Twice-yearly injections with Amgen’s antibody drug denosumab increase bone mineral density in women with post-menopausal osteoporosis, according to a Phase II trial reported in today’s edition of the New England Journal of Medicine.
The trial showed that denosumab – one of the hottest prospects in Amgen’s pipeline – significantly increased bone mineral density compared to placebo. It also seemed to perform better than a widely-used treatment for osteoporosis, Merck & Co’s Fosamax (alendronate), although no head-to-head comparison of the two drugs was undertaken.
The results showed that subcutaneous injections of denosumab increased bone mineral density in the hip between 1.9% and 3.6% in women who were administered the therapy for a year, compared with a decrease of 0.6% in the placebo group. An open-label Fosamax group receiving 70mg of the drug weekly had an increase of 2.1% over the same time frame.
In November, Amgen reported preliminary from the same study which showed that after two years, the increase in bone mineral density ranged from 4.3% to 9%. This efficacy is comparable to that seen with Fosamax and other drugs in the bisphosphonate class, but Amgen is hoping its drug will be better tolerated by patients.
Studies suggest that despite the effectiveness of bisphosphonates, less than half of patients continue on treatment long-term because of side effects, particularly irritation of the upper gastrointestinal tract, as well as complex dosing instructions such as a requirement to sit upright for 30 to 60 minutes after dosing.
Denosumab (previously referred to as AMG 162), is the lead drug candidate in a new class of osteoporosis drugs, known as RANK Ligand inhibitors, that target a key cellular for bone removal. It was one of two antibodies partnered by Amgen and Abgenix, a US biotech it bought for $2.2 billion last December.
The drug is already in Phase III testing to counter bone loss caused by hormone therapy for breast and prostate cancer, as well as Phase II studies for the treatment of bone metastases.