treatment. Both of the drugs work through your bodys immune system to help the immune system act against cancer cells. Ipilimumab has been studied and is FDA-approved to treat melanoma, a type of skin cancer. Nivolumab has been studied, and found to shrink tumors in some people with cancer. Nivolumab and ipilimumab have been studied given together. Nivolumab and Ipilimumab are considered experimental and are not FDA approved to treat sarcoma. Neither drug has been tested in all types of sarcoma, but has shrunk several types of sarcoma tumors in animals.