A drug used in certain patients to treat squamous cell cancer of the head and neck and classical Hodgkin lymphoma. Nivolumab is also used to treat certain types of melanoma, non-small cell lung cancer, and renal cell carcinoma (a type of kidney cancer). It is also being studied in the treatment of other types of cancer. Nivolumab binds to a protein called PD-1, which is found on T cells (a type of white blood cell). Nivolumab may block PD-1 and help the immune system kill cancer cells. It is a type of monoclonal antibody and a type of immune checkpoint inhibitor. Also called Opdivo.