Differing effects of denosumab and alendronate on cortical and trabecular bone

Differential effects of teriparatide, denosumab and zoledronate on hip structural and mechanical parameters in osteoporosis; a real-life study

PURPOSE

The aim of this study was to evaluate changes in hip geometry parameters following treatment with teriparatide (TPD), denosumab (Dmab) and zoledronate (ZOL) in real-life setting.

METHODS

We studied 249 patients with osteoporosis (OP) with mean [SD] age of 71.5 [11.1] years divided into 3 treatment groups; Group A received TPD; n = 55, Group B (Dmab); n = 116 and Group C (ZOL); n = 78 attending a routine metabolic bone clinic. Bone mineral density (BMD) was measured by DXA at the lumbar spine (LS), total hip (TH) and femoral neck (FN) prior to treatment and after 2 years (Group A), after a mean treatment duration of 3.3 [1.3] years (Group B) and after 1, 2 and 3 doses of ZOL (Group C) to assess treatment response. Hip structural analysis (HSA) was carried out retrospectively from DXA-acquired femur images at the narrow neck (NN), the intertrochanter (IT) and femoral shaft (FS).

RESULTS

Changes in parameters of hip geometry and mechanical strength were seen in the following treatment. Percentage change in cross-sectional area (CSA): 3.56[1.6] % p = 0.01 and cross-sectional moment of inertia (CSMI): 4.1[1.8] % p = 0.029 increased at the NN only in Group A. Improvement in HSA parameters at the IT were seen in group B: CSA: 3.3[0.67]% p < 0.001, cortical thickness (Co Th): 2.8[0.78]% p = 0.001, CSMI: 5.9[1.3]% p < 0.001, section modulus (Z):6.2[1.1]% p < 0.001 and buckling ratio (BR): - 3.0[0.86]% p = 0.001 with small changes at the FS: CSA: 1.2[0.4]% p = 0.005, Z:1.6 [0.76]%, p = 0.04. Changes at the IT were also seen in Group C (after 2 doses): CSA: 2.5[0.77]% p = 0.017, Co Th: 2.4[0.84]% p = 0.012, CSMI: 3.9[1.3]% p = 0.017, Z:5.2[1.16]% p < 0.001 and BR: - 3.1[0.88]% p = 0.001 and at the NN (following 3 doses): outer diameter (OD): 4.0[1.4]% p = 0.0005, endocortical diameter(ED): 4.3[1.67% p = 0.009, CSA:5.2[1.8]% p = 0.003, CSMI: 9.3[3.8]% p = 0.019.

CONCLUSIONS

Analysis of the effect of OP therapies on hip geometry is useful in understanding the mechanisms of their anti-fracture effect and may provide additional information on their efficacy.

The Sequential Therapy in Osteoporosis

Background

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

Methods

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

Results and Discussion

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

Conclusions

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

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.

Risk comparison of osteonecrosis of the jaw in osteoporotic patients treated with bisphosphonates vs. denosumab: a multi-institutional retrospective cohort study in Taiwan

In this multi-institutional retrospective cohort study, we compared the long-term risk of osteonecrosis of the jaw following the use of denosumab vs. bisphosphonates in osteoporotic patients. After 2-year use, the likelihood of osteonecrosis of the jaw is lower with denosumab compared to bisphosphonates, and the difference increases with time.

PURPOSE

To compare the long-term risk of osteonecrosis of the jaw (ONJ) between osteoporotic patients treated with bisphosphonates (BPs) and denosumab.

METHODS

This multi-institutional retrospective cohort study included patients aged > 40 years with osteoporosis between January 2010 and December 2018. Patients who met the eligibility criteria were divided into BPs and denosumab groups by propensity score matching (PSM). The risk of ONJ of denosumab vs. BPs was estimated using a Cox proportional hazards model and was described by the cumulative incidence rate using the Kaplan-Meier method.

RESULTS

A total of 84,102 patients with osteoporosis were enrolled, among whom, 8962 were eligible for inclusion based on their first-line drug use (denosumab, n = 3,823; BPs, n = 5,139). Following PCM matching (1:1), the BPs and denosumab groups included 3665 patients each. The incidence density of ONJ in the denosumab and BPs matching groups was 1.47 vs. 2.49 events (per 1000 person-years), respectively. The hazard ratio of ONJ in the denosumab vs. BPs group was estimated as 0.581 (95% confidence interval: 0.33-1.04, p = 0.07). The cumulative incidence rates of ONJ in both groups were similar for the first and second years of drug use (p = 0.062), but significantly different from the third year onwards (p = 0.022). The severity of ONJ was not significantly different between the two groups.

CONCLUSION

In osteoporotic patients, after 2 years of use, the likelihood of ONJ being induced by denosumab is lower than that of BPs, and the difference increases with time.

The additive effect of vitamin K supplementation and bisphosphonate on fracture risk in post-menopausal osteoporosis: a randomised placebo controlled trial

This study assessed whether vitamin K, given with oral bisphosphonate, calcium and/or vitamin D has an additive effect on fracture risk in post-menopausal women with osteoporosis. No difference in bone density or bone turnover was observed although vitamin K1 supplementation led to a modest effect on parameters of hip geometry.

PURPOSE

Some clinical studies have suggested that vitamin K prevents bone loss and may improve fracture risk. The aim was to assess whether vitamin K supplementation has an additive effect on bone mineral density (BMD), hip geometry and bone turnover markers (BTMs) in post-menopausal women with osteoporosis (PMO) and sub-optimum vitamin K status receiving bisphosphonate, calcium and/or vitamin D treatment.

METHODS

We conducted a trial in 105 women aged 68.7[12.3] years with PMO and serum vitamin K1 ≤ 0.4 µg/L. They were randomised to 3 treatment arms; vitamin K1 (1 mg/day) arm, vitamin K2 arm (MK-4; 45 mg/day) or placebo for 18 months. They were on oral bisphosphonate and calcium and/or vitamin D. We measured BMD by DXA, hip geometry parameters using hip structural analysis (HSA) software and BTMs. Vitamin K1 or MK-4 supplementation was each compared to placebo. Intention to treat (ITT) and per protocol (PP) analyses were performed.

RESULTS

Changes in BMD at the total hip, femoral neck and lumbar spine and BTMs; CTX and P1NP did not differ significantly following either K1 or MK-4 supplementation compared to placebo. Following PP analysis and correction for covariates, there were significant differences in some of the HSA parameters at the intertrochanter (IT) and femoral shaft (FS): IT endocortical diameter (ED) (% change placebo:1.5 [4.1], K1 arm: -1.02 [5.07], p = 0.04), FS subperiosteal/outer diameter (OD) (placebo: 1.78 [5.3], K1 arm: 0.46 [2.23] p = 0.04), FS cross sectional area (CSA) (placebo:1.47 [4.09],K1 arm: -1.02[5.07], p = 0.03).

CONCLUSION

The addition of vitamin K1 to oral bisphosphonate with calcium and/or vitamin D treatment in PMO has a modest effect on parameters of hip geometry. Further confirmatory studies are needed.

TRIAL REGISTRATION

The study was registered at Clinicaltrial.gov:NCT01232647.

Automated, calibration-free quantification of cortical bone porosity and geometry in postmenopausal osteoporosis from ultrashort echo time MRI and deep learning

BACKGROUND

Assessment of cortical bone porosity and geometry by imaging in vivo can provide useful information about bone quality that is independent of bone mineral density (BMD). Ultrashort echo time (UTE) MRI techniques of measuring cortical bone porosity and geometry have been extensively validated in preclinical studies and have recently been shown to detect impaired bone quality in vivo in patients with osteoporosis. However, these techniques rely on laborious image segmentation, which is clinically impractical. Additionally, UTE MRI porosity techniques typically require long scan times or external calibration samples and elaborate physics processing, which limit their translatability. To this end, the UTE MRI-derived Suppression Ratio has been proposed as a simple-to-calculate, reference-free biomarker of porosity which can be acquired in clinically feasible acquisition times.

PURPOSE

To explore whether a deep learning method can automate cortical bone segmentation and the corresponding analysis of cortical bone imaging biomarkers, and to investigate the Suppression Ratio as a fast, simple, and reference-free biomarker of cortical bone porosity.

METHODS

In this retrospective study, a deep learning 2D U-Net was trained to segment the tibial cortex from 48 individual image sets comprised of 46 slices each, corresponding to 2208 training slices. Network performance was validated through an external test dataset comprised of 28 scans from 3 groups: (1) 10 healthy, young participants, (2) 9 postmenopausal, non-osteoporotic women, and (3) 9 postmenopausal, osteoporotic women. The accuracy of automated porosity and geometry quantifications were assessed with the coefficient of determination and the intraclass correlation coefficient (ICC). Furthermore, automated MRI biomarkers were compared between groups and to dual energy X-ray absorptiometry (DXA)- and peripheral quantitative CT (pQCT)-derived BMD. Additionally, the Suppression Ratio was compared to UTE porosity techniques based on calibration samples.

RESULTS

The deep learning model provided accurate labeling (Dice score 0.93, intersection-over-union 0.88) and similar results to manual segmentation in quantifying cortical porosity (R2 ≥ 0.97, ICC ≥ 0.98) and geometry (R2 ≥ 0.82, ICC ≥ 0.75) parameters in vivo. Furthermore, the Suppression Ratio was validated compared to established porosity protocols (R2 ≥ 0.78). Automated parameters detected age- and osteoporosis-related impairments in cortical bone porosity (P ≤ .002) and geometry (P values ranging from <0.001 to 0.08). Finally, automated porosity markers showed strong, inverse Pearson's correlations with BMD measured by pQCT (|R| ≥ 0.88) and DXA (|R| ≥ 0.76) in postmenopausal women, confirming that lower mineral density corresponds to greater porosity.

CONCLUSION

This study demonstrated feasibility of a simple, automated, and ionizing-radiation-free protocol for quantifying cortical bone porosity and geometry in vivo from UTE MRI and deep learning.

Computed tomography density changes of bone metastases after concomitant denosumab

OBJECTIVE

To evaluate bone density changes at the level of normal trabecular bone and bone metastases (BMs) after denosumab (DM) treatment in oncologic patients.

MATERIALS AND METHODS

We retrospectively evaluated 31 consecutive adult patients with histologically confirmed solid tumors with at least one newly diagnosed bone metastatic lesion detected at CT. Patients received treatment with DM, 120 mg subcutaneous every 28 days for at least 6 months. Bone density was determined at the level of BMs and at the level of normal trabecular bone of lumbar vertebrae using a region of interest (ROI)-based approach.

RESULTS

A progressive increase in CT bone density was demonstrated at the level of normal trabecular bone at 6 months (18% ± 5%) and 12 months (23% ± 7%) after the treatment begins. BMs showed a significant increase in CT bone density (p < 0.05) as compared to baseline after 6 months (57% ± 15%) and 12 months (1.06 ± 0.25 times higher) after treatment.

CONCLUSION

We have found that long-term treatment with DM increases bone density progressively in oncologic patients. This effect can be observed not only at the level of secondary lesions but also at the level of apparently normal trabecular bone and is more pronounced for osteolytic metastases.

Denosumab versus zoledronic acid in elderly patients after hip fracture

BACKGROUND

Two injectable anti-osteoporosis medications, denosumab and zoledronic acid, have been widely used to treat patients with severe osteoporosis. The purpose of this study was to evaluate the real-world effectiveness and adherence of denosumab compared to zoledronic acid in geriatric patients after a hip fracture.

METHODS

A total of 282 patients treated with osteoporotic hip fracture between March 2014 and Aug 2022 were retrospectively reviewed. The patients were asked to select the anti-osteoporosis medication after surgery. Treatment persistence was monitored by follow-up visit to the outpatient clinic at postoperative 2 years.

RESULTS

Of 282 individuals with baseline data, 162 patients took subcutaneous denosumab and 120 patients took intravenous zoledronic acid. At postoperative 2 years, the change in bone mineral density (BMD) from baseline was greater in the denosumab group compared with the zoledronic acid group (p < 0.001). The rate of persistence to denosumab was significantly higher than that for 12-months zoledronic acid (p = 0.01). Serious adverse events were similar in the two groups.

CONCLUSIONS

Our study revealed the effectiveness and patients' persistence for two commonly used anti-osteoporosis agents after hip fracture. In this frail, elderly population, half-yearly denosumab was superior to yearly zoledronic acid in BMD and demonstrated significant higher persistence rate, indicating a potential therapeutic advantage that warrants further validation.

Meta-analysis of Diabetes Mellitus-Associated Differences in Bone Structure Assessed by High-Resolution Peripheral Quantitative Computed Tomography

PURPOSE OF REVIEW

Diabetes mellitus is defined by elevated blood glucose levels caused by changes in glucose metabolism and, according to its pathogenesis, is classified into type 1 (T1DM) and type 2 (T2DM) diabetes mellitus. Diabetes mellitus is associated with multiple degenerative processes, including structural alterations of the bone and increased fracture risk. High-resolution peripheral computed tomography (HR-pQCT) is a clinically applicable, volumetric imaging technique that unveils bone microarchitecture in vivo. Numerous studies have used HR-pQCT to assess volumetric bone mineral density and microarchitecture in patients with diabetes, including characteristics of trabecular (e.g. number, thickness and separation) and cortical bone (e.g. thickness and porosity). However, study results are heterogeneous given different imaging regions and diverse patient cohorts.

RECENT FINDINGS

This meta-analysis assessed T1DM- and T2DM-associated characteristics of bone microarchitecture measured in human populations in vivo reported in PubMed- and Embase-listed publications from inception (2005) to November 2021. The final dataset contained twelve studies with 516 participants with T2DM and 3067 controls and four studies with 227 participants with T1DM and 405 controls. While T1DM was associated with adverse trabecular characteristics, T2DM was primarily associated with adverse cortical characteristics. These adverse effects were more severe at the radius than the load-bearing tibia, indicating increased mechanical loading may compensate for deleterious bone microarchitecture changes and supporting mechanoregulation of bone fragility in diabetes mellitus. Our meta-analysis revealed distinct predilection sites of bone structure aberrations in T1DM and T2DM, which provide a foundation for the development of animal models of skeletal fragility in diabetes and may explain the uncertainty of predicting bone fragility in diabetic patients using current clinical algorithms.

The why and how of sequential and combination therapy in osteoporosis. A review of the current evidence

It is now well recognized that over the lifetime of a patient with osteoporosis, more than one medication will be needed to treat the disease and to decrease fracture risk. Though current gaps in osteoporosis therapy can be potentially mitigated with sequential and combination regimens, how to move seamlessly amongst the multiple treatments currently available for osteoporosis for sustained efficacy is still unclear. Data from recent studies show that an anabolic agent such as teriparatide or romosozumab followed by an antiresorptive affords maximal gain in BMD and possibly better and earlier fracture risk reduction compared to a regimen which follows the opposite sequence. Sequentially moving to a bisphosphonate such as alendronate from an anabolic agent such as abaloparatide has also been shown to preserve the fracture reduction benefits seen with the latter. This sequence of an anabolic agent followed by an antiresorptive should especially be considered in the high-risk patient with imminent fracture risk to rapidly reduce the risk of subsequent fractures. The data surrounding optimum timing of initiation of bisphosphonate therapy following denosumab discontinuation is still unclear. Though data suggests that combining a bisphosphonate with teriparatide does not provide substantial BMD gains compared to monotherapy, the concomitant administration of denosumab with teriparatide has been shown to significantly increase areal BMD as well as to increase volumetric BMD and estimated bone strength. This narrative review explores the available evidence regarding the various sequential and combination therapy approaches and the potential role they could play in better managing osteoporosis.

Current and future targeted alpha particle therapies for osteosarcoma: Radium-223, actinium-225, and thorium-227

Osteosarcoma is a high-grade sarcoma characterized by osteoid formation, nearly universal expression of IGF1R and with a subset expressing HER-2. These qualities provide opportunities for the use of the alpha particle-emitting isotopes to provide targeted radiation therapy via alpha particles precisely to bone-forming tumors in addition to IFG1R or Her-2 expressing metastases. This review will detail experience using the alpha emitter radium-223 (²²³Ra, tradename Xofigo), that targets bone formation, in osteosarcoma, specifically related to patient selection, use of gemcitabine for radio-sensitization, and using denosumab to increasing the osteoblastic phenotype of these cancers. A case of an inoperable left upper lobe vertebral-paraspinal-mediastinal osteoblastic lesion treated successfully with ²²³Ra combined with gemcitabine is described. Because not all areas of osteosarcoma lesions are osteoblastic, but nearly all osteosarcoma cells overexpress IGF1R, and some subsets expressing Her-2, the anti-IGF1R antibody FPI-1434 linked to actinium-225 (²²⁵Ac) or the Her-2 antibody linked to thorium-227 (²²⁷Th) may become other means to provide targeted alpha particle therapy against osteosarcoma (NCT03746431 and NCT04147819).

Denosumab treatment is associated with decreased cortical porosity and increased bone density and strength at the proximal humerus of ovariectomized cynomolgus monkeys

Upper extremity fractures, including those at the humerus, are common among women with postmenopausal osteoporosis. Denosumab was shown to reduce humeral fractures in this population; however, no clinical or preclinical studies have quantified the effects of denosumab on humerus bone mineral density or bone microarchitecture changes. This study used micro-computed tomography (μCT) and computed tomography (CT), alongside image-based finite element (FE) models derived from both modalities, to quantify the effects of denosomab (DMAb) and alendronate (ALN) on humeral bone from acutely ovariectomized (OVX) cynomolgus monkeys. Animals were treated with 12 monthly injections of s.c. vehicle (VEH; n = 10), s.c. denosumab (DMAb; 25 mg/kg, n = 9), or i.v. alendronate (ALN; 50 μg/kg, n = 10). Two more groups received 6 months of VEH followed by 6 months of DMAb (VEH-DMAb; n = 7) or 6 months of ALN followed by 6 months of DMAb (ALN-DMAb; n = 9). After treatment, humeri were harvested and μCT was used to quantify tissue mineral density, trabecular morphology, and cortical porosity at the humeral head. Clinical CT imaging was also used to quantify trabecular and cortical bone mineral density (BMD) at the ultra-proximal, proximal, 1/5 proximal and midshaft of the bone. Finally, μCT-based FE models in compression, and CT-based FE models in compression, torsion, and bending, were developed to estimate differences in strength. Compared to VEH, groups that received DMAb at any time demonstrated lower cortical porosity and/or higher tissue mineral density via μCT; no effects on trabecular morphology were observed. FE estimated strength based on μCT was higher after 12-months DMAb (p = 0.020) and ALN-DMAb (p = 0.024) vs. VEH; respectively, FE predicted mean (SD) strength was 4649.88 (710.58) N, and 4621.10 (1050.16) N vs. 3309.4 (876.09) N. All antiresorptive treatments were associated with higher cortical BMD via CT at the 1/5 proximal and midshaft of the humerus; however, no differences in CT-based FE predicted strength were observed. Overall, these results help to explain the observed reductions in humeral fracture rate following DMAb treatment in women with postmenopausal osteoporosis.

A bibliometric research based on hotspots and frontier trends of denosumab

Denosumab is a monoclonal antibody that targets and inhibits the osteoclast activating factor receptor activator for nuclear factor-κB ligand (RANKL). It has been widely used in the treatment of osteoporosis, giant cell tumors of bone, and in the prevention of malignant skeletal-related events (SREs). We collected the research results and related MeSH terms of denosumab from 2011 to 2021 through the Web of Science and PubMed, respectively. The literature was visualized and analyzed by CiteSpace and bibliometric online analysis platforms. The MeSH terms were biclustered using the Bibliographic Co-Occurrence Analysis System (BICOMB) and graph clustering toolkit (gCLUTO). The results show that the number of denosumab-related annual publications had increased from 51 to 215, with the United States leading and Amgen Inc. being the most influential in the past 10 years. Articles published in the Journal of Bone and Mineral Research had the highest total citations. Three scholars from Shinshu University in Matsumoto, Yukio Nakamura, Takako Suzuki, and Hiroyuki Kato, joined the field relatively late but produced the most. The clinical comparison and combination of denosumab with other drugs in the treatment of osteoporosis was the most significant focus of research. Drug withdrawal rebound and management strategies have gained more attention and controversy recently. MeSH analysis revealed eight major categories of research hotspots. Among them, exploring the multiple roles of the RANK-RANKL-OPG system in tumor progression, metastasis, and other diseases is the potential direction of future mechanism research. It is a valuable surgical topic to optimize the perioperative drug administration strategy for internal spinal fixation and orthopedic prosthesis implantation. Taken together, the advantages of denosumab were broad and cost-effective. However, there were still problems such as osteonecrosis of the jaw, severe hypocalcemia, a high recurrence rate of giant cells in the treatment of bone and individual sarcoidosis, and atypical femoral fractures, which need to be adequately solved.

Alendronate prolongs the reversal-resorption phase in human cortical bone remodeling

Despite their ability to reduce fracture-risk and increase Bone Mineral Density (BMD) in osteoporotic women, bisphosphonates are reported to reduce formation of new bone. Reduced bone formation has been suggested to lead to accumulation of microfractures and contribute to rare side effects in cortical bone such as atypical femur fractures. However, most studies are limited to trabecular bone. In this study, the cortical bone remodeling in human iliac bone specimens of 65 non-treated and 24 alendronate-treated osteoporotic women was investigated using a new histomorphometric classification of intracortical pores. The study showed that only 12.4 ± 11% of the cortical pore area reflected quiescent pores/osteons in alendronate-treated patients versus 8.5 ± 5% in placebo, highlighting that new cortical remodeling events remain to be activated. The percent and size of eroded pores (events in resorption-reversal phase) remained unchanged, but their contribution to total pore area was 1.4-fold higher in alendronate versus placebo treated patients (66 ± 22% vs 48 ± 22%, p < 0.001). On the other hand, the mixed eroded-formative pores (events with mixed resorption-reversal-formation phases) was 2-fold lower in alendronate versus placebo treated patients (19 ± 14% vs 39 ± 23% of total pore area, p < 0.001), and formative pores (event in formation phase) was 2.2-fold lower in alendronate versus placebo treated patients (2.1 ± 2.4% vs 4.6 ± 3.6%, p < 0.01), and their contribution to total pore area was 2.4-fold lower (1.3 ± 2.1% vs 3.1 ± 4.4%, p < 0.05). Importantly, these differences between alendronate and placebo treated patients were significant in patients after 3 years of treatment, not after 2 years of treatment. Collectively, the results support that cortical remodeling events activated during alendronate treatment has a prolonged reversal-resorption phase with a delayed transition to formation, becoming increasingly evident after 3-years of treatment. A potential contributor to atypical femur fractures associated with long-term bisphosphonate treatment.

Temporal changes in cortical microporosity during estrogen deficiency associated with perilacunar resorption and osteocyte apoptosis: A pilot study

Osteocytes can actively regulate bone microporosity, through either perilacunar resorption or micropetrosis following apoptosis. Osteocyte apoptosis is more prevalent in estrogen deficiency and changes in the lacunar-canalicular network of osteocytes have been reported. Temporal changes in bone mineralisation and osteocytes cellular strains occur, which might be associated with osteocyte-driven microporosity changes, although time dependant changes in bone microporosity are not yet fully understood. In this pilot study we conducted micro-CT analysis, backscatter electron imaging and histological analysis of femoral cortical bone form an ovariectomized rat model of osteoporosis to investigate whether estrogen deficiency causes temporal changes in lacunar and vascular porosity. We also assessed MMP14 expression, lacunar occupancy and mineral infilling, as indicators of perilacunar resorption and micropetrosis. We report temporal changes in cortical microporosity in estrogen deficiency. Specifically, canalicular and vascular porosity initially increased (4 weeks post-OVX), coinciding with the period of rapid bone loss, whereas in the longer term (14 weeks post-OVX) lacunar and canalicular diameter decreased. Interestingly, these changes coincided with an increased prevalence of empty lacunae and osteocyte lacunae were observed to be more circular with a mineralised border around the lacunar space. In addition we report an increase in MMP14+ osteocytes, which also suggests active matrix degradation by these cells. Together these results provide an insight into the temporal changes in cortical microporosity during estrogen deficiency and suggest the likelihood of occurrence of both perilacunar resorption and osteocyte apoptosis leading to micropetrosis. We propose that microporosity changes arise due to processes driven by distinct populations of osteocytes, which are either actively resorbing their matrix or have undergone apoptosis and are infilling lacunae by micropetrosis.

Applications of Calcium-Based Nanomaterials in Osteoporosis Treatment

With rapidly aging populations worldwide, osteoporosis has become a serious global public health problem. Caused by disordered systemic bone remodeling, osteoporosis manifests as progressive loss of bone mass and microarchitectural deterioration of bone tissue, increasing the risk of fractures and eventually leading to osteoporotic fragility fractures. As fracture risk increases, antiosteoporosis treatments transition from nonpharmacological management to pharmacological intervention, and finally to the treatment of fragility fractures. Calcium-based nanomaterials (CBNMs) have unique advantages in osteoporosis treatment because of several characteristics including similarity to natural bone, excellent biocompatibility, easy preparation and functionalization, low pH-responsive disaggregation, and inherent pro-osteogenic properties. By combining additional ingredients, CBNMs can play multiple roles to construct antiosteoporotic biomaterials with different forms. This review covers recent advances in CBNMs for osteoporosis treatment. For ease of understanding, CBNMs for antiosteoporosis treatment can be classified as locally applied CBNMs, such as implant coatings and filling materials for osteoporotic bone regeneration, and systemically administered CBNMs for antiosteoporosis treatment. Locally applied CBNMs for osteoporotic bone regeneration develop faster than the systemically administered CBNMs, an important consideration given the serious outcomes of fragility fractures. Nevertheless, many innovations in construction strategies and preparation methods have been applied to build systemically administered CBNMs. Furthermore, with increasing interest in delaying osteoporosis progression and avoiding fragility fracture occurrence, research into systemic administration of CBNMs for antiosteoporosis treatment will have more development prospects. Deep understanding of the CBNM preparation process and optimizing CBNM properties will allow for increased application of CBNMs in osteoporosis treatments in the future.

The effect of denosumab and alendronate on trabecular plate and rod microstructure at the distal tibia and radius: A post-hoc HR-pQCT study

BACKGROUND

Age-related trabecular microstructural deterioration and conversion from plate-like trabeculae to rod-like trabeculae occur because of unbalanced rapid remodeling. As denosumab achieves greater remodeling suppression and lower cortical porosity than alendronate, we hypothesized that denosumab might also preserve trabecular plate microstructure, bone stiffness and strength more effectively than alendronate.

METHODS

In this post hoc analysis of a phase 2 study, postmenopausal women randomized to placebo (P, n = 74), denosumab (D, n = 72), or alendronate (A, n = 68). HR-pQCT scans of the distal radius and tibia were performed at baseline and Month-12 (M12). Trabecular compartment was subjected to Individual Trabecula Segmentation while finite element analysis was performed to estimate stiffness and strength. Percent change from baseline at M12 of each parameter was compared between patient groups.

RESULTS

At the distal tibia, in the placebo group, plate surface area (pTb.S, -1.3%) decreased while rod bone volume fraction (rBV/TV, +4.5%) and number (rTb.N, +2.1%) increased. These changes were prevented by denosumab but persisted despite alendronate therapy (pTb.S: -1.7%; rBV/TV: +6.9%; rTb.N: +3.0%). Both treatments improved whole bone stiffness (D: +3.1%; A: +1.8%) and failure load (D: +3.0%; A: +2.2%); improvements using denosumab was significant compared to placebo (stiffness: p = 0.004; failure load: p = 0.003). At the distal radius, denosumab increased total trabecular bone volume fraction (BV/TV, +3.4%) and whole bone failure load (+4.0%), significantly different from placebo (BV/TV: p = 0.044; failure load: p = 0.046). Significantly different effects of either drug on plate and rod microstructure were not detected.

CONCLUSIONS

Denosumab preserved trabecular plate microstructure. Alendronate did not. However, estimated strength did not differ between denosumab and alendronate treated groups.

Effect of drugs on bone mineral density in postmenopausal osteoporosis: a Bayesian network meta-analysis

Background

Osteoporosis affects mostly postmenopausal women, leading to deterioration of the microarchitectural bone structure and low bone mass, with an increased fracture risk with associated disability, morbidity and mortality. This Bayesian network meta-analysis compared the effects of current anti-osteoporosis drugs on bone mineral density.

Methods

The present systematic review and network meta-analysis follows the PRISMA extension statement to report systematic reviews incorporating network meta-analyses of health care interventions. The literature search was performed in June 2021. All randomised clinical trials that have investigated the effects of two or more drug treatments on BMD for postmenopausal osteoporosis were accessed. The network comparisons were performed through the STATA Software/MP routine for Bayesian hierarchical random-effects model analysis. The inverse variance method with standardised mean difference (SMD) was used for analysis.

Results

Data from 64 RCTs involving 82,732 patients were retrieved. The mean follow-up was 29.7 ± 19.6 months. Denosumab resulted in a higher spine BMD (SMD −0.220; SE 3.379), followed by pamidronate (SMD −5.662; SE 2.635) and zoledronate (SMD −10.701; SE 2.871). Denosumab resulted in a higher hip BMD (SMD −0.256; SE 3.184), followed by alendronate (SMD −17.032; SE 3.191) and ibandronate (SMD −17.250; SE 2.264). Denosumab resulted in a higher femur BMD (SMD 0.097; SE 2.091), followed by alendronate (SMD −16.030; SE 1.702) and ibandronate (SMD −17.000; SE 1.679).

Conclusion

Denosumab results in higher spine BMD in selected women with postmenopausal osteoporosis. Denosumab had the highest influence on hip and femur BMD.

Level of evidence

Level I, Bayesian network meta-analysis of RCTs

Bone-modifying agents for bone loss in patients with prostate cancer receiving androgen deprivation therapy; insights from a network meta-analysis

BACKGROUND

The data of head-to-head comparisons of the effect of bone-modifying agents (BMAs) in patients with androgen deprivation therapy (ADT) for prostate cancer without skeletal metastasis is limited. Thus, we conducted a network meta-analysis to compare each BMA for the efficacy of bone mineral densities (BMDs) and the risk of fracture.

METHODS

We performed a network meta-analysis to compare the change of BMDs and the risk of vertebral fracture in the studies included using a random-effect model. The primary outcomes are the change of BMD of the lumbar spine (LS) and the total hip (TH) from the baseline at 1 year from the initiation of the BMA and the risk of vertebral fracture.

RESULTS

We identified and included 15 studies in this analysis. All BMAs except risedronate showed a significant increase of BMD of the LS compared with groups without BMA, among which zoledronate showed the most BMD gain. At TH, bisphosphonates (alendronate, pamidronate, and zoledronate) and denosumab showed significant elevation compared with the no-BMA group. Denosumab was associated with the most BMD gain at the TH. Only denosumab reduced the risk of vertebral fracture (relative risk [95% confidence interval]: 0.40 [0.20-0.81]). Although zoledronate showed the highest BMD gain at the LS, it did not reduce the risk of vertebral fracture in this analysis.

CONCLUSION

Most bisphosphonates and denosumab significantly increased BMD at the LS and the TH in patients receiving ADT for prostate cancer without skeletal metastasis. In particular, zoledronate and denosumab were the most potent BMAs in terms of BMD increment at the LS and the TH, respectively. However, denosumab, not zoledronate, was the only BMA that showed a significant risk reduction of vertebral fracture. We need further studies to examine the change of bone quality and the effect on the risk of non-vertebral and hip fractures.

A Novel HR-pQCT Image Registration Approach Reveals Sex-Specific Changes in Cortical Bone Retraction With Aging

During aging, changes in endosteal and periosteal boundaries of cortical bone occur that differ between men and women. We here develop a new procedure that uses high-resolution peripheral quantitative CT (HR-pQCT) imaging and 3D registration to identify such changes within the timescale of longitudinal studies. A first goal was to test the sensitivity of the approach. A second goal was to assess differences in periosteal/endosteal expansion over time between men and women. Rigid 3D registration was used to transform baseline and all follow-up (FU) images to a common reference configuration for which the region consisting of complete slices (largest common height) was determined. Periosteal and endosteal contours were transformed to the reference position to determine the net periosteal and endosteal expansion distances. To test the sensitivity, images from a short-term reproducibility study were used (15 female, aged 21 to 47 years, scanned three times). To test differences between men and women, images from a subset of the Geneva Retirees Cohort were used (248 female, 61 male, average age 65 years, 3.5 and 7 years FU). The sensitivity study indicated a least significant change for detecting periosteal/endosteal expansion of 41/31 microns for the radius and 17/26 microns for the tibia. Results of the cohort study showed significant net endosteal retraction only in females at the radius and tibia after 3.5 years (38.0 and 38.4 microns, respectively) that further increased at 7 years FU (70.4 and 70.8 microns, respectively). No significant net periosteal changes were found for males or females at 7 years. The results demonstrate that it is possible to measure changes in endosteal contours in longitudinal studies within several years. For the investigated cohort, significant endosteal retraction was found in females but not in males. Whether these changes in cortical geometry are related to fracture risk remains to be investigated in larger cohorts © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Analysis of the subsequent treatment of osteoporosis by transitioning from bisphosphonates to denosumab, using quantitative computed tomography: A prospective cohort study

Purpose

Denosumab reduces bone resorption and improves bone mineral density (BMD). Studies have analyzed subsequent treatment transitioning from bisphosphonates to denosumab based on dual-energy X-ray absorptiometry scanning (DXA). Quantitative computed tomography (QCT) can help assess cortical and trabecular bones separately in three dimensions without the interference of the surrounding osteophytes. In the present study, we analyzed the subsequent treatment transition from bisphosphonates to denosumab using QCT.

Methods

Thirty-two patients with postmenopausal osteoporosis to be treated with denosumab were recruited. The patients were divided into two groups (15 prior bisphosphonate and 17 naïve) based on their previous treatment. BMD of the lumbar spine and hip were evaluated by DXA and QCT at baseline and 12 months following denosumab treatment.

Results

The percentage change in volumetric BMD assessed by QCT at 12 months significantly improved in the naïve group compared with that in the prior bisphosphonate group. The region-specific assessment of femur at 12 months revealed that denosumab treatment was effective in both cortical and trabecular bones except the trabecular region of the prior bisphosphonate group.

Conclusion

Our study suggests that although denosumab treatment was useful in both treatment groups, BMD increase was significantly higher in the naïve group than in the prior-bisphosphonate group. Interestingly, in the prior-bisphosphonate group, denosumab treatment was more effective in the cortical region than the trabecular region. Our study offers insights into the subsequent treatment and permits greater confidence when switching to denosumab from bisphosphonates.

•

We analyzed the treatment transition from bisphosphonates to denosumab using QCT.

•

Percentage change in volumetric BMD at 12 months significantly improved in the naïve group.

•

Denosumab treatment was more effective on the cortical region than the trabecular region.

•

Our study offers insights into the subsequent treatment when switching to denosumab.

Bone Effect and Safety of One-Year Denosumab Therapy in a Cohort of Renal Transplanted Patients: An Observational Monocentric Study

In 32-kidney transplanted patients (KTxps), the safety and the effects on BMD and mineral metabolism (MM) of one-year treatment with denosumab (DB) were studied. Femoral and vertebral BMD and T-score, FRAX score and vertebral fractures (sVF) before (T0) and after 12 months (T12) of treatment were measured. MM, renal parameters, hypocalcemic episodes (HpCa), urinary tract infections (UTI), major graft and KTxps outcomes were monitored. The cohort was composed mainly of females, n = 21. We had 29 KTxps on steroid therapy and 22 KTxps on vitamin D supplementation. At T0, 25 and 7 KTxps had femoral osteoporosis (F-OPS) and osteopenia (F-OPS), respectively. Twenty-three and six KTxps had vertebral osteoporosis (V-OPS) and osteopenia (V-OPS), respectively. Seventeen KTxps had sVF. At T12, T-score increased at femoral and vertebral sites (p = 0.05, p = 0.008). The prevalence of F-OPS and V-OPS reduced from 78% to 69% and from 72% to 50%, respectively. Twenty-five KTxps ameliorated FRAX score and two KTxps had novel sVF. At T12, a slight reduction of Ca was present, without HpCa. Four KTxps had UTI. No graft rejections, loss of graft or deaths were reported. Our preliminary results show a good efficacy and safety of DB in KTxps. Longer and randomized studies involving more KTxps might elucidate the possible primary role of DB in the treatment of bone disorders in KTxps.

Bisphosphonates impair the onset of bone formation at remodeling sites

Bisphosphonates are widely used anti-osteoporotic drugs targeting osteoclasts. They strongly inhibit bone resorption, but also strongly reduce bone formation. This reduced formation is commonly ascribed to the mechanism maintaining the resorption/formation balance during remodeling. The present study provides evidence for an additional mechanism where bisphosphonates actually impair the onset of bone formation after resorption. The evidence is based on morphometric parameters recently developed to assess the activities reversing resorption to formation. Herein, we compare these parameters in cancellous bone of alendronate- and placebo-treated postmenopausal osteoporotic patients. Alendronate increases the prevalence of eroded surfaces characterized by reversal cells/osteoprogenitors at low cell density and remote from active bone surfaces. This indicates deficient cell expansion on eroded surfaces - an event that is indispensable to start formation. Furthermore, alendronate decreases the coverage of these eroded surfaces by remodeling compartment canopies, a putative source of reversal cells/osteoprogenitors. Finally, alendronate strongly decreases the activation frequency of bone formation, and decreases more the formative compared to the eroded surfaces. All these parameters correlate with each other. These observations lead to a model where bisphosphonates hamper the osteoprogenitor recruitment required to initiate bone formation. This effect results in a larger eroded surface, thereby explaining the well-known paradox that bisphosphonates strongly inhibit bone resorption without strongly decreasing eroded surfaces. The possible mechanism for hampered osteoprogenitor recruitment is discussed: bisphosphonates may decrease the release of osteogenic factors by the osteoclasts, and/or bisphosphonates released by osteoclasts may act directly on neighboring osteoprogenitor cells as reported in preclinical studies.

Managing Osteoporosis and Joint Damage in Patients with Rheumatoid Arthritis: An Overview

In rheumatoid arthritis, a representative systemic autoimmune disease, immune abnormality and accompanying persistent synovitis cause bone and cartilage destruction and systemic osteoporosis. Biologics targeting tumor necrosis factor, which plays a central role in the inflammatory process, and Janus kinase inhibitors have been introduced in the treatment of rheumatoid arthritis, making clinical remission a realistic treatment goal. These drugs can prevent structural damage to bone and cartilage. In addition, osteoporosis, caused by factors such as menopause, aging, immobility, and glucocorticoid use, can be treated with bisphosphonates and the anti-receptor activator of the nuclear factor-κB ligand antibody. An imbalance in the immune system in rheumatoid arthritis induces an imbalance in bone metabolism. However, osteoporosis and bone and cartilage destruction occur through totally different mechanisms. Understanding the mechanisms underlying osteoporosis and joint destruction in rheumatoid arthritis leads to improved care and the development of new treatments.

High Cortico-Trabecular Transitional Zone Porosity and Reduced Trabecular Density in Men and Women with Stress Fractures

To determine whether stress fractures are associated with bone microstructural deterioration we quantified distal radial and the unfractured distal tibia using high resolution peripheral quantitative computed tomography in 26 cases with lower limb stress fractures (15 males, 11 females; mean age 37.1 ± 3.1 years) and 62 age-matched healthy controls (24 males, 38 females; mean age 35.0 ± 1.6 years). Relative to controls, in men, at the distal radius, cases had smaller cortical cross sectional area (CSA) (p = 0.012), higher porosity of the outer transitional zone (OTZ) (p = 0.006), inner transitional zone (ITZ) (p = 0.043) and the compact-appearing cortex (CC) (p = 0.023) while trabecular vBMD was lower (p = 0.002). At the distal tibia, cases also had a smaller cortical CSA (p = 0.008). Cortical porosity was not higher, but trabecular vBMD was lower (p = 0.001). Relative to controls, in women, cases had higher distal radial porosity of the OTZ (p = 0.028), ITZ (p = 0.030) not CC (p = 0.054). Trabecular vBMD was lower (p = 0.041). Distal tibial porosity was higher in the OTZ (p = 0.035), ITZ (p = 0.009), not CC. Stress fractures are associated with compromised cortical and trabecular microstructure.

Comparative effectiveness of denosumab, teriparatide, and zoledronic acid among frail older adults: a retrospective cohort study

The comparative effects of zoledronic acid, denosumab, and teriparatide for preventing hip fractures in frail older adults, especially those in nursing homes, were unknown. We found that denosumab and zoledronic acid may be as effective as teriparatide for hip fracture prevention in nursing home residents.

INTRODUCTION

Several non-oral drugs exist for osteoporosis treatment, including zoledronic acid (ZA), denosumab, and teriparatide. Little data exist on the comparative effectiveness of these drugs for hip fracture prevention in frail older adults. We examined their comparative effectiveness in one of the frailest segments of the US population-nursing home (NH) residents.

METHODS

We conducted a national retrospective cohort study of NH residents aged ≥ 65 years using 2012 to 2016 national US Minimum Data Set clinical assessment data and linked Medicare claims. New parenteral ZA, denosumab, and teriparatide use was assessed via Medicare Parts B and D; hip fracture outcomes via Part A; and 125 covariates for confounding adjustment via several datasets. We used inverse probability weighted (IPW) competing risk regression models to compare hip fracture risk between groups with teriparatide as the reference.

RESULTS

The study cohort (N = 2019) included 1046 denosumab, 578 teriparatide, and 395 ZA initiators. Mean age was 85 years, 90% were female, and 68% had at least moderate functional impairment. Seventy-two residents (3.6%) had a hip fracture and 1100 (54.5%) died over a mean follow-up of 1.5 years. Compared to teriparatide use, denosumab use was associated with a 46% lower risk of hip fracture (HR 0.54, 95% CI 0.29-1.00) and no difference was observed for ZA (HR 0.70, 95% CI 0.26-1.85).

CONCLUSIONS

Denosumab and ZA may be as effective as teriparatide for hip fracture prevention in frail older adults. Given their lower cost and easier administration, denosumab and ZA are likely preferable non-oral treatments for most frail, older adults.

Hypocalcemia and bone mineral changes in hemodialysis patients with low bone mass treated with denosumab: a 2-year observational study

BACKGROUND

Increases in bone mineral density (BMD) following a single dose of denosumab and increased incidence of denosumab-associated acute hypocalcemia (DAAH) have been reported in chronic kidney disease (CKD) patients. Little is known about clinical risk factors related to DAAH and the long-term effect of denosumab on BMD in hemodialysis patients.

METHODS

An observational non-controlled study involving 47 hemodialysis patients was conducted to determine the independent risk factors related to percent changes in serum Ca levels associated with denosumab using multivariate regression analysis. Optimal predictive markers for DAAH were explored by receiver operating characteristic (ROC) analysis. Percent changes of BMD at the lumbar spine (LS) and femoral neck (FN) over 24 months were investigated.

RESULTS

The incidence of DAAH (serum corrected Ca (cCa) ≤ 8 mg/dL) following denosumab was 25.5%. Multivariate regression analysis showed baseline bone alkaline phosphatase (BAP) was independently related to percent changes in cCa levels (β = -0.407, P = 0.008). Tartrate-resistant acid phosphatase (TRACP-5b) was found to be the most accurate marker to predict DAAH with AUC of 0.750 (95% CI; 0.546-0.954, P = 0.02) and the optimal cut-off level was 670 mU/mL with sensitivity; 0.727 and specificity; 0.733. BMD significantly increased by 5.9 ± 1.7% (P = 0.01) at LS and 4.2 ± 1.5% (P = 0.04) at FN at 24 months.

CONCLUSION

In hemodialysis patients, high bone turnover was an independent risk factor for the Ca declines induced by denosumab. Denosumab significantly increased BMD at LS and FN over 24 months.

MRI-derived porosity index is associated with whole-bone stiffness and mineral density in human cadaveric femora

Ultrashort echo time (UTE) magnetic resonance imaging (MRI) measures proton signals in cortical bone from two distinct water pools, bound water, or water that is tightly bound to bone matrix, and pore water, or water that is freely moving in the pore spaces in bone. By isolating the signal contribution from the pore water pool, UTE biomarkers can directly quantify cortical bone porosity in vivo. The Porosity Index (PI) is one non-invasive, clinically viable UTE-derived technique that has shown strong associations in the tibia with μCT porosity and other UTE measures of bone water. However, the efficacy of the PI biomarker has never been examined in the proximal femur, which is the site of the most catastrophic osteoporotic fractures. Additionally, the loads experienced during a sideways fall are complex and the femoral neck is difficult to image with UTE, so the usefulness of the PI in the femur was unknown. Therefore, the aim of this study was to examine the relationships between the PI measure in the proximal cortical shaft of human cadaveric femora specimens compared to (1) QCT-derived bone mineral density (BMD) and (2) whole bone stiffness obtained from mechanical testing mimicking a sideways fall. Fifteen fresh, frozen whole cadaveric femora specimens (age 72.1 ± 15.0 years old, 10 male, 5 female) were scanned on a clinical 3-T MRI using a dual-echo UTE sequence. Specimens were then scanned on a clinical CT scanner to measure volumetric BMD (vBMD) and then non-destructively mechanically tested in a sideways fall configuration. The PI in the cortical shaft demonstrated strong correlations with bone stiffness (r = -0.82, P = 0.0014), CT-derived vBMD (r = -0.64, P = 0.0149), and with average cortical thickness (r = -0.60, P = 0.0180). Furthermore, a hierarchical regression showed that PI was a strong predictor of bone stiffness which was independent of the other parameters. The findings from this study validate the MRI-derived porosity index as a useful measure of whole-bone mechanical integrity and stiffness.

Cardiovascular Safety of Denosumab Across Multiple Indications: A Systematic Review and Meta-Analysis of Randomized Trials

The cardiovascular safety of denosumab has not yet been evaluated in a systematic review. This systematic review and meta-analysis sought to quantify the number of randomized controlled trials (RCTs) of denosumab (against comparators) reporting cardiovascular adverse events (CAEs) and examine the balance of CAEs between treatment arms. MEDLINE, Embase, and clinicaltrials.gov were searched from inception to October 26, 2019, for RCTs of denosumab versus comparators for any indication. Included trials were randomized, enrolled ≥100 participants, and reported bone-related outcomes. Primary outcome for analysis was all CAEs, a composite endpoint representing summation of all CAEs as reported by included trials. Secondary outcomes included major adverse cardiovascular events (MACE). Data were pooled using a fixed effects model to determine relative risk (RR) and 95% confidence interval (95% CI). Risk of bias was assessed using the Cochrane risk-of-bias tool. Of 554 records screened, 49 were included, while 36 reported CAEs. Twenty-seven included trials (12 eligible for meta-analysis) were conducted in 13,202 postmenopausal women. Compared with bisphosphonates, there was a 46% (95% CI 1.05 to 2.02) increase in CAEs (85/2136 events in denosumab-treated versus 58/2131 events in bisphosphonate-treated; seven trials). There was a similar imbalance in a five-point (stroke, myocardial infarction, cardiovascular death, heart failure, atrial fibrillation) MACE endpoint (28/2053 versus 12/2050; RR = 2.33 [1.19 to 4.56]). Compared with placebo-treated women, there was no imbalance in total CAEs (439/4725 events in denosumab versus 399/4467 in placebo; RR = 0.79 [0.41 to 1.52]; seven trials). No imbalance in total AEs (versus bisphosphonates: 0.98 [0.92 to 1.04]; versus placebo: 0.99 [0.98 to 1.01]) occurred. Other indications showed no statistically significant results. The excess CAEs in postmenopausal women treated with denosumab compared with bisphosphonates, but not placebo, indirectly supports claims that bisphosphonates may suppress CAEs. Future trials should use standardized CAE reporting to better describe cardiovascular effects of bone active medications. (PROSPERO: CRD42019135414.) © 2020 American Society for Bone and Mineral Research (ASBMR).

Exercise and Diet: Uncovering Prospective Mediators of Skeletal Fragility in Bone and Marrow Adipose Tissue

PURPOSE OF REVIEW

To highlight recent basic, translational, and clinical works demonstrating exercise and diet regulation of marrow adipose tissue (MAT) and bone and how this informs current understanding of the relationship between marrow adiposity and musculoskeletal health.

RECENT FINDINGS

Marrow adipocytes accumulate in the bone in the setting of not only hypercaloric intake (calorie excess; e.g., diet-induced obesity) but also with hypocaloric intake (calorie restriction; e.g., anorexia), despite the fact that these states affect bone differently. With hypercaloric intake, bone quantity is largely unaffected, whereas with hypocaloric intake, bone quantity and quality are greatly diminished. Voluntary running exercise in rodents was found to lower MAT and promote bone in eucaloric and hypercaloric states, while degrading bone in hypocaloric states, suggesting differential modulation of MAT and bone, dependent upon whole-body energy status. Energy status alters bone metabolism and bioenergetics via substrate availability or excess, which plays a key role in the response of bone and MAT to mechanical stimuli. Marrow adipose tissue (MAT) is a fat depot with a potential role in-as well as responsivity to-whole-body energy metabolism. Understanding the localized function of this depot in bone cell bioenergetics and substrate storage, principally in the exercised state, will aid to uncover putative therapeutic targets for skeletal fragility.

Bone Geometry, Density, and Microarchitecture in the Distal Radius and Tibia in Adults With Marfan Syndrome Assessed by HR-pQCT

Marfan syndrome (MFS) is a hereditary disorder of connective tissue caused by mutations in the fibrillin-1 gene. Studies have shown that patients with MFS have lower bone mass, but little is known about the other constituents of bone strength. We hypothesize that patients with MFS will have larger bone area and compromised cortical microarchitecture compared with non-MFS individuals. A total of 74 adult patients with MFS and 145 age- and sex-matched non-MFS reference individuals were included in this study. High-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius and distal tibia and dual-energy X-ray absorptiometry of total hip and the lumbar spine were performed, and bone turnover and sex hormones were measured. Patients with MFS had significantly lower areal bone mineral density (BMD) at the total spine (-13%) and total hip (-7%) when compared with the reference group. Patients with MFS had significantly larger total bone area at both the radius (+27%) and tibia (+34%). Volumetric BMD at both measured sites showed significantly reduced total, trabecular, and cortical volumetric BMD in patients with MFS compared with the reference group. The microarchitectural parameters at the radius and tibia were compromised in patients with MFS with significantly reduced trabecular number and thickness, leading to a higher trabecular separation and significantly reduced cortical thickness and increased cortical porosity compared with the reference group. The differences in bone density, geometry, or microarchitecture were not explained by increased bone turnover markers or circulating levels of sex hormones. We conclude patients with MFS have altered bone geometry, altered bone microstructure, and lower bone mass (lower areal BMD and volumetric BMD at all sites) compared with healthy reference individuals. Future studies should focus on fracture rates and fracture risk in adult and aging patients with MFS. © 2020 American Society for Bone and Mineral Research (ASBMR).

Comparing the Surgical Response of Bisphosphonate-Related Versus Denosumab-Related Osteonecrosis of the Jaws

PURPOSE

The pathophysiology and treatment of medication-related osteonecrosis of the jaws (MRONJ) remain unclear after nearly two decades of recorded observation and discussion. The purpose of this study was to assess outcomes of surgical resection of MRONJ in patients exposed to denosumab.

MATERIALS AND METHODS

A literature review was performed in conjunction with experts at the University of Illinois at Chicago Library. The primary outcome of interest was surgical success defined by maintenance of complete mucosal closure without bone exposure and infection after surgical resection. Secondary interests included demographics, MRONJ stage, location of the focus of osteonecrosis, and the primary underlying disease necessitating antiresorptive treatment. Statistical analysis was performed by χ², analysis of variance, or t test (P < .05 and b = 0.2 or a power of 0.8).

RESULTS

A total of 70 articles were identified and 14 met inclusion criteria. Twenty patients were included (13 women; 7 men); age 61.8 years ± 12.9 (range 19 to 77); and MRONJ stage I (40.0%), II (35.0%), and III (25.0%). Most cases occurred in the mandible (65.0%), followed by the maxilla (30.0%). The success rate of surgical intervention for MRONJ secondary to denosumab was in 16 of 20 (80.0%) patients. Stage I MRONJ lesions achieved mucosal closure in 100% of patients, stage II in 71.4%, and stage III in 60.0%. The surgical success rate was 83.3% in the maxilla and 76.9% in the mandible.

CONCLUSIONS

The surgical success rate for MRONJ secondary to denosumab was 80.0%, similar to that reported in bisphosphonates of 85 to 95%; however, more evidence must be reported and analyzed.

A single dose of zoledronate preserves bone mineral density for up to 2 years after a second course of romosozumab

This phase 2 study evaluated the efficacy and safety of transitioning to zoledronate following romosozumab treatment in postmenopausal women with low bone mass. A single dose of 5 mg zoledronate generally maintained the robust BMD gains accrued with romosozumab treatment and was well tolerated.

INTRODUCTION

Follow-on therapy with an antiresorptive agent is necessary to maintain the skeletal benefits of romosozumab therapy. We evaluated the use of zoledronate following romosozumab treatment.

METHODS

This phase 2, dose-finding study enrolled postmenopausal women with low bone mineral density (BMD). Subjects who received various romosozumab doses or placebo from months 0-24 were rerandomized to denosumab (60 mg SC Q6M) or placebo for 12 months, followed by open-label romosozumab (210 mg QM) for 12 months. At month 48, subjects who had received active treatment for 48 months were assigned to no further active treatment and all other subjects were assigned to zoledronate 5 mg IV. Efficacy (BMD, P1NP, and β-CTX) and safety were evaluated for 24 months, up to month 72.

RESULTS

A total of 141 subjects entered the month 48-72 period, with 51 in the no further active treatment group and 90 in the zoledronate group. In subjects receiving no further active treatment, lumbar spine (LS) BMD decreased by 10.8% from months 48-72 but remained 4.2% above the original baseline. In subjects receiving zoledronate, LS BMD was maintained (percentage changes: - 0.8% from months 48-72; 12.8% from months 0-72). Similar patterns were observed for proximal femur BMD in both groups. With no further active treatment, P1NP and β-CTX decreased but remained above baseline at month 72. Following zoledronate, P1NP and β-CTX levels initially decreased but approached baseline by month 72. No new safety signals were observed.

CONCLUSION

A zoledronate follow-on regimen can maintain robust BMD gains achieved with romosozumab treatment.

Denosumab in postmenopausal women with osteoporosis and diabetes: Subgroup analysis of FREEDOM and FREEDOM extension

PURPOSE

Diabetes and osteoporosis occur frequently in older adults and are both associated with increased fracture risk. Denosumab treatment reduced new vertebral, nonvertebral, and hip fractures over 3 years, with continued low fracture incidence for up to 10 years in postmenopausal women with osteoporosis. However, its effects in diabetic subjects with osteoporosis have not yet been investigated.

METHODS

Post hoc analysis of the 3-year, placebo-controlled FREEDOM study and 7-year Extension included postmenopausal women with osteoporosis and diabetes. Effects on BMD, vertebral, and nonvertebral fracture incidence were evaluated.

RESULTS

Of 7808 subjects in FREEDOM, 508 with diabetes received denosumab (n = 266) or placebo (n = 242). Among those, BMD increased significantly with denosumab versus placebo in FREEDOM, and continued to increase during the Extension in long-term (continuing denosumab) and crossover (placebo to denosumab) denosumab subjects. In FREEDOM, denosumab-treated subjects with diabetes had significantly lower new vertebral fracture rates (1.6%) versus placebo (8.0%) (RR: 0.20 [95% CI 0.07-0.61]; p = .001). Nonvertebral fracture incidence was higher with denosumab (11.7%) versus placebo (5.9%) (HR: 1.94 [95% CI 1.00-3.77]; p = .046), although there were fewer hip fractures with denosumab (World Health Organization, 2017 [1]) than placebo (4; nonsignificant). During the first 3 years in FREEDOM Extension, new vertebral and nonvertebral fracture incidences were low in long-term and crossover denosumab diabetic groups (≤6%), consistent with the overall Extension population; yearly nonvertebral fracture incidence was comparable to the FREEDOM placebo group.

CONCLUSION

Denosumab significantly increased BMD and decreased vertebral fracture risk in subjects with osteoporosis and diabetes. No reduction in nonvertebral fractures was observed.

The Pharmacologic Management of Osteoporosis in Primary Biliary Cholangitis: A Systematic Review and Meta-Analysis

INTRODUCTION

Osteoporosis is a common complication of primary biliary cholangitis (PBC) yet evidence for effective therapy is lacking. We sought to review all randomized controlled trials evaluating pharmacotherapy against placebo or no intervention for treatment of osteoporosis in PBC.

METHODOLOGY

A comprehensive database search was conducted from inception through 29 March 2017. The primary outcome was incidence of fractures; secondary outcomes were change in bone mineral density (BMD) and adverse events. We assessed studies for risk of bias, graded quality of evidence, and used meta-analysis to obtain overall effect by pooling studies of the same drug class.

RESULTS

We identified 11 randomized controlled trials evaluating bisphosphonates (3), hormone replacement therapy (2), ursodeoxycholic acid (1), obeticholic acid (1), cyclosporin A (1), vitamin K (1), calcitriol (1), and sodium fluoride (1). No intervention significantly reduced fractures compared to control. Although significant improvement in BMD was seen in one study with alendronate, a third-generation bisphosphonate, no significant improvement was seen on pooled analysis of all bisphosphonates including first-generation bisphosphonates (standard mean difference 0.41, p = 0.68). On pooled analysis, hormone replacement therapy modestly improved lumbar BMD (standard mean difference 0.69, p = 0.02), but with significantly increased adverse events (odds ratio 8.82, p = 0.01).

CONCLUSIONS

There is a lack of high-quality evidence supporting the efficacy of any treatment of osteoporosis in PBC. This may be explained by lack of power in the included studies. However, our current understanding of PBC-related osteoporosis indicates that it results from decreased bone formation, which may explain the attenuated effect of traditional antiresorptive agents. Future studies should investigate newer anabolic bone agents.

The therapeutic efficacy of denosumab for the loss of bone mineral density in glucocorticoid-induced osteoporosis: a meta-analysis

OBJECTIVE

Prevention of steroidal osteoporosis is an important issue. There is no clear consensus on the impact of anti-RANKL antibody (denosumab) on BMD in patients with glucocorticoid-induced osteoporosis (GIO). In this study, we aimed to evaluate the impact of denosumab on BMD loss in patients with GIO.

METHODS

A comprehensive systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. PubMed, Web of Science and Google Scholar were used to search for original studies reported about BMD in patients with GIO treated with denosumab. In meta-analysis of BMD, the mean difference in the rate of change from baseline and the 95% CI were calculated using the random effects model. The mean differences in patients treated with denosumab were compared with those in patients treated with bisphosphonates.

RESULTS

Out of 713 studies identified, seven studies met the selection criteria for the meta-analysis. At 6 and 12 months of denosumab therapy, increases in BMD were observed in the lumbar spine (2.99% [95% CI 2.71, 3.28] and 4.59% [95% CI 4.17, 5.01]), total hip (1.34% [95% CI 0.64, 2.04] and 2.16% [95% CI 2.05, 2.27]) and femoral neck (0.12% [95% CI -0.38, 0.62] and 1.55% [95% CI 0.45, 2.65]). Additionally, denosumab resulted in significant increases in BMD in the lumbar spine and femoral neck at 12 months compared with bisphosphonate therapy.

CONCLUSION

Patients with GIO experienced significant increases in BMD in response to treatment with denosumab that were detected in the lumbar spine, total hip and femoral neck at 12 months.

Bone Mineral Density After Transitioning From Denosumab to Alendronate

CONTEXT

There are few studies on patients transitioning from denosumab to bisphosphonates.

OBJECTIVE

To investigate patient characteristics and changes in bone mineral density (BMD) after transitioning from denosumab to alendronate.

DESIGN

Randomized, open-label, 2-year crossover Denosumab Adherence Preference Satisfaction (DAPS) study (NCT00518531).

SETTING

25 study centers in the US and Canada.

PATIENTS

Treatment-naïve postmenopausal women with BMD T-scores from -2.0 to -4.0.

INTERVENTIONS

This post hoc analysis evaluated women randomized to subcutaneous denosumab 60 mg every 6 months in year 1 followed by once-weekly oral alendronate 70 mg in year 2.

MAIN OUTCOME MEASURE

A 3% BMD threshold identified participants who lost, maintained, or gained BMD in year 2 on alendronate.

RESULTS

Of 126 participants randomized to denosumab, 115 (91%) transitioned to alendronate in year 2. BMD increased by 3% to 6% with denosumab in year 1 and by 0% to 1% with alendronate in year 2. After transitioning to alendronate, most participants maintained or increased BMD; 15.9%, 7.6%, and 21.7% lost BMD at the lumbar spine, total hip, and femoral neck, respectively. Few participants fell below their pretreatment baseline BMD value; this occurred most often in those who lost BMD in year 2. Women who lost BMD with alendronate in year 2 also showed a greater percent change in BMD with denosumab in year 1. The BMD change in year 2 was similar regardless of baseline characteristics or adherence to oral alendronate.

CONCLUSION

Alendronate can effectively maintain the BMD gains accrued after 1 year of denosumab in most patients, regardless of baseline characteristics.

Effect of Denosumab on Bone Mineral Density of Hematopoietic Stem Cell Transplantation Recipients

PURPOSE

Denosumab is a monoclonal antibody that prevents the development of osteoclasts. The effect of denosumab in solid organ transplant recipients has been elucidated, but its effect in haematopoietic stem cell transplantation recipients has not been studied yet. The aim of this study was to determine the effectiveness and safety of denosumab in haematopoietic stem cell transplantation recipients.

METHODS

We retrospectively evaluated 33 female patients with osteoporosis (mean age 52.6 ± 9.8 years) following allogeneic haematopoietic stem cell transplantation. Patients were treated with denosumab every 6 months for 12 months. Changes in bone mineral density were evaluated for denosumab-treated patients in a 12-month interval after the first administration of denosumab.

RESULTS

Significant increases in bone mineral density were observed in all measured skeletal sites including 4.39 ± 6.63% in the lumbar spine (p=0.014), 3.11 ± 7.69% in the femoral neck (p=0.048), and 1.97 ± 6.01% in the total hip (p=0.138). The bone turnover marker serum cross-linked C-terminal telopeptide of type 1 collagen was decreased at 18 months (-51.6 ± 17.6%, p < 0.001). No serious symptomatic hypocalcaemia was observed. Serious adverse drug reactions requiring drug discontinuation were not observed.

CONCLUSION

Denosumab improved bone mineral density in haematopoietic stem cell transplantation recipients. The use of denosumab could be a good therapeutic option without causing severe adverse effects in recipients of haematopoietic transplantation.

Long-term denosumab treatment restores cortical bone loss and reduces fracture risk at the forearm and humerus: analyses from the FREEDOM Extension cross-over group

Upper limb fractures (including wrist, forearm, and humerus) represent a significant burden among postmenopausal women with osteoporosis. Up to 7 years of treatment with denosumab resulted in an increase in bone mineral density and decrease in fractures in upper limb sites.

INTRODUCTION

Upper limb (wrist, forearm, and humerus) fractures are a significant burden in osteoporosis, associated with significant morbidity and mortality. Denosumab, a monoclonal antibody against RANK ligand, increases bone mineral density (BMD) and decreases vertebral, nonvertebral, and hip fractures. Here, we evaluated the long-term effect of denosumab treatment on upper limb fracture risk and BMD.

METHODS

In the FREEDOM trial, subjects were randomized 1:1 to receive every-6-month denosumab 60 mg or placebo subcutaneously for 3 years, after which all subjects could receive denosumab for up to 7 years (Extension). Among placebo subjects who completed FREEDOM and enrolled in the Extension, wrist, forearm, humerus, and upper limb fracture rates and rate ratios between different time periods (FREEDOM years 1-3, Extension years 1-3, and Extension years 4-7) were computed. BMD at the ultradistal radius, 1/3 radius, and total radius was analyzed in a subset of subjects in a BMD substudy.

RESULTS

This analysis included 2207 subjects (116 in the BMD substudy). Fracture rates decreased over the 7-year Extension; fracture rate ratios between Extension years 4-7 (denosumab) and FREEDOM years 1-3 (placebo) reduced significantly for the wrist (0.57), forearm (0.57), humerus (0.42), and upper limb (0.52; p < 0.05 for all). Percentage increase in BMD from Extension baseline at the ultradistal radius, 1/3 radius, and total radius was significant by Extension year 7 (p < 0.05 for all).

CONCLUSIONS

Long-term treatment with denosumab decreases upper limb fracture risk and increases forearm BMD, suggesting beneficial effects on both cortical and trabecular bone accruing over time.

Predictive factors for the efficacy of denosumab in postmenopausal Japanese women with non-metastatic breast cancer receiving adjuvant aromatase inhibitors: a combined analysis of two prospective clinical trials

Aromatase inhibitors (AIs) are the gold standard therapy for breast cancer in postmenopausal women. AI suppresses the conversion of androgens to estrogens; however, this results in osteopenia, osteoporosis, and bone fracture, thus reducing the patient's quality of life. The use of adjuvant denosumab reduces the risk of clinical fractures in postmenopausal patients with breast cancer receiving AI. However, the efficacy of denosumab in the treatment of AI-associated bone loss has not been prospectively evaluated in Japan. In this study, we aimed to investigate the predictive factors for the efficacy of denosumab in postmenopausal patients with breast cancer treated with AI by analyzing the results of two prospective trials. The patients received 60 mg denosumab subcutaneously every 6 months. The primary endpoint was percentage change in lumbar spine bone mineral density (BMD) from baseline to month 12 in lumbar spine. Post hoc analysis and T tests were performed. A total of 205 patients were enrolled. At 12 and 24 months, the lumbar spine BMD increased by 5.6% [95% confidence interval (CI) 4.9-6.3] and 8.3% (95% CI 7.5-9.1), respectively. Subgroup analysis was conducted according to the time of AI therapy initiation, type of AI therapy, age, time since menopause, baseline body mass index, and BMD. The results showed that baseline lumbar and left femoral BMD was significantly associated with a percentage change in these sites, respectively. In addition, baseline left femoral BMD was also associated with a change in lumbar BMD. In conclusion, the baseline BMD in the lumbar spine was a predictive indicator for the efficacy of denosumab in this site and the baseline BMD in left femoral neck was a predictive indicator in lumbar spine and left femur.

Effect of Denosumab on Femoral Periprosthetic BMD and Early Femoral Stem Subsidence in Postmenopausal Women Undergoing Cementless Total Hip Arthroplasty

Antiresorptive denosumab is known to improve the quality and strength of cortical bone in the proximal femurs of osteoporotic women, but its efficacy in preventing periprosthetic bone loss and reducing femoral stem migration has not been studied in women undergoing cementless total hip arthroplasty. We conducted a single-center, randomized, double-blinded, placebo-controlled trial of 65 postmenopausal women with primary hip osteoarthritis and Dorr type A or B proximal femur anatomy. The patients randomly received subcutaneous injections of denosumab 60 mg or placebo once every 6 months for 12 months, starting 1 month before surgery. The primary endpoint was the change in bone mineral density (BMD) of the proximal femur (Gruen zone 7) at week 48, and the secondary endpoint was stem subsidence measured by radiostereometric analysis (RSA) at week 48. Exploratory endpoints included changes in BMDs of the contralateral hip, lumbar spine and distal radius, serum levels of bone turnover markers, walking speed, walking activity, patient-reported outcome measures, and radiographic assessment of stem osseointegration. The participants underwent vertebral-fracture assessment in an extension safety study at 3 years. Denosumab significantly decreased bone loss in the medial femoral neck (zone 7) and increased periprosthetic BMD in the greater trochanteric region (zone 1) and lesser trochanteric region (zone 6). Denosumab did not reduce temporary femoral stem migration. The migration occurred mainly during the settling period (0 to 12 weeks) after implantation of the prosthesis. All of the stems osseointegrated, as evaluated by RSA and radiographs. There were no intergroup differences in functional recovery. Discontinuation of denosumab did not lead to any adverse events. In conclusion, denosumab increased periprosthetic BMD in the clinically relevant regions of the proximal femur, but the treatment response was not associated with any reduction of initial stem migration. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Different effects of Wnt/β-catenin activation and parathyroid hormone on diaphyseal and metaphyseal in the early phase of femur bone healing of mice

Parathyroid hormone (PTH) and agents related to the manipulation of Wnt/β-catenin signalling are two promising anabolic anti-osteoporotic therapies that have been shown to promote the healing of bone fractures. Now, it is widely accepted that cortical bone and trabecular bone are two different compartments, and should be treated as separate compartments in pathological processes, such as fracture healing. It is currently unknown whether PTH and the activation of β-catenin signalling would demonstrate different effects on cortical bone and trabecular bone healing. In the current study, single 0.6-mm cortex holes were made in the femur metaphysis and diaphysis of mice, and then, PTH application and β-catenin activation were used to observe the promoting effect on bone healing. The effects of β-catenin and PTH signalling on fracture healing were observed by X-ray and CT at 3, 6, and 14 days after fracture, and the levels of β-catenin were detected by RT-PCR assay, and the number of specific antigen-positive cells of BRDU, OCN, RUNX2 was counted by immunohistochemical staining. While β-catenin activation and PTH were found to demonstrate similar effects on accelerating metaphyseal bone healing, activation of β-catenin showed a more striking effect than PTH on promoting diaphyseal bone healing. These findings might be helpful for selecting proper medication to accelerate fracture healing of different bone compartments.

Reduction of Cortical Bone Turnover and Erosion Depth After 2 and 3 Years of Denosumab: Iliac Bone Histomorphometry in the FREEDOM Trial

Denosumab, a RANKL inhibitor, reduced the risk of vertebral, hip, and nonvertebral fractures in the Fracture REduction Evaluation of Denosumab in Osteoporosis every 6 Months (FREEDOM) trial of postmenopausal women with osteoporosis compared with placebo. Previous bone histomorphometric analysis in FREEDOM showed decreased bone resorption and turnover in cancellous bone after 2 and 3 years. The purpose of the present study was to evaluate the effects of denosumab compared with placebo in the cortical compartment from transiliac bone biopsies obtained during FREEDOM. A total of 112 specimens were evaluable for cortical histomorphometry, including 67 obtained at month 24 (37 placebo, 30 denosumab) and 45 at month 36 (25 placebo, 20 denosumab). Eroded surface, osteoclast surface, erosion depth, and wall thickness were measured on the endocortical surface. Cortical thickness and cortical porosity were also measured. Dynamic parameters of bone formation were assessed for endocortical, periosteal, and intracortical envelopes. Endocortical osteoclast surface, eroded surface, and mean and maximum erosion depth were significantly lower in the denosumab group versus placebo at months 24 and 36 (p < 0.0001 to p = 0.04). Endocortical wall thickness and intracortical measures (cortical porosity and cortical thickness) were not different between the two groups. Dynamic parameters were low with tetracycline labels in cortical bone observed in 13 (43%) and 10 (50%) of denosumab biopsies at months 24 and 36, respectively, reflecting a marked decrease in bone turnover. In conclusion, our data reveal the mechanism of action of denosumab on cortical bone: inhibition of osteoclastic resorption and reduced activation of new remodeling sites. In addition, reduced endocortical erosion depth with no change of wall thickness may contribute to increased bone strength by reducing the bone loss and fragility associated with deep resorption cavities and may likely contribute to the greater BMD gain with denosumab than with other antiresorptive agents. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Efficacy and safety of denosumab compared to bisphosphonates in improving bone strength in postmenopausal osteoporosis: a systematic review

INTRODUCTION

Osteoporosis is the main cause of fractures among women after menopause. This study aimed to evaluate the efficacy and safety of denosumab compared to bisphosphonates in treating postmenopausal osteoporosis.

METHODS

Databases including PubMed and the Cochrane Central Register of Controlled Trials were systematically searched for randomised controlled trials (RCTs) that directly compared denosumab and bisphosphonates. RCTs that studied both denosumab and bisphosphonates in postmenopausal women with osteoporosis and had a Jadad score ≥ 3 were included.

RESULTS

Nine studies were eligible for inclusion. They were further categorised into six cohort groups. All studies had denosumab with oral bisphosphonates as the active comparator. Four out of six cohort studies showed significant improvements in bone strength (p < 0.001) at the distal radius, tibia, total hip, femoral neck, lumbar spine and trochanter at 12 months for patients on denosumab compared to the bisphosphonate group. Serum C-telopeptide of cross-linked collagen, a bone turnover marker, was consistently lower in the denosumab group in all studies. There were no significant differences in hypocalcaemia, atypical fractures, fragility fractures, osteonecrosis of the jaw, all infections (including fever or influenza-like symptoms), gastrointestinal side effects or dermatological conditions in all studies, except for one that did not document side effects.

CONCLUSION

Denosumab can be used both as a first-line agent and an alternative to bisphosphonate in the treatment of postmenopausal osteoporosis. There is currently insufficient data to show that denosumab is not inferior to bisphosphonates in fracture prevention.

A network of trans-cortical capillaries as mainstay for blood circulation in long bones

Closed circulatory systems (CCS) underlie the function of vertebrate organs, but in long bones their structure is unclear, although they constitute the exit route for bone marrow (BM) leukocytes. To understand neutrophil emigration from BM, we studied the vascular system of murine long bones. Here we show that hundreds of capillaries originate in BM, cross murine cortical bone perpendicularly along the shaft and connect to the periosteal circulation. Structures similar to these trans-cortical-vessels (TCVs) also exist in human limb bones. TCVs express arterial or venous markers and transport neutrophils. Furthermore, over 80% arterial and 59% venous blood passes through TCVs. Genetic and drug-mediated modulation of osteoclast count and activity leads to substantial changes in TCV numbers. In a murine model of chronic arthritic bone inflammation, new TCVs develop within weeks. Our data indicate that TCVs are a central component of the CCS in long bones and may represent an important route for immune cell export from the BM.

Osteoporosis

Fractures resulting from osteoporosis become increasingly common in women after age 55 years and men after age 65 years, resulting in substantial bone-associated morbidities, and increased mortality and health-care costs. Research advances have led to a more accurate assessment of fracture risk and have increased the range of therapeutic options available to prevent fractures. Fracture risk algorithms that combine clinical risk factors and bone mineral density are now widely used in clinical practice to target high-risk individuals for treatment. The discovery of key pathways regulating bone resorption and formation has identified new approaches to treatment with distinctive mechanisms of action. Osteoporosis is a chronic condition and long-term, sometimes lifelong, management is required. In individuals at high risk of fracture, the benefit versus risk profile is likely to be favourable for up to 10 years of treatment with bisphosphonates or denosumab. In people at a very high or imminent risk of fracture, therapy with teriparatide or abaloparatide should be considered; however, since treatment duration with these drugs is restricted to 18-24 months, treatment should be continued with an antiresorptive drug. Individuals at high risk of fractures do not receive adequate treatment and strategies to address this treatment gap-eg, widespread implementation of Fracture Liaison Services and improvement of adherence to therapy-are important challenges for the future.

Effects of osteoporosis drug treatments on cortical and trabecular bone in the femur using DXA-based 3D modeling

Effects of osteoporosis drugs on proximal femur cortical and trabecular bone were studied using dual-energy x-ray absorptiometry (DXA)-based 3D modeling method. Changes observed in this head-to-head study were consistent with those obtained using computed tomography in the literature.

INTRODUCTION

The aim of the present study was to assess the effects of osteoporosis drugs on cortical and trabecular bone at the proximal femur using DXA-based 3D modeling.

METHODS

We retrospectively analyzed 155 patients stratified by treatments: naive of treatment (NAIVE), alendronate (AL), denosumab (DMAB), and teriparatide (TPTD). DXA scans were performed at baseline and after treatment, and areal bone mineral density at spine and femur were measured. A software algorithm (3D-SHAPER) was used to derive 3D models from hip DXA scans and compute: trabecular and cortical volumetric BMD (vBMD), cortical thickness (Cth), and cortical surface BMD (cortical sBMD). Changes from baseline were normalized at 24 months and evaluated in terms or percentage.

RESULTS

After 24 months, a non-significant decrease was observed for trabecular vBMD, Cortical sBMD, Cth, and cortical vBMD (- 2.3, - 0.8, - 0.3, and - 0.5%) in the NAIVE group. Under AL and DMAB, significant increases were observed in trabecular vBMD (3.8 and 7.3%), cortical vBMD (1.4 and 2.0%), and cortical sBMD (1.5 and 3.6%). An increase in Cth was observed in patients under DMAB (1.8%). Under TPTD, a significant increase in Trabecular vBMD was observed (5.9%) associated with a non-significant increase of Cth (+ 1%) concomitant with a decrease in cortical vBMD (- 1.1%).

CONCLUSION

Results obtained in this head-to-head study are consistent with those obtained using computed tomography in the literature. DXA-based modeling techniques could complement standard DXA examination to monitor treatment effects on trabecular and cortical compartments.

Advances and Unmet Needs in the Therapeutics of Bone Fragility

The prevalence of fragility fractures increases as longevity increases the proportion of the elderly in the community. Until recently, the majority of studies have targeted women with osteoporosis defined as a bone mineral density (BMD) T score of < -2.5 SD, despite evidence that the population burden of fractures arises from women with osteopenia. Antiresorptive agents reduce vertebral and hip fracture risk by ~50 percent during 3 years but efficacy against non-vertebral fractures, 80% of all fractures in the community, is reported in few studies, and of those, the risk reduction is only 20-30%. Recent advances in the use of antiresorptives and anabolic agents has addressed some of these unmet needs. Zoledronic acid is now reported to reduce vertebral and non-vertebral fractures rates in women with osteopenia. Studies using teriparatide demonstrate better vertebral and clinical (symptomatic vertebral and non-vertebral) antifracture efficacy than risedronate. Abaloparatide, a peptide sharing amino acid sequences with teriparatide, reduces vertebral and non-vertebral fractures. Romosozumab, a monoclonal antibody suppressing sclerostin, reduces vertebral and non-vertebral fractures within a year of starting treatment, and does so more greatly than alendronate. Some recent studies signal undesirable effects of therapy but provide essential cautionary insights into long term management. Cessation of denosumab is associated with a rapid increase in bone remodeling and the uncommon but clinically important observation of increased multiple vertebral fractures suggesting the need to start alternative anti-resorptive therapy around the time of stopping denosumab. Antiresorptives like bisphosphonates and denosumab suppress remodeling but not completely. Antifracture efficacy may be limited, in part, as a consequence of continued unsuppressed remodeling, particularly in cortical bone. Bisphosphonates may not distribute in deeper cortical bone, so unbalanced intracortical remodeling continues to cause microstructural deterioration. In addition, suppressed remodeling may compromise the material composition by increasing matrix mineral density and glycosylation of collagen. As antiresorptive agents do not restore microstructural deterioration existing at the time of starting treatment, under some circumstances, anabolic therapy may be more appropriate first line treatment. Combining antiresorptive and anabolic therapy is an alternative but whether anti-fracture efficacy is greater than that achieved by either treatment alone is not known.