FDA approves Xgeva to treat giant cell tumor of the bone
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The FDA recently expanded the approved indications for the monoclonal antibody denosumab to include treatment of adults and some adolescents with giant cell tumor of the bone.
Giant cell tumor of the bone (GCTB), a rare and often noncancerous tumor, typically occurs in individuals aged 20 to 40 years. It destroys normal bone as it grows, causing fractures and pain, and limiting patients’ range of motion. In a small percentage of cases, it can transform into a cancerous tumor and metastasize to the lungs.
Denosumab (Xgeva, Amgen) — approved in 2010 to prevent fractures in patients whose noncancerous tumors spread to their bones — binds to the RANKL protein, which is necessary for the maintenance of healthy bone. It is intended for patients whose tumors are unresectable, or for those who likely would suffer severe morbidity — including joint removal or loss of limbs — if they underwent surgery.
The approval, granted under the FDA’s priority review program, only extends to adolescent patients whose bones have matured.
Richard Pazdur
“[The] approval of Xgeva provides a needed treatment option for patients with GCTB who are not surgical candidates or who would otherwise have to undergo extensive, life-altering surgery,” Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said in a press release.
The FDA based its approval on the results of two clinical trials that included 305 patients with recurrent or unresectable GCTB, or for whom surgery would cause severe morbidity.
Forty-seven of the 187 patients (25.1%) whose tumors could be measured experienced reduction in tumor size after an average of 3 months, according to the FDA. During an average 20-month follow-up, three of those patients exhibited GCTB regrowth.
The most common serious side effects reported by patients treated with denosumab included osteonecrosis of the jaw, as well as inflammation or infection of the bone. Other common side effects included joint pain, nausea, headache, back pain, fatigue and extremity pain.