Nonclinical cardiovascular safety evaluation of romosozumab, an inhibitor of sclerostin for the treatment of osteoporosis in postmenopausal women at high risk of fracture

Romosozumab for the treatment of osteoporosis - a systematic review

INTRODUCTION

Romosozumab, a new treatment of osteoporosis, is a monoclonal antibody that targets sclerostin and thereby exhibits a dual mechanism of action by stimulating bone formation and inhibiting bone resorption. This systematic review aims to assess the clinical efficacy and safety of romosozumab for treatment of primary and secondary osteoporosis.

METHODS

A comprehensive literature search was conducted in October 2023 across multiple databases including Embase, PubMed and Cochrane Library. Randomized controlled trials (RCTs) and observational studies evaluating the impact of romosozumab on BMD, bone turnover markers (BTM), fracture outcomes, and its safety profile were included. Data extraction and quality assessment were performed independently by two reviewers in accordance with PRISMA guidelines.

RESULTS

A total of 36 articles met the inclusion criteria. Romosozumab significantly increased BMD at the lumbar spine, total hip, and femoral neck compared to placebo and active comparators in patients with primary osteoporosis. Sequential therapy with romosozumab followed by antiresorptives maintained or further increased BMD and reduced fracture risk. Romosozumab was generally well tolerated, however, an imbalance in cardiovascular adverse event was observed in one large clinical trial. Observational studies supported these findings. Specific subgroups of patients with secondary osteoporosis were assessed, demonstrating overall positive outcomes with romosozumab treatment.

CONCLUSION

Romosozumab effectively increases BMD and reduces fracture risk, particularly when used as initial therapy in high fracture-risk patients. Sequential therapy with subsequent antiresorptive treatment optimizes long-term benefits. While generally well-tolerated, its cardiovascular safety profile requires further long-term studies to ensure its safety in clinical practice. Additional studies are needed to confirm efficacy and safety in patients with secondary 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.

Recommendations for the optimal use of bone forming agents in osteoporosis

Bone forming agents, also known as anabolic therapies, are essential in managing osteoporosis, particularly for patients at very high-risk of fractures. Identifying candidates who will benefit the most from these treatments is crucial. For example, this group might include individuals with severe osteoporosis, multiple vertebral fractures, a recent fragility fracture or those unresponsive to antiresorptive treatments. Definitions of patients with a very high fracture risk vary across nations, are often based on fracture history, bone mineral density (BMD), and/or fracture risk calculated by FRAX® or other algorithms. However, for very high-risk patients, anabolic agents such as teriparatide, abaloparatide, or romosozumab are commonly recommended as first-line therapies due to their ability to stimulate new bone formation and improve bone microarchitecture, offering significant benefits in rapid fracture reduction over antiresorptive therapies. The cost-effectiveness of these agents is a critical consideration for decision-makers. Despite their higher costs, their effectiveness in significantly reducing fracture risk and improving quality of life can justify the investment, especially when long-term savings from reduced fracture rates and associated healthcare costs are considered. Additionally, after completing a course of anabolic therapy, transitioning to antiresorptive agents like bisphosphonates or denosumab is crucial to maintain the gains in bone density and minimize subsequent fracture risks. This sequential treatment approach ensures sustained protection and optimal resource utilization. In summary, the effective use of bone forming agents in osteoporosis requires a comprehensive strategy that includes accurate patient identification, consideration of cost-effectiveness, and implementation of appropriate sequential treatments, ultimately maximizing patient outcomes and healthcare efficiency.

Sclerostin and Cardiovascular Disease

PURPOSE OF REVIEW

The role of wnt signalling in atherogenesis raises the possibility that the wnt inhibitor, sclerostin, provides a natural defence to this process, and that anti-sclerostin antibodies might increase the risk of atherosclerosis and associated conditions such as CVD. This article aims to triangulate evidence concerning possible adverse effects of sclerostin inhibition on CVD risk.

RECENT FINDINGS

Randomised controlled trials of treatment with the anti-sclerostin antibody, romosozumab, have yielded conflicting evidence with respect to possible adverse effects of sclerostin inhibition on CVD risk. To further examine the causal relationship between sclerostin inhibition and CVD risk, three Mendelian randomisation (MR) studies have examined effects of sclerostin lowering on CVD outcomes, using common genetic variants in the SOST gene which produces sclerostin, to mimic effects of a randomised trial. Concordant findings were seen in two studies, comprising an effect of sclerostin lowering on increased risk of MI and type II diabetes mellitus. One study also suggested that sclerostin lowering increases coronary artery calcification. Triangulation of evidence from different sources provides some suggestion that sclerostin lowering increases MI risk, supporting the need for CVD risk assessment when considering treatment with romosozumab.

Trends in Management of Osteoporosis Following Primary Vertebral Compression Fracture

Purpose

Osteoporosis affects more than 200 million individuals worldwide and predisposes to vertebral compression fractures (VCFs). Given undertreatment of fragility fractures, including VCFs, we investigate current anti-osteoporotic medication prescribing trends.

Methods

Patients 50 and older with a diagnosis of primary closed thoracolumbar VCF between 2004 and 2019 were identified from the Clinformatics® Data Mart database. Multivariate analysis was performed for demographic and clinical treatment and outcome variables.

Results

Of 143 081 patients with primary VCFs, 16 780 (11.7%) were started on anti-osteoporotic medication within a year; 126 301 (88.3%) patients were not started on medication. The medication cohort was older (75.4 ± 9.3 vs 74.0 ± 12.3 years, P < .001), had higher Elixhauser Comorbidity Index scores (4.7 ± 6.2 vs 4.3 ± 6.7, P < .001), was more likely to be female (81.1% vs 64.4%, P < .001), and was more likely to have a formal osteoporosis diagnosis (47.8% vs 32.9%) than the group that did not receive medication. Alendronate (63.4%) and calcitonin (27.8%) were the most commonly initiated medications. The proportion of individuals receiving anti-osteoporotic medication within the year following VCF peaked in 2008 (15.2%), then declined until 2012 with a modest increase afterward.

Conclusions

Osteoporosis remains undertreated after low-energy VCFs. New anti-osteoporotic medication classes have been approved in recent years. Bisphosphonates remain the most prescribed class. Increasing recognition and treatment of osteoporosis is paramount to decreasing the risk of subsequent fractures.

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.

Targeting loop3 of sclerostin preserves its cardiovascular protective action and promotes bone formation

Sclerostin negatively regulates bone formation by antagonizing Wnt signalling. An antibody targeting sclerostin for the treatment of postmenopausal osteoporosis was approved by the U.S. Food and Drug Administration, with a boxed warning for cardiovascular risk. Here we demonstrate that sclerostin participates in protecting cardiovascular system and inhibiting bone formation via different loops. Loop3 deficiency by genetic truncation could maintain sclerostin’s protective effect on the cardiovascular system while attenuating its inhibitory effect on bone formation. We identify an aptamer, named aptscl56, which specifically targets sclerostin loop3 and use a modified aptscl56 version, called Apc001PE, as specific in vivo pharmacologic tool to validate the above effect of loop3. Apc001PE has no effect on aortic aneurysm and atherosclerotic development in ApoE−/− mice and hSOSTki.ApoE−/− mice with angiotensin II infusion. Apc001PE can promote bone formation in hSOSTki mice and ovariectomy-induced osteoporotic rats. In summary, sclerostin loop3 cannot participate in protecting the cardiovascular system, but participates in inhibiting bone formation.

Role of Sclerostin in Cardiovascular Disease

Sclerostin is most recognized for its role in controlling bone formation but is also expressed in the heart, aorta, coronary, and peripheral arteries. This review summarizes research on sclerostin's role in cardiovascular disease. Rodent studies have found sclerostin to be expressed at sites of arterial calcification. In contrast, aortic sclerostin was reported to be downregulated in a mouse model of abdominal aortic aneurysm, and transgenic upregulation or administration of sclerostin was found to prevent abdominal aortic aneurysm and atherosclerosis formation. Sclerostin deficiency was reported to stimulate cardiac rupture in one rodent model. In humans, 7 of 11 studies reported a significant association between high serum sclerostin and high carotid intima media thickness. Ten of 15 studies reported a significant association between high serum sclerostin and severe arterial calcification. Twelve of 14 studies reported a significant association between high serum sclerostin and high arterial stiffness or atherosclerosis severity. Four of 9 studies reported a significant association between high serum sclerostin and high risk of cardiovascular events. A meta-analysis of randomized controlled trials suggested that administration of the sclerostin blocking antibody romosozumab did not significantly increase the risk of major adverse cardiovascular events (risk ratio, 1.14 [95% CI, 0.83-1.57]; P=0.54) or cardiovascular death (risk ratio, 0.92 [95% CI, 0.53-1.59]; P=0.71). Human genetic studies reported variants predisposing to low arterial sclerostin expression were associated with a high risk of cardiovascular events. Overall, past research suggests a cardiovascular protective role of sclerostin but findings have been inconsistent, possibly due to variations in study design, the unique populations and models studied, and the heterogeneous methods used.

Identification of potential biomarkers of vascular calcification using bioinformatics analysis and validation in vivo

Background

Vascular calcification (VC) is the most widespread pathological change in diseases of the vascular system. However, we know poorly about the molecular mechanisms and effective therapeutic approaches of VC.

Methods

The VC dataset, GSE146638, was downloaded from the Gene Expression Omnibus (GEO) database. Using the edgeR package to screen Differentially expressed genes (DEGs). Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to find pathways affecting VC. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed on the DEGs. Meanwhile, using the String database and Cytoscape software to construct protein-protein interaction (PPI) networks and identify hub genes with the highest module scores. Correlation analysis was performed for hub genes. Receiver operating characteristic (ROC) curves, expression level analysis, GSEA, and subcellular localization were performed for each hub gene. Expression of hub genes in normal and calcified vascular tissues was verified by quantitative reverse transcription PCR (RT-qPCR) and immunohistochemistry (IHC) experiments. The hub gene-related miRNA-mRNA and TF-mRNA networks were constructed and functionally enriched for analysis. Finally, the DGIdb database was utilized to search for alternative drugs targeting VC hub genes.

Results

By comparing the genes with normal vessels, there were 64 DEGs in mildly calcified vessels and 650 DEGs in severely calcified vessels. Spp1, Sost, Col1a1, Fn1, and Ibsp were central in the progression of the entire VC by the MCODE plug-in. These hub genes are primarily enriched in ossification, extracellular matrix, and ECM-receptor interactions. Expression level results showed that Spp1, Sost, Ibsp, and Fn1 were significantly highly expressed in VC, and Col1a1 was incredibly low. RT-qPCR and IHC validation results were consistent with bioinformatic analysis. We found multiple pathways of hub genes acting in VC and identified 16 targeting drugs.

Conclusions

This study perfected the molecular regulatory mechanism of VC. Our results indicated that Spp1, Sost, Col1a1, Fn1, and Ibsp could be potential novel biomarkers for VC and promising therapeutic targets.

Drug therapy for osteoporosis in older adults

The goal of osteoporosis management is to prevent fractures. Several pharmacological agents are available to lower fracture risk, either by reducing bone resorption or by stimulating bone formation. Bisphosphonates are the most widely used anti-resorptives, reducing bone turnover markers to low premenopausal concentrations and reducing fracture rates (vertebral by 50-70%, non-vertebral by 20-30%, and hip by ~40%). Bisphosphonates bind avidly to bone mineral and have an offset of effect measured in months to years. Long term, continuous use of oral bisphosphonates is usually interspersed with drug holidays of 1-2 years, to minimise the risk of atypical femoral fractures. Denosumab is a monoclonal antibody against RANKL that potently inhibits osteoclast development and activity. Denosumab is administered by subcutaneous injection every 6 months. Anti-fracture effects of denosumab are similar to those of the bisphosphonates, but there is a pronounced loss of anti-resorptive effect from 7 months after the last injection, which can result in clusters of rebound vertebral fractures. Two classes of anabolic drugs are now available to stimulate bone formation. Teriparatide and abaloparatide both target the parathyroid hormone-1 receptor, and are given by daily subcutaneous injection for up to 2 years. Romosozumab is an anti-sclerostin monoclonal antibody that stimulates bone formation and inhibits resorption. Romosozumab is given as monthly subcutaneous injections for 1 year. Head-to-head studies suggest that anabolic agents have greater anti-fracture efficacy and produce larger increases in bone density than anti-resorptive drugs. The effects of anabolic agents are transient, so transition to anti-resorptive drugs is required. The optimal strategy for cycling anabolics, anti-resorptives, and off-treatment periods remains to be determined.

Cardiovascular Safety of Anti-Sclerostin Therapy in Chronic Kidney Disease

The significance of sclerostin for bone and cardiovascular health in patients with chronic kidney disease (CKD) is complex and incompletely understood. Experimental evidence suggests that anti-sclerostin therapy shows diminished efficacy on bone in the setting of CKD. Limited clinical evidence suggests that the osteoanabolic and anti-resorptive activity is attenuated, but hypocalcemia is more prevalent in patients with advanced CKD (eGFR < 30 mL/min) treated with anti-sclerostin (romosozumab) therapy as compared to patients without kidney disease. Furthermore, sclerostin is prominently expressed in uremic arteries. Whether the inhibition of sclerostin has adverse effects on cardiovascular health in CKD is currently unknown. This review summarizes the current understanding of the physiology and pathophysiology of sclerostin in CKD, with a focus on the cardiovascular safety of anti-sclerostin therapy in patients with or without CKD.

Automatic Quantification of Atherosclerosis in Contrast-Enhanced MicroCT Scans of Mouse Aortas Ex Vivo

Objective

While microCT evaluation of atherosclerotic lesions in mice has been formally validated, existing image processing methods remain undisclosed. We aimed to develop and validate a reproducible image processing workflow based on phosphotungstic acid-enhanced microCT scans for the volumetric quantification of atherosclerotic lesions in entire mouse aortas. Approach and Results. 42 WT and 42 apolipoprotein E knockout mouse aortas were scanned. The walls, lumen, and plaque objects were segmented using dual-threshold algorithms. Aortic and plaque volumes were computed by voxel counting and lesion surface by triangulation. The results were validated against manual and histological evaluations. Knockout mice had a significant increase in plaque volume compared to wild types with a plaque to aorta volume ratio of 0.3%, 2.8%, and 9.8% at weeks 13, 18, and 26, respectively. Automatic segmentation correlated with manual (r ² ≥ 0.89; p < .001) and histological evaluations (r ² > 0.96; p < .001).

Conclusions

The semiautomatic workflow enabled rapid quantification of atherosclerotic plaques in mice with minimal manual work.

Osteoanabolic therapy for osteoporosis in women

Therapy to activate bone formation is required to reverse and restore the damaged bone architecture found in women with postmenopausal osteoporosis. The osteoanabolic drugs include teriparatide, which has been available for several years, and abaloparatide and romosozumab, novel osteoanabolic drugs that have become available more recently. By stimulating bone formation, these drugs produce greater increases in bone mass and bone strength, and they do so more quickly compared to the commonly used anti-remodeling (also called antiresorptive) drugs such as bisphosphonates. In head-to-head trials, teriparatide and romosozumab reduce fracture risk more effectively than do oral bisphosphonates in women with osteoporosis and high fracture risk. Osteoanabolic drugs have little role in the prevention of bone loss during early menopause, but they have an important place in the treatment of women at very high risk of fracture or who remain at high fracture risk after a course of bisphosphonate therapy. Primarily because of the high cost of the drugs, these therapies are initiated by specialists rather than primary-care physicians in most countries. This review will present the evidence for efficacy and safety of these drugs so that clinicians may discern their appropriate use when caring for postmenopausal women with osteoporosis.

Sclerostin Downregulation Globally by Naturally Occurring Genetic Variants, or Locally in Atherosclerotic Plaques, Does Not Associate With Cardiovascular Events in Humans

Inhibition of sclerostin increases bone formation and decreases bone resorption, leading to increased bone mass, bone mineral density, and bone strength and reduced fracture risk. In a clinical study of the sclerostin antibody romosozumab versus alendronate in postmenopausal women (ARCH), an imbalance in adjudicated serious cardiovascular (CV) adverse events driven by an increase in myocardial infarction (MI) and stroke was observed. To explore whether there was a potential mechanistic plausibility that sclerostin expression, or its inhibition, in atherosclerotic (AS) plaques may have contributed to this imbalance, sclerostin was immunostained in human plaques to determine whether it was detected in regions relevant to plaque stability in 94 carotid and 50 femoral AS plaques surgically collected from older female patients (mean age 69.6 ± 10.4 years). Sclerostin staining was absent in most plaques (67%), and when detected, it was of reduced intensity compared with normal aorta and was located in deeper regions of the plaque/wall but was not observed in areas considered relevant to plaque stability (fibrous cap and endothelium). Additionally, genetic variants associated with lifelong reduced sclerostin expression were explored for associations with phenotypes including those related to bone physiology and CV risk factors/events in a population-based phenomewide association study (PheWAS). Natural genetic modulation of sclerostin by variants with a significant positive effect on bone physiology showed no association with lifetime risk of MI or stroke. These data do not support a causal association between the presence of sclerostin, or its inhibition, in the vasculature and increased risk of serious cardiovascular events. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Cardiovascular Safety and Sclerostin Inhibition

Sclerostin, which is primarily produced by the osteocytes, inhibits the canonical Wnt pathway and thereby the osteoblasts and stimulates RANKL release by the osteocytes and thereby osteoclast recruitment. Inhibition of sclerostin therefore causes stimulation of bone formation and inhibition of resorption. In clinical trials, romosozumab, an antibody against sclerostin, increases bone mineral density and reduces the risk of fractures compared with placebo and alendronate. The cardiovascular safety of romosozumab was adjudicated in 2 large clinical osteoporosis trials in postmenopausal women. Compared with placebo, the incidence of cardiovascular events was similar in the 2 treatment groups. Compared with alendronate, the incidence of serious cardiovascular events was higher in women treated with romosozumab. The incidence of serious cardiovascular adverse events was low and post hoc analyses should therefore be interpreted with caution; however, the relative risk seemed unaffected by preexisting cardiovascular disease or risk factors. Sclerostin is expressed in the vasculature, predominantly in vascular smooth muscle cells in the media. However, preclinical and genetic studies have not demonstrated any increased cardiovascular risk with continuously low sclerostin levels or inhibition of sclerostin. Furthermore, no potential mechanisms for such an effect have been identified. In conclusion, while there is no preclinical or genetic evidence of a harmful effect of sclerostin inhibition on cardiovascular safety, the evidence from the large clinical trials in postmenopausal women is conflicting. Romosozumab should therefore be used for the treatment of postmenopausal women with osteoporosis at high risk of fracture after careful consideration of the cardiovascular risk and the balance between benefits and risks.

Cardiovascular Safety Profile of Romosozumab: A Pharmacovigilance Analysis of the US Food and Drug Administration Adverse Event Reporting System (FAERS)

Background: Cardiovascular safety concerns for major cardiovascular events (MACE) were raised during the clinical trials of romosozumab. We aimed to evaluate the cardiovascular safety profile of romosozumab in a large pharmacovigilance database. Methods: All cases reported between January 2019 and December 2020 where romosozumab was reported were extracted from the Food and Drug Administration Adverse Event Reporting System (FAERS). The outcome of interest was MACE (myocardial infarction (MI), stroke, or cardiovascular death). A disproportionality analysis was conducted by estimating the reporting odds ratios (RORs) and 95% confidence intervals. Disproportionality analyses were stratified by sex and reporting region (US, Japan, other). Results: Of the 1995 eligible cases with romosozumab, the majority (N = 1188; 59.5%) originated from Japan. Overall, 206 suspected MACE reports were identified, of which the majority (n = 164; 13.8%) were from Japan, and 41 (5.2%) were from the United States (US). Among Japanese reports, patients were older and more frequently male than reports from the US. Similarly, cases with a reported MACE were older and had higher reports of cardioprotective drugs than those without cardiovascular events. Elevated reports for MACE (ROR 4.07, 95% CI: 2.39–6.93) was identified overall, which was primarily driven by the significant disproportionality measures in the Japanese reports. Conclusions: The current pharmacovigilance study identified a potential signal for elevated MACE, particularly in Japan. The results support the current safety warnings from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) to avoid use in high-risk patients.

Core battery safety pharmacology testing - An assessment of its utility in early drug development

Requirements for safety pharmacology testing have been in place since the issue of initial regulatory guidance over 20 years ago. An evaluation of such testing, supporting first clinical entry of 105 small molecule drug candidates over the last decade, showed that a "core battery" of in vitro electrophysiological (hERG), conscious non-rodent telemetry cardiovascular, rodent central nervous system (CNS) (modified Irwin's or functional observational battery [FOB] test) and respiratory function (plethysmography) studies was performed. Routine use of the latter 2 studies appears to have limited utility, with only 21% and 28% of studies, respectively, giving findings of which none were identified as of obvious concern to moving the affected drugs into the clinic. The use of a stand-alone hERG assay does not appear to be particular sensitive in predicting proarrythmic risk as a tool by itself. Telemetry study testing had utility especially for identifying effects on QTc interval (about 10% of studies), resulting on some occasions in a lower clinical starting dose and/or increased awareness for potential effects on the cardiovascular system in the Phase I study. Overall, this investigation provides information supporting an overhaul of the current "box ticking" core battery approach used for safety pharmacology testing. However, in order to achieve a more focused examination to investigate potential undesirable pharmacodynamic effects of a new candidate drug and also support 3Rs (Replacement, Reduction and Refinement) thinking in performing unnecessary studies, there will not only need to be a sea change by drug developers but also a change in current regulatory guidance.

Anabolic Agents for Postmenopausal Osteoporosis: How Do You Choose?

PURPOSE OF REVIEW

There are now three anabolic agents available for the treatment of postmenopausal women at high risk for fracture. The purpose of this review is to supply a rationale to aid in determining which agent should be used in which clinical settings.

RECENT FINDINGS

Studies over the last decade have shown that anabolic agents produce faster and larger effects against fracture than antiresorptive agents. Furthermore, trials evaluating anabolic antiresorptive treatment sequences have shown that anabolic first treatment strategies produce the greatest benefits to bone density, particularly in the hip region. However, there are no head-to-head evaluations of the three anabolic therapies with fracture outcomes or bone density, and these studies are not likely to occur. How to decide which agent to use at which time in a woman's life is unknown. We review the most significant clinical trials of anabolic agents which have assessed fracture, areal or volumetric bone density, microarchitecture, and/or bone strength, as well as information gleaned from histomorphometry studies to provide a rationale for consideration of one agent vs another in various clinical settings. There is no definitive answer to this question; all three agents increase bone strength and reduce fracture risk rapidly. Since the postmenopausal lifespan could be as long as 40-50 years, it is likely that very high-risk women will utilize different anabolic agents at different points in their lives.

Postmenopausal osteoporosis coexisting with other metabolic diseases: Treatment considerations

In postmenopausal women, osteoporosis may coexist with other metabolic diseases, including, but not limited to, obesity, diabetes, nonalcoholic fatty liver disease (NAFLD), dyslipidemia and cardiovascular disease (CVD). This association may lie beyond simple coincidence owing to high prevalence of all these diseases, especially in the aging population, as common pathogenetic mechanisms between them and osteoporosis may exist. In this context, anti-osteoporotic medications may affect the pathogenesis of some of these metabolic diseases; this is an important consideration when selecting the most appropriate medication for osteoporotic patients with coexistent metabolic diseases. Conversely, some current or emerging medications for metabolic diseases adversely affect bone metabolism and, if possible, should be avoided in women with postmenopausal osteoporosis. The main aim of this review is to summarize the evidence on anti-osteoporotic treatment in postmenopausal women with concomitant metabolic diseases, i.e. obesity, diabetes, NAFLD, dyslipidemia and CVD. The secondary aim is to present data on the effect of current or emerging medication for metabolic diseases on bone metabolism of postmenopausal women. Deeper understanding of the underlying links between osteoporosis and metabolic diseases may have clinical implications. However, mechanistic studies are needed to elucidate the potential pathophysiological links, as well as clinical trials in women with postmenopausal osteoporosis coexisting with specific metabolic diseases; these may guide clinical practice in the future for the selection of the best anti-osteoporotic medication for each patient with specific metabolic diseases.

Romosozumab: A Review in Postmenopausal Osteoporosis

Romosozumab (Evenity^®), a humanized monoclonal antibody, promotes bone formation and inhibits bone resorption by inhibiting sclerostin, a protein involved in the regulation of bone formation. Subcutaneous romosozumab is approved in several countries, including those of the EU for treating severe osteoporosis as well as in the USA for osteoporosis in postmenopausal women at high risk of fracture. In pivotal phase III trials (FRAME and ARCH), 12 months' once-monthly romosozumab 210 mg significantly reduced vertebral and clinical fracture risk versus placebo and oral alendronate in postmenopausal women with osteoporosis. After patients transitioned from romosozumab to 12-24 months of subcutaneous denosumab or oral alendronate, fracture risks were significantly improved versus placebo-to-denosumab and alendronate-only treatment. In these trials and a phase IIIb trial, romosozumab significantly increased bone mineral density (BMD) relative to placebo, alendronate and subcutaneous teriparatide at 12 months, with these benefits maintained 12-24 months after patients transitioned from romosozumab to alendronate or denosumab in pivotal trials. Romosozumab had a generally manageable tolerability profile. While further clinical experience is needed to more definitively establish its efficacy and safety, including its CV safety, romosozumab extends the treatment options in postmenopausal women with osteoporosis who have a high risk of fracture and in those who have failed or are intolerant to other available osteoporosis therapy.

Advances in Osteoporotic Bone Tissue Engineering

The increase in osteoporotic fracture worldwide is urging bone tissue engineering research to find new, improved solutions both for the biomaterials used in designing bone scaffolds and the anti-osteoporotic agents capable of promoting bone regeneration. This review aims to report on the latest advances in biomaterials by discussing the types of biomaterials and their properties, with a special emphasis on polymer-ceramic composites. The use of hydroxyapatite in combination with natural/synthetic polymers can take advantage of each of their components properties and has a great potential in bone tissue engineering, in general. A comparison between the benefits and potential limitations of different scaffold fabrication methods lead to a raised awareness of the challenges research face in dealing with osteoporotic fracture. Advances in 3D printing techniques are providing the ways to manufacture improved, complex, and specialized 3D scaffolds, capable of delivering therapeutic factors directly at the osteoporotic skeletal defect site with predefined rate which is essential in order to optimize the osteointegration/healing rate. Among these factors, strontium has the potential to increase osseointegration, osteogenesis, and healing rate. Strontium ranelate as well as other biological active agents are known to be effective in treating osteoporosis due to both anti-resorptive and anabolic properties but has adverse effects that can be reduced/avoided by local release from biomaterials. In this manner, incorporation of these agents in polymer-ceramic composites bone scaffolds can have significant clinical applications for the recovery of fractured osteoporotic bones limiting or removing the risks associated with systemic administration.

Shuxuetong injection simultaneously ameliorates dexamethasone-driven vascular calcification and osteoporosis

Osteoporosis (OP) and vascular calcification (VC) share a number of common risk factors, pathophysiological mechanisms and etiology, which are known as bone-vascular axis. The present study aimed to investigate the effects of Shuxuetong (SXT) injection on VC and osteoporosis. A rat model of VC and osteoporosis was induced by dexamethasone (DEX; 1 mg/kg/day for 4 weeks, intramuscularly). Simultaneously, 0.6 ml/kg/day SXT was intraperitoneally injected. Compared with control rats, DEX induced significantly more VC and OP, as determined by increased calcium deposition and alkaline phosphatase activity in the aorta, disturbed structure, decreased levels of cortical bone thickness and trabecular bone area, and increased apoptosis in the bone. SXT injection ameliorated DEX-induced VC and osteoporosis; furthermore, the osteoblastic differentiation of vascular smooth muscle cells and the activation of endoplasmic reticulum stress in the DEX group was also prevented by SXT injection. Compared with control rats, protein expression levels of sclerostin, a crucial crosslink of the bone-vascular axis, were significantly increased in the aorta and bone of rats with DEX, which was also attenuated by SXT injection. Thus, the present study suggested that SXT injection could ameliorate both VC and OP, and may be mediated by the regulation of sclerostin. The present study may provide the basis a novel strategy for the prevention and treatment of VC and OP, which emerge as side-effects of glucocorticoids.

Sclerostin and Osteocalcin: Candidate Bone-Produced Hormones

In addition to its structural role, the skeleton serves as an endocrine organ that controls mineral metabolism and energy homeostasis. Three major cell types in bone - osteoblasts, osteoclasts, and osteocytes - dynamically form and maintain bone and secrete factors with systemic activity. Osteocalcin, an osteoblast-derived factor initially described as a matrix protein that regulates bone mineralization, has been suggested to be an osteoblast-derived endocrine hormone that regulates multiple target organs including pancreas, liver, muscle, adipose, testes, and the central and peripheral nervous system. Sclerostin is predominantly produced by osteocytes, and is best known as a paracrine-acting regulator of WNT signaling and activity of osteoblasts and osteoclasts on bone surfaces. In addition to this important paracrine role for sclerostin within bone, sclerostin protein has been noted to act at a distance to regulate adipocytes, energy homeostasis, and mineral metabolism in the kidney. In this article, we aim to bring together evidence supporting an endocrine function for sclerostin and osteocalcin, and discuss recent controversies regarding the proposed role of osteocalcin outside of bone. We summarize the current state of knowledge on animal models and human physiology related to the multiple functions of these bone-derived factors. Finally, we highlight areas in which future research is expected to yield additional insights into the biology of osteocalcin and sclerostin.

Glucocorticoid-Induced Osteoporosis: The Potential Role of Romosozumab

Glucocorticoid (GC)-induced osteoporosis (GIOP) is a major problem in patients with rheumatic diseases. The deleterious effect of GC on bone turnover is rapid and dose-dependent, with a predilection on the trabecular bone, resulting in vertebral fractures. Early recognition and prompt treatment of GIOP helps prevent bone loss and reduce fractures. There are pitfalls in current assessment tools for GIOP by dual-energy X-ray absorptiometry (DXA) and fracture risk assessment tool (FRAX) estimation formula. In this review, we evaluate different assessment methods for GIOP and summarize current therapies of GIOP, including the antiresorptive and anabolic agents. The potential role of newer anti-osteoporosis agent romosozumab, an anti-sclerostin monoclonal antibody, is also discussed.

Anti-Sclerostin Antibodies in Osteoporosis and Other Bone Diseases

The Wnt pathway is a key element of bone remodeling; its activation stimulates bone formation and inhibits bone resorption. The discovery of sclerostin, a natural antagonist of the Wnt pathway, promoted the development of romosozumab, a human monoclonal antibody directed against sclerostin, as well as other anti-sclerostin antibodies. Phase 3 studies have shown the efficacy of romosozumab in the prevention of fractures in postmenopausal women, against placebo but also against alendronate or teriparatide and this treatment also allows bone mineral density (BMD) increase in men. Romosozumab induces the uncoupling of bone remodeling, leading to both an increase in bone formation and a decrease in bone resorption during the first months of treatment. The effect is attenuated over time and reversible when stopped but transition with anti-resorbing agents allows the maintenance or reinforcement of BMD improvements. Some concerns were raised about cardiovascular events. Therefore, romosozumab was recently approved in several countries for the treatment of severe osteoporosis in postmenopausal women with high fracture risk and without a history of heart attack, myocardial infarction or stroke. This review aims to outline the role of sclerostin, the efficacy and safety of anti-sclerostin therapies and in particular romosozumab and their place in therapeutic strategies against osteoporosis or other bone diseases.