Amgen is celebrating the news that regulators in the USA have given a second green light to the biotech's key compound denosumab.

The US Food and Drug Administration has approved Xgeva (denosumab) for the prevention of skeletal-related events in patients with bone metastases from solid tumors. The thumbs-up follows a six-month priority review by the agency of data from three Phase III head-to-head trials that evaluated the subcutaneous injection drug versus Novartis' intravenous infusion Zometa (zoledronic acid).

In those studies, Xgeva demonstrated a clinically meaningful improvement in preventing SREs compared to Zometa, and in particular in patients with breast or prostate cancer and bone metastases, the Amgen drug was superior. In patients with bone metastasis due to other solid tumors or bone lesions due to multiple myeloma, Xgeva was noninferior (though "trending towards superiority") to Zometa in reducing the risk of SREs, although the FDA has not backed approval for the prevention of SREs in patients with MM.

Amgen quoted David Henry of the Pennsylvania Hospital as saying that "as many as three out of four patients with advanced prostate, lung and breast cancer will experience spread to their bones. Despite the availability of current treatments, a significant proportion of these patients still experience bone complications or are not candidates for existing treatment". He added that "based on the compelling science and robust clinical evidence seen with Xgeva, I expect this new option to quickly become a mainstay of cancer care".

Denosumab, under the brandname Prolia, was approved by the FDA in May for postmenopausal women with osteoporosis who are at high risk for fractures. It has been widely touted as a blockbuster but the drug only brought in $10 million in third-quarter sales, well below analyst forecasts.

This latest approval will boost that figure though there are concerns about the take-up Xgeva will have, given its high price. Amgen says the drug will cost $1,650 monthly, but has set up a programme for uninsured patients who will incur no out-of-pocket costs for their initial Xgeva injection and pay a maximum of $25 for subsequent injections". The company added that the total economic burden of patients with bone metastases in the USA alone is estimated to be $12.6 billion annually.