PP01-1 Effects of Denosumab on Bone Mineral Density in Treatment-Naive Patients and Patients Previously Treated with Other Osteoporosis Therapies

Program: Abstracts - Orals, Poster Previews, and Posters
Session: FRI 349-367-Osteoporosis - Risks and Treatments (posters)
Clinical
Friday, April 1, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board FRI 349
Angela Y Liu*, Mohammed Almohaya and David L Kendler
University of British Columbia, Vancouver, BC, Canada
Denosumab has been shown to increase bone mineral density (BMD) in patients with osteoporosis.  Randomized trials report that transitioning from alendronate or zoledronic acid to denosumab (DEN) leads to greater increases in BMD compared to continuing bisphosphonate therapy (1,2).  The effects of switching osteoporosis therapy likely differ between real-world clinic patients and trial patients due to patient characteristics and other factors.

To study the effect of DEN in treatment-naive patients and patients switched from other osteoporosis therapies in a real-world clinic setting, we conducted a retrospective chart review of all patients treated with DEN at an osteoporosis referral centre in Vancouver, Canada.  The study group consisted of all males and females treated with DEN 60 mg SC every six months for at least one year, and in whom baseline and follow-up BMD data were available.  Annual BMD measurements at either hip or spine were performed at the site with the lowest T-score.  Patients were either treatment-naive when starting DEN, or switched from one of four medications: alendronate (ALE), risedronate (RIS), zoledronic acid (ZOL), or teriparatide (TER).  Data analysis was conducted using ANOVA with Bonferroni correction for multiple comparisons.

758 consecutive patients were included: 310 followed at the hip and 448 followed at the spine.  Baseline characteristics were similar between hip and spine follow-up groups.  Treatment-naive and all prior-treatment groups increased BMD on DEN.  Responder analysis showed that 52% and 87% of patients followed at the hip and spine respectively had increased BMD by more than 3% by the end of follow-up at 4 years.  Treatment-naive patients showed a greater increase in hip BMD on DEN compared to patients switching from ZOL after 1 year (p=0.006).  This difference persisted at 3 years (p=0.005).  Treatment-naive patients followed with spine BMD also showed a greater response to DEN compared to those switching from ZOL after 1 year (p=0.007).  Patients switched from ALE, RIS, and TER showed similar increases in hip or spine BMD compared to treatment-naive patients initiating DEN therapy.

Consistent with reported data from clinical trials, DEN increased BMD at hip and spine both in treatment-naive and in patients switching from prior osteoporosis therapy.  The observed increase in BMD was greater than reported in controlled trials (1,3).  Lower adherence to preceding therapy and the use of generic bisphosphonates in clinic patients may account for some of this difference.  There is also greater variability in clinic patient characteristics compared to clinical trial participants.  Our results will inform clinicians regarding anticipated improvements in BMD when transitioning to denosumab.

(1) Kendler DL, Roux C et al. Effects of denosumab on bone mineral density and bone turnover in postmenopausal women transitioning from alendronate therapy. J Bone Miner Res. 2010;25:72-81. (2) Anastasilakis AD, Polyzos SA et al. Denosumab vs. zoledronic acid in patients previously treated with zoledronic acid. Osteoporos Int. 2015;26:2521-2527. (3) Recknor C, Czerwinksi E et al. Denosumab compared with ibadronate in postmenopausal women previously treated with bisphosphonate therapy. Obstet Gynecol. 2013;121:1291-9.

Disclosure: DLK: Consultant, Amgen, Consultant, Eli Lilly & Company, Consultant, Merck & Co., Consultant, GlaxoSmithKline, Consultant, Astra Zeneca. Nothing to Disclose: AYL, MA

*Please take note of The Endocrine Society's News Embargo Policy at https://www.endocrine.org/news-room/endo-annual-meeting/pr-resources-for-endo