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

Cardiovascular safety of osteoanabolic agents

PURPOSE

Several osteoanabolic agents have been developed to build new bone more efficiently than anti-resorptive drugs. Among them, romosozumab, an anti-sclerostin antibody, is a potent pharmacological tool to prevent fractures in osteoporosis patients. The efficacy of romosozumab in preventing osteoporotic fractures is robust. However, there remains a concern about increased cardiovascular (CV) adverse events related to romosozumab. Available data have been reviewed to address this concern.

METHODS

Published articles on romosozumab of which pivotal randomized controlled trials (RCTs), meta-analyses of RCTs, pharmacovigilance investigations, and retrospective observational clinical studies using real-world data were collected through PubMed and other available tools.

RESULTS

Meta-analyses of RCTs of romosozumab compared to placebo and other anti-osteoporosis drugs have left room for controversy in the CV safety of romosozumab. Investigations of the real-world data also provide no conclusive evidence in this issue.

CONCLUSION

We need more robust evidence to establish an appropriate and reasonable guide to prescribe romosozumab in our clinical practice.

Comparative effectiveness and cardiovascular safety of romosozumab versus teriparatide in patients with osteoporosis: a population-based cohort study

This study compared the effectiveness and cardiovascular safety of romosozumab and teriparatide. The main finding was that there were no significant differences between the two drugs in fracture prevention and risk of major adverse cardiac events. This suggests that romosozumab and teriparatide are comparable options for treating osteoporosis.

PURPOSE

This study aimed to determine the preventive effects of romosozumab versus teriparatide on fractures and the risk of cardiovascular events in patients initiating these drugs.

METHODS

We conducted an active comparator, a new user cohort design, with confounding controlled by inverse probability of treatment weighting using a Japanese administrative claims database (March 2019 to October 2022). This cohort study included 49,104 patients aged 50 years or older who initiated romosozumab (n = 16,125) or teriparatide (n = 32,979) for osteoporosis. The study exposure was the initiation of romosozumab or teriparatide. Effectiveness outcomes were nonvertebral fracture and hip fracture. The safety outcome was major adverse cardiac events (MACE). Follow-up period was 365 days.

RESULTS

The weighted incidence rate difference (IRD) for nonvertebral fracture between romosozumab versus teriparatide was -0.08 (95% confidence interval [CI], -0.34 to 0.17) events per 100 person-years (weighted hazard ratio [HR], 0.95 [95% CI, 0.81 to 1.12]); weighted IRD for hip fracture was 0.00 (95% CI, -0.16 to 0.16) events per 100 person-years (weighted HR, 0.99 [95% CI, 0.76 to 1.29]); and weighted IRD for MACE was -0.06 (95% CI, -0.20 to 0.09) events per 100 person-years (weighted HR, 0.90 [95% CI, 0.68 to 1.19]).

CONCLUSION

In patients with osteoporosis, there was no significant difference in the prevention of nonvertebral fracture and hip fracture between romosozumab and teriparatide. In addition, the risk of MACE was comparable between the two drugs.

Effect of genetically predicted sclerostin on cardiovascular biomarkers, risk factors, and disease outcomes

Sclerostin inhibitors protect against osteoporotic fractures, but their cardiovascular safety remains unclear. We conducted a cis-Mendelian randomisation analysis to estimate the causal effect of sclerostin levels on cardiovascular risk factors. We meta-analysed three GWAS of sclerostin levels including 49,568 Europeans and selected 2 SNPs to be used as instruments. We included heel bone mineral density and hip fracture risk as positive control outcomes. Public GWAS and UK Biobank patient-level data were used for the study outcomes, which include cardiovascular events, risk factors, and biomarkers. Lower sclerostin levels were associated with higher bone mineral density and 85% reduction in hip fracture risk. However, genetically predicted lower sclerostin levels led to 25-85% excess coronary artery disease risk, 40% to 60% increased risk of type 2 diabetes, and worse cardiovascular biomarkers values, including higher triglycerides, and decreased HDL cholesterol levels. Results also suggest a potential (but borderline) association with increased risk of myocardial infarction. Our study provides genetic evidence of a causal relationship between reduced levels of sclerostin and improved bone health and fracture protection, but increased risk of cardiovascular events and risk factors.

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.

Efficacy of Osteoporosis Medications in Patients with Type 2 Diabetes

PURPOSE OF THE REVIEW

The purpose of the review is to summarise the current scientific evidence on the efficacy of osteoporosis medications in patients with type 2 diabetes.

RECENT FINDINGS

Type 2 diabetes (T2D) is a growing global epidemic. The highest prevalence is observed in the elderly, the same population affected by osteoporosis. Despite normal or even increased bone mineral density and low bone turnover, T2D is associated with an increased risk of fractures in most skeletal sites. These findings raised concerns over the efficacy of anti-osteoporosis drugs in this population. There is no randomised controlled trial designed specifically for people with T2D. However, observational studies and post-hoc analyses of randomised controlled trials have provided valuable insights into the effects of various anti-osteoporosis treatments in this population. Overall, most anti-osteoporosis drugs seem to have similar efficacy and safety profiles for people with and without type 2 diabetes. However, continued research and long-term safety data are needed to optimise treatment strategies and improve bone health outcomes in this population. The current evidence suggests that most anti-osteoporosis drugs exhibit comparable efficacy in people with and without T2D.

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.

Lowering of Circulating Sclerostin May Increase Risk of Atherosclerosis and Its Risk Factors: Evidence From a Genome-Wide Association Meta-Analysis Followed by Mendelian Randomization

OBJECTIVE

In this study, we aimed to establish the causal effects of lowering sclerostin, target of the antiosteoporosis drug romosozumab, on atherosclerosis and its risk factors.

METHODS

A genome-wide association study meta-analysis was performed of circulating sclerostin levels in 33,961 European individuals. Mendelian randomization (MR) was used to predict the causal effects of sclerostin lowering on 15 atherosclerosis-related diseases and risk factors.

RESULTS

We found that 18 conditionally independent variants were associated with circulating sclerostin. Of these, 1 cis signal in SOST and 3 trans signals in B4GALNT3, RIN3, and SERPINA1 regions showed directionally opposite signals for sclerostin levels and estimated bone mineral density. Variants with these 4 regions were selected as genetic instruments. MR using 5 correlated cis-SNPs suggested that lower sclerostin increased the risk of type 2 diabetes mellitus (DM) (odds ratio [OR] 1.32 [95% confidence interval (95% CI) 1.03-1.69]) and myocardial infarction (MI) (OR 1.35 [95% CI 1.01-1.79]); sclerostin lowering was also suggested to increase the extent of coronary artery calcification (CAC) (β = 0.24 [95% CI 0.02-0.45]). MR using both cis and trans instruments suggested that lower sclerostin increased hypertension risk (OR 1.09 [95% CI 1.04-1.15]), but otherwise had attenuated effects.

CONCLUSION

This study provides genetic evidence to suggest that lower levels of sclerostin may increase the risk of hypertension, type 2 DM, MI, and the extent of CAC. Taken together, these findings underscore the requirement for strategies to mitigate potential adverse effects of romosozumab treatment on atherosclerosis and its related risk factors.

B4GALNT3 regulates glycosylation of sclerostin and bone mass

BACKGROUND

Global sclerostin inhibition reduces fracture risk efficiently but has been associated with cardiovascular side effects. The strongest genetic signal for circulating sclerostin is in the B4GALNT3 gene region, but the causal gene is unknown. B4GALNT3 expresses the enzyme beta-1,4-N-acetylgalactosaminyltransferase 3 that transfers N-acetylgalactosamine onto N-acetylglucosaminebeta-benzyl on protein epitopes (LDN-glycosylation).

METHODS

To determine if B4GALNT3 is the causal gene, B4galnt3^-/- mice were developed and serum levels of total sclerostin and LDN-glycosylated sclerostin were analysed and mechanistic studies were performed in osteoblast-like cells. Mendelian randomization was used to determine causal associations.

FINDINGS

B4galnt3^-/- mice had higher circulating sclerostin levels, establishing B4GALNT3 as a causal gene for circulating sclerostin levels, and lower bone mass. However, serum levels of LDN-glycosylated sclerostin were lower in B4galnt3^-/- mice. B4galnt3 and Sost were co-expressed in osteoblast-lineage cells. Overexpression of B4GALNT3 increased while silencing of B4GALNT3 decreased the levels of LDN-glycosylated sclerostin in osteoblast-like cells. Mendelian randomization demonstrated that higher circulating sclerostin levels, genetically predicted by variants in the B4GALNT3 gene, were causally associated with lower BMD and higher risk of fractures but not with higher risk of myocardial infarction or stroke. Glucocorticoid treatment reduced B4galnt3 expression in bone and increased circulating sclerostin levels and this may contribute to the observed glucocorticoid-induced bone loss.

INTERPRETATION

B4GALNT3 is a key factor for bone physiology via regulation of LDN-glycosylation of sclerostin. We propose that B4GALNT3-mediated LDN-glycosylation of sclerostin may be a bone-specific osteoporosis target, separating the anti-fracture effect of global sclerostin inhibition, from indicated cardiovascular side effects.

FUNDING

Found in acknowledgements.

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.

Circulating Sclerostin Levels Are Positively Related to Coronary Artery Disease Severity and Related Risk Factors

Romosozumab is a newly available treatment for osteoporosis acting by sclerostin inhibition. Its cardiovascular safety has been questioned after finding excess cardiovascular disease (CVD)-related events in a pivotal phase 3 trial. Previous studies of relationships between circulating sclerostin levels and CVD and associated risk factors have yielded conflicting findings, likely reflecting small numbers and selected patient groups. We aimed to characterize relationships between sclerostin and CVD and related risk factors in more detail by examining these in two large cohorts, Ludwigshafen Risk and Cardiovascular Health study (LURIC; 34% female, mean age 63.0 years) and Avon Longitudinal Study of Parents and Children study (ALSPAC) mothers (mean age 48.1 years). Together these provided 5069 participants with complete data. Relationships between sclerostin and CVD risk factors were meta-analyzed, adjusted for age, sex (LURIC), body mass index, smoking, social deprivation, and ethnicity (ALSPAC). Higher sclerostin levels were associated with higher risk of diabetes mellitus (DM) (odds ratio [OR] = 1.25; 95% confidence interval [CI] 1.12, 1.37), risk of elevated fasting glucose (OR 1.15; CI 1.04, 1.26), and triglyceride levels (β 0.03; CI 0.00, 0.06). Conversely, higher sclerostin was associated with lower estimated glomerular filtration rate (eGFR) (β -0.20; CI -0.38, -0.02), HDL cholesterol (β -0.05; CI -0.10, -0.01), and apolipoprotein A-I (β -0.05; CI -0.08, -0.02) (difference in mean SD per SD increase in sclerostin, with 95% CI). In LURIC, higher sclerostin was associated with an increased risk of death from cardiac disease during follow-up (hazard ratio [HR] = 1.13; 1.03, 1.23) and with severity of coronary artery disease on angiogram as reflected by Friesinger score (0.05; 0.01, 0.09). Associations with cardiac mortality and coronary artery severity were partially attenuated after adjustment for risk factors potentially related to sclerostin, namely LDL and HDL cholesterol, log triglycerides, DM, hypertension, eGFR, and apolipoprotein A-I. Contrary to trial evidence suggesting sclerostin inhibition leads to an increased risk of CVD, sclerostin levels appear to be positively associated with coronary artery disease severity and mortality, partly explained by a relationship between higher sclerostin levels and major CVD risk factors. © 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 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.

Romosozumab and cardiovascular safety in Japan

Romosozumab is a potent pharmacological tool to prevent fractures in osteoporosis patients, and its mechanism of action is distinct from any other drugs. The efficacy of romosozumab to prevent osteoporotic fractures is remarkable. However, there remains a concern of increased cardiovascular adverse events. Further relevant investigations are essential to understand whether romosozumab is actually involved in the development of cardiovascular events or not. We need more robust evidence to establish an appropriate and reasonable guide to prescribe romosozumab in our clinical practice.