Bone Abstracts

Introduction: Denosumab is an antiresorptive therapy for osteoporosis. In clinical studies, treatment has demonstrated statistically significant increases in BMD and reductions in fracture risk. In the ROSALIA study, the median lumbar spine bone mineral density (LS BMD) change at 52 weeks was 5% with an interquartile range of 3-8%. It is not clear why there is such a variation in the response and which baseline characteristics determine the change. In this study, we investigated baseline determinants of LS BMD change in adherent ROSALIA participants.

Methods: In the ROSALIA study, postmenopausal women with osteoporosis were randomized 1:1 to GP2411 (60 mg) or reference denosumab (REF-DMAb; 60 mg), administered at baseline and at week 26. In this analysis, the GP2411 and REF-DMAb groups were analysed together. The primary endpoint was the percentage change in LS BMD at 52 weeks. Simple and multiple linear regression models were fitted to this endpoint using baseline predictors, including baseline LS BMD value, demographics (age, race), clinical characteristics (BMI, prevalent vertebral fractures, prior bisphosphonate use), biochemical markers (PINP, serum calcium, vitamin D, and creatinine), and scanner type (Hologic or Lunar).

Results: We included 463 women in this analysis. The mean (SD) age was 64.6 (5.96) years. 91.4% were white. For LS BMD percentage change at 52 weeks, baseline PINP, serum calcium, prior bisphosphonate use, scanner type and baseline LS BMD were significant predictors (all p values 0.01). Baseline vertebral fractures, age, race, vitamin D and creatinine did not significantly predict treatment response in LS BMD.

Conclusion: In adherent denosumab participants, higher baseline PINP, higher serum calcium, no prior use of bisphosphonates and use of Lunar DXA scanner predict greater LS BMD response to denosumab therapy. These findings suggest baseline biochemical assessment may identify patients most likely to achieve robust BMD gains with denosumab, potentially informing personalised osteoporosis treatment selection in osteoporosis management.