Nivolumab and ipilimumab are types of immunotherapy. Immunotherapy works by encouraging the body's own immune system to attack cancer cells. Nivolumab has been approved by the US Food and Drug Administration (FDA) for the treatment of metastatic melanoma (a type of skin cancer), and specific types of previously treated advanced lung and kidney cancers. Ipilimumab is approved by the FDA for the treatment of metastatic melanoma.