Bone-Forming and Antiresorptive Effects of Romosozumab in Postmenopausal Women With Osteoporosis: Bone Histomorphometry and Microcomputed Tomography Analysis After 2 and 12 Months of Treatment

Mechanisms of isorhamnetin inhibition of osteoclast differentiation: insights from molecular dynamics simulations and in vitro/in vivo experiments

Background

Osteoporosis (OP) represents a widespread bone remodeling disorder within the domain of orthopedics, markedly compromising the quality of life in the elderly population. The need to develop more efficient therapeutic approaches to attenuate bone resorption by suppressing the excessive activation of osteoclasts (OCs) remains urgent. The plant flavonoid Isorhamnetin (Iso), recognized for its potent antioxidant properties, has been the subject of extensive research regarding its potential in treating bone-related conditions.

Method

This study adopts a comprehensive methodology to evaluate Iso's impact on bone metabolism and its therapeutic possibilities for treating OP. By integrating network pharmacology, molecular dynamics simulations, and surface plasmon resonance (SPR), we performed in vitro phenotypic analyses to systematically evaluate the inhibitory effect of Iso on OC differentiation. The mechanisms behind Iso's inhibition of OC differentiation were further elucidated. In vivo testing was also performed to substantiate the therapeutic effects of Iso in an OP animal model.

Results

At low concentrations, Iso showed no cytotoxicity and did not interfere with cell proliferation in RAW 264.7 cells. Iso effectively inhibited RANKL-induced osteoclast differentiation in these cells, while downregulating related genes levels (Nfatc1, Ctsk, Trap, c-Fos). Molecular dynamics simulations and surface plasmon resonance confirmed Iso's dual binding to both RANKL and RANK. KEGG pathway enrichment analysis results indicated that Iso modulates the MAPK, NF-κB/PI3K-AKT, and calcium signaling pathways. Western blot analysis revealed that Iso treatment targeting the RANKL/RANK binding pathway significantly downregulated phosphorylation levels of JNK, P38, AKT, and p65. Concurrently, Iso stimulation markedly increased IκBα expression, thereby rescuing its degradation. Furthermore, Iso demonstrated a robust inhibitory effect on reactive oxygen species levels in vitro. Furthermore, in OVX mice, Iso treatment increased bone density, modulated serum bone metabolism markers, and downregulated transcriptional levels of OC marker genes.

Conclusion

Iso exhibits therapeutic potential for OP by selectively targeting and disrupting the RANKL-RANK interaction. This intervention modulates the expression of intracellular transcription factors and multiple signaling pathways, thereby inhibiting the maturation of OCs. Through mitigating OC-mediated bone loss, Iso holds significant promise as a potent therapeutic agent for OP.

The Effectiveness and Safety of Romosozumab and Teriparatide in Postmenopausal Women With Osteoporosis

PURPOSE

The purpose of this observational study was to investigate the effectiveness and safety of romosozumab (ROMO) and teriparatide (TPTD) in a clinical setting.

METHODS

A total of 315 postmenopausal women were included based on the reimbursement criteria for ROMO and TPTD at the Department of Endocrinology at Aarhus University Hospital. Criteria for ROMO were bone mineral density (BMD) T-score < -2.5 (femoral neck [FN], total hip [TH], or lumbar spine [LS]) + a fragility fracture (hip, spine, pelvis, distal forearm, or proximal humerus) within 3 years. Criteria for TPTD: within 3 years, ≥ 2 vertebral fractures or 1 vertebral fracture + BMD T-score (FN, TH, or LS) < -3. Data were collected from medical records. The primary end point was percentage change from baseline in BMD (FN, TH, and LS) at month 12. BMD was measured by dual-energy x-ray absorptiometry (DXA).

RESULTS

At month 12, ROMO led to significantly (P < .001) larger increases than TPTD in BMD (FN: 4.8% vs 0.2%, TH: 5.7% vs 0.3%, and LS: 13.7% vs 9.3%). Discontinuation rate was lower with ROMO than with TPTD. Lower incidence of cardiovascular adverse events was observed with ROMO compared to TPTD. Treatment-naïve patients had nonsignificantly higher BMD increases compared to previously treated patients with both ROMO and TPTD.

CONCLUSION

Treatment with ROMO yields larger increases in BMD than TPTD after 12 months and a higher rate of completion. ROMO was associated with a higher adherence.

Sequential and Long-term Therapy for Osteoporosis

PURPOSE OF THE REVIEW

Osteoporosis requires life-long management. This involves the use of different drugs in various sequences followed by long-term maintenance therapy. This review highlights the important transitions among osteoporosis therapies and outlines a strategy of intermittent bisphosphonate therapy for long-term maintenance.

RECENT FINDINGS

Over the past few years, the effects and limitations of long-term treatment with bisphosphonates and denosumab have become apparent as have several key factors in the sequential use of anti-remodeling drugs and osteoanabolic agents. Strategies for transitions from estrogen, bisphosphonates, denosumab and the bone-forming drugs will be discussed, based on extant evidence, clinical experience and expert opinion. By appropriate selection of both the initial and subsequent drugs for the prevention and treatment of osteoporosis, therapeutic benefits can be optimized and safety issues minimized. Developing a strategy for long-term maintenance of the benefits of the initial therapies can provide a life plan for managing patients with osteoporosis.

L5 osteotomy combined with adjuvant romosozumab therapy for L5 osteoporotic vertebral fracture-induced spinal deformity: illustrative case

BACKGROUND

Spinal reconstruction of an L5 osteoporotic vertebral fracture (OVF) is a demanding surgery because of the condition's rarity, poor bone quality, and anatomical reasons. To date, there has been little debate regarding the surgical strategy for L5 OVF and effective osteoporosis treatment. The authors report L5 osteotomy and adjuvant romosozumab (ROMO) therapy for L5 OVF-induced spinal deformity.

OBSERVATIONS

A 73-year-old woman underwent lumbopelvic instrumentation and fusion from L3 to the pelvis, L5 osteotomy combined with unilateral posterior vertebral column resection (VCR), followed by expandable cage replacement and bone biopsy simultaneously. Histomorphometric analysis of the bone biopsy showed accelerated bone formation in the endocortical region of the spinous process. After surgery, her low back pain and leg pain improved with satisfactory global alignment. At the 2-year follow-up, lumbopelvic reconstruction achieved fusion, with minimal reciprocal change and no mechanical failure. The patient's Oswestry Disability Index improved from 64% to 24%. L5 osteotomy combined with unilateral VCR and expandable cage replacement was a safe and effective technique in this case.

LESSONS

This technique can provide both greater restoration of lower lumbar lordosis and pelvic tilt with fusion. Moreover, adjuvant ROMO therapy has the potential to prevent osteoporosis-related complications. https://thejns.org/doi/10.3171/CASE24633.

Comparative Analysis of Romosozumab Versus Vertebroplasty With Denosumab: Efficacy, Safety, and Secondary Bone Mineral Density Outcomes

OBJECTIVE

This study aimed to compare the efficacy and safety of romosozumab, a bone anabolic agent, versus vertebroplasty, a conventional surgical intervention, in treating osteoporotic vertebral compression fractures (OVCFs).

METHODS

A retrospective analysis included 86 thoracic/lumbar compression fracture patients from 2014 to 2022 at a medical center. Forty-two patients received romosozumab (monthly injections for 1 year) followed by 1 year of denosumab, while 44 underwent vertebroplasty followed by denosumab injections biannually for 2 years. Outcomes were assessed using the Numerical Rating Scale (NRS) for pain, bone mineral density (BMD), vertebral compression ratio, and Cobb angle over 12 months.

RESULTS

At 12 months, the romosozumab group showed a greater reduction in NRS scores (4.90 ± 1.01 vs. 4.27 ± 1.34, p = 0.015) and a higher increase in lumbar BMD (0.8 ± 0.5 vs. 0.5 ± 0.3, p = 0.000) compared to the vertebroplasty group. There were no significant differences in changes in hip total BMD and femur neck BMD (p = 0.190, p = 0.167, respectively). Radiographic assessments showed no significant differences in vertebral compression ratio (14.7% vs. 14.8%; p = 0.960) or Cobb angle (4.2° vs. 4.9°; p = 0.302). The incidence of major osteoporotic fractures was lower in the romosozumab group (7.1% vs. 25.0%, p = 0.051), with similar rates of cardiovascular events in both groups (4.8% vs. 9.1%, p = 0.716).

CONCLUSION

Romosozumab has demonstrated superior pain reduction and lumbar BMD improvement compared to vertebroplasty at 12 months, with no significant differences in radiographic outcomes or adverse events, suggesting it as an alternative to vertebroplasty for OVCF.

Assessment of evidence for the off-label application of osteoanabolic drugs in fracture healing and spinal fusion

Osteoanabolic drugs are sometimes prescribed off-label for "fracture healing and spinal fusion." This study examines the scientific validity of such practices by analyzing existing clinical reports. The purported bone union-promoting effect of teriparatide in fracture cases has been refuted in clinical trials. While teriparatide shows efficacy in accelerating spinal fusion after surgery for patients with osteoporosis, there is no scientific justification for its off-label use in patients without osteoporosis. For osteoporosis patients, no clear evidence suggests that teriparatide is superior to antiresorptive drugs, making the rationale for switching from antiresorptive drugs to teriparatide weak. The efficacy in postoperative spinal fusion may primarily be attributed to systemic improvements in bone quality and quantity, enhancing the mechanical engagement of implants. The clinical evidence for the off-label use of romosozumab, another osteoanabolic drug, in fracture healing and spinal fusion is insufficient to support its efficacy. In conclusion, osteoanabolic drugs, like antiresorptive drugs, primarily have systemic functions in osteoporosis patients, with limited evidence supporting their role in promoting localized bone formation in fractures or spinal fusions.

Τhe story of sclerostin inhibition: the past, the present, and the future

Sclerostin inhibits osteoblast activity by hampering activation of the canonical Wnt signaling pathway and simultaneously stimulates osteoclastogenesis through upregulation of the receptor activator of NFκB ligand (RANKL). Thus, antibodies against sclerostin (Scl-Abs), besides promoting bone formation, suppress bone resorption and dissociate bone formation from resorption. This dual action results in remarkable increases of bone mineral density which are of a greater magnitude compared to the other antiosteoporotic treatments and are accompanied by decreases of fracture risk at all skeletal sites. The anabolic effect subsides after the first few months of treatment and a predominantly antiresorptive effect remains after this period, limiting its use to 12 months. Furthermore, these effects are largely reversible upon discontinuation; therefore, subsequent treatment with antiresorptives is indicated to maintain or further increase the bone gains achieved. Romosozumab is currently the only Scl-Ab approved for the treatment of severe postmenopausal osteoporosis. Indications for use in other populations, such as males, premenopausal women, and patients with glucocorticoid-induced osteoporosis, are pending. Additionally, the efficacy of Scl-Abs in other bone diseases, such as osteogenesis imperfecta, hypophosphatasia, X-linked hypophosphatemia, and bone loss associated with malignancies, is under thorough investigation. Cardiovascular safety concerns currently exclude patients at high cardiovascular risk from this treatment.

Effect of romosozumab on bone mineral density and trabecular bone score in premenopausal women with low bone mass

We investigated the efficacy of romosozumab in premenopausal women with low bone mass. Romosozumab substantially increased bone mineral density and trabecular bone score in these women, aligning with its proven therapeutic benefits for postmenopausal osteoporosis.

PURPOSE

Romosozumab, an anti-sclerostin antibody, is a promising anabolic agent that increases bone formation and decreases bone resorption. However, its efficacy in premenopausal women with low bone mass remains understudied.

METHODS

We retrospectively reviewed premenopausal women with low bone mass treated with romosozumab (ROMO group) or drug-naïve patients (control group). Patients in the ROMO group were classified into the glucocorticoid-induced osteoporosis (GIOP), idiopathic osteoporosis (IOP), and pregnancy and lactation-induced osteoporosis (PLO) subgroups. Bone mineral density (BMD) and trabecular bone score (TBS) were measured before and after one year of romosozumab treatment.

RESULTS

Twenty-five patients in the ROMO group and five in the control group were included in the study. Among patients in the ROMO group, 12 were in the GIOP, 9 in the IOP, and 4 in the PLO subgroups. The mean age was 37.0 years [32.0-42.0], and the median body mass index was 18.8 kg/m2 [17.5-21.3]. After romosozumab treatment, lumbar spine (LS), femur neck (FN) BMD, and TBS increased from baseline (LSBMD, 12.8% [8.2-19.3], p < 0.001; FNBMD, 4.6% [- 0.6-10.7], p = 0.016; TBS, 4.1% ± 3.8, p < 0.001) in the ROMO group. Patients in both the GIOP and IOP subgroups showed a significant increase in LSBMD, while those in the IOP subgroup demonstrated significant increases in FNBMD.

CONCLUSION

We demonstrated romosozumab's efficacy in BMD increment in premenopausal women. Romosozumab may be a potential treatment option for premenopausal women with low bone mass, regardless of etiologies, although further research on fracture risk reduction is warranted.

Mechanical Analysis of Romosozumab's Effects on Bone Strength in a Rat Posterolateral Lumbar Fusion Model

PURPOSE

 This study aimed to evaluate the effects of romosozumab, a humanized monoclonal antibody, on bone healing and mechanical strength in a rat posterolateral lumbar fusion (PLF) model. The primary objective was to determine its potential in promoting bone union and enhancing the structural integrity of graft sites, addressing challenges such as pseudarthrosis and hardware failure in spinal surgeries. These complications are particularly common in osteoporotic patients, where compromised bone quality and reduced healing capacity significantly increase the risk of surgical failure. With an aging global population, osteoporosis-related complications in spinal surgery are expected to rise, necessitating novel interventions to improve outcomes.

MATERIALS AND METHODS

 Twenty male Sprague-Dawley rats were randomized into two groups: romosozumab-treated (R) and control (C). All animals underwent bilateral PLF surgery involving the placement of autogenous bone grafts harvested from the spinous process combined with a demineralized bone matrix between the transverse processes of the lumbar vertebrae. Subcutaneous injections of romosozumab (105 mg/1.17 mL) or saline were administered twice weekly for 10 weeks. Bone healing was assessed through micro-computed tomography (CT) imaging at baseline and 10 weeks post-surgery. Key metrics included the bone fusion rate, fused bone volume, and bone mineral density (BMD). Additionally, the mechanical strength of the fusion mass was evaluated using a three-point bending test to determine the force required to induce rupture.

RESULTS

 The R group exhibited significant improvements across all evaluated parameters compared to the C group. Fused bone volume in the R group was significantly greater at 10 weeks (826.7 ± 27.5 mm³) compared to the C group (652.6 ± 30.7 mm³, p < 0.05), reflecting a higher bone volume growth rate (158.1 ± 12.9% vs. 106.8 ± 10.4%, p < 0.05). BMD at the distal femoral diaphysis was also markedly increased in the R group (830.2 ± 11.1 mgHA/cm³) compared to the C group (725.5 ± 12.1 mgHA/cm³, p < 0.05). Mechanical testing revealed superior compressive strength in the R group, with a rupture force of 312.5 ± 43.2 N versus 209.3 ± 35.4 N in the C group (p < 0.05). These results demonstrate romosozumab's capacity to promote robust bone formation and significantly enhance the mechanical integrity of the fusion mass.

CONCLUSION

Romosozumab treatment significantly improved bone healing, mineral density, and mechanical strength in a rat PLF model, suggesting its potential as a therapeutic option for enhancing spinal surgery outcomes. By promoting rapid bone formation and increasing bone strength, romosozumab addresses critical challenges such as pseudarthrosis and pedicle screw loosening, which frequently compromise surgical success, especially in osteoporotic patients. These findings underscore the therapeutic promise of romosozumab not only in spinal surgery but also as a broader intervention for bone repair and healing. Further research is needed to explore its dose-response relationship, long-term safety, and efficacy in osteoporotic models. Moreover, the use of biochemical markers and microstructural analyses will help elucidate the underlying mechanisms of its action. With its demonstrated ability to enhance both structural and functional bone properties, romosozumab offers a promising avenue for advancing spinal surgery and improving patient outcomes.

Romosozumab adverse event profile: a pharmacovigilance analysis based on the FDA Adverse Event Reporting System (FAERS) from 2019 to 2023

OBJECTIVE

This study aims to analyze adverse drug events (ADE) related to romosozumab from the second quarter of 2019 to the third quarter of 2023 from FAERS database.

METHODS

The ADE data related to romosozumab from 2019 Q2 to 2023 Q3 were collected. After data normalization, four signal strength quantification algorithms were used: ROR (Reporting Odds Ratios), PRR (Proportional Reporting Ratios), BCPNN (Bayesian Confidence Propagation Neural Network), and EBGM (Empirical Bayesian Geometric Mean).

RESULTS

Screening for romosozumab-related AEs (adverse events) included 23 system organ categories (SOCs). PT (preferred terms) levels were screened for adverse drug reaction (ADR) signals. A total of 7055 reports with romosozumab as the primary suspect (PS) and 14,041 PTs induced by romosozumab as PS were identified. Common significant signals of general disorders and administration site conditions, musculoskeletal and connective tissue disorders have emerged. Specifically, unexpected AEs such as gastrointestinal disorder, respiratory, thoracic and mediastinal disorders also occur. Notably, fracture (n = 503, ROR = 107.8, PRR = 103.83, IC = 6.6, EBGM = 97.02) and bone density abnormal (n = 429, ROR = 343.65, PRR = 332.77, IC = 8.08, EBGM = 271.34) exhibited relatively high occurrence rates and signal strengths.

CONCLUSION

Our study identifies potential new AE signals and provides broader data support for the safety of romosozumab. In clinical application, doctors are provided with a warning to closely monitor adverse reactions to support their rational use in diseases such as osteoporosis.

Cardiovascular Safety of Romosozumab Compared to Commonly Used Anti-osteoporosis Medications in Postmenopausal Osteoporosis: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

INTRODUCTION

The aim of this study was to investigate the cardiovascular safety of romosozumab in postmenopausal women with osteoporosis. Romosozumab, a monoclonal antibody targeting sclerostin, has been shown to increase bone mineral density and reduce the risk of osteoporotic fractures. However, in previous studies, romosozumab therapy was identified as a potential risk factor for cardiovascular events, particularly in patients with predisposing cardiovascular disease.

METHODS

A systematic literature search was performed in the Cochrane Library, Embase, PubMed, and Web of Science databases to identify randomized controlled trials (RCTs) comparing the safety and efficacy of romosozumab versus alendronate, teriparatide, denosumab, or placebo in postmenopausal women with osteoporosis. Contrast-based network meta-analysis was performed using a random-effects model. The pooled estimates are presented as risk ratios with 95% confidence intervals.

RESULTS

Of the 5282 articles retrieved, 25 RCTs were included in this review (n = 24,942), and 18 randomized controlled trials (n = 16,777) were included in the network meta-analysis. The results indicated no significant differences in cardiovascular mortality rate between romosozumab and placebo. Regarding the risk of major cardiovascular events, no significant differences were found in the direct evidence or the network meta-analysis with placebo as the reference.

CONCLUSION

Romosozumab might be a safe option for treating postmenopausal women with osteoporosis. The cardiovascular concerns associated with this treatment seem less significant than previously suggested, although additional real-world data are required to confirm this conclusion.

Clinical effects of teriparatide, abaloparatide, and romosozumab in postmenopausal osteoporosis

In the management of osteoporosis, anti-resorptive agents serve as a primary therapeutic approach. However, in cases where individuals exhibit an increased susceptibility to fractures, such as those characterized by severe low bone mass or a history of vertebral or hip fractures that markedly diminish life expectancy, the immediate reduction of fracture risk through the administration of osteoanabolic agents could be beneficial. Teriparatide, available in daily, once-weekly, or twice-weekly dosages, along with abaloparatide and romosozumab, constitutes a trio of such agents. Each of these medications is defined by unique characteristics, distinct efficacy profiles, and specific adverse effects. There is growing evidence to suggest that these agents have a superior effect on enhancing bone mineral density and reducing fracture incidence when compared to traditional bisphosphonate therapies. Nonetheless, their employment demands thorough consideration of clinical indications, which includes evaluating economic factors, the frequency of injections required, and the potential for adverse effects. The objective of this review is to consolidate the current evidence focusing primarily on the efficacy of these agents, with the goal of enhancing understanding and aiding in making more informed treatment decisions, particularly for those individuals who are at an elevated risk of fractures.

Disparate effects of sclerostin deletion on alveolar bone and cellular cementum in mice

BACKGROUND

Cellular cementum (CC) includes cementocytes, cells suspected to regulate CC formation or resorption as osteocytes do in bone. Sclerostin (SOST) is a secreted negative regulator of Wnt/β-catenin signaling expressed by osteocytes and cementocytes. Osteocyte SOST expression reduces bone formation. We investigated the functional importance of SOST in CC compared with alveolar bone (AB) using a Sost knockout (Sost-/-) mouse model to better understand the role of cementocytes in CC.

METHODS

Mandibles and femurs of Sost-/- and wild-type (WT) mice were analyzed at 42 and 120 days postnatal (dpn). Maxillary first molars were bilaterally extracted at 42 dpn and both AB healing (maxillary molar sockets) and CC apposition (mandibular first molars) were examined at 21 days post-procedure. Analyses included micro-computed tomography, histology, and immunohistochemistry.

RESULTS

Femur cortical and trabecular bone and mandibular bone volumes were similarly increased in Sost-/- versus WT mice at 42 and/or 120 dpn. In contrast to previous reports, CC was not increased by Sost-/- at either age. We conducted challenge experiments on AB and CC to explore tissue-specific responses. Post-extraction AB healing was improved by Sost deletion. In contrast, experimentally-induced apposition in molars failed to stimulate increased CC formation in Sost-/- versus WT mice. Wnt pathway markers AXIN2 and DKK1, which were increased in Sost-/- versus WT AB osteocytes, were unchanged in cementocytes.

CONCLUSIONS

These data indicate CC is less responsive than AB to SOST deletion. Within the study limitations, these results do not support cementocytes as critical for directing increased CC formation.

PLAIN LANGUAGE SUMMARY

Sclerostin is a protein known to inhibit bone formation, and removing sclerostin leads to more bone formation. Cementum is the thin layer that covers the surface of the tooth's root. Previous studies suggest that inhibiting sclerostin can similarly increase the amount of cementum. We wanted to compare the response of cementum and bone when sclerostin is absent to understand similarities and differences between these two tissues. In this study, we removed the Sost gene (the gene which produces sclerostin) in mice. We found that mice without sclerostin have more bone in their legs and jaws. Moreover, mice without sclerostin also healed better after tooth removal compared with normal mice. Surprisingly, unlike previous studies, we found that the amount of cementum was not different in mice without sclerostin compared with normal mice. Additionally, we challenged the cementum by taking out the opposing tooth to cause the first mandibular molar to move up by building more cementum. Even with this challenge, we found no difference in the amount of cementum in mice lacking sclerostin compared with normal mice. Therefore, we conclude here that cementum is less sensitive to the absence of sclerostin compared with bone.

Effect of romosozumab administration on proximal junctional kyphosis in corrective spinal fusion surgery

BACKGROUND CONTEXT

The effect of romosozumab administration in patients undergoing corrective spinal fusion surgery has not yet been analyzed.

PURPOSE

To examine the effect of romosozumab administration on reducing the incidence of proximal junctional kyphosis (PJK), particularly PJK due to fractures (PJK-Fx), in patients undergoing spinal corrective fusion surgery.

DESIGN

Retrospective cohort study PATIENT SAMPLE: A total of 111 patients aged >50 years underwent corrective fusion surgery (>2 vertebrae) for adult spinal deformity or vertebral compression fracture between June 2010 and July 2023.

OUTCOME MEASURES

The primary outcome was the incidence of PJK, whereas the secondary outcomes were changes in Hounsfield unit (HU) values, surgical complications, and clinical outcomes measured using the Japanese Orthopaedic Association (JOA) and visual analog scale scores.

METHODS

The patients were divided into the romosozumab (n=32) and non-romosozumab groups (n=79). Romosozumab was typically administered 2 months before surgery in the romosozumab group. Demographic data, surgery-related factors, and radiographic parameters were analyzed. HU values at the upper instrumented vertebra+1 (UIV+1) were measured preoperatively and at 1 year postoperatively. After the univariate analysis of preoperative factors associated with PJK, multivariate logistic regression was used to identify factors associated with PJK.

RESULTS

Romosozumab significantly increased the HU values at UIV+1 (-1.22% vs. 13.60%, p<0.001) and reduced the incidence of PJK (39.24% vs. 18.75%, p=0.046), particularly PJK-Fx (26.58% vs. 6.25%, p=0.019) and osteoporosis-related complications (55.70% vs. 34.38%, p=0.011). The multivariate analysis showed a significantly lower incidence of PJK (adjusted odds ratio = 0.32, p=0.033), particularly PJK-Fx (adjusted odds ratio = 0.15, p=0.018). There was a tendency for better JOA scores at 1 year postoperatively in the romosozumab group (21.49 vs. 23.62, p=0.071).

CONCLUSION

Romosozumab administration effectively increased bone density and reduced the risk of PJK, particularly PJK-Fx, and osteoporosis-related complications in patients undergoing corrective spinal fusion surgery. Administration of romosozumab 2 months before surgery enhanced bone mineral density and strength, leading to better surgical outcomes and fewer complications. Further long-term studies are needed to confirm these findings and optimize treatment protocols.

A practical approach for anabolic treatment of bone fragility with romosozumab

BACKGROUND

Romosozumab, a fully humanized anti-sclerostin-antibody, is a bone-builder stimulating osteoblasts and inhibiting osteoclast by activation of the canonical Wnt-beta catenin signaling. This unique mechanism of action has the potential to address unmet needs in osteoporosis management.

METHODS

The multifaceted practical clinical issues related to romosozumab are discussed, especially focusing on the rationale of employing a sclerostin inhibitor to target bone fragility as first line or second line treatment in post-menopausal osteoporosis and in males at increased risk of fractures.

RESULTS

Four randomized clinical trials with several post-hoc analyses and more than ten observational studies have consistently demonstrated that romosozumab is effective in rapidly increasing bone mineral density (BMD) and decreasing risk of vertebral, non-vertebral and hip fractures in post-menopausal women at very-high risk of fractures. In male osteoporosis, only data on BMD are available. Noteworthy, romosozumab was shown to be more effective and rapid than teriparatide in improving BMD, bone structure and strength at the hip, especially in women already treated with anti-resorptive drugs. Interestingly, even if romosozumab displays best results in treatment-naïve patients, its favourable effects on BMD were observed even in women previously treated with teriparatide or denosumab, although to a lesser extent.

CONCLUSIONS

Based on the available evidence, romosozumab could be proposed as ideal drug in several clinical settings, such as non-fractured post-menopausal women at very-high risk of fractures, patients with recent hip fracture, patients non responder to bisphosphonates and short-term denosumab therapy.

Bone Disease in Primary Hyperparathyroidism-Changes Occurring in Bone Metabolism and New Potential Treatment Strategies

Primary hyperparathyroidism (PHPT) is a common endocrinopathy, predominantly caused by a single parathyroid adenoma that is responsible for the excessive secretion of parathyroid hormone (PTH)-the hallmark of disease. Excess of this hormone causes remarkable changes in bone metabolism, including an increased level of bone remodeling with a predominance of bone resorption. Those changes lead to deterioration of bone structure and density, especially in cortical bone. The main treatment for PHPT is surgical removal of the adenoma, which normalizes PTH levels and terminates the progression of bone disease and leads to its regeneration. However, because not all the patients are suitable candidates for surgery, alternative therapies are needed. Current non-surgical treatments targeting bone disease secondary to PHPT include bisphosphonates and denosumab. Those antiresorptives prevent further bone loss, but they lack the ability to regenerate already degraded bone. There is ongoing research to find targeted drugs capable of halting resorption alongside stimulating bone formation. This review presents the advancements in understanding the molecular mechanisms responsible for bone disease in PHPT and assesses the efficacy of new potential therapeutic approaches (e.g., allosteric inhibitors of the PTH receptor, V-ATPase, or cathepsin inhibitors) aimed at mitigating bone loss and enhancing bone regeneration in affected patients.

IMPC-based screening revealed that ROBO1 can regulate osteoporosis by inhibiting osteogenic differentiation

Introduction

The utilization of denosumab in treating osteoporosis highlights promising prospects for osteoporosis intervention guided by gene targets. While omics-based research into osteoporosis pathogenesis yields a plethora of potential gene targets for clinical transformation, identifying effective gene targets has posed challenges.

Methods

We first queried the omics data of osteoporosis clinical samples on PubMed, used International Mouse Phenotyping Consortium (IMPC) to screen differentially expressed genes, and conducted preliminary functional verification of candidate genes in human Saos2 cells through osteogenic differentiation and mineralization experiments. We then selected the candidate genes with the most significant effects on osteogenic differentiation and further verified the osteogenic differentiation and mineralization functions in mouse 3T3-E1 and bone marrow mesenchymal stem cells (BMSC). Finally, we used RNA-seq to explore the regulation of osteogenesis by the target gene.

Results

We identified PPP2R2A, RRBP1, HSPB6, SLC22A15, ADAMTS4, ATP8B1, CTNNB1, ROBO1, and EFR3B, which may contribute to osteoporosis. ROBO1 was the most significant regulator of osteogenesis in both human and mouse osteoblast. The inhibitory effect of Robo1 knockdown on osteogenic differentiation may be related to the activation of inflammatory signaling pathways.

Conclusion

Our study provides several novel molecular mechanisms involved in the pathogenesis of osteoporosis. ROBO1 is a potential target for osteoporosis intervention.

Role of sclerostin deletion in bisphosphonate-induced osteonecrosis of the jaw

PURPOSE

Bone resorption inhibitors, such as bisphosphonates (BP) and denosumab, are frequently used for the management of osteoporosis. Although both drugs reduce the risk of osteoporotic fractures, they are associated with a serious side effect known as medication-related osteonecrosis of the jaw (MRONJ). Sclerostin antibodies (romosozumab) increase bone formation and decrease the risk of osteoporotic fractures: however, their anti-resorptive effect increases ONJ. Thus, this study aimed to elucidate the role of sclerostin deletion in the development of MRONJ.

METHODS

Sclerostin knockout (SostΔ26/Δ26) mice were used to confirm the development of ONJ by performing tooth extractions. To confirm the role of sclerostin deficiency in a more ONJ-prone situation, we used the BP-induced ONJ model in combination with severe periodontitis to evaluate the development of ONJ and bone formation in wild-type (WT) and SostΔ26/Δ26 mice. Wound healing assay using gingival fibroblasts with or without sclerostin stimulation and tooth extraction socket healing were evaluated in the WT and SostΔ26/Δ26 mice.

RESULTS

ONJ was not detected in the extraction socket of SostΔ26/Δ26 mice. Moreover, the incidence of ONJ was significantly lower in the SostΔ26/Δ26 mice treated with BP compared to that of the WT mice. Osteogenic proteins, osteocalcin, and runt-related transcription factor 2, were expressed in the bone surface in SostΔ26/Δ26 mice. Recombinant sclerostin inhibited gingival fibroblast migration. The wound healing rate of the extraction socket was faster in SostΔ26/Δ26 mice than in WT mice.

CONCLUSION

Sclerostin deficiency did not cause ONJ and reduced the risk of developing BP-induced ONJ. Enhanced bone formation and wound healing were observed in the tooth extraction socket. The use of romosozumab (anti-sclerostin antibody) has proven to be safe for surgical procedures of the jaw.

Extending the Therapeutic Potential: Romosozumab in Osteoporosis Management

Current therapeutic approaches for osteoporosis predominantly involve antiresorptive agents, but the emergence of bone anabolic therapy, such as romosozumab, presents a promising alternative. Romosozumab, a monoclonal antibody targeting sclerostin, exhibits both bone anabolic and antiresorptive effects, offering the potential to enhance bone mineral density and mitigate fracture risk. Evidence from several studies demonstrating the efficacy of romosozumab is now established in improving bone mineral density and reducing fracture rates in postmenopausal women and men. This review critically evaluates the role of romosozumab in osteoporosis management, emphasizing findings from real-world studies to facilitate its practical application in clinical settings. Adverse effects, comparative effectiveness with other osteoporotic agents, and challenges in sequential therapy are also discussed, providing insights for informed decision-making by physicians, particularly in the context of pre-treatment considerations. Additionally, the review examines global prescribing guidelines and highlights challenges associated with romosozumab utilization in special patient subgroups, aiming to optimize its clinical use.

Hydroxychloroquine and a low antiresorptive activity bisphosphonate conjugate prevent and reverse ovariectomy-induced bone loss in mice through dual antiresorptive and anabolic effects

Osteoporosis remains incurable. The most widely used antiresorptive agents, bisphosphonates (BPs), also inhibit bone formation, while the anabolic agent, teriparatide, does not inhibit bone resorption, and thus they have limited efficacy in preventing osteoporotic fractures and cause some side effects. Thus, there is an unmet need to develop dual antiresorptive and anabolic agents to prevent and treat osteoporosis. Hydroxychloroquine (HCQ), which is used to treat rheumatoid arthritis, prevents the lysosomal degradation of TNF receptor-associated factor 3 (TRAF3), an NF-κB adaptor protein that limits bone resorption and maintains bone formation. We attempted to covalently link HCQ to a hydroxyalklyl BP (HABP) with anticipated low antiresorptive activity, to target delivery of HCQ to bone to test if this targeting increases its efficacy to prevent TRAF3 degradation in the bone microenvironment and thus reduce bone resorption and increase bone formation, while reducing its systemic side effects. Unexpectedly, HABP-HCQ was found to exist as a salt in aqueous solution, composed of a protonated HCQ cation and a deprotonated HABP anion. Nevertheless, it inhibited osteoclastogenesis, stimulated osteoblast differentiation, and increased TRAF3 protein levels in vitro. HABP-HCQ significantly inhibited both osteoclast formation and bone marrow fibrosis in mice given multiple daily PTH injections. In contrast, HCQ inhibited marrow fibrosis, but not osteoclast formation, while the HABP alone inhibited osteoclast formation, but not fibrosis, in the mice. HABP-HCQ, but not HCQ, prevented trabecular bone loss following ovariectomy in mice and, importantly, increased bone volume in ovariectomized mice with established bone loss because HABP-HCQ increased bone formation and decreased bone resorption parameters simultaneously. In contrast, HCQ increased bone formation, but did not decrease bone resorption parameters, while HABP also restored the bone lost in ovariectomized mice, but it inhibited parameters of both bone resorption and formation. Our findings suggest that the combination of HABP and HCQ could have dual antiresorptive and anabolic effects to prevent and treat osteoporosis.

Evaluation of romosozumab's effects on bone marrow adiposity in postmenopausal osteoporotic women: results from the FRAME bone biopsy sub-study

Romosozumab, a humanized monoclonal antibody that binds and inhibits sclerostin, produces a marked increase in bone formation with a concomitant decreased bone resorption. This transient rise in bone formation in the first 2 months of treatment is mainly due to an increased modeling-based bone formation. This requires the recruitment and differentiation of osteoblasts, one possibility being a preferential switch in commitment of precursors to osteoblasts over adipocytes. The purpose of this study was to analyze the marrow adiposity in transiliac bone biopsies at months 2 or 12 from the FRAME biopsy sub-study in patients receiving romosozumab or placebo. The total adipocyte area, number, and density were measured on the total cancellous bone area. The size and shape at the individual adipocyte level were assessed including the mean adipocyte area, perimeter, min and max diameters, and aspect ratio. No significant difference in total adipocyte area, number, or density between placebo and romosozumab groups was observed at months 2 and 12, and no difference was observed between 2 and 12 months. After 2 or 12 months, romosozumab did not modify the size or shape of the adipocytes. No relationship between the adipocyte parameters and the dynamic parameters of bone formation could be evidenced. In conclusion, based on the analysis of a small number of biopsies, no effect of romosozumab on bone marrow adiposity of iliac crest was identified after 2 and 12 months suggesting that the modeling-based formation observed at month 2 was not due to a preferential commitment of the precursor to osteoblast over adipocyte cell lines but may result from a reactivation of bone lining cells and from a progenitor pool independent of the marrow adipocyte population.

Regional difference in the distribution of alkaline phosphatase, PHOSPHO1, and calcein labeling in the femoral metaphyseal trabeculae in parathyroid hormone-administered mice

OBJECTIVES

This study aimed to elucidate whether the administration of parathyroid hormone (PTH) results in remodeling- or modeling-based bone formation in different regions of the murine femora, and whether the PTH-driven bone formation would facilitate osteoblastic differentiation into osteocytes.

METHODS

Six-week-old male C57BL/6J mice were employed to examine the distribution of alkaline phosphatase (ALP), PHOSPHO1, podoplanin, and calcein labeling in two distinct long bone regions: the metaphyseal trabeculae close to the chondro-osseous junction (COJ) and those distant from the COJ in three mouse groups, a control group receiving a vehicle (sham group) and groups receiving hPTH (1-34) twice a day (PTH BID group) or four times a day (PTH QID group) for two weeks.

RESULTS

The sham group showed PHOSPHO1-reactive mature osteoblasts localized primarily at the COJ, whereas the PTH BID/QID groups exhibited extended lines of PHOSPHO1-reactive osteoblasts even in regions distant from the COJ. The PTH QID group displayed fragmented calcein labeling in trabeculae close to the COJ, whereas continuous labeling was observed in trabeculae distant from the COJ. Osteoblasts tended to express podoplanin and PHOSPHO1 independently in the close and distant regions of the sham group, while osteoblasts in the PTH-administered groups showed immunoreactivity of podoplanin and PHOSPHO1 together in the close and distant regions.

CONCLUSIONS

Administration of PTH may accelerate remodeling-based bone formation in regions close to the COJ while predominantly inducing modeling-based bone formation in distant regions. PTH appeared to simultaneously facilitate osteoblastic bone mineralization and differentiation into osteocytes in both remodeling- and modeling-based bone formation.

Treatment effects, adverse outcomes and cardiovascular safety of romosozumab - Existing worldwide data: A systematic review and meta-analysis

Background

Romosozumab is a novel monoclonal antibody that binds to sclerostin, and has dual effects of increasing bone formation and decreasing bone resorption, giving it a unique mechanism of action. The objective of this study was to perform a systematic review and meta-analysis based on existing worldwide data on treatment effects and safety of romosozumab in randomized controlled trials.

Methods

A systematic search was carried out on four databases including PubMed, Embase, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL). The keywords used for search was "(romosozumab) AND (osteoporosis OR safety)". Randomized controlled trial or post-hoc studies of the included randomized controlled trial which studied the effects and safety of romosozumab were included. The quality of selected studies was assessed with the Cochrane collaboration tool and the PEDro scale.

Results

20 studies were included for qualitative analysis. 14 studies were included for meta-analysis. In total, there were 13,507 (n = 13,507) participants with 637 men and 12,870 women from original cohorts. The overall mean difference was in favor of romosozumab treatment for lumbar spine (10.04 (95 % confidence interval (CI) = 7.51-12.57; p < 0.00001)), total hip (4.04 (95 % CI = 3.10-4.99; p < 0.00001)) and femoral neck bone mineral density (3.77 (95 % CI = 2.90-4.64; p < 0.00001)) at 12 months. There was significantly less likelihood of new vertebral fractures with romosozumab compared to control (odds ratio (OR) 0.42 (95 % CI = 0.20-0.89); p = 0.02) at 12 months of treatment. There was significantly less likelihood of new vertebral fracture at 24 months with 12 months of romosozumab followed by sequential treatment with anti-resorptive compared to control with only anti-resorptive agent use (OR 0.36 (95 % CI = 0.18-0.71); p = 0.003). There was no significant difference in serious adverse events and fatal adverse events with use of romosozumab compared with control in our meta-analyses. There were no significant differences in serious cardiovascular events in Asian population of romosozumab with control group with 12 months of romosozumab treatment followed by 24 months of anti-resorptive agent with OR 1.09 (95 % CI = 0.40-2.96; P = 0.86). There was no significant difference between romosozumab group and control group for the median time to radiographic healing. Our qualitative analysis on Quantitative Computed Tomography (QCT), Finite element analysis (FEA) and bone biopsy analyses demonstrated that romosozumab improved parameters and measures in these domains as well.

Conclusion

In conclusion, our study showed that romosozumab was an effective agent to treat osteoporosis with high quality evidence. There were no significant differences in the adverse events, serious adverse events, fatal adverse events identified. Further subgroup analysis of cardiovascular events and cardiovascular death in the total population showed no differences either.

The translational potential of this article

Given the results, romosozumab is an effective agent to treat patients with very-high risk of osteoporotic fractures.

The potential effect of romosozumab on perioperative management for instrumentation surgery

Background

Age-related changes in bone health increase the risk for complications in elderly patients undergoing orthopedic surgery. Osteoporosis is a key therapeutic target that needs to be addressed to ensure successful instrumentation surgery. The effectiveness of pharmacological interventions in orthopedic surgery, particularly the new drug romosozumab, is still unknown. We aim to evaluate the effect of 3-month romosozumab treatment on biomechanical parameters related to spinal instrumentation surgery, using the Quantitative Computed Tomography (QCT)-based Finite Element Method (FEM).

Methods

This open-labeled, prospective study included 81 patients aged 60 to 90 years, who met the osteoporosis criteria and were scheduled for either romosozumab or eldecalcitol treatment. Patients were assessed using blood samples, dual-energy absorptiometry (DXA), and QCT. Biomechanical parameters were evaluated using FEM at baseline and 3 months post-treatment. The primary endpoints were biomechanical parameters at 3 months, while secondary endpoints included changes in regional volumetric bone mineral density around the pedicle (P-vBMD) and vertebral body (V-vBMD).

Results

Romosozumab treatment led to significant gains in P-vBMD, and V-vBMD compared to eldecalcitol at 3 months. Notably, the romosozumab group showed greater improvements in all biomechanical parameters estimated by FEM at 3 months compared to the eldecalcitol group.

Conclusion

Romosozumab significantly increased the regional vBMD as well as biomechanical parameters, potentially offering clinical benefits in reducing post-operative complications in patients with osteoporosis undergoing orthopedic instrumentation surgery. This study highlights the novel advantages of romosozumab treatment and advocates further research on its effectiveness in perioperative management.

Bone union-promoting effect of romosozumab in an ovariectomized rat posterolateral lumbar fusion model

Spinal fixation surgery has been increasingly performed in patients with osteoporosis. Romosozumab, a drug that was introduced in Japan recently, is known to possibly promote bone healing. However, few studies have reported the therapeutic effects of romosozumab in clinical practice in Japan. Therefore, here, we investigated the effects of romosozumab dosage on bone fusion promotion using an ovariectomized rat spinal fusion model. Eight-week-old female Sprague-Dawley rats were matched by body weight and divided into three groups: 1.0 romosozumab (R) group (Evenity®, 25 mg/kg), 1/10R group (Evenity®, 2.5 mg/kg), and control (C) group (saline). Subcutaneous injections were administered twice a week for 8 weeks postoperatively. Computed tomography scans were performed every 2 weeks from the time of surgery till 8 weeks postoperatively. The mean fusion rates in terms of volume were significantly higher in the R groups [1/10R, 1.0R] than in the C group from 4 weeks postoperatively. The rate of increase was significantly higher in the 1.0R group from 4 weeks postoperatively and in the 1/10R group from 6 weeks postoperatively, than in the C group. The proportion of trabecular bone area was approximately 1.5 times higher in the R groups than in the C group. No significant differences were observed between the R groups. Our results suggest that romosozumab stimulates bone growth at the graft site, and similar effects were achieved at 1/10 of the standard dosage.

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 a transient early stimulation of modeling-based bone formation on cancellous and endocortical surfaces. Furthermore, 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, mo 12 (M12) and mo 2 (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 vs +1.5 μm; P = .012) and endocortical (+5.2 vs -1.7 μm; P = .02) surfaces; higher bone balance was due to lower final erosion depth (40.7 vs 43.7 μm; P = .05) on cancellous surfaces and higher completed wall thickness (50.8 vs 47.5 μm; P = .037) on endocortical surfaces. At M2, the final erosion depth was lower on the endocortical surfaces (42.7 vs 50.7 μm; P = .021) and was slightly lower on the cancellous surfaces (38.5 vs 44.6 μm; P = .11) with romosozumab vs placebo. Sector analysis of early endocortical formative sites revealed higher osteoid thickness (29.9 vs 19.2 μm; P = .005) and mineralized wall thickness (18.3 vs 11.9 μm; P = .004) with romosozumab vs placebo. These evolving bone packets may reflect the 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 versus parathyroid hormone receptor agonists: which osteoanabolic to choose and when?

Osteoanabolic agents are used as a first line treatment in patients at high fracture risk. The PTH receptor 1 (PTH1R) agonists teriparatide (TPTD) and abaloparatide (ABL) increase bone formation, bone mineral density (BMD), and bone strength by activating PTH receptors on osteoblasts. Romosozumab (ROMO), a humanized monoclonal antibody against sclerostin, dramatically but transiently stimulates bone formation and persistently reduces bone resorption. Osteoanabolic agents increase BMD and bone strength while being more effective than antiresorptives in reducing fracture risk in postmenopausal women. However, direct comparisons of the antifracture benefits of osteoanabolic therapies are limited. In a direct comparison of TPTD and ABL, the latter resulted in greater BMD increases at the hip. While no differences in vertebral or non-vertebral fracture risk were observed between the two drugs, ABL led to a greater reduction of major osteoporotic fractures. Adverse event profiles were similar between the two agents except for hypercalcemia, which occurred more often with TPTD. No direct comparisons of fracture risk reduction between ROMO and the PTH1R agonists exist. Individual studies have shown greater increases in BMD and bone strength with ROMO compared with TPTD in treatment-naive women and in women previously treated with bisphosphonates. Some safety aspects, such as a history of tumor precluding the use of PTH1R agonists, and a history of major cardiovascular events precluding the use of ROMO, should also be considered when choosing between these agents. Finally, convenience of administration, reimbursement by national health systems and length of clinical experience may influence patient choice.

Sclerostin blockade inhibits bone resorption through PDGF receptor signaling in osteoblast lineage cells

While sclerostin-neutralizing antibodies (Scl-Abs) transiently stimulate bone formation by activating Wnt signaling in osteoblast lineage cells, they exert sustained inhibition of bone resorption, suggesting an alternate signaling pathway by which Scl-Abs control osteoclast activity. Since sclerostin can activate platelet-derived growth factor receptors (PDGFRs) in osteoblast lineage cells in vitro and PDGFR signaling in these cells induces bone resorption through M-CSF secretion, we hypothesized that the prolonged anticatabolic effect of Scl-Abs could result from PDGFR inhibition. We show here that inhibition of PDGFR signaling in osteoblast lineage cells is sufficient and necessary to mediate prolonged Scl-Ab effects on M-CSF secretion and osteoclast activity in mice. Indeed, sclerostin coactivates PDGFRs independently of Wnt/β-catenin signaling inhibition, by forming a ternary complex with LRP6 and PDGFRs in preosteoblasts. In turn, Scl-Ab prevents sclerostin-mediated coactivation of PDGFR signaling and consequent M-CSF upregulation in preosteoblast cultures, thereby inhibiting osteoclast activity in preosteoblast/osteoclast coculture assays. These results provide a potential mechanism explaining the dissociation between anabolic and antiresorptive effects of long-term Scl-Ab.

Hydroxychloroquine and a low activity bisphosphonate conjugate prevent and reverse ovariectomy-induced bone loss in mice through dual antiresorptive and anabolic effects

Osteoporosis is incurable because there are no dual antiresorptive and anabolic therapeutic agents that can be administered long-term. The most widely used antiresorptive agents, bisphosphonates (BPs), also inhibit bone formation and thus have limited effect in preventing osteoporotic fracture. Hydroxychloroquine (HCQ), which is used to treat rheumatoid arthritis, prevents the lysosomal degradation of TNF receptor-associated factor 3 (TRAF3), an NF-κB adaptor protein that limits bone resorption and maintains bone formation. We attempted to covalently link HCQ to a hydroxyalklyl BP (HABP) with anticipated low antiresorptive activity, to target delivery of HCQ to bone to test if this targeting increases its efficacy to prevent TRAF3 degradation in the bone microenvironment and thus reduce bone resorption and increase bone formation, while reducing its systemic side effects. Unexpectedly, HABP-HCQ was found to exist as a salt in aqueous solution, composed of a protonated HCQ cation and a deprotonated HABP anion. Nevertheless, it inhibited osteoclastogenesis, stimulated osteoblast differentiation, and increased TRAF3 protein levels in vitro. HABP-HCQ significantly inhibited both osteoclast formation and bone marrow fibrosis in mice given multiple daily PTH injections. In contrast, HCQ inhibited fibrosis, but not osteoclast formation, while the HABP alone inhibited osteoclast formation, but not fibrosis, in the mice. HABP-HCQ, but not HCQ, prevented trabecular bone loss following ovariectomy in mice and, importantly, increased bone volume in ovariectomized mice with established bone loss because HABP-HCQ increased bone formation and decreased bone resorption parameters simultaneously. In contrast, HCQ increased bone formation, but did not decrease bone resorption parameters, while HABP also restored the bone lost in ovariectomized mice, but it inhibited parameters of both bone resorption and formation. Our findings suggest that the combination of HABP and HCQ could have dual antiresorptive and anabolic effects to prevent and treat osteoporosis.

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.

Eldecalcitol Induces Minimodeling-Based Bone Formation and Inhibits Sclerostin Synthesis Preferentially in the Epiphyses Rather than the Metaphyses of the Long Bones in Rats

This study aimed to examine minimodeling-based bone formation between the epiphyses and metaphyses of the long bones of eldecalcitol (ELD)-administered ovariectomized rats. Sixteen-week-old female rats were divided into four groups: sham-operated rats receiving vehicle (Sham group), ovariectomized (OVX) rats receiving vehicle (Vehicle group), or ELDs (30 or 90 ng/kg BW, respectively; ELD30 and ELD90 groups). ELD administration increased bone volume and trabecular thickness, reducing the number of osteoclasts in both the epiphyses and metaphyses of OVX rats. The Sham and Vehicle groups exhibited mainly remodeling-based bone formation in both regions. The epiphyses of the ELD groups showed a significantly higher frequency of minimodeling-based bone formation than remodeling-based bone formation. In contrast, the metaphyses exhibited significantly more minimodeling-based bone formation in the ELD90 group compared with the ELD30 group. However, there was no significant difference between minimodeling-based bone formation and remodeling-based bone formation in the ELD90 group. While the minimodeling-induced new bone contained few sclerostin-immunoreactive osteocytes, the underlying pre-existing bone harbored many. The percentage of sclerostin-positive osteocytes was significantly reduced in the minimodeling-induced bone in the epiphyses but not in the metaphyses of the ELD groups. Thus, it seems likely that ELD could induce minimodeling-based bone formation in the epiphyses rather than in the metaphyses, and that ELD-driven minimodeling may be associated with the inhibition of sclerostin synthesis.

A novel PDIA3/FTO/USP20 positive feedback regulatory loop induces osteogenic differentiation of preosteoblast in osteoporosis

Osteoporosis is a chronic skeletal disease and the major source of risk for fractures in aged people. It is urgent to investigate the mechanism regulating osteoporosis for developing potential treatment and prevention strategies. Osteogenic differentiation of preosteoblast enhances bone formation, which might be a promising strategy for treatment and prevention of osteoporosis. Protein disulfide isomerase family A, member 3 (PDIA3) could induce bone formation, yet the role of PDIA3 in osteogenic differentiation of preosteoblast remains unknown. In this study, m6 A RNA methylation was detected by methylated RNA immunoprecipitation (MeRIP), while mRNA stability was identified by RNA decay assay. Besides, protein-protein interaction and protein phosphorylation were determined using co-immunoprecipitation (Co-IP). Herein, results revealed that PDIA3 promoted osteogenic differentiation of preosteoblast MC3T3-E1. Besides, PDIA3 mRNA methylation was suppressed by FTO alpha-ketoglutarate dependent dioxygenase (FTO) as RNA methylation reduced PDIA3 mRNA stability during osteogenic differentiation of MC3T3-E1 cells. Moreover, ubiquitin specific peptidase 20 (USP20) improved FTO level through inhibiting FTO degradation while PDIA3 increased FTO level by enhancing USP20 phosphorylation during osteogenic differentiation of MC3T3-E1 cells, suggesting a positive feedback regulatory loop between PDIA3 and FTO. In summary, these findings indicated the mechanism of PDIA3 regulating osteogenic differentiation of preosteoblast and provided potential therapeutic targets for osteoporosis.

Network pharmacology analysis and experimental validation to explore the mechanism of kaempferol in the treatment of osteoporosis

Osteoporosis (OP) is a prevalent global disease characterized by bone mass loss and microstructural destruction, resulting in increased bone fragility and fracture susceptibility. Our study aims to investigate the potential of kaempferol in preventing and treating OP through a combination of network pharmacology and molecular experiments. Kaempferol and OP-related targets were retrieved from the public database. A protein-protein interaction (PPI) network of common targets was constructed using the STRING database and visualized with Cytoscape 3.9.1 software. Enrichment analyses for GO and KEGG of potential therapeutic targets were conducted using the Hiplot platform. Molecular docking was performed using Molecular operating environment (MOE) software, and cell experiments were conducted to validate the mechanism of kaempferol in treating OP. Network pharmacology analysis identified 54 overlapping targets between kaempferol and OP, with 10 core targets identified. The primarily enriched pathways included atherosclerosis-related signaling pathways, the AGE/RAGE signaling pathway, and the TNF signaling pathway. Molecular docking results indicated stable binding of kaempferol and two target proteins, AKT1 and MMP9. In vitro cell experiments demonstrated significant upregulation of AKT1 expression in MC3T3-E1 cells (p < 0.001) with kaempferol treatment, along with downregulation of MMP9 expression (p < 0.05) compared to the control group. This study predicted the core targets and pathways of kaempferol in OP treatment using network pharmacology, and validated these findings through in vitro experiments, suggesting a promising avenue for future clinical treatment of OP.

Inhibition of both sclerostin and DKK1 results in novel skull findings in the rat and non-human primate that is not observed with inhibition of sclerostin alone

Sclerostin is an extracellular inhibitor of canonical Wnt signaling that inhibits bone formation and stimulates bone resorption. Anti-sclerostin antibodies (Scl-Ab) have been developed as bone-building agents. DKK1, another extracellular inhibitor of the pathway, is upregulated in osteocytes in response to sclerostin inhibition. To further enhance bone-forming effects, a bispecific antibody inhibiting both sclerostin and DKK1 was created (AMG 147). In nonclinical safety studies, AMG 147 resulted in novel skull findings. In the rat, there was increased thickness of skull bones of neural crest origin due to increased subperiosteal compact lamellar and intramembranous woven bone. Externally, subperiosteal fibroblastic/osteoblastic stromal cell proliferation with woven bone and hemorrhage was also observed. Scl-Ab alone resulted in increased skull thickness in the rat, like AMG 147, but without the stromal cell proliferation/woven bone formation. In contrast to embryonic flat bone development, intramembranous bone formed similar to plexiform bone. In the monkey, AMG 147 resulted in macroscopic skull thickening due to a diffuse increase in appositional lamellar bone and increased intramembranous bone on both periosteal surfaces of all skull bones. These data demonstrate that dual inhibition of sclerostin and DDK1 results in unique effects on the skull not observed with sclerostin inhibition alone.

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.

The Sequential Therapy in Osteoporosis

Background

Osteoporosis management often involves a sequential treatment approach to optimize patient outcomes and minimize fracture risks. This strategy is tailored to individual patient characteristics, treatment responses, and fracture risk profiles.

Methods

A thorough literature review was systematically executed using prominent databases, including PubMed and EMBASE. The primary aim was to identify original articles and clinical trials evaluating the effectiveness of sequential therapy with anti-osteoporosis drugs, focusing on the period from 1995 to 2023. The analysis encompassed an in-depth examination of osteoporosis drugs, delineating their mechanisms of action, side effects, and current trends as elucidated in the literature.

Results and Discussion

Our study yielded noteworthy insights into the optimal sequencing of pharmacologic agents for the long-term treatment of patients necessitating multiple drugs. Notably, the achievement of optimal improvements in bone mass is observed when commencing treatment with an anabolic medication, followed by the subsequent utilization of an antiresorptive drug. This stands in contrast to initiating therapy with a bisphosphonate, which may potentially diminish outcomes in the post-anabolic intervention period. Furthermore, it has been discerned that caution should be exercised against transitioning from denosumab to PTH homologs due to the adverse effects of heightened bone turnover and sustained weakening of bone structure. Despite the absence of fracture data substantiating the implementation of integrated anabolic/antiresorptive pharmacotherapy, the incorporation of denosumab and teriparatide presents a potential avenue worthy of consideration for individuals at a heightened vulnerability to fragility fractures.

Conclusions

A judiciously implemented sequential treatment strategy in osteoporosis offers a flexible and tailored approach to address diverse clinical scenarios, optimizing fracture prevention and patient outcomes.

Romosozumab is associated with greater trabecular bone score improvement compared to denosumab in postmenopausal osteoporosis

In this study, romosozumab demonstrated significantly greater improvement in trabecular bone score compared to denosumab therapy in postmenopausal women previously treated with antiresorptive agents. Notably, in patients previously treated with anti-resorptive agents, treatment with romosozumab resulted in similar increases in trabecular bone score compared to that of drug-naïve patients.

PURPOSE

Romosozumab significantly increases bone mineral density (BMD) and rapidly reduces fracture risk. Whether romosozumab can improve the spinal trabecular bone score (TBS) as a bone quality indicator merits further investigation.

METHODS

Data for postmenopausal women starting romosozumab or denosumab treatment at Severance Hospital, Korea, were analyzed. Romosozumab and denosumab groups were 1:1 matched using propensity scores, considering relevant covariates. Good responders were defined as those with TBS improvement of 5.8% or greater.

RESULTS

Overall, 174 patients (romosozumab, n = 87; denosumab, n = 87) were analyzed. Matched groups did not differ in age (64 years), weight, height, previous fracture (38%), lumbar spine or femoral neck BMD (T-score, -3.4 and -2.6, respectively), or prior bisphosphonate or selective estrogen receptor modulator (SERM) exposure (50%). The romosozumab group exhibited a greater increase in lumbar spine BMD (15.2% vs. 6.9%, p < 0.001) and TBS (3.7% vs. 1.7%, p = 0.013) than the denosumab group. In patients transitioning from bisphosphonate or SERM, romosozumab users showed greater improvement in TBS compared to denosumab users (3.9% versus 0.8%, P = 0.006); the drug-naive group showed no significant difference (3.6% versus 2.7%, P = 0.472). The romosozumab group had a higher proportion of good responders than the denosumab group (33.3% vs. 18.4%, p = 0.024). Romosozumab therapy for 12 months resulted in 3.8-fold higher odds of a good response in TBS than denosumab after covariate adjustment (adjusted odds ratio 3.85, p = 0.002).

CONCLUSION

Romosozumab could improve bone mass and bone quality, measured by TBS, in postmenopausal osteoporosis, particularly as a subsequent regimen in patients previously taking anti-resorptive agents.

Buds of new bone formation within the Femoral Head of Hip Fracture Patients Coincide with Zones of Low Osteocyte Sclerostin

Romosozumab treatment reduces the rate of hip fractures and increases hip bone density, increasing bone formation by inhibiting sclerostin protein. We studied the normal pattern of bone formation and osteocyte expression in the human proximal femur because it is relevant to both antisclerostin treatment effects and fracture. Having visualized and quantified buds of new bone formation in trabeculae, we hypothesized that they would coincide with areas of (a) higher mechanical stress and (b) low sclerostin expression by osteocytes. In patients with hip fracture, we visualized each bud of active modeling-based formation (forming minimodeling structure [FMiS]) in trabecular cores taken from different parts of the femoral head. Trabecular bone structure was also measured with high-resolution imaging. More buds of new bone formation (by volume) were present in the higher stress superomedial zone (FMiS density, N.FMiS/T.Ar) than lower stress superolateral (p < 0.05), and inferomedial (p < 0.001) regions. There were fewer sclerostin expressing osteocytes close to or within FMiS. FMiS density correlated with greater amount, thickness, number, and connectivity of trabeculae (bone volume BV/TV, r = 0.65, p < 0.0001; bone surface BS/TV, r = 0.47, p < 0.01; trabecular thickness Tb.Th, r = 0.55, p < 0.001; trabecular number Tb.N, r = 0.47, p < 0.01; and connectivity density Conn.D, r = 0.40, p < 0.05) and lower trabecular separation (Tb.Sp, r = -0.56, p < 0.001). These results demonstrate modeling-based bone formation in femoral trabeculae from patients with hip fracture as a potential therapeutic target to enhance bone structure. © 2023 American Society for Bone and Mineral Research (ASBMR).

Targeting Kindlin-2 in adipocytes increases bone mass through inhibiting FAS/PPARγ/FABP4 signaling in mice

Osteoporosis (OP) is a systemic skeletal disease that primarily affects the elderly population, which greatly increases the risk of fractures. Here we report that Kindlin-2 expression in adipose tissue increases during aging and high-fat diet fed and is accompanied by decreased bone mass. Kindlin-2 specific deletion (K2KO) controlled by Adipoq-Cre mice or adipose tissue-targeting AAV (AAV-Rec2-CasRx-sgK2) significantly increases bone mass. Mechanistically, Kindlin-2 promotes peroxisome proliferator-activated receptor gamma (PPARγ) activation and downstream fatty acid binding protein 4 (FABP4) expression through stabilizing fatty acid synthase (FAS), and increased FABP4 inhibits insulin expression and decreases bone mass. Kindlin-2 inhibition results in accelerated FAS degradation, decreased PPARγ activation and FABP4 expression, and therefore increased insulin expression and bone mass. Interestingly, we find that FABP4 is increased while insulin is decreased in serum of OP patients. Increased FABP4 expression through PPARγ activation by rosiglitazone reverses the high bone mass phenotype of K2KO mice. Inhibition of FAS by C75 phenocopies the high bone mass phenotype of K2KO mice. Collectively, our study establishes a novel Kindlin-2/FAS/PPARγ/FABP4/insulin axis in adipose tissue modulating bone mass and strongly indicates that FAS and Kindlin-2 are new potential targets and C75 or AAV-Rec2-CasRx-sgK2 treatment are potential strategies for OP treatment.

Romosozumab in osteoporosis: yesterday, today and tomorrow

Osteoporosis is a systemic bone disease characterized by low bone mass, microarchitectural deterioration, increased bone fragility, and fracture susceptibility. It commonly occurs in older people, especially postmenopausal women. As global ageing increases, osteoporosis has become a global burden. There are a number of medications available for the treatment of osteoporosis, categorized as anabolic and anti-resorptive. Unfortunately, there is no drugs which have dual influence on bone, while all drugs have limitations and adverse events. Some serious adverse events include jaw osteonecrosis and atypical femoral fracture. Recently, a novel medication has appeared that challenges this pattern. Romosozumab is a novel drug monoclonal antibody to sclerostin encoded by the SOST gene. It has been used in Japan since 2019 and has achieved promising results in treating osteoporosis. However, it is also accompanied by some controversy. While it promotes rapid bone growth, it may cause serious adverse events such as cardiovascular diseases. There has been scepticism about the drug since its inception. Therefore, the present review comprehensively covered romosozumab from its inception to its clinical application, from animal studies to human studies, and from safety to cost. We hope to provide a better understanding of romosozumab for its clinical application.

Update on the clinical use of trabecular bone score (TBS) in the management of osteoporosis: results of an expert group meeting organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), and the International Osteoporosis Foundation (IOF) under the auspices of WHO Collaborating Center for Epidemiology of Musculoskeletal Health and Aging

PURPOSE

Trabecular bone score (TBS) is a grey-level textural measurement acquired from dual-energy X-ray absorptiometry lumbar spine images and is a validated index of bone microarchitecture. In 2015, a Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) published a review of the TBS literature, concluding that TBS predicts hip and major osteoporotic fracture, at least partly independent of bone mineral density (BMD) and clinical risk factors. It was also concluded that TBS is potentially amenable to change as a result of pharmacological therapy. Further evidence on the utility of TBS has since accumulated in both primary and secondary osteoporosis, and the introduction of FRAX and BMD T-score adjustment for TBS has accelerated adoption. This position paper therefore presents a review of the updated scientific literature and provides expert consensus statements and corresponding operational guidelines for the use of TBS.

METHODS

An Expert Working Group was convened by the ESCEO and a systematic review of the evidence undertaken, with defined search strategies for four key topics with respect to the potential use of TBS: (1) fracture prediction in men and women; (2) initiating and monitoring treatment in postmenopausal osteoporosis; (3) fracture prediction in secondary osteoporosis; and (4) treatment monitoring in secondary osteoporosis. Statements to guide the clinical use of TBS were derived from the review and graded by consensus using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

A total of 96 articles were reviewed and included data on the use of TBS for fracture prediction in men and women, from over 20 countries. The updated evidence shows that TBS enhances fracture risk prediction in both primary and secondary osteoporosis, and can, when taken with BMD and clinical risk factors, inform treatment initiation and the choice of antiosteoporosis treatment. Evidence also indicates that TBS provides useful adjunctive information in monitoring treatment with long-term denosumab and anabolic agents. All expert consensus statements were voted as strongly recommended.

CONCLUSION

The addition of TBS assessment to FRAX and/or BMD enhances fracture risk prediction in primary and secondary osteoporosis, adding useful information for treatment decision-making and monitoring. The expert consensus statements provided in this paper can be used to guide the integration of TBS in clinical practice for the assessment and management of osteoporosis. An example of an operational approach is provided in the appendix. This position paper presents an up-to-date review of the evidence base, synthesised through expert consensus statements, which informs the implementation of Trabecular Bone Score in clinical practice.

Dual Inhibition of the Wnt Inhibitors DKK1 and Sclerostin Promotes Fracture Healing and Increases the Density and Strength of Uninjured Bone: An Experimental Study in Nonhuman Primates

BACKGROUND

Fracture repair involves the reactivation of developmental signaling cascades, including Wnt signaling that stimulates bone formation and bone regeneration. Rodent data indicate that dual inhibition of the Wnt signaling antagonists sclerostin and Dickkopf-1 (DKK1) increases callus bone volume and strength while increasing bone mass systemically.

METHODS

We evaluated the effects of 16 weeks of subcutaneously administered carrier solution (vehicle, VEH), anti-sclerostin antibody (Scl-Ab), anti-DKK1 antibody (DKK1-Ab), or Scl-Ab plus DKK1-Ab combination therapy (COMBO) on ulnar osteotomy healing in nonhuman primates (cynomolgus monkeys; 20 to 22 per group).

RESULTS

Scl-Ab and COMBO therapy increased systemic markers of bone formation versus VEH, with COMBO leading to synergistic increases versus Scl-Ab or DKK1-Ab monotherapies. The COMBO and Scl-Ab groups showed reduced serum markers of bone resorption versus VEH. The COMBO and DKK1-Ab groups exhibited greater callus bone mineral density (BMD), torsional stiffness, and torsional rigidity versus VEH. Lumbar vertebrae from the Scl-Ab and COMBO groups showed greater BMD and bone formation rate versus VEH, and the femoral mid-diaphysis of the Scl-Ab and COMBO groups showed greater periosteal and endocortical bone formation rates versus VEH.

CONCLUSIONS

DKK1-Ab increased BMD and strength at the ulnar osteotomy site, Scl-Ab increased bone formation and BMD at uninjured skeletal sites, and Scl-Ab plus DKK1-Ab combination therapy induced all of these effects, in some cases to a greater degree versus 1 or both monotherapies. These results in nonhuman primates suggest that DKK1 preferentially regulates bone healing while sclerostin preferentially regulates systemic bone mass.

CLINICAL RELEVANCE

Combination therapy with antibodies against sclerostin and DKK1 may offer a promising therapeutic strategy for both fracture treatment and fracture prevention.

Anti-resorptive therapy in the osteometabolic patient affected by periodontitis. A joint position paper of the Italian Society of Orthopaedics and Traumatology (SIOT) and the Italian Society of Periodontology and Implantology (SIdP)

This joint report from the Italian Society of Orthopaedics and Traumatology (SIOT) and the Italian Society of Periodontology and Implantology (SIdP) aims for a consensus around the scientific rationale and clinical strategy for the management of osteoporotic patients affected by periodontitis who are undergoing anti-resorptive (AR) therapy to manage the risk of the occurrence of a medication-related osteonecrosis of the jaws (MRONJ). Osteoporosis and periodontitis are chronic diseases with a high prevalence in aging patients, and they share some of the same pathogenetic mechanisms based upon inflammation. Available evidence shows the relationship among osteoporosis, AR agents, periodontitis and implant therapy in relation to the incidence of MRONJ. Uncontrolled periodontitis may lead to tooth loss and to the need to replace teeth with dental implants. Tooth extraction and surgical dental procedures are recognized as the main risk factors for developing MRONJ in individuals taking AR therapy for osteometabolic conditions. Although the incidence of MRONJ in osteometabolic patients taking AR therapy may be as low as 0.9%, the increasing prevalence of osteoporosis and the high prevalence of periodontitis suggest that this potential complication should not be overlooked. Good clinical practice (GCP) guidelines are proposed that aim at a more integrated approach (prescriber, dentist, periodontist and dental hygienist) in the management of periodontitis patients undergoing AR therapy for osteometabolic disorders to reduce the risk of MRONJ. Dental professional and prescribers should educate patients regarding the potential risk associated with the long-term use of AR therapy and oral health behavior.

Meta-analysis of the effects of denosumab and romosozumab on bone mineral density and turnover markers in patients with osteoporosis

Purpose

To assess the alterations in bone mineral density and bone turnover marker concentrations following the administration of denosumab and romosozumab therapies in patients with osteoporosis.

Methods

PubMed was searched for studies published until January 28, 2023, that investigated the clinical efficacy and bone turnover marker changes of denosumab and romosozumab in the treatment of osteoporosis, with a minimum follow-up of 3 months in each study. Studies were screened, and data on changes in bone mineral density (BMD), P1NP, and TRACP-5b levels after treatment were extracted and included in the analysis.

Results

Six studies were analyzed. At 3 months after treatment, the romosozumab group showed greater changes in lumbar BMD and bone turnover markers. BMD of total hip and femoral neck was relatively delayed. Beginning at 6 to 12 months, romosozumab showed greater changes in bone mineral density and markers of bone turnover.

Conclusion

Both romosozumab and denosumab have antiosteoporotic effects, with greater effects on BMD and bone turnover markers observed within 12 months of romosozumab treatment.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero, identifier CRD42023395034.

Measuring Drug Therapy Effect on Osteoporotic Fracture Risk by Trabecular Bone Lacunarity: The LOTO Study

An MRI method providing one parameter (TBLβ: trabecular-bone-lacunarity-parameter-β) that is sensitive to trabecular bone architecture (TBA) changes with aging and osteoporosis is under study as a new tool in the early diagnosis of bone fragility fracture. A cross-sectional and prospective observational study (LOTO: Lacunarity Of Trabecular bone in Osteoporosis) on over-50s women, at risk for bone fragility fracture, was designed to validate the method. From the baseline data, we observed that in women with prevalent vertebral fractures (VF+), TBA was differently characterized by TBLβ when osteoporosis treatment is considered. Here we verify the potential of TBLβ as an index of osteoporosis treatment efficacy. Untreated (N = 156) and treated (N = 123) women were considered to assess differences in TBLβ related to osteoporosis treatment. Prevalent VFs were found in 31% of subjects, 63% of which were under osteoporosis medications. The results show that TBLβ discriminates between VF+ and VF- patients (p = 0.004). This result is mostly stressed in untreated subjects. Treatment, drug therapy in particular (89% Bisphosphonates), significantly counteracts the difference between VF+ and VF- within and between groups: TBLβ values in treated patients are comparable to untreated VF- and statistically higher than untreated VF+ (p = 0.014) ones. These results highlight the potential role of TBLβ as an index of treatment efficacy.

GIP reduces osteoclast activity and improves osteoblast survival in primary human bone cells

OBJECTIVE

Drugs targeting the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) are emerging as treatments for type-2 diabetes and obesity. GIP acutely decreases serum markers of bone resorption and transiently increases bone formation markers in short-term clinical investigations. However, it is unknown whether GIP acts directly on bone cells to mediate these effects. Using a GIPR-specific antagonist, we aimed to assess whether GIP acts directly on primary human osteoclasts and osteoblasts.

METHODS

Osteoclasts were differentiated from human CD14+ monocytes and osteoblasts from human bone. GIPR expression was determined using RNA-seq in primary human osteoclasts and in situ hybridization in human femoral bone. Osteoclastic resorptive activity was assessed using microscopy. GIPR signaling pathways in osteoclasts and osteoblasts were assessed using LANCE cAMP and AlphaLISA phosphorylation assays, intracellular calcium imaging and confocal microscopy. The bioenergetic profile of osteoclasts was evaluated using Seahorse XF-96.

RESULTS

GIPR is robustly expressed in mature human osteoclasts. GIP inhibits osteoclastogenesis, delays bone resorption, and increases osteoclast apoptosis by acting upon multiple signaling pathways (Src, cAMP, Akt, p38, Akt, NFκB) to impair nuclear translocation of nuclear factor of activated T cells-1 (NFATc1) and nuclear factor-κB (NFκB). Osteoblasts also expressed GIPR, and GIP improved osteoblast survival. Decreased bone resorption and improved osteoblast survival were also observed after GIP treatment of osteoclast-osteoblast co-cultures. Antagonizing GIPR with GIP(3-30)NH2 abolished the effects of GIP on osteoclasts and osteoblasts.

CONCLUSIONS

GIP inhibits bone resorption and improves survival of human osteoblasts, indicating that drugs targeting GIPR may impair bone resorption, whilst preserving bone formation.

Romosozumab for the treatment of postmenopausal women at high risk of fracture

INTRODUCTION

Romosozumab is a monoclonal antibody that binds to sclerostin (an inhibitor of the Wingless-related integration site (Wnt) signaling pathway). It is a new osteoanabolic drug that simultaneously increases bone formation and decreases bone resorption. It has recently been approved by the US and EU authorities in postmenopausal women with at high risk of fractures.

AREAS COVERED

The literature on romosozumab in preclinical and in phase II and III clinical studies has been reviewed about the effect on bone, bone markers, and fracture reduction and its safety.

EXPERT OPINION

Compared to antiresorptive agents, its unique mechanism of action results in a quicker and greater increase in bone mineral density, it repairs and restores trabecular and cortical bone microarchitecture, and reduces fracture risk more rapidly and more effectively than alendronate, with persisting effects for at least two years after transition to antiresorptive agents. This finding has introduced the concept that, in patients at very high risk of fractures, the optimal sequence of treatment is to start with an osteoanabolic agent, followed by a potent AR drug. Recent national and international guidelines recommend the use of romosozumab as an initial treatment in patients at very high fracture risk without a history of stroke or myocardial infarction.

A high-throughput biomimetic bone-on-a-chip platform with artificial intelligence-assisted image analysis for osteoporosis drug testing

Although numerous organ-on-a-chips have been developed, bone-on-a-chip platforms have rarely been reported because of the high complexity of the bone microenvironment. With an increase in the elderly population, a high-risk group for bone-related diseases such as osteoporosis, it is essential to develop a precise bone-mimicking model for efficient drug screening and accurate evaluation in preclinical studies. Here, we developed a high-throughput biomimetic bone-on-a-chip platform combined with an artificial intelligence (AI)-based image analysis system. To recapitulate the key aspects of natural bone microenvironment, mouse osteocytes (IDG-SW3) and osteoblasts (MC3T3-E1) were cocultured within the osteoblast-derived decellularized extracellular matrix (OB-dECM) built in a well plate-based three-dimensional gel unit. This platform spatiotemporally and configurationally mimics the characteristics of the structural bone unit, known as the osteon. Combinations of native and bioactive ingredients obtained from the OB-dECM and coculture of two types of bone cells synergistically enhanced osteogenic functions such as osteocyte differentiation and osteoblast maturation. This platform provides a uniform and transparent imaging window that facilitates the observation of cell-cell interactions and features high-throughput bone units in a well plate that is compatible with a high-content screening system, enabling fast and easy drug tests. The drug efficacy of anti-SOST antibody, which is a newly developed osteoporosis drug for bone formation, was tested via β-catenin translocation analysis, and the performance of the platform was evaluated using AI-based deep learning analysis. This platform could be a cutting-edge translational tool for bone-related diseases and an efficient alternative to bone models for the development of promising drugs.

Advancement in the Treatment of Osteoporosis and the Effects on Bone Healing

Osteoporosis (OP) is a major global health concern, with aging being one of the most important risk factors. Osteoarthritis (OA) is also an age-related disorder. Patients with OP and/or OA may be treated surgically for fractures or when their quality of life is impaired. Poor bone quality due to OP can seriously complicate the stability of a bone fixation construct and/or surgical fracture treatment. This review summarizes the current knowledge on the pathophysiology of normal and osteoporotic bone healing, the effect of a bone fracture on bone turnover markers, the diagnosis of a low bone mineral density (BMD) before surgical intervention, and the effect of available anti-osteoporosis treatment. Interventions that improve bone health may enhance the probability of favorable surgical outcomes. Fracture healing and the treatment of atypical femoral fractures are also discussed.