A drug used to treat classical Hodgkin lymphoma that has gotten worse after treatment with an autologous stem cell transplant and brentuximab vedotin (a type of anticancer drug). It is also used alone or with other drugs 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. Opdivo binds to a protein called PD-1, which is found on T cells (a type of white blood cell). Opdivo 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 nivolumab.