Denosumab: a new treatment option for giant cell tumor of bone.

Giant cell tumor of bone (GCTB) is an osteolytic, usually benign neoplasm characterized by infiltration with osteoclast-like giant cells, and the osteoclast differentiation factor receptor activator of nuclear factor kappa-B ligand (RANKL) is heavily involved in its pathogenesis. Denosumab belongs to a new class of drugs that inhibit RANKL. Prior to denosumab, multimodality treatment in refractory, recurrent and metastatic GCTB has shown variable results. Recent phase II data have demonstrated denosumab's activity with regard to disease and symptom control, without significant adverse effects. On the basis of this data, the FDA approved denosumab for the treatment of patients whose GCTB is unresectable, or when surgery is likely to result in severe morbidity. Ongoing questions remain, including the optimal scheduling, patient selection, use in the adjuvant setting and long-term toxicity concerns.