Ipilimumab injection is used alone or in combination with nivolumab (Opdivo) to treat certain types of melanoma (a type of skin cancer) that that has spread to other parts of the body or cannot be treated with surgery. It is also used alone to prevent melanoma from returning after surgery. Ipilimumab injection is also used in combination with nivolumab to treat certain types of renal cell cancer (a type of cancer that begins in the cells of the kidneys), colorectal cancer (cancer that begins in the large intestine), hepatocellular cancer (a type of liver cancer), esophageal cancer (cancer of the tube that connects your throat to your stomach), and malignant pleural mesothelioma (a type of cancer that affects the inside lining of the lungs and chest cavity). It is also used in combination with nivolumab and other chemotherapy medications to treat a certain type of lung cancer (non-small cell lung cancer, NSCLC). Ipilimumab injection is in a class of medications called monoclonal antibodies. It works by helping the body to slow or stop the growth of cancer cells.