Denosumab treatment effects on structural damage, bone mineral density, and bone turnover in rheumatoid arthritis: a twelve-month, multicenter, randomized, double-blind, placebo-controlled, phase II clinical trial

Association of denosumab with serum cytokines, chemokines, and bone-related factors in patients with rheumatoid arthritis: A post hoc analysis of a multicentre, open-label, randomised, parallel-group study

OBJECTIVES

To clarify changes in serum cytokines, chemokines, and bone-related factors during denosumab treatment in rheumatoid arthritis (RA) patients.

METHODS

This was a post hoc analysis of a multicentre, open-label, randomised, parallel-group study. Patients were randomly assigned to continue treatment with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) plus receive treatment with denosumab (csDMARDs plus denosumab group) or to continue treatment with csDMARD therapy alone for 12 months. Serum biomarker levels were measured at baseline and at 6 and 12 months.

RESULTS

Baseline and 6-month data from the csDMARDs plus denosumab (n = 22) and csDMARD therapy alone (n = 22) groups were analysed. Statistically significant changes from baseline were seen: Dickkopf-related protein 1 decreased at 6 and 12 months (both groups); osteopontin decreased at 6 months in the csDMARDs plus denosumab group; osteopontin and soluble CD40 ligand increased at 6 and 12 months in the csDMARD therapy alone group; osteocalcin decreased at 6 and 12 months, epidermal growth factor decreased at 12 months, and macrophage-derived chemokine decreased at 6 months in the csDMARDs plus denosumab group; and interferon gamma-induced protein-10 increased at 12 months in the csDMARD therapy alone group.

CONCLUSIONS

Denosumab may inhibit bone destruction by suppressing bone-related factors/chemokines.

The interplay of rheumatoid arthritis and osteoporosis: exploring the pathogenesis and pharmacological approaches

Rheumatoid arthritis (RA) and osteoporosis are two chronic disorders that are often seen together. RA is an autoimmune disorder that causes pain and inflammation in the joints, while osteoporosis is a disorder in which the bones become weak and fragile. Risk factors for bone loss in RA include disease activity, longer disease duration, erosive disease, autoantibody positivity, and joint damage leading to impaired physical activity. Recent research has shown that there is a complex interplay between immune cells, cytokines, and bone remodeling processes in both RA and osteoporosis. The bone remodeling process is regulated by cytokines and immune system signaling pathways, with osteoclasts activated through the RANK/RANKL/OPG pathway and the Wnt/DKK1/sclerostin pathway. Understanding these mechanisms can aid in developing targeted therapies for treatment of osteoporosis in RA patients. Current pharmacological approaches include anti-osteoporotic drugs such as bisphosphonates, denosumab, teriparatide, abaloparatide, raloxifene, and romosozumab. Conventional disease-modifying antirheumatic drugs such as methotrexate and biologicals including TNF inhibitors, IL-6 inhibitors, rituximab, and abatacept lower disease activity in RA and can improve bone metabolism by reducing inflammation but have limited impact on bone mineral density. This review will shed light on the relationship between osteoporosis and rheumatoid arthritis as well as the various factors that influence the onset of osteoporosis in RA patients. We also explore several treatment approaches to effectively managing osteoporosis in RA patients.

New Horizons: Translational Aspects of Osteomorphs

Osteomorphs are a newly described osteoclast lineage cell in mice, which are suggested to play a significant role in the maintenance of bone resorption. Preclinical investigations revealed that osteomorphs are generated through the fission of multinucleated bone-resorbing osteoclasts and can also re-fuse with existing osteoclasts. Modifications to RANKL signaling have been shown to alter cycles of fission and re-fusion of osteomorphs in mice. These novel findings were also shown to contribute to the rebound phenomenon after cessation of anti-RANKL therapy in mice. Moreover, the absence of osteomorph-specific genes in mice exhibits bone structural and quality phenotypes. Given these insights, it could be speculated that osteomorphs play a significant role in bone homeostasis, bone metabolic diseases, and response to therapeutics. In this review, we discuss these potential translational roles for osteomorphs. Importantly, we highlight the need for future preclinical and clinical studies to verify the presence of osteomorphs in humans and explore further the translational implications of this discovery.

Toll-like receptor-2 induced inflammation causes local bone formation and activates canonical Wnt signaling

It is well established that inflammatory processes in the vicinity of bone often induce osteoclast formation and bone resorption. Effects of inflammatory processes on bone formation are less studied. Therefore, we investigated the effect of locally induced inflammation on bone formation. Toll-like receptor (TLR) 2 agonists LPS from Porphyromonas gingivalis and PAM2 were injected once subcutaneously above mouse calvarial bones. After five days, both agonists induced bone formation mainly at endocranial surfaces. The injection resulted in progressively increased calvarial thickness during 21 days. Excessive new bone formation was mainly observed separated from bone resorption cavities. Anti-RANKL did not affect the increase of bone formation. Inflammation caused increased bone formation rate due to increased mineralizing surfaces as assessed by dynamic histomorphometry. In areas close to new bone formation, an abundance of proliferating cells was observed as well as cells robustly stained for Runx2 and alkaline phosphatase. PAM2 increased the mRNA expression of Lrp5, Lrp6 and Wnt7b, and decreased the expression of Sost and Dkk1. In situ hybridization demonstrated decreased Sost mRNA expression in osteocytes present in old bone. An abundance of cells expressed Wnt7b in Runx2-positive osteoblasts and ß-catenin in areas with new bone formation. These data demonstrate that inflammation, not only induces osteoclastogenesis, but also locally activates canonical WNT signaling and stimulates new bone formation independent on bone resorption.

RANKL blockade for erosive hand osteoarthritis: a randomized placebo-controlled phase 2a trial

Erosive hand osteoarthritis (OA) is a prevalent and disabling disease with limited treatment options. Here we present the results of a monocentric, placebo-controlled, double-blind, randomized phase 2a clinical trial with denosumab, a receptor activator of nuclear factor-κB ligand inhibitor, evaluating the effects on structure modification in erosive hand OA. Patients were randomized to 48 weeks treatment with denosumab 60 mg every 3 months (n = 51, 41 females) or placebo (n = 49, 37 females). The primary (radiographic) endpoint was the change in the total Ghent University Scoring System (GUSS) at week 24, where positive changes correspond to remodeling and negative changes to erosive progression. Secondary endpoints were the change in the GUSS at week 48 and the number of new erosive joints at week 48 by the anatomical phase scoring system. Baseline mean GUSS (standard deviation) of target joints was 155.9 (69.3) in the denosumab group and 158.7 (46.8) in the placebo group. The primary endpoint was met with an estimated difference between groups of 8.9 (95% confidence interval (CI) 1.0 to 16.9; P = 0.024) at week 24. This effect was confirmed at week 48 (baseline adjusted GUSS (standard error of the mean) denosumab and placebo were 163.5 (2.9) and 149.2 (3.9), respectively; with an estimated difference between groups of 14.3 (95% CI 4.6 to 24.0; P = 0.003)). At patient level, more new erosive joints were developed in the placebo group compared with denosumab at week 48 (odds ratio 0.24 (95% CI 0.08 to 0.72); P = 0.009). More adverse events occurred in the placebo group (125 events in 44 patients (90%)) compared with the denosumab group (97 events in 41 patients (80%)). These results demonstrate that denosumab has structure modifying effects in erosive hand OA by inducing remodeling and preventing new erosive joints. EU Clinical Trials Register identifier 2015-003223-53 .

Network Pharmacology and Experimental Validation Explore the Pharmacological Mechanisms of Herb Pair for Treating Rheumatoid Arthritis

OBJECTIVE

This study aimed to elucidate the multitarget mechanism of the Mori Ramulus - Taxilli Herba (MT) herb pair in treating rheumatoid arthritis (RA).

METHODS

The targets of the herb pair and RA were predicted from databases and screened through cross-analysis. The core targets were obtained using protein-protein interaction (PPI) network analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed. Finally, animal experiments were conducted to validate the anti-RA effect and mechanism of this herb pair.

RESULTS

This approach successfully identified 9 active compounds of MT that interacted with 6 core targets (AKT1, TNF, IL6, TP53, VEGFA, and IL1β). Pathway and functional enrichment analyses revealed that MT had significant effects on the TNF and IL-17 signaling pathways. The consistency of interactions between active components and targets in these pathways was confirmed through molecular docking. Moreover, the potential therapeutic effect of MT was verified in vivo, demonstrating its ability to effectively relieve inflammation by regulating these targeted genes and pathways.

CONCLUSION

The present work suggests that the therapeutic effect of MT herb pair on RA may be attributed to its ability to regulate the TNF signaling pathway and IL-17 signaling pathway.

Bone Mineral Density is Related to CD4+ T Cell Counts and Muscle Mass is Associated with B Cells in Common Variable Immunodeficiency Patients

BACKGROUND

Common variable immunodeficiency (CVID) is a primary immunodeficiency characterized by chronic/recurrent respiratory infections, bronchiectasis, autoimmunity, inflammatory, gastrointestinal diseases and malignancies associated with a chronic inflammatory state and increased risk of osteoporosis and muscle loss.

AIM

The aim of this study was to evaluate bone mineral density (BMD), body composition and their relationship with lymphocyte subpopulations in CVID patients.

METHODS

Dual-energy X-ray absorptiometry was performed to assess BMD, lean mass, and fat mass in CVID patients. Peripheral blood CD4+, CD8+, and CD19+ cells were measured using flow cytometry.

RESULTS

Thirty-three patients (37.3 ± 10.8 years old) were examined. Although only 11.8% of the individuals were malnourished (BMI <18.5 kg/m2), 27.7% of them had low skeletal muscle mass index (SMI), and 57.6% of them had low BMD. Patients with osteopenia/osteoporosis presented lower weight (p = 0.007), lean mass (p = 0.011), appendicular lean mass (p = 0.011), SMI (p = 0.017), and CD4+ count (p = 0.030). Regression models showed a positive association between CD4+ count and bone/muscle parameters, whereas CD19+ B cell count was only associated with muscle variables. Analysis of ROC curves indicated a cutoff value of CD4+ count (657 cells/mm3; AUC: 0.71, 95% CI 0.52-0.90) which was related to low BMD. Weight (p = 0.004), lean mass (p = 0.027), appendicular lean mass (p = 0.022), SMI (p = 0.029), total bone mineral content (p = 0.005), lumbar (p = 0.005), femoral neck (p = 0.035), and total hip BMD (p<0.001) were found to be lower in patients with CD4+ count below the cutoff.

CONCLUSION

CVID patients presented with low BMD, which was associated with CD4+ count. Moreover, low muscle parameters were correlated with B cell count.

Clinical Impact on Dental Implant Survival in Patients Taking Antiresorptive Medications: A Systematic Review and Meta-Analysis

Dental implants are a predictable option to replace missing teeth. Patients on antiresorptive medications used to treat disorders associated with bone resorption may need dental implants to replace missing teeth. The data on implant failure in patients on antiresorptive medication requiring dental implants, is conflicting and limited. This systematic review aims to investigate if antiresorptive medications have any clinical impact on dental implant survival. Electronic databases were searched until May 2020. The focus question (PICOS): Participants: humans, Interventions: implant placement surgery in patients on antiresorptive medication, Comparisons: patients on antiresorptive medication vs control (patients not on antiresorptive medication), Outcomes: implant survival, and Study design: clinical studies. The protocol of this systematic review was registered in PROSPERO (CRD42020209083). Fourteen nonrandomized studies were selected for data extraction and risk of bias assessment using the ROBINS-1 tool. Only studies with a control were included for the meta-analysis, 8 articles were included in the meta-analysis using implant-level data, and 5 articles were included in the meta-analysis using patient-level data. There was no statistical significance between the 2 groups at the patient level based on 265 patients. However, there was a statistically significant difference at the implant level based on 2697 implants. Therefore, antiresorptive medications, mainly bisphosphonates (BPs), may significantly contribute to implant failure. Antiresorptive medications, especially BPs may reduce implant survival and impair the osseointegration of dental implants. Failed implants in patients on BPs may not lead to osteonecrosis and may be replaced with success.

Denosumab improves bone mineral density and microarchitecture in rheumatoid arthritis: randomized controlled trial by HR-pQCT

INTRODUCTION

This pre-specified exploratory analysis investigated the effect of denosumab on bone mineral density (BMD) and bone microarchitecture in patients with rheumatoid arthritis (RA) treated with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs).

MATERIALS AND METHODS

In this open-label, parallel-group study, patients were randomly assigned (1:1) to continuous treatment with csDMARDs plus denosumab or continuous treatment with csDMARD therapy alone for 12 months. BMD and bone microarchitecture were measured by dual-energy X-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT).

RESULTS

Of 46 patients enrolled in the primary study, 43 were included in the full analysis set. The mean age was 65.3 years, 88.4% were female, and 60.5% had osteoporosis. Areal BMD of the lumbar spine increased from baseline to 6 and 12 months in both groups, but the increase was higher in the csDMARDs plus denosumab group. Areal BMD of the total hip and femoral neck increased from baseline to 6 and 12 months only in the csDMARDs plus denosumab group. Cortical volumetric BMD and cortical thickness of the distal tibia increased in the csDMARDs plus denosumab group at 6 and 12 months but decreased in the csDMARD therapy alone group. Trabecular bone parameters of the distal tibia improved only in the csDMARDs plus denosumab group at 12 months.

CONCLUSION

Denosumab may be recommended for patients with RA treated with csDMARDs to increase BMD and improve bone microarchitecture.

Role of denosumab in bone erosions in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by systemic inflammation and synovitis which evolve into joint destruction and deformity. Bone abnormalities are represented by marginal bone erosions and iuxta-articular and generalized osteoporosis. Overactivation of osteoclasts along with dysregulation of osteoblasts are the key events. Bone resorption is mediated by the receptor activator of nuclear factor (NF)-κB (RANK) ligand (RANK-L), responsible for the differentiation, proliferation, and activation of osteoclasts. RANK-L binds its receptor RANK, localized on the surface of preosteoclasts and mature osteoclasts promoting osteoclastogenesis. High levels of RANK-L were demonstrated in active RA patients. Denosumab, a fully human monoclonal antibody, binds RANK-L and suppresses the RANK-RANK-L signaling pathway leading to the inhibition of osteoclastogenesis. A retrospective analysis of published studies such as clinical trials evidenced the efficacy of denosumab in preventing bone erosion progression in RA patients. Key messages Key questions to answer in future include the following: Could denosumab be associated with other biologic therapies in RA patients? Could denosumab block the progression of bone damage in RA? Could denosumab be used for the prevention of bone erosion in RA?

The comparable efficacy of denosumab on bone mineral density in rheumatoid arthritis patients with postmenopausal osteoporosis: A retrospective case-control study

Little is known about differences in the therapeutic efficacy of denosumab in subjects with and without rheumatoid arthritis (RA). This study compares the changes in bone mineral density (BMD) between RA patients and controls without RA who had been treated with denosumab for 2 years for postmenopausal osteoporosis. A total of 82 RA patients and 64 controls were enrolled, who were refractory to selective estrogen receptor modulators (SERMs) or bisphosphonates and completed the treatment of denosumab 60 mg for 2 years. The efficacy of denosumab in RA patients and controls was assessed using areal BMD (aBMD) and T-score of the lumbar spine, femur neck, and total hip. A general linear model with repeated measures analysis of variance was used to determine differences in aBMD and T-score between 2 study groups. No significant differences in percent changes in aBMD and T-scores by denosumab treatment for 2 years at the lumbar spine, femur neck, and total hip were evident between RA patients and controls (P > .05 of all), except T-score of the total hip (P = .034). Denosumab treatment equally increased aBMD at the lumbar spine and T-scores at the lumbar spine and total hip between RA patients and controls without statistical differences, but RA patients showed less improvement in aBMD at the femur neck (ptime*group = 0.032) and T-scores at the femur neck and total hip than controls (ptime*group = 0.004 of both). Changes in aBMD and T-scores after denosumab treatment in RA patients were not affected by previous use of bisphosphonates or SERMs. Differences of T-score at the femur neck among previous bisphosphonate users and aBMD and T-score at the femur neck and T-scores at the total hip were evident. This study revealed that 2 years of denosumab treatment in female RA patients achieved comparable efficacy on BMD to controls at the lumbar spine, but showed somewhat insufficient improvement at the femur neck and total hip.

Chronic arthritides and bone structure: focus on rheumatoid arthritis-an update

Normal bone remodeling depends of a balance between bone forming cells, osteoblasts and bone resorbing cells, the osteoclasts. In chronic arthritides and some inflammatory and autoimmune diseases such as rheumatoid arthritis, there is a great constellation of cytokines produced by pannus that impair bone formation and stimulate bone resorption by inducing osteoclast differentiation and inhibiting osteoblast maturation. Patients with chronic inflammation have multiple causes that lead to low bone mineral density, osteoporosis and a high risk of fracture including circulating cytokines, impaired mobility, chronic administration of glucocorticoids, low vitamin D levels and post-menopausal status in women, among others. Biologic agents and other therapeutic measures to reach prompt remission might ameliorate these deleterious effects. In many cases, bone acting agents need to be added to conventional treatment to reduce the risk of fractures and to preserve articular integrity and independency for daily living activities. A limited number of studies related to fractures in chronic arthritides were published, and future investigation is needed to determine the risk of fractures and the protective effects of different treatments to reduce this risk.

CXCR3 antagonist NBI-74330 mitigates joint inflammation in Collagen-Induced arthritis model in DBA/1J mice

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by uncontrolled synovial proliferation, pannus formation, cartilage injury, and bone destruction. We used the CXCR3-specific antagonist NBI-74330 to block T-cell-mediated signaling in a DBA/1J mouse model of collagen-induced arthritis (CIA). After CIA induction, DBA/1J mice were treated with NBI-74330 (100 mg/kg) daily from day 21 until day 34 and evaluated for arthritic score and histopathological changes. Furthermore, using flow cytometry, we investigated the effects of NBI-74330 on Th1 (IFN-γ, TNF-α, T-bet, STAT4, Notch-3, and RANKL), Th17 (IL-21, IL-17A, STAT3, and RORγt), and Th22 (IL-22) cells in splenic CD4⁺ and CXCR3⁺T-cells. We also used RT-PCR to assess the effect of mRNA levels of IFN-γ, TNF-α, T-bet, RANKL, IL-17A, RORγt, and IL-22 in knee tissues. The IFN-γ, TNF-α, and IL-17A serum protein levels were measured using ELISA. Compared to vehicle-treated CIA mice, the severity of arthritic scores and histological severity of inflammation decreased significantly in NBI-74330-treated CIA mice. Moreover, compared to vehicle-treated CIA mice, the percentages of CD4⁺IFN-γ⁺, CD4⁺TNF-α⁺, CD4⁺T-bet⁺, CD4⁺STAT4⁺, CD4⁺Notch-3⁺, CXCR3⁺IFN-γ⁺, CXCR3⁺TNF-α⁺, CXCR3⁺T-bet⁺, CXCR3⁺STAT4⁺, CXCR3⁺Notch-3⁺, CD4⁺RANKL⁺, CD4⁺IL-21⁺, CD4⁺IL-17A⁺, CD4⁺STAT3⁺, CD4⁺RORγt⁺, and CD4⁺IL-22⁺ cells decreased in NBI-74330-treated CIA mice. Furthermore, NBI-74330-treatment downregulated IFN-γ, TNF-α, T-bet, RANKL, STAT3, IL-17A, RORγt, and IL-22 mRNA levels. Serum IFN-γ, TNF-α, and IL-17A levels were significantly lower in NBI-74330-treated CIA mice than in vehicle-treated CIA mice. This study demonstrates the antiarthritic effects of NBI-74330 in CIA mice. Therefore, these data suggest that NBI-74330 could be considered a potential RA treatment.

Drug treatment algorithm and recommendations from the 2020 update of the Japan College of Rheumatology clinical practice guidelines for the management of rheumatoid arthritis-secondary publication

OBJECTIVE

The aim of this study was to update the Japan College of Rheumatology (JCR) clinical practice guidelines (CPG) for the management of rheumatoid arthritis (RA; JCR CPG for RA) according to recent changes in the medical environment in Japan. This article is a digest version of the guidance.

METHODS

We used the Grading of Recommendations, Assessment, Development, and Evaluation method to update the 2014 JCR CPG for RA. A consensus was formed by CPG panel members.

RESULTS

We identified 36 important clinical questions regarding drug treatment and developed corresponding recommendations for RA. The recommendations included the following RA medications: non-steroidal anti-inflammatory drugs, corticosteroids, conventional synthetic disease-modifying antirheumatic drugs, biological disease-modifying antirheumatic drugs, anti-receptor activator for nuclear factor-κB ligand antibodies, and Janus kinase inhibitors, as well as the tapering and discontinuation of these medications. Recommendations regarding the efficacy and safety of treatments in the elderly and patients with comorbidities were also developed. Finally, we used these recommendations to create an original algorithm for drug treatment for RA based on the Treat-to-Target approach.

CONCLUSION

The 2020 JCR CPG for RA provides a useful tool for rheumatologists, health care professionals, and patients with RA, enabling shared decision-making in a variety of clinical situations.

How Has Molecular Biology Enhanced Our Undertaking of axSpA and Its Management

PURPOSE

This review aims at investigating pathophysiological mechanisms in spondyloarthritis (SpA). Analysis of genetic factors, immunological pathways, and abnormalities of bone metabolism lay the foundations for a better understanding of development of the axial clinical manifestations in patients, allowing physician to choose the most appropriate therapeutic strategy in a more targeted manner.

RECENT FINDINGS

In addition to the contribution of MHC system, findings emerged about the role of non-HLA genes (as ERAP1 and 2, whose inhibition could represent a new therapeutic approach) and of epigenetic mechanisms that regulate the expression of genes involved in SpA pathogenesis. Increasing evidence of bone metabolism abnormalities secondary to the activation of immunological pathways suggests the development of various bone anomalies that are present in axSpA patients. SpA are a group of inflammatory diseases with a multifactorial origin, whose pathogenesis is linked to the genetic predisposition, the action of environmental risk factors, and the activation of immune response. It is now well known how bone metabolism leads to long-term structural damage via increased bone turnover, bone loss and osteoporosis, osteitis, erosions, osteosclerosis, and osteoproliferation. These effects can exist in the same patient over time or even simultaneously. Evidence suggests a cross relationship among innate immunity, autoimmunity, and bone remodeling in SpA, making treatment approach a challenge for rheumatologists. Specifically, treatment targets are consistently increasing as new drugs are upcoming. Both biological and targeted synthetic drugs are promising in terms of their efficacy and safety profile in patients affected by SpA.

Positive Effects of Biologics on Osteoporosis in Rheumatoid Arthritis

Osteoporosis is a systemic skeletal disorder that causes vulnerability of bones to fracture owing to reduction in bone density and deterioration of the bone tissue microstructure. The prevalence of osteoporosis is higher in patients with autoimmune inflammatory rheumatic diseases, including rheumatoid arthritis (RA), than in those of the general population. In this autoimmune inflammatory rheumatic disease, in addition to known risk factors for osteoporosis, various factors such as chronic inflammation, autoantibodies, metabolic disorders, drugs, and decreased physical activity contribute to additional risk. In RA, disease-related inflammation plays an important role in local or systemic bone loss, and active treatment for inflammation can help prevent osteoporosis. In addition to conventional synthetic disease-modifying anti-rheumatic drugs that have been traditionally used for treatment of RA, biologic DMARDs and targeted synthetic DMARDs have been widely used. These agents can be employed more selectively and precisely based on disease pathogenesis. It has been reported that these drugs can inhibit bone loss by not only reducing inflammation in RA, but also by inhibiting bone resorption and promoting bone formation. In this review, the pathogenesis and research results of the increase in osteoporosis in RA are reviewed, and the effects of biological agents on osteoporosis are discussed.

Regulation of differentiation and generation of osteoclasts in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA), which affects nearly 1% of the world's population, is a debilitating autoimmune disease. Bone erosion caused by periarticular osteopenia and synovial pannus formation is the most destructive pathological changes of RA, also leads to joint deformity and loss of function,and ultimately affects the quality of life of patients. Osteoclasts (OCs) are the only known bone resorption cells and their abnormal differentiation and production play an important role in the occurrence and development of RA bone destruction; this remains the main culprit behind RA.

METHOD

Based on the latest published literature and research progress at home and abroad, this paper reviews the abnormal regulation mechanism of OC generation and differentiation in RA and the possible targeted therapy.

RESULT

OC-mediated bone destruction is achieved through the regulation of a variety of cytokines and cell-to-cell interactions, including gene transcription, epigenetics and environmental factors. At present, most methods for the treatment of RA are based on the regulation of inflammation, the inhibition of bone injury and joint deformities remains unexplored.

DISCUSSION

This article will review the mechanism of abnormal differentiation of OC in RA, and summarise the current treatment oftargeting cytokines in the process of OC generation and differentiation to reduce bone destruction in patients with RA, which isexpected to become a valuable treatment choice to inhibit bone destruction in RA.

Bone resorption during therapy with denosumab in patients with rheumatoid arthritis, positive for the main immunological markers

Objective. Inflammation in rheumatoid arthritis (RA) leads to the development of local and generalized bone loss. Rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibodies (ACCP) are believed to play a negative role in the radiological progression of RA. The use of such antiresorptive therapy as denosumab – monoclonal antibodies to RANKL (receptor activator of nuclear factor kappa-B ligand), reduces the activity of osteoclasts, increases bone mineral density (BMD), and also potentially affects the erosive process at RA. The aim of the study is to evaluate the effect of denosumab therapy on BMD and erosion count in patients with RA and osteoporosis (OP) in consideration of the positivity in the RF and ACCP in serum and the baseline RA activity. Materials and methods. The 12-month prospective study of the efficacy of denosumab therapy (60 mg subcutaneously every 6 months) in patients with RA and OP included 66 postmenopausal women; age – 59.4±7.5 years, duration of RA – 17.8±10.6 years, RF-positive – 47 (72%) patients, ACCP-positive – 48 (74%) patients. At baseline and after 12 months, dual-energy X-ray absorptiometry was performed with an assessment of BMD in the lumbar spine (L1– L4), proximal femur (hip neck and total hip), distal forearm; X-ray of the hands and distal parts of the feet in direct projection, followed by assessment of erosive-destructive changes according to the Sharp/van der Heijde method. Results. A significant increase in BMD was established in all studied sites of the skeleton despite the positivity of the RF and ACCP (for the hip neck p=0.05), while a significant increase in BMD in the RF- and ACCP-negative group was detected only in L1–L4 site. The progression of the increase in erosion count was noted in the RF- and ACCP-positive group while in the RF- and ACCP-negative group this indicator did not change. Regardless of the baseline activity of RA (by DAS28 (Disease Activity Score 28)) the BMD of most parts of the skeleton were stabilized. In patients with moderate RA activity, BMD increased significantly in L1–L4 in both groups: RF- and ACCP-positive and -negative , as well as in the total hip – in RF- and ACCP-positive group. The dynamics of the erosion count in RA patients did not depend on the baseline degree of DAS28 activity, no significant changes were detected in the analyzed groups. Conclusions. RF and ACCP positivity in serum in patients with RA and OP treated with denosumab did not have a negative effect on the dynamics of BMD, while the number of erosions increased. The baseline RA activity level did not affect the dynamics of the erosion count and the dynamics of BMD in most subgroups – BMD levels have been increased or stabilized.

The effect of disease-modifying antirheumatic drugs (DMARDs) on bone homeostasis in rheumatoid arthritis (RA) patients

The autoimmune disease known as rheumatoid arthritis (RA) has been linked to the deterioration of bone. Bone erosion is a hallmark of RA and is linked to the severity of the disease as well as a poor functional result. Erosion of periarticular cortical bone is a common feature seen on plain radiographs of patients with RA. This characteristic feature is the result of excessive bone resorption and inadequate formation of bone. It has been determined that there is a complex interaction between the inflammatory condition seen in RA and bone destruction. Increased knowledge of the pathways and other mechanisms involved in osteoclastogenesis has resulted from advances in both animal and clinical investigations. Also, Biological and targeted medicines have modified RA's bone metabolism. Here, we provide a narrative overview of the literature on the pathomechanisms of bone structure involved in biological and targeted treatments for RA and also, the clinical implications of disease-modifying antirheumatic drugs (DMARDs) are discussed. In light of the fact that these newer treatments present patients with RA with new possibilities for disease improvement and symptom control, it is imperative that additional rigorous evidence be gathered to provide a clinical reference for both patients and their treating physicians.

Porous Silicon-Based Nanomedicine for Simultaneous Management of Joint Inflammation and Bone Erosion in Rheumatoid Arthritis

The lack of drugs that target both disease progression and tissue preservation makes it difficult to effectively manage rheumatoid arthritis (RA). Here, we report a porous silicon-based nanomedicine that efficiently delivers an antirheumatic drug to inflamed synovium while degrading into bone-remodeling products. Methotrexate (MTX) is loaded into the porous silicon nanoparticles using a calcium silicate based condenser chemistry. The calcium silicate-porous silicon nanoparticle constructs (pCaSiNPs) degrade and release the drug preferentially in an inflammatory environment. The biodegradation products of the pCaSiNP drug carrier are orthosilicic acid and calcium ions, which exhibit immunomodulatory and antiresorptive effects. In a mouse model of collagen-induced arthritis, systemically administered MTX-loaded pCaSiNPs accumulate in the inflamed joints and ameliorate the progression of RA at both early and established stages of the disease. The disease state readouts show that the combination is more effective than the monotherapies.

The monocyte-to-osteoclast transition in rheumatoid arthritis: Recent findings

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation leading to joint destruction and deformity. The crucial role of osteoclasts in the bone erosion in RA has been demonstrated. Deregulated osteoclastogenesis which is affected by environmental factors including the inflammatory state, as well as genetic and epigenetic factors, is one of hallmarks of RA pathogenesis. An enhanced-monocyte-to-osteoclast transition plays an important role in osteoclast upregulation in RA because under specific stimuli, circulating monocytes might migrate to a specific location in the bones and fuse with each other to become mature multinucleated osteoclasts. To understand the mechanism of bone damage in RA and to develop novel treatments targeting osteoclast upregulation, it is important to clarify our understanding of the monocyte-to-osteoclast transition in RA. Several potential targets which inhibit both inflammation and osteoclastogenesis, as well as regulators that affect the monocyte-to-osteoclast transition have been revealed by recent studies. Here, we review the factors affecting osteoclastogenesis in RA, summarize the anti-osteoclastogenic effects of current RA treatments, and identify promising therapeutic targets relating to both inflammation and osteoclastogenesis.

Sonic hedgehog promotes synovial inflammation and articular damage through p38 mitogen-activated protein kinase signaling in experimental arthritis

Activated fibroblast-like synoviocytes (FLS) play a pivotal role in synovial inflammation and joint destruction of rheumatoid arthritis (RA). The mechanisms by which sonic hedgehog (SHH) signaling promotes RA FLS-mediated chronic inflammation and tissue damage are not fully understood. The present study aims to determine the role of SHH signaling in the pathogenesis of RA and to explore the potential mechanism(s). We found that the components of SHH signaling were highly expressed in FLS and synovial tissue from patients with RA and in the joint tissue of collagen-induced arthritis (CIA) mice. Overexpression of SHH aggravated the synovial inflammation and joint destruction of CIA and exacerbated cartilage degradation in the cartilage and RA FLS-engrafted severe combined immunodeficiency (SCID) model. Conversely, inhibition of SHH signaling significantly alleviated arthritis severity and reduced cartilage destruction caused by the invasion of RA FLS in vivo. Moreover, we found that p38 mitogen-activated protein kinase (MAPK) cascade was regulated by SHH signaling in RA FLS and the level of phospho-p38 in the joint tissue of CIA was decreased after blockade of SHH signaling. Inhibition of p38 MAPK abolished the effect of SHH overexpression on synovial inflammation and articular destruction of CIA and suppressed the aggressive properties of RA FLS, which were promoted by SHH agonist. In conclusion, our study suggests that SHH signaling aggravates synovial inflammation and joint destruction of experimental arthritis and promotes the abnormal behavior of RA FLS in a p38-dependent manner. SHH-p38 MAPK signaling could be a potential target for the treatment of RA.

Rheumatoid arthritis and osteoimmunology: The adverse impact of a deregulated immune system on bone metabolism

The term osteoimmunology describes an interdisciplinary research field that links the investigation of osteology (bone cells) with immunology. The crosstalk between innate and adaptive immune cells and cells involved in bone remodeling, mainly bone-resorbing osteoclasts and bone-forming osteoblasts, becomes particularly obvious in the inflammatory autoimmune disease rheumatoid arthritis (RA). Besides striking inflammation of the joints, RA causes bone loss, leading to joint damage and disabilities as well as generalized osteoporosis. Mechanistically, RA-associated immune cells (macrophages, T cells, B cells etc.) produce high levels of pro-inflammatory cytokines, receptor activator of nuclear factor κB ligand (RANKL) and autoantibodies that promote bone degradation and at the same time counteract new bone formation. Today, antirheumatic therapy effectively ceases joint inflammation and arrests bone erosion. However, the repair of established bone lesions still presents a challenging task and requires improved treatment options. In this review, we outline the knowledge gained over the past years about the immunopathogenesis of RA and the impact of a dysregulated immune system on bone metabolism.

ETS1 governs pathological tissue-remodeling programs in disease-associated fibroblasts

Fibroblasts, the most abundant structural cells, exert homeostatic functions but also drive disease pathogenesis. Single-cell technologies have illuminated the shared characteristics of pathogenic fibroblasts in multiple diseases including autoimmune arthritis, cancer and inflammatory colitis. However, the molecular mechanisms underlying the disease-associated fibroblast phenotypes remain largely unclear. Here, we identify ETS1 as the key transcription factor governing the pathological tissue-remodeling programs in fibroblasts. In arthritis, ETS1 drives polarization toward tissue-destructive fibroblasts by orchestrating hitherto undescribed regulatory elements of the osteoclast differentiation factor receptor activator of nuclear factor-κB ligand (RANKL) as well as matrix metalloproteinases. Fibroblast-specific ETS1 deletion resulted in ameliorated bone and cartilage damage under arthritic conditions without affecting the inflammation level. Cross-tissue fibroblast single-cell data analyses and genetic loss-of-function experiments lent support to the notion that ETS1 defines the perturbation-specific fibroblasts shared among various disease settings. These findings provide a mechanistic basis for pathogenic fibroblast polarization and have important therapeutic implications.

Mechanisms of joint destruction in rheumatoid arthritis - immune cell-fibroblast-bone interactions

Rheumatoid arthritis (RA) is characterized by inflammation and destruction of bone and cartilage in affected joints. Autoimmune responses lead to increased osteoclastic bone resorption and impaired osteoblastic bone formation, the imbalance of which underlies bone loss in RA, which includes bone erosion, periarticular bone loss and systemic osteoporosis. The crucial role of osteoclasts in bone erosion has been demonstrated in basic studies as well as by the clinical efficacy of antibodies targeting RANKL, an important mediator of osteoclastogenesis. Synovial fibroblasts contribute to joint damage by stimulating both pro-inflammatory and tissue-destructive pathways. New technologies, such as single-cell RNA sequencing, have revealed the heterogeneity of synovial fibroblasts and of immune cells including T cells and macrophages. To understand the mechanisms of bone damage in RA, it is important to clarify how the immune system promotes the tissue-destructive properties of synovial fibroblasts and influences bone cells. The interaction between immune cells and fibroblasts underlies the imbalance between regulatory T cells and T helper 17 cells, which in turn exacerbates not only inflammation but also bone destruction, mainly by promoting RANKL expression on synovial fibroblasts. An improved understanding of the immune mechanisms underlying joint damage and the interplay between the immune system, synovial fibroblasts and bone will contribute to the identification of novel therapeutic targets in RA.

Personalized Therapeutic Strategies in the Management of Osteoporosis in Patients with Autoantibody-Positive Rheumatoid Arthritis

Bone mineral density (BMD) reduction and fragility fractures still represent a major source of morbidity in rheumatoid arthritis (RA) patients, despite adequate control of the disease. An increasing number of clinical and experimental evidence supports the role of autoantibodies, especially anti-citrullinated protein antibodies (ACPAs), in causing localized and generalised bone loss in ways that are both dependent on and independent of inflammation and disease activity. The human receptor activator of nuclear factor kappa B and its ligand—the so-called RANK-RANKL pathway—is known to play a key role in promoting osteoclasts’ activation and bone depletion, and RANKL levels were shown to be higher in ACPA-positive early untreated RA patients. Thus, ACPA-positivity can be considered a specific risk factor for systemic and periarticular bone loss. Through the inhibition of the RANK-RANKL system, denosumab is the only antiresorptive drug currently available that exhibits both a systemic anti-osteoporotic activity and a disease-modifying effect when combined with conventional synthetic or biologic disease-modifying anti-rheumatic drugs (DMARDs). Thus, the combination of DMARD and anti-RANKL therapy could be beneficial in the prevention of fragility fractures and structural damage in the subset of RA patients at risk of radiographic progression, as in the presence of ACPAs.

Differential effects of anti-RANKL monoclonal antibody and zoledronic acid on necrotic bone in a murine model of Staphylococcus aureus-induced osteomyelitis

Osteomyelitis is characterized by progressive inflammatory bone destruction accompanied by severe pain and disability. However, with the exception of antibiotic therapies, there is no established therapy to protect the bone from infectious osteolysis. The anti-receptor activator of nuclear factor-kB ligand (RANKL) monoclonal antibody (anti-RANKL Ab) is a potential drug based on its proven effectiveness in preventing joint bone erosion in rheumatoid arthritis; however, the efficacy and adverse effects of anti-RANKL Ab in osteomyelitis remain to be investigated. In this study, we investigated the effects of anti-mouse RANKL Ab on acute osteomyelitis and compared them with those of zoledronic acid (ZA) using a murine model. Mice were inoculated with bioluminescent Staphylococcus aureus (Xen 29) on their left femur and then treated with ZA, anti-RANKL Ab, or phosphate-buffered saline as control. A 21-day longitudinal observational study using microcomputed tomography showed that both anti-RANKL Ab and ZA had an osteoprotective effect against infectious osteolysis. However, it was also demonstrated through bioluminescence imaging that ZA delayed the spontaneous reduction of bacterial load and through histology that it increased the amount of necrotic bone, while anti-RANKL Ab did not. Findings from histopathological and in vitro studies suggest that an intense inflammatory response around the necrotic bone could induce osteoclasts in a RANKL-independent manner, leading to the removal of necrotic bone, even after administration of the anti-RANKL Ab therapy. Collectively, anti-RANKL Ab may exert an osteoprotective effect without hampering the removal of the necrotic bone, which serves as a nidus for infection in osteomyelitis.

Dendrobine attenuates osteoclast differentiation through modulating ROS/NFATc1/ MMP9 pathway and prevents inflammatory bone destruction

BACKGROUND

Osteolytic diseases share symptoms such as bone loss, fracture and pain, which are caused by over-activated osteoclasts. Targeting osteoclast differentiation has emerged as a therapeutic strategy clinically. Dendrobine is an alkaloid isolated from Chinese herb Dendrobium nobile, with knowing effects of analgesia and anti-inflammation. The roles of dendrobine on osteoclasts and osteolysis remain unclear.

PURPOSE

Herein, the possible roles of dendrobine in osteoclastogenesis, inflammatory osteolysis and the underlying mechanism were explored.

METHODS

Bone marrow-derived macrophages (BMMs) and RAW264.7 cells were employed to evaluate the roles of dendrobine on osteoclastogenesis, bone absorption and the underlying mechanism in vitro. LPS injection was used to cause inflammatory osteolysis in vivo.

RESULTS

Dendrobine repressed osteoclastogenesis, bone resorption induced by receptor activator of nuclear factor kappa B ligand (RANKL) in vitro. Mechanistically, dendrobine inhibited RANKL-upregulated intracellular (ROS), p-p38, c-Fos expression and nuclear factor of activated T cells (NFATc1) nuclear translocation. Osteoclastic genes were reduced, and among them matrix metalloproteinase 9 (MMP9) mRNA was dramatically blocked by dendrobine. Moreover, it substantially suppressed MMP9 protein expression during osteoclastogenesis in vitro. Accordingly, oral 20 mg/kg/day dendrobine was capable of preventing LPS-induced osteolysis with decreased osteoclasts in vivo.

CONCLUSION

Taken together, dendrobine suppresses osteoclastogenesis through restraining ROS, p38-c-Fos and NFATc1-MMP9 in vitro, thus attenuates inflammatory osteolysis in vivo. This finding supports the discover of dendrobine as a novel osteoclast inhibitor for impeding bone erosion in the future.

Therapeutic efficacy of denosumab for rheumatoid arthritis: a systematic review and meta-analysis

OBJECTIVES

Denosumab is used for osteoporosis because it inhibits osteoclast maturation and suppresses bone resorption. Although denosumab is expected to inhibit the bone erosion in RA, its therapeutic efficacy is not well established. The aim of this study was to estimate the effects of denosumab on RA through a meta-analysis.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. PubMed, Web of Science and Scopus were searched for original studies providing information on BMD, joint destruction and disease activity in denosumab-treated RA. A random-effects model was used in the meta-analysis.

RESULTS

Of the 367 studies identified, 18 met the selection criteria. The BMDs of the lumbar spine, total hip and femoral neck at 12 months after denosumab treatment increased by 5.27% (95% CI: 4.37, 6.18), 2.82% (2.46, 3.18) and 3.07% (2.66, 3.48), respectively. In the sensitivity analysis, age and sex tended to influence the effect of denosumab therapy on the rate of variation of BMD, but not glucocorticoid use. The changes in the modified total sharp, erosion and joint space narrowing scores at 12 months after denosumab treatment were significantly smaller with denosumab than with placebo, although the DAS did not change after denosumab treatment.

CONCLUSION

Although denosumab has an inhibitory effect on the bone resorption in RA, its effects might be influenced by the age and sex of RA patients, but not by glucocorticoid use.

The Efficacy of Denosumab in Patients With Rheumatoid Arthritis: A Systematic Review and Pooled Analysis of Randomized or Matched Data

Objective

The purpose of this study was to evaluate the efficacy of denosumab treatment in patients with rheumatoid arthritis (RA).

Methods

The Medline, Embase and Cochrane Library databases were searched for relevant clinical studies. Studies that assessed the efficacy of denosumab in patients with RA were identified. The primary endpoints were the percent changes in bone mineral density (BMD), and the changes in modified total Sharp score (mTSS), modified Sharp erosion score and joint space narrowing (JSN) score. Pooled analyses were calculated using random-effect models.

Results

After searching the literature and performing further detailed assessments, 10 studies with a total of 1758 patients were included in the quantitative analysis. Pooled analyses showed that denosumab treatment significantly increased the percent changes in lumbar spine BMD [mean difference (MD): 5.12, confidence intervals (CI): 4.15 to 6.09], total hip BMD (MD: 2.72, 95% CI: 1.80 to 3.64) and femoral neck BMD (MD: 2.20, 95% CI: 0.94 to 3.46) compared with controls. Moreover, denosumab treatment significantly decreased the changes in mTSS (MD: -0.63, 95% CI: -0.86 to -0.41) and modified Sharp erosion score (MD: -0.62, 95% CI: -0.88 to -0.35). Subgroup analysis indicated that denosumab was superior to bisphosphonates for the improvement of BMD and the mitigation of joint destruction.

Conclusion

Denosumab treatment was associated with increased BMD and alleviated progression of joint destruction in RA patients, even when compared with bisphosphonates.

Inhibition of bone erosion, determined by high-resolution peripheral quantitative computed tomography (HR-pQCT), in rheumatoid arthritis patients receiving a conventional synthetic disease-modifying anti-rheumatic drug (csDMARD) plus denosumab vs csDMARD therapy alone: an open-label, randomized, parallel-group study

BACKGROUND

This exploratory study compared the inhibition of bone erosion progression in rheumatoid arthritis (RA) patients treated with a conventional synthetic disease-modifying anti-rheumatic drug (csDMARD) plus denosumab versus csDMARD therapy alone and investigated the effects of denosumab on bone micro-architecture and other bone-related parameters using high-resolution peripheral quantitative computed tomography (HR-pQCT).

METHODS

In this open-label, randomized, parallel-group study, patients with RA undergoing treatment with a csDMARD were randomly assigned (1:1) to continue csDMARD therapy alone or to continue csDMARDs with denosumab (60-mg subcutaneous injection once every 6 months) for 12 months. The primary endpoint was the change from baseline in the depth of bone erosion, measured by HR-pQCT, in the second and third metacarpal heads at 6 months after starting treatment. Exploratory endpoints were also evaluated, and adverse events (AEs) were monitored for safety.

RESULTS

In total, 46 patients were enrolled, and 43 were included in the full analysis set (csDMARDs plus denosumab, N = 21; csDMARD therapy alone, N = 22). Most patients were female (88.4%), and the mean age was 65.3 years. The adjusted mean (95% confidence interval) change from baseline in the depth of bone erosion, measured by HR-pQCT, in the 2-3 metacarpal heads at 6 months was - 0.57 mm (- 1.52, 0.39 mm) in the csDMARDs plus denosumab group vs - 0.22 mm (- 0.97, 0.53 mm) in the csDMARD therapy alone group (between-group difference: - 0.35 mm [- 1.00, 0.31]; P = 0.2716). Similar results were shown for the adjusted mean between-group difference in the width and volume of bone erosion of the 2-3 metacarpal heads. Significant improvements in bone micro-architecture parameters were shown. The incidence of AEs and serious AEs was similar between the csDMARDs plus denosumab and the csDMARD therapy alone groups (AEs: 52.2% vs 56.5%; serious AEs: 4.3% vs 8.7%).

CONCLUSIONS

Although the addition of denosumab to csDMARDs did not find statistically significant improvements in bone erosion after 6 months of treatment, numerical improvements in these parameters suggest that the addition of denosumab to csDMARDs may be effective in inhibiting the progression of bone erosion and improving bone micro-architecture.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry, UMIN000030575. Japan Registry for Clinical Trials, jRCTs071180018.

Regulation of TNF-Induced Osteoclast Differentiation

Increased osteoclast (OC) differentiation and activity is the critical event that results in bone loss and joint destruction in common pathological bone conditions, such as osteoporosis and rheumatoid arthritis (RA). RANKL and its decoy receptor, osteoprotegerin (OPG), control OC differentiation and activity. However, there is a specific concern of a rebound effect of denosumab discontinuation in treating osteoporosis. TNFα can induce OC differentiation that is independent of the RANKL/RANK system. In this review, we discuss the factors that negatively and positively regulate TNFα induction of OC formation, and the mechanisms involved to inform the design of new anti-resorptive agents for the treatment of bone conditions with enhanced OC formation. Similar to, and being independent of, RANKL, TNFα recruits TNF receptor-associated factors (TRAFs) to sequentially activate transcriptional factors NF-κB p50 and p52, followed by c-Fos, and then NFATc1 to induce OC differentiation. However, induction of OC formation by TNFα alone is very limited, since it also induces many inhibitory proteins, such as TRAF3, p100, IRF8, and RBP-j. TNFα induction of OC differentiation is, however, versatile, and Interleukin-1 or TGFβ1 can enhance TNFα-induced OC formation through a mechanism which is independent of RANKL, TRAF6, and/or NF-κB. However, TNFα polarized macrophages also produce anabolic factors, including insulin such as 6 peptide and Jagged1, to slow down bone loss in the pathological conditions. Thus, the development of novel approaches targeting TNFα signaling should focus on its downstream molecules that do not affect its anabolic effect.

Bioinformatics-Based Research on Key Genes and Pathways of Intervertebral Disc Degeneration

OBJECTIVE

To find out the pathways and key genes and to reveal disc degeneration pathogenesis based on bioinformatic analyses.

DESIGN

The GSE70362 dataset was downloaded from the GEO (Gene Expression Omnibus) database. Differentially expressed genes (DEGs) between the patients having disc degeneration and healthy controls were screened by Limma package in R language. Critical genes were identified by adopting gene ontologies (GOs), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and protein-protein interaction (PPI) networks.

RESULTS

We identified 112 DEGs, including 60 genes which were upregulated and 52 that were downregulated. Analyses, such as GO and KEGG demonstrated that the DEGs got enriched in 4 biological processes and 2 signaling pathways, mainly related to disc degeneration. The PPI network analyses identified 5 key proteins, CCND1 (cyclin D1), GATA3, TNFSF11, LEF1, and DKK1 (Dickkopf related protein 1).

CONCLUSION

In this study, the DEGs and pathways determined promoted us understand the disc degeneration mechanisms. Also, the study may contribute novel biomarkers for the diagnosis and prevention of disc degeneration, and seek new treatment methods to repair and even regenerate degenerative intervertebral disc.

Loss of mutual protection between human osteoclasts and chondrocytes in damaged joints initiates osteoclast-mediated cartilage degradation by MMPs

Osteoclasts are multinucleated, bone-resorbing cells. However, they also digest cartilage during skeletal maintenance, development and in degradative conditions including osteoarthritis, rheumatoid arthritis and primary bone sarcoma. This study explores the mechanisms behind the osteoclast–cartilage interaction. Human osteoclasts differentiated on acellular human cartilage expressed osteoclast marker genes (e.g. CTSK, MMP9) and proteins (TRAP, VNR), visibly damaged the cartilage surface and released glycosaminoglycan in a contact-dependent manner. Direct co-culture with chondrocytes during differentiation increased large osteoclast formation (p < 0.0001) except when co-cultured on dentine, when osteoclast formation was inhibited (p = 0.0002). Osteoclasts cultured on dentine inhibited basal cartilage degradation (p = 0.012). RNA-seq identified MMP8 overexpression in osteoclasts differentiated on cartilage versus dentine (8.89-fold, p = 0.0133), while MMP9 was the most highly expressed MMP. Both MMP8 and MMP9 were produced by osteoclasts in osteosarcoma tissue. This study suggests that bone-resident osteoclasts and chondrocytes exert mutually protective effects on their ‘native’ tissue. However, when osteoclasts contact non-native cartilage they cause degradation via MMPs. Understanding the role of osteoclasts in cartilage maintenance and degradation might identify new therapeutic approaches for pathologies characterized by cartilage degeneration.

Augmenting MNK1/2 activation by c-FMS proteolysis promotes osteoclastogenesis and arthritic bone erosion

Osteoclasts are bone-resorbing cells that play an essential role in homeostatic bone remodeling and pathological bone erosion. Macrophage colony stimulating factor (M-CSF) is abundant in rheumatoid arthritis (RA). However, the role of M-CSF in arthritic bone erosion is not completely understood. Here, we show that M-CSF can promote osteoclastogenesis by triggering the proteolysis of c-FMS, a receptor for M-CSF, leading to the generation of FMS intracellular domain (FICD) fragments. Increased levels of FICD fragments positively regulated osteoclastogenesis but had no effect on inflammatory responses. Moreover, myeloid cell-specific FICD expression in mice resulted in significantly increased osteoclast-mediated bone resorption in an inflammatory arthritis model. The FICD formed a complex with DAP5, and the FICD/DAP5 axis promoted osteoclast differentiation by activating the MNK1/2/EIF4E pathway and enhancing NFATc1 protein expression. Moreover, targeting the MNK1/2 pathway diminished arthritic bone erosion. These results identified a novel role of c-FMS proteolysis in osteoclastogenesis and the pathogenesis of arthritic bone erosion.

Serum RANKL levels in Chinese patients with ankylosing spondylitis: a meta-analysis

Objective

We aimed to determine the association between serum receptor activator of nuclear factor-kappa B ligand (sRANKL) levels and ankylosing spondylitis (AS) in Chinese patients.

Methods

The PubMed, Cochrane Library, Embase, Chinese Biomedical Database, Web of Science, China National Knowledge Infrastructure, VIP, and Wan Fang databases were searched for studies conducted before October 1, 2020, without language restrictions. STATA version 12.0 and Revman version 5.3 were used to analyze the data. The standard mean differences (SMDs) and corresponding 95% confidence intervals (95% CIs) were calculated.

Results

Twelve clinical case–control studies, including 585 patients with AS and 423 healthy controls, were included. The combined SMD for sRANKL suggested that the sRANKL level was significantly higher in Chinese patients with AS than in healthy controls (SMD: 3.27, 95% CI 2.11–4.43, P < 0.00001). Serum RANKL-related factor osteoprotegerin (OPG) levels (SMD: 0.86, 95% CI 0.09–1.64, P < 0.03) were lower in the Chinese patients with AS than in healthy controls, and the RANKL/OPG ratio (SMD = 1.05, 95% CI 0.64–1.46, P < 0.00001) in Chinese patients with AS was approximately the same as that of healthy controls. Subgroup analysis indicated that patients from North and South China had higher sRANKL levels than controls; the sRANKL levels of patients from South China were higher in the subgroup with a Bath Ankylosing Spondylitis Functional Index (BASFI) of > 4 than those of patients in other subgroups. In terms of duration, patients with AS for > 8 years had higher sRANKL levels than health controls. Other subgroup analyses were conducted by region, language, source of control, age, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). In these subgroups, the sRANKL levels were significantly higher in the patients with AS than in healthy controls. The BASFI and BASDAI were sources of heterogeneity.

Conclusions

The sRANKL levels are higher in Chinese patients with AS, especially among those from South China. sRANKL levels may be positively correlated with the pathogenesis of AS among Chinese patients.

Denosumab did not improve computerized tomography erosion scores when added to intensive urate-lowering therapy in gout: Results from a pilot randomized controlled trial

BACKGROUND/PURPOSE

Disordered osteoclast activity has been implicated in the pathogenesis of gouty bone erosion. We sought to determine if the addition of denosumab (a monoclonal antibody targeting the receptor activator of nuclear factor kappa-B ligand - RANKL) to intensive urate-lowering therapy (ULT) improves gouty bone erosion.

METHODS

Open-label, parallel-group pilot randomized controlled trial in which 20 participants with gout with at least one confirmed conventional radiographic foot bone erosion were assigned in a 1:1 allocation to receive denosumab (60 mg subcutaneous every 6 months) added to intensive ULT (serum urate ≤5 mg/dL or 300 µmol/L at the time of randomization and continued for the duration of the study), or intensive ULT alone. The primary outcome was the change in the bilateral foot and ankle computed tomography (CT) bone erosion score from baseline to 12 months, assessed by an experienced musculoskeletal radiologist blinded to study assignment. Secondary outcomes included change in serum C-terminal telopeptide (CTX), and patient reported outcomes of pain and function.

RESULTS

Although serum CTX declined markedly in the denosumab/ULT group compared with the ULT alone group, there was no interval change in CT erosion score in either the denosumab/ULT or ULT alone group after one year of follow-up. Other secondary outcomes did not differ between groups. There were two severe adverse events: One patient developed atrial fibrillation (on denosumab/ULT) and another atrial flutter (on ULT alone).

CONCLUSIONS

In this pilot study, denosumab did not offer additional benefit to intensive urate lowering therapy for gouty bone erosion.

The Effect of Discontinuing Denosumab in Patients With Rheumatoid Arthritis Treated With Glucocorticoids

Objective

To evaluate changes in bone turnover and bone mineral density (BMD) in patients with rheumatoid arthritis (RA) receiving glucocorticoids, after discontinuation of denosumab for 12 months.

Methods

We conducted a randomized, double‐blind, placebo‐controlled, phase II study of RA patients. Patients received placebo, denosumab 60 mg, or denosumab 180 mg every 6 months for 12 months and were followed up for an additional 12 months after discontinuation, during which no bone loss prevention therapy was instituted. Changes from baseline in serum C‐terminal telopeptide of type I collagen (CTX), serum procollagen type I N‐terminal propeptide (PINP), and lumbar spine and total hip BMD were evaluated.

Results

In this post hoc analysis of patients treated with glucocorticoids at study baseline (n = 82), levels of CTX and PINP decreased significantly from baseline in both denosumab groups. Following denosumab discontinuation, CTX returned to baseline and was not significantly different from the placebo group 6 and 12 months after discontinuation. Median percentage changes from baseline PINP in those treated with denosumab 60 mg were −0.16% and 15.3% at 6 and 12 months, respectively, after discontinuation (P = 0.062 and P = 0.017, versus placebo); corresponding changes with denosumab 180 mg were 9.0% and 75.8%, respectively (P = 0.018 and P = 0.002 versus placebo). Compared to placebo, lumbar spine and total hip BMD increased in patients receiving denosumab and returned to baseline 12 months after discontinuation. No osteoporotic fractures were reported during treatment or in the off‐treatment period.

Conclusion

In this analysis of short‐term denosumab use in RA patients receiving glucocorticoids, denosumab discontinuation resulted in a gradual increase in bone turnover, which was associated with a return to baseline lumbar spine and total hip BMD.

Impact of denosumab discontinuation on changes in bone mineral density and bone erosion in rheumatoid arthritis patients

OBJECTIVES

This study investigated changes in bone mineral density (BMD) and erosion after denosumab discontinuation in rheumatoid arthritis (RA) patients without osteoporosis who participated in the DESIRABLE study.

METHODS

This multicentre observational study consisted of a prediscontinuation visit (date of final assessment in DESIRABLE) and a postdiscontinuation visit (2.5 years after the last administered dose of denosumab). Percentage change in lumbar spine (LS) BMD from baseline was assessed as the primary endpoint.

RESULTS

Fifty-nine patients were enrolled. The percentage change in LS BMD decreased to baseline levels at the postdiscontinuation visit. Compared with baseline, C-telopeptide of type I collagen levels increased after denosumab discontinuation but most patients had levels within the reference range. Bone erosion scores were not significantly different between the on-treatment period and after denosumab discontinuation (p = .0666) but there was a numerical increase postdiscontinuation. The progression in bone erosion score was significantly reduced in patients whose disease activity was in remission versus those not in remission (p = .0195).

CONCLUSIONS

In RA patients without osteoporosis, denosumab discontinuation can be explored while considering patient background factors (disease activity and risk of fracture) and accounting for progression of bone erosion and LS BMD decrease after withdrawal.

Identifying the preferable rheumatoid arthritis subgroups for intervention with the anti-RANKL antibody denosumab to reduce progression of joint destruction

OBJECTIVES

To clarify which rheumatoid arthritis (RA) patients benefit most from the anti-receptor activator of nuclear factor-κB ligand antibody denosumab to reduce the progression of joint destruction.

METHODS

We pooled patient data from the 12-month, double-blind, placebo-controlled DRIVE (phase II) and DESIRABLE (phase III) studies. In DRIVE, concomitant treatment was limited to methotrexate, salazosulfapyridine and bucillamine. In DESIRABLE, patients could receive any disease-modifying antirheumatic drug. RA patients were randomised to denosumab 60 mg every 6 months (Q6M), every 3 months (Q3M) or placebo. Efficacy was assessed by van der Heijde-modified total Sharp score (mTSS), bone erosion score (ES) and joint space narrowing score (JSNS). Change in mTSS was assessed in subgroups stratified by risk factors for radiographic damage if the interaction factor was significant.

RESULTS

The pooled analysis included 909 patients. Denosumab reduced worsening of mTSS (mean (SD)) at 12 months in the Q6M (0.88 (3.30), p=0.0024) and Q3M (0.66 (2.16), p=0.0002) groups versus placebo (1.50 (3.73)). This reduction in mTSS progression was due to the change in ES (Q6M, 0.44 (1.89), p=0.0006; Q3M, 0.20 (0.86), p<0.0001) versus placebo (0.98 (2.54)); no effect was observed on JSNS. Anti-cyclic citrullinated peptide (CCP) antibodies, glucocorticoid use and baseline ES showed a significant interaction. Denosumab was particularly effective in patients who were anti-CCP antibody positive (p<0.05). Changes in mTSS versus placebo were observed in all denosumab dose groups, regardless of glucocorticoid use and baseline ES.

CONCLUSIONS

Denosumab broadly reduced the progression of joint destruction in RA patients with risk factors for radiographic damage such as especially anti-CCP antibody positivity.

Sonographic assessment of cartilage damage at metacarpal head in rheumatoid arthritis: qualitative versus quantitative methods

OBJECTIVE

To test the validity of the Outcome Measure in Rheumatology (OMERACT) semiquantitative score by comparing with a quantitative method in the sonographic (US) assessment of hyaline cartilage at the metacarpal head (MH) in patients with rheumatoid arthritis (RA) and healthy subjects (HS).

METHODS

The hyaline cartilage from second to fifth MHs of both hands was scanned. Hyaline cartilage was scored semiquantitatively and quantitatively (by measuring cartilage thickness and comparing with reference values). In RA patients, radiographic joint space narrowing (JSN) was scored on the same joints using the Simple Erosion Narrowing Score (SENS).

RESULTS

Four-hundred and eight MHs in 51 RA patients and 320 MHs in 40 HS were evaluated. The OMERACT semiquantitative score was quicker to perform than the quantitative method (6.0 ± 0.5 vs 8.0 ± 1.5 min, p< 0.01). A significant correlation between the US scores (R = 0.68), and between the US scores and the JSN-SENS (R = 0.61 and R = 0.63, for semiquantitative and quantitative method, respectively) was found. The frequency of cartilage abnormalities was similar between the two US methods in RA patients (58.8% and 51.0% RA patients for semiquantitative and quantitative method, p= 0.46), while the former revealed more abnormalities in HS (27.5% and 7.5% of HS, p= 0.02).

CONCLUSION

The higher feasibility of the OMERACT semiquantitative score suggests its use as first-choice method in the evaluation of cartilage damage. However, despite its limits, the quantitative assessment of HC, providing patient-tailored information due to age- and sex-corrected cut-off values, may represent a valid supplement for optimizing the evaluation of cartilage damage in selected cases.

The Emerging Roles of Endocrine Hormones in Different Arthritic Disorders

The relationship between endocrine hormones and the spectrum of rheumatic conditions has long been discussed in the literature, focusing primarily on sexual hormones, such as estrogens, androgens, prolactin (PRL). Estrogens are indeed involved in the pathogenesis of the main inflammatory arthritis thanks to their effects on the immune system, both stimulatory and inhibitory. The PRL system has been discovered in synovial tissue of rheumatoid arthritis (RA) and psoriatic arthritis (PsA), patients and has been propose as a new potential therapeutic target. Besides sexual hormones, in the last years scientific interest about the crosstalk of immune system with other class of hormones has grown. Hormones acting on the bone tissue (i.e. parathyroid hormone, vitamin D) and modulators of the Wnt pathway (i.e. Dickkopf-1) have been demonstrated to play active role in inflammatory arthritis course, defining a new field of research named osteoimmunology. PTH, which is one of the main determinants of Dkkopf-1, plays a crucial role in bone erosions in RA and a correlation between PTH, Trabecular Bone Score (TBS) and disease activity has been found in ankylosing spondylitis (AS). In PSA is under studying the interaction among IL-17 and bone metabolism. The purpose of this review is to discuss and summarize the recent data about the interaction between endocrine hormone and immune system in the main rheumatic disorders, covering in particular the role of bone-related hormones and cytokines. We will describe this relationship from a biochemical, diagnostic and therapeutic perspective, with a particular focus on RA, PsA and AS.

A double-blind, double-dummy, randomized controlled, multicenter trial of 99Tc-methylene diphosphonate in patients with moderate to severe rheumatoid arthritis

Background:

Clinical observational studies revealed that ⁹⁹Tc-methylene diphosphonate (⁹⁹Tc-MDP) could reduce joint pain and swollenness in rheumatoid arthritis (RA) patients. This multicenter, randomized, double-blind, double-dummy study aimed to evaluate the effects of ⁹⁹Tc-MDP plus methotrexate (MTX) vs. MTX alone or ⁹⁹Tc-MDP alone on disease activity and structural damage in MTX-naïve Chinese patients with moderate to severe RA.

Methods:

Eligible patients with moderate to severely active RA were randomized to receive ⁹⁹Tc-MDP plus MTX (n = 59) vs. MTX (n = 59) alone or ⁹⁹Tc-MDP (n = 59) alone for 48 weeks from six study sites across four provinces in China. The primary outcomes were the American College of Rheumatology 20% improvement (ACR20) response rates at week 24 and changes in modified total Sharp score at week 48.

Results:

At week 24, the proportion of participants achieving ACR20 was significantly higher in the MTX + ⁹⁹Tc-MDP combination group (69.5%) than that in the MTX group (50.8%) or ⁹⁹Tc-MDP group (47.5%) (P = 0.03 for MTX + ⁹⁹Tc-MDP vs. MTX, and MTX + ⁹⁹Tc-MDP vs.⁹⁹Tc-MDP, respectively). The participants in the MTX + ⁹⁹Tc-MDP group and the ⁹⁹Tc-MDP group had significantly less important radiographic progression than the participants in the MTX group over the 48 weeks (MTX + ⁹⁹Tc-MDP vs. MTX: P = 0.03, ⁹⁹Tc-MDP vs. MTX: P = 0.03, respectively). There was no significant difference in terms of adverse events (AEs) among the groups. No serious AEs were observed.

Conclusions:

This study demonstrated that the combination of ⁹⁹Tc-MDP with MTX inhibited structural damage and improved disease activity in RA patients compared with MTX and ⁹⁹Tc-MDP monotherapies, without increasing the rate of AEs. Additional clinical studies of ⁹⁹Tc-MDP therapy in patients with RA are warranted.

Trial Registration:

Chictr.org, ChiCTR-IPR-14005684; http://www.chictr.org.cn/showproj.aspx?proj=10088.

TNFα inhibitors reduce bone loss in rheumatoid arthritis independent of clinical response by reducing osteoclast precursors and IL-20

OBJECTIVES

About half of RA patients treated with TNFα inhibitors either do not respond or lose their initial therapeutic response over time. The clinical response is measured by reduction in DAS28, which primarily reflects inflammation. However, other effects of TNFα inhibitors, such as impact on bone erosion, are not assessed by DAS28. We aimed to examine the effect of TNFα inhibitors on bone density, bone biomarkers and cytokine production in responder and non-responder patients and assessed mechanisms of action.

METHODS

BMD in the lumbar spine and femur neck of 117 RA patients was measured by DEXA scan. Bone turnover biomarkers CTX, osteoprotegerin (OPG), osteocalcin and RANKL were measured by ELISA. Levels of 16 cytokines in plasma and in tissue culture supernatants of ex vivo T cells were measured by multiplex assays and ELISA. The effect of treatment with TNFα inhibitors on blood mononuclear cell (MNC) differentiation to osteoclast precursors (OCP) was measured flow cytometry and microscopy.

RESULTS

TNFα inhibitors improved lumbar spine BMD but had modest effects on blood bone biomarkers, irrespective of patients' clinical response. Blood OCP numbers and the ability of monocytes to differentiate to OCP in vitro declined after treatment. Treatment also reduced RANK expression and IL-20 production. BMD improvement correlated with reduced levels of IL-20 in responder patients.

CONCLUSION

This study reveals that TNFα inhibitors reduce lumbar spine bone loss in RA patients irrespective of changes in DAS28. The reduction in bone loss is associated with reduction in IL-20 levels in responder patients.

Effects of Denosumab in Japanese Patients With Rheumatoid Arthritis Treated With Conventional Antirheumatic Drugs: 36-month Extension of a Phase III Study

OBJECTIVE

To evaluate the safety and efficacy of long-term denosumab 60 mg every 6 months (Q6M) or every 3 months (Q3M) in patients with rheumatoid arthritis (RA).

METHODS

This 12-month, randomized, double-blind, placebo-controlled, multicenter, phase III trial with an open-label extension period from 12 to 36 months (DESIRABLE) enrolled Japanese patients with RA treated with placebo (P) for 12 months followed by either denosumab Q6M (P/Q6M) or denosumab Q3M (P/Q3M) for 24 months; denosumab Q6M for 36 months (Q6M/Q6M); or denosumab Q3M for 36 months (Q3M/Q3M). Efficacy was assessed by van der Heijde modified total Sharp score (mTSS), bone erosion score (BES), and joint space narrowing ( JSN) score.

RESULTS

Long-term treatment better maintained mTSS and BES suppression in the P/Q3M and Q3M/ Q3M vs P/Q6M and Q6M/Q6M groups; changes from baseline in total mTSS (standard error) at 36 months were 2.8 (0.4) and 1.7 (0.3) vs 3.0 (0.4) and 2.4 (0.3), respectively, and corresponding changes in BES were 1.3 (0.2) and 0.4 (0.2) vs 1.4 (0.2) and 1.1 (0.2), respectively. No JSN effect was observed. Bone mineral density consistently increased in all groups after denosumab initiation, regardless of concomitant glucocorticoid administration. Serum C-terminal telopeptide of type I collagen decreased rapidly at 1 month postdenosumab administration (in both the initial 12-month [Q3M and Q6M groups] and long-term treatment [P/Q3M and P/Q6M groups] phases). Adverse event incidence leading to study drug discontinuation was similar across treatment groups.

CONCLUSION

Denosumab treatment maintained inhibition of progression of joint destruction up to 36 months. Based on effects on BES progression, higher dosing frequency at an earlier treatment stage may be needed to optimize treatment. Denosumab was generally well tolerated. (ClinicalTrials.gov: NCT01973569).

Effects of RANKL inhibition on promoting healing of bone erosion in rheumatoid arthritis using HR-pQCT: a 2-year, randomised, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the effects of denosumab on erosion healing at 2-4 metacarpophalangeal (MCP) head as determined by high-resolution peripheral quantitative CT (HR-pQCT) in patients with rheumatoid arthritis (RA) with stable disease.

METHODS

This was a randomised, placebo-controlled, double-blind study. Patients with RA with disease activity score 28 joints (DAS28) ≤5.1 were randomised (1:1) to subcutaneous denosumab 60 mg or placebo once every 6 months for 24 months. The primary outcome was erosion healing at MCP 2-4 on HR-pQCT at 12 months. The effects of denosumab on erosion and joint space parameters on HR-pQCT and radiographs, disease activity and health assessment questionnaire-disability index (HAQ-DI) were also examined.

RESULTS

At 24 months, HR-pQCT images were analysed in 98 patients. One-third of the patients achieved sustained low disease activity throughout the study. At 12 months, changes in erosion parameters on HR-pQCT were similar between the two groups. At 24 months, new erosions (19% vs 9%, p=0.009) and erosion progression (18% vs 8%, p=0.019) were more common in the placebo group than the denosumab group. Erosion healing was seen in a significantly higher proportion of patients in the denosumab group (20% vs 6%, p=0.045) at 24 months. No significant changes in joint space parameters on HR-pQCT, van der Heijde-Sharp erosion score, DAS28 and HAQ-DI were observed in the two groups at 12 and 24 months.

CONCLUSION

Although no differences in erosion parameters were observed at 12 months, denosumab was more efficacious than placebo in erosion repair on HR-pQCT after 24 months.

TRIAL REGISTRATION NUMBER

NCT03239080.

Denosumab is not associated with risk of malignancy: systematic review and meta-analysis of randomized controlled trials

The immunomodulatory effects of denosumab have raised concerns for risk of malignancy. This meta-analysis of 25 randomized controlled trials (21,523 patients) shows similar risk of malignancy between denosumab (60 mg every 6 months, up to 48 months) and any comparator. Post-marketing surveillance may detect rare or late-occurring drug effects. Possible increased risk of malignancy in patients treated with denosumab has been concerned due to inhibition of the immune modulator receptor activator of nuclear factor κ-Β ligand (RANKL). We aimed to assess the risk of malignancy associated with denosumab treatment. PubMed and Cochrane Central Register of Controlled Trials were searched up to May 27, 2019 to include all randomized controlled trials of denosumab (60 mg every 6 months) versus any comparator. Trials using higher drug doses for prevention of skeletal-related events were excluded. Data were independently extracted by two reviewers and analyzed using a fixed-effect model to pool risk ratios (RRs) with 95% confidence intervals (CI). Twenty-five trials (21,523 patients) were included. The risk of malignancy was similar between denosumab and other comparators (absolute risk difference 0%, RR 1.08 [95% CI, 0.93-1.24], I² = 0%). Sensitivity analysis based on adequate allocation concealment showed similar results. The risk of malignancy did not differ between groups in any of the subgroup analyses, including stratification by race, individual comparators, indications for treatment, and longer drug exposure (≥ 24 months, 9 studies). The risk ratio of malignancy-related death was similar between groups. Early concerns about a potential increased risk of malignancy resulting from an immunomodulatory effect of denosumab are not supported by evidence from this meta-analysis of 25 RCTs with drug exposure of up to 48 months. Since RCTs with longer observation for safety outcomes are not expected, post-marketing surveillance will be the main means for detection of rare or late-occurring events.

Effect of denosumab on osteolytic lesion activity after total hip arthroplasty: a single-centre, randomised, double-blind, placebo-controlled, proof of concept trial

BACKGROUND

Osteolysis causes recurrent pain and disability after total hip arthroplasty. We investigated the effect of the human monoclonal antibody denosumab on osteolytic lesion activity in patients undergoing revision total hip arthroplasty surgery to show the biological proof of concept for a non-surgical treatment for the disease.

METHODS

We did a phase 2, randomised, double-blind, placebo-controlled, proof of concept superiority trial at Sheffield Teaching Hospitals, Sheffield, UK. Eligible patients aged 30 years or older and scheduled for revision surgery for symptomatic, radiographically confirmed osteolysis were randomly allocated (1:1) to subcutaneous denosumab (60 mg single-dose) or placebo by an independent pharmacist using a random number table. The primary outcome was the between-group difference in osteoclast number per mm of bone surface of biopsies taken from the osteolytic membrane-bone interface at surgery 8 weeks later, measured by quantitative histomorphometry in all patients who underwent revision surgery. Adverse events were analysed in all randomly assigned participants. This trial is registered with the EU Clinical Trials Register (EudraCT 2011-000541-20).

FINDINGS

Between Dec 12, 2012, and June 24, 2018, 51 patients were assessed for eligibility, of whom 24 were randomly assigned to study treatment. Two patients had their revision surgery cancelled for unrelated reasons, leaving 22 patients (ten in the denosumab group) for analysis of the primary outcome. There were 83% fewer osteoclasts at the osteolysis membrane-bone interface in the denosumab versus the placebo group (median 0·05 per mm [IQR 0·11] vs 0·30 mm [0·40], p=0·011). No deaths or treatment-related serious adverse events occurred. Seven adverse events, including one severe adverse event, occurred in four (36%) of 11 patients in the denosumab group. In the placebo group ten adverse events, including three severe adverse events, occurred in five (38%) of 13 patients.

INTERPRETATION

To our knowledge, this is the first clinical trial of an investigational drug for osteolysis that shows tissue-specific biological efficacy. These results justify the need for future trials that target earlier-stage disease to test for clinical efficacy in reducing the need for revision surgery.

FUNDING

Amgen.