You don't hear about giant-cell tumor of bone (GCTB) every day, but here's some good news for the people who suffer from the destructive bone disease: The FDA has approved a new indication for Amgen's Xgeva® (denosumab) for the treatment of adults and skeletally mature adolescents with GCTB that is unresectable or where surgical resection is likely to result in severe morbidity. Xgeva was approved for this indication following a priority review by the FDA, a designation reserved for drugs that offer major advances in treatment, or provide a treatment where no adequate therapy exists.
Xgeva works by binding RANK Ligand (RANKL), a protein essential for the formation, function, and survival of osteoclasts, the cells responsible for bone resorption. Giant-cell tumors of bone consist of stromal cells expressing RANKL and osteoclast-like giant cells expressing RANK receptor. Signaling through the RANK receptor contributes to osteolysis and tumor growth. Xgeva prevents RANKL from activating its receptor, RANK, on the surface of osteoclasts, their precursors and osteoclast-like giant cells.
Xgeva was approved after positive results from two open-label trials that enrolled patients with GCTB that was either recurrent, unresectable, or for which planned surgery was likely to result in severe morbidity. A total of 304 patients received denosumab; radiographic assessments at baseline and following denosumab treatment were available for 187 (61%) patients. The overall objective response rate of the 187 patients evaluated was 25%. In the 47 patients with an objective response, 51% (24) had a duration of response lasting at least eight months.
"With today's Xgeva FDA approval, Amgen can offer a much-needed treatment option to patients who suffer from giant-cell tumor of bone that cannot be adequately treated with surgery," said Sean E. Harper, M.D., evp, R&D at Amgen. "Advances in our understanding of the underlying biology of this rare disorder have allowed Amgen to generate compelling clinical evidence to address the medical needs of patients and their healthcare providers."
That's not the only good news Amgen has been getting: Just Wednesday, it announced that its trebananib had met its primary endpoint in a trial for recurrent ovarian cancer. Earlier this month, the company also announced that its oncolytic immunotherapy talimogene laherparepvec, in a Phase III trial evaluating it in patients with unresected stage IIIB, IIIC, or IV melanoma compared to granulocyte-macrophage colony-stimulating factor (GM-CSF), also met its primary endpoint.