Amgen received FDA approval for a higher dose of its denosumab injection, Xgeva, which puts the drug in competition with Novartis’ Zometa (zoledronic acid) for the prevention of bone damage in patients with certain types of cancer. A lower dose of denosumab, Prolia, was approved by FDA in June for osteoporosis.

With a new indication and brand launch for denosumab, Amgen hopes to siphon market share away from Zometa, which had sales exceeding $1 billion for the first nine months of 2010. Zometa, however, is approved for the prevention of skeletal-related events (SREs) in patients with solid tumors and multiple myeloma, while Xgeva is approved only in patients with solid tumors, such as breast, lung and prostate cancers.

Christine Regan, a spokesperson for Amgen, said the company is “planning to conduct a phase 3 study to evaluate the effects of Xgeva compared with Zometa in patients with multiple myeloma,” adding that the study will be designed similarly to trials that tested Xgeva versus Zometa in patients with solid tumors, but will include myeloma-specific disease endpoints.

Sales reps supporting Xgeva will target oncologists and urologists, said Regan. She declined to comment on the size or structure of the sales force. The company announced an Xgeva “First Step” coupon program that offers patients a free inaugural injection and a maximum out-of-pocket expense of $25 for subsequent injections. Without insurance, Xgeva will cost $1,650 monthly based on wholesale acquisition cost, according to a company estimate. Zometa costs around $844 per dose, which is given every three to four weeks, according to a Wall Street Journal report.

“Our clinical data demonstrate that Xgeva is superior to Zometa in a pre-specified integrated analysis in the treatment of skeletal complications in patients with bone metastases,” said Regan in an email. “This clinical profile combined with other features, such as no dose adjustments for renal function and subcutaneous dosing, present a compelling new treatment option for patients with bone metastases.”