Abaloparatide-SC improves trabecular microarchitecture as assessed by trabecular bone score (TBS): a 24-week randomized clinical trial

Comparing musculoskeletal and connective tissue disorder risks of teriparatide and abaloparatide in osteoporosis: an analysis based on FDA adverse event reporting system (FAERS)

BACKGROUND

Osteoporosis (OP), characterized by low bone mass and increased fracture risk, is a prevalent skeletal disorder. Teriparatide (TP) and abaloparatide (ABL) are anabolic agents that may reduce fracture incidence, but their impact on musculoskeletal and connective tissue disorders (MCTD) risk is uncertain.

RESEARCH DESIGN AND METHODS

A retrospective, observational disproportionality analysis was conducted utilizing FAERS data from Q1 2004 to Q3 2023, where TP or ABL was identified as the primary suspect drug. Multiple data mining algorithms, including reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN), and multi-item gamma Poisson shrinker (MGPS), were employed to detect MCTD safety signals.

RESULTS

A total of 366,747 TP-related and 422,377 ABL-related cases were identified, predominantly among female patients aged ≥45 years. The top specific AEs involved musculoskeletal, connective tissue, and administration site disorders. Comparative analysis revealed a higher frequency of AEs related to the nervous, cardiovascular, and gastrointestinal systems for ABL compared to TP. Both drugs exhibited strong signals for arthralgia, limb pain, back pain, muscle spasms, bone pain, muscle pain, and muscle weakness.

CONCLUSION

The analysis suggests a potential MCTD risk with TP and ABL treatment in OP patients, highlighting the need for AE monitoring and management in clinical practice. This contributes to a better understanding of the safety profiles of these anabolic medications.

Romosozumab versus parathyroid hormone receptor agonists: which osteoanabolic to choose and when?

Osteoanabolic agents are used as a first line treatment in patients at high fracture risk. The PTH receptor 1 (PTH1R) agonists teriparatide (TPTD) and abaloparatide (ABL) increase bone formation, bone mineral density (BMD), and bone strength by activating PTH receptors on osteoblasts. Romosozumab (ROMO), a humanized monoclonal antibody against sclerostin, dramatically but transiently stimulates bone formation and persistently reduces bone resorption. Osteoanabolic agents increase BMD and bone strength while being more effective than antiresorptives in reducing fracture risk in postmenopausal women. However, direct comparisons of the antifracture benefits of osteoanabolic therapies are limited. In a direct comparison of TPTD and ABL, the latter resulted in greater BMD increases at the hip. While no differences in vertebral or non-vertebral fracture risk were observed between the two drugs, ABL led to a greater reduction of major osteoporotic fractures. Adverse event profiles were similar between the two agents except for hypercalcemia, which occurred more often with TPTD. No direct comparisons of fracture risk reduction between ROMO and the PTH1R agonists exist. Individual studies have shown greater increases in BMD and bone strength with ROMO compared with TPTD in treatment-naive women and in women previously treated with bisphosphonates. Some safety aspects, such as a history of tumor precluding the use of PTH1R agonists, and a history of major cardiovascular events precluding the use of ROMO, should also be considered when choosing between these agents. Finally, convenience of administration, reimbursement by national health systems and length of clinical experience may influence patient choice.

Proton Pump Inhibitor Use and Bone Health in Patients With Rheumatic Diseases: A Cross-Sectional Study

OBJECTIVE

To assess the effect of proton pump inhibitor (PPI) use on bone mineral density (BMD) and bone microarchitecture as measured by the trabecular bone score (TBS) in patients with inflammatory rheumatic and musculoskeletal diseases (iRMDs).

METHODS

Cross-sectional data from a prospective single-center cohort (2015 to 2022) of patients with iRMDs were used to evaluate 3 co-primary outcomes: BMD of the left femoral neck and the lumbar spine (as T-scores) and the TBS. Inverse probability weighting adjusted for numerous confounders including age, sex, body mass index, current and cumulative glucocorticoid (GC) dose, C-reactive protein levels, disability, and others. Analyses were based on general linear models, following a prespecified statistical analysis plan.

RESULTS

The study included 1495 patients (75% women; mean age, 62.6±13.1 years; 49% and 63% with regular PPI and GC use, respectively). The PPI users had lower BMD at both spine (adjusted contrast -0.25; 95% CI, -0.47 to -0.04; P=.02) and femoral neck (-0.17 [-0.35 to 0.01]; P=.07). Differences between PPI users and nonusers were statistically significant only in patients concurrently using GCs at more than 7.5 mg/d prednisone equivalent. The TBS was similar in PPI users and nonusers (adjusted contrast, 0.00 [-0.04 to 0.04]; P=.97).

CONCLUSION

Our results suggest that PPIs lead to a loss of BMD rather than an impairment of bone microarchitecture in patients with iRMDs. The negative association between PPI use and BMD appears to be dependent on concurrent GC use. Clinicians should carefully review the indication for PPI use in patients with iRMDs, especially in those receiving higher dose GCs.

Update on the utility of trabecular bone score (TBS) in clinical practice for the management of osteoporosis: a systematic review by the Egyptian Academy of Bone and Muscle Health

Trabecular bone score (TBS) is a grayscale textural assessment resulting from a computed evaluation of pixel gray-level variations in previously obtained lumbar spine DXA images. It is an index of bone microarchitecture correlated with parameters of bone strength. Higher values of TBS indicate a better microarchitecture, whereas lower values indicate a degraded microarchitecture. TBS can be used alongside Fracture Risk Assessment tool “FRAX” and bone mineral density (BMD) to enhance the assessment of fracture risk and to inform treatment initiation and monitoring. A systematic review was carried out aiming to update the evidence on the clinical use of the TBS in the management of both primary and secondary osteoporosis. Results revealed that in both primary and secondary osteoporosis, TBS enhances the prediction of fracture risk, and when adjust with BMD and clinical risk factors, it is able to inform the decision-making process regarding initiating osteoporosis therapy and the choice of anti-osteoporosis medication. Evidence also implies that TBS provides valuable adjunctive information in monitoring osteoporosis therapy. In conclusion, this work provides an up-to-date evidence-based review and recommendations which informs the utility of trabecular bone score in standard clinical practice.

Targeted Delivery of Abaloparatide to Spinal Fusion Site Accelerates Fusion Process in Rats

Spinal fusions are performed to treat congenital skeletal malformations, spondylosis, degenerative disk diseases, and other pathologies of the vertebrae that can be resolved by reducing motion between neighboring vertebrae. Unfortunately, up to 100,000 fusion procedures fail per year in the United States, suggesting that efforts to develop new approaches to improve spinal fusions are justified. We have explored whether the use of an osteotropic oligopeptide to target an attached bone anabolic agent to the fusion site might be exploited to both accelerate the mineralization process and improve the overall success rate of spinal fusions. The data presented below demonstrate that subcutaneous administration of a modified abaloparatide conjugated to 20 mer of D-glutamic acid not only localizes at the spinal fusion site but also outperforms the standard of care (topically applied BMP2) in both speed of mineralization (p < 0.05) and overall fusion success rate (p < 0.05) in a posterior lateral spinal fusion model in male and female rats, with no accompanying ectopic mineralization. Because the bone-localizing conjugate can be administered ad libitum post-surgery, and since the procedure appears to improve on standard of care, we conclude that administration of a bone-homing anabolic agent for improvement of spinal fusion surgeries warrants further exploration.

Response rates for lumbar spine, total hip, and femoral neck bone mineral density in men treated with abaloparatide: results from the ATOM study

Osteoporosis in men is an underappreciated public health issue, accounting for approximately 30% of the societal burden of osteoporosis. Although the prevalence of osteoporosis in men is lower, fracture-related morbidity and mortality rates exceed those of women. Abaloparatide is a synthetic, 34-amino acid peptide with homology to human parathyroid hormone-related protein (PTHrP), which favors bone formation by selective activation of PTH receptor type 1. In the Abaloparatide for the Treatment of Men With Osteoporosis (ATOM; NCT03512262) trial, 228 men with primary or hypogonadism-associated osteoporosis were randomized to receive subcutaneous injections of abaloparatide 80 μg or placebo. Abaloparatide significantly improved LS, TH, and FN BMD when compared with placebo. In this prespecified analysis, the proportion of men with a percent change from baseline of >0%, >3%, and > 6% in BMD at the LS, TH, and FN at 3, 6, and 12 mo and/or a shift in T-score category (based on LS and TH T-scores) at 12 mo was compared between the abaloparatide and placebo groups in ATOM. There were significantly more men with a BMD gain of >3% at all 3 anatomical sites in the abaloparatide than placebo group at month 6 (18/122 [14.8%] vs 1/70 [1.4%], P = .002) and at month 12 (38/119 [31.9%] vs 1/66 [1.5%], P < .0001). At month 3, more men treated with abaloparatide than placebo had a > 3% BMD increase at the LS (82/134 [61.2%] vs 21/68 [30.9%], P < .0001). A greater proportion of men treated with abaloparatide had an improvement in T-score category from osteoporosis to low BMD or normal when compared with placebo. In conclusion, use of abaloparatide compared with placebo for 12 mo resulted in significant and rapid improvements in BMD in men with osteoporosis from the ATOM study.

Sequential Therapy for the Long-Term Treatment of Postmenopausal Osteoporosis

Osteoporosis is a chronic condition characterized by decreased bone mass, loss of skeletal integrity, and increased susceptibility to fracture. Drugs used to treat osteoporosis can be classified as those that block bone resorption (antiresorptive), stimulate bone formation (anabolic), or do both. While all currently approved medications reduce the risk of fragility fractures in high-risk populations, they are generally unable to fully restore bone strength in most patients with established disease. Thus, the majority of patients require disease management over many years. Unfortunately, the continuous use of a single drug has limitations, both in terms of efficacy and safety, and so sequential therapy is commonly required. Given the expanding list of pharmacological agents currently available, careful consideration needs to be given as to which drugs to use and in what sequence. This review will evaluate the differential effects of antiresorptive, bone-forming, and dual-acting drugs when used in specific sequences and will explore the current evidence favoring the initial use of bone-forming/dual-acting drugs followed by antiresorptive medications. This review will also examine the notion that long-term treatment with an antiresorptive drug may diminish the efficacy of subsequent treatment with a bone-forming/dual-acting drug. Finally, this review will explore the current evidence pertaining to the specific issue of how to best prevent the clinical ramifications of denosumab cessation.

Clinical Use of Trabecular Bone Score: The 2023 ISCD Official Positions

Osteoporosis can currently be diagnosed by applying the WHO classification to bone mineral density (BMD) assessed by dual-energy x-ray absorptiometry (DXA). However, skeletal factors other than BMD contribute to bone strength and fracture risk. Lumbar spine TBS, a grey-level texture measure which is derived from DXA images has been extensively studied, enhances fracture prediction independent of BMD and can be used to adjust fracture probability from FRAX® to improve risk stratification. The purpose of this International Society for Clinical Densitometry task force was to review the existing evidence and develop recommendations to assist clinicians regarding when and how to perform, report and utilize TBS. Our review concluded that TBS is most likely to alter clinical management in patients aged ≥ 40 years who are close to the pharmacologic intervention threshold by FRAX. The TBS value from L1-L4 vertebral levels, without vertebral exclusions, should be used to calculate adjusted FRAX probabilities. L1-L4 vertebral levels can be used in the presence of degenerative changes and lumbar compression fractures. It is recommended not to report TBS if extreme structural or pathological artifacts are present. Monitoring and reporting TBS change is unlikely to be helpful with the current version of the TBS algorithm. The next version of TBS software will include an adjustment based upon directly measured tissue thickness. This is expected to improve performance and address some of the technical factors that affect the current algorithm which may require modifications to these Official Positions as experience is acquired with this new algorithm.

Romosozumab is associated with greater trabecular bone score improvement compared to denosumab in postmenopausal osteoporosis

In this study, romosozumab demonstrated significantly greater improvement in trabecular bone score compared to denosumab therapy in postmenopausal women previously treated with antiresorptive agents. Notably, in patients previously treated with anti-resorptive agents, treatment with romosozumab resulted in similar increases in trabecular bone score compared to that of drug-naïve patients.

PURPOSE

Romosozumab significantly increases bone mineral density (BMD) and rapidly reduces fracture risk. Whether romosozumab can improve the spinal trabecular bone score (TBS) as a bone quality indicator merits further investigation.

METHODS

Data for postmenopausal women starting romosozumab or denosumab treatment at Severance Hospital, Korea, were analyzed. Romosozumab and denosumab groups were 1:1 matched using propensity scores, considering relevant covariates. Good responders were defined as those with TBS improvement of 5.8% or greater.

RESULTS

Overall, 174 patients (romosozumab, n = 87; denosumab, n = 87) were analyzed. Matched groups did not differ in age (64 years), weight, height, previous fracture (38%), lumbar spine or femoral neck BMD (T-score, -3.4 and -2.6, respectively), or prior bisphosphonate or selective estrogen receptor modulator (SERM) exposure (50%). The romosozumab group exhibited a greater increase in lumbar spine BMD (15.2% vs. 6.9%, p < 0.001) and TBS (3.7% vs. 1.7%, p = 0.013) than the denosumab group. In patients transitioning from bisphosphonate or SERM, romosozumab users showed greater improvement in TBS compared to denosumab users (3.9% versus 0.8%, P = 0.006); the drug-naive group showed no significant difference (3.6% versus 2.7%, P = 0.472). The romosozumab group had a higher proportion of good responders than the denosumab group (33.3% vs. 18.4%, p = 0.024). Romosozumab therapy for 12 months resulted in 3.8-fold higher odds of a good response in TBS than denosumab after covariate adjustment (adjusted odds ratio 3.85, p = 0.002).

CONCLUSION

Romosozumab could improve bone mass and bone quality, measured by TBS, in postmenopausal osteoporosis, particularly as a subsequent regimen in patients previously taking anti-resorptive agents.

MRI-based vertebral bone quality score: relationship with age and reproducibility

Vertebral bone quality (VBQ) score is an opportunistic measure of bone mineral density using routine preoperative MRI in spine surgery. VBQ score positively correlates with age and is reproducible across serial scans. However, extrinsic factors, including MRI machine and protocol, affect the VBQ score and must be standardized.

PURPOSE

The purposes of this study were to determine whether VBQ score increased with age and whether VBQ remained consistent across serial MRI studies obtained within 3 months.

METHODS

This retrospective study evaluated 136 patients, age 20-69, who received two T1-weighted lumbar MRI within 3 months of each other between January 2011 and December 2021. VBQ(L1-4) score was calculated as the quotient of L1-L4 signal intensity (SI) and L3 cerebral spinal fluid (CSF) SI. VBQ(L1) score was calculated as the quotient of L1 SI and L1 CSF SI. Regression analysis was performed to determine correlation of VBQ(L1-4) score with age. Coefficient of variation (CV) was used to determine reproducibility between VBQ(L1-4) scores from serial MRI scans.

RESULTS

One hundred thirty-six patients (mean ± SD age 44.9 ± 12.5 years; 53.7% female) were included in this study. Extrinsic factors affecting the VBQ score included patient age, MRI relaxation time, and specific MRI machine. When controlling for MRI relaxation/echo time, the VBQ(L1-4) score was positively correlated with age and had excellent reproducibility in serial MRI with CV of 0.169. There was excellent agreement (ICC > 0.9) of VBQ scores derived from the two formulas, VBQ(L1) and VBQ(L1-4).

CONCLUSION

Extrinsic factors, including MRI technical factors and age, can impact the VBQ(L1-4) score and must be considered when using this tool to estimate bone mineral density (BMD). VBQ(L1-4) score was positively correlated with age. Reproducibility of the VBQ(L1-4) score across serial MRI is excellent especially when controlling for technical factors, supporting use of the VBQ score in estimating BMD. The VBQ(L1) score was a reliable alternative to the VBQ(L1-4) score.

Update on the clinical use of trabecular bone score (TBS) in the management of osteoporosis: results of an expert group meeting organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), and the International Osteoporosis Foundation (IOF) under the auspices of WHO Collaborating Center for Epidemiology of Musculoskeletal Health and Aging

PURPOSE

Trabecular bone score (TBS) is a grey-level textural measurement acquired from dual-energy X-ray absorptiometry lumbar spine images and is a validated index of bone microarchitecture. In 2015, a Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) published a review of the TBS literature, concluding that TBS predicts hip and major osteoporotic fracture, at least partly independent of bone mineral density (BMD) and clinical risk factors. It was also concluded that TBS is potentially amenable to change as a result of pharmacological therapy. Further evidence on the utility of TBS has since accumulated in both primary and secondary osteoporosis, and the introduction of FRAX and BMD T-score adjustment for TBS has accelerated adoption. This position paper therefore presents a review of the updated scientific literature and provides expert consensus statements and corresponding operational guidelines for the use of TBS.

METHODS

An Expert Working Group was convened by the ESCEO and a systematic review of the evidence undertaken, with defined search strategies for four key topics with respect to the potential use of TBS: (1) fracture prediction in men and women; (2) initiating and monitoring treatment in postmenopausal osteoporosis; (3) fracture prediction in secondary osteoporosis; and (4) treatment monitoring in secondary osteoporosis. Statements to guide the clinical use of TBS were derived from the review and graded by consensus using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

A total of 96 articles were reviewed and included data on the use of TBS for fracture prediction in men and women, from over 20 countries. The updated evidence shows that TBS enhances fracture risk prediction in both primary and secondary osteoporosis, and can, when taken with BMD and clinical risk factors, inform treatment initiation and the choice of antiosteoporosis treatment. Evidence also indicates that TBS provides useful adjunctive information in monitoring treatment with long-term denosumab and anabolic agents. All expert consensus statements were voted as strongly recommended.

CONCLUSION

The addition of TBS assessment to FRAX and/or BMD enhances fracture risk prediction in primary and secondary osteoporosis, adding useful information for treatment decision-making and monitoring. The expert consensus statements provided in this paper can be used to guide the integration of TBS in clinical practice for the assessment and management of osteoporosis. An example of an operational approach is provided in the appendix. This position paper presents an up-to-date review of the evidence base, synthesised through expert consensus statements, which informs the implementation of Trabecular Bone Score in clinical practice.

Abaloparatide Has the Same Catabolic Effects on Bones of Mice When Infused as PTH (1-34)

Abaloparatide is a peptide analog of parathyroid hormone-related protein (PTHrP 1-34) and was approved in 2017 as the second osteoanabolic peptide for treating osteoporosis. We previously showed that intermittent abaloparatide is equally as effective as PTH (1-34). This study was designed to compare the catabolic effects of PTH (1-34) and abaloparatide on bone in young female wild-type mice. Two-month-old C57Bl/6J female mice were continuously infused with human PTH (1-34) or abaloparatide at 80 μg/kg BW/day or vehicle for 2 weeks. At euthanasia, DEXA-PIXImus was performed to assess bone mineral density (BMD) in the whole body, femurs, tibiae, and vertebrae. Bone turnover marker levels were measured in sera, femurs were harvested for micro-computer tomography (μCT) analyses and histomorphometry, and tibiae were separated into cortical and trabecular fractions for gene expression analyses. Our results demonstrated that the infusion of abaloparatide resulted in a similar decrease in BMD as infused PTH (1-34) at all sites. μCT and histomorphometry analyses showed similar decreases in cortical bone thickness and BMD associated with an increase in bone turnover from the increased bone formation rate found by in vivo double labeling and serum P1NP and increased bone resorption as shown by osteoclast numbers and serum cross-linked C-telopeptide. Trabecular bone did not show major changes with either treatment. Osteoblastic gene expression analyses of trabecular and cortical bone revealed that infusion of PTH (1-34) or abaloparatide led to similar and different actions in genes of osteoblast differentiation and activity. As with intermittent and in vitro treatment, both infused PTH (1-34) and abaloparatide similarly regulated downstream genes of the PTHR1/SIK/HDAC4 pathway such as Sost and Mmp13 but differed for those of the PTHR1/SIK/CRTC pathway. Taken together, at the same dose, infused abaloparatide causes the same high bone turnover as infused PTH (1-34) with a net resorption in female wild-type mice. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effect of Abaloparatide on Bone Microarchitecture Assessed by Trabecular Bone Score in Women With Osteoporosis: Post Hoc Analysis of ACTIVE and ACTIVExtend

Although bone mineral density (BMD) is a predictor of fracture, many fractures occur in women with T-scores > -2.5. Bone microarchitecture, assessed by trabecular bone score (TBS), predicts fracture risk independent of BMD. We evaluated whether abaloparatide improves TBS and whether TBS trends were associated with vertebral fracture risk reduction. Women with osteoporosis randomized to abaloparatide or placebo for 18 months (ACTIVE), followed by alendronate for 24 months (ACTIVExtend), with evaluable TBS, were included in this post hoc analysis (N = 911). TBS was calculated from spine BMD scans using an algorithm adjusted for tissue thickness (TBS_th ) at baseline, 6, 18, and 43 months. Mean increments in TBS_th from baseline within and between treatment groups, proportion of women with TBS_th increments above least significant change (LSC) and proportion with degraded TBS_th (<1.027) were calculated. Risk estimates for vertebral fracture were compared using binary logistic regressions adjusted for baseline age and spine BMD. At baseline, 42% had degraded TBS_th . Mean TBS_th increased 4% after 18 months abaloparatide (p < 0.001) and was unchanged with placebo. After 2 subsequent years of alendronate, the total cumulative TBS_th increase was 4.4% with abaloparatide/alendronate and 1.7% with placebo/alendronate (group difference, p < 0.001). At 43 months, the proportion of women with degraded TBS_th had declined to 21% with abaloparatide/alendronate and 37% with placebo/alendronate (p < 0.05). An increase in TBS_th  ≥ LSC was observed in 50% of abaloparatide-treated women at 18 months and was associated with decreased odds (odds ratio [OR]; 95% confidence interval [CI]) of vertebral fracture (0.19; 95% CI, 0.04-0.80, 6 months; 0.30; 95% CI, 0.11-0.79, 43 months). In conclusion, abaloparatide increased TBS_th rapidly and progressively over 18 months and increments were maintained over 2 years with alendronate. TBS_th increase was associated with vertebral fracture risk reduction. Microarchitectural improvement may be one mechanism by which abaloparatide strengthens vertebral bone. © 2023 Radius Health, Inc and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Trabecular bone score in rheumatic disease

Patients with rheumatic diseases (RD) are at high risk of osteoporosis (OP) and osteoporotic fractures. The Trabecular bone score (TBS) is a relatively novel method of assessing bone quality, which independently predicts fracture risk regardless of bone mineral density (BMD). A lower TBS in patients with RD compared to controls is shown in most studies concerning TBS and RD. The data obtained indicate that TBS predicts fractures better in RD, especially in patients receiving glucocorticoids, than BMD or the FRAX algorithm. TBS degradation has been associated with disease activity in ankylosing spondylitis, systemic sclerosis, and rheumatoid arthritis in a few studies. However, there is little data in the literature on the effect of rheumatic disease therapy and OP treatment in patients with RD on predictive ability of TBS for incident fracture.

Advancement in the Treatment of Osteoporosis and the Effects on Bone Healing

Osteoporosis (OP) is a major global health concern, with aging being one of the most important risk factors. Osteoarthritis (OA) is also an age-related disorder. Patients with OP and/or OA may be treated surgically for fractures or when their quality of life is impaired. Poor bone quality due to OP can seriously complicate the stability of a bone fixation construct and/or surgical fracture treatment. This review summarizes the current knowledge on the pathophysiology of normal and osteoporotic bone healing, the effect of a bone fracture on bone turnover markers, the diagnosis of a low bone mineral density (BMD) before surgical intervention, and the effect of available anti-osteoporosis treatment. Interventions that improve bone health may enhance the probability of favorable surgical outcomes. Fracture healing and the treatment of atypical femoral fractures are also discussed.

Update on trabecular bone score

Trabecular bone score (TBS) is an indirect and noninvasive measure of bone quality. A low TBS indicates degraded bone microarchitecture, predicts osteoporotic fracture, and is partially independent of clinical risk factors and bone mineral density (BMD). There is substantial evidence supporting the use of TBS to assess vertebral, hip, and major osteoporotic fracture risk in postmenopausal women, as well as to assess hip and major osteoporotic fracture risk in men aged > 50 years. TBS complements BMD information and can be used to adjust the FRAX (Fracture Risk Assessment) score to improve risk stratification. While TBS should not be used to monitor antiresorptive therapy, it may be potentially useful for monitoring anabolic therapy. There is also a growing body of evidence indicating that TBS is particularly useful as an adjunct to BMD for fracture risk assessment in conditions associated with increased fracture risk, such as type-2 diabetes, chronic corticosteroid excess, and other conditions wherein BMD readings are often misleading. The interference of abdominal soft tissue thickness (STT) on TBS should also be considered when interpreting these findings because image noise can impact TBS evaluation. A new TBS software version based on an algorithm that accounts for STT rather than BMI seems to correct this technical limitation and is under development. In this paper, we review the current state of TBS, its technical aspects, and its evolving role in the assessment and management of several clinical conditions.

ACR Appropriateness Criteria® Osteoporosis and Bone Mineral Density: 2022 Update

Osteoporosis constitutes a significant public health risk. An estimated 10.2 million adults in the United States >50 years of age have osteoporosis, a systemic condition that weakens the bones increasing the susceptibility for fractures. Approximately one-half of women and nearly one-third of men >50 years of age will sustain an osteoporotic fracture. These fractures are associated with a decrease in quality of life, diminished physical function, and reduced independence. Dual-energy X-ray absorptiometry (DXA) is the primary imaging modality used to screen for osteoporosis in women >65 years of age and men >70 years of age. DXA may be used in patients <65 years of age to evaluate bone mass density if there are additional risk factors. In certain situations, vertebral fracture assessment and trabecular bone score may further predict fracture risk, particularly in patients who are not yet osteoporotic but are in the range of osteopenia. Quantitative CT is useful in patients with advanced degenerative changes in the spine. Given the proven efficacy of pharmacologic therapy, the role of imaging to appropriately identify and monitor high-risk individuals is critical in substantially reducing osteoporosis-associated morbidity and mortality, and reducing the considerable cost to the health care system. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Comparative effectiveness and cardiovascular safety of abaloparatide and teriparatide in postmenopausal women new to anabolic therapy: A US administrative claims database study

Real-world evidence on the comparative effectiveness and safety of abaloparatide versus teriparatide in women with osteoporosis may help inform treatment decisions. Following 18 months of treatment, abaloparatide was comparable to teriparatide for prevention of nonvertebral fractures, resulted in a 22% risk reduction for hip fractures, and demonstrated similar cardiovascular safety. Osteoporotic fracture risk can be reduced with anabolic or antiresorptive medications. In addition to efficacy and safety data from controlled clinical trials, real-world evidence on comparative effectiveness and safety may help inform treatment decisions.

INTRODUCTION

The real-world effectiveness of abaloparatide versus teriparatide on nonvertebral fracture (NVF) incidence and cardiovascular safety during the 19-month period after treatment initiation were evaluated (NCT04974723).

METHODS

Anonymized US patient claims data from Symphony Health, Integrated Dataverse (IDV)®, May 1, 2017 to July 31, 2019, included women aged ≥ 50 years with ≥ 1 prescription of abaloparatide or teriparatide and no prior anabolic therapy. Most were enrolled in commercial and Medicare health plans. Index was the date of the initial prescription dispensed during the identification period. In 1:1 propensity score matched cohorts, time to first NVF following index date, major adverse cardiovascular events (MACE), and MACE + heart failure (HF) were compared between cohorts using a Cox proportional hazards model.

RESULTS

Propensity score matching yielded 11,616 patients per cohort. Overall median age (interquartile range) was 67 (61, 75) years, and 25.6% had a fracture history. Over 19 months, 335 patients on abaloparatide and 375 on teriparatide had a NVF (hazard ratio [95% confidence interval]: 0.89 [0.77, 1.03]), and 121 and 154 patients, respectively, had a hip fracture [HR (95% CI): 0.78 (0.62, 1.00)]. The MACE and MACE + HF rates were similar between cohorts.

CONCLUSIONS

Following 18 months of treatment, abaloparatide was comparable to teriparatide for prevention of NVF and similar cardiovascular safety was demonstrated between cohorts.

Denosumab After Teriparatide in Premenopausal Women With Idiopathic Osteoporosis

CONTEXT

We have previously reported that teriparatide is associated with substantial increases in bone mineral density (BMD) at the lumbar spine (LS), total hip (TH), and femoral neck (FN) and small declines at the distal radius in 41 premenopausal women with idiopathic osteoporosis (IOP), all severely affected with low trauma fractures and/or very low BMD. Effects of teriparatide dissipate if not followed by antiresorptives.

OBJECTIVE

To assess the effects of 12 and 24 months of denosumab in premenopausal women with IOP completing 24 months of teriparatide.

METHODS

This was a preplanned phase 2B extension study. Premenopausal women with IOP who had completed a course of teriparatide received denosumab 60 mg every 6 months over 24 months. The main outcome measure was within-group change in BMD at the LS at 12 months. Secondary outcomes include change in 12-month BMD at other sites, 24-month BMD at all sites, trabecular bone score (TBS), and bone turnover markers (BTMs).

RESULTS

After completing teriparatide, 32 participants took denosumab for 12 months and 29 for 24 months, with statistically significant increases in BMD at the LS (5.2 ± 2.6% and 6.9 ± 2.6%), TH (2.9 ± 2.4% and 4.6 ± 2.8%), and FN (3.0 ± 3.8% and 4.7 ± 4.9%). Over the entire 24-month teriparatide and 24-month denosumab treatment period, BMD increased by 21.9 ± 7.8% at the LS, 9.8 ± 4.6% at the TH, and 9.5 ± 4.7% at the FN (all P < .0001). TBS increased by 5.8 ± 5.6% (P < .001). Serum BTM decreased by 75% to 85% by 3 months and remained suppressed through 12 months of denosumab. Denosumab was generally well tolerated.

CONCLUSION

These data support the use of sequential teriparatide and denosumab to increase BMD in premenopausal women with severe osteoporosis.

Effect of Romosozumab on Trabecular Bone Score Compared to Anti-Resorptive Agents in Postmenopausal Women with Osteoporosis

BACKGROUND

Romosozumab has shown significant improvement in bone mineral density (BMD) in previously reported trials. However, BMD reflects only bone strength and does not offer insight into the bone microarchitecture. The trabecular bone score (TBS) is a non-invasive tool used to assess bone microarchitecture. Several previous studies have evaluated the efficacy of anti-osteoporotic agents using the TBS. However, data regarding the potency of romosozumab based on the TBS is lacking. This retrospective observational cohort study demonstrated the impact of romosozumab use on the TBS.

METHODS

The primary outcome was the percentage change in the TBS from baseline to post-treatment. Postmenopausal osteoporosis patients were followed up for 6 and 12 months after romosozumab (210 mg monthly, N =10) and denosumab (60 mg every 6 months, N=21) or ibandronate (150 mg monthly, N=24) treatments, respectively. Patients who had previously used osteoporosis medications were included, if any the washout period was sufficient.

RESULTS

The percentage change in TBS from baseline to post-treatment was 2.53±2.98% (6 months, N=10; P=0.04), 0.59%±3.26% (12 months, N=21; P=0.48), and -0.45±3.66% (12 months, N=24; P=0.51) in the romosozumab, denosumab, and ibandronate groups, respectively. Romosozumab demonstrated a noticeable increase in TBS, although it did not reach the least significant change (5.8%) in TBS.

CONCLUSIONS

Romosozumab improved the TBS in postmenopausal women with osteoporosis. TBS may be potentially useful for monitoring romosozumab treatment.

Effect of testosterone treatment on the trabecular bone score in older men with low serum testosterone

The trabecular bone score (TBS) is an indirect measure of vertebral bone microarchitecture. Our objective was to examine the effect of testosterone treatment on TBS. One hundred and ninety-seven hypogonadal men were randomized to testosterone or placebo. After 12 months, there was no difference in the changes in TBS by randomized group.

INTRODUCTION

In the Bone Trial of the Testosterone Trials, testosterone treatment increased trabecular volumetric bone mineral density (vBMD) and increased estimated bone strength as determined by finite element analysis. The trabecular bone score (TBS) is an indirect measure of vertebral bone microarchitecture. TBS predicts fracture independent of lumbar spine areal (a) BMD. The objective of this study was to examine the effect of testosterone treatment on TBS compared to its effects on vBMD and aBMD.

METHODS

Two hundred and eleven men were enrolled in the Bone Trial of the Testosterone Trials. Of these, 197 men had 2 repeat TBS and vBMD measurements; 105 men were allocated to receive testosterone, and 92 men to placebo for 1 year. TBS, aBMD, and vBMD were assessed at baseline and month 12.

RESULTS

There was no difference in the percent change in TBS by randomized group: 1.6% (95% confidence intervals (CI) 0.2-3.9) in the testosterone group and 1.4% (95% CI -0.2, 3.1) in the placebo group. In contrast, vBMD increased by 6% (95% CI 4.5-7.5) in the testosterone group compared to 0.4% (95% CI -1.65-0.88) in the placebo groups.

CONCLUSIONS

TBS is not clinically useful in monitoring the 1-year effect of testosterone treatment on bone structure in older hypogonadal men.

Lower trabecular bone score is associated with an increased incidence of localized femoral periosteal thickening

INTRODUCTION

Femoral localized periosteal thickening (LPT, also termed "beaking") of the lateral cortex often precedes an atypical femoral fracture (AFF). Bisphosphonate (BP) use, glucocorticoid use, and Asian race are major risk factors for developing such fractures. The aim of this study was to determine whether the trabecular bone score (TBS) reflecting the lumbar trabecular microarchitecture was related to LPT in glucocorticoid-treated Japanese patients with autoimmune diseases.

MATERIALS AND METHODS

We retrospectively investigated 111 women with autoimmune diseases treated with prednisolone (PSL) who had undergone both femoral X-ray and dual-energy X-ray absorptiometry of the L1 - L4 lumbar vertebrae and for whom TBS could be evaluated for two or more of these.

RESULTS

Femoral LPT was evident in the X-rays of 18 of 111 patients (16.2%). Higher body mass index (BMI), longer duration of PSL use and longer duration of BP use were significant in patients with LPT compared to those without. The TBS was significantly lower in patients with LPT than in those without (1.314 ± 0.092 vs. 1.365 ± 0.100, p = 0.044); however, the lumbar bone mineral density did not differ significantly (0.892 ± 0.141 vs. 0.897 ± 0.154 g/cm², p = 0.897). TBS was significantly associated with LPT (odds ratio, 0.004; 95% CI, 0 - 0.96; p = 0.048), but not in the multivariate analysis including BMI, duration of PSL use and duration of BP use.

CONCLUSIONS

The TBS was lower in glucocorticoid-treated Japanese women with autoimmune diseases with LPT than in those without LPT, and deteriorated trabecular microarchitecture influenced by longer use of BP and glucocorticoid might be associated with the development of LPT.

Increased Potential of Bone Formation with the Intravenous Injection of a Parathyroid Hormone-Related Protein Minicircle DNA Vector

Osteoporosis is commonly treated via the long-term usage of anti-osteoporotic agents; however, poor drug compliance and undesirable side effects limit their treatment efficacy. The parathyroid hormone-related protein (PTHrP) is essential for normal bone formation and remodeling; thus, may be used as an anti-osteoporotic agent. Here, we developed a platform for the delivery of a single peptide composed of two regions of the PTHrP protein (1–34 and 107–139); mcPTHrP 1–34+107–139 using a minicircle vector. We also transfected mcPTHrP 1–34+107–139 into human mesenchymal stem cells (MSCs) and generated Thru 1–34+107–139-producing engineered MSCs (eMSCs) as an alternative delivery system. Osteoporosis was induced in 12-week-old C57BL/6 female mice via ovariectomy. The ovariectomized (OVX) mice were then treated with the two systems; (1) mcPTHrP 1–34+107–139 was intravenously administered three times (once per week); (2) eMSCs were intraperitoneally administered twice (on weeks four and six). Compared with the control OVX mice, the mcPTHrP 1–34+107–139-treated group showed better trabecular bone structure quality, increased bone formation, and decreased bone resorption. Similar results were observed in the eMSCs-treated OVX mice. Altogether, these results provide experimental evidence to support the potential of delivering PTHrP 1–34+107–139 using the minicircle technology for the treatment of osteoporosis.

Abaloparatide: A review of preclinical and clinical studies

Osteoporosis is a debilitating disease characterized by reduced bone mineral density and an increased risk of fractures. This review aims to provide a comprehensive overview of, and map current knowledge, obtained from preclinical and clinical studies of the osteoanabolic agent abaloparatide. PubMed and Embase were meticulously searched from inception to May 4, 2021.178 titles and abstracts were screened, and 57 full-text articles were assessed for inclusion. A total of 55 articles were included; 5 (9%) in vitro studies, 21 (38%) in vivo studies, and 29 (53%) clinical studies. Preclinical in vitro studies have demonstrated receptor conformation preferability, structural insights into the receptor-agonist complex, and proliferative effects of abaloparatide on osteoblasts. Preclinical studies have shown abaloparatide to be similarly effective to teriparatide using comparable doses in both ambulating mice and rats challenged by disuse. Other animal studies have reported that abaloparatide effectively mitigates or prevents bone loss from ovariectomy, orchiectomy, and glucocorticoids and improves fracture healing. The pivotal clinical study ACTIVE demonstrated 18 months of treatment with abaloparatide substantially increase bone mineral density and reduce fracture risk in post-menopausal women compared with placebo. The extension study ACTIVExtend highlighted that subsequent treatment with alendronate sustained the bone gained by abaloparatide treatment and the reduced fracture risk for up to two years. Post-hoc sub-group analyses have also supported the efficacy and safety of abaloparatide treatment independent of various baseline risk factors. In conclusion, mounting evidence from preclinical and clinical studies has uniformly reported that abaloparatide increases bone mineral density and reduces fracture risk.

Application of the Trabecular Bone Score in Clinical Practice

The trabecular bone score (TBS) was introduced as an indirect index of trabecular microarchitecture, complementary to bone mineral density (BMD), and is derived using the same dual energy X-ray absorptiometry images. Recently, it has been approved for clinical use in Korea. Therefore, we conducted a comprehensive review to optimize the use of TBS in clinical practice. The TBS is an independent predictor of osteoporotic fractures in postmenopausal women and men aged >50 years. The TBS is potentially useful in monitoring the skeletal effects of anabolic agents but not of antiresorptive agents. In postmenopausal women with type 2 diabetes mellitus, the TBS assesses osteoporotic fracture risk not captured by BMD. However, high body mass index and soft tissue thickness can cause underestimation of the TBS; however, this limitation has been improved in recent versions of the TBS software. However, a high precision error and low reproducibility limit the use of TBS. This review may provide information on the application of the TBS in clinical practice based on reliable evidence.

Effects of age at estrogen replacement therapy initiation on trabecular bone score in Japanese adults with Turner syndrome

The effects of the age at estrogen replacement therapy (ERT) initiation on bone quality in Turner syndrome were evaluated using trabecular bone score. Early puberty ERT positively correlated with increase in bone quality. Early initiation of ERT is necessary for the acquisition of bone quality as well as bone density.

INTRODUCTION

Studies have reported associations between bone mineral density and estrogen replacement therapy (ERT) in Turner syndrome (TS) patients; however, few studies exist on the effect on bone quality. The aim of this study was to evaluate the effects of the age at ERT initiation on bone quality of Japanese TS patients, cross-sectionally and longitudinally.

METHODS

Cross-sectionally, 95 TS patients were divided into three groups based on their age at initiation of ERT: A (12-14 years, 11 patients), B (15-17 years, 47 patients), and C (over 18 years, 37 patients). To assess bone quality, trabecular bone score (TBS) was used. The effects of age at initiation and duration of ERT on TBS were examined using multiple regression analysis. In the longitudinal study, 48 patients who underwent dual-energy X-ray absorptiometry multiple times were divided into three groups: D (12-14 years, 8 patients), E (15-17 years, 18 patients), and F (over 18 years, 22 patients). Each group was analyzed for the rate of change in TBS per year.

RESULTS

Cross-sectionally, the TBS showed significant differences among the three groups (TBS A, 1.302; B, 1.299; C, 1.245) (p = 0.013); group C was significantly lower than B (p = 0.014); bone quality was degraded. Multiple regression analysis revealed that age at ERT initiation significantly affected the increase in TBS (p = 0.002). Longitudinally, the rate of change of TBS was not significantly different in the three groups (p = 0.73).

CONCLUSION

Early initiation of ERT may have positive effects on bone quality in TS. Large prospective studies will be needed.

Anabolic Agents for Postmenopausal Osteoporosis: How Do You Choose?

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Abaloparatide: an anabolic treatment to reduce fracture risk in postmenopausal women with osteoporosis

OBJECTIVE

Fractures due to osteoporosis represent a serious burden on patients and healthcare systems. The objective of this review is to provide an overview of the anabolic agent abaloparatide (ABL) for the treatment of postmenopausal women with osteoporosis at high risk for fracture.

METHODS

A literature review was conducted using PubMed to identify articles focused on ABL published prior to February 10, 2020, using the search term "abaloparatide".

RESULTS

ABL, a synthetic analog of human parathyroid hormone-related protein, increased bone mineral density (BMD), improved bone microarchitecture, and increased bone strength in preclinical and clinical studies. The pivotal phase 3 trial ACTIVE and its extension (ACTIVExtend) demonstrated the efficacy of initial treatment with ABL for 18 months followed by sequential treatment with alendronate (ALN) for an additional 24 months to reduce the risk of vertebral, nonvertebral, clinical, and major osteoporotic fractures and to increase BMD in postmenopausal women with osteoporosis. Discontinuations from ACTIVE were slightly more common in ABL-treated patients due to dizziness, palpitations, nausea, and headache. Post hoc analyses of ACTIVE and ACTIVExtend support the efficacy and safety of ABL in relevant subpopulations including postmenopausal women with various baseline risk factors, women ≥80 years, women with type 2 diabetes mellitus, and women with renal impairment.

CONCLUSIONS

ABL is an effective and well-tolerated treatment for women with postmenopausal osteoporosis at high risk for fracture. Its therapeutic effects are sustained with subsequent ALN therapy.

Effect of Teriparatide on Bone Remodeling and Density in Premenopausal Idiopathic Osteoporosis: A Phase II Trial

CONTEXT

Premenopausal women with idiopathic osteoporosis (IOP) have abnormal skeletal microarchitecture and variable tissue-level bone formation rate (BFR).

OBJECTIVES

Compare 6 months (M) of teriparatide versus placebo on areal bone mineral density (aBMD) by dual-energy x-ray absorptiometry (DXA), bone turnover markers (BTMs) and BFR at 3M by quadruple-labeled transiliac biopsy. Characterize 12M and 24M effects of teriparatide on aBMD and whether BTMs and BFR predict response.

DESIGN

6M phase 2 randomized controlled trial (RCT) followed by open extension.

SETTING

Tertiary referral centers.

PATIENTS

Premenopausal women with IOP.

INTERVENTIONS

A total of 41 women were randomized to either teriparatide 20 mcg (n = 28) or placebo (n = 13). After 6M, those on placebo switched to teriparatide for 24M; those on teriparatide continued for 18M.

MAIN OUTCOME MEASURES

6M RCT: Between-group differences in lumbar spine (LS) aBMD (percent change from baseline), 3M BFR, and hypercalcemia. Open-label extension: Within-group change in LS aBMD over 12M and 24M. Secondary outcomes included aBMD change at other sites and relationship between BTMs, BFR, and changes in aBMD.

FINDINGS

Over 6M, LS aBMD increased by 5.5% (95% CI: 3.83, 7.19) in teriparatide and 1.5% (95% CI: -0.73, 3.83) in placebo (P = 0.007). There were increases in 3M BTMs, and BFR (cancellous and endocortical BFR: between-groups P = 0.004). Over 24M, teriparatide increased LS aBMD by 13.2% (95% CI: 10.3, 16.2), total hip by 5.2% (95% CI: 3.7, 6.7) and femoral neck by 5.0% (95% CI: 3.2, 6.7; all P ≤ 0.001). Serum N-terminal propeptides of procollagen type 1 (P1NP) and 3M endocortical BFR were moderately associated with LS aBMD response. Teriparatide was well-tolerated.

CONCLUSIONS

Teriparatide increased BFR and formation markers and was associated with marked aBMD improvements in most premenopausal women (82%) with IOP.

Relationship between Skeletal Muscle Mass, Bone Mineral Density, and Trabecular Bone Score in Osteoporotic Vertebral Compression Fractures

STUDY DESIGN

A retrospective observational study was performed.

PURPOSE

We investigated the relationships between skeletal muscle mass, bone mineral density (BMD), and trabecular bone score (TBS) in patients with osteoporotic vertebral compression fractures (VCFs).

OVERVIEW OF LITERATURE

The TBS has attracted attention as a measurement of trabecular bone microarchitecture. It is derived from data obtained using dual-energy X-ray absorptiometry (DXA) and is a reported indicator of VCFs, and its addition to the Fracture Risk Assessment Tool increases the accuracy of fracture prediction.

METHODS

BMD, skeletal muscle mass, and TBS were measured in 142 patients who visited Shimoshizu National Hospital from April to August 2019. Patients were divided into a VCF group and a non-VCF group. Whole-body DXA scans were performed to analyze body composition, including appendicular skeletal muscle mass index (SMI; lean mass [kg]/height [m2]) and BMD. The diagnostic criteria for sarcopenia was an appendicular SMI <5.46 kg/m2. A logistic regression analysis was conducted to identify the risk factors for VCFs.

RESULTS

The significant (p<0.05) findings (VCF group vs. non-VCF group, respectively) included age (79 vs. 70 years), femoral BMD (0.50 vs. 0.58 g/cm2), TBS (1.25 vs. 1.29), and lower limb muscle mass (8.6 vs. 9.9 kg). The VCF group was significantly older and had a lower femur BMD and decreased leg muscle mass than the non-VCF group. Based on the multiple logistic regression analysis, lower femoral BMD and decreased leg muscle mass were identified as risk factors for vertebral fracture independent of age, but the TBS was not.

CONCLUSIONS

Patients with VCFs had low BMD, a low TBS, and low skeletal muscle mass. Lower femoral BMD and decreased leg muscle mass were identified as risk factors for VCFs independent of age, whereas the TBS was not identified as a risk factor for VCFs.

Abaloparatide and the Spine: A Narrative Review

Osteoporosis is a common and debilitating condition characterized by diminished bone mass and architecture leading to bone fragility. Antiresorptive medicines like bisphosphonates (and less commonly denosumab) are the typical first-line agents for the medical treatment of osteoporosis. However, newer anabolic agents have been shown to improve bone mass and architecture, as well as reduce fracture risk, to a greater degree than traditional antiresorptive therapies. Teriparatide (human recombinant parathyroid hormone (PTH) 1–34, Forteo, Ely Lilly, Indianapolis, IN), which was the first in class to be approved in the United States, is the most widely used anabolic osteoporosis medicine and has shown significant benefit over traditional antiresorptive therapies. However, abaloparatide (synthetic parathyroid-related peptide (PTHrP), Tymlos, Radius Health, Waltham, MA), the second drug in this family, has recently become available for use. In this narrative review, we review the mechanism, effects, and benefits of abaloparatide compared to alternative treatments as well as discuss the current literature in regard to its effect on osteoporosis-related complications in the spine.

Anabolic Therapy and Optimal Treatment Sequences for Patients With Osteoporosis at High Risk for Fracture

OBJECTIVE

Provide an update regarding anabolic medications for osteoporosis, which are often considered to be the last resort for patients with osteoporosis, after multiple fractures have already occurred and other medications have already been administered.

METHODS

Literature review and discussion.

RESULTS

Recent pivotal trial data for anabolic agents and randomized trials comparing anabolic and antiresorptive medications suggest that three anabolic agents (teriparatide, abaloparatide, and romosozumab) reduce nonvertebral and vertebral fractures faster and to a greater extent than potent antiresorptive treatments. Furthermore, bone density accrual is maximized when patients are given anabolic agents first, followed by potent antiresorptive therapy. Since total hip bone density during or after osteoporosis treatment has emerged as an excellent surrogate for future fracture risk, attaining a greater hip bone mineral density is a treatment goal for high-risk osteoporosis patients.

CONCLUSION

This review defines the highest-risk patients and summarizes the rationale for the evolving role of anabolic therapy in the management of postmenopausal women at high risk for fracture.

ABBREVIATIONS

ACTIVE = Abaloparatide Comparator Trial in Vertebral Endpoints; ARCH = Active Controlled Fracture Study in Postmenopausal Women with Osteoporosis at High Risk; BMD = bone mineral density; FRAME = Fracture Study in Postmenopausal Women with Osteoporosis; FRAX = Fracture Risk Assessment Tool; PTH = parathyroid hormone; TBS = trabecular bone score.

Bone Health Optimization in Orthopaedic Surgery

BACKGROUND

Osteoporosis is associated with adverse orthopaedic surgical outcomes. Bone health optimization is a preoperative intervention intended to reduce the likelihood of postoperative complications. We aimed to characterize a patient cohort referred for bone health optimization to test the hypothesis that poor bone quality is common in orthopaedic surgery and that many such patients meet guidelines for osteoporosis treatment.

METHODS

This retrospective study evaluated 124 patients referred for bone health optimization who were ≥50 years of age and candidates for arthroplasty or thoracolumbar surgery. The Fracture Risk Assessment Tool (FRAX) risk factors and dual x-ray absorptiometry (DXA) results were collected. When available, opportunistic computed tomographic (CT) imaging and the trabecular bone score were evaluated. The World Health Organization (WHO) diagnostic and National Osteoporosis Foundation (NOF) treatment guidelines were applied.

RESULTS

All patients were referred by their orthopaedic surgeon; their mean age was 69.2 years, 83% of patients were female, 97% were Caucasian, and 56% had sustained a previous fracture. The mean historical height loss (and standard deviation) was 5.3 ± 3.3 cm for women and 6.0 ± 3.6 cm for men. The mean lowest T-score of the hip, spine, or wrist was -2.43 ± 0.90 points in women and -2.04 ± 0.81 points in men (p < 0.08). Osteoporosis (T-score of ≤-2.5 points) was present in 45% of women and 20% of men; only 3% of women and 10% of men had normal bone mineral density. Opportunistic CT scans identified 60% of patients as likely having osteoporosis. The trabecular bone score identified 34% of patients with degraded bone microarchitecture and 30% of patients with partially degraded bone microarchitecture. The NOF threshold for osteoporosis treatment was met in 91% of patients. Treatment was prescribed in 75% of patients (45% anabolic therapy and 30% antiresorptive therapy).

CONCLUSIONS

Osteoporosis, degraded bone microarchitecture, prior fracture, and elevated fracture risk were common. Given the high prevalence of impaired bone health in this cohort, we believe that bone health screening, including FRAX assessment, should be considered in selected patients undergoing orthopaedic surgery as part of the preoperative optimization for all adults who are ≥50 years of age.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Artificial neural network analysis of bone quality DXA parameters response to teriparatide in fractured osteoporotic patients

Teriparatide is a bone-forming therapy for osteoporosis that increases bone quantity and texture, with uncertain action on bone geometry. No data are available regarding its influence on bone strain. To investigate teriparatide action on parameters of bone quantity and quality and on Bone Strain Index (BSI), also derived from DXA lumbar scan, based on the mathematical model finite element method. Forty osteoporotic patients with fractures were studied before and after two years of daily subcutaneous 20 mcg of teriparatide with dual X-ray photon absorptiometry to assess bone mineral density (BMD), hip structural analysis (HSA), trabecular bone score (TBS), BSI. Spine deformity index (SDI) was calculated from spine X-ray. Shapiro-Wilks, Wilcoxon and Student's t test were used for classical statistical analysis. Auto Contractive Map was used for Artificial Neural Network Analysis (ANNs). In the entire population, the ameliorations after therapy regarded BSI (-13.9%), TBS (5.08%), BMD (8.36%). HSA parameters of femoral shaft showed a worsening. Dividing patients into responders (BMD increase >10%) and non-responders, the first presented TBS and BSI ameliorations (11.87% and -25.46%, respectively). Non-responders presented an amelioration of BSI only, but less than in the other subgroup (-6.57%). ANNs maps reflect the mentioned bone quality improvements. Teriparatide appears to ameliorate not only BMD and TBS, but also BSI, suggesting an increase of bone strength that may explain the known reduction in fracture risk, not simply justified by BMD increase. BSI appears to be a sensitive index of TPD effect. ANNs appears to be a valid tool to investigate complex clinical systems.

Abaloparatide in Postmenopausal Women With Osteoporosis and Type 2 Diabetes: A Post Hoc Analysis of the ACTIVE Study

Type 2 diabetes mellitus (T2DM) increases fracture risk despite normal or increased BMD. Abaloparatide reduces fracture risk in patients with postmenopausal osteoporosis (PMO); however, its efficacy in women with T2DM is unknown. This post hoc analysis evaluated the efficacy and safety of abaloparatide in patients with T2DM. The analysis included patients with T2DM from the Abaloparatide Comparator Trial In Vertebral Endpoints (ACTIVE), a phase 3, double‐blind, randomized, placebo‐ and active‐controlled trial. In ACTIVE, participants were randomized 1:1:1 to daily s.c. injections of placebo, abaloparatide (80 μg), or open‐label teriparatide (20 μg) for 18 months. A total of 198 women with PMO and T2DM from 21 centers in 10 countries were identified from ACTIVE through review of their medical records. The main outcomes measured included effect of abaloparatide versus placebo on BMD and trabecular bone score (TBS), with secondary outcomes of fracture risk and safety, in patients from ACTIVE with T2DM. Significant (p < 0.001) improvements in BMD at total hip (mean change 3.0% versus −0.4%), femoral neck (2.6% versus −0.2%), and lumbar spine (8.9% versus 1.3%) and TBS at lumbar spine (3.72% versus −0.56%) were observed with abaloparatide versus placebo at 18 months. Fracture events were fewer with abaloparatide treatment in patients with T2DM, and differences were not significant between groups except nonvertebral fractures in the abaloparatide versus placebo groups (p = 0.04). Safety was consistent with the ACTIVE population. In conclusion, in women with PMO and T2DM, abaloparatide treatment resulted in significant improvements in BMD and TBS versus placebo, consistent with the overall ACTIVE population © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Effects of Intermittent Administration of Parathyroid Hormone and Parathyroid Hormone-Related Protein on Fracture Healing: A Narrative Review of Animal and Human Studies

Intermittent administration of parathyroid hormone (PTH) stimulates skeletal remodeling and is a potent anabolic agent in bone. PTH‐related protein (PTHrP) is anabolic acting on the same PTH1 receptor and is in therapeutic use for osteoporosis. The body of literature for PTH actions in fracture healing is emerging with promising yet not entirely consistent results. The objective of this review was to perform a literature analysis to extract up‐to‐date knowledge on the effects of intermittent PTH and PTHrP therapy in bone fracture healing. A literature search of the PubMed database was performed. Clinical case studies and articles related to “regeneration,” “implant,” and “distraction osteogenesis” were excluded. A narrative review was performed to deliberate the therapeutic potential of intermittent PTH administration on fracture healing. A smaller number of studies centered on the use of PTHrP or a PTHrP analog were also reviewed. Animal studies clearly show that intermittent PTH therapy promotes fracture healing and revealed the strong therapeutic potential of PTH. Human subject studies were fewer and not as consistent as the animal studies yet provide insight into the potential of intermittent PTH administration on fracture healing. Differences in outcomes for animal and human studies appear to be attributed partly to variable doses, fracture sites, age, remodeling patterns, and bone architectures, although other factors are involved. Future studies to examine the dose, timing, and duration of PTH administration will be necessary to further delineate the therapeutic potential of PTH for fracture healing in humans. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Dual-energy X-ray Absorptiometry Monitoring with Trabecular Bone Score: 2019 ISCD Official Position

Trabecular bone score (TBS) is a textural index that evaluates pixel gray-level variations in the lumbar spine image by dual-energy X-ray absorptiometry. It provides an indirect assessment of trabecular microarchitecture that is an independent predictor of fracture risk. TBS does not appear to be clinically useful to monitor the skeletal effects of bisphosphonates and denosumab, but is potentially useful as a component of monitoring the skeletal effects of teriparatide and abaloparatide. The least significant change (LSC) for TBS can be conservatively estimated to be about 5.8% (the largest LSC in published data) or calculated by a dual-energy X-ray absorptiometry facility using the same methodology that is used for bone mineral density (BMD) precision assessment to calculate BMD LSC. A review of the best available evidence at the 2019 ISCD Position Development Conference concluded that the role of TBS in monitoring antiresorptive therapy is unclear and that TBS is potentially useful for monitoring anabolic therapy. For patients treated with teriparatide or abaloparatide, a statistically significant increase in TBS may represent a clinically meaningful improvement in trabecular structure. A significant decrease of TBS may represent a worsening of trabecular structure, suggesting the need for further clinical assessment and possible change in treatment strategies. Since BMD measures bone quantity and TBS measures bone quality, these tests can be considered complementary in assessing fracture risk and response to therapy in appropriate patients.

Abaloparatide exhibits greater osteoanabolic response and higher cAMP stimulation and β-arrestin recruitment than teriparatide

Teriparatide and abaloparatide are parathyroid hormone receptor 1 (PTHR1) analogs with unexplained differential efficacy for the treatment of osteoporosis. Therefore, we compared the effects of abaloparatide and teriparatide on bone structure, turnover, and levels of receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG). Wild-type (WT) female mice were injected daily with vehicle or 20-80 µg/kg/day of teriparatide or abaloparatide for 30 days. Femurs and spines were examined by microcomputed tomography scanning and serum levels of bone turnover markers, RANKL, and OPG, were measured by ELISA. Both analogs similarly increased the distal femoral fractional trabecular bone volume, connectivity, and number, and reduced the structure model index (SMI) at 20-80 µg/kg/day doses. However, only abaloparatide exhibited a significant increase (13%) in trabecular thickness at 20 µg/kg/day dose. Femoral cortical evaluation showed that abaloparatide caused a greater dose-dependent increase in cortical thickness than teriparatide. Both teriparatide and abaloparatide increased lumbar 5 vertebral trabecular connectivity but had no or modest effect on other indices. Biochemical analysis demonstrated that abaloparatide promoted greater elevation of procollagen type 1 intact N-terminal propeptide, a bone formation marker, and tartrate-resistant acid phosphatase 5b levels, a bone resorption marker, and lowered the RANKL/OPG ratio. Furthermore, PTHR1 signaling was compared in cells treated with 0-100 nmol/L analog. Interestingly, abaloparatide had a markedly lower EC50 for cAMP formation (2.3-fold) and β-arrestin recruitment (1.6-fold) than teriparatide. Therefore, abaloparatide-improved efficacy can be attributed to enhanced bone formation and cortical structure, reduced RANKL/OPG ratio, and amplified Gs-cAMP and β-arrestin signaling.

The Response of Osteoblasts and Bone to Sinusoidal Electromagnetic Fields: Insights from the Literature

Electromagnetic fields (EMFs) have been proposed as a tool to ameliorate bone formation and healing. Despite their promising results, however, they have failed to enter routine clinical protocols to treat bone conditions where higher bone mass has to be achieved. This is no doubt also due to a fundamental lack of knowledge and understanding on their effects and the optimal settings for attaining the desired therapeutic effects. This review analysed the available in vitro and in vivo studies that assessed the effects of sinusoidal EMFs (SEMFs) on bone and bone cells, comparing the results and investigating possible mechanisms of action by which SEMFs interact with tissues and cells. The effects of SEMFs on bone have not been as thoroughly investigated as pulsed EMFs; however, abundant evidence shows that SEMFs affect the proliferation and differentiation of osteoblastic cells, acting on multiple cellular mechanisms. SEMFs have also proven to increase bone mass in rodents under normal conditions and in osteoporotic animals.

Abaloparatide effect on forearm bone mineral density and wrist fracture risk in postmenopausal women with osteoporosis

PURPOSE

Wrist fractures are common, contribute significantly to morbidity in women with postmenopausal osteoporosis, and occur predominantly at the ultradistal radius, a site rich in trabecular bone. This exploratory analysis of the phase 3 ACTIVE study evaluated effects of abaloparatide versus placebo and teriparatide on forearm bone mineral density (BMD) and risk of wrist fracture.

METHODS

Forearm BMD was measured by dual energy X-ray absorptiometry in a subset of 982 women from ACTIVE, evenly distributed across the three treatment groups. Wrist fractures were ascertained in the total cohort (N = 2463).

RESULTS

After 18 months, ultradistal radius BMD changes from baseline were 2.25 percentage points greater for abaloparatide compared with placebo (95% confidence interval (CI) 1.38, 3.12, p < 0.001) and 1.54 percentage points greater for abaloparatide compared with teriparatide (95% CI 0.64, 2.45, p < 0.001). At 18 months, 1/3 radius BMD losses (versus baseline) were similar for abaloparatide compared with placebo (-0.42; 95% CI -1.03, 0.20; p = 0.19) but losses with teriparatide exceeded those of placebo (-1.66%; 95% CI -2.27, -1.06; p < 0.001). The decline with abaloparatide was less than that seen with teriparatide (group difference 1.22%; 95% CI 0.57, 1.87; p < 0.001). The radius BMD findings, at both ultradistal and 1/3 sites, are consistent with the numerically lower incidence of wrist fractures observed in women treated with abaloparatide compared with teriparatide (HR = 0.43; 95% CI 0.18, 1.03; p = 0.052) and placebo (HR = 0.49, 95% CI 0.20, 1.19, p = 0.11).

CONCLUSIONS

Compared with teriparatide, abaloparatide increased BMD at the ultradistal radius (primarily trabecular bone) and decreased BMD to a lesser extent at the 1/3 radius (primarily cortical bone), likely contributing to the numerically lower wrist fracture incidence observed with abaloparatide.

New therapeutic targets for osteoporosis

New anti-osteoporotic agents have been developed, potentially enriching the therapeutic armamentarium. Currently available osteoanabolic therapies are the parathyroid hormone (PTH) and PTH-related peptide (PTHrP) synthetic analogues, teriparatide and abaloparatide. Daily administration at doses of 20 and 80 μg, respectively, in contrast to continuous PTH secretion, leads to increased bone formation and reduces vertebral and non-vertebral fracture risk. Teriparatide is more effective than bisphosphonates (alendronate, risedronate) in increasing bone mineral density (BMD), improving bone architecture and reducing fracture risk. Abaloparatide leads to greater BMD gain, has greater anti-fracture efficacy regarding major osteoporotic fractures (upper arm, wrist, hip or clinical spine) compared with teriparatide (without a difference in morphometric vertebral and non-vertebral fractures), and has a lower risk of hypercalcaemia. Romosozumab, a sclerostin inhibitor, both induces bone formation and suppresses bone resorption. Administered at monthly subcutaneous doses of 210 mg, it reduces vertebral, non-vertebral and hip fracture risk compared with either placebo or alendronate. However, concerns have arisen about increased cardiovascular risk, which has suspended its approval by the FDA. Anabolic therapy should always be followed by administration of an anti-resorptive agent, such as bisphosphonates or denosumab, which preserves and may further increase BMD gain. Denosumab provides the greatest benefit for BMD when administered sequentially after its combination with teriparatide for 24 months and constitutes a reasonable option for patients at high risk of fracture. However, longitudinal data are needed to confirm the efficacy and safety of these therapeutic interventions.

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.