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

Effect of bisphosphonate and denosumab treatment on TBS in Japanese breast cancer patients with AIBL

INTRODUCTION

Bisphosphonates and denosumab increase bone mineral density (BMD) for osteoporosis treatment in patients with aromatase inhibitor-associated bone loss (AIBL). This study aimed to directly compare bisphosphonates with denosumab in treating patients with AIBL and to determine the effect of denosumab on the trabecular bone score (TBS).

MATERIALS AND METHODS

Thirty-nine patients with AIBL receiving osteoporosis treatment (21 in the bisphosphonates group and 18 in the denosumab group) were retrospectively evaluated for changes in lumbar spine and femoral BMD, lumbar spine bone quality (assessed by TBS), and blood bone metabolic markers. The Mann-Whitney and Wilcoxon tests were used for statistical evaluation.

RESULTS

After 24 months of treatment, the lumbar spine BMD change rate was 5.82 ± 1.10% with bisphosphonates and 10.49 ± 1.20% with denosumab, with the change rate of denosumab significantly increasing over that of bisphosphonates. The change rate in femoral BMD was 2.69 ± 1.16% with bisphosphonates and 2.95 ± 1.26% with denosumab, with no significant difference between the two groups. The rate of decrease in tartrate-resistant acid phosphatase isoform 5b was significantly higher in the denosumab group. The change rate in TBS at 24 months of treatment was 0.53 ± 1.26% in the bisphosphonates group and 1.08 ± 1.33% in the denosumab group, with no significant difference between the two groups. After 24 months, TBS remained stable.

CONCLUSION

Both bisphosphonates and denosumab may increase BMD, improve bone metabolism, and inhibit bone quality loss in patients with AIBL.

Denosumab improves trabecular bone score in relationship with decrease in fracture risk of women exposed to aromatase inhibitors

PURPOSE

Trabecular bone score (TBS) is a gray-level textural metric that has shown to correlate with risk of fractures in several forms of osteoporosis. The value of TBS in predicting fractures and the effects of bone-active drugs on TBS in aromatase inhibitors (AIs)-induced osteoporosis are still largely unknown. The primary objective of this retrospective study was to assess the effects of denosumab and bisphosphonates (BPs) on TBS and vertebral fractures (VFs) in women exposed to AIs.

METHODS

241 consecutive women (median age 58 years) with early breast cancer undergoing treatment with AIs were evaluated for TBS, bone mineral density (BMD) and morphometric VFs at baseline and after 18-24 months of follow-up. During the study period, 139 women (57.7%) received denosumab 60 mg every 6 months, 53 (22.0%) BPs, whereas 49 women (20.3%) were not treated with bone-active drugs.

RESULTS

Denosumab significantly increased TBS values (from 1.270 to 1.323; P < 0.001) accompanied by a significant decrease in risk of VFs (odds ratio 0.282; P = 0.021). During treatment with BPs, TBS did not significantly change (P = 0.849) and incidence of VFs was not significantly different from women untreated with bone-active drugs (P = 0.427). In the whole population, women with incident VFs showed higher decrease in TBS vs. non-fractured women (P = 0.003), without significant differences in changes of BMD at any skeletal site.

CONCLUSIONS

TBS variation predicts fracture risk in AIs treated women. Denosumab is effective to induce early increase of TBS and reduction in risk of VFs.

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.

High-resolution peripheral quantitative computed tomography: research or clinical practice?

High-resolution peripheral quantitative CT (HR-pQCT) is a low-dose three-dimensional imaging technique, originally developed for in vivo assessment of bone microarchitecture at the distal radius and tibia in osteoporosis. HR-pQCT has the ability to discriminate trabecular and cortical bone compartments, providing densitometric and structural parameters. At present, HR-pQCT is mostly used in research settings, despite evidence showing that it may be a valuable tool in osteoporosis and other diseases. This review summarizes the main applications of HR-pQCT and addresses the limitations that currently prevent its integration into routine clinical practice. In particular, the focus is on the use of HR-pQCT in primary and secondary osteoporosis, chronic kidney disease (CKD), endocrine disorders affecting bone, and rare diseases. A section on novel potential applications of HR-pQCT is also present, including assessment of rheumatic diseases, knee osteoarthritis, distal radius/scaphoid fractures, vascular calcifications, effect of medications, and skeletal muscle. The reviewed literature seems to suggest that a more widespread implementation of HR-pQCT in clinical practice would offer notable opportunities. For instance, HR-pQCT can improve the prediction of incident fractures beyond areal bone mineral density provided by dual-energy X-ray absorptiometry. In addition, HR-pQCT may be used for the monitoring of anti-osteoporotic therapy or for the assessment of mineral and bone disorder associated with CKD. Nevertheless, several obstacles currently prevent a broader use of HR-pQCT and would need to be targeted, such as the small number of installed machines worldwide, the uncertain cost-effectiveness, the need for improved reproducibility, and the limited availability of reference normative data sets.

Long-term effect of denosumab on bone microarchitecture as assessed by tissue thickness-adjusted trabecular bone score in postmenopausal women with osteoporosis: results from FREEDOM and its open-label extension

In postmenopausal women with osteoporosis, up to 10 years of denosumab treatment significantly and continuously improved bone microarchitecture assessed by tissue thickness-adjusted trabecular bone score, independently of bone mineral density. Long-term denosumab treatment decreased the number of high fracture-risk patients and shifted more patients to lower fracture-risk categories.

PURPOSE

To investigate the long-term effect of denosumab on bone microarchitecture assessed by tissue thickness-adjusted trabecular bone score (TBS_TT) in post-hoc subgroup analysis of FREEDOM and open-label extension (OLE).

METHODS

Postmenopausal women with lumbar spine (LS) or total hip BMD T-score <-2.5 and ≥-4.0 who completed the FREEDOM DXA substudy and continued in OLE were included. Patients received either denosumab 60 mg subcutaneously every 6 months for 3 years and same-dose open-label denosumab for 7 years (long-term denosumab; n=150) or placebo for 3 years and open-label denosumab for 7 years (crossover denosumab; n=129). BMD and TBS_TT were assessed on LS DXA scans at FREEDOM baseline, month 1, and years 1-6, 8, and 10.

RESULTS

In long-term denosumab group, continued increases from baseline to years 4, 5, 6, 8, and 10 in BMD (11.6%, 13.7%, 15.5%, 18.5%, and 22.4%) and TBS_TT (3.2%, 2.9%, 4.1%, 3.6%, and 4.7%) were observed (all P < 0.0001). Long-term denosumab treatment decreased the proportion of patients at high fracture-risk (according to TBS_TT and BMD T-score) from baseline up to year 10 (93.7 to 40.4%), resulting in increases in the proportions at medium-risk (6.3 to 53.9%) and low-risk (0 to 5.7%) (P < 0.0001). Similar responses were observed in crossover denosumab group. Changes in BMD and TBS_TT were poorly correlated during denosumab treatment.

CONCLUSION

In postmenopausal women with osteoporosis, up to 10 years of denosumab significantly and continuously improved bone microarchitecture assessed by TBS_TT, independently of BMD, and shifted more patients to lower fracture-risk categories.

Updated trabecular bone score accounting for the soft tissue thickness (TBSTT) demonstrated significantly improved bone microstructure with denosumab in the FREEDOM TBS post hoc analysis

TBS algorithm has been updated to account for regional soft tissue noise. In postmenopausal women with osteoporosis, denosumab improved tissue thickness-adjusted TBS vs placebo independently of bone mineral density over 3 years, with the magnitude of changes from baseline or placebo numerically greater than body mass index-adjusted TBS.

INTRODUCTION

To evaluate the effect of denosumab on bone microarchitecture assessed by trabecular bone score (TBS) in the FREEDOM study using the updated algorithm that accounts for regional soft tissue thickness (TBSTT) in dual-energy X-ray absorptiometry (DXA) images and to compare percent changes from baseline and placebo with classical body mass index (BMI)-adjusted TBS (TBSBMI).

METHODS

Postmenopausal women with lumbar spine or total hip bone mineral density (BMD) T score <  - 2.5 and ≥  - 4.0 received placebo or denosumab 60 mg subcutaneously every 6 months. TBSBMI and TBSTT were assessed on lumbar spine DXA scans at baseline and months 1, 12, 24, and 36 in a subset of 279 women (129 placebo, 150 denosumab) who completed the 3-year FREEDOM DXA substudy and rolled over to open-label extension study.

RESULTS

Baseline characteristics were similar between groups. TBSTT in the denosumab group showed numerically greater changes from both baseline and placebo than TBSBMI at months 12, 24, and 36. Denosumab led to progressive increases in BMD (1.2, 5.6, 8.1, and 10.5%) and TBSTT (0.4, 2.3, 2.6, and 3.3%) from baseline to months 1, 12, 24, and 36, respectively. Both TBS changes were significant vs baseline and placebo from months 12 to 36 (p < 0.0001). As expected, BMD and TBSTT were poorly correlated both at baseline and for changes during treatment.

CONCLUSION

In postmenopausal women with osteoporosis, denosumab significantly improved bone microstructure assessed by TBSTT over 3 years. TBSTT seemed more responsive to denosumab treatment than TBSBMI and was independent of BMD.

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.