In most patients who complete 1 year of denosumab therapy, treatment with alendronate can maintain the bone mineral density (BMD) gains. However, patients with greater BMD improvement after 1 year of denosumab are more likely to lose BMD after the transition to alendronate therapy in the second year, according to study results presented at the American Society for Bone and Mineral Research 2019 Annual Meeting, held September 20 to 23 in Orlando, Florida.
Analysis of data from the Denosumab Adherence Preference Satisfaction (DAPS) study indicated that alendronate therapy could maintain the gains in BMD achieved after 1 year of denosumab therapy. The goal of the current study was to explore the association between patient characteristics and their BMD response after switching from 1 year of denosumab therapy to alendronate therapy for an additional year.
DAPS was a 24-month open-label randomized crossover study that included postmenopausal treatment-naive women with a T-score ≤-2.0 to ≥-4.0 at the lumbar spine, total hip, or femoral neck. The participants were randomly assigned to denosumab (60 mg once every 6 months) or alendronate (70 mg once weekly). Measurement of BMD was completed at baseline, as well as after 1 and 2 years of therapy.
In the current analysis, the researchers focused on patients who were switched to alendronate therapy after 12 months of denosumab treatment. The patients were classified according to the changes in BMD from year 1 to year 2: loss (BMD least significant change ≤-3%), maintained (BMD least significant change >-3% and <3%), or gain (BMD least significant change ≥3%).
The cohort included 115 of 126 patients (mean age, 65 years; mean BMD T-scores of -2.0 at the lumbar spine, -1.6 at the total hip, and -2.0 at the femoral neck) who switched to alendronate therapy after receiving denosumab.
One year of denosumab therapy was associated with a BMD increase in all sites (5.6% at the lumbar spine, 3.2% at the total hip, and 3.1% at the femoral neck). After an additional 1 year of alendronate therapy, BMD changed by 0.6%, 0.4%, and -0.1%, respectively.
In most individuals who switched from denosumab to alendronate, BMD was stable or increased. Loss of BMD at the lumbar spine, total hip, and femoral neck was evident in 15.9%, 7.6%, and 21.7% of patients, respectively. Only 1 patient had evidence of BMD loss at all 3 sites.
The researchers reported that baseline characteristics, BMD at end of 1 year of denosumab therapy, and adherence to alendronate therapy did not predict the changes in BMD after 1 year of alendronate therapy. However, BMD loss after 1 year of alendronate therapy was more common in those who had greater gains in BMD from baseline to 1 year of denosumab therapy. Few patients with evidence of BMD loss fell below their prestudy baseline BMD value.
“These data highlight the need for oral [bisphosphonate] therapy following [denosumab] cessation and BMD monitoring of patients transitioning from [denosumab] to [alendronate],” concluded the researchers.
Kendler D, Chines A, Clark P, et al. Subject characteristics and changes in bone mineral density after transitioning from denosumab to alendronate in the Denosumab Adherence Preference Satisfaction (DAPS) study. Presented at: American Society for Bone and Mineral Research 2019 Annual Meeting; September 20-23, 2019; Orlando, FL. Abstract 1047.