The US FDA yesterday gave a green to the use of Amgen’s Xgeva (denosumab) to treat adults and some adolescents with giant cell tumour of the bone (GCTB).
The rare and usually non-cancerous tumour is generally found in adults between the ages of 20 and 40 and, while it does not generally spread to other parts of the body, it does cause localised problems including pain and bone fractures. In rare cases the tumour can spread to the lungs.
At the moment the only available treatments for GCTB are radiotherapy and surgery, although the latter is not an option for all patients and in some cases can require dramatic reconstructive therapy.
GTCB only occurs in around one in a million people, but Amgen was able to carry out two clinical trials involving a total of 305 patients with GCTB that had recurred after prior surgery – which happens in around 45 per cent of cases – or were unsuitable for surgery.
Of the 187 patients whose tumours could be measured, 47 patients showed a reduction in tumour size after an average of three months, said the FDA. Over an average follow-up duration of 20 months, re-growth of GCTB occurred in three patients whose tumours originally became smaller during treatment.
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,” said the FDA’s Richard Pazdur, who heads the Office of Hematology and Oncology Products at the agency’s Center for Drug Evaluation and Research (CDER).
The drug has been on the market in the US since 2010 as a treatment for skeletal-related events in patients with bone metastases from solid tumours, but an attempt by Amgen to expand its use into the prevention of bone metastases in prostate cancer was turned down by the FDA last year.
While GCTB is a minor market for the drug, Xgeva is a major growth platform at Amgen bringing in $748m last year at a time when the biotech company is suffering from declining sales of its red blood cell stimulators Epogen (epoetin alfa) and Aranesp (darbepoetin alfa).
Another formulation of denosumab – called Prolia – added another $472m from its use in osteoporosis in 2012.