New and emerging treatments for osteoporosis

Efficacy and Safety of Denosumab in Osteoporosis or Low Bone Mineral Density Postmenopausal Women

Denosumab, a human monoclonal antibody, acts against the receptor activator of nuclear factor-κB ligand and is a promising antiresorptive agent in patients with osteoporosis. This study aimed to update the efficacy and safety of denosumab vs. placebo in osteoporosis or low bone mineral density (BMD) postmenopausal women. PubMed, Embase, Cochrane library, and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) reporting the efficacy and safety data of denosumab vs. placebo in osteoporosis or low BMD postmenopausal women. A random-effects model was used to calculate pooled weight mean differences (WMDs) or relative risks (RRs) with corresponding 95% confidence intervals (CIs) for treatment effectiveness of denosumab vs. placebo. Eleven RCTs including 12,013 postmenopausal women with osteoporosis or low BMD were preferred for the final meta-analysis. The summary results indicated that the percentage change of BMD in the denosumab group was greater than that of BMD in placebo at 1/3 radius (WMD: 3.43; 95%CI: 3.24–3.62; p < 0.001), femoral neck (WMD: 3.05; 95%CI: 1.78–4.33; p < 0.001), lumbar spine (WMD: 6.25; 95%CI: 4.59–7.92; p < 0.001), total hip (WMD: 4.36; 95%CI: 4.07–4.66; p < 0.001), trochanter (WMD: 6.00; 95%CI: 5.95–6.05; p < 0.001), and total body (WMD: 3.20; 95%CI: 2.03–4.38; p < 0.001). Moreover, denosumab therapy significantly reduced the risk of clinical fractures (RR: 0.57; 95%CI: 0.51–0.63; p < 0.001), nonvertebral fracture (RR: 0.83; 95%CI: 0.70–0.97; p = 0.018), vertebral fracture (RR: 0.32; 95%CI: 0.25–0.40; p < 0.001), and hip fracture (RR: 0.61; 95%CI: 0.37–0.98; p = 0.042). Finally, denosumab did not cause excess risks of adverse events. These findings suggested that postmenopausal women receiving denosumab had increased BMDs and reduced fractures at various sites without inducing any adverse events.

Discovery of potential sclerostin inhibitors from plants with loop2 region of sclerostin inhibition by interacting with residues outside Pro-Asn-Ala-Ile-Gly motif

Sclerostin, an antagonist of the Wnt/β-catenin signaling pathway, was discovered as a potential therapeutic target for stimulating bone formation in osteoporosis. In this study, molecular docking was employed to predict the binding of 29 herbal compounds, which were reported as bone formation stimulators, to the loop2 region of sclerostin. Then, the 50 ns molecular dynamics (MD) simulation of the complexes between sclerostin and the top 10 hits obtained from molecular docking were carried out. Root mean square deviations (RMSDs) analysis of MD trajectories pointed out that all ligands-complexes remain stable throughout the duration of MD simulations. In addition, the molecular mechanics/generalized born surface area (MM/GBSA) binding free energy and energy decomposition analyses were determined. The results here suggested that baicalin is the most promising inhibitor of sclerostin. Interestingly, baicalin binds to sclerostin via the hydrophobic interaction with the amino acid residues on loop2 region but outside the Pro-Asn-Ala-Ile-Gly (PNAIG) motif, particularly the Arg-Gly-Lys-Trp-Trp-Arg (RGKWWR) motif. This finding could be a novel strategy for developing new sclerostin inhibitors in the future.Communicated by Ramaswamy H. Sarma.

Bortezomib prevents ovariectomy-induced osteoporosis in mice by inhibiting osteoclast differentiation

Bone homeostasis is achieved through coordinated activities of bone-forming osteoblasts and bone-resorbing osteoclasts. When the balance is skewed in favor of osteoclasts due to hormonal or inflammatory issues, pathologic bone loss occurs leading to conditions such as osteoporosis, rheumatoid arthritis, and periodontitis. Bortezomib is the first in-class of proteasome inhibitors used as an anti-myeloma agent. In the present study, we show that bortezomib directly inhibited the receptor activator of nuclear factor κB ligand (RANKL)-dependent osteoclast differentiation of mouse bone marrow macrophages. Bortezomib significantly reduced the induction of osteoclast marker genes and proteins including nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1). The intraperitoneal injection of bortezomib reduced ovariectomy-induced osteoclastogenesis and protected the mice from bone loss. These data propose novel use of bortezomib as a potential anti-resorptive agent.

Clinical efficacy and safety of denosumab in postmenopausal women with low bone mineral density and osteoporosis: a meta-analysis

OBJECTIVE

Clinical trials indicate that denosumab could be a potential treatment for postmenopausal osteoporosis. The objective of this meta-analysis was to assess the clinical efficacy and safety of offering denosumab to postmenopausal women with low bone mass.

METHODS

Data sources included MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) from inception to February 3, 2010 and bibliographies of reviews. Randomized controlled trials comparing the efficacy and safety of denosumab to placebo for treatment of low bone mass (low bone mineral density or osteoporosis) in postmenopausal women were selected. Two reviewers independently abstracted data on study general characteristics and outcomes. Review Manager 5.0 software was used for data syntheses and meta-analysis.

RESULTS

The database search revealed 4 studies (comprising 8864 patients randomized) that met the inclusion criteria and contributed to some or all of the meta-analysis outcomes. Relative risk (95% CI) of fractures for the denosumab compared with placebo group was 0.58 (0.52 to 0.66); relative risk (95% CI) of serious adverse events was 1.33 (0.83 to 2.14); relative risk (95% CI) of serious adverse events related to infection was 2.10 (0.64 to 6.90); relative risk (95% CI) of neoplasm was 1.11 (0.91 to 1.36); relative risk (95% CI) of study discontinuation due to adverse events was 1.10 (0.83 to 1.47); and relative risk (95% CI) of death was 0.78 (0.57 to 1.06). Findings remained robust to sensitivity analyses.

CONCLUSION

Our analysis found a significant reduction in relative fracture risk in the denosumab compared with the placebo group.