Romosozumab and antiresorptive treatment: the importance of treatment sequence.

To evaluate whether treatment sequence affects romosozumab response, this analysis reviewed studies where romosozumab was administered before or following an antiresorptive (alendronate or denosumab). Initial treatment with romosozumab followed by an antiresorptive resulted in larger increases in bone mineral density of both hip and spine compared with the reverse sequence. INTRODUCTION: Teriparatide followed by an antiresorptive increases bone mineral density (BMD) more than using an antiresorptive first. To evaluate whether treatment sequence affects romosozumab response, we reviewed randomized clinical trials where romosozumab was administered before (ARCH, FRAME) or following (STRUCTURE, Phase 2 extension) an antiresorptive (alendronate or denosumab, respectively). METHODS: We evaluated BMD percentage change for total hip (TH) and lumbar spine (LS) and response rates (BMD gains ≥ 3% and ≥ 6%) at years 1 and 2 (except STRUCTURE with only 1-year data available). RESULTS: With 1-year romosozumab initial therapy in ARCH and FRAME, TH BMD increased 6.2% and 6.0%, and LS BMD increased 13.7% and 13.1%, respectively. When romosozumab was administered for 1 year after alendronate (STRUCTURE) or denosumab (Phase 2 extension), TH BMD increased 2.9% and 0.9%, respectively, and LS BMD increased 9.8% and 5.3%, respectively. Over 2 years, TH and LS BMD increased 7.1% and 15.2% with romosozumab/alendronate, 8.5% and 16.6% with romosozumab/denosumab, and 3.8% and 11.5% with denosumab/romosozumab, respectively. A greater proportion of patients achieved BMD gains ≥ 6% when romosozumab was used first, particularly for TH, versus the reverse sequence (69% after romosozumab/denosumab; 15% after denosumab/romosozumab). CONCLUSION: In this study, larger mean BMD increases and greater BMD responder rates were achieved when romosozumab was used before, versus after, an antiresorptive agent. Since BMD on treatment is a strong surrogate for bone strength and fracture risk, this analysis supports the thesis that initial treatment with romosozumab followed by an antiresorptive will result in greater efficacy versus the reverse sequence.

Skeletal responses to romosozumab after 12 months of denosumab.

Romosozumab, a monoclonal anti-sclerostin antibody that has the dual effect of increasing bone formation and decreasing bone resorption, reduces fracture risk within 12 months. In a post hoc, exploratory analysis, we evaluated the effects of romosozumab after 12 months of denosumab in postmenopausal women with low bone mass who had not received previous osteoporosis therapy. This phase 2 trial (NCT00896532) enrolled postmenopausal women with a lumbar spine, total hip, or femoral neck T-score ≤ -2.0 and ≥ -3.5. Individuals were randomized to placebo or various romosozumab dosing regimens from baseline to month 24, were re-randomized to 12 months of denosumab or placebo (months 24-36), and then all received romosozumab 210 mg monthly for 12 months (months 36-48). Results for the overall population have been previously published. Here, we present results for changes in bone mineral density (BMD) and levels of procollagen type I N-terminal propeptide (P1NP) and ß-isomer of the C-terminal telopeptide of type I collagen (ß-CTX) from a subset of women who were randomized to placebo for 24 months, were re-randomized to receive denosumab (n = 16) or placebo (n = 12) for 12 months, and then received romosozumab for 12 months. In women who were randomized to placebo followed by denosumab, romosozumab treatment for 12 months maintained BMD gained during denosumab treatment at the total hip (mean change from end of denosumab treatment of 0.9%) and further increased BMD gains at the lumbar spine (mean change from end of denosumab treatment of 5.3%). Upon transition to romosozumab (months 36-48), P1NP and ß-CTX levels gradually returned to baseline from their reduced values during denosumab administration. Transitioning to romosozumab after 12 months of denosumab appears to improve lumbar spine BMD and maintain total hip BMD while possibly preventing the rapid increase in levels of bone turnover markers above baseline expected upon denosumab discontinuation. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Romosozumab improves lumbar spine bone mass and bone strength parameters relative to alendronate in postmenopausal women: results from the Active-Controlled Fracture Study in Postmenopausal Women With Osteoporosis at High Risk (ARCH) trial.

The Active-Controlled Fracture Study in Postmenopausal Women With Osteoporosis at High Risk (ARCH) trial (NCT01631214; https://clinicaltrials.gov/ct2/show/NCT01631214) showed that romosozumab for 1 year followed by alendronate led to larger areal bone mineral density (aBMD) gains and superior fracture risk reduction versus alendronate alone. aBMD correlates with bone strength but does not capture all determinants of bone strength that might be differentially affected by various osteoporosis therapeutic agents. We therefore used quantitative computed tomography (QCT) and finite element analysis (FEA) to assess changes in lumbar spine volumetric bone mineral density (vBMD), bone volume, bone mineral content (BMC), and bone strength with romosozumab versus alendronate in a subset of ARCH patients. In ARCH, 4093 postmenopausal women with severe osteoporosis received monthly romosozumab 210 mg sc or weekly oral alendronate 70 mg for 12 months, followed by open-label weekly oral alendronate 70 mg for ≥12 months. Of these, 90 (49 romosozumab, 41 alendronate) enrolled in the QCT/FEA imaging substudy. QCT scans at baseline and at months 6, 12, and 24 were assessed to determine changes in integral (total), cortical, and trabecular lumbar spine vBMD and corresponding bone strength by FEA. Additional outcomes assessed include changes in aBMD, bone volume, and BMC. Romosozumab caused greater gains in lumbar spine integral, cortical, and trabecular vBMD and BMC than alendronate at months 6 and 12, with the greater gains maintained upon transition to alendronate through month 24. These improvements were accompanied by significantly greater increases in FEA bone strength (p < 0.001 at all time points). Most newly formed bone was accrued in the cortical compartment, with romosozumab showing larger absolute BMC gains than alendronate (p < 0.001 at all time points). In conclusion, romosozumab significantly improved bone mass and bone strength parameters at the lumbar spine compared with alendronate. These results are consistent with greater vertebral fracture risk reduction observed with romosozumab versus alendronate in ARCH and provide insights into structural determinants of this differential treatment effect. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Visceral adipose tissue quantification using Lunar Prodigy.

A dual-energy X-ray absorptiometry (DXA) application to measure visceral adipose tissue (VAT) in the android region of a total body DXA scan has recently been developed. This new application, CoreScan, has been validated on the Lunar iDXA (GE Healthcare, Madison, WI) densitometer against volumetric computed tomography. The geometric assumptions underlying the CoreScan model are the same on the Prodigy (GE Healthcare, Madison, WI) densitometer. However, differences between the peak X-ray voltage and detector array configurations may lead to differences in VAT quantification. The purpose of this study was to evaluate the agreement of Prodigy and iDXA CoreScan values and to characterize differences in VAT precision between the instruments. Data from volunteers with paired Prodigy and iDXA measurements were used to define empirical adjustments to the VAT algorithm parameters (n=59) and validate performance on Prodigy (n=62). Prodigy VAT measurements were highly correlated to iDXA (r=0.984). The mean of the Prodigy-iDXA VAT volume differences was -13.8cm³ with a 95% confidence interval of -45 to +17cm³. The Bland-Altman 95% limits of agreement for the 2 methods were -252 to +224cm³. Measurement of short-term precision showed that measurement error variance on iDXA was smaller (p<0.01) than Prodigy (coefficient of variance: 7.3% vs 9.8%). Precision results are in agreement with previous reports on the differences between Prodigy and iDXA for body composition measures. Prodigy and iDXA measures of VAT are similar, but the lower precision of the Prodigy may require investigators to target larger changes in VAT.