1314: Response Rates for Lumbar Spine, Total Hip, and Femoral Neck Bone Mineral Density with Abaloparatide in Men: Results from the ATOM Study

Ruban Dhaliwal¹, David Kendler², Kenneth Saag³, Steven Ing⁴, Andrea Singer⁵, Robert Adler⁶, Leny Pearman⁷, Yamei Wang⁷ and Bruce Mitlak⁸, ¹SUNY Upstate Medical University, Syracuse, NY, ²University of British Columbia, Vancouver, BC, Canada, ³University of Alabama at Birmingham, Birmingham, AL, ⁴Ohio State University Wexner Medical Center, Colombus, OH, ⁵MedStar Georgetown University Hospital, Washington, DC, ⁶Hunter Holmes McGuire Veterans Affairs Medical Center-Richmond, Richmond, VA, ⁷Radius Health, Inc., Waltham, MA, ⁸Radius Health, Inc, Boston, MA

Background/Purpose: In the Abaloparatide for the Treatment of Men with Osteoporosis (ATOM) study, 12 months of abaloparatide therapy resulted in rapid and significant improvements in bone mineral density (BMD) compared with placebo and a safety profile consistent with previous studies in postmenopausal women. The objective of this exploratory analysis was to assess the proportion of subjects from the ATOM study considered to be responders based on a >3% change in BMD and the proportion of subjects with improvement of their T-score category (osteoporosis, low BMD and normal).

Methods: Men aged 40 to 85 years were randomized to abaloparatide 80 µg (n=149) or placebo (n=79). A responder analysis by visit was conducted for subjects who had BMD measurements at Months 3, 6, and 12 at the lumbar spine (LS), total hip (TH), and femoral neck (FN). Responders were defined as subjects who had a >3% increase in BMD from baseline. The percentage of responders for abaloparatide and placebo were compared using the Chi-square test; Fisher's exact test was used if there were < 5 responders in either group. The proportion of patients with a change from baseline to Month 12 in LS and TH T-score category (normal: LS and TH T-scores ≥ -1.0; low BMD: LS T-score > -2.5 and TH T-score > -2.5 and < -1.0, or LS T-score > - 2.5 and < -1.0 and TH T-score > - 2.5; osteoporosis: LS or TH T-score ≤ -2.5) were compared using the Cochran–Mantel–Haenszel test.

Results: At Months 6 and 12, a significantly greater proportion of men treated with abaloparatide were responders at a composite of LS, TH, and FN compared with placebo (p ≤0.002, Table). A significantly greater proportion of men treated with abaloparatide vs placebo were responders as early as Month 3 for the LS and FN (LS: 61.2% vs 30.9%, p < 0.0001; FN: 32.3% vs 14.9%, p < 0.0001) (Table). At Months 6 and 12, the difference between men treated with abaloparatide and placebo was significant in favor of abaloparatide at all three individual sites (Table). At baseline, 109/228 (52.2%) had a LS T-score ≤ -2.5, and 26/228 subjects (11.4%) had a TH T-score ≤ - 2.5. A significantly greater proportion of subjects receiving abaloparatide had improvement in T-score category from baseline to end of treatment (p < 0.0001). Change from osteoporosis to low BMD or normal occurred for 42/70 (60%) and 6/47 (12.5%) of subjects receiving abaloparatide and placebo, respectively (Figure).

Conclusion: This prespecified responders analysis demonstrated that a significantly greater proportion of men with osteoporosis treated with abaloparatide vs placebo met the definition of a >3% responder at the LS, TH, and FN. Abaloparatide was associated with a significantly greater proportion of subjects with improvement in T-score category from osteoporosis to low BMD or normal than placebo.
Table. Responder Analysis

Figure. Proportion of subjects with a T-score category shift from baseline to end of treatment.
Disclosures: R. Dhaliwal, Ultragenix; D. Kendler, Radius Pharma, Amgen, Biosyent, Paladin; K. Saag, Amgen, Horizon Pharmaceuticals, LG Chem, Radius, SOBI; S. Ing, Amgen, Inc; A. Singer, Radius Health, UCB Pharma, Agnovos, Amgen Inc; R. Adler, None; L. Pearman, Radius Health; Y. Wang, Radius Health; B. Mitlak, Radius Health.