THOUSAND OAKS, Calif., July 15, 2013 /PRNewswire/ -- Amgen (NASDAQ:AMGN) today announced the Lancet Oncology published planned interim results from an international, open-label, Phase 2 clinical trial that is evaluating XGEVA ® (denosumab) in adults and skeletally mature adolescents diagnosed with giant cell tumor of bone (GCTB). The study's primary endpoint is the safety profile of XGEVA. Secondary endpoints are the time to disease progression and the proportion of patients without any surgery at six months. Based on the investigators' interim assessment, 96 percent (163/169) of patients with surgically unsalvageable GCTB had no disease progression after a median follow-up of 13 months. In those with salvageable GCTB whose surgery was associated with severe morbidity, 74 percent (74/100) of patients required no surgery, and 62 percent (16/26) of patients who had surgery underwent a less morbid procedure than planned. Overall, 72 percent of patients had objective tumor response, per protocol defined criteria, including 25 percent of patients who had an objective tumor response according to modified RECIST(Response Evaluation Criteria In Solid Tumors). The overall safety profile was found to be consistent with the known safety profile of XGEVA in patients with advanced cancer. Osteonecrosis of the jaw was reported in one percent (3/281) of patients. Hypocalcemia adverse events, all non-serious, were reported in five percent (15/281) of patients. The most common severe adverse events were low phosphate levels, back pain, pain in extremity, depression, musculoskeletal pain and anemia. Serious adverse events were reported in nine percent (25/281) of patients. No treatment-related deaths were reported. "These results demonstrate the effectiveness of XGEVA in the treatment of giant cell tumor of bone and reinforce our understanding of this rare disease in which RANK Ligand plays a central role," said Sean E. Harper, M.D., executive vice president of Research and Development at Amgen. "XGEVA represents a much needed treatment option for patients who suffer from giant cell tumor of bone that can't be adequately treated with surgery." GCTB is a rare, osteolytic tumor of the bone that often results in complete destruction of the affected bone, leading to bone fracture, joint dysfunction, deformity or amputation. GCTB typically affects individuals between the ages of 20 to 40.