Three months of romosozumab did not improve hip bone strength, but 12 months did, supporting completion of the full regimen in patients with osteoporosis.
Three months of romosozumab (Evenity) produced only modest, nonsignificant gains in hip bone strength and total hip volumetric bone mineral density (vBMD) among postmenopausal women with osteoporosis, whereas both measures increased substantially by 12 months, according to real-world data presented at the American Society for Bone and Mineral Research (ASBMR) 2026 Annual Meeting.¹
In a new interview with the team at HCPLive, lead investigator Koji Ishikawa, MD, PhD, senior research associate in the Alman Lab at Duke Orthopaedic Surgery, discussed the findings and their implications for patients considering early discontinuation.
Romosozumab is an anti-sclerostin antibody approved as a 12-month course for severe osteoporosis, and Ishikawa described it as among the most effective agents for increasing bone mineral density and reducing future fracture risk, with relatively rapid onset. His group previously reported improvements in vertebral bone mineral density and strength after only 3 months of treatment. Whether the hip responds on a similar timeline had not been established.
The question carries practical weight, Ishikawa explained, because recent studies have explored switching to another agent, such as denosumab, after a shorter romosozumab course. If the hip gains little during short-term treatment, clinicians may need to exercise caution before stopping romosozumab early.
Investigators conducted a retrospective observational study of Japanese postmenopausal women with osteoporosis who initiated romosozumab 210 mg monthly in routine clinical practice, completed 12 months of treatment, and had received no osteoporosis medication in the prior 3 years. Hip bone strength and total hip vBMD were assessed at baseline, 3 months, and 12 months using US Food and Drug Administration–cleared biomechanical computed tomography (BCT) applied to CT scans obtained during routine care, with analyses performed in a blinded manner.
Ishikawa noted DXA remains the conventional measure of treatment efficacy, but as a 2-dimensional technique it may not fully reflect the strength of a complex structure such as the hip. Biomechanical strength relates more directly to fracture risk, and the group conducted the analysis in collaboration with Tony M. Keaveny, PhD, of the University of California, Berkeley.
At 3 months, hip bone strength increased by 1.4% (95% CI, −2.2% to 5.0%) and vBMD by 2.0% (95% CI, −0.1% to 4.1%), neither reaching significance.¹ At 12 months, hip bone strength increased by 7.4% (95% CI, 5.2% to 9.6%) and vBMD by 5.4% (95% CI, 4.0% to 6.9%), gains roughly 2 to 5 times larger than those at 3 months.
Ishikawa attributed the slower hip response to structural differences between sites. The spine contains a larger proportion of trabecular bone, while the hip contains more cortical bone and a more complex architecture, though the study cannot establish the underlying mechanism.
Given the consequences of hip fracture for mortality, mobility, and daily function, Ishikawa advised clinicians to discuss with patients and families why completing the full 12-month course may be important when early discontinuation or switching is under consideration, while respecting patient decisions. His group is also conducting a randomized controlled trial to define the optimal treatment sequence after 12 months of romosozumab.
Ishikawa reported serving as a consultant to Amgen and receiving grant or research support from the company.
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