Denosumab in postmenopausal osteoporosis: what the clinician needs to know

Protaetia brevitarsis seulensis larvae ethanol extract inhibits RANKL-stimulated osteoclastogenesis and ameliorates bone loss in ovariectomized mice

Modulation of osteoclast formation could be a therapeutic target for inhibiting pathological bone destruction. The receptor activator of nuclear factor (NF)-κB ligand (RANKL) is known to be an essential factor in osteoclast differentiation and activation inducers. However, whether Protaetia brevitarsis seulensis (P. brevitarsis) larvae-a traditional animal-derived medicine used in many Asian countries-can inhibit RANKL-induced osteoclast formation and prevent ovariectomy (OVX)-induced bone loss has not been evaluated. Here, we aimed to investigate the anti-osteoporotic effects of P. brevitarsis larvae ethanol extract (PBE) in RANKL-stimulated RAW264.7 cells and OVX mice. In vitro, PBE (0.1, 0.5, 1, and 2 mg/mL) decreased RANKL‑induced tartrate-resistant acid phosphatase (TRAP) activity and expression of osteoclastogenesis-associated genes and proteins. Furthermore, PBE (0.1, 0.5, 1, and 2 mg/mL) significantly inhibited the phosphorylation of p38 and NF-κB. Female C3H/HeN mice were divided into five groups (n = 5 per group), namely, sham-operated, OVX, OVX+PBEL (100 mg/kg, oral gavage), OVX+PBEH (200 mg/kg, oral gavage), and OVX+estradiol (0.03 μg/day, subcutaneous injection). High doses of PBE significantly increased femoral bone mineral density (BMD) and bone volume/tissue volume (BV/TV), whereas femoral bone surface/bone volume (BS/BV) and osteoclastogenesis-associated protein expression decreased compared to those in the OVX group. Moreover, PBE (200 mg/kg) significantly increased estradiol and procollagen type I N-terminal propeptide and decreased N-terminal telopeptide of type I collagen and C-terminal telopeptide of type I collagen compared to those in the OVX group. Our results suggest that PBE can be an effective therapeutic candidate for preventing or treating postmenopausal osteoporosis.

Risk factors for poor response to denosumab treatment in Japanese postmenopausal women with osteoporosis

INTRODUCTION

Denosumab has been reported to increase bone mineral density (BMD) and suppress fractures, but poor responders are not uncommon. This study aimed to identify risk factors for poor response to denosumab treatment. This is the first study to explore risk factors for poor response to denosumab.

MATERIALS AND METHODS

This retrospective observational study investigated 227 Japanese postmenopausal women who received denosumab with monitoring of BMD by dual-energy X-ray absorptiometry at 6-month intervals. Risk factors were identified using Cox's proportional hazard modeling. Poor responders were defined as not exceeding the least significant change of BMD from baseline for 3 years.

RESULTS

Mean relative change from baseline for 3 years in lumbar spine (LS)-BMD, femoral neck (FN)-BMD, and total hip (TH)-BMD were 12.6%, 6.8%, and 6.1%, respectively. Numbers of poor responders were 10 in LS-BMD, 47 in FN-BMD, 38 in TH-BMD. Risk factors for poor response were concomitant glucocorticoid use for LS-BMD, low body mass index or initiation at higher BMD for FN-BMD, and pretreatment with bisphosphonates or initiation at higher BMD for TH-BMD.

CONCLUSION

Risk factors for insufficient denosumab effect differed between BMD measurement sites. These results should be taken into consideration when selecting denosumab in clinical practice.

Cancer Treatment-Induced Bone Loss: Role of Denosumab in Non-Metastatic Breast Cancer

Chemotherapeutic agents, endocrine therapy and radiotherapy used in the management of breast cancer are known to cause decreased bone mineral density, and thus, increased incidence of fractures. A majority (~60%) of the breast cancer patients in India are either estrogen (ER) or progesterone hormone receptor (PR) positive. Adjuvant treatment with aromatase inhibitors (AIs) is the treatment mainstay for hormone-sensitive disease in postmenopausal (PM) women, with reduced bone mineral density (BMD), which results in increased fracture rates. Zoledronic acid, alendronate, risedronate and denosumab have been the agents of choice for managing bone loss. Denosumab 60 mg is approved for gaining bone mass in women with breast cancer who are at high risk for fracture following adjuvant AI treatment. The phase III HALT-BC data indicate an improvement in BMD with denosumab and a 50% reduction in clinical fractures, with significant improvements seen at the lumbar spine, distal third of the radius, and total hip. Denosumab has several advantages over other bone modifying agents such as subcutaneous self-administration by the patient themselves, no requirement of hospitalization, no dose modifications in renal impairment, and low incidence of acute phase anaphylactic reactions. We review the available evidence of denosumab for managing bone loss in non-metastatic breast cancer patients.

Identification of Potential Therapeutic Targets and Molecular Regulatory Mechanisms for Osteoporosis by Bioinformatics Methods

BACKGROUND

Osteoporosis is characterized by low bone mass, deterioration of bone tissue structure, and susceptibility to fracture. New and more suitable therapeutic targets need to be discovered.

METHODS

We collected osteoporosis-related datasets (GSE56815, GSE99624, and GSE63446). The methylation markers were obtained by differential analysis. Degree, DMNC, MCC, and MNC plug-ins were used to screen the important methylation markers in PPI network, then enrichment analysis was performed. ROC curve was used to evaluate the diagnostic effect of osteoporosis. In addition, we evaluated the difference in immune cell infiltration between osteoporotic patients and control by ssGSEA. Finally, differential miRNAs in osteoporosis were used to predict the regulators of key methylation markers.

RESULTS

A total of 2351 differentially expressed genes and 5246 differentially methylated positions were obtained between osteoporotic patients and controls. We identified 19 methylation markers by PPI network. They were mainly involved in biological functions and signaling pathways such as apoptosis and immune inflammation. HIST1H3G, MAP3K5, NOP2, OXA1L, and ZFPM2 with higher AUC values were considered key methylation markers. There were significant differences in immune cell infiltration between osteoporotic patients and controls, especially dendritic cells and natural killer cells. The correlation between MAP3K5 and immune cells was high, and its differential expression was also validated by other two datasets. In addition, NOP2 was predicted to be regulated by differentially expressed hsa-miR-3130-5p.

CONCLUSION

Our efforts aim to provide new methylation markers as therapeutic targets for osteoporosis to better treat osteoporosis in the future.

4-Hexylresorcinol inhibits osteoclastogenesis by suppressing the NF-κB signaling pathway and reverses bone loss in ovariectomized mice

4-Hexylresorcinol (4HR) is a small organic compound that is widely used as an antiseptic and antioxidant. In the present study, its role in osteoclastogenesis was investigated. Bone marrow-derived macrophages from mice were used to examine the role of 4HR in osteogenesis. An ovariectomy (OVX) mouse model was constructed to examine the effect of 4HR in vivo, followed by hematoxylin and eosin and tartrate resistant acid phosphatase staining. In the present study, 4HR effectively suppressed receptor activator of NF-κB ligand-induced osteoclastogenesis in a dose-dependent manner. 4HR was also found to significantly suppress the expression of osteoclast (OC)-specific markers, including tartrate-resistant acid phosphatase, cathepsin K, nuclear factor of activated T-cell cytoplasmic 1 and c-Fos in the presence of RANKL in BMMs. Furthermore, 4HR inhibited osteoclastogenesis by inhibiting the activation of the NF-κB signaling pathway in BMMs. Consistent with the in vitro results, 4HR effectively ameliorated OVX-induced bone loss and markedly reduced OC number in the proximal tibia in vivo. In conclusion, the present results suggested that 4HR inhibited osteoclastogenesis in vitro and rescued bone loss in vivo, suggesting that 4HR may serve as a novel therapeutic agent for osteoporosis treatment.

Medication-Related Osteonecrosis of the Jaw (MRONJ): Are Antiresorptive Drugs the Main Culprits or Only Accomplices? The Triggering Role of Vitamin D Deficiency

Osteonecrosis of the jaw (ONJ) is a severe clinical condition characterized mostly but not exclusively by an area of exposed bone in the mandible and/or maxilla that typically does not heal over a period of 6-8 weeks. The diagnosis is first of all clinical, but an imaging feedback such as Magnetic Resonance is essential to confirm clinical suspicions. In the last few decades, medication-related osteonecrosis of the jaw (MRONJ) has been widely discussed. From the first case reported in 2003, many case series and reviews have appeared in the scientific literature. Almost all papers concerning this topic conclude that bisphosphonates (BPs) can induce this severe clinical condition, particularly in cancer patients. Nevertheless, the exact mechanism by which amino-BPs would be responsible for ONJ is still debatable. Recent findings suggest a possible alternative explanation for BPs role in this pattern. In the present work we discuss how a condition of osteomalacia and low vitamin D levels might be determinant factors.

Osteoporosis: Current and Emerging Therapies Targeted to Immunological Checkpoints

Osteoporosis is a skeletal pathology characterized by compromised bone strength leading to increased risk of fracture, mainly the spine and hip fractures. Osteoporosis affects more than 200 million people worldwide and because of the skeletal fractures it causes, represents a major cause of morbidity, disability and mortality in older people. Recently, the new discoveries of osteoimmunology have clarified many of the pathogenetic mechanisms of osteoporosis, helping to identify new immunological targets for its treatment opening the way for new and effective therapies with biological drugs. Currently, there are basically two monoclonal antibodies for osteoporosis therapy: denosumab and romosozumab. Here, we focus on the modern approach to the osteoporosis management and in particular, on current and developing biologic drugs targeted to new immunological checkpoints, in the landscape of osteoimmunology.

New and emerging concepts in the use of denosumab for the treatment of osteoporosis

Denosumab is a fully human monoclonal antibody to receptor activator of nuclear factor kappa-B ligand (RANKL), a cytokine expressed by cells of the osteoblast lineage that is a key regulator of osteoclastic bone resorption. By binding and neutralizing RANKL, denosumab inhibits osteoclast differentiation, activity, and survival. Clinical trials in postmenopausal women with osteoporosis have shown that it reduces the risk of vertebral fractures, nonvertebral fractures, and hip fractures, with a generally favorable safety profile. With a dose of 60 mg subcutaneously every 6 months, it is approved for: treatment of postmenopausal women and men with osteoporosis, and for women and men with glucocorticoid-induced osteoporosis who are at high risk for fracture; treatment to increase bone mass in men at high risk for fracture receiving androgen-deprivation therapy for nonmetastatic prostate cancer; and treatment to increase bone mass in women at high risk for fracture receiving adjuvant aromatase inhibitor therapy for breast cancer. Atypical femur fractures and osteonecrosis of the jaw have been reported in patients treated with denosumab. Discontinuation of denosumab is followed by rapidly rising bone turnover markers, decreasing bone density, and vertebral fracture risk that returns to baseline, with a possible increase in the risk of multiple vertebral fractures. Further study is needed to clarify this potential risk. After stopping long-term denosumab, patients should be switched to another antiresorptive agent to maintain the benefit achieved with denosumab.

Osteoprotegerin and uremic osteoporosis in chronic hemodialysis patients

INTRODUCTION

Osteoprotegerin (OPG) is a powerful inhibitor of osteoclast activity, and it plays an important role in bone metabolism. In hemodialysis (HD) patients, the relationship between OPG and bone mineral density (BMD) is important, but remains unclear yet. The study objective was to assess the OPG role related to uremic osteoporosis in HD patients.

METHODS

This cross-sectional study has been realized on a cohort of 63 chronic HD patients.

INCLUSION CRITERIA

elderly prevalent HD patients with an age over 55 years old.

EXCLUSION CRITERIA

previous bone disease or previous renal transplant; neoplasia; parathyroidectomy, hormone replacement therapy. The data regarding demographical and clinical characteristics, including treatments for mineral and cardiovascular complications, were recorded. Serum OPG and mineral markers levels were measured. BMD was assessed by calcaneus quantitative ultrasound; it measured broadband ultrasound attenuation, speed of sound (SOS) and stiffness index (STI).

RESULTS

The high OPG levels were associated with higher bone mineral density (OPG-SOS P = 0.003; R = 0.37; OPG-STI P = 0.03; R = 0.28). Malnutrition, anemia and advanced age correlated with bone demineralization. Males had higher bone density parameters than females. In patients treated with vitamin D (P = 0.005), the BMD was increased comparing to patients without these treatments.

CONCLUSIONS

OPG levels had directly correlated with bone mineral density parameters. Our study further confirms the critical role of OPG in the pathogenesis of uremic osteoporosis in ESRD. Whether the increased circulant OPG protect against bone loss in patients undergoing HD remains to be established.

Denosumab: A New Injectable Treatment for Postmenopausal Osteoporosis

Background/Introduction:

Osteoporosis results in a significant increase in fractures, leading to morbidity and mortality. Adherence is a concern with commonly used antiresorptive agents, the bisphosphonates. Denosumab, which inhibits bone resorption by a different mechanism and is administered subcutaneously every 6 months, may provide an advantage in decreasing fracture risk in those with osteoporosis.

Objective:

To review the available data with respect to the mechanism of action, efficacy and safety of denosumab for the management of postmenopausal osteoporosis.

Methods:

Several databases were searched to identify phase III randomized controlled trials (RCT) that examined the effect of denosumab on bone mineral density (BMD) and/or fracture rate and the safety of denosumab in the management of postmenopausal osteoporosis.

Results:

In 2 of the 4 trials identified, denosumab was significantly better than placebo at increasing BMD, and in 1 trial reduced the risk of vertebral, nonvertebral and hip fractures. No head-to-head trials comparing fracture risk reduction of denosumab to bisphosphonates were found, however, 2 trials did report increased BMD with denosumab compared to alendronate. In the 4 studies reviewed, adverse effects reported more frequently with denosumab included rash and eczema, as well as bronchitis and influenza-like illness. There is potential for an increased risk of other infections and malignancies.

Conclusions:

The results of RCT trials suggest that denosumab is effective at maintaining or increasing BMD compared to placebo or alendronate in women with either osteopenia or osteoporosis and in 1 trial demonstrated a significant reduction in fracture rate compared to placebo. Overall, denosumab appeared to be well tolerated in the studies reviewed. Continued monitoring is needed to determine long-term safety and efficacy.

Osteoporosis: New-Generation Drugs

A new understanding in the pathophysiology of bone led to the development of a fully human monoclonal antibody directed against RANK ligand (RANKL). Denosumab inhibits the interaction of RANKL with its receptor RANK, thereby suppressing osteoclast differentiation, function and survival. In this respect, denosumab mimics osteoprotegerin, the endogenous antagonist of RANKL. Recently, denosumab has been approved by the European Medicines Agency (EMEA) for the treatment of postmenopausal osteoporosis (PMO) and treatment-induced bone loss in breast and prostate cancer patients undergoing hormone ablation. Oncologic indications affecting bone are promising, but still under clinical evaluation. In clinical trials for PMO, denosumab has shown significant increases in bone mineral density (BMD) at various skeletal sites, decreases in bone turnover markers, and reductions in fracture risk. In head-tohead studies, denosumab proved to be superior to alendronate with regard to the increase in BMD. Considering clinical trial data, the risk-benefit profile of denosumab seems to be favorable since the rates of adverse events, serious adverse events, infections, malignancies and deaths were not higher compared to the control arms. In PMO, denosumab is applied subcutaneously as a 60-mg dose twice yearly. This administration scheme and route might have a high acceptance by patients and physicians.