Romosozumab - Promising or Practice Changing?

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.

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.

Drug discovery of sclerostin inhibitors

Sclerostin, a protein secreted from osteocytes, negatively regulates the WNT signaling pathway by binding to the LRP5/6 co-receptors and further inhibits bone formation and promotes bone resorption. Sclerostin contributes to musculoskeletal system-related diseases, making it a promising therapeutic target for the treatment of WNT-related bone diseases. Additionally, emerging evidence indicates that sclerostin contributes to the development of cancers, obesity, and diabetes, suggesting that it may be a promising therapeutic target for these diseases. Notably, cardiovascular diseases are related to the protective role of sclerostin. In this review, we summarize three distinct types of inhibitors targeting sclerostin, monoclonal antibodies, aptamers, and small-molecule inhibitors, from which monoclonal antibodies have been developed. As the first-in-class sclerostin inhibitor approved by the U.S. FDA, the monoclonal antibody romosozumab has demonstrated excellent effectiveness in the treatment of postmenopausal osteoporosis; however, it conferred high cardiovascular risk in clinical trials. Furthermore, romosozumab could only be administered by injection, which may cause compliance issues for patients who prefer oral therapy. Considering these above safety and compliance concerns, we therefore present relevant discussion and offer perspectives on the development of next-generation sclerostin inhibitors by following several ways, such as concomitant medication, artificial intelligence-based strategy, druggable modification, and bispecific inhibitors strategy.

Serum sclerostin and adverse outcomes in elderly patients with stable coronary artery disease undergoing percutaneous coronary intervention

BACKGROUND

Recently, sclerostin, a bone-derived protein, has been shown to play a key role in atherosclerosis progression. However, few studies have investigated the influence of sclerostin on cardiovascular disease prognosis. We investigated the relationship between serum sclerostin levels and adverse outcomes in elderly patients with stable coronary artery disease (SCAD) who were undergoing percutaneous coronary intervention (PCI).

METHODS

We enrolled 310 elderly SCAD patients who underwent PCI in this study and followed them 3 years. According to the median serum sclerostin levels, subjects were stratified into a low sclerostin (low scl) group (n = 144) and a high sclerostin (high scl) group (n = 166). Time-to-event analyses were performed with the Kaplan-Meier method. Associations between sclerostin levels and main adverse cardiovascular and cerebrovascular events (MACCEs) and mortality were evaluated by Cox multivariate regression analysis. The prognostic power of predictive models was verified by the concordance index and receiver operating characteristic curve analysis.

RESULTS

The high scl group had a significantly higher MACCE-free rate and better survival than the low scl group. Serum sclerostin was an independent predictor and could improve the prognostic power for adverse outcomes. In addition, serum sclerostin levels were significantly associated with bone turnover markers, a lower presence of multivessel disease and a lower CCS angina class.

CONCLUSIONS

Serum sclerostin is a prognostic parameter for predicting and intervening in the adverse outcomes of elderly SCAD patients undergoing PCI, which may be explained by its potential role in the bone-vascular axis.

Relationship between sclerostin and coronary tortuosity in postmenopausal females with non-obstructive coronary artery disease

BACKGROUND

Coronary tortuosity (CT) is commonly encountered in postmenopausal females and is usually present without obstructive lesions. Circulating sclerostin levels are elevated in postmenopausal females. In view of sclerostin's vasculoprotective effect, we aimed to find possible association between circulating sclerostin and CT.

METHOD

We prospectively enrolled 273 consecutive postmenopausal females with non-obstructive coronary artery disease diagnosed by coronary angiography. Presence and severity (by tortuosity score) of CT as well as serum sclerostin levels were assessed for each patient.

RESULTS

Patients with CT (128, 47% of study group) were significantly older (P < 0.001), with higher prevalence of hypertension (P = 0.001) and had significantly higher levels of both sclerostin (P < 0.001) and hs-CRP (P = 0.001). Multivariate binary logistic regression revealed that the presence of CT (dependent variable) was associated with high sclerostin level (OR 8.9, 95% CI: 4.9-16.2, P < 0.001). Using ROC curve analysis, Sclerostin at a cut-off value of >650 pg/ml was found to be associated with presence of CT (AUC 0.69, 95% CI: 0.61-0.75, P < 0.001) with sensitivity and specificity of 75% and 72.4%, respectively. Using Pearson's correlation analysis, significant positive correlation between sclerostin and severity of CT was found (r = 0.29, P = 0.001).

CONCLUSION

High circulating sclerostin is associated with the presence and severity of CT in postmenopausal females. This may add to the literature on the incompletely understood pathogenesis of CT.

Evaluating the cardiovascular safety of sclerostin inhibition using evidence from meta-analysis of clinical trials and human genetics

Inhibition of sclerostin is a therapeutic approach to lowering fracture risk in patients with osteoporosis. However, data from phase 3 randomized controlled trials (RCTs) of romosozumab, a first-in-class monoclonal antibody that inhibits sclerostin, suggest an imbalance of serious cardiovascular events, and regulatory agencies have issued marketing authorizations with warnings of cardiovascular disease. Here, we meta-analyze published and unpublished cardiovascular outcome trial data of romosozumab and investigate whether genetic variants that mimic therapeutic inhibition of sclerostin are associated with higher risk of cardiovascular disease. Meta-analysis of up to three RCTs indicated a probable higher risk of cardiovascular events with romosozumab. Scaled to the equivalent dose of romosozumab (210 milligrams per month; 0.09 grams per square centimeter of higher bone mineral density), the SOST genetic variants were associated with lower risk of fracture and osteoporosis (commensurate with the therapeutic effect of romosozumab) and with a higher risk of myocardial infarction and/or coronary revascularization and major adverse cardiovascular events. The same variants were also associated with increased risk of type 2 diabetes mellitus and higher systolic blood pressure and central adiposity. Together, our findings indicate that inhibition of sclerostin may elevate cardiovascular risk, warranting a rigorous evaluation of the cardiovascular safety of romosozumab and other sclerostin inhibitors.

Safety of Romosozumab in Osteoporotic Men and Postmenopausal Women: A Meta-Analysis and Systematic Review

Sclerostin is a protein synthesized mainly by osteocytes whose function is to inhibit bone formation. A recent monoclonal antibody, Romosozumab, is able to block sclerostin. The aim of this meta-analysis is to compare the safety of Romosozumab with placebo and alendronate. Five randomized controlled trials that described the safety of Romosozumab in healthy men and postmenopausal women were analyzed. The measures to be compared were the number of adverse events and the number of serious adverse events. Specific results included injection site reaction, arthralgia, nasopharyngitis, and back pain. A total of 11,741 patients were included in this meta-analysis, in three different groups: Romosozumab, alendronate, and placebo. Significant differences were seen between the groups with regard to injection site reaction: 5.88% in the Romosozumab group versus 3.62% in the placebo group (Mantel-Haenszel [M-H] 1.54, confidence interval [95% CI] 1.22-1.96; p < 0.001) and 2.62% in the alendronate group (M-H 1.8, 95% CI 1.32-2.60; p < 0.001). In addition, patients treated with Romosozumab had significantly fewer total adverse events than the alendronate group (M-H 0.85, 95% CI 0.74-0.98; p < 0.05). In conclusion, Romosozumab may have lower adverse effects compared to alendronate and comparable to a placebo, except injection site reactions. Injection site reactions were more with romosozumab compared to alendronate and compared to the placebo as well. Romosozumab appears to have a similar safety profile to bisphosphonates.

Serum Sclerostin, Body Composition, and Sarcopenia in Hemodialysis Patients with Diabetes

Sclerostin (Scl) is an osteoblast-inhibiting glycoprotein that is secreted mainly by osteocytes and is regulated by hormonal changes and skeletal loading. Decreased physical function and high serum Scl concentrations have been reported in chronic renal failure patients but little is known to date about the differences between diabetic and non-diabetic patients on hemodialysis who are susceptible to both sarcopenia and bone fragility. Objective.To determine the prevalence of sarcopenia and its association with serum Scl concentrations and metabolic parameters in 92 patients on hemodialysis. Anthropometric data and physical performance were evaluated in this study. Blood samples were collected for Scl, glucose, cholesterol, triglycerides, calcium, phosphate, PTH, and 25 OH-vitamin D measurements. Lean mass was evaluated using multifrequency electro-bioimpedance after dialysis session. Results. Mean age was 63.3 ± 13.6 years, 63% of patients were male, and 44.6% had diabetes. Mean body mass index (BMI) was higher in diabetics (26.6 ± 5.2 vs. 24.1 ± 3.7; p=0.01) and there were no differences in gait speed and handgrip strength between diabetic and non-diabetic subjects. A low skeletal muscle mass index (SMI) was identified in 65.2% of the participants, and among them 76.7% were men and 36.7% were diabetics. Mean serum Scl was 86.9 ± 39.0 pmol/L, which was higher in men (94.6 ± 41.7; p=0.017), in those individuals with low SMI (94.9 ± 40.7; p < 0.001), and in diabetics (97.2 ± 46.6; p < 0.003). After multivariate analysis and adjustments for potential confounders, high serum Scl was independently associated with low SMI and with the presence of diabetes. The following variables correlated positively with diabetes: blood pressure; BMI; waist circumference; waist/hip ratio; plasma glucose; serum Scl; and fat mass. Conclusions. We found higher serum Scl concentrations in hemodialysis patients with diabetes and these were inversely related to muscle mass.

Denosumab or romosozumab therapy and risk of cardiovascular events in patients with primary osteoporosis: Systematic review and meta- analysis

BACKGROUND

Osteoporosis and cardiovascular (CV) diseases are closely correlated. RANKL/RANK/OPG pathway and Wnt signalling pathway both implicated in the pathogenesis of osteoporosis and cardiovascular diseases. We aimed to investigate the effect of denosumab or romosozumab therapy on cardiovascular outcomes in patients with primary osteoporosis.

METHODS

PubMed, Cochrane library, and EMBASE databases were systematically searched from the inception dates to June 4, 2019. Randomized clinical trials evaluating the effect of denosumab or romosozumab versus active comparators or placebo for at least 6 months in patients with primary osteoporosis or osteopenia were included. Two investigators independently extracted data for study characteristics, outcomes of interest, and risk of bias in accordance with PRISMA guidelines.

RESULTS

17 relevant studies (denosumab: n=11, 13615 participants; romosozumab: n=6, 12219 participants) were included. No associations between denosumab therapy and risk of a composite cardiovascular outcome (1.06 [95 % CI, 0.88-1.28], p=0.54), three-point major adverse cardiovascular event (3P MACE, 1.01 [95 % CI, 0.83-1.23], p=0.93), and four-point major adverse cardiovascular event (4P MACE, 0.99 [95 % CI, 0.83-1.18], p=0.89) were identified. Romosozumab therapy did not increase the risk of composite cardiovascular outcome (1.26 [95 % CI, 0.95-1.68], p=0.11), and 3P MACE (1.41 [95 % CI, 0.99-2.02], p=0.06), while increased the risk of 4P MACE (1.39 [95 % CI, 1.01-1.90], p=0.04) among elderly men and postmenopausal woman with osteoporosis over a period of 12-36 months. Denosumab or romosozumab did not increase or reduce specific cardiovascular outcomes, including CV death or death, myocardial infarction, stroke, atrial fibrillation, heart failure, aortic and intracranial aneurysm, aortic dissection, aortic valve disease and hypertension (all p＞0.05). Sensitivity analysis conducted by random effects model altered the result of 4P MACE in romosozumab (1.36 [0.99-1.87], p=0.06). No other significant difference was detected in the sensitivity analyses and subgroup analyses.

CONCLUSIONS

Denosumab therapy was not associated with any risk of composite and specific cardiovascular outcomes among patients with primary osteoporosis than active comparators or placebo, while romosozumab therapy might increase the risk of 4P MACE.

Cellular senescence in bone

Cellular senescence refers to a process induced by various types of stress that causes irreversible cell cycle arrest and distinct cellular alterations, including profound changes in gene expression, metabolism, and chromatin organization as well as activation/reinforcement of anti-apoptotic pathways and development of a pro-inflammatory secretome or senescence-associated secretory phenotype (SASP). However, because of challenges and technical limitations in identifying and characterizing senescent cells in living organisms, only recently have some of the diverse in vivo roles of these unique cells been discovered. New findings indicate that senescent cells and their SASP can have acute beneficial functions, such as in tissue regeneration and wound healing. However, in contrast, when senescent cells accumulate in excess chronically at sites of pathology or in old tissues they drive multiple age-associated chronic diseases. Senotherapeutics that selectively eliminate senescent cells ("senolytics") or inhibit their detrimental SASP ("senomorphics") have been developed and tested in aged preclinical models. These studies have established that targeting senescence is a powerful anti-aging strategy to improve "healthspan" - i.e., the healthy period of life free of chronic disease. The roles of senescence in mediating age-related bone loss have been a recent focus of rigorous investigation. Studies in mice and humans demonstrate that with aging, at least a subset of most cell types in the bone microenvironment become senescent and develop a heterogeneous SASP. Furthermore, age-related bone loss can be alleviated in old mice, with apparent advantages over anti-resorptive therapy, by reducing the senescent cell burden genetically or pharmacologically with the first class of senolytics or a senomorphic. Collectively, these findings point to targeting senescence as a transformational strategy to extend healthspan, therefore providing strong rationale for identifying and optimizing senotherapeutics to alleviate multiple chronic diseases of aging, including osteoporosis, and set the stage for translating senotherapeutics to humans, with clinical trials currently ongoing.

Clinical advantages and disadvantages of anabolic bone therapies targeting the WNT pathway

The WNT signalling pathway is a key regulator of bone metabolism, particularly bone formation, which has helped to define the role of osteocytes - the most abundant bone cells - as orchestrators of bone remodelling. Several molecules involved in the control of the WNT signalling pathway have been identified as potential targets for the development of bone-building therapeutics for patients with osteoporosis. Several of these molecules have been investigated in animal models, but only inhibitors of sclerostin (which is produced by osteocytes) have been investigated in phase III clinical studies. Here, we review the rationale for these developments and the specificity and potential off-target actions of WNT-based therapeutics. We also describe the available preclinical and clinical studies and discuss the benefits and risks of using sclerostin inhibitors for the management of patients with osteoporosis.

A review of bone metabolism and developments in medical treatment of the diabetic Charcot foot

Charcot foot is a rare but severe, and possibly limb-threatening, complication to neuropathy and diabetes mellitus. The current treatment consists of long-term off-loading, and has a large negative impact on the patient's life. Much research has gone into understanding the condition and its biochemical mechanisms, however, the underlying pathogenesis of a Charcot foot is not yet fully understood. In the recent decades several key advances in our understanding of the Charcot foot have been made, both in regards to the changes in bone metabolism and structure an acute Charcot foot can cause, and to the molecular pathways involved in this. This review summerizes the available research into the bone metabolism around a Charcot foot, with an emphasis on the biochemical profile. The existing data regarding attempts at medical treatment is also reviewed, including novel trials targetting specific inflammatory pathways upregulated in the acute diabetic Charcot foot.

Circulating levels of sclerostin are associated with cardiovascular mortality

Cardiovascular diseases are a health problem throughout the world, especially in people with diabetes. The identification of cardiovascular disease biomarkers can improve risk stratification. Sclerostin is a modulator of the Wnt/β-catenin signalling pathway in different tissues, and it has recently been linked to vascular biology. The current study aimed to evaluate the relationship between circulating sclerostin levels and cardiovascular and non-cardiovascular mortality in individuals with and without type 2 diabetes. We followed up a cohort of 130 participants (mean age 56.8 years; 48.5% females; 75 with type 2 diabetes; 46 with prevalent cardiovascular disease) in which serum sclerostin levels were measured at the baseline. Time to death (both of cardiovascular and non-cardiovascular causes) was assessed to establish the relationship between sclerostin and mortality. We found that serum sclerostin concentrations were significantly higher in patients with prevalent cardiovascular disease (p<0.001), and independently associated with cardiovascular mortality (p = 0.008), showing sclerostin to be a stronger predictor of mortality than other classical risk factors (area under the curve = 0.849 vs 0.823). The survival analysis showed that an increase of 10 pmol/L in the serum sclerostin level resulted in a 31% increase in cardiovascular mortality. However, no significant association was observed between sclerostin levels and non-cardiovascular mortality (p = 0.346).

From these results, we conclude that high sclerostin levels are related to mortality due to cardiovascular causes. The clinical implication of these findings is based on the possible use of serum sclerostin as a new biomarker of cardiovascular mortality risk in order to establish preventive strategies.

Romosozumab treatment in postmenopausal women with osteoporosis: a meta-analysis of randomized controlled trials

AIM

To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the safety and efficacy of romosozumab in the treatment of postmenopausal osteoporosis.

METHOD

A comprehensive literature review was performed of PubMed, EMBASE, Cochrane Controlled Trials Registry, and Web of Science for RCTs. Outcome measures were changes in lumbar spine, total hip and femoral neck bone mineral density (BMD), incidence of fractures and adverse events. Six trials were finally included.

RESULTS

Romosozumab resulted in a significantly lower risk of new vertebral fracture (relative risk (RR) 0.37, 95% confidence interval (CI) 0.18-0.77, p = 0.005, n = 5371), non-vertebral fracture (RR 0.78, 95% CI 0.66-0.92, p < 0.0001, n = 5635) and hip fracture (RR 0.59, 95% CI 0.44-0.79, p = 0.0004, n = 5635) compared with other therapies. The BMD was significantly increased at the lumbar spine (weighted mean difference (WMD) 13.33, 95% CI 11.41-15.25, p < 0.00001, n = 198), total hip (WMD 5.09, 95% CI 3.81-6.38, p < 0.00001, n = 184) and femoral neck (WMD 4.70, 95% CI 3.50-5.90, p < 0.00001, n = 175) compared with placebo. There was no significant difference in the incidence of adverse events in patients with romosozumab compared to other therapies (RR 1.00, 95% CI 0.98-1.02).

CONCLUSION

In postmenopausal women with osteoporosis who were at high risk for fracture, romosozumab treatment resulted in a significantly lower risk of fracture. Romosozumab 210 mg monthly showed the largest gains in BMD, and was generally well tolerated.

A Wnt-Responsive PDL Population Effectuates Extraction Socket Healing

Stem cells residing in the periodontal ligament (PDL) support the homeostasis of the periodontium, but their in vivo identity, source(s), and function(s) remain poorly understood. Here, using a lineage-tracing mouse strain, we identified a quiescent Wnt-responsive population in the PDL that became activated in response to tooth extraction. The Wnt-responsive population expanded by proliferation, then migrated from the PDL remnants that remained attached to bundle bone, into the socket. Once there, the Wnt-responsive progeny upregulated osteogenic protein expression, differentiated into osteoblasts, and generated the new bone that healed the socket. Using a liposomal WNT3A protein therapeutic, we showed that a single application at the time of extraction was sufficient to accelerate extraction socket healing 2-fold. Collectively, these data identify a new stem cell population in the intact periodontium that is directly responsible for alveolar bone healing after tooth removal.

MANAGEMENT OF ENDOCRINE DISEASE: Novel anabolic treatments for osteoporosis

Skeletal anabolic agents enhance bone formation, which is determined by the number and function of osteoblasts. Signals that influence the differentiation and function of cells of the osteoblast lineage play a role in the mechanism of action of anabolic agents in the skeleton. Wnts induce the differentiation of mesenchymal stem cells toward osteoblasts, and insulin-like growth factor I (IGF-I) enhances the function of mature osteoblasts. The activity of Wnt and IGF-I is controlled by proteins that bind to the growth factor or to its receptors. Sclerostin is a Wnt antagonist that binds to Wnt co-receptors and prevents Wnt signal activation. Teriparatide, a 1-34 amino terminal fragment of parathyroid hormone (PTH), and abaloparatide, a modified 1-34 amino terminal fragment of PTH-related peptide (PTHrp), induce IGF-I, increase bone mineral density (BMD), reduce the incidence of vertebral and non-vertebral fractures and are approved for the treatment of postmenopausal osteoporosis. Romosozumab, a humanized anti-sclerostin antibody, increases bone formation, decreases bone resorption, increases BMD and reduces the incidence of vertebral fractures. An increased incidence of cardiovascular events has been associated with romosozumab, which is yet to be approved for the treatment of osteoporosis. In conclusion, cell and molecular studies have formed the foundation for the development of new anabolic therapies for osteoporosis with proven efficacy on the incidence of new fractures.

Bone diseases: Romosozumab - on track or derailed?

Romosozumab, a recently developed sclerostin inhibitor, stimulates bone formation and inhibits bone resorption, thereby markedly increasing bone mass and reducing fracture risk. But will a red flag regarding possible adverse cardiovascular events derail this promising new drug for osteoporosis?