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Bone mineral density gains from Tymlos for osteoporosis maintained following alendronate
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Gains in ultradistal radius bone mineral density demonstrated by postmenopausal women with osteoporosis who had been treated with abaloparatide for 18 months were maintained throughout the following 24 months with open-label alendronate, according to a poster presented at the ASBMR 2018 Annual Meeting.
“This study is important as this is the first time that data has shown an increase in forearm bone density with an anabolic agent,” Robin K. Dore, MD, of the University of California, Los Angeles, told Healio Rheumatology. “Bone density studies are usually performed to monitor a response to treatment for osteoporosis. If a patient has bilateral hip replacements and osteoarthritis in the lumbar spine, the forearm is the only site that can be measured to accurately detect changes in response to osteoporosis therapy.”
She added, “Now we have data that abaloparatide increases bone density at this site, which makes it an accurate site to evaluate bone density response to abaloparatide when other sites cannot be measured.”
To determine the efficacy of abaloparatide (Tymlos, Radius Health) followed by alendronate, compared with placebo followed by the open-label treatment, on ultradistal-radius bone mineral density over 43 months, the researchers conducted a follow-up extension to the previous ACTIVE phase 3 trial.
In the ACTIVE study, researchers found that 18 months of abaloparatide therapy significantly increased bone mineral density at the ultradistal radius, as well as the 1/3 distal radius, compared with placebo and teriparatide. Participants treated with abaloparatide or placebo were offered enrollment in the ACTIVExtend extension study.
In the extension trial, 213 women who had initially been treated with abaloparatide, and 233 who received placebo, were all given open-label alendronate at 70 mg per week, for 24 months. That time, plus 1 month for enrollment and the previous 18 months of the ACTIVE phase 3 study, made for a total of 43 months of treatment. The researchers noted forearm bone mineral density data both at ACTIVE baseline and at 43 months. In addition, they centrally analyzed bone mineral density, adjusting for machine differences. Wrist fracture event rates were also estimated.
According to the researchers, the results of the initial ACTIVE phase 3 trial — ultradistal radius bone mineral density decreased among those in the placebo group, but increased in those treated with abaloparatide — were maintained in the extension. Among those in the abaloparatide group who entered the extension, 15 experienced wrist fractures, compared with 20 who had been in the placebo group. Although the number of fractures was low, such events were numerically lower among those treated with abaloparatide compared to placebo (HR = 0.77; 95% CI, 0.39-1.5).
“This data emphasizes the beneficial effect that abaloparatide has throughout the entire skeleton,” Dore said. “Thus, prescribers should be very confident in using this anabolic agent to treat their post-menopausal women with osteoporosis at high risk for fracture.” – by Jason Laday
Reference: Watts B. Abstract SUN-0941. Presented at: ASBMR 2018 Annual Meeting; Sept. 28 to Oct. 1; Montreal.
Disclosure: Dore reports professional relationships with Radius Health, Eli Lilly and Amgen. Please see the study for all other authors’ relevant financial disclosures.