Clinical role of bisphosphonate therapy

Vascular Calcification in Chronic Kidney Disease: An Update and Perspective

Chronic kidney disease is a devastating condition resulting from irreversible loss of nephron numbers and function and leading to end-stage renal disease and mineral disorders. Vascular calcification, an ectopic deposition of calcium-phosphate salts in blood vessel walls and heart valves, is an independent risk factor of cardiovascular morbidity and mortality in chronic kidney disease. Moreover, aging and related metabolic disorders are essential risk factors for chronic kidney disease and vascular calcification. Marked progress has been recently made in understanding and treating vascular calcification in chronic kidney disease. However, there is a paucity of systematic reviews summarizing this progress, and investigating unresolved issues is warranted. In this systematic review, we aimed to overview the underlying mechanisms of vascular calcification in chronic kidney diseases and discuss the impact of chronic kidney disease on the pathophysiology of vascular calcification. Additionally, we summarized potential clinical diagnostic biomarkers and therapeutic applications for vascular calcification with chronic kidney disease. This review may offer new insights into the pathogenesis, diagnosis, and therapeutic intervention of vascular calcification.

Breast Cancer Bone Metastasis: A Narrative Review of Emerging Targeted Drug Delivery Systems

Bone is one of the most common metastatic sites among breast cancer (BC) patients. Once bone metastasis is developed, patients' survival and quality of life will be significantly declined. At present, there are limited therapeutic options for BC patients with bone metastasis. Different nanotechnology-based delivery systems have been developed aiming to specifically deliver the therapeutic agents to the bone. The conjugation of targeting agents to nanoparticles can enhance the selective delivery of various payloads to the metastatic bone lesion. The current review highlights promising and emerging advanced nanotechnologies designed for targeted delivery of anticancer therapeutics, contrast agents, photodynamic and photothermal materials to the bone to achieve the goal of treatment, diagnosis, and prevention of BC bone metastasis. A better understanding of various properties of these new therapeutic approaches may open up new landscapes in medicine towards improving the quality of life and overall survival of BC patients who experience bone metastasis.

STING suppresses bone cancer pain via immune and neuronal modulation

Patients with advanced stage cancers frequently suffer from severe pain as a result of bone metastasis and bone destruction, for which there is no efficacious treatment. Here, using multiple mouse models of bone cancer, we report that agonists of the immune regulator STING (stimulator of interferon genes) confer remarkable protection against cancer pain, bone destruction, and local tumor burden. Repeated systemic administration of STING agonists robustly attenuates bone cancer-induced pain and improves locomotor function. Interestingly, STING agonists produce acute pain relief through direct neuronal modulation. Additionally, STING agonists protect against local bone destruction and reduce local tumor burden through modulation of osteoclast and immune cell function in the tumor microenvironment, providing long-term cancer pain relief. Finally, these in vivo effects are dependent on host-intrinsic STING and IFN-I signaling. Overall, STING activation provides unique advantages in controlling bone cancer pain through distinct and synergistic actions on nociceptors, immune cells, and osteoclasts.

Binding Immunoglobulin Protein (BIP) Inhibits TNF-α-Induced Osteoclast Differentiation and Systemic Bone Loss in an Erosive Arthritis Model

Objective

The association between inflammation and dysregulated bone remodeling is apparent in rheumatoid arthritis and is recapitulated in the human tumor necrosis factor transgenic (hTNFtg) mouse model. We investigated whether extracellular binding immunoglobulin protein (BiP) would protect the hTNFtg mouse from both inflammatory arthritis as well as extensive systemic bone loss and whether BiP had direct antiosteoclast properties in vitro.

Methods

hTNFtg mice received a single intraperitoneal administration of BiP at onset of arthritis. Clinical disease parameters were measured weekly. Bone analysis was performed by microcomputed tomography and histomorphometry. Mouse bone marrow macrophage and human peripheral blood monocyte precursors were used to study the direct effect of BiP on osteoclast differentiation and function in vitro. Monocyte and osteoclast signaling was analyzed by Western blotting, flow cytometry, and imaging flow cytometry.

Results

BiP-treated mice showed reduced inflammation and cartilage destruction, and histomorphometric analysis revealed a decrease in osteoclast number with protection from systemic bone loss. Abrogation of osteoclast function was also observed in an ex vivo murine calvarial model. BiP inhibited differentiation of osteoclast precursors and prevented bone resorption by mature osteoclasts in vitro. BiP also induced downregulation of CD115/c-Fms and Receptor Activator of NF-κB (RANK) messenger RNA and protein, causing reduced phosphorylation of the p38 mitogen-activated protein kinases, extracellular signal-regulated kinases 1/2 and p38, with suppression of essential osteoclast transcription factors, c-Fos and NFATc1. BiP directly inhibited TNF-α- or Receptor Activator of NF-κB Ligand (RANKL)-induced NF-κB nuclear translocation in THP-1 monocytic cells and preosteoclasts by the canonical and noncanonical pathways.

Conclusion

BiP combines an anti-inflammatory function with antiosteoclast activity, which establishes it as a potential novel therapeutic for inflammatory disorders associated with bone loss.

Role of Bisphosphonates in Vascular calcification and Bone Metabolism: A Clinical Summary

Background:

Vascular calcification is known to be a strong risk factor for cardiovascularadverse events and mortality. Atherosclerosis, diabetes, aging, abnormal bone mineral homeostasisand high uremic milieu such as chronic kidney disease are major factors that contribute to theprogression of vascular calcification. Several mechanisms such as the osteoblastic transition of vascularsmooth muscle cells in response to oxidative stress have shed light on the active nature ofvascular calcification, which was once thought to be a passive process. The fine interplay of regulatoryfactors such as PTH, vitamin D3, FGF 23 and klotho reflect the delicate balance between vascularcalcification and bone mineralization. Any disturbance affecting this equilibrium of the bonemineral-vascular axis results in accelerated vascular calcification.

Bisphosphonates share similar mechanism of action as statins, and hence several studies were undertakenin humans to verify if the benefits proven to be obtained in animal models extended tohuman models too. This yielded conflicting outcomes which are outlined in this review. This wasattributed mainly to inadequate sample size and flaws in the study design. Therefore, this benefitcan only be ascertained if studies addressing this are undertaken.

Conclusion:

This review seeks to highlight the pathophysiologic phenomena implicated in vascular and valvular calcification and summarize the literature available regarding the use of bisphosphonates in animal and human models. We also discuss novel treatment approaches for vascular calcification,with emphasis on chronic kidney disease and calciphylaxis.

Cytoprotective effect of flavonoid-induced autophagy on bisphosphonate mediated cell death in osteoblast

With rapid economic growth and further developments in medical science, the entry into the aging population is currently increasing, as is the number of patients with metabolic diseases, such as hypertension, hyperlipidemia, heart disease, and diabetes. The current treatments for metabolic bone diseases, which are also on the rise, cause negative side effects. Bisphosphonates, which are used to treat osteoporosis, inhibit the bone resorption ability of osteoclasts and during prolonged administration, cause bisphosphonate‐related osteonecrosis of the jaw (BRONJ). Numerous studies have shown the potential role of natural plant products as flavonoids in the protection against osteoporosis and in the influence of bone remodeling. Autophagy occurs after the degradation of cytoplasmic components within the lysosome and serves as an essential cytoprotective response to pathologic stress caused by certain diseases. In the present study, we hypothesized that the cytoprotective effects of flavonoids might be related to those associated with autophagy, an essential cytoprotective response to the pathologic stress caused by certain diseases, in osteoblasts. We demonstrated the cytoprotective effect of flavonoid‐induced autophagy against the toxicity of zoledronate and the induction of autophagy by flavonoids to support osteogenic transcription factors, leading to osteoblast differentiation and bone formation. Further studies are necessary to clarify the connections between autophagy and osteogenesis. It would be helpful to shed light on methodological challenges through molecular biological studies and new animal models. The findings of the current study may help to delineate the potential role of flavonoids in the treatment of metabolic bone disease.

Short-Term Safety of Zoledronic Acid in Young Patients With Bone Disorders: An Extensive Institutional Experience

CONTEXT

Zoledronic acid (ZA) is increasingly used in young patients with bone disorders. However, data related to the safety of ZA administration in this population are limited.

OBJECTIVE

The study aimed to characterize the short-term safety profile of ZA and identify risk factors for ZA-related adverse events (AEs) in young patients.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective chart review of inpatients and outpatients less than 21 years old who received at least one ZA infusion between July 2010 and January 2014 at The Children's Hospital of Philadelphia.

RESULTS

Eighty-one patients (56% male; median age, 12 y; age at first infusion, 0.5 to 20 y) with diverse skeletal disorders received a total of 204 infusions. The most common indications were osteoporosis (33% of cohort) and osteogenesis imperfecta (27.2%). The median ZA dose was 0.025 mg/kg (interquartile range, 0.025-0.05); the median dosing interval was 6 months (range, 1 to 25.6 mo). AEs were mild and more common after the first ZA infusion in patients with no previous bisphosphonate exposure: hypophosphatemia (25.2% of infusions), acute phase reactions (19.1%), and hypocalcemia (16.4%). Symptomatic hypocalcemia requiring iv calcium occurred after two infusions. ZA dose was significantly associated with hypophosphatemia, but not other AEs. Hypocalcemia was more common in patients with high bone turnover as assessed by preinfusion alkaline phosphatase levels. AEs were not associated with diagnosis, baseline serum calcium, or calcium/calcitriol supplementation.

CONCLUSION

Acute AEs related to ZA infusion in youths are common, occur principally after the first ZA infusion in bisphosphonate-naive patients, and are typically mild and easily managed. Future prospective studies are needed to determine the potential long-term risks, as well as benefits, of ZA therapy in the pediatric population.

A polymorphism at the translation start site of the vitamin D receptor gene is associated with the response to anti-osteoporotic therapy in postmenopausal women from southern Italy

The present study investigated the effect of two single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) gene, rs1544410 A/G and rs2228570 C/T, in modulating bone mineral density (BMD) and the response to treatment with bisphosphonates or strontium ranelate in postmenopausal osteoporosis (PMO). Four hundred eighteen postmenopausal women from Southern Italy treated with bisphosphonates or strontium ranelate for three years were enrolled and stratified according to their genotype. Changes in BMD were expressed as the delta t-score (Δt-score). Allelic frequencies for rs1544410 A/GSNP were 11.2% AA, 50.0% GA and 38.8% GG; for rs2228570 C/TSNP were 54.8% CC, 39.5% TC and 5.7% TT. TT carriers showed a lower t-score than TC and CC (both p < 0.02) genotypes and were more responsive to the therapy when compared to both TC (p < 0.02) and CC (p < 0.05) carriers. Specifically, TT carriers receiving alendronate demonstrated a significant improvement of the Δt-score compared to TC and CC (both p < 0.0001) carriers. After adjustment for confounders, the Δt-score showed evidence of a statistically significant positive association with TT in all treatments considered. Therapy response was independent of rs1544410 A/G SNP; instead, rs2228570 C/TSNP was associated with a better response to antiresorptive treatment, thus suggesting that the therapy for PMO should be personalized.

Treatment of post-menopausal osteoporosis: beyond bisphosphonates

Osteoporosis is a highly prevalent condition, characterized by compromised bone strength and fragility fractures and with an important associated socio-economic burden. Bisphosphonates are well established as the first line treatment for osteoporosis. However, while randomized control trials have in general demonstrated reasonable anti-fracture efficacy at the spine, they have shown moderate reduction in fracture incidence for non-vertebral sites. Furthermore, oral bisphosphonates are commonly associated with adverse gastrointestinal effects and both oral and parenteral bisphosphonates have been linked with osteonecrosis of the jaw and atypical femoral fracture, two rare but debilitating side effects. In addition, bisphosphonates are not recommended in patients with GFR <35 ml/min/1.73 m(2). Hence, there is a clear requirement for newer agents, which are able to reduce fracture risk further, whilst overcoming the limitations of bisphosphonates. Over the past 20 years, knowledge and a deeper understanding of the various signalling pathways involved in bone remodelling has increased, enabling identification of additional targets for therapy. This review focuses on these newer therapies and includes anti-resorptive agents such as raloxifene and other selective oestrogen receptor modulators, the monoclonal antibody denosumab (which inhibits the RANKL pathway), odanacatib, a cathepsin K inhibitor and the anabolic agents, PTH analogue; PTH (1-34) and anti-sclerostin antibodies (activator of the Wnt pathway). Strontium ranelate will not be reviewed as recent reports highlight concerns surrounding its cardiovascular safety and together with an apparent increased risk of thrombosis, its future use remains uncertain. Some of these agents such as raloxifene, denosumab and teriparatide are already in clinical use whilst others are at varying stages of development. This review will provide an overview of the mechanisms of action of these therapeutic agents on the skeleton and assess their efficacy in osteoporosis and fracture prevention.

Current studies of acupuncture in cancer-induced bone pain animal models

Acupuncture is generally accepted as a safe and harmless treatment option for alleviating pain. To explore the pain mechanism, numerous animal models have been developed to simulate specific human pain conditions, including cancer-induced bone pain (CIBP). In this study, we analyzed the current research methodology of acupuncture for the treatment of CIBP. We electronically searched the PubMed database for animal studies published from 2000 onward using these search terms: (bone cancer OR cancer) AND (pain OR analgesia) AND (acupuncture OR pharmacopuncture OR bee venom). We selected articles that described cancer pain in animal models. We analyzed the methods used to induce cancer pain and the outcome measures used to assess the effects of acupuncture on CIBP in animal models. We reviewed articles that met our inclusion criteria. Injection of mammary cancer cells into the cavity of the tibia was the most frequently used method for inducing CIBP in the animal models. Among the eight selected studies, five studies demonstrated the effects of electroacupuncture on CIBP. The effects of acupuncture were assessed by measuring pain-related behavior. Future researches will be needed to ascertain the effectiveness of acupuncture for treating CIBP and to explore the specific mechanism of CIBP in animal models.

Implant failure caused by non-union of bisphosphonate-associated subtrochanteric femur fracture

Bisphosphonate use has been identified as a contributory factor in atypical subtrochanteric fracture of the femur. These fractures are commonly treated with an intramedullary device. We present a case of implant failure of an intrameduallary device caused by non-union of an atypical subtrochanteric fracture.

Altered bone development in a mouse model of peripheral sensory nerve inactivation

OBJECTIVES

The present study sought to determine the effects of decreased peripheral sensory nerve function on skeletal development and bone metabolism in mice.

METHODS

C57BL/6 neonatal mice were treated with capsaicin to induce peripheral sensory nerve degeneration, and compared to vehicle-treated controls at 4, 8 and 12 weeks of age. Changes in bone structure were assessed using micro-computed tomography, mechanical properties and fracture resistance were assessed using three-point bending of radii, and bone turnover was assessed using dynamic histomorphometry and serum biomarkers.

RESULTS

Capsaicin treatment resulted in small but significant decreases in bone structure, particularly affecting trabecular bone. Capsaicin-treated mice exhibited lower trabecular thickness at the femoral metaphysis and L5 vertebral body compared with vehicle-treated mice. However, capsaicin- and vehicle-treated mice had similar mechanical properties and bone turnover rates.

CONCLUSION

Neonatal capsaicin treatment affected trabecular bone during development; however these small changes may not be meaningful with respect to bone strength under normal loading conditions. It is possible that capsaicin-sensitive neurons may be more important for bone under stress conditions such as increased mechanical loading or injury. Future studies will investigate this potential role of peripheral sensory nerves in bone adaptation.

The association between serious upper gastrointestinal bleeding and incident bisphosphonate use: a population-based nested cohort study

Background

Oral bisphosphonates are commonly used to prevent / treat osteoporosis. However, bisphosphonate treatment is not without risk and serious adverse effects, including upper gastrointestinal bleeding (UGIB) have been described. We sought to determine if new users of bisphosphonate drugs were more likely to suffer a serious UGIB within 120 days of drug initiation.

Methods

This was a population-based nested cohort study utilizing administrative healthcare data in British Columbia, Canada. Community based individuals ≥ 65 years with a new prescription for a bisphosphonate between 1991 and 2007 were included. A multivariate logistic regression model was used to examine the relationship between older age and the development of a serious UGIB within 120 days of new exposure to oral bisphosphonate drugs.

Results

Within the exposure cohort (n = 26,223), 117 individuals had suffered a serious UGIB within 120 days of incident bisphosphonate use. Cases tended to be > 80 years old, and were significantly more likely to have had a past history of gastric ulcer disease, a remote history of serious UGIB, and had been dispensed proton pump inhibitor (PPI) medications (p < 0.001 for all comparisons). After adjustment for confounding covariates, those > 80 years were more than twice as likely to suffer a UGIB when compared to those ≤ 80 years (adjusted OR = 2.03; 95% CI 1.40–2.94). A past history of serious UGIB was the strongest predictor of UGIB within 120 days of incident bisphosphonate use (adjusted OR = 2.28; 95% CI = 1.29–4.03) followed by PPI use (adjusted OR = 2.04; 95% CI = 1.35–3.07). Males were 70% more likely to suffer an UGIB compared to females (adjusted OR = 1.69; 95% CI = 1.05–2.72).

Conclusions

Upper GIB is a rare, but serious, side effect of bisphosphonate therapy more often afflicting older individuals. At the same time, concern about potential rare adverse events should not discourage clinicians from prescribing bisphosphonate drugs, particularly in older patients who have already sustained a fragility fracture. Clinicians must remain cognizant of potential adverse events associated with bisphosphonate use and should routinely ask about pre-existing GI disorders and concurrent medication history prior to prescribing these drugs.