The U.S. Food and Drug Administration (FDA) has approved a new indication for denosumab (Xgeva) for the treatment of giant cell tumor of bone (GCTB), a rare and usually benign tumor, in adults and some adolescents. GCTB typically occurs in adult patients between the ages of 20 and 40. In most cases, GCTB does not spread to other parts of the body, but it can impair normal bone growth, causing pain, limited range of motion and fractures. In rare cases, giant cell tumor of bone can turn into a malignant tumor and spread to the lungs. Denosumab is a monoclonal antibody that binds to RANKL, an essential protein for healthy bones, which is also found in giant cell tumors of bone. Denosumab is used in patients with giant cell tumors of bone that cannot be removed surgically (cannot be removed) or where surgery may result in serious conditions such as amputation or joint removal. This drug should only be used in adolescent patients whose bones have matured. Richard?Pazdur, M.D., director of the Division of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said, “Today’s approval of a new indication for denosumab provides a needed treatment option for patients with giant cell tumors of the bone who cannot undergo surgery or whose surgery would result in serious medical conditions.” The FDA reviewed the drug through its priority review process, which provides an expedited review of a drug. Denosemide was granted orphan drug product status for its use in the treatment of a rare disease or condition. The safety and efficacy of Denosemide in giant cell tumor of bone was based on two clinical trials involving a total of 305 adult or adolescent patients. All patients were diagnosed with recurrent, unresectable, or surgical cases of giant cell tumor of the bone that would result in severe disease symptoms. After an average of three months of dosing, 47 of the 187 patients whose tumors could be measured showed shrinkage. After an average follow-up of more than 20 months, three patients whose tumors had gotten smaller during the initial treatment had their giant cell tumors of bone grow back. Common side effects of Denosumab include arthralgia, headache, nausea, fatigue, and back and hand and foot pain. The most common serious side effects are osteonecrosis of the jaw and osteomyelitis (inflammation or bone infection). Because of the potential harm to the fetus, it is important that women of childbearing age use highly effective birth control when using this drug.