An open-label, prospective pilot clinical study of denosumab for severe hyperparathyroidism in patients with low bone mass undergoing dialysis

Is denosumab an efficient and safe drug for osteoporosis in dialysis patients? Considerations and state of the art about its use in this setting

PURPOSE

In patients with chronic kidney disease (CKD), renal osteodystrophy may be associated with a progressive bone mass loss that increases fracture risk. Denosumab, a monoclonal antibody inhibiting osteoclast activity, is an antiresorptive medication used for the treatment osteoporosis.

METHODS

Its efficacy and safety were initially established in the FREEDOM study, showing a significant reduction in incident fractures in osteoporotic women treated with denosumab. Subsequent post hoc analyses showed its efficacy in patients stratified by kidney function, but these analyses did not include patients with advanced stages of CKD. The capability of denosumab in improving bone mineral density in uremic patients was evaluated in 12 studies including 461 dialysis patients with low bone mineral density. The improvement of bone mineral density was the final end point in these studies assessed during a follow-up of 6-60 months. Nine of these studies did not have hyperparathyroidism among criteria for patient inclusion and their participants may have low-turnover bone disease. Despite current recommendations, no patients underwent bone biopsy before denosumab therapy.

RESULTS

Overall, findings in these studies suggest that denosumab is a viable option for promoting bone mass recovery in patients with advanced stages of CKD having either high or low serum levels of PTH. However, the increase of bone mineral density was lower in patients with low serum markers of bone turnover at baseline. These studies also highlighted the need for calcium and vitamin D supplementation to prevent hypocalcemia that remains a serious concern.

CONCLUSIONS

Denosumab emerges as a potentially safe and effective option for enhancing bone health in CKD patients.

Long-term effects of denosumab on bone mineral density and turnover markers in patients undergoing hemodialysis

INTRODUCTION

Denosumab, a fully human anti-RANKL monoclonal antibody, is a widely used osteoporosis treatment that is increasingly being used in patients undergoing dialysis; however, its long-term efficacy and safety in these patients remain unknown.

MATERIALS AND METHODS

This observational study comprised individuals aged ≥ 20 years undergoing hemodialysis and receiving denosumab. After denosumab administration, we analyzed the long-term changes in bone mineral density (BMD) and levels of bone turnover markers (BTMs) and calcium.

RESULTS

The study included 45 patients who have been receiving denosumab for a median duration of 3.8 (interquartile range, 2.5-6.7) years. Tartrate-resistant acid phosphatase 5b (TRACP-5b) levels decreased from a median of 595 (434-778) mU/dL at baseline to 200 (141-430) mU/dL after 6 months of denosumab administration (P < 0.001) and remained low thereafter. Similarly, bone-specific alkaline phosphatase (BAP) levels decreased from a median of 18.2 (15.9-25.8) μg/L at baseline to 12.4 (9.9-15.6) μg/L after 6 months (P < 0.001) and remained low thereafter. Meanwhile, BMD, as assessed with dual energy X-ray absorptiometry and measured at the distal 1/3 of the radius, did not decrease (0.465 ± 0.112 g/cm2 at baseline vs. 0.464 ± 0.112 g/cm2 after administration; P = 0.616). Regarding hypocalcemia, corrected calcium levels reached were the lowest at 7 days after administration and normalized within 30 days.

CONCLUSION

The study showed long-term suppression of TRACP-5b and BAP levels and sustaining BMD after denosumab administration over an extended period in patients undergoing hemodialysis.

Severe Hypocalcemia With Denosumab Among Older Female Dialysis-Dependent Patients

Importance

Dialysis-dependent patients experience high rates of morbidity from fractures, yet little evidence is available on optimal treatment strategies. Chronic kidney disease-mineral and bone disorder is nearly universal in dialysis-dependent patients, complicating diagnosis and treatment of skeletal fragility.

Objective

To examine the incidence and comparative risk of severe hypocalcemia with denosumab compared with oral bisphosphonates among dialysis-dependent patients treated for osteoporosis.

Design, Setting, and Participants

Retrospective cohort study of female dialysis-dependent Medicare patients aged 65 years or older who initiated treatment with denosumab or oral bisphosphonates from 2013 to 2020. Clinical performance measures including monthly serum calcium were obtained through linkage to the Consolidated Renal Operations in a Web-Enabled Network database.

Exposures

Denosumab, 60 mg, or oral bisphosphonates.

Main Outcomes and Measures

Severe hypocalcemia was defined as total albumin-corrected serum calcium below 7.5 mg/dL (1.88 mmol/L) or a primary hospital or emergency department hypocalcemia diagnosis (emergent care). Very severe hypocalcemia (serum calcium below 6.5 mg/dL [1.63 mmol/L] or emergent care) was also assessed. Inverse probability of treatment-weighted cumulative incidence, weighted risk differences, and weighted risk ratios were calculated during the first 12 treatment weeks.

Results

In the unweighted cohorts, 607 of 1523 denosumab-treated patients and 23 of 1281 oral bisphosphonate-treated patients developed severe hypocalcemia. The 12-week weighted cumulative incidence of severe hypocalcemia was 41.1% with denosumab vs 2.0% with oral bisphosphonates (weighted risk difference, 39.1% [95% CI, 36.3%-41.9%]; weighted risk ratio, 20.7 [95% CI, 13.2-41.2]). The 12-week weighted cumulative incidence of very severe hypocalcemia was also increased with denosumab (10.9%) vs oral bisphosphonates (0.4%) (weighted risk difference, 10.5% [95% CI, 8.8%-12.0%]; weighted risk ratio, 26.4 [95% CI, 9.7-449.5]).

Conclusions and Relevance

Denosumab was associated with a markedly higher incidence of severe and very severe hypocalcemia in female dialysis-dependent patients aged 65 years or older compared with oral bisphosphonates. Given the complexity of diagnosing the underlying bone pathophysiology in dialysis-dependent patients, the high risk posed by denosumab in this population, and the complex strategies required to monitor and treat severe hypocalcemia, denosumab should be administered after careful patient selection and with plans for frequent monitoring.

Inhibition of RANKL improves the skeletal phenotype of adenine-induced chronic kidney disease in mice

Skeletal fragility and high fracture rates are common in CKD. A key component of bone loss in CKD with secondary hyperparathyroidism is high bone turnover and cortical bone deterioration through both cortical porosity and cortical thinning. We hypothesized that RANKL drives high bone resorption within cortical bone leading to the development of cortical porosity in CKD (study 1) and that systemic inhibition of RANKL would mitigate the skeletal phenotype of CKD (study 2). In study 1, we assessed the skeletal properties of male and female Dmp1-cre RANKLfl/fl (cKO) and control genotype (Ranklfl/fl; Con) mice after 10 wk of adenine-induced CKD (AD; 0.2% dietary adenine). All AD mice regardless of sex or genotype had elevated blood urea nitrogen and high PTH. Con AD mice in both sexes had cortical porosity and lower cortical thickness as well as high osteoclast-covered trabecular surfaces and higher bone formation rate. cKO mice had preserved cortical bone microarchitecture despite high circulating PTH as well as no CKD-induced increases in osteoclasts. In study 2, male mice with established AD CKD were either given a single injection of an anti-RANKL antibody (5 mg/kg) 8 wk post-induction of CKD or subjected to 3×/wk dosing with risedronate (1.2 μg/kg) for 4 wk. Anti-RANKL treatment significantly reduced bone formation rate as well as osteoclast surfaces at both trabecular and cortical pore surfaces; risedronate treatment had little effect on these bone parameters. In conclusion, these studies demonstrate that bone-specific RANKL is critical for the development of high bone formation/high osteoclasts and cortical bone loss in CKD with high PTH. Additionally, systemic anti-RANKL ligand therapy in established CKD may help prevent the propagation of cortical bone loss via suppression of bone turnover.

Effects of denosumab on bone mineral density and bone metabolism in patients with end-stage renal disease: A systematic review and meta-analysis

INTRODUCTION

The effects of denosumab on bone mineral density (BMD) and metabolism in patients with end-stage renal disease (ESRD) remain controversial. Hence, we performed a systematic review and meta-analysis of observational studies.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched in June 2022 to identify studies that evaluated the risk of denosumab-associated hypocalcemia and changes in bone metabolism, changes in BMD from baseline to post-treatment in patients with ESRD.

FINDINGS

Twelve studies with 348 participants were included. The pooled incidence of hypocalcemia during denosumab treatment was 35.0% (95% confidence interval [CI], 25%-46%; I2  = 63.6%). There were no significant changes in either the serum calcium or phosphate levels from the baseline to post-treatment period; the mean differences were 0.04 mg/dL (95% CI, -0.12 to 0.20 mg/dL) and -0.39 mg/dL (95% CI, -0.89 to 0.12 mg/dL). We found significant changes in the alkaline phosphatase and parathyroid hormone levels; the standardized mean differences were -2.98 (95% CI, -5.36 to -0.59) and -3.12 (95% CI: -4.94 to -1.29), respectively. Denosumab may increase BMD, with mean differences of 9.10% (95% CI: 4.07%-14.13%) and 9.00% (95% CI: 5.93%-12.07%) for the femoral neck and lumbar spine, respectively.

DISCUSSION

Denosumab increased the BMDs of the lumbar spine and femoral neck in patients with ESRD. The onset of hypocalcemia must be carefully monitored during denosumab administration.

Efficacy and safety of medications for osteoporosis in kidney transplant recipients or patients with chronic kidney disease: A meta-analysis

This study conducted a meta-analysis to analyze the efficacy and safety of osteoporosis medications in kidney transplant recipients and patients with chronic kidney disease (CKD). PubMed, Embase, the Cochrane Central Register of Controlled Trials were searched from the date of their inception through October 21, 2022. We performed a meta-analysis of the efficacy and safety of osteoporosis medications in adult patients with stage 3-5 CKD or kidney transplant recipients enrolled in randomized clinical trials (RCTs). We calculated the standard mean deviations with 95% confidence intervals (CI) for bone mineral density (BMD) and T scores after 6 and 12 months treatment, pooled odds ratio and 95% CI for fracture risk, and summarized adverse events. The inclusion criteria were met by 27 studies. Out of this, 19 studies were included for the meta-analysis. In stage 3-4 CKD patients, alendronate increased lumbar spine BMD. In patients at stage 5 CKD and undergoing hemodialysis, alendronate and raloxifene increased lumbar spine BMD. After 6 months, the BMD of kidney transplant recipients was seen to be significantly increased; however, there was no difference after 12 months, and the risk of fracture did not reduce. Thus, there is no evidence that these medications reduce the risk of fracture, and their effect on BMD and fracture remains unproven. These medications may increase the incidence of adverse events and their safety needs to be further evaluated. Therefore, we cannot draw a definitive conclusion about the efficacy and safety of osteoporosis medications in the above group of patients.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Integrated Osteoporosis Care to Reduce Denosumab-Associated Hypocalcemia for Patients with Advanced Chronic Kidney Disease and End-Stage Renal Disease

The incidence of hypocalcemia is high in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) undergoing denosumab treatment. Since 2018, we have carried out a "multidisciplinary integrated care program for osteoporosis among patients with CKD and ESRD" in our hospital. The aim of this study was to compare the incidence of denosumab-associated hypocalcemia among patients with advanced CKD and ESRD before and after the integrated care program. We retrospectively reviewed the records of patients on their first dose of denosumab treatment from January 2012 to December 2021. A total of 3208 patients were included in our study. Among the 3208 patients, there were 101 dialysis patients, 150 patients with advanced CKD (stage 4 and 5), and 2957 patients with an estimated glomerular filtration rate (eGFR) higher than or equal to 30. The incidence of post-treatment severe hypocalcemia (corrected calcium level less than 7.0 mg/dl) within 30 days was significantly higher in the dialysis and advanced CKD group than in patients with an eGFR higher than or equal to 30 (6.9% vs. 2.0% vs. 0.1%, respectively, p < 0.001). Based on the results of the multivariate regression model, poor renal function (p < 0.05) and lower baseline corrected calcium level (p < 0.05) were associated with severe hypocalcemia within 30 days following the first dose of denosumab treatment. The incidence of post-treatment severe hypocalcemia within 30 days in advanced CKD and dialysis patients was significantly lower after the integrated care program (6.8% vs. 0.8%, p < 0.05). Our study shows that multidisciplinary integrated care may reduce the incidence rate of denosumab-associated severe hypocalcemia among patients with advanced CKD and ESRD.

Management of osteoporosis in patients with chronic kidney disease

Patients with CKD have a 4-fivefold higher rate of fractures. The incidence of fractures increases with deterioration of kidney function. The process of skeletal changes in CKD patients is characterized by compromised bone strength because of deterioration of bone quantity and/or quality. The fractures lead to a deleterious effect on the quality of life and higher mortality in patients with CKD. The pathogenesis of bone loss and fracture is complex and multi-factorial. Renal osteodystrophy, uremic milieu, drugs, and systemic diseases that lead to renal failure all contribute to bone damage in CKD patients. There is no consensus on the optimal diagnostic method of compromised bone assessment in patients with CKD. Bone quantity and mass can be assessed by dual-energy x-ray absorptiometry (DXA) or quantitative computed tomography (QCT). Bone quality on the other side can be assessed by non-invasive methods such as trabecular bone score (TBS), high-resolution bone imaging methods, and invasive bone biopsy. Bone turnover markers can reflect bone remodeling, but some of them are retained by kidneys. Understanding the mechanism of bone loss is pivotal in preventing fracture in patients with CKD. Several non-pharmacological and therapeutic interventions have been reported to improve bone health. Controlling laboratory abnormalities of CKD-MBD is crucial. Anti-resorptive therapies are effective in improving BMD and reducing fracture risk, but there are uncertainties about safety and efficacy especially in advanced CKD patients. Accepting the prevalent of low bone turnover in patients with advanced CKD, the osteo-anabolics are possibly promising. Parathyroidectomy should be considered a last resort for intractable cases of renal hyperparathyroidism. There is a wide unacceptable gap in osteoporosis management in patients with CKD. This article is focusing on the updated management of CKD-MBD and osteoporosis in CKD patients. Chronic kidney disease deteriorates bone quality and quantity. The mechanism of bone loss mainly determines pharmacological treatment. DXA and QCT provide information about bone quantity, but assessing bone quality, by TBS, high-resolution bone imaging, invasive bone biopsy, and bone turnover markers, can guide us about the mechanism of bone loss.

Alkaline Phosphatase: An Old Friend as Treatment Target for Cardiovascular and Mineral Bone Disorders in Chronic Kidney Disease

Alkaline phosphatase (ALP) is an evolutionary conserved enzyme and widely used biomarker in clinical practice. Tissue-nonspecific alkaline phosphatase (TNALP) is one of four human isozymes that are expressed as distinct TNALP isoforms after posttranslational modifications, mainly in bone, liver, and kidney tissues. Beyond the well-known effects on bone mineralization, the bone ALP (BALP) isoforms (B/I, B1, B1x, and B2) are also involved in the pathogenesis of ectopic calcification. This narrative review summarizes the recent clinical investigations and mechanisms that link ALP and BALP to inflammation, metabolic syndrome, vascular calcification, endothelial dysfunction, fibrosis, cardiovascular disease, and mortality. The association between ALP, vitamin K, bone metabolism, and fracture risk in patients with chronic kidney disease (CKD) is also discussed. Recent advances in different pharmacological strategies are highlighted, with the potential to modulate the expression of ALP directly and indirectly in CKD–mineral and bone disorder (CKD-MBD), e.g., epigenetic modulation, phosphate binders, calcimimetics, vitamin D, and other anti-fracture treatments. We conclude that the significant evidence for ALP as a pathogenic factor and risk marker in CKD-MBD supports the inclusion of concrete treatment targets for ALP in clinical guidelines. While a target value below 120 U/L is associated with improved survival, further experimental and clinical research should explore interventional strategies with optimal risk–benefit profiles. The future holds great promise for novel drug therapies modulating ALP.

Effects of bone turnover status on the efficacy and safety of denosumab among haemodialysis patients

Denosumab is reported to increase bone mineral density (BMD) among haemodialysis patients; however, hypocalcaemia is a serious adverse effect among chronic kidney disease (CKD) patients. Identifying which patients will show greater improvement in BMD is important. We enrolled 84 haemodialysis patients with osteoporosis in our study. 28 patients initiated denosumab treatment between October 2019 and October 2020. We assessed BMD changes and investigated the association between baseline bone turnover marker (BTM) levels and 6-month changes in BMD after denosumab treatment. BMD was increased at 6 months in denosumab-treated patients compared with patients not treated with denosumab (lumbar spine: 5.34% vs. - 0.49%; total hip: 2.43% vs. - 0.47%). Bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase-5b (TRACP-5b) at baseline were independently associated with increased BMD in the total hip (BAP: β = 0.472, p value = 0.004; TRACP-5b: β = 0.433, p value = 0.008) and lumbar spine (BAP: β = 0.591, p value = 0.001; TRACP-5b: β = 0.613, p value = 0.0008). BAP and TRACP-5b were also independent predictors of hypocalcaemic events (OR [95% CI] 1.747 [1.084-4.604] and 1.006 [1.000-1.015], respectively). BTMs may be associated with increased BMD and hypocalcaemic events after denosumab treatment. BTM measurement may be useful for assessing the effect of denosumab on BMD; however, careful monitoring of serum calcium levels is needed.

Prevalence and risk factors of osteoporosis in saudi end-stage renal disease patients on hemodialysis

Background:

Objective:

Methods:

Results:

Conclusion:

Diagnosis and management of osteoporosis in chronic kidney disease stages 4 to 5D: a call for a shift from nihilism to pragmatism

The European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) CKD-MBD working group, in collaboration with the Committee of Scientific Advisors of the International Osteoporosis Foundation, published a position paper for the diagnosis and management of osteoporosis in patients with CKD stages 4-5D (eGFR < 30 ml/min 1.73 m²). The present article reports and summarizes the main recommendations included in this 2021 document. The following areas are reviewed: diagnosis of osteoporosis; risk factors for fragility fractures; fracture risk assessment; intervention thresholds for pharmacological intervention; general and pharmacological management of osteoporosis; monitoring of treatment, and systems of care, all in patients with CKD stages 4-5D. Guidance is provided for clinicians caring for CKD stages 4-5D patients with osteoporosis, allowing for a pragmatic individualized diagnostic and therapeutic approach as an alternative to current variations in care and treatment nihilism.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

Bone Quality in Chronic Kidney Disease Patients: Current Concepts and Future Directions - Part II

Background

Patients with chronic kidney disease (CKD) have an increased risk of osteoporotic fractures, which is due not only to low bone volume and mass but also poor microarchitecture and tissue quality. The pharmacological and nonpharmacological interventions detailed, herein, are potential approaches to improve bone health in CKD patients. Various medications build up bone mass but also affect bone tissue quality. Antiresorptive therapies strikingly reduce bone turnover; however, they can impair bone mineralization and negatively affect the ability to repair bone microdamage and cause an increase in bone brittleness. On the other hand, some osteoporosis therapies may cause a redistribution of bone structure that may improve bone strength without noticeable effect on BMD. This may explain why some drugs can affect fracture risk disproportionately to changes in BMD.

Summary

An accurate detection of the underlying bone abnormalities in CKD patients, including bone quantity and quality abnormalities, helps in institution of appropriate management strategies. Here in this part II, we are focusing on advancements in bone therapeutics that are anticipated to improve bone health and decrease mortality in CKD patients.

Key Messages

Therapeutic interventions to improve bone health can potentially advance life span. Emphasis should be given to the impact of various therapeutic interventions on bone quality.

Denosumab in chronic kidney disease: a narrative review of treatment efficacy and safety

People with chronic kidney disease (CKD) are at high risk of bone fractures. In this review, we summarize the complexity of fracture prevention in CKD, describe the usefulness of a medication called denosumab, and review its safety in this population. Our article will help doctors manage brittle bones in CKD and encourage researchers to conduct more studies to improve bone health in CKD.

PURPOSE

Patients with CKD are at increased risk of fragility fractures and associated consequences. We discuss the complexity of fracture prevention in CKD, summarize the efficacy and safety of denosumab, and provide an approach to denosumab-induced hypocalcemia.

METHODS

Using predefined terms, we searched PubMed, MEDLINE, and Google Scholar for studies on fracture prevention in CKD and the efficacy and safety of denosumab. We included observational studies, randomized controlled trials (RCTs), meta-analyses, evidence-based reviews, and clinical practice guidelines.

RESULTS

The diagnosis of osteoporosis and prevention of related fragility fractures is complex in CKD, particularly in those with advanced and end-staged kidney disease (ESKD). Prior to initiating denosumab, it is important to assess for and optimize CKD-mineral and bone disorders (CKD-MBD). In observational studies and small RCTs, denosumab has been shown to improve bone mineral density and reduce bone turnover in CKD, but there have been no studies focused upon its fracture efficacy. Denosumab-induced hypocalcemia has also been reported, which disproportionately impacts those with ESKD. Risk factors for hypocalcemia with denosumab use in CKD include lower baseline serum calcium and 25 hydroxyvitamin D and both low and high bone turnover. Choosing the "right patient" for denosumab, supplementing with calcium and vitamin D, adjusting calcium dialysate, and close clinical monitoring are essential if considering this drug.

CONCLUSION

With optimization of CKD-MBD, calcium and vitamin D supplementation, and close monitoring, denosumab can be considered in CKD. There are however opportunities to better understand its fracture efficacy and safety in an RCT setting.

Differentiating the causes of adynamic bone in advanced chronic kidney disease informs osteoporosis treatment

Patients with chronic kidney disease (CKD) have an increased fracture risk because of impaired bone quality and quantity. Low bone mineral density predicts fracture risk in all CKD stages, including advanced CKD (CKD G4-5D). Pharmacological therapy improves bone mineral density and reduces fracture risk in moderate CKD. Its efficacy in advanced CKD remains to be determined, although pilot studies suggest a positive effect on bone mineral density. Currently, antiresorptive agents are the most commonly prescribed drugs for the prevention and therapy of osteoporosis. Their use in advanced CKD has been limited by the lack of large clinical trials and fear of causing kidney dysfunction and adynamic bone disease. In recent decades, adynamic bone disease has evolved as the most predominant form of renal osteodystrophy, commonly associated with poor outcomes, including premature mortality and progression of vascular calcification. Evolving evidence indicates that reduction of bone turnover by parathyroidectomy or pharmacological therapies, such as calcimimetics and antiresorptive agents, are not associated with premature mortality or accelerated vascular calcification in CKD. In contrast, chronic inflammation, oxidative stress, malnutrition, and diabetes can induce low bone turnover and associate with poor prognosis. Thus, the conditions causing suppression of bone turnover rather than the low bone turnover per se may account for the perceived association with outcomes. Anabolic treatment, in contrast, has been suggested to improve turnover and bone mass in patients with advanced CKD and low bone turnover; however, uncertainty about safety even exceeds that of antiresorptive agents. Here, we critically review the pathophysiological concept of adynamic bone disease and discuss the effect of low bone turnover on the safety and efficacy of anti-osteoporosis pharmacotherapy in advanced CKD.

The Role of Bone Biopsy in the Management of CKD-MBD

A bone biopsy is still considered the gold standard for diagnosis of renal osteodystrophy. It allows to measure both static and dynamic parameters of bone remodeling and is the only method able to evaluate mineralization and allows analysis of both cortical and trabecular bone. Although bone volume can be measured indirectly by dual-energy X-ray absorptiometry, mineralization defects, bone metal deposits, cellular number/activity, and even turnover abnormalities are difficult to determine by techniques other than qualitative bone histomorphometry. In this review, we evaluate the role of bone biopsy in the clinical practice.

European Consensus Statement on the diagnosis and management of osteoporosis in chronic kidney disease stages G4-G5D

Controlling the excessive fracture burden in patients with chronic kidney disease (CKD) Stages G4-G5D remains an impressive challenge. The reasons are 2-fold. First, the pathophysiology of bone fragility in patients with CKD G4-G5D is complex and multifaceted, comprising a mixture of age-related (primary male/postmenopausal), drug-induced and CKD-related bone abnormalities. Second, our current armamentarium of osteoporosis medications has not been developed for, or adequately studied in patients with CKD G4-G5D, partly related to difficulties in diagnosing osteoporosis in this specific setting and fear of complications. Doubts about the optimal diagnostic and therapeutic approach fuel inertia in daily clinical practice. The scope of the present consensus paper is to review and update the assessment and diagnosis of osteoporosis in patients with CKD G4-G5D and to discuss the therapeutic interventions available and the manner in which these can be used to develop management strategies for the prevention of fragility fracture. As such, it aims to stimulate a cohesive approach to the management of osteoporosis in patients with CKD G4-G5D to replace current variations in care and treatment nihilism.

Hypocalcemia and bone mineral changes in hemodialysis patients with low bone mass treated with denosumab: a 2-year observational study

BACKGROUND

Increases in bone mineral density (BMD) following a single dose of denosumab and increased incidence of denosumab-associated acute hypocalcemia (DAAH) have been reported in chronic kidney disease (CKD) patients. Little is known about clinical risk factors related to DAAH and the long-term effect of denosumab on BMD in hemodialysis patients.

METHODS

An observational non-controlled study involving 47 hemodialysis patients was conducted to determine the independent risk factors related to percent changes in serum Ca levels associated with denosumab using multivariate regression analysis. Optimal predictive markers for DAAH were explored by receiver operating characteristic (ROC) analysis. Percent changes of BMD at the lumbar spine (LS) and femoral neck (FN) over 24 months were investigated.

RESULTS

The incidence of DAAH (serum corrected Ca (cCa) ≤ 8 mg/dL) following denosumab was 25.5%. Multivariate regression analysis showed baseline bone alkaline phosphatase (BAP) was independently related to percent changes in cCa levels (β = -0.407, P = 0.008). Tartrate-resistant acid phosphatase (TRACP-5b) was found to be the most accurate marker to predict DAAH with AUC of 0.750 (95% CI; 0.546-0.954, P = 0.02) and the optimal cut-off level was 670 mU/mL with sensitivity; 0.727 and specificity; 0.733. BMD significantly increased by 5.9 ± 1.7% (P = 0.01) at LS and 4.2 ± 1.5% (P = 0.04) at FN at 24 months.

CONCLUSION

In hemodialysis patients, high bone turnover was an independent risk factor for the Ca declines induced by denosumab. Denosumab significantly increased BMD at LS and FN over 24 months.

The safety profile of denosumab in oncology beyond the safety of denosumab as an anti-osteoporotic agent: still more to learn

INTRODUCTION

Initially endorsed as an antiosteoporotic agent, denosumab ‒ human monoclonal antibody inhibiting the receptor activator of nuclear factor kappa-B ligand (RANKL)‒ has currently shown an anticancer potential, rationalizing its exploitation in oncology. A prerequisite for leveraging denosumab in oncology is a favorable safety profile.

AREAS COVERED

The present review provides an overview of the adverse events of denosumab in oncology, with a focus on hypocalcemia, medication-related osteonecrosis of the jaw, atypical femoral fracture(s), post-denosumab vertebral fractures, increased risk of infections, and excess of second primary cancer. Representative studies addressing the safety and efficacy of denosumab compared to bisphosphonates in oncology are summarized. Critical gaps in the literature concerning the safety of denosumab in oncology are highlighted as opposed to plenty of available safety data on denosumab as an antiosteoporotic agent.

EXPERT OPINION

Despite the generally acceptable safety profile of denosumab in oncology, many issues remain unresolved. Further research is mandatory to counteract current challenges, namely: (i) validation of risk factors for adverse events; (ii) elucidation of the pathophysiology of the adverse events in search of actionable molecular pathways; (iii) illumination of the association of denosumab with increased risk of infections and/or second primary cancer; (iv) establishment of optimal diagnostic, and therapeutic protocols.

Changes in bone mineral density after parathyroidectomy in patients with moderate to severe primary hyperparathyroidism

OBJECTIVE

Primary hyperparathyroidism (PHPT) is relatively common in China and results in severe damage to the skeletal system. This study aimed to investigate changes in bone mineral density (BMD) over 2 years in patients with PHPT after parathyroidectomy.

METHODS

This retrospective cohort study included patients with PHPT who underwent parathyroidectomy between January 2010 and December 2015. BMD and T-scores and Z-scores of the lumbar spine (L1, L2, L3, and L4) and total hip (femoral neck, great trochanter, and Ward's triangle) at baseline and 2 years after surgery were measured by dual-energy X-ray absorptiometry.

RESULTS

Thirty patients with moderate to severe PHPT (17 men and 13 women) aged 38.90±15.48 years were included. BMD, and T-score and Z-score values at the lumbar spine and total hip at 6 months, 1 year, and 2 years after parathyroidectomy were significantly improved compared with preoperative values. Improvement in BMD was largest at L4 (46.7%) and smallest at L1 (37.4%) in the lumbar spine 2 years after parathyroidectomy. For the total hip, the increase in BMD was largest at Ward's triangle (42.6%) and smallest at the femoral neck (37.5%).

CONCLUSIONS

BMD of the lumbar spine and total hip is improved after parathyroidectomy in patients with PHPT.

Osteoporosis in Patients with Chronic Kidney Diseases: A Systemic Review

Chronic kidney disease (CKD) is associated with the development of mineral bone disorder (MBD), osteoporosis, and fragility fractures. Among CKD patients, adynamic bone disease or low bone turnover is the most common type of renal osteodystrophy. The consequences of CKD-MBD include increased fracture risk, greater morbidity, and mortality. Thus, the goal is to prevent the occurrences of fractures by means of alleviating CKD-induced MBD and treating subsequent osteoporosis. Changes in mineral and humoral metabolism as well as bone structure develop early in the course of CKD. CKD-MBD includes abnormalities of calcium, phosphorus, PTH, and/or vitamin D; abnormalities in bone turnover, mineralization, volume, linear growth, or strength; and/or vascular or other soft tissue calcification. In patients with CKD-MBD, using either DXA or FRAX to screen fracture risk should be considered. Biomarkers such as bALP and iPTH may assist to assess bone turnover. Before initiating an antiresorptive or anabolic agent to treat osteoporosis in CKD patients, lifestyle modifications, such as exercise, calcium, and vitamin D supplementation, smoking cessation, and avoidance of excessive alcohol intake are important. Managing hyperphosphatemia and SHPT are also crucial. Understanding the complex pathogenesis of CKD-MBD is crucial in improving one’s short- and long-term outcomes. Treatment strategies for CKD-associated osteoporosis should be patient-centered to determine the type of renal osteodystrophy. This review focuses on the mechanism, evaluation and management of patients with CKD-MBD. However, further studies are needed to explore more details regarding the underlying pathophysiology and to assess the safety and efficacy of agents for treating CKD-MBD.

Impact of denosumab on cardiovascular calcification in patients with secondary hyperparathyroidism undergoing dialysis: a pilot study

The receptor activator of nuclear factor-kappa B ligand (RANKL)/RANK/osteoprotegerin system is dysregulated in hyperparathyroid bone diseases. The introduction of denosumab preceding elective surgery as an alternative option when surgery is not possible immediately.

INTRODUCTION

The effects of denosumab on vascular calcification in patients with chronic renal failure and low bone mass have been a subject of interest. Therefore, this investigation aimed to determine the short-term changes in vascular calcification after denosumab treatment using a serial electrocardiography-gated computed tomography (CT) to measure coronary artery calcification (CAC) in patients with secondary hyperparathyroidism (SHPT) and low bone mass.

METHODS

This 6-month study enrolled patients with SHPT and low bone mass (T-score < - 2.5) owing to dialysis. The 2 groups administered denosumab at a dose of 60 mg (denosumab group), and conventional treatment (control group) had 21 patients each. All patients underwent CT scans at baseline and at the follow-up examination at 6 months to determine the bone mineral density and CAC.

RESULTS

The control group demonstrated a significant increase in Agatston scores (187.79 ± 72.27) (P = 0.004). However, no significant change was noted in the denosumab group (P = 0.41). In the denosumab group, only the baseline serum alkaline phosphatase levels correlated negatively with changes in the CAC score (P = 0.01); the baseline alkaline phosphatase levels were the deciding biomarkers for non-responsive CAC scores by Berry Criteria after denosumab treatment (P = 0.02). The denosumab group demonstrated significantly increased bone mineral density in the femoral neck and lumbar spine (P < 0.01).

CONCLUSION

The findings provide evidence that denosumab may suppress the progression of CAC and also regress osseous calcification in severe cases of high bone turnover.

Contrasting PTH Response of Denosumab Use in Dialysis Patients: A Report of 2 Cases

A common complication of end-stage renal disease (ESRD) is mineral and bone disorder. Yet, many anti-osteoporotic drugs are contraindicated in ESRD patients. Denosumab, a monoclonal antibody, does not require renal dose adjustment. However, its use is uncertain due to a lack of safety and efficacy of data in this population. Two hemodialysis patient cases of contrasting responses in parathyroid hormone (PTH) after denosumab administration were observed. Patient 1, a 62-years-old male received denosumab 60 mg at Day 0. His calcium decreased from 8.8 mg/dL to 6.8 mg/dL on Day 30. The PTH level increased from 265 pg/mL to 372 pg/mL after 30 days. Calcium and PTH levels approached normal range after increasing doses of vitamin D/calcium supplements, and calcitriol. Patient 2, a 72-years-old male on hemodialysis also received denosumab 60 mg on Day 0. His baseline calcium and PTH were 9.2 mg/dL and 420 pg/mL, respectively. On Day 30, his calcium level decreased (6.8 mg/dL) but, PTH level drastically increased (>5000 pg/mL). Denosumab commonly causes hypocalcemia and hyperparathyroidism since it inhibits osteoclast activation, reduces calcium release from bone and increases PTH levels as a compensatory mechanism. With a wait-and-watch approach, Patient 2’s levels approached the normal range (calcium 9.6 mg/dL and PTH 274 pg/mL at Day 90).

Denosumab-induced hypocalcemia in patients with osteoporosis: can you know who will get low?

Hypocalcemia was reported at low rates (0.05-1.7%) in denosumab-treated postmenopausal women with osteoporosis. This real-life study shows a 7.4% rate of denosumab-induced hypocalcemia in community-dwelling osteoporotic men and women. Pretreatment serum calcium and creatinine levels are major predictors for this complication. Serum-calcium monitoring may help to identify and prevent severe hypocalcemia.

PURPOSE

RCTs have reported a 0.05-1.7% rate of hypocalcemia in denosumab-treated postmenopausal women with osteoporosis, but long-term real-life data are lacking. We assessed the rate of hypocalcemia in osteoporotic community-dwelling patients treated with denosumab.

METHODS

A retrospective analysis was conducted based on medical records (2010-2018) from a large HMO. An albumin-adjusted serum calcium concentration lower than 8.5 mg/dL was defined as hypocalcemia.

RESULTS

We included 2005 patients (93% women, mean age 76 ± 9 years). Hypocalcemia developed during treatment in 149 patients (7.4%; 1% less than 8 mg/dL): in 66 after 0.5-1 years; 48 after 1-2 years; 35 after > 2 years. On comparison of the hypocalcemic and normocalcemic patients, the strongest predictors of hypocalcemia were pretreatment levels of albumin-adjusted serum calcium (9.1 ± 0.4 vs. 9.4 ± 0.5 mg/dL, respectively; p < 0.05) and creatinine (0.9 ± 0.5 vs. 0.8 ± 0.3 mg/dL, respectively; p < 0.05). The hypocalcemia rate increased in parallel to a decrease in eGFR (p = 0.032 for the difference between eGFR ranges). Baseline calcium level ≤ 9.31 mg/dL predicted hypocalcemia with a sensitivity of 77% and specificity of 56%. A model of (- 2)*calcium + creatinine predicted hypocalcemia (3.7% when lower and 17.1% when higher than - 17.4). Gender, age, 25-hydroxyvitamin-D, parathyroid hormone, alkaline phosphatase, and whether denosumab was given as first or advanced line of osteoporotic therapy had no predictive value.

CONCLUSION

Real-life rates of denosumab-induced hypocalcemia are higher than previously reported. Hypocalcemia might develop after each dose of denosumab in ongoing treatment. Adequate calcium and vitamin D supplementation are needed. Serum calcium monitoring is advised in high-risk patients for early detection of severe hypocalcemia.

Use of denosumab to treat refractory hypercalcemia in a peritoneal dialysis patient with immobilization and tertiary hyperparathyroidism

Hypercalcemia due to excess parathyroid hormone (PTH) production is a common condition among patients with end-stage renal disease (ESRD), often referred to as tertiary hyperparathyroidism. There are limited effective medical treatment options currently available for such patients. Denosumab is a monoclonal antibody that inhibits osteoclast activation, thereby reducing calcium release from bones. Denosumab has been used to treat medically-refractory hypercalcemia in non-ESRD patients with hyperparathyroidism. Denosumab has also been used to treat non-PTH-mediated hypercalcemia in patients with advanced chronic kidney disease and ESRD. In this case report, we describe the use of denosumab to successfully treat a case of medically refractory hypercalcemia due to immobilization in a patient on peritoneal dialysis with severe underlying tertiary hyperparathyroidism. In spite of persistently elevated PTH, hypercalcemia quickly resolved after a single dose of denosumab. The patient subsequently developed temporary hypocalcemia requiring medical intervention. Our case report, which is the first described use of denosumab for treatment of hypercalcemia in the setting of tertiary hyperparathyroidism in a peritoneal dialysis patient, adds to the body of literature suggesting denosumab is a useful therapeutic agent in patients with ESRD. Issues with post-treatment electrolyte management and other therapeutic considerations are also discussed.

Off-label uses of denosumab in metabolic bone diseases

Denosumab (Dmab), a monoclonal antibody against the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) which substantially suppresses osteoclast activity, has been approved for the treatment of common metabolic bone diseases, including postmenopausal osteoporosis, male osteoporosis, and glucocorticoid-induced osteoporosis, in which the pathway of the RANK/RANKL/osteoprotegerin is dysregulated. However, the imbalance of RANKL/RANK/osteoprotegerin is also implicated in the pathogenesis of several other rare metabolic bone diseases, including Juvenile Paget disease, fibrous dysplasia, Hajdu Cheney syndrome and Langerhans cell histiocytosis, thus rendering Dmab a potential treatment option for these diseases. Dmab has been also administered off-label in selected patients (e.g., with Paget's disease, osteogenesis imperfecta, aneurysmal bone cysts) due to contraindications or unresponsiveness to standard treatment, such as bisphosphonates. Moreover, Dmab was administered to improve hypercalcemia induced by various diseases, including primary hyperparathyroidism, tuberculosis and immobilization. The aim of this review is to summarize existing evidence on off-label uses of Dmab in metabolic bone diseases and provide opinion for or against its use, which should be always considered on an individual basis.

Evaluation of the association of Wnt signaling with coronary artery calcification in patients on dialysis with severe secondary hyperparathyroidism

BACKGROUND

Patients with end-stage renal disease have a higher risk of death from cardiovascular events, which can be mainly attributed to coronary artery calcification (CAC). Wnt signaling is involved in vascular development and may play a role in vascular calcification. This study aimed to evaluate CAC prevalence in patients on dialysis with severe secondary hyperparathyroidism (SHPT) and identify CAC risk factors.

METHODS

The study is a retrospective analysis of the severe hyperparathyroidism registration study that prospectively recruited patients on dialysis with severe SHPT who were candidates for parathyroidectomy, from October 2013 to May 2015. CAC and bone mineral density (BMD) were measured. Demographic and clinical data including calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone, Dickkopf-related protein 1 (DKK1), and sclerostin levels were analyzed. CAC scores were reported in Agatston units (AU).

RESULTS

A total of 61 patients were included in this study. No CAC, mild CAC (<100 AU), moderate CAC (>100 AU), and severe CAC (>400 AU) were observed in 4.9%, 11.4%, 14.8%, and 68.9% of patients, respectively. DKK1 and sclerostin were not associated with CAC. In univariate analysis, CAC was significantly correlated with age, sex (male), total cholesterol, and intravenous pulse calcitriol (p<0.05). CAC was not inversely correlated with the BMD, T scores, or Z scores of the femoral neck (p>0.05). In multivariate analysis, the stepwise forward multiple linear regression revealed that CAC was associated with age, male sex and intravenous pulse calcitriol (p<0.05). Furthermore, serum sclerostin was positively correlated with the BMD of the femoral neck but negatively associated with intact parathyroid hormone (p<0.05). Serum sclerostin was significantly associated with severely low bone mass with Z-scores<-2.5 of the femoral neck, even when adjusted for serum intact parathyroid hormone, vitamin D status, dialysis pattern, sex, and DKK-1 (p<0.05).

CONCLUSIONS

The patients on dialysis with severe SHPT have a high prevalence of vascular calcification. Although the Wnt signaling pathway could play a role in hyperparathyroid bone disease, CAC may be mainly due to the treatment modality rather than the Wnt signaling pathway associated bone metabolism in patients on dialysis with severe SHPT.

The relative influence of serum ionized calcium and 25-hydroxyvitamin D in regulating PTH secretion in healthy subjects

BACKGROUND

While the inverse relationship between serum ionized calcium (Ca²⁺) and PTH is well-established, the relationship between 25(OH)D and PTH showed conflicting results. The study aimed to evaluate the relative contributions of age, sex, serum Ca²⁺, ionized magnesium (Mg²⁺), 25(OH)D and 1,25(OH)₂D in regulating PTH secretion in healthy subjects.

METHODS

This is a secondary analysis of an observational study performed from March 2014 to July 2015 carried out in 2259 blood donors (1652 men and 607 women, age range 18-68 years). Subjects with parathyroid disorders and taking drugs that affect mineral metabolism were excluded.

RESULTS

Significant correlations [between Ca²⁺ and PTH (r = -0.223, p < 0.001), 25(OH)D and PTH (r = -0.178, p < 0.001) and between PTH and age (r = 0.322, p < 0.001)] were found. As a preliminary step to multivariate analysis, a regression tree analysis was performed using PTH as response variable and age, Ca²⁺, Mg²⁺, 25(OH)D, 1,25(OH)₂D and sex as explanatory variables to determine the effect of each covariate on the response variable. For subjects <38 years, 25(OH)D was the most important parameter in regulating PTH. For subjects ≥38 both 25(OH)D and Ca²⁺ levels regulated PTH secretion. Subjects with 25(OH)D < 13 ng/mL had average higher PTH; in this group only, subjects with Ca²⁺ ≥ 1.30 mmol/L had average lower PTH compared to subjects with Ca²⁺ < 1.30. The multivariate analysis showed that all variables had a significant effect (p < 0.001) on PTH. Anova Type III errors c indicated that 25(OH)D accounted for 32.1% of the total variance in PTH, Ca²⁺ accounted for 18% of the total variance, BMI for 14.3%, and 1,25(OH)₂D for 11.1%. The remaining percentage was attributable to age and sex. This was confirmed by the regression tree approach, where 25(OH)D and Ca²⁺ accounted for the largest variation in the average levels of PTH.

DISCUSSION

Under stable conditions 25(OH)D plays a significant role in regulating PTH secretion. Under conditions of relative vitamin D sufficiency, Ca²⁺ also plays an important role.

Effects of Denosumab and Alendronate on Bone Health and Vascular Function in Hemodialysis Patients: A Randomized, Controlled Trial

Mineral and bone disorders including osteoporosis are common in dialysis patients and contribute to increased morbimortality. However, whether denosumab and alendronate are effective and safe treatments in hemodialysis patients is not known. Thus, we conducted a prospective, three-center study of 48 hemodialysis patients who were diagnosed as having osteoporosis and had not received anti-osteoporotic agents previously. Participants were randomized to either denosumab or intravenous alendronate, and all subjects received elemental calcium and calcitriol during the initial 2 weeks. The primary endpoint was the percent change in lumbar spine bone mineral density (LSBMD) at 12 months of treatment. The secondary endpoints included the following: change in BMD at other sites; change of serum bone turnover markers (BTM), coronary artery calcium score (CACS), ankle-brachial pressure index (ABI), brachial-ankle pulse wave velocity (baPWV), flow mediated dilation (FMD), and intima-media thickness at the carotid artery (CA-IMT); change from day 0 to day 14 in serum levels of Ca and P; time course of serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (i-PTH); new fractures; and adverse events. Initial supplementation with elemental calcium and calcitriol markedly ameliorated the decrease of serum corrected calcium (cCa) levels induced by denosumab during the first 2 weeks, whereas serum cCa levels in the alendronate group were increased. Denosumab and alendronate markedly decreased serum levels of BTM and increased LSBMD at 12 months compared with baseline. However, no significant differences were found in the changes in LSBMD between the two groups. The serum cCa, P, and i-PTH levels in the two groups were maintained within the appropriate range. In contrast to the anti-osteoporotic effects, no significant differences after 12 months of treatment were found in the CACS, CA-IMT, ABI, baPWV, and FMD compared with pretreatment in both groups. Denosumab and alendronate treatment improved LSBMD, reduced BTM, and appeared to be safe in hemodialysis patients with osteoporosis. © 2019 American Society for Bone and Mineral Research.

Effects of denosumab on bone metabolism and bone mineral density in kidney transplant patients: a systematic review and meta-analysis

OBJECTIVE

The use of immunosuppressive agents, especially glucocorticoids, are associated with increased risks of bone loss in kidney transplant patients. Denosumab, a potent antiresorptive agent, has been shown to increase bone mineral density (BMD) in patients with CKD. However, its effects on bone metabolism and BMD in kidney transplant patients remain unclear.

METHODS

A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through April 2018 to identify studies evaluating denosumab's effect on changes in bone metabolism and BMD from baseline to post-treatment course in kidney transplant patients. Study results were pooled and analyzed utilizing random-effects model. The protocol for this systematic review is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42018095055).

RESULTS

Five studies (a clinical trial and four cohort studies) with a total of 162 kidney transplant patients were identified. The majority of patients had a baseline eGFR ≥ 30 mL/min/1.73 m². After treatment (≥ 6 to 12 months), there were significant increases in BMD with standardized mean differences (SMDs) of 3.26 (95% CI 0.88-5.64) and 1.83 (95% CI 0.43 to 3.22) for lumbar spine and femoral neck, respectively. There were also significant increases in T scores with SMDs of 0.92 (95% CI 0.58 to 1.25) and 1.14 (95% CI 0.17 to 2.10) for lumbar spine and femoral neck, respectively. After treatment, there were no significant changes in serum calcium (Ca) or parathyroid hormone (PTH) from baseline to post-treatment course (≥ 6 months) with mean differences (MDs) of 0.52 (95% CI, - 0.13 to 1.16) mmol/L and - 13.24 (95% CI, - 43.85 to 17.37) ng/L, respectively. The clinical trial data demonstrated more asymptomatic hypocalcemia in the denosumab (12 episodes in 39 patients) than in the control (1 episode in 42 patients) group. From the cohort studies, the pooled incidence of hypocalcemia following denosumab treatment was 1.7% (95% CI 0.4 to 6.6%). All reported hypocalcemic episodes were mild and asymptomatic, but the majority of patients required Ca and vitamin D supplements.

CONCLUSION

Among kidney transplant patients with good allograft function, denosumab effectively increases BMD and T scores in the lumbar spine and femur neck. From baseline to post-treatment, there are no differences in serum Ca and PTH. However, mild hypocalcemia can occur following denosumab treatment, requiring monitoring and titration of Ca and vitamin D supplements.

Severe hypophosphatemia induced by denosumab in a patient with osteomalacia and tenofovir disoproxil fumarate-related acquired Fanconi syndrome

Denosumab, a novel agent that inhibits osteoclasts, reduces the risk of fracture in patients with osteoporosis. However, worsening of hypophosphatemia and other symptoms may be induced by denosumab in patients with pre-existing hypophosphatemic osteomalacia. A 58-year-old man with hepatitis B presented with diffuse bone pain and muscle weakness. Denosumab was prescribed by the orthopedist according to documented low bone mass and spine compression fracture. After administering denosumab, the patient's bone pain worsened, and he later developed a right tibia stress fracture. His condition was diagnosed as adult-onset hypophosphatemic osteomalacia complicated by multiple bone fractures, which resulted from Fanconi syndrome with proximal tubulopathy due to tenofovir disoproxil fumarate (TDF) treatment for his hepatitis B. Denosumab use leads to aggressive hypophosphatemic osteomalacia and the complication of stress fractures, because of its effects on bone resorption. Physicians should be aware that in patients with chronic hepatitis B monoinfection who are administered TDF therapy, bone pain or fracture is possible but preventable by timely monitoring of serum phosphate levels. Denosumab should not be used in patients with untreated osteomalacia or vitamin D deficiency, as it may lead not only to hypocalcemia but also to hypophosphatemia in these patients.

Denosumab-Induced Severe Hypocalcaemia in Chronic Kidney Disease

Background

Hypocalcaemia is increasingly recognized as a complication of denosumab use in Chronic Kidney Disease (CKD) patients with osteoporosis. Despite Therapeutic Goods Administration (TGA) notifications in 2013, we have subsequently encountered several cases of denosumab-induced hypocalcaemia, raising concern about lack of widespread awareness among prescribing practitioners.

Aims

We reviewed the morbidity and healthcare intervention needs of CKD patients with hypocalcaemia attributed to denosumab.

Methods

A retrospective case series of CKD patients with clinically significant hypocalcaemia after exposure to denosumab, encountered at the tertiary care referral hospital from December 2013 to February 2017, was undertaken.

Results

Eight patients (52-85 years of age) with stage 4-5 CKD developed clinically significant hypocalcaemia (corrected calcium 1.45±0.21mmol/L) following denosumab therapy for osteoporosis. Seven of the eight patients required inpatient management with three patients requiring intravenous calcium replacement and cardiac monitoring in a high dependency unit. Our study also identified additional factors that could potentially contribute to hypocalcaemia such as lack of calcium supplementation, use of noncalcium based phosphate binders, absence of or use of lower doses of calcitriol supplementation, low vitamin D levels, concomitant treatment with loop diuretics, history of parathyroidectomy, or presence of acute medical illness.

Conclusion

Multiple cases of severe hypocalcaemia in CKD patients following denosumab exposure were encountered after TGA warnings, resulting in considerable morbidity and intensive healthcare interventions in CKD patients. We advocate greater awareness amongst the medical profession, careful consideration before using denosumab in CKD patients, and close follow-up after administration to prevent morbidity.

Updates in CKD-Associated Osteoporosis

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with bone loss and fractures. The purpose of this review is to provide clinicians with an overview of the underlying pathogenesis of CKD-associated osteoporosis, and a summary of the current diagnostic and therapeutic approaches to this disease.

RECENT FINDINGS

In 2017, the Kidney Disease Improving Global Outcomes Committee on Bone Quality updated their guidelines to include screening for osteoporosis and fracture risk by dual energy X-ray absorptiometry in patients with CKD. Once a diagnosis of osteoporosis and/or fracture risk is established, it is not clear how nephrologists should manage their patients. Patients with CKD should be screened for CKD-associated osteoporosis and considered for strategies that prevent bone loss and fractures. Assessment of bone turnover via imaging, biochemical testing, or bone biopsy can help guide the choice of therapy. Randomized controlled trials are needed to assess safety and efficacy of treatments to prevent bone loss and fractures.

Rethinking Bone Disease in Kidney Disease

Renal osteodystrophy (ROD) is the bone component of chronic kidney disease mineral and bone disorder (CKD-MBD). ROD affects bone quality and strength through the numerous hormonal and metabolic disturbances that occur in patients with kidney disease. Collectively these disorders in bone quality increase fracture risk in CKD patients compared with the general population. Fractures are a serious complication of kidney disease and are associated with higher morbidity and mortality compared with the general population. Furthermore, at a population level, fractures are at historically high levels in patients with end-stage kidney disease (ESKD), whereas in contrast the general population has experienced a steady decline in fracture incidence rates. Based on these findings, it is clear that a paradigm shift is needed in our approach to diagnosing and managing ROD. In clinical practice, our ability to diagnose ROD and initiate antifracture treatments is impeded by the lack of accurate noninvasive methods that identify ROD type. The past decade has seen advances in the noninvasive measurement of bone quality and strength that have been studied in kidney disease patients. Below we review the current literature pertaining to the epidemiology, pathology, diagnosis, and management of ROD. We aim to highlight the pressing need for a greater awareness of this condition and the need for the implementation of strategies that prevent fractures in kidney disease patients. Research is needed for more accurate noninvasive assessment of ROD type, clinical studies of existing osteoporosis therapies in patients across the spectrum of kidney disease, and the development of CKD-specific treatments. © 2018 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Hypocalcemia and bone mineral density changes following denosumab treatment in end-stage renal disease patients: a meta-analysis of observational studies

The incidence of hypocalcemia and bone mineral density (BMD) changes in end-stage renal disease (ESRD) patients on denosumab remains unclear. We performed this meta-analysis to assess the incidence of denosumab-associated hypocalcemia and effects of denosumab on BMD in ESRD patients. A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through November 2017 to identify studies evaluating incidence of denosumab-associated hypocalcemia and changes in serum calcium, phosphate, alkaline phosphatase (ALP), parathyroid hormone (PTH), and BMD from baseline to post-treatment course of denosumab in ESRD patients. Study results were pooled and analyzed using a random-effect model. The protocol for this meta-analysis is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017081074). Six observational studies with a total of 84 ESRD patients were enrolled. The pooled estimated incidence of hypocalcemia during denosumab treatment was 42% (95% CI 29-55%, I² = 0%). Hypocalcemia occurred approximately 7 to 20 days after the first dose and reached nadir of low calcium levels in the first 2 weeks up to 2 months. However, there were no significant changes in serum calcium or phosphate from baseline to post-treatment course (≥ 3 months after treatment) with mean differences [MDs] of 0.20 mg/dL (95% CI, - 0.30 to 0.69 mg/dL) and - 0.10 mg/dL (95% CI, - 0.70 to 0.49 mg/dL). There were significant reductions in ALP and PTH levels with standardized mean differences (SMDs) of - 0.65 (95% CI - 1.13 to - 0.16) and - 1.89 (95% CI - 3.44 to - 0.34), respectively. There were significant increases in T-scores with MDs of 0.39 (95% CI 0.10 to 0.69) and 0.79 (95% CI 0.60 to 0.98) for lumbar spine and femoral neck, respectively. Our study demonstrates the estimated incidence of denosumab-associated hypocalcemia in dialysis patients of 42%. From baseline to post-treatment course, although there are no differences in serum calcium and phosphate, our findings suggest significant reductions in ALP and PTH and a significant increase in BMD. Currently, denosumab should not be considered as the treatment of choice in ESRD patients until more safety and efficacy data are available.

THERAPY OF ENDOCRINE DISEASE: Denosumab vs bisphosphonates for the treatment of postmenopausal osteoporosis

The most widely used medications for the treatment of osteoporosis are currently bisphosphonates (BPs) and denosumab (Dmab). Both are antiresorptives, thus targeting the osteoclast and inhibiting bone resorption. Dmab achieves greater suppression of bone turnover and greater increases of bone mineral density (BMD) at all skeletal sites, both in naïve and pretreated patients. No superiority on fracture risk reduction has been documented so far. In long-term administration, BPs reach a plateau in BMD response after 2-3 years, especially at the hip, while BMD increases progressively for as long as Dmab is administered. Both BPs and Dmab are generally considered safe, although they have been correlated to rare adverse events, such as osteonecrosis of the jaw and atypical femoral fractures. Dmab should be preferred in patients with impaired renal function. BPs are embedded in the bone, from which they are slowly released during bone remodeling, therefore continuing to act for years after their discontinuation. In contrast, Dmab discontinuation fully and rapidly reverses its effects on bone markers and BMD and increases the risk for fractures; therefore, Dmab discontinuation should be discouraged, especially in previously treatment-naïve patients, regardless of the conventional fracture risk. In case of discontinuation, other treatment, mainly BPs, should immediately follow, although the optimal sequential treatment strategy is yet to be defined. Combination of teriparatide with Dmab or zoledronic acid, but not alendronate, provides increased BMD gains at all sites. In conclusion, both BPs and Dmab are safe and efficient therapeutic options although their particularities should be carefully considered in an individual basis.

Management of Osteoporosis in CKD

CKD mineral and bone disease is a common complication of kidney disease, and it affects the majority of patients with moderate to severe CKD. Recently, prospective studies have shown that measurement of bone mineral density by dual energy x-ray absorptiometry predicts incident fracture, providing nephrologists the ability to risk classify patients for skeletal fragility and targeted antifracture strategies for the first time. Furthermore, an expanding body of literature and anecdotal evidence suggest that pharmacologic agents used to treat osteoporosis in the general population can be safely used in patients with CKD. This review highlights the effects of the Kidney Disease Improving Global Outcomes updates on the management of CKD-associated osteoporosis, discusses recent investigations on the effects of antiosteoporotic agents in patients with CKD, and provides an overview of novel antiosteoporosis agents and the potential challenges related to their use in CKD.

Bone disease in primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a disease of high bone turnover, decreased bone mineral density (BMD) especially at cortical sites, and increased risk of fractures at all skeletal sites. Early diagnosis during the last decades resulted in milder forms of bone involvement. New methods of imaging and validation such as high resolution peripheral quantitative computed tomography and trabecular bone score provide evidence of disturbed bone microarchitecture and explain further the increased risk of fractures at both cortical and trabecular skeletal sites. Parathyroidectomy has a long-term beneficial effect on the skeleton and is probably prudent to refer PHPT patients for surgery in all cases where increased bone fragility is suspected. Bisphosphonates (BPs), mainly alendronate, have been proved as reasonable choices for BMD improvement while cinacalcet has no effect on bone strength in PHPT. Combination of BPs and cinacalcet, is a valid therapeutic approach from a pathophysiological point of view at least in terms of bone health, however, an adequately powered study to prove it is lacking. Adequate dietary calcium intake and vitamin D supplementation is advised as in the general population for the skeletal integrity of PHPT patients albeit with a close monitoring of serum and urinary calcium levels.

Denosumab for Male Hemodialysis Patients with Low Bone Mineral Density: A Case-Control Study

Denosumab increases bone mineral density (BMD) in patients not receiving hemodialysis therapy. However, limited data are available in the literature concerning the use of denosumab in hemodialysis patients. We treated male hemodialysis patients with low radius BMD with denosumab therapy for 1 year and evaluated its effect on radius BMD. Seventeen patients were treated with denosumab 60 mg every 6 months, and 20 patients were not treated with denosumab (control group). At seven days, the mean corrected calcium level decreased from 9.2 ± 0.5 mg to 8.5 ± 0.5 mg (P < 0.01), and mean serum phosphorus decreased from 5.0 ± 1.3 mg/dl to 4.2 ± 0.9 mg/dl (P < 0.01). At 1 month, the corrected calcium and serum phosphorus levels were 9.2 ± 0.9 mg/dl and 4.0 ± 1.1 mg/dl, respectively. At 1 year, BMD increased by 2.6%  ± 4.4% in the denosumab group and decreased by 4.5%  ± 7.7% in the control group (P < 0.001). In our observational study, denosumab therapy represents an effective treatment for male dialysis patients with low BMD.

Positioning novel biologicals in CKD-mineral and bone disorders

Renal osteodystrophy (ROD), the histologic bone lesions of chronic kidney disease (CKD), is now included in a wider syndrome with laboratory abnormalities of mineral metabolism and extra-skeletal calcifications or CKD-mineral and bone disorders (CKD-MBD), to highlight the increased burden of mortality. Aging people, frequently identified as early CKD, could suffer from either the classical age-related osteoporosis (OP) or ROD. Distinguishing between these two bone diseases may not be easy without bone biopsy. In any case, besides classical therapies for ROD, nephrologists are now challenged by the possibility of using new drugs developed for OP. Importantly, while therapies for ROD mostly aim at controlling parathyroid secretion with bone effects regarded as indirect, new drugs for OP directly modulate bone cells activity. Thus, their action could be useful in specific types of ROD. Parathyroid hormone therapy, which is anabolic in OP, could be useful in renal patients with low turnover bone disease. Denosumab, the monoclonal antibody against receptor activator of NF-κB ligand (RANK-L) that inhibits osteoclast activity and proliferation, could be beneficial in cases with high turnover bone. Use of romosozumab, the monoclonal antibody against sclerostin, which both stimulates osteoblasts and inhibits osteoclasts, could allow both anabolic and anti-resorptive effects. However, we should not forget the systemic role now attributed to CKD-MBD. In fact, therapies targeting bone cells activity could also result in unpredicted extra-bone effects and affect cardiovascular outcomes. In conclusion, the new biologicals established for OP could be useful in renal patients with either OP or ROD. In addition, their potential non-bone effects warrant investigation.

Combination Therapy of Denosumab and Calcitriol for a Renal Transplant Recipient with Severe Bone Loss due to Therapy-Resistant Hyperparathyroidism

Denosumab (DMAb), a complete human type monoclonal antibody directed against the receptor activator of nuclear factor-κB ligand, has gained attention as a novel treatment for osteoporosis. However, its efficacy in patients with chronic kidney disease (CKD) remains unclear. We describe a 64-year-old man with severe bone loss and persistent secondary hyperparathyroidism (SHPT) after renal transplantation, whose condition failed to respond to conventional pharmacologic or surgical interventions. He underwent parathyroidectomy with left forearm autograft of crushed tiny parathyroid gland (PTG) particles. However, the autografted PTGs became swollen and caused persistent SHPT in spite of two additional parathyroidectomies of the left forearm. A single subcutaneous administration of DMAb induced hypocalcemia, which was corrected by calcium supplementation and high-dose calcitriol. Eventually, combination therapy with DMAb and calcitriol led to a decline in the patient's elevated serum parathyroid hormone levels, normalization of laboratory markers of bone metabolism, and improvement in bone mineral density in a short period of time. To the best of our knowledge, this is the first case report of severe bone loss with persistent SHPT in a renal transplant recipient effectively treated with the combination therapy of DMAb and vitamin D (VD). Although DMAb itself exerts no direct effects on PTGs, the DMAb treatment improved the patient's bone loss. In addition, administration of DMAb allowed for high-dose VD therapy which ultimately controlled SHPT and prevented DMAb-induced hypocalcemia. Therefore, this combination therapy might be a reasonable therapeutic strategy to reverse severe bone loss due to therapy-resistant SHPT in patients with CKD.

Does the OPG/RANKL system contribute to the bone-vascular axis in chronic kidney disease? A systematic review

Vascular calcification (VC) is highly prevalent in patients with chronic kidney disease (CKD) and is strongly associated with cardiovascular mortality and morbidity. Accumulating evidence over the past decade has challenged the hypothesis of close interaction between bone and VC what raises the possibility of a common underlying pathophysiological mechanism. Lately, bone regulatory proteins such as: osteoprotegerin (OPG) and Receptor Activator for Nuclear Factor κB Ligand (RANKL) has attracted attention of researchers as a possible key mediators of bone-vascular calcification imbalance. The literature search was carried out using the MEDLINE/PubMed database and a combination of keywords and MeSH terms, and only papers published since January 2005 to July 2016 were selected. The search resulted in 562 potential articles. After selection according to the eligibility criteria, 107 studies fulfilled were included (102 full texts and 5 was case reports). OPG and RANKL plays essential role in the regulation of bone metabolism and may be regarded as a possible link between VC, bone and mineral metabolism in CKD patients. Further studies are required to determine the diagnostic significance of these proteins in evaluation of progression and severity of VC process in CKD patients. Finally, the efficacy and safety, especially in regard to VC, of anti-RANKL therapy in CKD patients requires well-designed prospective, randomized trials.

Chronic kidney disease and fragility fracture

Osteoporosis is defined simply as "a skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. Thus, any bone lesion that causes fragility fracture is osteoporosis, which has quite heterogeneous backgrounds. Chronic kidney disease-related bone and mineral disease (CKD-MBD) is defined as "a systemic disorder of mineral and bone metabolism due to CKD, which is manifested by abnormalities in bone and mineral metabolism and/or extra-skeletal calcification". Although CKD-MBD is one of the possible causes of osteoporosis, we do not have evidences that CKD-MBD is the only or crucial determinant of bone mechanical strength in CKD patients. The risk of hip fracture is considerably high in CKD patients. Drugs that intervene in systemic mineral metabolism, indeed, lead to the improvement on bone histology in CKD patients. However, it remains unclear whether the intervention in systemic mineral metabolism also improves bone strength, today. Thus, the use of drugs that directly act on bone and the introduction of fracture liaison concept are promising strategies for fragility fracture prevention among CKD patients, as well as treatment for CKD-MBD.

The Strategy to Prevent and Regress the Vascular Calcification in Dialysis Patients

The high prevalence of arterial calcification in end-stage renal disease (ESRD) is far beyond the explanation by common cardiovascular risk factors such as aging, diabetes, hypertension, and dyslipidemia. The finding relies on the fact that vascular and valvular calcifications are predictors of cardiovascular diseases and mortality in persons with chronic renal failure. In addition to traditional cardiovascular risk factors such as diabetes mellitus and blood pressure control, other ESRD-related risks such as phosphate retention, excess calcium, and prolonged dialysis time also contribute to the development of vascular calcification. The strategies are to reverse "calcium paradox" and lower vascular calcification by decreasing procalcific factors including minimization of inflammation (through adequate dialysis and by avoiding malnutrition, intravenous labile iron, and positive calcium and phosphate balance), correction of high and low bone turnover, and restoration of anticalcification factor balance such as correction of vitamin D and K deficiency; parathyroid intervention is reserved for severe hyperparathyroidism. The role of bone antiresorption therapy such as bisphosphonates and denosumab in vascular calcification in high-bone-turnover disease remains unclear. The limited data on sodium thiosulfate are promising. However, if calcification is to be targeted, ensure that bone health is not compromised by the treatments.