Adding Teriparatide Raises Hip BMD More Than Switching Drugs

Nancy A. Melville

October 24, 2012

MINNEAPOLIS, Minnesota — Postmenopausal women receiving ongoing antiresorptive osteoporosis therapy did better when teriparatide was added to their regimen than when they were switched to teriparatide monotherapy, researchers reported here at the American Society for Bone and Mineral Research 2012 Annual Meeting.

Felicia Cosman, MD, from Helen Hayes Hospital in West Haverstraw, New York, and colleagues used quantitative computed tomography (QCT) to determine whether the strength of the spine and hip increase more by adding or switching to teriparatide. "Specifically, we sought to determine whether the volumetric bone mineral density [vBMD] and estimated strength of the spine and hip increased from baseline in each group, and to compare vBMD and estimated strength changes between the groups," Dr. Cosman said.

Postmenopausal women with osteoporosis who had been treated for at least 18 months with alendronate 70 mg/week (n = 102) or raloxifene 60 mg/day (n = 106) were randomized to either add subcutaneous injections of teriparatide 20 µg/day to their current therapy or to switch to teriparatide 20 µg/day monotherapy.

QTC scans were taken at baseline, 6 months, and 18 months. Dr. Cosman and colleagues saw improvements in the 3 groups in spine strength and vBMD. There were no significant differences between women who added teriparatide to their ongoing therapy and those who switched to teriparatide monotherapy.

However, hip assessments told a different story. For alendronate plus teriparatide, hip vBMD increased significantly, compared with monotherapy, at 6 months (0.9% vs –0.5%; = .004) and at 18 months (2.2% vs 0.0%; = .002). At 18 months, hip strength increased significantly from baseline (2.7%; < .001).

For raloxifene plus teriparatide, hip vBMD and hip strength increased significantly at 6 and 18 months. For monotherapy, improvement was seen only at 18 months, not at 6 months.

"Adding or switching to teriparatide conferred similar benefits in spine strength in women with osteoporosis who were previously treated with raloxifene or alendronate," Dr. Cosman said.

"But for women at particularly high risk for hip fracture, adding teriparatide to ongoing bisphosphonate therapy should be considered a therapeutic option. Our data indicate it will increase volumetric BMD of the hip and improve hip strength," she noted.

Bart L. Clarke, MD, from the division of endocrinology and metabolism at the Mayo Clinic in Rochester, Minnesota, agrees that the findings suggest an approach that could have valuable clinical implications. However, "the findings are somewhat surprising. I don't think people expected to see better results with combination therapy," he noted.

"Teriparatide by itself is a very potent agent, and alendronate and raloxifene are moderately potent, but the combination of the 2, at least based on previous studies, actually showed a blunting of the effect of the teriparatide. The surprise in this case was that adding to the drug produced a better response than switching," he said.

"The data are important. For women who have not responded well to alendronate or raloxifene, adding teriparatide is an option," he explained.

"Obviously, there are issues with cost, interactions between the drugs, and side effects, but they didn't seem to be anything of significant concern" in this trial, he added.

Dr. Cosman reports receiving research grants or consulting fees from Lilly, Novartis, Amgen, and Merck; and being on the speaker's bureau for Lilly, Amgen, and Novartis. Dr. Clarke has disclosed no relevant financial relationships.

American Society for Bone and Mineral Research (ASBMR) 2012 Annual Meeting: Abstract 1100. Presented October 14, 2012.