As delegates trooped home from the American Society for Bone and Mineral Research meeting in Montreal, the potential for Amgen’s much-touted investigational osteoporosis treatment denosumab was on many people’s minds.

The biotechnology giant said in July that the 7,868-patient Phase III FREEDOM trial of denosumab, which is injected every six months, met its primary endpoint of reducing the incidence of new vertebral fractures compared to placebo. It was only in Montreal that the firm revealed by how much.

The data showed that the drug, a human monoclonal antibody that targets RANK ligand, an essential regulator of osteoclasts (the cells that break down bone), reduced vertebral fractures by 68%, a statisticallly significant figure and on a par with Novartis' Reclast (zoledronic acid), a bisphosphonate, which is given as a 15-minute infusion once a year. Furthermore, hip fracture risk reduction was 40% and 20% for other non-vertebral fractures.

Amgen also noted that infections classified as serious adverse events occurred in 4.1% of patients receiving denosumab and in 3.4% on placebo. Another study presented in Montreal, a non-pivotal Phase III head-to-head, double-blind trial called STAND, showed that postmenopausal women who transitioned from weekly oral alendronate (sold by Merck & Co as Fosamax and now available generically) to denosumab achieved significantly greater gains in bone mineral density versus those continuing on alendroate.

The company also presented the results from the DECIDE study which showed that more than three-quarters of patients in both denosumab and alendroanate arms preferred subcutaneous injection over pills (77% vs 23%). In addition, significantly more patients were more satisfied with twice-yearly dosing compared to weekly dosing.

Indeed it is the dosing issue that could help Amgen make its mark in the very crowded osteoporosis market where Fosamax and Reclast currently compete with Roche/GlaxoSmithKline’s Boniva/Bonviva (ibandronic acid) and Procter & Gamble/Sanofi-Aventis’ Actonel (risedronate), among others.

Steven Cummings of the University of California at San Francisco and lead investigator of the FREEDOM trial, told PharmaTimes World News that compliance is a main problem which denosumab addresses and the safety profile and ease of administration make it a valuable drug. Amgen is expected to file denosumab in all the major markets by the end of the year.

However one major problem facing the company will be cost. Amgen said it was too early to talk about pricing but its biologic will be obviously more expensive than generic alendronate.

Nevertheless, alendronate and most of the other bisphosphonates are very difficult to take and many patients discontinue their use within a year. Dr Cummings said that for the latter group of patients, denosumab is an attractive option.

He concluded by noting that from the perspective of primary care practice, denosumab also has an advantage over Reclast as setting up the infusion is awkward, requiring time and space. However with the Amgen drug, “it would be like getting a flu shot."