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ACTIVExtend: BMD response increases long term with abaloparatide followed by alendronate
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CHICAGO — Postmenopausal women with osteoporosis saw increased bone mineral density and reduced fracture risks over 43 months with alendronate follow-up to both abaloparatide therapy and placebo, but improvements were substantially greater with the abaloparatide-alendronate regimen, according to results of a prespecified responder analysis of ACTIVExtend data reported here.
“This study showed that the number of people who responded by having an increase in bone mineral density with the abaloparatide group vs. placebo was much higher. When the study was extended with the antiresorptive alendronate, the abaloparatide followed by alendronate group compared to the placebo followed by alendronate group also had a much greater response to BMD over time,” Lorraine A. Fitzpatrick, MD, chief medical officer at Radius Health, told Endocrine Today.
The phase 3 ACTIVExtend included participants from the initial ACTIVE phase 3 study who were assigned abaloparatide, a selective activator of the PTH1 receptor (Tymlos, Radius Health; n = 558), or placebo (n = 581) for 18 months followed by 24 months of alendronate after a 1-month reconsent period. Researchers analyzed data from those ACTIVE participants who were identified as responders to therapy — women who had achieved specified increases in BMD at all of three sites: increases greater than 0% at the lumbar spine, greater than 3% at the total hip and greater than 6% at the femoral neck. Researchers used Chi-square tests to compare the number of responders between the abaloparatide and placebo groups.
By the end of ACTIVExtend at month 43, 93.1% of the abaloparatide group exhibited BMD increases greater than 3% at the lumbar spine vs. 79.4% of the placebo group. BMD increases greater than 3% at the total hip were seen in 80.1% of the abaloparatide group vs. 52.1% of the placebo group. BMD increases greater than 3% at the femoral neck were seen in 67.5% of the abaloparatide group vs. 34.9% of the placebo group. In the abaloparatide group, 60.7% achieved BMD increases greater than 3% at all three sites and 33.5% of participants achieved increases greater than 6% vs. 24% and 4% of the placebo group, respectively (P < .0001 for all).
“Since the goal of osteoporosis treatment is to prevent fracture, using an anabolic agent first really will let you gain BMD and prevent fractures followed by an antiresorptive will consolidate or extend that effect and prevent further fractures and falling BMD. This study provides good guidance for clinicians as to how to maintain that fracture risk reduction,” Fitzpatrick said. – Jill Rollet
Reference:
Deal C, et al. OR03-4. Presented at: The Endocrine Society Annual Meeting; March 17-20, 2018; Chicago.
Disclosures: Fitzpatrick reports she is an employee of Radius Health. Please see the abstract for all other authors’ relevant financial disclosures.