A drug used to prevent or treat certain bone problems. Under the brand name Xgeva, it is used to prevent broken bones and other bone problems caused by solid tumors that have spread to bone. It is also used in certain patients to treat giant cell tumor of the bone that cannot be removed by surgery. Under the brand name Prolia, it is used to treat osteoporosis (a decrease in bone mass and density) in postmenopausal women who have a high risk of breaking bones. Denosumab is also being studied in the treatment of other conditions and types of cancer. It binds to a protein called RANKL, which keeps RANKL from binding to another protein called RANK on the surface of certain bone cells, including bone cancer cells. This may help keep bone from breaking down and cancer cells from growing. Denosumab is a type of monoclonal antibody. Also called AMG 162, Prolia, and Xgeva.