A Japanese approach for CKD-MBD

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.

Persistent uncertainties in optimal treatment approaches of secondary hyperparathyroidism and hyperphosphatemia in patients with chronic kidney disease

PURPOSE OF REVIEW

This review is a critical analysis of treatment results obtained in clinical trials conducted in patients with chronic kidney disease (CKD) and secondary hyperparathyroidism (SHPT), hyperphosphatemia, or both.

RECENT FINDINGS

Patients with CKD have a high mortality rate. The disorder of mineral and bone metabolism (CKD-MBD), which is commonly present in these patients, is associated with adverse outcomes, including cardiovascular events and mortality. Clinical trials aimed at improving these outcomes by modifying CKD-MBD associated factors have most often resulted in disappointing results. The complexity of CKD-MBD, where many players are closely interconnected, might explain these negative findings. We first present an historical perspective of current knowledge in the field of CKD-MBD and then examine potential flaws of past and ongoing clinical trials targeting SHPT and hyperphosphatemia respectively in patients with CKD.

An update on phosphate binders for the treatment of hyperphosphatemia in chronic kidney disease patients on dialysis: a review of safety profiles

INTRODUCTION

Hyperphosphatemia is an inevitable complication for patients undergoing dialysis, as is the resulting need for treatment with phosphate binders. Currently, various phosphate binders are clinically available. In addition to their phosphate-lowering activity, individual phosphate binders have differing safety profiles and off-target actions.

AREAS COVERED

This paper reviews the safety of phosphate binders and issues to be resolved.

EXPERT OPINION

Calcium-based phosphate binders are well tolerated but may increase calcium overload risk. Sevelamer reduces serum cholesterol levels and exerts anti-inflammatory effects. Compared to sevelamer, bixalomer is associated with fewer gastrointestinal symptoms. Aluminum-containing binders, lanthanum carbonate, and sucroferric oxyhydroxide exhibit strong phosphate-lowering activity. Although ferric citrate reduces erythropoiesis-stimulating agents and intravenous iron doses, its use requires monitoring of iron metabolic markers to avoid overload. Occasionally, combined use of multiple phosphate binders can offer the advantages of each phosphate binder while minimizing their drawbacks; thus, this may be desirable according to individual patients' conditions and comorbidities. However, increased pill burden and nonadherence to phosphate binders emerge as new problems. We expect that novel therapeutic strategies will be developed to resolve these issues.

Evocalcet with vitamin D receptor activator treatment for secondary hyperparathyroidism

This ad hoc analysis of a previously conducted phase 3 head-to-head comparison study of evocalcet and cinacalcet in secondary hyperparathyroidism patients undergoing maintenance hemodialysis evaluated the efficacy and safety of combined once-daily oral evocalcet and intravenous vitamin D receptor activator treatment stratified by weekly vitamin D receptor activator dose (117, 45, and 91 patients in no, low [< 1.5 μg], and high [≥ 1.5 μg] dose groups, respectively). Effects of vitamin D receptor activator were assessed on the basis of intact parathyroid hormone, corrected calcium, phosphorus, and fibroblast growth factor-23 levels; percent changes from baseline; proportions of patients who achieved target intact parathyroid hormone, corrected calcium, and phosphorus at Weeks 28–30; and adverse drug reactions. Intact parathyroid hormone, corrected calcium, phosphorus, and fibroblast growth factor-23 levels decreased in all groups; phosphorus and fibroblast growth factor-23 levels remained high in the high dose group. In the low and high dose groups, greater proportions of patients achieved the corrected calcium target compared with the no dose group (p = 0.043). Ratios of intact-to-C-terminal fibroblast growth factor-23 decreased in all groups. In low and high dose groups, hypocalcemia was less common than in the no dose group (p = 0.014). Evocalcet with concomitant vitamin D receptor activator demonstrated benefits such that more patients achieved the corrected calcium target and exhibited decreased fibroblast growth factor-23 synthesis; the incidence of hypocalcemia also decreased.

Clinical trial registration: ClinicalTrials.gov (NCT02549391) and JAPIC (JapicCTI-153013).

Effect of Tenapanor on Phosphate Binder Pill Burden in Hemodialysis Patients

Introduction

The current management of hyperphosphatemia with phosphate binders is associated with insufficient phosphorus control and a significant pill burden. Tenapanor, a first-in-class, phosphate absorption inhibitor, is expected to control phosphorus and decrease pill burden because of its small pill size and twice daily dosing regimen. This study evaluated tenapanor effectiveness on reducing the phosphate binder pill burden during a 26-week treatment period in Japanese hemodialysis patients.

Methods

In this multicenter, open-label, single-arm study, hemodialysis patients whose serum phosphorus level was 3.5 to 7.0 mg/dl received tenapanor 30 mg twice daily orally added to their phosphate binder regimen. The phosphate binder dosage was adjusted to achieve a serum phosphorus level within the baseline range of ±0.5 mg/dl. The primary end point was the percentage of patients who achieved a ≥30% decrease in the number of phosphate binders and tenapanor tablets prescribed daily compared with the number of phosphate binder tablets at baseline.

Results

Of the 67 patients enrolled, 43 completed the study. At baseline, the mean total number of phosphate binder tablets per day was 14.7, which decreased to 3.0 tablets per day at week 26. The primary end point was achieved in 71.6% of patients (P < 0.001). The phosphate binder was completely switched to tenapanor in 28.4% of patients (P < 0.001). The mean phosphorus levels were relatively well controlled (5.19 and 4.71 mg/dl at baseline and week 26, respectively). The most frequent drug-related adverse event (AE) was diarrhea (74.6%).

Conclusion

Tenapanor provided effective phosphorus control and decreased the number of phosphate binder tablets. The management of drug-related diarrhea will facilitate more widespread use of tenapanor.

A Survey of Drug Burden in Patients Undergoing Maintenance Hemodialysis in Japan

Objective This report presents a part of a survey pertaining to drug burden in maintenance hemodialysis patients in Japan. Methods A patient-reported questionnaire-based survey was conducted from September to November 2016 in six regions in Japan. Patients A total of 700 patients (50-79 years old) on maintenance hemodialysis for >3 years and members of the Japan Association of Kidney Disease Patients (JAKDP) were provided with the questionnaire. They were randomly selected using stratified sampling according to patient distribution observed from the Japanese Society for Dialysis Therapy Renal Data Registry (JSDT JRDR). Results A total of 524 (74.9%) patient questionnaires were evaluated [mean (standard deviation; SD) age, 66.6 (7.2) years; males, 63.4%; dialysis vintage, 16.9 (9.1) years]. Patients' age, gender, and regional distribution were similar to the JSDT JRDR. They were taking an average (SD) of 16.4 (8.34) and 16.3 (8.55) oral medications/day on dialysis and nondialysis days, respectively. A majority of the patients were taking ≥10 oral medications/day on dialysis (75.1%) and nondialysis (74.4%) days, with phosphate binders being the most taken (7.0 tablets/day). A similar proportion (74.4%, 72.9%, respectively) was taking ≥6 different types of oral medications/day. Most patients were taking oral medications 3 (31%, 33%), 4 (24%, 22%), and ≥5 times (31%, 30%) a day, respectively. The drug burden was similar on dialysis and nondialysis days and did not vary with dialysis vintage. Conclusion The number, type, and frequency of oral medications in maintenance hemodialysis patients are high in Japan. The proportion of phosphate binders was highest among the prescription medications.

Clinical and Practical Use of Calcimimetics in Dialysis Patients With Secondary Hyperparathyroidism

CKD and CKD-related mineral and bone disorders (CKD-MBDs) are associated with high cardiovascular and mortality risks. In randomized clinical trials (RCTs), no single drug intervention has been shown to reduce the high mortality risk in dialysis patients, but several robust secondary analyses point toward important potential beneficial effects of controlling CKD-MBD-related factors and secondary hyperparathyroidism. The advent of cinacalcet, which has a unique mode of action at the calcium-sensing receptor, represented an important step forward in controlling CKD-MBD. In addition, new RCTs have conclusively shown that cinacalcet improves achievement of target levels for all of the metabolic abnormalities associated with CKD-MBD and may also attenuate the progression of vascular and valvular calcifications in dialysis patients. However, a final conclusion on the effect of cinacalcet on hard outcomes remains elusive. Tolerance of cinacalcet is limited by frequent secondary side effects such as nausea, vomiting, hypocalcemia and oversuppression of parathyroid hormone, which may cause some management difficulties, especially for those lacking experience with the drug. Against this background, this review aims to summarize the results of studies on cinacalcet, up to and including the publication of the recent ADVANCE and EVOLVE RCTs, as well as recent post hoc analyses, and to offer practical guidance on how to improve the clinical management of the most frequent adverse events associated with cinacalcet, based on both currently available information and personal experience. In addition, attention is drawn to less common secondary effects of cinacalcet treatment and advisable precautions.

Effect of parathyroid hormone on serum magnesium levels: the neglected relationship in hemodialysis patients with secondary hyperparathyroidism

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is an important complication in patients with end-stage renal disease. Since recent studies have shown that magnesium (Mg) disturbance plays an important role in CKD-MBD and cardiovascular mortality, the interest on magnesium has grown recently. Although much concern focused on the effect of Mg on parathyroid hormone (PTH) levels, however, the influence of PTH on serum Mg levels is nearly unexplored. To evaluate the effect of PTH on serum Mg levels, we first described the relationship between serum Mg and PTH in secondary hyperparathyroidism. Besides, we also monitored the changes of serum Mg concentration after parathyroidectomy (PTX) in 23 patients. In our study, we found that hypermagnesemia (>2.5 mg/dL) occurred in up to 44% of cases and hypomagnesemia did not present. No statistically significant correlations were found between serum Mg levels and PTH (r = -0.143, p = 0.134). Correlation analysis and regression analysis suggested that the derangement of magnesium homeostasis was consistent with the derangement of calcium/phosphorus homeostasis. However, after PTX, serum magnesium levels dropped immediately after the surgery, minimally at the first day and gradually restored from the third day. The changes of serum Mg after surgery was positive correlated with the changes of serum phosphate (r = 0.558, p = 0.003). Taken altogether, our data suggested that the therapeutic strategies to achieve optimum serum magnesium levels in CKD-MBD should take into account the varying stages of disease development since PTH could also influence magnesium metabolism and this problem might be important in severe secondary hyperparathyroidism.

Relationship between parathyroid mass and parathyroid hormone level in hemodialysis patients with secondary hyperparathyroidism

Background

To evaluate the influence of parathyroid mass on the regulation of parathyroid hormone (PTH) secretion, we investigated the relationship between the resected parathyroid gland in total parathyroidectomy and the parathyroid hormone level in hemodialysis patients with secondary hyperparathyroidism.

Methods

From January 2009 to July 2014, 223 patients undergoing total parathyroidectomy were included. The size and the weight of parathyroid gland were measured during the operation.

Results

874 parathyroid glands were removed. A positive correlation was identified between the size and the weight of resected parathyroid glands. We found that both the preoperative PTH and the reduction of PTH were significantly correlated with the size and the weight of parathyroid glands in a positive manner. However, in the subgroup of patients with PTH < 1000 pg/ml, no significant correlation was found.

Conclusions

Larger parathyroid gland secretes more PTH and high level of serum PTH usually indicated that surgical removal might be required. However, since PTH levels could be influenced by the pharmaceutical drug, the large size of parathyroid gland might be used as a much more appropriate guide that indicates the requirement of surgery treatment even when the parathyroid hormone was less than 1000 pg/ml.