Secondary hyperparathyroidism: pathogenesis, disease progression, and therapeutic options

Bridging adults and paediatrics with secondary hyperparathyroidism receiving haemodialysis: a pharmacokinetic-pharmacodynamic analysis of cinacalcet

AIMS

The aims of this study were to develop a pharmacokinetic (PK) and PK-pharmacodynamic (PK/PD) model of cinacalcet in adults and paediatrics with secondary hyperparathyroidism (SHPT) on dialysis, to test covariates of interest, and to perform simulations to inform dosing in paediatrics with SHPT.

METHODS

Cinacalcet PK, intact parathyroid hormone (iPTH) and corrected calcium (cCa) time courses following multiple daily oral doses (1-300 mg) were modelled using a nonlinear mixed effects modelling approach using data from eight clinical studies. Model-based trial simulations, using adult or paediatric titration schemas, predicted efficacy (iPTH change from baseline and proportion achieving iPTH decrease ≥30%) and safety (cCa change from baseline and proportion achieving cCa ≤8.4 mg/dL) endpoints at 24 weeks.

RESULTS

Cinacalcet PK parameters were described by a two-compartment linear model with delayed first-order absorption-elimination (apparent clearance = 287.74 L h-1 ). Simulations suggested that paediatric starting doses (1, 2.5, 5, 10 and 15 mg) would provide PK exposures less than or similar to a 30 mg adult dose. The titrated dose simulations suggested that the mean (prediction interval) proportion of paediatric and adult subjects achieving ≥30% reduction in iPTH from baseline at Week 24 was 49% (36%, 62%), and 70.1% (62.5%, 77%), respectively. Additionally, the mean (confidence interval) proportion of paediatric and adult subjects achieving cCa ≤8.4 mg dL-1 at Week 24 was 8% (2%, 18%) and 23.6% (17.5%, 30.5%), respectively.

CONCLUSIONS

Model-based simulations showed that the paediatric cinacalcet starting dose (0.2 mg kg-1 ), titrated to effect, would provide the desired PD efficacy (PTH suppression <30%) while minimizing safety concerns (hypocalcaemia).

Predictors of cinacalcet discontinuation and reinitiation in hemodialysis patients: results from 7 European countries

Background

The putative benefits of cinacalcet therapy for management of secondary hyperparathyroidism (SHPT) are thought to be most manifested when patients are taking it consistently and as prescribed. Real-world descriptions of cinacalcet prescription discontinuation and reinitiation in European hemodialysis patients are lacking. To address this knowledge gap, we used Dialysis Outcomes and Practice Patterns Study (DOPPS) data, based on dialysis facility medical records, from seven European countries to estimate rates and predictors of cinacalcet prescription discontinuation and reinitiation in hemodialysis patients and to describe the trajectories of CKD-MBD laboratory values after discontinuation.

Methods

Cox regression analyses were used to predict (1) cinacalcet discontinuation among 613 patients with ≥3 consecutive months without cinacalcet prescription immediately prior to a new cinacalcet prescription and (2) cinacalcet reinitiation among 415 patients with a newly discontinued cinacalcet prescription immediately after ≥3 consecutive months of prescribed use.

Results

Cinacalcet was discontinued in 21 and 35% of new users after 6 and 12 months, respectively. Cinacalcet was reinitiated in 38 and 49% of newly-discontinued users after 6 and 12 months, respectively. Predictors of discontinuation included lower parathyroid hormone (PTH) in the previous month (< 150 pg/ml vs. 150–299, HR = 2.57 [95% CI: 1.52–4.33]) and lower serum calcium in the previous month (< 8.4 mg/dl vs. 8.4–10.19, HR = 1.67 [95% CI: 1.08–2.59]). Predictors of reinitiation included higher PTH in the previous month (300–599 pg/ml vs. 150–299, HR = 1.88 [95% CI = 1.19–2.97]; 600+ pg/ml, HR = 3.02 [95% CI = 1.92–4.76]). After cinacalcet discontinuation, mean serum PTH increased from 408 to 510 pg/ml, mean serum calcium briefly rose from 9.12 to 9.22 mg/dl before declining to 9.06 mg/dl, and mean serum phosphorus showed little change.

Conclusions

Nephrologist discontinuation of cinacalcet therapy is common in European countries. Additional research is needed to identify optimal cinacalcet treatment strategies for SHPT management, including comparisons of intermittent cinacalcet therapy versus sustained treatment with reduced dose or frequency.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1355-5) contains supplementary material, which is available to authorized users.

Association of novel biomarkers with major clinical outcomes in a cohort of patients with atherosclerotic renovascular disease

Introduction

In this study, we investigate whether the addition of biomarkers to a model based on traditional risk factors improves risk prediction and patient selection for revascularization in atherosclerotic renovascular disease.

Methods

Patients in the Salford Renovascular Study who had the following biomarkers analysed on a baseline sample were included in this study: FGF-23, Cystatin C, kidney injury molecule-1, myeloperoxidase, neutrophil gelatinase-associated lipocalin, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), high-sensitivity Troponin T and anti-apolipoprotein A1 IgG. Cox proportional hazards models and net reclassification index were used to study the effects of either individual or a panel of biomarkers on predicting death, end-stage kidney disease and cardiovascular events.

Results

A total of 112 patients were followed up for a median 59.9 months (IQR 33.6–86.9). In total, 75 patients died, 21 reached end-stage kidney disease and 36 suffered a cardiovascular event. Only NT-proBNP maintained a statistically significant association with all end-points (death: HR 1.62 [95% CI 1.26–2.10], P < 0.0005; end-stage kidney disease: HR 1.51 [95% 1.19–1.91], P = 0.001; cardiovascular event: HR 1.56 [95% CI 1.23–1.97], P < 0.0005). Risk reclassification improved with addition of all biomarkers as a panel to the base model. Only patients with NT-proBNP concentrations above 300 ng/L gained benefit from revascularization with regard to all adverse end-points compared with medically managed patients.

Conclusions

NT-proBNP is independently associated with increased risk for all adverse events in atherosclerotic renovascular disease. Novel biomarkers may have an incremental risk predictive value when used in combination with traditional risk factors, and NT-proBNP may have value in patient selection for revascularization. Given the small size of this study, larger multicentre studies are required to validate these findings.

Long-Term Efficacy and Safety of Evocalcet in Japanese Patients with Secondary Hyperparathyroidism Receiving Hemodialysis

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD), and as the disease progresses SHPT is associated with systemic consequences, termed CKD-mineral and bone disorder. Currently, cinacalcet is indicated for the treatment of SHPT; however, cinacalcet is associated with upper gastrointestinal adverse events. Evocalcet has been developed to address these issues, but the long-term safety and efficacy of evocalcet need to be evaluated. To more accurately reflect clinical practice, this phase 3, multicenter, open-label study was specifically designed without a cinacalcet washout period, and focused on those patients who switched from cinacalcet to evocalcet. A total of 137 SHPT patients undergoing hemodialysis were enrolled, of whom 113 switched from cinacalcet to evocalcet. The most frequent type of adverse drug reaction was decreased adjusted calcium. The incidence of gastrointestinal-related adverse events did not increase in a dose-dependent manner as the dose of evocalcet was increased. The percentage of patients achieving the target intact parathyroid hormone concentration increased from 40.9% to 72.3% with 52-week treatment. The corrected serum calcium and phosphorus levels remained largely unchanged throughout the study. The long-term safety and efficacy of evocalcet was confirmed using a clinically relevant intra-subject dose-adjustment strategy in SHPT patients undergoing hemodialysis.

Role of Parathyroid Hormone Assay and Bedside Ultrasound in the Emergency Department in Differentiating Acute Kidney Injury from Chronic Kidney Disease: A Systematic Review

Introduction

It is not uncommon for patients without preceding history of kidney disease to present to the Emergency department with renal failure. The absence of prior medical records or renal imaging presents a diagnostic challenge. Elevated parathyroid hormone levels or echogenic contracted kidneys on ultrasound are known to point to a diagnosis of chronic kidney disease. The literature in this regard is surprisingly limited. The objective of this study is to assess the role of intact parathyroid (iPTH) blood level and bedside ultrasound in differentiating acute kidney injury from chronic kidney disease.

Methods

A systematic review which included a literature search of 3 databases, PubMed, Embase, and Cinahl (R) as also secondary sources, was done. The inclusion criteria evaluated studies which evaluated iPTH or bedside ultrasound in differentiating acute kidney injury from chronic kidney disease. We excluded studies which used other laboratory biomarkers like neutrophil gelatin associated lipocalin (NGAL) or carbamylated haemoglobin. A total of 2256 articles were identified. After screening, the relevant articles were reviewed, and an assessment of their methodological quality was made based on the CASP: Critical Appraisals Skill Programme.

Results

Of the 2256 articles identified, after screening, only 5 were identified as relevant.

Conclusions

An elevated parathyroid hormone level and echogenic contracted kidneys on bedside ultrasound in the Emergency department can help differentiate acute kidney injury from chronic kidney disease. This differentiation helps decide need for admission as well as further management. Although iPTH level may also rise in acute kidney injury, the value (2.5 times normal) can discriminate it from chronic kidney disease.

The effect of parathyroidectomy on patients' symptoms in tertiary hyperparathyroidism

BACKGROUND

The efficacy of parathyroidectomy for primary and secondary hyperparathyroidism is well-established but evidence in tertiary hyperparathyroidism is lacking. We examined parathyroidectomy's effect in tertiary hyperparathyroidism.

METHODS

Patients with tertiary hyperparathyroidism who underwent parathyroidectomy were followed up for 12 months. A modification of the 13-item parathyroid symptoms list developed by Pasieka was administered at 0, 1, 3, 6, and 12 months post-surgery. We also examined if preoperative factors would predict symptom improvement post-surgery.

RESULTS

Ninety-one patients were included. Survey response rates at 1, 3, 6, and 12 months post-surgery were 97.8%, 90.1%, 82.4%, and 80.2%, respectively. Mean preoperative Pasieka parathyroid score (PSS) was 6.3 ± 2.7. At first month, PSS decreased to 2.9 ± 2.0 (P < .001) and was sustained at 3, 6, and 12 months (2.7 ± 2.1, P < .001, 2.3 ± 1.6, P < .001 and 3.4 ± 2.5, P < .001). The degree of PSS reduction at 1-month post-parathyroidectomy correlated strongly with preoperative symptom severity (Pearson's coefficient: 0.690, P < .001).

CONCLUSIONS

Parathyroid symptoms unequivocally improve post-parathyroidectomy. The greatest degree of improvement was observed in early postoperative period up to 6 months.

Pathogenesis and treatment of electrolyte problems post transplant

PURPOSE OF REVIEW

Electrolyte abnormalities posttransplant are common occurrences that can have significant short-term and long-term effects on graft outcome and patient quality of life. Understanding the pathophysiology of these electrolyte derangements can help guide management to optimize bone health and minimize cardiovascular disease. This review explores the pathogenesis of the most common postrenal transplant electrolytes abnormalities as well as current treatment options.

RECENT FINDINGS

Clarifications of the role of FGF-23 has improved our understanding of posttransplant bone disease in addition to the known roles of hyperparathyroidism and vitamin D. The mechanisms of renal electrolyte wasting by immunosuppressive agents give insight into potential treatment options for hyperkalemia and hypomagnesemia.

SUMMARY

Understanding the pathogenesis of the common electrolyte abnormalities found post renal transplant may lead to targeted treatment options that in turn may improve transplant complications. Further studies are required to evaluate the effects on long-term outcomes of renal allografts.

FGF23, Biomarker or Target?

Fibroblast growth factor 23 (FGF23) plays a key role in the complex network between the bones and other organs. Initially, it was thought that FGF23 exclusively regulated phosphate and vitamin D metabolism; however, recent research has demonstrated that an excess of FGF23 has other effects that may be detrimental in some cases. The understanding of the signaling pathways through which FGF23 acts in different organs is crucial to develop strategies aiming to prevent the negative effects associated with high FGF23 levels. FGF23 has been described to have effects on the heart, promoting left ventricular hypertrophy (LVH); the liver, leading to production of inflammatory cytokines; the bones, inhibiting mineralization; and the bone marrow, by reducing the production of erythropoietin (EPO). The identification of FGF23 receptors will play a remarkable role in future research since its selective blockade might reduce the adverse effects of FGF23. Patients with chronic kidney disease (CKD) have very high levels of FGF23 and may be the population suffering from the most adverse FGF23-related effects. The general population, as well as kidney transplant recipients, may also be affected by high FGF23. Whether the association between FGF23 and clinical events is causal or casual remains controversial. The hypothesis that FGF23 could be considered a therapeutic target is gaining relevance and may become a promising field of investigation in the future.

An integrated analysis of safety and tolerability of etelcalcetide in patients receiving hemodialysis with secondary hyperparathyroidism

Background

Calcimimetics have been shown to be effective and safe therapies for the treatment of secondary hyperparathyroidism (sHPT), a serious complication of disordered mineral metabolism associated with dialysis-dependent chronic kidney disease. Etelcalcetide, a recently approved intravenous calcimimetic, reduces serum parathyroid hormone (PTH), calcium, phosphorus, and fibroblast growth factor-23 concentrations. Here we report the first integrated safety profile of etelcalcetide using pooled data from five pivotal clinical trials.

Methods

This analysis included data from patients receiving hemodialysis with moderate to severe sHPT enrolled in two randomized, placebo-controlled trials; a randomized active-controlled (with cinacalcet) trial; and two single-arm, open-label extension trials. Patients initially received etelcalcetide intravenously 5 mg three times weekly (TIW) after hemodialysis; with potential dose increases of 2.5 or 5 mg at 4-week intervals to a maximum dose of 15 mg TIW, depending on serum PTH and calcium levels. The nature, frequency, and severity of treatment-emergent adverse events (AEs) and changes in laboratory parameters were assessed.

Results

Overall, we evaluated 1023 patients from the placebo-controlled trials, 683 from the active-controlled trial, and 1299 from open-label extensions. The frequency and nature of common treatment-emergent AEs reported for the etelcalcetide arm were consistent among the placebo-controlled and active-controlled trials. The most common AEs were those related to mineral metabolism (decreased blood calcium, hypophosphatemia, muscle spasms) or gastrointestinal abnormalities (diarrhea, nausea, vomiting). Hypocalcemia leading to discontinuation of either calcimimetic was experienced in ≤ 1% of patients.

Conclusions

This integrated safety assessment of etelcalcetide across placebo- and active-controlled trials showed an overall favorable risk/benefit profile, with safety similar to that of cinacalcet. Consistent with its mechanism of action, the most important risks associated with etelcalcetide were serum calcium reductions and hypocalcemia-related AEs; no new safety findings were identified in the pooled long-term extension trials.

Calcium-Phosphate Metabolism Disorders in Patients with Renal Failure Clinical Significance, Diagnosis and Treatment

Chronic kidney diseases (CKD) are commonly associated with calcium and phosphorus metabolism disorders. The general term of “renal osteodystrophy” (ROD) encompasses a complex spectrum of abnormalities in bone and mineral metabolism in CKD. This is one of the most serious and debilitating complications of CKD. It is related to disproportionately high direct and indirect costs of healthcare, thus posing a major burden on society. The development of ROD begins too early in the course of CKD. Some mechanisms involved in the pathogenesis of ROD are reduced calciferol production, calcium deficiency and hyperphosphatemia. Clinically, ROD occurs with varied manifestations – osteomalacia, osteoporosis, adynamic bone disease. The diagnosis and the treatment are a challenge for the physician and effort should be made to prolong the duration and quality of life of the affected patients.

A randomized, double-blind, placebo-controlled study to assess the efficacy and safety of cinacalcet in pediatric patients with chronic kidney disease and secondary hyperparathyroidism receiving dialysis

BACKGROUND

This randomized phase 3 study evaluated the efficacy and safety of cinacalcet in children with secondary hyperparathyroidism (SHPT) receiving dialysis.

METHODS

This study had double-blind and open-label phases. Eligible patients aged 6-< 18 years were randomized to cinacalcet (starting dose ≤ 0.20 mg/kg) or placebo. The primary endpoint was ≥ 30% reduction from baseline in mean intact parathyroid hormone (iPTH). Secondary endpoints included mean iPTH ≤ 300 pg/mL; percentage change from baseline in corrected total serum calcium, phosphorus, and calcium phosphorus product (Ca × P); and safety.

RESULTS

The double-blind phase comprised 43 patients (cinacalcet, n = 22; placebo, n = 21). Nineteen months into the study, regulatory authorities were notified of a fatality; the study was subsequently terminated after a 14-month clinical hold. Before the hold, 12 patients (55%) on cinacalcet and four (19%) on placebo achieved the primary endpoint (p = 0.017), and 27% and 24%, respectively, achieved iPTH ≤ 300 pg/mL. The between-group differences (95% CI) in percentage changes for total serum calcium, phosphorus, and Ca × P were - 4% (- 9 to 1%), - 6% (- 21 to 8%), and - 10% (- 23 to 3%). The mean maximum actual weight-adjusted daily cinacalcet dosage administered was 0.99 mg/kg/day. Overall, 82% of patients on cinacalcet and 86% on placebo had ≥ 1 treatment-emergent adverse event; the most common were vomiting (32%, 24%, respectively), hypocalcemia (23%, 19%), nausea (18%, 14%), and hypertension (14%, 24%).

CONCLUSIONS

Despite early termination, efficacy and safety outcomes observed with cinacalcet in children with SHPT on dialysis were consistent with adult observations, suggesting cinacalcet may meet an unmet medical need for this population.

Microwave ablation vs. parathyroidectomy for secondary hyperparathyroidism in maintenance hemodialysis patients

INTRODUCTION

Secondary hyperparathyroidism (SHPT) is a serious and common problem in patients undergoing maintenance hemodialysis. Minimally invasive microwave ablation (MWA) has been used to treat SHPT and shows some advantages. However, its efficacy is still undefined. The primary purpose of this study was to determine the efficacy and safety of MWA compared to total parathyroidectomy plus forearm autotransplantation.

METHODS

The SHPT patients who were undergoing maintenance hemodialysis (follow-up for 6 to 24 months after treatments) were divided into a MWA group (n = 33) and a parathyroidectomy group (n = 48). The efficacy (serum intact parathyroid hormone [iPTH], calcium, and phosphorus levels) and safety (hoarseness, hypocalcaemia, and persistently low iPTH) were compared between the two groups. Additionally, the study explored potential predictors of response to MWA by a logistic regression analysis.

FINDINGS

There were no significant differences in baseline characteristics between the two groups. The rates of achieving the recommended goal for iPTH were significantly higher in the MWA group than that in the parathyroidectomy group at all follow-up times: 57.58% vs. 12.50% at one-day (P < 0.001), 45.45% vs. 16.67% at 1-week (P = 0.005), 57.58% vs. 16.67% at 2-week (P < 0.001), 57.58% vs. 22.92% at 1-month (P = 0.002), and 69.70% vs. 35.42% at 3-month (P = 0.002), 76.47% vs. 28.57% at 6-month (P = 0.005), 87.50% vs. 47.37% at 12-month (P = 0.008), and 81.82% vs. 52.63% at 24-month (P = 0.015), respectively. However, there were no significant differences for phosphorus or calcium at any of the follow-up times (P > 0.05). The persistently low iPTH was more in the parathyroidectomy group (64.6%) than that in the MWA group (0%) (P < 0.001), but there was no significant difference in hoarseness or hypocalcaemia (P > 0.05). Baseline levels of iPTH (P = 0.021) and patient age (P = 0.011) were determined as predictors by univariate logistic regression analysis.

CONCLUSION

The MWA could be an alternative to parathyroidectomy for SHPT but its eventual superiority has to be demonstrated by a proper study.

Parathyroidectomy versus cinacalcet for tertiary hyperparathyroidism; a retrospective analysis

Introduction

Tertiary hyperparathyroidism (tHPT), i.e., persistent HPT after kidney transplantation, affects 17–50% of transplant recipients. Treatment of tHPT is mandatory since persistently elevated PTH concentrations after KTx increase the risk of renal allograft dysfunction and osteoporosis. The introduction of cinacalcet in 2004 seemed to offer a medical treatment alternative to parathyroidectomy (PTx). However, the optimal management of tHPT remains unclear.

Methods

A retrospective analysis was performed on patients receiving a kidney transplantation (KT) in two academic centers in the Netherlands. Thirty patients undergoing PTx within 3 years of transplantation and 64 patients treated with cinacalcet 1 year after transplantation for tHPT were included. Primary outcomes were serum calcium and PTH concentrations 1 year after KT and after PTx.

Results

Serum calcium normalized in both the cinacalcet and the PTx patients. PTH concentrations remained above the upper limit of normal (median 22.0 pmol/L) 1 year after KT, but returned to within the normal range in the PTx group (median 3.7 pmol/L). Side effects of cinacalcet were difficult to assess; minor complications occurred in three patients. Re-exploration due to persistent tHPT was performed in three (10%) patients.

Conclusion

In patients with tHPT, cinacalcet normalizes serum calcium, but does not lead to a normalization of serum PTH concentrations. In contrast, PTx leads to a normalization of both serum calcium and PTH concentrations. These findings suggest that PTx is the treatment of choice for tHPT.

Uremic lion face syndrome

Mineral bone disorder is a common feature of chronic kidney disease. Lion face syndrome is rare complication of severe hyperparathyroidism in end-stage renal disease patients, which has been less commonly reported due to dialysis and medical treatment advances in the last decade. The early recognition of the characteristic facial deformity is crucial to prompt management and prevent severe disfigurement. The authors present a rare case of severe hyperparathyroidism presenting with lion face syndrome and bone fractures.

Parathyroidectomy in dialysis patients: Indications, methods, and consequences

Secondary hyperparathyroidism, characterized by increased PTH synthesis and secretion, is often seen in advanced stages of chronic kidney disease. Excessive proliferation of parathyroid cells leads to the development of diffuse hyperplasia that subsequently progresses to nodular histology. Refractory hyperparathyroidism occurs when parathyroid glands fail to respond to medical therapy. Parathyroidectomy (PTX), surgical resection of parathyroid glands, is usually performed in cases of persistent serum levels of PTH above 1000 pg/mL associated with hypercalcemia or when hyperparathyroidism is refractory to conservative therapy. Parathyroidectomy can be carried out using different procedures: subtotal PTX or total PTX with or without parathyroid autotransplantation. Parathyroid surgery may have undesirable consequences due to PTH oversuppression, such as the development of adynamic bone disease; hungry bone syndrome is quite common after this surgery. However, PTX improves survival and parameters of mineral metabolism. Parathyroidectomy needs to be considered in those patients with severe hyperparathyroidism with a poor response to pharmacological treatment and with distinct undesirable effects of PTH on bone and mineral metabolism parameters.

Mineral bone disorders in chronic kidney disease

As the GFR loss aggravates, the disturbed mineral metabolism worsens the bone microstructure and remodelling - scenario, which is known as CKD-mineral bone disease (MBD). CKD-MBD is characterized by : (i) abnormal metabolism of calcium, phosphorus, parathyroid hormone (PTH), or vitamin D; (ii) abnormalities in bone turnover, mineralization, volume linear growth or strength; (iii) soft-tissue calcifications, either vascular or extra-osseous. Uremic vascular calcification and osteoporosis are the most common complications related to CKD-MBD. Disregulated bone turnover by uremic toxin or secondary hyperparathyroidism disturbed bone mineralization and makes it difficult for calcium and inorganic phosphate to enter into bone, resulting in increased serum calcium and inorganic phosphate. Vascular calcification worsens by hyperphosphatemia and systemic inflammation. Since vitamin D deficiency plays an important role in renal osteodystrophy, supplement of nutritional vitamin D is important in treating uremic osteoporosis and vascular calcification at the same time. Its pleotropic effect improves the bone remodeling initiated by osteoblast and alleviates the risk factors for vascular calcification with less hypercalcemia than vitamin D receptor analogs. Therefore, nutritional vitamin D should be considered in managing CKDMBD.

[Pharmacological and clinical profiles of a novel calcimimetic, evocalcet (ORKEDIA®)]

Calcimimetics allosterically activate the calcium receptor (CaR) and inhibit the secretion of parathyroid hormone (PTH). Cinacalcet hydrochloride (cinacalcet) has been approved as the first calcimimetic drug for the treatment of secondary hyperparathyroidism (SHPT) in patients with hemodialysis. Cinacalcet improved the achievement of target serum PTH and Ca levels and helped drastically reduce the number of parathyroidectomies. However, cinacalcet has side effects involving the gastrointestinal tract, such as nausea and vomiting, which makes it difficult to increase the dose and may result in reduced compliance. Evocalcet has been developed to improve defects of cinacalcet for management of SHPT. Evocalcet acts as an allosteric modulator of CaR, just like cinacalcet. However, its metabolic pathway is different from that of cinacalcet. The metabolism of evocalcet by cytochrome P450 is very low, so evocalcet has higher bioavailability. As a result, its pharmacologically effective dose for the inhibition of PTH secretion is lower than that of cinacalcet. Evocalcet had less of an effect on the gastrointestinal tract than cinacalcet because of the reduced dose required. In a clinical trial with a randomized, double-blind, head-to-head comparison study, it was also confirmed that the incidence of gastrointestinal-related adverse events was lower in the evocalcet group than in the cinacalcet group. Evocalcet may thus be a potent option for the management of SHPT.

An open-label, single-dose study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of cinacalcet in pediatric subjects aged 28 days to < 6 years with chronic kidney disease receiving dialysis

BACKGROUND

Calcimimetics, shown to control biochemical parameters of secondary hyperparathyroidism (SHPT), have well-established safety and pharmacokinetic profiles in adult end-stage renal disease subjects treated with dialysis; however, such studies are limited in pediatric subjects.

METHODS

In this study, the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of cinacalcet were evaluated in children with chronic kidney disease (CKD) and SHPT receiving dialysis. Twelve subjects received a single dose of cinacalcet (0.25 mg/kg) orally or by nasogastric or gastric tube. Subjects were randomized to one of two parathyroid hormone (PTH) and serum calcium sampling sequences: [(1) 2, 8, 48 h; or (2) 2, 12, 48 h] and assessed for 72 h after dosing.

RESULTS

Median plasma cinacalcet t_max was 1 h (range 0.5-4.0 h); mean (SD) C_max and AUC_last were 2.83 (1.98) ng/mL and 11.8 (8.74) h*ng/mL, respectively; mean (SD) half-life (t_1/2) was 3.70 (2.57) h. Dose adjustments, based upon body weight (mg/kg), minimized the effects of age, body weight, body surface area, and body mass index on cinacalcet PK. Reductions in serum PTH levels from baseline were observed at 2 to 8 h post-dose (median 10.8 and 29.6%, respectively), returned towards baseline by 12-72 h and were inversely related to changes in the plasma cinacalcet PK profile. Single-dose cinacalcet was well-tolerated with no unexpected safety findings and a PK/PD, safety profile similar to adults.

CONCLUSIONS

In conclusion, a single 0.25 mg/kg dose of cinacalcet was evaluated to be a safe starting dose in these children aged < 6 years.

Pharmacokinetics, Pharmacodynamics, and Safety of the Novel Calcimimetic Agent Evocalcet in Healthy Japanese Subjects: First-in-Human Phase I Study

Background and Objectives

Evocalcet is a novel calcimimetic agent with potential to improve the treatment of secondary hyperparathyroidism in patients with chronic kidney disease. This study aimed to determine the pharmacokinetics, pharmacodynamics, and safety of evocalcet in healthy Japanese subjects.

Methods

This was a single-blind, placebo-controlled, single-dose study and an 8-day multiple-dose study of evocalcet (MT-4580/KHK7580) in 66 healthy Japanese subjects.

Results

After a single dose of evocalcet 1–20 mg, the time to maximum plasma concentration was attained in 1.5–2 h (median), and the elimination half-life was 12.98–19.77 h (mean). Within this dose range, the maximum plasma concentration and area under plasma concentration-time curve increased dose proportionally, confirming linearity. The trough plasma concentrations were relatively unchanged after multiple administration of evocalcet 6 and 12 mg. Evocalcet decreased intact parathyroid hormone and corrected calcium and phosphorus levels in a dose-proportional manner. Regarding its safety, no upper gastrointestinal adverse event occurred after the single and multiple administration of evocalcet at doses up to 12 mg. Tetany was detected in 1 subject (17%) after multiple administration of evocalcet 12 mg. In healthy subjects, the tolerability and safety of evocalcet were observed for a single dose of evocalcet at doses up to 20 mg, and for multiple doses up to 12 mg.

Conclusions

These results suggest that evocalcet may have a comparable efficacy and better safety profile than that of cinacalcet, one of the current treatments for secondary hyperparathyroidism in patients with chronic kidney disease.

Electronic supplementary material

The online version of this article (10.1007/s40261-018-0687-4) contains supplementary material, which is available to authorized users.

The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases

The Ca2+-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca2+ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca2+ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.

Gut microbiota and inflammation in chronic kidney disease and their roles in the development of cardiovascular disease

The health and proper functioning of the cardiovascular and renal systems largely depend on crosstalk in the gut-kidney-heart/vessel triangle. Recent evidence suggests that the gut microbiota has an integral function in this crosstalk. Mounting evidence indicates that the development of chronic kidney and cardiovascular diseases follows chronic inflammatory processes that are affected by the gut microbiota via various immune, metabolic, endocrine, and neurologic pathways. Additionally, deterioration of the function of the cardiovascular and renal systems has been reported to disrupt the original gut microbiota composition, further contributing to the advancement of chronic cardiovascular and renal diseases. Considering the interaction between the gut microbiota and the renal and cardiovascular systems, we can infer that interventions for the gut microbiota through diet and possibly some medications can prevent/stop the vicious cycle between the gut microbiota and the cardiovascular/renal systems, leading to a decrease in chronic cardiovascular and renal diseases.

Effects of the Intravenous Calcimimetic Etelcalcetide on Bone Turnover and Serum Fibroblast Growth Factor 23: Post Hoc Analysis of an Open-label Study

PURPOSE

Secondary hyperparathyroidism (SHPT) is a serious complication that increases the risk of bone disorders in patients with chronic kidney disease (CKD) undergoing hemodialysis. Etelcalcetide is the first injectable calcimimetic approved for treatment of SHPT, which reduces bone turnover markers and suppresses intact fibroblast growth factor 23 (iFGF-23). This study aimed to explore the associations between etelcalcetide-induced changes in circulating factors and serum iFGF-23 levels.

METHODS

This study was a post hoc analysis of data from a previous multicenter, open-label study of etelcalcetide administered to 191 Japanese patients with SHPT undergoing hemodialysis for 52 weeks. Correlations were analyzed between changes from baseline in serum iFGF-23 and serum intact parathyroid hormone (iPTH), corrected calcium, phosphate, bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase-5b (TRACP-5b), and 1α,25-dihydroxyvitamin D (1,25[OH]₂D) levels at 1, 2, 3, 6, and 12 months. Akaike's Information Criterion (AIC) was calculated using serum iPTH, corrected calcium, phosphate, BAP, TRACP-5b, and 1,25(OH)₂D levels as potential predictor variables at each time point. Four models with the smallest AIC at the 3-month time point were chosen as the fitted models to predict changes in iFGF-23 levels, and stepwise multivariate analysis was performed to determine the predictor variables with the greatest contribution to the change in iFGF-23 levels by calculating the partial coefficients of determination.

FINDINGS

The etelcalcetide-induced reduction in iFGF-23 was positively correlated with serum levels of corrected calcium and phosphate and negatively with BAP. By calculating the AIC, corrected calcium, phosphate, iPTH, BAP, and TRACP-5b were suggested to be predictors of iFGF-23 levels. Stepwise multivariate analysis found that phosphate, corrected calcium, BAP, and TRACP-5b correlated with iFGF-23, in order from strongest to weakest.

IMPLICATIONS

These results suggest that etelcalcetide effectively lowered iFGF-23 and that this reduction may occur via improvements in phosphate, corrected calcium, BAP, and TRACP-5b. Etelcalcetide is thus a promising calcimimetic for decreasing iFGF-23 and improving bone turnover in patients with CKD undergoing hemodialysis with severe SHPT, in addition to decreasing PTH itself. JapicCTI identifier: 142,665.

Control of metabolic predisposition to cardiovascular complications of chronic kidney disease by effervescent calcium magnesium citrate: a feasibility study

Aims

Cardiovascular (CV) complications are common in chronic kidney disease (CKD). Numerous metabolic disturbances including hyperphosphatemia, high circulating calciprotein particles (CPP), hyperparathyroidism, metabolic acidosis, and magnesium deficiency are associated with, and likely pathogenic for CV complications in CKD. The goal of this feasibility study was to determine whether effervescent calcium magnesium citrate (EffCaMgCit) ameliorates the aforementioned pathogenic intermediates.

Methods

Nine patients with Stage 3 and nine patients with Stage 5D CKD underwent a randomized crossover study, where they took EffCaMgCit three times daily for 7 days in one phase, and a conventional phosphorus binder calcium acetate (CaAc) three times daily for 7 days in the other phase. Two-hour postprandial blood samples were obtained on the day before and on the 7th day of treatment.

Results

In Stage 5D CKD, EffCaMgCit significantly increased T50 (half time for conversion of primary to secondary CPP) from baseline by 63% (P = 0.013), coincident with statistically non-significant declines in serum phosphorus by 25% and in saturation of octacalcium phosphate by 35%; CaAc did not change T50. In Stage 3 CKD, neither EffCaMgCit nor CaAc altered T50. With EffCaMgCit, a significant increase in plasma citrate was accompanied by statistically non-significant increase in serum Mg and phosphate. CaAc was without effect in any of these parameters in Stage 3 CKD. In both Stages 3 and 5D, both drugs significantly reduced serum parathyroid hormone. Only EffCaMgCit significantly increased serum bicarbonate by 3 mM (P = 0.015) in Stage 5D.

Conclusions

In Stage 5D, EffCaMgCit inhibited formation of CPP, suppressed PTH, and conferred magnesium and alkali loads. These effects were unique, since they were not observed with CaAc. In Stage 3 CKD, neither of the regimens have any effect. These metabolic changes suggest that EffCaMgCit might be useful in protecting against cardiovascular complications of CKD by ameliorating pathobiologic intermediates.

Correlation of Parathyroid Hormone Levels with Mineral Status in End-stage Renal Disease Patients

Parathyroid hormone (PTH) is the main regulator of calcium, phosphate, magnesium, sodium, and potassium homeostasis. Therefore, this study was conducted to evaluate the relationship between PTH and aforementioned minerals in end-stage renal disease (ESRD) patients.

AIM

The aim of this study was to estimate serum intact parathormone (iPTH) and other biochemical parameters in ESRD patients and to find correlation between serum iPTH and biochemical parameters in the study group.

RESULTS

This cross-sectional study included 60 clinically diagnosed patients of ESRD of age (>18 years), either sex. Disordered mineral metabolism is common complications of ESRD patients. The mean value of calcium, phosphorus, and magnesium was 7.90 ± 1.16 mg/dL, 6.44 ± 1.72 mg/dL, and 2.57 ± 0.62 mg/dL, respectively, indicating hypocalcemia, hyperphosphatemia, and hypermagnesemia in ESRD patients. To compensate the deranged mineral status, increased levels of PTH were seen in ESRD patients with mean value of 173.93 ± 62.62 pg/mL. There was a statistically significant positive correlation found between PTH and S. creatinine (P ≤ 0.001; r = 0.596), whereas the statistically significant negative correlation found between PTH and eGFR (P ≤ 0.001; r = -0.525). A significant positive correlation found between PTH and phosphorous (P = 0.003; r = 0.378) and potassium (P ≤ 0.001; r = 0.421). On the other hand, significant negative correlation found with calcium (P ≤ 0.001; r = -0.805) and corrected calcium (P = <0.001; r = -0.769). But nonsignificant association was found with magnesium, sodium, and calcium × phosphorous (P > 0.05).

CONCLUSION

It was concluded that PTH is playing crucial role in mineral metabolism; it should be frequently assessed in order to prevent any untoward mineral decompensation and to prevent complications like bone disease and extra skeletal calcification, and decrease cardiac disease risk in ESRD patients.

Etelcalcetide for Treating Secondary Hyperparathyroidism: An Evidence Review Group Evaluation of a NICE Single Technology Appraisal

The manufacturer of the calcimimetic drug etelcalcetide was invited to make an evidence submission as part of the National Institute for Health and Care Excellence (NICE) Single Technology Appraisal (STA) programme. Within this submission, they reported evidence on the clinical and cost effectiveness of etelcalcetide for the treatment of secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD) on haemodialysis. The Southampton Health Technology Assessments Centre (SHTAC), part of the Wessex Institute at the University of Southampton, was the independent Evidence Review Group (ERG) commissioned to appraise the company's submission. This article describes the ERG's review and critique of the company's submission and summarises the NICE Appraisal Committee's subsequent guidance (issued in June 2017). The clinical-effectiveness evidence submitted by the company consisted of two double-blind, randomised controlled trials (RCTs) comparing etelcalcetide with placebo, one RCT comparing etelcalcetide with cinacalcet, two single-arm extension studies of the above trials, and one single-arm study evaluating the effect of switching from cinacalcet to etelcalcetide. No study specifically examined the population specified in the NICE appraisal scope: patients refractory to standard therapy with phosphate binders and vitamin D (PBVD). None of these trials were designed to collect long-term efficacy data for outcomes such as mortality, bone fractures, cardiovascular events, or parathyroidectomies. Instead, biomarker data from the trials were mapped to long-term outcomes by an assumed linear relationship between the trial outcome, reduction of parathyroid hormone (PTH) by > 30%, and the log-hazard ratios for the occurrence of clinical events derived from a large, long-term RCT of cinacalcet (the EVOLVE trial). After submission of a confidential Patient Access Scheme (PAS) discount reducing etelcalcetide drug costs, the incremental cost-effectiveness ratio (ICER) for etelcalcetide versus cinacalcet was £14,778 per quality-adjusted life-year (QALY) gained in the company's base case. While this value is lower than the NICE threshold range of £20,000 and £30,000 per QALY gained, it was the opinion of the ERG that the ICER was highly uncertain due to efficacy data limitations for etelcalcetide, inadequate synthesis of clinical-effectiveness evidence, and strong assumptions connecting short-term biomarker data with long-term clinical outcomes. The ERG produced an alternative base case for etelcalcetide versus cinacalcet, with an ICER of £22,400 per QALY gained, also subject to uncertainty. The NICE Appraisal Committee recommended etelcalcetide as an option for the treatment of SHPT in adults with CKD only if treatment with a calcimimetic is indicated and cinacalcet is not suitable, subject to the company's provision of the agreed PAS discount.

Phase 2b study of evocalcet (KHK7580), a novel calcimimetic, in Japanese patients with secondary hyperparathyroidism undergoing hemodialysis: A randomized, double-blind, placebo-controlled, dose-finding study

Background

Evocalcet has been developed as a new calcimimetic agent for hemodialysis (HD) patients with secondary hyperparathyroidism (HDSHPT), eliciting fewer gastrointestinal symptoms and drug interactions. We evaluated the efficacy, safety, and optimal starting dose of evocalcet in HDSHPT.

Methods

In this 3-week, Phase 2b, randomized, double-blind, placebo-controlled, multicenter, parallel-group, dose-finding study, Japanese HDSHPT with intact parathyroid hormone (iPTH) ≥240 pg/mL and serum calcium level corrected for albumin ≥8.4 mg/dL were randomized to evocalcet 0.5, 1, 2 mg/day administered orally or placebo under double-blind conditions, and cinacalcet 25 mg/day (open-label conditions).

Results

In total, 152 HDSHPT were randomized. The mean ± standard deviation (median, interquartile range) of percent changes in iPTH from baseline to end of treatment were −8.40±25.43% (−12.16, 39.60), −10.56±22.86% (−14.24, 27.85), and −20.16±34.23% (−23.83, 39.05) in the evocalcet 0.5, 1, and 2 mg/day groups and 5.44±25.85% (3.52, 35.39) and −25.86±27.76% (−29.79, 34.15) in the placebo and cinacalcet groups, respectively. The dose-response profile for each evocalcet group vs placebo showed statistically significant differences for all contrast patterns. Whole PTH, corrected calcium, ionized calcium, phosphorus, and intact fibroblast growth factor 23 decreased after treatment initiation in the evocalcet and cinacalcet groups. Adverse events were observed in 30%–50% of patients (all groups). Incidence of adverse events was similar among all groups except for decreased calcium, which occurred more frequently in the evocalcet 2 mg and cinacalcet groups.

Conclusions

The dose response and safety of all administered doses of evocalcet were confirmed, as well as the efficacy of evocalcet ≥1 mg in a strictly Japanese sample of HDSHPT. Therefore, evocalcet 1 mg was considered appropriate as an initial dose for HDSHPT.

Assessment of CYP-Mediated Drug Interactions for Evocalcet, a New Calcimimetic Agent, Based on In Vitro Investigations and a Cocktail Study in Humans

Evocalcet is a novel calcimimetic agent for the treatment of secondary hyperparathyroidism (SHPT). This study evaluated the effects of evocalcet on inhibition and induction of cytochrome P450 (CYP) isozymes. Although drug interactions arising from reversible inhibition of CYP isozymes by evocalcet were considered unlikely based on the results of in vitro studies and static model analyses, the potential for evocalcet to cause time‐dependent inhibition of CYP3A or induction of several CYP isozymes could not be ruled out. Therefore, a clinical drug‐drug interaction (DDI) study to evaluate the effects of evocalcet on the pharmacokinetics (PKs) of probe substrates for CYP isozymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, and CYP3A) was conducted in healthy male volunteers using a novel cocktail combination. Evocalcet did not significantly affect the PKs of the probe substrates, confirming that CYP‐mediated interactions were unlikely.

Pharmacology of Parsabiv® (etelcalcetide, ONO-5163/AMG 416), a novel allosteric modulator of the calcium-sensing receptor, for secondary hyperparathyroidism in hemodialysis patients

Etelcalcetide hydrochloride (Parsabiv^®, ONO-5163/AMG 416) is an allosteric modulator of the calcium (Ca)-sensing receptor that was originally produced by KAI Pharmaceuticals Inc. (now Amgen Inc.). It has recently been approved as the first intravenous calcimimetic agent for secondary hyperparathyroidism (SHPT) in many countries. Etelcalcetide is an intravenous injectable drug that can be administered and eliminated through the dialysis circuit in chronic kidney disease patients. In the present study, we evaluated the in vitro pharmacological profile and in vivo parathyroid hormone (PTH)- and Ca-lowering activities of etelcalcetide in a rat 5/6 nephrectomy model of chronic renal insufficiency with SHPT. Etelcalcetide increased the intracellular Ca concentration in HEK-293T cells expressing human Ca-sensing receptor with an EC₅₀ value (95% confidence interval) of 0.53 μM (0.28-1.0 μM) and suppressed PTH secretion from rat parathyroid gland cells with 0.36 μM (0.24-0.54 μM) by activating Ca-sensing receptor. The specificity of etelcalcetide was evaluated by examining its ability to stimulate or inhibit radioligand binding to a panel of 34 off-target proteins. There were no significant changes in the presence of 10 μM etelcalcetide. Furthermore, in a rat 5/6 nephrectomy model of chronic renal insufficiency with SHPT, single intravenous administration of etelcalcetide at 0.3, 1.0, and 3.0 mg/kg decreased plasma PTH and serum Ca levels. Taken together, the present findings identify etelcalcetide as a calcimimetic with potent PTH- and Ca-lowering effects via Ca-sensing receptor agonist activity.

Chronic kidney failure mineral bone disorder leads to a permanent loss of hematopoietic stem cells through dysfunction of the stem cell niche

In chronic kidney disease (CKD), endothelial injury, is associated with disease progression and an increased risk for cardiovascular complications. Circulating cells with vascular reparative functions are hematopoietic and also reduced in CKD. To explore the mechanistic basis behind these observations, we have investigated hematopoietic stem cell (HSC) homeostasis in a mouse model for non-progressive CKD-mineral and bone disorder with experimentally induced chronic renal failure (CRF). In mice subjected to 12 weeks of CRF, bone marrow HSC frequencies were decreased and transplantation of bone marrow cells from CRF donors showed a decrease in long-term HSC repopulation compared to controls. This loss was directly associated with a CRF-induced defect in the HSC niche affecting the cell cycle status of HSC and could not be restored by the PTH-reducing agent cinacalcet. In CRF, frequencies of quiescent (G0) HSC were decreased coinciding with an increase in hematopoietic progenitor cells (HPC) in the S-and G2-phases of cell cycle. Moreover, in CRF mice, HSC-niche supporting macrophages were decreased compared to controls concomitant to impaired B lymphopoiesis. Our data point to a permanent loss of HSC and may provide insight into the root cause of the loss of homeostatic potential in CKD.

Pharmacokinetics of evocalcet in secondary hyperparathyroidism patients receiving hemodialysis: first-in-patient clinical trial in Japan

Purpose

Cinacalcet is a positive allosteric modulator of calcium-sensing receptors in the parathyroid gland and an effective treatment for secondary hyperparathyroidism. However, this agent has considerable side effects and dosage limitations, which impair effective treatment. Therefore, we investigated the pharmacokinetics, pharmacodynamics, and safety of the novel calcimimetic, evocalcet.

Patients and methods

This was a multicenter, open-label study of single oral doses of 1, 4, and 12 mg evocalcet using an intrapatient dose escalation protocol in 29 Japanese secondary hyperparathyroidism patients receiving hemodialysis. Pharmacokinetics was assessed by plasma evocalcet concentrations. Pharmacodynamic evaluations consisted of measuring intact parathyroid hormone, serum corrected calcium, and fibroblast growth factor 23 concentrations. Safety and tolerability were evaluated by the analysis of adverse events (AEs).

Results

After a single 1-, 4-, or 12-mg dose, plasma evocalcet levels increased dose proportionally in a linear manner. Pharmacodynamic analyses showed that evocalcet effectively reduced intact parathyroid hormone and serum corrected calcium levels in a dose-dependent manner. AEs occurred in 31.0%, 28.6%, and 38.5% of patients receiving a single dose of 1, 4, or 12 mg, respectively. Most AEs were mild in severity.

Conclusion

Evocalcet is effective in the short term, has linear pharmacokinetics, and is well tolerated as observed by the low incidence of AEs.

Pharmacodynamics of evocalcet for secondary hyperparathyroidism in Japanese hemodialysis patients

BACKGROUND

This study investigated the pharmacokinetics, pharmacodynamics, and safety of multiple doses of evocalcet in Japanese secondary hyperparathyroidism (SHPT) patients receiving hemodialysis.

METHODS

In this multicenter, open-label study, conducted between August 2013 and March 2014, 27 patients received multiple doses of 1 and 4 mg evocalcet for 14 days, followed by an extension period of multiple doses of 8 and 12 mg evocalcet for 7 days using an intra-patient dose escalation protocol. Pharmacodynamic parameters consisted of measurement of intact parathyroid hormone (PTH), serum-corrected calcium, serum phosphorus and intact fibroblast growth factor 23 concentrations. Safety was assessed by analysis of adverse events.

RESULTS

Plasma evocalcet levels reached steady state 3 days after the first day of administration. Pharmacodynamic analyses showed that evocalcet effectively reduced intact PTH and serum-corrected calcium levels. Adverse events (AEs) occurred in 29.6 and 62.5% of patients receiving multiple doses of 1 or 4 mg, respectively. The AE 'blood calcium decreased' occurred in eight patients (33.0%) after multiple doses of 4 mg. All events were mild, except for one patient with a moderate AE (abnormal liver function) and one patient with a severe adverse drug reaction (blood calcium decreased).

CONCLUSION

Multiple doses of evocalcet reduced intact PTH levels with a concomitant decrease in serum calcium levels. Evocalcet was well tolerated in SHPT patients receiving hemodialysis.

Overview of the 2017 KDIGO CKD-MBD Update: Practice Implications for Adult Hemodialysis Patients

Renal dietitians play a pivotal role in the ongoing management of chronic kidney disease in patients on hemodialysis. Awareness of changes to clinical practice guidelines that may impact laboratory parameters associated with chronic kidney disease-mineral and bone disorder is important for optimal patient care. In this article, the Kidney Disease: Improving Global Outcomes 2017 Clinical Practice Guideline Update recommendations related to the treatment of secondary hyperparathyroidism in adults on hemodialysis are reviewed and treatment implications for renal dietitians discussed. Specific attention is given to the integration of updated recommendations such as the use of calcimimetics as part of a combination approach to the existing treatment paradigm. Renal dietitians can directly apply the updated clinical recommendations in the evaluation of diet composition; food additives; medication adherence challenges with phosphate binder type and use and serial monitoring of phosphorus, calcium, and parathyroid hormone levels to inform clinical decisions on treatment options for patients.

Treatment of secondary hyperparathyroidism in patients on hemodialysis using a novel synthetic peptide calcimimetic, etelcalcetide: a short-term clinical study

Objective

Secondary hyperparathyroidism (SHPT) is a major complication in patients with chronic kidney disease (CKD). SHPT is related to chronic kidney disease-mineral bone disorder, leading to increased morbidity and mortality. Etelcalcetide is intravenously administered at the end of hemodialysis (HD). Etelcalcetide differs from the oral calcimimetic cinacalcet because it reduces gastrointestinal adverse events, thereby improving therapeutic effects. Etelcalcetide has only been approved by the U.S. Food and Drug Administration for several months. Therefore, there have only been a few reports regarding treatment of SHPT using etelcalcetide. This study aimed to evaluate the efficacy of etelcalcetide in patients on HD with SHPT.

Methods

Nine patients on HD (four men and five women, aged 58 ± 10 years) were enrolled in this study. All of the patients received etelcalcetide (5–10 mg, three times a week after HD). The observation period was 4.4 ± 1.0 months.

Results

All of the patients showed a significant reduction in serum parathyroid hormone levels during the observation period (−59% ± 20%). No significant adverse effects were observed.

Conclusions

Although this study had an uncontrolled small group and a short observation period, our results suggest that etelcalcetide could be a promising agent for SHPT treatment.

Treatment of secondary hyperparathyroidism: How do cinacalcet and etelcalcetide differ?

Secondary hyperparathyroidism (SHPT), commonly encountered in patients receiving maintenance dialysis, is associated with numerous adverse outcomes, including mortality. Calcimimetics, agents that act on the calcium sensing receptor (CaSR), were designed to overcome limitations in the use of vitamin D sterols to treat SHPT, and have demonstrated efficacy in reducing levels of PTH in randomized trials. Currently available calcimimetics include oral cinacalcet and the recently approved intravenously administered agent, etelcalcetide. While cinacalcet is an allosteric modulator of the CaSR, etelcalcetide acts as a direct CaSR agonist. Etelcalcetide's properties allow it to be administered intravenously thrice weekly at the end of a hemodialysis treatment session. Etelcalcetide has recently been shown to be more potent than cinacalcet in reducing PTH levels. However, etelcalcetide appears, like cinacalcet, to cause gastrointestinal intolerance. Additionally, etelcalcetide, which appears to reduce calcium substantially more than cinacalcet does, can prolong the QTc electrocardiographic interval. While etelcalcetide is very effective at reducing PTH levels, the current climate of dialysis cost containment in the United States may limit its widespread use. This review compares and contrasts the pharmacologic characteristics of cinacalcet and etelcalcetide, discusses the results of clinical trials involving these drugs, and posits implications for their use for clinical practice.

Sucroferric oxyhydroxide for the treatment of hyperphosphatemia

INTRODUCTION

Sucroferric oxyhydroxide is a non-calcium, iron-based phosphate binder indicated for the treatment of hyperphosphatemia in patients with chronic kidney disease undergoing dialysis. Areas covered: Herein, the preclinical development and clinical data for sucroferric oxyhydroxide are reviewed, including the key data from the Phase III registration study and the latest evidence from the real-world clinical setting. Expert opinion: Sucroferric oxyhydroxide displays potent phosphate-binding capacity and clinical studies demonstrate its effectiveness for the long-term reduction of serum phosphorus levels in dialysis patients. Observational study data also show that sucroferric oxyhydroxide provides effective serum phosphorus control for hyperphosphatemic patients in the real-world clinical setting. The serum phosphorus reductions with sucroferric oxyhydroxide can be achieved with a relatively low pill burden in comparison with other phosphate binders, which may translate into better treatment adherence in clinical practice. The Phase III data also indicate that sucroferric oxyhydroxide has a favorable impact on other chronic kidney disease-related mineral bone disease parameters, including a fibroblast growth factor-23-lowering effect. Sucroferric oxyhydroxide is well tolerated and associated with low systemic iron absorption, minimizing the potential for iron accumulation or overload. These attributes render sucroferric oxyhydroxide an attractive non-calcium-containing phosphate binder for the treatment of hyperphosphatemia.

Parathyroidectomy in the Management of Secondary Hyperparathyroidism

Secondary hyperparathyroidism develops in CKD due to a combination of vitamin D deficiency, hypocalcemia, and hyperphosphatemia, and it exists in nearly all patients at the time of dialysis initiation. There is insufficient data on whether to prefer vitamin D analogs compared with calcimimetics, but the available evidence suggests advantages with combination therapy. Calcium derangements, patient adherence, side effects, and cost limit the use of these agents. When parathyroid hormone level persists >800 pg/ml for >6 months, despite exhaustive medical interventions, monoclonal proliferation with nodular hyperplasia is likely present along with decreased expression of vitamin D and calcium-sensing receptors. Hence, surgical parathyroidectomy should be considered, especially if concomitant disorders exist, such as persistent hypercalcemia or hyperphosphatemia, tissue or vascular calcification including calciphylaxis, and/or worsening osteodystrophy. Parathyroidectomy is associated with 15%-57% greater survival in patients on dialysis, and it also improves hypercalcemia, hyperphosphatemia, tissue calcification, bone mineral density, and health-related quality of life. The parathyroidectomy rate in the United States declined to approximately seven per 1000 dialysis patient-years between 2002 and 2011 despite an increase in average parathyroid hormone levels, reflecting calcimimetics introduction and uncertainty regarding optimal parathyroid hormone targets. Hospitalization rates are 39% higher in the first postoperative year. Hungry bone syndrome occurs in approximately 25% of patients on dialysis, and profound hypocalcemia requires high doses of oral and intravenous calcium along with calcitriol supplementation. Total parathyroidectomy with autotransplantation carries a higher risk of permanent hypocalcemia, whereas risk of hyperparathyroidism recurrence is higher with subtotal parathyroidectomy. Given favorable long-term outcomes from observational parathyroidectomy cohorts, despite surgical risk and postoperative challenges, it is reasonable to consider parathyroidectomy in more patients with medically refractory secondary hyperparathyroidism.

Role of etelcalcetide in the management of secondary hyperparathyroidism in hemodialysis patients: a review on current data and place in therapy

Secondary hyperparathyroidism (sHPT) is a frequently occurring severe complication of advanced kidney disease. Its clinical consequences include extraskeletal vascular and valvular calcifications, changes in bone metabolism resulting in renal osteodystrophy, and an increased risk of cardiovascular morbidity and mortality. Calcimimetics are a cornerstone of parathyroid hormone (PTH)-lowering therapy, as confirmed by the recently updated 2017 Kidney Disease: Improving Global Outcomes chronic kidney disease – mineral and bone disorder clinical practice guidelines. Contrary to calcitriol or other vitamin D-receptor activators, calcimimetics reduce PTH without increasing serum-calcium, phosphorus, or FGF23 levels. Etelcalcetide is a new second-generation calcimimetic that has been approved for the treatment of sHPT in adult hemodialysis patients. Whereas the first-generation calcimimetic cinacalcet is taken orally once daily, etelcalcetide is given intravenously thrice weekly at the end of the hemodialysis session. Apart from improving drug adherence, etelcalcetide has proven to be more effective in lowering PTH when compared to cinacalcet, with an acceptable and comparable safety profile. The hope for better gastrointestinal tolerance with intravenous administration did not come true, as etelcalcetide did not significantly mitigate the adverse gastrointestinal effects associated with cinacalcet. Enhanced adherence and strong reductions in PTH, phosphorus, and FGF23 could set the stage for a future large randomized controlled trial to demonstrate that improved biochemical control of mineral metabolism with etelcalcetide in hemodialysis patients translates into cardiovascular and survival benefits and better health-related quality of life.

Discovery of evocalcet, a next-generation calcium-sensing receptor agonist for the treatment of hyperparathyroidism

The calcium-sensing receptor (CaSR) plays an important role in sensing extracellular calcium ions and regulating parathyroid hormone secretion by parathyroid gland cells, and the receptor is a suitable target for the treatment of hyperparathyroidism. Cinacalcet hydrochloride is a representative CaSR agonist which widely used for the hyperparathyroidism. However, it has several issues to clinical use, such as nausea/vomiting and strong inhibition of CYP2D6. We tried to improve these issues of cinacalcet for a new pharmaceutical agent as a preferable CaSR agonist. Optimization from cinacalcet resulted in the identification of pyrrolidine compounds and successfully led to the discovery of evocalcet as an oral allosteric CaSR agonist. Evocalcet, which exhibited highly favorable profiles such as CaSR agonistic activity and good DMPK profiles, will provide a novel therapeutic option for secondary hyperparathyroidism.

Association of Nonoxidized Parathyroid Hormone with Cardiovascular and Kidney Disease Outcomes in Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

In patients with CKD, elevated plasma parathyroid hormone (PTH) levels are associated with greater cardiovascular morbidity and mortality. However, the reference method for PTH measurement is disputed. It has been argued that measurement of nonoxidized PTH better reflects biologically active PTH than measurements with conventional assays.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

PTH and nonoxidized PTH levels were measured at study baseline in 535 patients with CKD with an eGFR range between 89 and 15 ml/min per 1.73 m2. Patients were followed over 5.1 years for the occurrence of acute heart failure, atherosclerotic events, CKD progression (doubling of serum creatinine or initiation of RRT), or all-cause death.

RESULTS

Atherosclerotic events, acute heart failure, CKD progression, and deaths from any cause occurred in 116, 58, 73, and 85 patients, respectively. In Kaplan-Meier analyses, patients at the highest PTH and nonoxidized-PTH tertile (79-543 and 12-172 pg/ml, respectively) showed a higher rate of atherosclerotic events, acute heart failure, CKD progression, and death from any cause. After adjustment for eGFR and albuminuria, nonoxidized PTH was no longer associated with atherosclerotic events (hazard ratio third versus first tertile, 1.04 [95% confidence intervals, 0.62-1.75]), acute heart failure (hazard ratio third versus first tertile, 1.24 [95% confidence intervals, 0.59-2.62]), CKD progression (hazard ratio third versus first tertile, 0.93 [95% confidence intervals, 0.46-1.90]), and death from any cause (hazard ratio third versus first tertile, 1.23 [95% confidence intervals, 0.66-2.31]), and PTH lost its association with atherosclerotic events (hazard ratio third versus first tertile, 0.80 [95% confidence intervals, 0.46-1.38]) and CKD progression (hazard ratio third versus first tertile, 0.99 [95% confidence intervals, 0.46-2.10]), although it remained associated with acute heart failure (hazard ratio third versus first tertile, 2.76 [95% confidence intervals, 1.11-6.89]) and all-cause death (hazard ratio third versus first tertile, 2.35 [95% confidence intervals, 1.13-4.89]). After further adjustment for cardiovascular and kidney risk factors, PTH remained associated with all-cause death (hazard ratio third versus first tertile, 2.79 [95% confidence intervals, 1.32-5.89]), but with no other end point.

CONCLUSIONS

In a cohort of patients with CKD, PTH was associated with all-cause mortality; there was no association of nonoxidized PTH with any of the clinical outcomes examined.

A novel calcimimetic agent, evocalcet (MT-4580/KHK7580), suppresses the parathyroid cell function with little effect on the gastrointestinal tract or CYP isozymes in vivo and in vitro

Cinacalcet hydrochloride (cinacalcet), an oral calcimimetic agent has been widely used for the management of secondary hyperparathyroidism (SHPT) in chronic kidney disease (CKD). In sharp contrast to vitamin D receptor activators, cinacalcet suppresses SHPT without inducing hypercalcemia or hyperphosphatemia. Nevertheless, some patients remain refractory to SHPT with this agent, as the dose cannot be sufficiently increased due to gastrointestinal symptoms. In order to resolve this issue, we have developed a newly synthesized calcimimetic agent, evocalcet (MT-4580/KHK7580). In a rat model of CKD induced by 5/6 nephrectomy, oral administration of evocalcet efficiently suppressed the secretion of parathyroid hormone (PTH). With regard to the gastro-intestinal effects, cinacalcet induced a significant delay in gastric emptying in rats, while evocalcet did no marked effects on it. Evocalcet also demonstrated the less induction of emesis compared to cinacalcet in common marmosets. The pharmacological effects of evocalcet were observed at lower doses because of its higher bioavailability than cinacalcet, which may have contributed to the reduced GI tract symptoms. In addition, evocalcet showed no substantial direct inhibition of any CYP isozymes in in vitro liver microsome assay, suggesting a better profile in drug interactions than cinacalcet that inhibits cytochrome P450 (CYP) 2D6. These findings suggest that evocalcet can be a better alternative to cinacalcet, an oral calcimimetic agent, with a wider safety margin.

A phase 3, multicentre, randomized, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy and safety of etelcalcetide (ONO-5163/AMG 416), a novel intravenous calcimimetic, for secondary hyperparathyroidism in Japanese haemodialysis patients

Background

Secondary hyperparathyroidism (SHPT) is a major complication associated with chronic kidney disease. We evaluated the efficacy and safety of etelcalcetide (ONO-5163/AMG 416), a novel intravenous calcimimetic, in Japanese haemodialysis patients with SHPT.

Methods

In this phase 3, multicentre, randomized, double-blind, placebo-controlled, parallel-group study, etelcalcetide was administered three times per week at an initial dose of 5 mg, and subsequently adjusted to doses between 2.5 and 15 mg at 4-week intervals for 12 weeks. A total of 155 SHPT patients with serum intact parathyroid hormone (iPTH) levels ≥300 pg/mL were assigned to receive etelcalcetide (n = 78) or placebo (n = 77). The primary endpoint was the proportion of patients with decreased serum iPTH to the target range proposed by the Japanese Society for Dialysis Therapy (60–240 pg/mL). The major secondary endpoint was the proportion of patients with ≥30% reductions in serum iPTH from baseline.

Results

The proportion of patients meeting the primary endpoint was significantly higher for etelcalcetide (59.0%) versus placebo (1.3%). Similarly, the proportion of patients meeting the major secondary endpoint was significantly higher for etelcalcetide (76.9%) versus placebo (5.2%). Serum albumin-corrected calcium, phosphorus and intact fibroblast growth factor-23 levels were decreased in the etelcalcetide group. Nausea, vomiting and symptomatic hypocalcaemia were mild with etelcalcetide. Serious adverse events related to etelcalcetide were not observed.

Conclusions

This study demonstrated the efficacy and safety of etelcalcetide. As the only available intravenous calcium-sensing receptor agonist, etelcalcetide is likely to provide a new treatment option for SHPT in haemodialysis patients.

Discovery and Development of Calcimimetic and Calcilytic Compounds

The extracellular calcium receptor (CaR) is a G protein-coupled receptor (GPCR) and the pivotal molecule regulating systemic Ca²⁺ homeostasis. The CaR was a challenging target for drug discovery because its physiological ligand is an inorganic ion (Ca²⁺) rather than a molecule so there was no structural template to guide medicinal chemistry. Nonetheless, small molecules targeting this receptor were discovered. Calcimimetics are agonists or positive allosteric modulators of the CaR, while calcilytics are antagonists and all to date are negative allosteric modulators. The calcimimetic cinacalcet was the first allosteric modulator of a GPCR to achieve regulatory approval and is a first-in-class treatment for secondary hyperparathyroidism in patients on dialysis, and for hypercalcemia in some forms of primary hyperparathyroidism. It is also useful in treating some rare genetic diseases that cause hypercalcemia. Two other calcimimetics are now on the market (etelcalcetide) or under regulatory review (evocalcet). Calcilytics stimulate the secretion of parathyroid hormone and were initially developed as treatments for osteoporosis. Three different calcilytics of two different chemotypes failed in clinical trials due to lack of efficacy. Calcilytics are now being repurposed and might be useful in treating hypoparathyroidism and several rare genetic diseases causing hypocalcemia. The challenges ahead for medicinal chemists are to design compounds that select conformations of the CaR that preferentially target a particular signalling pathway and/or that affect the CaR in a tissue-selective manner.

Clinical Pharmacokinetics and Pharmacodynamics of Etelcalcetide, a Novel Calcimimetic for Treatment of Secondary Hyperparathyroidism in Patients With Chronic Kidney Disease on Hemodialysis

Etelcalcetide, a d-amino acid peptide, is an intravenous calcimimetic approved for the treatment of secondary hyperparathyroidism. Etelcalcetide binds the calcium-sensing receptor and increases its sensitivity to extracellular calcium, thereby decreasing secretion of parathyroid hormone (PTH) by chief cells. Etelcalcetide and its low-molecular-weight transformation products are rapidly cleared by renal excretion in healthy subjects, but clearance is substantially reduced and dependent on hemodialysis in end-stage renal disease. The effective half-life is 3-5 days in patients undergoing hemodialysis 3 times a week. A clinical study using a single microtracer intravenous dose of [¹⁴ C]etelcalcetide indicated that 60% of the administered dose was eliminated in dialysate. Etelcalcetide undergoes reversible disulfide exchange with serum albumin to form a serum albumin peptide conjugate that is too large (67 kDa) to be dialyzed, until a subsequent exchange forms etelcalcetide or a low-molecular-weight transformation product. This exchange from albumin is apparent after hemodialysis, when it partially restores etelcalcetide concentrations in plasma. Etelcalcetide has no known risks for drug-drug interactions. In phase 3 studies, 74%-75% of hemodialysis patients with secondary hyperparathyroidism who received etelcalcetide achieved a >30% PTH reduction from baseline versus 8%-10% of patients who received placebo. The pharmacokinetics and pharmacodynamics of etelcalcetide in hemodialysis patients supports a 5-mg starting dose administered after hemodialysis and uptitration in 2.5- or 5-mg increments every 4 weeks to a maximum dose of 15 mg 3 times a week.

CKD-MBD management: what is the role of parathyroidectomy? Results from a nationwide survey in Italy

We herein report on a nationwide survey conducted in Italy to investigate the use of parathyroidectomy (PTX). In spite of the availability of newer and more effective drugs to control chronic kidney disease mineral bone disorder (CKD-MBD) biochemical abnormalities, PTX still remains a resource for nephrologists to use. However, observational analyses suggest that in recent years there has been a constant decline in the number of patients undergoing PTX. The reasons are not clear, though the increasing age and number of comorbidities of dialysis patients may partly explain this trend. Poor adherence to guidelines and/or geographical as well as logistic factors may also contribute to the lower use of PTX. The working group on CKD-MBD of the Italian Society of Nephrology launched a nationwide survey to investigate clinical practice patterns for PTX in Italy and identify modifiable factors that may limit accessibility to surgery.

The Effect of Vitamin D Supplementation on Bone Metabolic Markers in Chronic Kidney Disease

Use of active forms of vitamin D is advocated in patients with chronic kidney disease (CKD) for treatment of mineral bone disease because of the presumption that native forms of vitamin D would not undergo significant activation to calcitriol, the most active biological form of vitamin D. We present secondary analysis looking at bone turnover in subjects who completed the randomized, double blind, placebo-controlled trial investigating the effect of cholecalciferol supplementation on vascular function in nondiabetic CKD stage G3-G4 and vitamin D ≤20 ng/mL (Clinical Trials Registry of India: CTRI/2013/05/003648). Patients were randomized (1:1) to receive either two directly observed oral doses of 300,000 IU of cholecalciferol or matching placebo at baseline and 8 weeks. Of the 120 subjects enrolled, 58 in the cholecalciferol group and 59 in the placebo group completed the study. At 16 weeks, the serum 25(OH)D and 1,25(OH)₂ D levels increased in the cholecalciferol group but not in the placebo group (between-group difference in mean change: 23.40 ng/mL; 95% CI, 19.76 to 27.06; p < 0.001, and 14.98 pg/mL; 95% CI, 4.48 to 27.18; p = 0.007, respectively). Intact parathyroid hormone (iPTH) decreased in the cholecalciferol group (between-group difference in mean change -100.73 pg/mL (95% CI, -150.50 to -50.95; p < 0.001). Serum total and bone-specific alkaline phosphatase (SAP, BAP) and serum C-terminal cross-linked collagen type I telopeptides (CTX-1) were significantly reduced in cholecalciferol group (between group difference for change in mean: -20.25 U/L; 95% CI, -35.14 to -5.38 U/L; p = 0.008 for SAP; -12.54 U/L; 95% CI, -22.09 to -2.98 U/L; p = 0.013 for BAP; and -0.21 ng/mL; 95% CI, -0.38 to -0.05 ng/mL; p = 0.05 for CTX-1). Correlation analysis showed significant correlation of Δ25(OH)D with ΔiPTH (r = -0.409, p < 0.0001), Δ1,25(OH)₂ D (r = 0.305, p = 0.001), ΔSAP (r = -0.301, p = 0.002), ΔBAP (r = -0.264, p = 0.004), and ΔCTX-1 (r = -0.210, p = 0.0230). Cholecalciferol supplementation corrects vitamin D deficiency and is effective in lowering serum intact parathyroid hormone and bone turnover markers in early stages of CKD. © 2017 American Society for Bone and Mineral Research.

Managing hyperparathyroidism in hemodialysis: role of etelcalcetide

Secondary hyperparathyroidism (SHPT) is common in patients receiving maintenance hemodialysis and is associated with adverse outcomes. Currently, SHPT is managed by reducing circulating levels of phosphate with oral binders and parathyroid hormone (PTH) with vitamin D analogs and/or the calcimimetic cinacalcet. Etelcalcetide, a novel calcimimetic administered intravenously (IV) at the end of a hemodialysis treatment session, effectively reduces PTH in clinical trials when given thrice weekly. Additional clinical effects include reductions in circulating levels of phosphate and FGF-23 and an improved profile of markers of bone turnover. However, despite being administered IV, etelcalcetide appears to be associated with rates of nausea and vomiting comparable to those of cinacalcet. Additionally, etelcalcetide, relative to placebo, causes hypocalcemia and prolonged electrocardiographic QT intervals, effects that must be considered when contemplating its use. Etelcalcetide likely has a role in treating hemodialysis patients with uncontrolled SHPT or with hypercalcemia or hyperphosphatemia receiving activated vitamin D compounds. However, its use should be at least partially constrained by consideration of the risk of hypocalcemia and resultant prolonged QT intervals in vulnerable patients. Because of its effectiveness as a PTH-reducing agent administered in the dialysis unit, etelcalcetide represents a potentially promising new therapeutic approach to the often vexing problem of SHPT in hemodialysis patients. However, whether its use is associated with changes in surrogate clinical end points, such as effects on rates of parathyroidectomy, fracture, vascular calcification, or mortality or on quality of life, remains to be studied.

The Parathyroid Gland and Heart Disease

The parathyroid glands are critical to maintaining calcium homeostasis through actions of parathyroid hormone (PTH). Recent clinical and molecular research has shown that direct and indirect actions of PTH also affect the heart and vasculature through downstream actions of G protein-coupled receptors in the myocardium and endothelial cells. Patients with disorders of the parathyroid gland have higher incidences of hypertension, arrhythmias, left ventricular hypertrophy, heart failure, and calcific disease which translate into increased cardiac morbidity and mortality. Importantly, clinical research also suggests that early treatment of parathyroid disorders through medical or surgical management may reverse cardiovascular remodeling and mitigate cardiac risk factors.