Reconstruction of Remodeling units reveals positive effects after 2 and 12 months of Romosozumab treatment.

Romosozumab treatment results in a transient early increase in bone formation and sustained decrease in bone resorption. Histomorphometric analyses revealed that the primary bone-forming effect of romosozumab is transient early stimulation of modeling-based bone formation on cancellous and endocortical surfaces; preclinical studies have demonstrated that romosozumab may affect changes in the remodeling unit resulting in positive bone balance. To further investigate the effects of romosozumab on bone balance, month 12 (M12) and M2 (to analyze early effects) unpaired bone biopsies from the FRAME clinical trial were analyzed using remodeling site reconstruction to assess whether positive changes in bone balance on cancellous/endocortical surfaces may contribute to the progressive improvement in bone mass/structure and reduced fracture risk in osteoporotic women at high fracture risk. At M12, bone balance was higher with romosozumab vs placebo on cancellous (+6.1 µm vs +1.5 µm; p = 0.012) and endocortical (+5.2 µm vs -1.7 µm; p = 0.02) surfaces; higher bone balance was due to lower final erosion depth (40.7 µm vs 43.7 µm; p = 0.05) on cancellous surfaces and higher completed wall thickness (50.8 µm vs 47.5 µm; p = 0.037) on endocortical surfaces. At M2, final erosion depth was lower on the endocortical surfaces (42.7 µm vs 50.7 µm; p = 0.021) and slightly lower on the cancellous surfaces (38.5 µm vs 44.6 µm; p = 0.11) with romosozumab vs placebo. Sector analysis of early endocortical formative sites revealed higher osteoid thickness (29.9 µm vs 19.2 µm; p = 0.005) and mineralized wall thickness (18.3 µm vs 11.9 µm; p = 0.004) with romosozumab vs placebo. These evolving bone packets may reflect early stimulation of bone formation that contributes to the increase in completed wall thickness at M12. These data suggest that romosozumab induces a positive bone balance due to its effects on bone resorption and formation at the level of the remodeling unit, contributing to the positive effects on bone mass, structure, and fracture risk.

Romosozumab treatment has a dual effect on bone, adding new bone and reducing bone loss. In the FRAME clinical trial, romosozumab increased bone mass and strength, and reduced fracture risk in postmenopausal women with osteoporosis. Addition of new bone occurs early in treatment and rapidly on cancellous and endocortical bone surfaces where bone resorption is not ongoing. However, it remains unclear if romosozumab affects bone loss or gain in areas where bone resorption is ongoing (remodeling units), contributing to a further positive bone balance. Here, we examined whether changes at the remodeling unit occur early (2 months) and/or late (12 months) in treatment, using bone biopsies from patients treated with romosozumab or placebo in FRAME. At month 2, a combination of lower bone resorption and higher bone gain on endocortical surfaces resulted in a positive bone balance with romosozumab versus placebo. At month 12, bone balance was positive with romosozumab versus placebo due to lower bone resorption on cancellous surfaces and greater bone gain on endocortical surfaces. This demonstrates that romosozumab induces a positive bone balance at remodeling units early in treatment leading to overall gains observed later, contributing to the positive effects of romosozumab on bone mass and structure.

3D-modeling from hip DXA shows improved bone structure with romosozumab followed by denosumab or alendronate.

Romosozumab treatment in women with postmenopausal osteoporosis increases bone formation while decreasing bone resorption, resulting in large BMD gains to reduce fracture risk within 1 yr. DXA-based 3D modeling of the hip was used to assess estimated changes in cortical and trabecular bone parameters and map the distribution of 3D changes in bone parameters over time in patients from 2 randomized controlled clinical trials: FRAME (romosozumab vs placebo followed by denosumab) and ARCH (romosozumab vs alendronate followed by alendronate). For each study, data from a subset of ~200 women per treatment group who had TH DXA scans at baseline and months 12 and 24 and had provided consent for future research were analyzed post hoc. 3D-SHAPER software v2.11 (3D-SHAPER Medical) was used to generate patient-specific 3D models from TH DXA scans. Percentage changes from baseline to months 12 and 24 in areal BMD (aBMD), integral volumetric BMD (vBMD), cortical thickness, cortical vBMD, cortical surface BMD (sBMD), and trabecular vBMD were evaluated. Data from 377 women from FRAME (placebo, 190; romosozumab, 187) and 368 women from ARCH (alendronate, 185; romosozumab, 183) with evaluable 3D assessments at baseline and months 12 and 24 were analyzed. At month 12, treatment with romosozumab vs placebo in FRAME and romosozumab vs alendronate in ARCH resulted in greater increases in aBMD, integral vBMD, cortical thickness, cortical vBMD, cortical sBMD, and trabecular vBMD (P < .05 for all). At month 24, cumulative gains in all parameters were greater in the romosozumab-to-denosumab vs placebo-to-denosumab sequence and romosozumab-to-alendronate vs alendronate-to-alendronate sequence (P < .05 for all). 3D-SHAPER analysis provides a novel technique for estimating changes in cortical and trabecular parameters from standard hip DXA images. These data add to the accumulating evidence that romosozumab improves hip bone density and structure, thereby contributing to the antifracture efficacy of the drug.

Osteoporosis is a chronic condition in which bones become weak and are more likely to break (fracture) with minimal force such as tripping or falling. A fracture, especially in the elderly, is a serious condition that affects daily activities and quality of life. Romosozumab, an approved medication for patients with osteoporosis, increases bone mass and bone strength thereby reducing fracture risk. In this study, 3D reproductions of patients' hip bones were generated from standard images of a bone density test with DXA from women in the FRAME clinical trial where they received romosozumab or placebo for 12 mo followed by 12 mo of denosumab or the ARCH clinical trial where they received romosozumab or alendronate for 12 mo, followed by 12 mo of alendronate. We found that patients treated with romosozumab for the first 12 mo had significantly greater increases in bone strength compared with those who received placebo or alendronate. After 24 mo, total gains in bone strength measurements were greater in patients treated with romosozumab first. Our study shows that DXA-based 3D modelling provides a novel technique for examining changes in bone strength and supports the use of romosozumab to improve hip bone strength and reduce fracture risk.

Effect of Romosozumab Treatment in Postmenopausal Women With Osteoporosis and Knee Osteoarthritis: Results From a Substudy of a Phase 3 Clinical Trial.

OBJECTIVE: Romosozumab is a bone-forming agent approved for osteoporosis treatment. Here we report results of the protocol-specified, noninferiority osteoarthritis substudy of the fracture study in postmenopausal women with osteoporosis (FRAME), which evaluated the effect of romosozumab versus placebo on knee osteoarthritis in patients with a clinical history of osteoarthritis. METHODS: Women in FRAME with a history of knee osteoarthritis were eligible for enrollment in the osteoarthritis substudy; key inclusion criteria were osteoarthritis-related signal knee pain, morning stiffness lasting less than 30 minutes, knee crepitus, and knee osteoarthritis confirmed by x-ray within 12 months. The protocol-specified outcomes were change from baseline through month 12 in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, incidence of worsening knee osteoarthritis, and treatment-emergent adverse events (TEAEs) with romosozumab versus placebo. In a post hoc analysis, percentage change from baseline to month 12 in bone mineral density (BMD) was assessed. RESULTS: Of 7180 women in FRAME, 347 participated in the osteoarthritis substudy (placebo, 177; romosozumab, 170). At month 12, no significant difference in progression of knee osteoarthritis was observed with romosozumab versus placebo (least squares mean total WOMAC score: -2.2 vs. -1.3; P = 0.71). Incidence of worsening symptoms of knee osteoarthritis was comparable between romosozumab (17.1%) and placebo (20.5%) (odds ratio 0.9 [95% confidence interval: 0.5, 1.7]; P = 0.69). Incidence of TEAEs of osteoarthritis was numerically lower with romosozumab (13 [7.7%]) versus placebo (21 [12.0%]). BMD gains were higher with romosozumab. CONCLUSION: Romosozumab treatment did not impact knee pain or function in postmenopausal women with osteoporosis and knee osteoarthritis and resulted in significant BMD gains in these women.

Romosozumab Efficacy in Postmenopausal Women With No Prior Fracture Who Fulfill Criteria for Very High Fracture Risk.

OBJECTIVE: We evaluated the efficacy of romosozumab in women from FRAME who had no prior fracture but met other criteria for very high fracture risk (VHFR). METHODS: In FRAME, postmenopausal women received romosozumab or placebo for 12 months (year 1) followed by denosumab for 12 months (year 2). In this post hoc analysis, we applied the following criteria from the American Association of Clinical Endocrinology to define VHFR: lumbar spine or total hip T-score <-3.0 and/or Fracture Risk Assessment Tool probability of major osteoporotic fracture >30% or hip fracture >4.5% to women with no fracture history at baseline (no fracture-VHFR [NF-VHFR]). Incidence of new vertebral, clinical, and nonvertebral fractures and mean bone mineral density (BMD) percentage change from baseline were assessed at years 1 and 2. RESULTS: Of the 7180 women in FRAME, 2825 were included in the NF-VHFR subgroup analysis. At year 1, romosozumab versus placebo reduced the incidence of new vertebral fracture (relative risk reduction [RRR]: 76%), clinical fracture (RRR: 60%), and nonvertebral fracture (RRR: 54%) (all P <.05). This fracture reduction was maintained through year 2 in women receiving the romosozumab-to-denosumab sequence versus the placebo-to-denosumab sequence for new vertebral, clinical, and nonvertebral fractures (RRR: 77%, 54%, and 46%, respectively; all P <.05). The mean BMD changes in both treatment groups were similar to those in the overall FRAME population at years 1 and 2. CONCLUSION: Romosozumab significantly reduced vertebral, clinical, and nonvertebral fracture risk and increased the BMD more than placebo in women at VHFR.

Modeling-Based Bone Formation After 2 Months of Romosozumab Treatment: Results From the FRAME Clinical Trial.

The bone-forming agent romosozumab is a monoclonal antibody that inhibits sclerostin, leading to increased bone formation and decreased resorption. The highest levels of bone formation markers in human patients are observed in the first 2 months of treatment. Histomorphometric analysis of bone biopsies from the phase 3 FRAME trial (NCT01575834) showed an early significant increase in bone formation with concomitant decreased resorption. Preclinical studies demonstrated that most new bone formation after romosozumab treatment was modeling-based bone formation (MBBF). Here we analyzed bone biopsies from FRAME to assess the effect of 2 months of romosozumab versus placebo on the surface extent of MBBF and remodeling-based bone formation (RBBF). In FRAME, postmenopausal women aged ≥55 years with osteoporosis were randomized 1:1 to 210 mg romosozumab or placebo sc every month for 12 months, followed by 60 mg denosumab sc every 6 months for 12 months. Participants in the bone biopsy substudy received quadruple tetracycline labeling and underwent transiliac biopsies at month 2. A total of 29 biopsies were suitable for histomorphometry. Using fluorescence microscopy, bone formation at cancellous, endocortical, and periosteal envelopes was classified based on the appearance of underlying cement lines as modeling (smooth) or remodeling (scalloped). Data were compared using the Wilcoxon rank-sum test, without multiplicity adjustment. After 2 months, the median percentage of MBBF referent to the total bone surface was significantly increased with romosozumab versus placebo on cancellous (18.0% versus 3.8%; p = 0.005) and endocortical (36.7% versus 3.0%; p = 0.001), but not on periosteal (5.0% versus 2.0%; p = 0.37) surfaces, with no significant difference in the surface extent of RBBF on all three bone surfaces. These data show that stimulation of bone formation in the first 2 months of romosozumab treatment in postmenopausal women with osteoporosis is predominately due to increased MBBF on endocortical and cancellous surfaces. © 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).