Head-to-head comparison of the new calcimimetic agent evocalcet with cinacalcet in Japanese hemodialysis patients with secondary hyperparathyroidism

Current therapeutic approach of chronic kidney disease-mineral and bone disorder

Chronic kidney disease (CKD) has emerged as one of the leading noncommunicable diseases affecting >10% of the population worldwide. Bone and mineral disorders are a common complication among patients with CKD resulting in a poor life quality, high fracture risk, increased morbidity and cardiovascular mortality. According to Kidney Disease: Improving Global Outcomes, renal osteodystrophy refers to changes in bone morphology found in bone biopsy, whereas CKD-mineral and bone disorder (CKD-MBD) defines a complex of disturbances including biochemical and hormonal alterations, disorders of bone and mineral metabolism and extraskeletal calcification. As a result, the management of CKD-MBD should focus on the aforementioned parameters, including the treatment of hyperphosphatemia, hypocalcemia, abnormal PTH and vitamin D levels. Regarding the bone fragility fractures, osteoporosis and renal osteodystrophy, which constitute the bone component of CKD-MBD, anti-osteoporotic agents constitute the mainstay of treatment. However, a thorough elucidation of the CKD-MBD pathogenesis is crucial for the ideal personalized treatment approach. In this paper, we review the pathology and management of CKD-MBD based on the current literature with special attention to recent advances.

Secondary hyperparathyroidism in chronic kidney disease: pathophysiology, current treatments and investigational drugs

INTRODUCTION

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD). It begins as an adaptive increase in parathyroid hormone levels to prevent calcium and phosphate derangements. Over time, this condition becomes maladaptive and is associated with increased morbidity and mortality. Current therapies encompass phosphate-lowering strategies, vitamin D analogues, calcimimetics and parathyroidectomy. These approaches harbor inherent limitations, stimulating interest in the development of new drugs for SHPT to overcome these limitations and improve survival and quality of life among CKD patients.

AREAS COVERED

This review delves into the main pathophysiological mechanisms involved in SHPT, alongside the treatment options that are currently available and under active investigation. Data presented herein stem from a comprehensive search conducted across PubMed, Web of Science, ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) spanning from 2000 onwards.

EXPERT OPINION

The advancements in investigational drugs for SHPT hold significant promise for enhancing treatment efficacy while minimizing side effects associated with conventional therapies. Although several challenges still hinder their adoption in clinical practice, ongoing research will likely continue to expand the available therapeutic options, refine treatment strategies, and tailor them to individual patient profiles.

Effects of active vitamin D analogs and calcimimetic agents on PTH and bone mineral biomarkers in hemodialysis patients with SHPT: a network meta-analysis

OBJECTIVE

Active vitamin D analogs and calcimimetic agents are primary drugs for patients with secondary hyperparathyroidism. Due to the different pharmacological mechanisms, they have different effects on the level of parathyroid hormone, serum calcium, phosphorus, and bone turnover biomarkers. This study aimed to evaluate the active vitamin D analogs and calcimimetic agents in hemodialysis patients with secondary hyperparathyroidism.

METHODS

We included randomized clinical trials of hemodialysis patients with secondary hyperparathyroidism, comparing active vitamin D analogs to calcimimetic agents or placebo/control. The primary outcome was the change of PTH level from baseline to end-up. The secondary outcome was the change in serum calcium, phosphorus, calcium-phosphorus product, and bone turnover biomarkers. A network meta-analysis method was applied to complete this study. The forest plots reflected statistical differences in the outcomes between active vitamin D analogs and calcimimetic agents. The SUCRA result presented the ranking of impact on the outcomes.

RESULTS

Twenty-one randomized clinical trials with 4653 patients were included in this network meta-analysis. Global and splitting-node inconsistencies provided no evidence of inconsistency in this study. There was no statistical difference between two active vitamin D analogs and three calcimimetic agents in the PTH, and phosphorus levels changed. Considering serum calcium level, compared with placebo, calcitriol (9.73, 3.09 to 16.38) and paricalcitol (9.74, 3.87 to 15.60) increase serum calcium. However, cinacalcet (- 1.94, - 3.72 to - 0.15) and etelcalcetide (- 7.80, - 11.80 to - 3.80) reduced the serum calcium, even a joint use of cinacalcet with active vitamin D analogs (- 5.83, - 9.73 to - 1.93). Three calcimimetic agents decreased calcium levels much more than calcitriol and paricalcitol. The same type of drugs was not distinct, with each one affecting the change in calcium level. Cinacalcet reduced calcium-phosphorus product much more than paricalcitol (- 3.66, - 6.72 to - 0.60). Evocalcet decreased calcium-phosphorus product more than cinacalcet (- 5.64, - 8.91 to - 2.37), calcitriol (- 9.36, - 14.81 to - 3.92), and paricalcitol (- 9.30, - 13.78 to - 4.82). Compared with paricalcitol, cinacalcet significantly increases the level of ALP (24.50, 23.05 to 25.95) and bALP (0.67, 0.03 to 1.31). The incidence of gastrointestinal disorders in cinacacet (29.35, 1.71 to 504.98) and etelcalcetide (20.92, 1.20 to 365.68) was notably higher than in paricalcitol. Etelcalcetide (0.71, 0.53 to 0.96) and evocalcet (0.46, 0.33 to 0.64) presented a lower rate of gastrointestinal disorders than cinacalcet. Cinacalcet ranked first in adverse gastrointestinal, nervous, and respiratory reactions.

CONCLUSION

The same kinds of agents perform similar efficacy on the level of PTH, serum calcium, phosphorus, and calcium-phosphorus product. Paricalcitol did not lead to more hypercalcemia than calcitriol. The calcium decrease induced by cinacalcet was not settled even by associating it with active vitamin D analogs. Cinacalcet and evocalcet were superior to calcitriol and paricacitol in reducing calcium-phosphorus product. Calcimimetics induced more gastrointestinal disorders than active vitamin D analogs, especially cinacalcet.

Pharmacokinetics, Pharmacodynamics, and Safety of Evocalcet (KHK7580), a Novel Calcimimetic Agent: An Open-Label, Single- and Multiple-Dose, Phase I Trial in Healthy Chinese Subjects

Purpose

This study explored the pharmacokinetics (PK), pharmacodynamics (PD), and safety of evocalcet (KHK7580), a new calcimimetic agent, in healthy Chinese subjects following single and multiple doses.

Methods

This was a single-center, open-label phase I trial conducted in China. The study started from the single-dose cohorts (1, 3, 6, 12 mg evocalcet, step-by-step administration) and proceeded to the multiple-dose cohort (6 mg evocalcet once daily for eight days). Blood and urine samples were collected at the designated time points for pharmacokinetic and pharmacodynamic analysis. Safety was evaluated by treatment-emergent adverse events (TEAEs), clinical laboratory tests, vital signs, electrocardiograms (ECGs), and ophthalmological examination.

Results

Among 42 enrolled subjects, eight in each single-dose cohort and 10 in multiple-dose cohort, 40 subjects completed the study. In single-dose cohorts, tmax was 1.00-2.00 h and declined biphasically. The mean t1/2 was 15.99-20.84 h. Evocalcet exposure in AUC0-inf, AUC0-t, and Cmax showed a dose-proportional increase. In the multiple-dose cohort, tmax was 2.00 h and declined biphasically after multiple administrations. The accumulation was negligible. Ctrough levels were similar across days and steady from 24 hours after the first administration. The mean t1/2 was 15.59 h. PD analysis showed that evocalcet decreased intact parathyroid hormone and corrected calcium levels in a dose-dependent manner. Seventeen (40.5%) subjects reported TEAEs. No serious or severe TEAE occurred.

Conclusion

In healthy Chinese subjects, evocalcet demonstrated dose-dependent PK and PD properties and was well-tolerated.

Comparison of the Oral Calcimimetics Evocalcet and Cinacalcet in East Asian Patients on Hemodialysis with Secondary Hyperparathyroidism

Introduction

Evocalcet is an oral calcimimetic agent with proven efficacy and safety in treating secondary hyperparathyroidism (SHPT) in Japanese patients on dialysis.

Methods

This randomized, double-blind, intrapatient dose-adjustment, parallel-group, international multicenter study compared the efficacy and safety of evocalcet versus cinacalcet for 52 weeks in East Asian hemodialysis patients with SHPT.

Results

In total, 203 and 200 patients were randomized to receive evocalcet or cinacalcet, respectively (overall, 70.1% had baseline intact parathyroid hormone (PTH) levels ≥500 pg/ml, with no between-group difference). Mean percentage changes in intact PTH levels from baseline were -34.7% and -30.2% in the evocalcet and cinacalcet groups at 52 weeks (between-group difference -4.4%, 95% confidence interval [CI] -13.1%, 4.3%, below the predefined 15% noninferiority margin). Overall, 67.3% and 58.7% of patients in the evocalcet and cinacalcet groups, respectively, achieved ≥30% decrease in intact PTH levels from baseline (between-group difference 8.6%; 95% CI -1.8%, 19.1%). No major safety concerns were observed. Gastrointestinal adverse events (AEs) were significantly less frequent with evocalcet compared with cinacalcet (33.5% vs. 50.5%, P = 0.001), whereas the incidence of hypocalcemia did not differ.

Conclusion

Evocalcet might be a better alternative to cinacalcet for East Asian patients on hemodialysis with SHPT.

Efficacy and Safety of Upacicalcet in Hemodialysis Patients with Secondary Hyperparathyroidism: A Randomized Placebo-Controlled Trial

BACKGROUND

Secondary hyperparathyroidism is a major complication of patients undergoing hemodialysis (HD). Upacicalcet, a new injectable calcimimetic, acts on calcium-sensing receptors to suppress parathyroid hormone (PTH) secretion. We examined the efficacy and safety of upacicalcet in patients with secondary hyperparathyroidism receiving HD.

METHODS

In this phase 3, double-blind, placebo-controlled study, we randomized Japanese patients undergoing HD with serum intact PTH (iPTH) concentrations >240 pg/ml and corrected calcium concentrations ≥8.4 mg/dl. Either upacicalcet or placebo was administered after each HD session for 24 weeks. The primary outcome was the percentage of participants achieving the target mean serum iPTH concentration (60-240 pg/ml) at weeks 22-24.

RESULTS

A total of 103 participants received upacicalcet, and 50 participants received the placebo. The percentage of participants achieving mean serum iPTH concentrations of 60-240 pg/ml during the evaluation period was 67% (69/103) in the upacicalcet group and 8% (4/50) in the placebo group. The difference between the two groups was 59% (95% confidence interval, 48% to 71%). Upacicalcet also decreased serum fibroblast growth factor-23, bone-specific alkaline phosphatase, total type 1 procollagen-N-propeptide, and tartrate-resistant acid phosphatase-5b concentrations. Adverse events were reported in 85% (88/103) and 72% (36/50) participants in the upacicalcet and placebo groups, respectively. The incidence of upper gastrointestinal adverse events, such as nausea and vomiting, was similar between the two groups. Serum corrected calcium concentrations <7.5 mg/dl were observed in 2% of participants in the upacicalcet group and no participants in the placebo group.

CONCLUSIONS

Upacicalcet, a novel injectable calcimimetic, is effective and safe for secondary hyperparathyroidism patients receiving HD.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Phase 3 Study of SK-1403, NCT03801980 .

Role of Chronic Kidney Disease (CKD)-Mineral and Bone Disorder (MBD) in the Pathogenesis of Cardiovascular Disease in CKD

Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD). Multiple factors account for the increased incidence of cardiovascular morbidity and mortality in patients with CKD. Traditional risk factors for atherosclerosis and arteriosclerosis, including age, hypertension, dyslipidemia, diabetes mellitus, and smoking, are also risk factors for CKD. Non-traditional risk factors specific for CKD are also involved in CVD pathogenesis in patients with CKD. Recently, CKD-mineral and bone disorder (CKD-MBD) has emerged as a key player in CVD pathogenesis in the context of CKD. CKD-MBD manifests as hypocalcemia and hyperphosphatemia in the later stages of CKD; however, it initially develops much earlier in disease course. The initial step in CKD-MBD involves decreased phosphate excretion in the urine, followed by increased circulating concentrations of fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH), which increase urinary phosphate excretion. Simultaneously, the serum calcitriol concentration decreases as a result of FGF23 elevation. Importantly, FGF23 and PTH cause left ventricular hypertrophy, arrhythmia, and cardiovascular calcification. More recently, calciprotein particles, which are nanoparticles composed of calcium, phosphate, and fetuin-A, among other components, have been reported to cause inflammation, cardiovascular calcification, and other clinically relevant outcomes. CKD-MBD has become one of the critical therapeutic targets for the prevention of cardiovascular events and is another link between cardiology and nephrology. In this review, we describe the role of CKD-MBD in the pathogenesis of cardiovascular disorders and present the current treatment strategies for CKD-MBD.

Effects of evocalcet on parathyroid calcium-sensing receptor and vitamin D receptor expression in uremic rats

Little is known about the effect of the recently developed calcimimetic evocalcet (Evo) on parathyroid calcium-sensing receptor (CaSR) and vitamin D receptor (VDR) expression. We examined the effects of Evo and cinacalcet (Cina) on CaSR and VDR expression in 5/6 nephrectomized Sprague-Dawley rats fed a high-phosphorus diet for 4 weeks to develop secondary hyperparathyroidism (SHPT). These uremic rats were divided into 4 groups-baseline control (Nx4W) and groups with additional treatment with either the Vehicle, Evo, or Cina for 2 weeks; normal rats were used as normal controls (NC). Blood parameters and parathyroid tissue were analyzed. CaSR and VDR expression levels were determined using immunohistochemistry. The degree of kidney injury and hyperphosphatemia was similar in the uremic groups (Nx4W, Vehicle, Cina, and Evo). Serum parathyroid hormone levels were significantly higher in the Nx4W and Vehicle groups than in the NC group. This increase was significantly suppressed in the Cina and Evo groups compared with that in the Vehicle group. Serum calcium levels were significantly and equally lower in the Cina and Evo groups relative to those in the Vehicle group. CaSR expression was significantly lower in the Nx4W and Vehicle groups than in the NC group. This downregulation was of an equally lesser magnitude in the Cina and Evo groups. A similar trend was observed for VDR expression. These results indicate that Evo and Cina treatment can increase parathyroid CaSR and VDR expression in uremic rats with SHPT, which could provide better control of mineral and bone disorder markers.

Neuroendocrine Parathyroid Tumors: Quality of Life in Patients with Primary Hyperparathyroidism

Tumors of the parathyroid glands, when associated with PTH (parathyroid hormone) excess, display a large area of complications; in addition to the classical clinical picture of primary hyperparathyroidism (PHP), a complex panel of other symptoms/signs can be identified, including memory and cognitive impairment, chronic asthenia/fatigue, reduced muscle functionality, depressive mood, non-specific bone pain, and loss of sleep quality. The perception of quality of life (QoL) can be supplementarily enhanced by their progressive onset, which makes many patients not be fully aware of them. Their improvement was reported very early after parathyroidectomy (PTx), yet the level of statistical evidence does not qualify these non-classical elements as standalone indications for PTx. Our objective is introducing an up-to-date on QoL scores with regards to the patients diagnosed with PHP, particularly taking into consideration PHP management from baseline to post-operatory outcome, including in cases with multiple endocrine neoplasia. This is a narrative review of literature. We revised full-length papers published in English through PubMed research conducted between January 2018 and May 2023 by using the key words "quality of life" and "primary hyperparathyroidism". We particularly looked at data on self-reported QoL (through questionnaires). We excluded from the search the studies focused on non-PTH related hypercalcemia, secondary, and/or renal/tertiary hyperparathyroidism, and vitamin D supplementation. Overall, we identified 76 papers and selected for the final analysis 16 original studies on QoL and PHP (a total of 1327 subjects diagnosed with syndromic and non-syndromic PHP). The studies with the largest number of individuals were of 92, 104, 110, 134, 159, as well as 191. A few cohorts (n = 5) were of small size (between 20 and 40 patients in each of them). Concerning the study design, except for 2 papers, all the mentioned studies provided longitudinal information, particularly the timeframe from baseline (before PTx) and after surgery. The post-operatory follow-up was of 3-6 months, but mostly between 1 and 3 years (maximum a decade of surveillance). The age of the patients varies between medians of 56, 62, 64, and 68 years. Most frequent questionnaires were SF-36, PHPQoL, and PAS. Despite not being unanimously similar, an overall reduced score of QoL in patients with PHP versus controls was registered, as well as general improvement following PTx. Variations of QoL results might have a multifactorial background from different comorbidities, studied populations, technical aspects of collecting the data, etc. QoL scores in PHP represents a complex heterogeneous picture, from their correlation with clinical features and lab assays (e.g., the level of serum calcium), the associated comorbidities (such as multiple endocrine neoplasia syndromes), up to the assessment of the QoL improvement after parathyroidectomy (PTx). While current studies do not unanimously agree on each QoL domain, the assessment of QoL might represent a supplementary argument to consider when deciding for PTx, especially in asymptomatic cases and in patients who do not fit into well-known categories of surgery candidates, according to current guidelines, thus assessing QoL in PHP is part of a current research gap. QoL evaluation in PHP remains an open issue, towards which awareness should be cultivated by both endocrinologists and surgeons. The introduction of a routine evaluation of the QoL scores in patients, as well as the selection of the most appropriate questionnaire(s), represents an open chapter thus awareness in mandatory.

Treatment for secondary hyperparathyroidism focusing on parathyroidectomy

Secondary hyperparathyroidism (SHPT) is a major problem for patients with chronic kidney disease and can cause many complications, including osteodystrophy, fractures, and cardiovascular diseases. Treatment for SHPT has changed radically with the advent of calcimimetics; however, parathyroidectomy (PTx) remains one of the most important treatments. For successful PTx, removing all parathyroid glands (PTGs) without complications is essential to prevent persistent or recurrent SHPT. Preoperative imaging studies for the localization of PTGs, such as ultrasonography, computed tomography, and 99mTc-Sestamibi scintigraphy, and intraoperative evaluation methods to confirm the removal of all PTGs, including, intraoperative intact parathyroid hormone monitoring and frozen section diagnosis, are useful. Functional and anatomical preservation of the recurrent laryngeal nerves can be confirmed via intraoperative nerve monitoring. Total or subtotal PTx with or without transcervical thymectomy and autotransplantation can also be performed. Appropriate operative methods for PTx should be selected according to the patients' need for kidney transplantation. In the case of persistent or recurrent SHPT after the initial PTx, localization of the causative PTGs with autotransplantation is challenging as causative PTGs can exist in the neck, mediastinum, or autotransplanted areas. Additionally, the efficacy and cost-effectiveness of calcimimetics and PTx are increasingly being discussed. In this review, medical and surgical treatments for SHPT are described.

Effect of early dose increase of evocalcet for intractable hypercalcemia caused by parathyroid carcinoma

Summary

Hypercalcemia due to parathyroid carcinoma (PC) is safely and quickly controlled with rapidly increasing evocalcet doses. Most parathyroid carcinomas are detected because of hypercalcemia due to primary hyperparathyroidism (PHPT). Hypercalcemia becomes more severe in patients with PC than those with parathyroid adenoma or hyperplasia. Hypercalcemia often causes renal dysfunction, gastrointestinal symptoms, and psychiatric symptoms. Consequently, the serum calcium level needs to be promptly corrected. Here, we report a case of PC with remarkably persistent hypercalcemia, which we safely and quickly controlled with rapidly increasing evocalcet doses. A 77-year-old female presented with renal dysfunction. Her serum calcium (Ca) and intact parathyroid hormone serum levels were 13.9 mg/dL and 1.074 pg/mL, respectively. Her renal function worsened because of hypercalcemia due to PHPT. Technetium-99 m methoxy-isobutyl-isonitrile parathyroid scintigraphic examination revealed an accumulation below the right thyroid lobe. CT examination showed a 35-mm mass. Hypercalcemia needed to be immediately corrected because of the patient's worsening renal function. Evocalcet treatment at a gradually increasing dose of up to 20 mg over 3 weeks allowed her serum Ca level to be maintained below 11 mg/dL. Only mild nausea was observed at the beginning of the treatment. The mass was suspected as PC because the hypercalcemia was refractory to high-dose evocalcet. The patient was treated with parathyroidectomy and ipsilateral thyroidectomy. PC was diagnosed based on the pathological findings of capsular and venous invasion. The patient's renal function improved and surgery could be safely performed by promptly correcting hypercalcemia.

Learning points

Hypercalcemia due to parathyroid carcinoma (PC) is often more severe than that caused by parathyroid adenoma or hyperplasia. PC is a rare disease, but it should be considered if the patient has intractable hypercalcemia due to primary hyperparathyroidism (PHPT). Evocalcet, which is used to treat hypercalcemia due to PHPT, does not interact with P450 (CYP) and causes few side effects. Complications, including renal dysfunction, were improved and the surgery could be safely performed by promptly correcting hypercalcemia. PC has a high recurrence rate. En-block excision is necessary when PC is suspected.

Predictive factors requiring high-dose evocalcet in hemodialysis patients with secondary hyperparathyroidism

The dosage of evocalcet required to control serum parathyroid hormone (PTH) levels varies among secondary hyperparathyroidism (SHPT) patients. This post hoc analysis evaluated the dose-dependent efficacy of evocalcet on serum intact PTH (iPTH) levels, corrected calcium (Ca) and phosphate (P) levels, and safety, in an evaluation period (week 28 to week 30) by stratifying the previous phase 3 data with the final evocalcet dosages (low 1-2 mg [131 patients], medium 3-4 mg [90 patients], high 5-8 mg [92 patients]), and identified pre-treatment patient characteristics predicting the use of higher final evocalcet dosages via univariate and multivariate logistic regression models. At the end of the study at week 30, the median serum iPTH level was higher and the achievement ratio for the target range of Japanese Society for Dialysis Therapy (60-240 pg/mL) was lower in the final high-dose subgroup (216 pg/mL and 58%, respectively) than in the other subgroups (low: 149 pg/mL and 79%; medium: 149 pg/mL and 73%, respectively). Among the three subgroups, the mean serum corrected Ca and P levels demonstrated similar trends, and similar ratio of patients achieved the target range (corrected Ca, 8.4-10 mg/dL; P, 3.5-6.0 mg/dL) from week 28 to week 30. No dose-dependent safety concerns were identified. Younger age, prior cinacalcet use, higher serum levels of iPTH and corrected Ca, procollagen type 1 N-terminal propeptide, intact fibroblast growth factor-23, and larger maximum parathyroid gland volume were significantly associated with final high-dose evocalcet (p < 0.05 in all cases). Patients requiring final high-dose evocalcet had pre-treatment characteristics indicating severe SHPT, leading to a lower final achievement rate for the target PTH levels of Japanese Society for Dialysis Therapy. Therefore, the early initiation of evocalcet treatment for SHPT is critical. Trial registration: This trial was registered as follows: ClinicalTrials.gov: NCT02549391 and JAPIC: JapicCTI-153013.

Activation of Calcium-Sensing Receptor in the Area Postrema Inhibits Food Intake via Glutamatergic and GABAergic Signaling Pathways

SCOPE

A high-protein diet has become a popular way to lose weight. Calcium-sensing receptor (CaSR) is activated by amino acids in addition to calcium ions. CaSR shows dense expression in the area postrema (AP), which participates in feeding regulation. The effect of CaSR in the AP on food intake and the potential mechanism involved is investigated.

METHODS AND RESULTS

Male C57BL/6 mice are used to observe the effect of R568 (agonist of CaSR) on food intake. Enzyme-linked immunosorbent assay, immunofluorescence staining, and chemogenetics are used to explore the neural signaling involved. CaSR activation in the AP inhibited acute feeding; R568 increases the content of glutamate and γ-aminobutyric acid (GABA) in the AP, whereas only glutamatergic neurons mediate the effect of R568. GABA-A receptor and ionic glutamate receptor (N-methyl-D-aspartate receptor [NMDAR]) in the paraventricular nucleus of hypothalamus (PVN) are involved in the effect of R568. Promotion of oxytocin (OT) synthesis in the PVN also participates in the effect of R568, and this mechanism is mediated by NMDAR in the PVN.

CONCLUSION

CaSR activation in the AP suppresses feeding, and AP-PVN glutamatergic and GABAergic signaling pathways are involved.

Dialysate calcium, alfacalcidol, and clinical outcomes: A post-hoc analysis of the J-DAVID trial

The selection of dialysate calcium concentration (D-Ca) is still controversial among chronic hemodialysis (HD) regimens. We examined the trajectories of CKD MBD parameters among the J-DAVID trial participants to see the effect of D-Ca and alfacalcidol. The trial was an open-label randomized clinical trial including 976 HD patients with intact PTH of 180 pg/mL or lower which compared the users of vitamin D receptor activator (oral alfacalcidol) and non-users over a median of 4 years. The main D-Ca used at baseline were 3.0 mEq/L in 70% and 2.5 mEq/L in 25%, respectively. The primary endpoint was the composite of fatal and non-fatal cardiovascular events and the secondary endpoint was all-cause mortality. Multivariable Cox proportional hazard regression analyses in which D-Ca was included as a possible effect modifier and serum laboratory data as time-varying covariates showed no significant effect modification for composite cardiovascular events or all-cause mortality. This post hoc analysis showed that the effects of alfacalcidol on cardiovascular outcomes were not significantly modified by D-Ca.

First-in-Human Phase I Study of the Novel Injectable Calcimimetic Agent Upacicalcet in Healthy Adult Japanese Participants

Background and Objective

Upacicalcet sodium hydrate is a novel small-molecule calcimimetic and has potential as a therapeutic agent for secondary hyperparathyroidism. We assessed the pharmacokinetics, pharmacodynamics, safety, and tolerability of a single intravenous dose of upacicalcet in Japanese healthy adults.

Method

This was a single-center, double-blinded, randomized, placebo-controlled, dose-escalation study. For each cohort, eight subjects were randomly assigned at a ratio of 3:1 to receive a single injection of placebo or upacicalcet 0.01, 0.1, 1.0, or 2.5 mg.

Result

The plasma concentration of upacicalcet increased in a dose-dependent manner. Upacicalcet rapidly disappeared from plasma after administration. The half-life of upacicalcet was approximately 1–2 h. The major excretion route of upacicalcet was via urine. Serum intact parathyroid hormone decreased in accordance with the upacicalcet dose, from the lowest dose of 0.01 mg. Gastrointestinal disorders occurred in one patient in the 1.0 mg group and in five patients in the 2.5 mg group. All adverse events were nonserious, and no symptomatic hypocalcemia occurred.

Conclusion

This study showed that upacicalcet acted as a calcimimetic and was excreted in the urine unchanged with little metabolism. Moreover, upacicalcet is a small molecule and has a small volume of distribution. In addition, less than 50% of upacicalcet binds to human plasma proteins. These findings suggest that upacicalcet administered to patients undergoing hemodialysis might be expected to have a long excretion period and sustained pharmacological effect.

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).

A Systematic Review and Meta-analysis of Efficacy and Safety of Calcimimetic Agents in the Treatment of Secondary Hyperparathyroidism in Patients with Chronic Kidney Disease

BACKGROUND

Some reports have pointed out that calcimimetics agents are effective in the treatment of secondary hyperparathyroidism (SHPT) in chronic kidney disease (CKD) patients, but there is no detailed description of the advantages and disadvantages of calcimimetics agents of SHPT in CKD patients. We tried to pool the published data to verify the effectiveness of calcimimetics agents and to compare the advantages and disadvantages of cinacalcet compared with control in the treatment of SHPT in CKD patients.

METHODS

We included eligible studies of published papers from January 1st, 2000 to December 31st, 2020 in Medline, Pubmed and Web of science databases, and the data were extracted for this meta-analysis.

RESULTS

Twenty-seven studies were eligible, and all the included studies were randomized controlled trials (RCT) including patients treated with long-term dialysis. The results indicated that calcimimetic agents can reduce the parathyroid hormone (PTH, pg/ml) level (WMD = -178.22, 95% CI: -238.57, -117.86, P < 0.00001), calcium (Ca, mg/dl) level (WMD = -0.71, 95% CI: -0.86, -0.55, P < 0.00001), phosphorus (P, mg/dl) level (WMD = -0.32, 95% CI: -0.55, -0.08, P = 0.008), calcium-phosphorus product level (WMD = -7.73, 95% CI: -9.64, -5.82, P < 0.00001). Calcimimetic agents increased the bone alkaline phosphatase (BSAP, ng/ml) levels and rate of achieving target PTH, and reduced osteocalcin levels and the rate of parathyroidectomy. Calcimimetic agents increased the total adverse events' rate, the rate of hypocalcemia and gastrointestinal side effects (nausea, vomiting, abdominal pain and diarrhea), but there was no significant difference in serious adverse events between the calcimimetic agent group and control group.

CONCLUSION

Calcimimetic agents can reduce the PTH level, Ca level, P level, calcium-phosphorus product level and do not increase serious adverse events.

Activation of the Calcium Receptor by Calcimimetic Agents Is Preserved Despite Modest Attenuating Effects of Hyperphosphatemia

BACKGROUND

Phosphorus levels in the range seen clinically among patients undergoing dialysis have been reported to attenuate calcium receptor activation and modify parathyroid hormone (PTH) release from isolated parathyroid glands in vitro. Some clinicians and providers of dialysis thus have suggested that calcimimetic agents are ineffective and should not be used to manage secondary hyperparathyroidism among those undergoing dialysis when serum phosphorus concentrations exceed certain threshold levels.

METHODS

To determine whether hyperphosphatemia diminishes the therapeutic response to calcimimetic agents, we used data from large clinical trials to analyze the effects of etelcalcetide and cinacalcet to lower plasma PTH levels in individuals on hemodialysis who had secondary hyperparathyroidism and varying degrees of hyperphosphatemia.

RESULTS

Plasma PTH levels declined progressively during 26 weeks of treatment with either etelcalcetide or cinacalcet without regard to the degree of hyperphosphatemia at baseline. However, with each calcimimetic agent, the decreases in PTH from baseline were less at each interval of follow-up during the trials among participants with serum phosphorus levels above one of three prespecified threshold values compared with those with serum phosphorus levels below these thresholds.

CONCLUSIONS

These in vivo findings are the first in humans to support the idea that hyperphosphatemia attenuates calcium receptor activation by calcium ions and by calcimimetic agents. The effect of hyperphosphatemia on the responsiveness to calcimimetic agents appears relatively modest, however, and unlikely to be significant therapeutically. The efficacy of treatment with calcimimetic agents for lowering plasma PTH levels among those with secondary hyperparathyroidism remains robust despite substantial elevations in serum phosphorus.

Advances in the treatment of secondary and tertiary hyperparathyroidism

Secondary hyperparathyroidism (SHPT) and tertiary hyperparathyroidism (THPT) are common and complicated clinical endocrine diseases. The parathyroid glands maintain endocrine homeostasis by secreting parathyroid hormone to regulate blood calcium levels. However, structural alterations to multiple organs and systems occur throughout the body due to hyperactivity disorder in SHPT and THPT. This not only decreases the patients' quality of life, but also affects mortality. Since current treatments for these diseases remains unclear, we aimed to develop a comprehensive review of advances in the treatment of SHPT and THPT according to the latest relevant researches.

Efficacy of Evocalcet in Previously Cinacalcet-Treated Secondary Hyperparathyroidism Patients

Introduction

Evocalcet is a recently approved calcimimetic agent for secondary hyperparathyroidism (SHPT). In this study, the efficacy and safety of once-daily oral evocalcet were evaluated in patients without prior cinacalcet use (nonusers) and previously treated patients (users).

Methods

This post hoc analysis of a previous phase III head-to-head comparison study included SHPT patients treated with evocalcet with or without prior cinacalcet use. Endpoints included trends in the median intact and whole parathyroid hormone (PTH), mean corrected calcium, phosphate, and bone metabolic markers, and whole-to-intact PTH ratios throughout the 30-week study period; proportions of patients achieving target intact PTH, corrected calcium, and phosphate at weeks 28 to 30; and adverse drug reactions (ADRs).

Results

This study included 127 nonusers and 190 users with significant differences in age; duration of dialysis; use of intravenous vitamin D receptor activators; levels of intact PTH, corrected calcium, tartrate-resistant acid phosphatase 5b, procollagen type 1 N-terminal-propeptide; and largest parathyroid gland volume (P < 0.05 for all characteristics) between 2 groups at baseline. Users required higher evocalcet dosages than nonusers. Similar efficacy results were found in the 2 groups except for a significantly higher proportion of nonusers achieving the intact PTH target (81.6% vs 67.1%, difference [95% confidence interval], −14.5% [−24.59, −3.34]), and a significant reduction in largest parathyroid gland volume from week 0 to week 30 (−120.6 [567.2] mm³, P = 0.043). No difference was found in ADRs between the 2 groups.

Conclusion

Treatment with evocalcet is effective and safe irrespective of prior cinacalcet treatment in SHPT patients.

A case of a hemodialysis patient with secondary hyperparathyroidism who was resistant to etelcalcetide treatment but not to cinacalcet hydrochloride

Although both cinacalcet and etelcalcetide are calcimimetics that directly inhibit parathyroid hormone (PTH) secretion by activating the calcium (Ca)-sensing receptor (CaSR), their binding sites are different. We report a first case of a hemodialysis (HD) patient with secondary hyperparathyroidism (SHPT), in whom cinacalcet, but not etelcalcetide, could reduce serum intact PTH (i-PTH) levels. A HD patient received total parathyroidectomy (PTx) with auto-transplantation 16 years earlier. Due to SHPT relapse, cinacalcet was started at 7 years after PTx. His i-PTH levels had been controlled with both 75–100 mg of cinacalcet and 4.5 μg/week of calcitriol for a year before switching from cinacalcet to etelcalcetide. At 1 month following the switch, his serum i-PTH level increased to 716 pg/mL. The dose of etelcalcetide was gradually increased and finally reached the maximal dose of 45 mg/week. Because even the maximal dose of etelcalcetide for > 4 months did not reduce his serum i-PTH levels to < 700 pg/mL, etelcalcetide was switched to 50 mg/day of cinacalcet, which reduced the levels to 208 pg/mL at 2 months after the switch. Genomic sequencing test using whole blood revealed no mutation in the portion including Cys 482 of CaSR gene. The patient was resistant to etelcalcetide treatment but not to cinacalcet, suggesting the possibility that the enlarged parathyroid gland has some change in the portion including Cys 482 in the CaSR gene. Therefore, considering the possibility of etelcalcetide resistance during SHPT treatment should be kept in mind.

Coexistence of papillary thyroid carcinoma in secondary hyperparathyroidism

Background

The coexistence of primary hyperparathyroidism and papillary thyroid carcinoma (PTC) is common and may be associative with more aggressive PTC, with higher rates of extrathyroidal extension and multicentricity. However, it is unclear whether secondary hyperparathyroidism (SHPT) is associated with more invasive PTC in terms of morbidity, tumor pathological characteristics, and prognosis. The aim of this study was to evaluate the rate and tumor characteristics of PTC in patients with SHPT.

Methods

A total of 531 patients diagnosed with SHPT who underwent surgery from August 2013 to December 2018 at the First Affiliated Hospital of Zhejiang University were evaluated retrospectively. Patient demographics, surgical records, and follow-up information were recorded and analyzed. Control subjects were matched to the enrolled patients in a 1:4 ratio in terms of age, sex and pathological subtype.

Results

Among the 531 patients with SHPT who underwent surgery, 34 had coexisting PTC and PTC + SHPT (6.4%). The mean tumor diameter in the PTC + SHPT group was smaller than that in the PTC group (5.57 mm vs 9.00 mm, p < 0.001). The proportion of papillary thyroid micro-carcinoma in the PTC + SHPT group was significantly higher than that in the PTC group (29 [85.29%] vs. 86[63.24%], p = 0.014). There were no statistically significant differences between groups in terms of tumor multicentricity (15 [44.12%] vs 39 [28.68%], p = 0.066), tumor bilaterality (9 [26.47%] vs. 29 [21.32%], p = 0.499), tumor extrathyroidal extension (2 [5.88%] vs. 19 [13.97%], p = 0.255), or lymph node (LN) metastasis rate (12 [35.29%] vs. 49 [36.03%], p = 1.000). However, the PTC + SHPT and PTC groups were significantly different in terms of contralateral thyroidectomy (10 [29.41%] vs. 70 [51.47%], p = 0.023) and lymph node dissection (22 [64.71%] vs. 125 [91.91%], p < 0.001).There was no significant difference between the PTC + SHPT and PTC groups in terms of prognostic staging (33 [97.06%] vs. 122 [89.71%], p = 0.309) or recurrence (mean follow-up time: 36 months vs. 39 months, p = 0.33).

Conclusions

The prevalence of PTC is high in patients with SHPT; compared with PTC in the general population, most papillary thyroid carcinomas with SHPT are occult thyroid carcinomas and present no significant difference in terms of tumor pathological features and prognostic staging. It is necessary for surgeons to perform more adequate preoperative examination and be more careful during surgery to avoid missing the coexistence of PTC in patients with SHPT.

Bone responsiveness to parathyroid hormone is negatively associated with parathyroid hormone-lowering drug use in patients undergoing hemodialysis: a cross-sectional study

BACKGROUND

Parathyroid hormone (PTH) acts on bone to indirectly increase the number and activity of osteoclasts. Thus, PTH has a stimulatory effect on bone resorption and upregulates bone turnover. However, the responsiveness of bone to PTH varies widely among patients receiving dialysis. In fact, relative to the serum PTH level, the level of serum tartrate-resistant acid phosphatase-5b (TRACP-5b), a bone resorption marker derived from osteoclasts, varies as well. This study aimed to examine factors related to bone responsiveness to PTH in patients undergoing chronic hemodialysis (HD).

METHODS

This study included patients receiving chronic HD in Kawasaki Municipal Tama Hospital (Kanagawa, Japan) and Yonaha Medical Clinic (Okinawa, Japan) and excluded patients who received HD for less than 6 months, those who received a combination of HD and peritoneal dialysis, and those who had cancer bone metastases or myeloma. The TRACP-5b/intact PTH (iPTH) ratio was created as an index of bone responsiveness to PTH, categorized into tertiles (low, medium, and high), and a cross-sectional study was conducted. P < 0.05 indicated statistically significant differences.

RESULTS

One hundred and six patients were analyzed. Age (P = 0.010), body mass index (BMI) (P = 0.003), use of calcium-sensing receptor (CaSR) agonists (P = 0.008), use of vitamin D receptor activators (VDRAs) (P = 0.012), plasma iPTH level (P < 0.001), serum 1,25(OH)₂D level (P = 0.003), and serum TRACP-5b level (P < 0.001) were significantly different among the three categories. In the single linear regression analysis, age (P = 0.016), corrected serum calcium level (P = 0.007), and ln [1,25(OH)₂D] (P = 0.044) showed a significant positive correlation with ln [TRACP-5b/iPTH], whereas BMI (P = 0.026), use of CaSR agonists (P = 0.001), use of VDRAs (P = 0.009), and serum phosphorus level (P = 0.018) showed a significant negative correlation. Upon conducting multiple linear regression analysis incorporating significant variables in the single linear regression analysis, a significant negative correlation was observed between the TRACP-5b/iPTH ratio and intravenous administration of a CaSR agonist (etelcalcetide) and/or a VDRA (calcitriol or maxacalcitol) in all the adjusted models.

CONCLUSIONS

Bone responsiveness to PTH is negatively correlated with the intravenous administration of a CaSR agonist and/or a VDRA in patients undergoing chronic HD.

Association of CYP3A5 polymorphisms and parathyroid hormone with blood level of tacrolimus in patients with end-stage renal disease

Because tacrolimus is predominantly metabolized by CYP3A, the blood concentration/dose (C/D) ratio is affected by CYP3A5 polymorphism. Parathyroid hormone (PTH) expression increases in secondary hyperparathyroidism, which is frequently associated with end‐stage renal disease. Recently, PTH has been shown to downregulate CYP3A expression at mRNA level. In this study, we examined the influence of CYP3A5 polymorphism on and association of serum intact‐PTH (iPTH) level with blood tacrolimus concentration in patients with end‐stage renal disease just before kidney transplantation. Forty‐eight patients who satisfied the selection criteria were analyzed. Subjects were classified into two phenotype subgroups: CYP3A5 expressor (CYP3A5*1/*1 and *1/*3; n = 15) and CYP3A5 nonexpressor (CYP3A5*3/*3; n = 33). The blood tacrolimus C/D (per body weight) ratio was significantly lower in CYP3A5 expressors than that in CYP3A5 nonexpressors. A significant positive correlation was found between tacrolimus C/D and iPTH concentrations (r = 0.305, p = 0.035), and the correlation coefficient was higher after excluding 20 patients co‐administered CYP3A inhibitor or inducer (r = 0.428, p = 0.023). A multiple logistic regression analysis by stepwise selection identified CYP3A5 polymorphism and serum iPTH level as significant factors associated with tacrolimus C/D. These results may suggest the importance of dose design considering not only the CYP3A5 phenotype but also serum iPTH level when using tacrolimus in patients who undergo renal transplantation.

Old and New Drugs for the Management of Bone Disorders in CKD

Disturbances in mineral and bone metabolism are common in patients with chronic kidney disease (CKD), especially those undergoing dialysis. Renal osteodystrophy, which describes an alteration of bone morphology, is an important component of this systemic disorder and may explain the elevated risk of fracture which adversely affects morbidity and mortality. The most common form of renal osteodystrophy is high-turnover bone disease (osteitis fibrosa), which is induced by secondary hyperparathyroidism (SHPT). During the past decade, there has been considerable advances in the management of SHPT, with the introduction of the calcimimetic agents, the optimized use of nutritional and active vitamin D, and the accumulated experience with surgical parathyroidectomy. Studies supported that these advances could translate into improvement of renal bone disease and fracture prevention, as well as decreasing the risk of cardiovascular events and mortality. In this review, we summarize the available clinical evidence on the effect of old and new drugs on bone disorders in patients with CKD.

Therapeutic Opportunities of Targeting Allosteric Binding Sites on the Calcium-Sensing Receptor

The CaSR is a class C G protein-coupled receptor (GPCR) that acts as a multimodal chemosensor to maintain diverse homeostatic functions. The CaSR is a clinical therapeutic target in hyperparathyroidism and has emerged as a putative target in several other diseases. These include hyper- and hypocalcaemia caused either by mutations in the CASR gene or in genes that regulate CaSR signaling and expression, and more recently in asthma. The development of CaSR-targeting drugs is complicated by the fact that the CaSR possesses many different binding sites for endogenous and exogenous agonists and allosteric modulators. Binding sites for endogenous and exogenous ligands are located throughout the large CaSR protein and are interconnected in ways that we do not yet fully understand. This review summarizes our current understanding of CaSR physiology, signaling, and structure and how the many different binding sites of the CaSR may be targeted to treat disease.

The effect of evocalcet on vagus nerve activity of the gastrointestinal tract in miniature pigs

Evocalcet is a novel calcimimetic agent with fewer gastrointestinal (GI) adverse effects compared to cinacalcet. Although it is thought that cinacalcet induces GI side effects through the direct stimulation of the calcium receptor (CaR) expressed in the GI tract, the differences in the direct stimulatory effects of these two drugs on the GI tract have not been reported. In this study, we analyzed the difference in the GI effects of these two calcimimetic agents using miniature pigs by detecting vagus nerve stimulation after oral administration of the agents. Although cinacalcet induced vomiting in miniature pigs, evocalcet never induced emetic symptoms. A significant increase in the vagus nerve action potentials was observed after the administration of cinacalcet. Although the increase of that after the administration of evocalcet was mild and not significant in comparison to that in the vehicle group, it was not significantly different from the vagus nerve action potentials after cinacalcet treatment.

The risk of medically uncontrolled secondary hyperparathyroidism depends on parathyroid hormone levels at haemodialysis initiation

BACKGROUND

Optimal parathyroid hormone (PTH) control during non-dialysis chronic kidney disease (ND-CKD) might decrease the subsequent risk of parathyroid hyperplasia and uncontrolled secondary hyperparathyroidism (SHPT) on dialysis. However, the evidence for recommending PTH targets and therapeutic strategies is weak for ND-CKD. We evaluated the patient characteristics, treatment patterns and PTH control over the first year of haemodialysis (HD) by PTH prior to HD initiation.

METHODS

We studied 5683 incident HD patients from 21 countries in Dialysis Outcomes and Practice Patterns Study Phases 4-6 (2009-18). We stratified by PTH measured immediately prior to HD initiation and reported the monthly prescription prevalence of active vitamin D and calcimimetics over the first year of HD and risk of PTH >600 pg/mL after 9-12 months on HD.

RESULTS

The 16% of patients with PTH >600 pg/mL prior to HD initiation were more likely to be prescribed active vitamin D and calcimimetics during the first year of HD. The prevalence of PTH >600 pg/mL 9-12 months after start of HD was greater for patients who initiated HD with PTH >600 (29%) versus 150-300 (7%) pg/mL (adjusted risk difference: 19%; 95% confidence interval : 15%, 23%). The patients with sustained PTH >600 pg/mL after 9-12 months on HD were younger, more likely to be black, and had higher serum phosphorus and estimated glomerular filtration rates at HD initiation.

CONCLUSIONS

Increased PTH before HD start predicted a higher PTH level 9-12 months later, despite greater use of active vitamin D and calcimimetics. More targeted PTH control during ND-CKD may influence outcomes during HD, raising the need for PTH target guidelines in these patients.

Efficacy and safety of evocalcet in treatment of secondary hyperparathyroidism in chronic kidney disease on hemodialysis patients: A protocol for a systematic review and meta-analysis

BACKGROUND

Secondary hyperparathyroidism (SHPT) have been associated with poor health outcomes in hemodialysis patients. The cinacalcet has popularized in clinic which has efficacy but more adverse events; the novel oral calcimimetic agents evocalcet has appeared in recent years. However, it is currently unknown whether evocalcet produces more beneficial effects and fewer adverse events in patients with SHPT. The aim of this systematic review is to estimate the safety and efficacy of evocacelt.

METHODS

Only randomized controlled trials (RCT) will be included in MEDLINE, EMBASE, the Cochrane Register of Controlled Trials, and PUBMED from July 2010 to July 2020. Two reviewers will screen, select studies, extract data, and assess quality independently. The methodological quality including the risk of bias of the included studies will be evaluated using a modified assessment form, which is based on Cochrane assessment tool. Review Manager 5.3 software will be used for heterogeneity assessment, generating funnel-plots, data synthesis, subgroup analysis, and sensitivity analysis. We will use GRADE system to evaluate the quality of our evidence.

RESULTS

We will provide some more practical and targeted results investigating the effect and safety of evocalcet for SHPT on hemodialysis in the current meta-analysis.

CONCLUSION

The stronger evidence about evocalcet effect and safety will be provided for clinicians and policymakers.

ETHICS AND DISSEMINATION

Ethical approval will be unnecessary because the data being included in this systematic review come from published literature and there will be no concerns regarding privacy. Findings of this research will be disseminated in a peer-reviewed journal or conference presentations.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/N59RB.

Development of evocalcet for unmet needs among calcimimetic agents

INTRODUCTION

The calcium-sensing receptor is an important treatment target for secondary hyperparathyroidism (SHPT) in patients undergoing dialysis. In addition to vitamin D receptor activator, cinacalcet has recently been widely used for SHPT management, and the significant suppression of parathyroid hormone (PTH) with better control of serum calcium and phosphorus has been reported. However, low adherence and insufficient dose escalation mainly due to frequent gastrointestinal adverse events, still remain as major issues. To overcome these unmet needs, we have developed a new oral calcimimetic agent evocalcet, which has recently been approved by the Pharmaceutical Affairs Act in Japan.

AREAS COVERED

PubMed was searched from inception until April 2020 with the word evocalcet to summarize the development of this new calcimimetic agent, its pharmacokinetics, and the results of clinical trials, along with an overview of the differences among calcimimetic agents. This review also includes the management of SHPT with a focus on calcimimetics.

EXPERT OPINION

Evocalcet evoked fewer gastrointestinal-related adverse events while suppressing PTH at a lower dose than cinacalcet. These data suggest evocalcet may contribute to better adherence and sufficient dose escalation in patients with SHPT. Whether or not evocalcet improves clinical outcomes remains to be elucidated.

Evocalcet in patients with primary hyperparathyroidism: an open-label, single-arm, multicenter, 52-week, dose-titration phase III study

INTRODUCTION

Primary hyperparathyroidism (PHPT) is caused by parathyroid adenoma, primary parathyroid hyperplasia, or parathyroid carcinoma. For some patients with PHPT controlling serum calcium levels is critical.

MATERIALS AND METHODS

We conducted an open-label, single-arm, 52-week, phase III study in Japanese patients with hypercalcemia due to PHPT to demonstrate efficacy and safety of evocalcet, a new calcimimetic. Patients with intractable PHPT (n = 13), postsurgical recurrence (n = 2), and parathyroid carcinoma (n = 3) were enrolled. Evocalcet administration started at a dose of 2 mg once or twice daily and was titrated to achieve the target serum corrected calcium (cCa) concentration (≤ 10.3 mg/dL) for two consecutive weeks (maximal dose 24 mg/day).

RESULTS

Fourteen patients achieved the target (77.8%; 95% confidence interval [CI] 52.4-93.6). The lower limit of 95% CI exceeded the predetermined reference limit (11%), and thus, efficacy was confirmed. Of 18 patients, 12 (66.7%; 95% CI 41.0-86.7) showed decreased serum cCa of ≥ 1.0 mg/dL from the baseline for two consecutive weeks during the titration phase. Sixteen patients entered the maintenance phase, and 15 patients completed the study. Treatment-emergent adverse events (TEAEs) were recorded in 18/18 patients (100%) and drug-related TEAEs in 8/18 (44.4%). The most commonly observed drug-related TEAE was nausea (2/18 patients). No unexpected drug-related TEAEs were observed. All drug-related TEAEs were mild in severity. No patient discontinued the study because of drug-related TEAEs.

CONCLUSION

Evocalcet demonstrated long-term effectiveness in reducing serum cCa concentrations and safety without any unexpected drug-related TEAEs in PHPT patients.

International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function

The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.

Comparative Effectiveness of Calcimimetic Agents for Secondary Hyperparathyroidism in Adults: A Systematic Review and Network Meta-analysis

RATIONALE & OBJECTIVE

Comparative benefits and harms of calcimimetic agents used for the treatment of secondary hyperparathyroidism have not been well characterized. We sought to compare the effectiveness of 3 calcimimetic agents using published data.

STUDY DESIGN

Systematic review of randomized controlled trials and network meta-analysis.

SETTING & STUDY POPULATION

Adults with chronic kidney disease enrolled in a clinical trial of a calcimetic agent.

SEARCH STRATEGY & SOURCES

MEDLINE, EMBASE, CENTRAL (from February 7, 2013, to November 21, 2019), and a published meta-analysis.

DATA EXTRACTION

Two reviewers independently extracted the study data, assessed risk of bias, and rated evidence certainty using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.

ANALYTICAL APPROACH

Frequentist network meta-analysis was conducted. The primary review outcomes were achievement of a target reduction in serum parathyroid hormone (PTH) levels and hypocalcemia. Additional outcomes were nausea, vomiting, serious adverse events, all-cause mortality, cardiovascular mortality, heart failure, and fracture.

RESULTS

36 trials (11,247 participants) were included. All except 4 trials involved dialysis patients. Median follow-up was 26 weeks (range, 1 week to 21.2 months). Compared with placebo, calcimimetic agents had higher odds of achieving target PTH levels with high or moderate certainty. Etelcalcetide had the highest odds of achieving a PTH target compared with evocalcet (OR, 4.93; 95% CI, 1.33-18.2) and cinacalcet (OR, 2.78; 95% CI, 1.19-6.67). Etelcalcetide appeared to cause more hypocalcemia than cinacalcet and evocalcet. Cinacalcet and to a lesser extent etelcalcetide appeared to cause more nausea than placebo. Differences in risk for mortality, cardiovascular end points, or fractures across calcimimetic agents could not be discerned with sufficient certainty.

LIMITATIONS

Lack of longer-term data; heterogeneous end point definitions.

CONCLUSIONS

Evidence of the benefits of calcimimetic therapy is limited to short-term assessment of a putative surrogate outcome (serum PTH). Although etelcalcetide was associated with the largest reduction in PTH levels, side-effect profiles differed across the 3 calcimimetic agents, making it not possible to identify 1 preferred agent.

Efficacy and Safety of Evocalcet Evaluated by Dialysate Calcium Concentration in Patients with Secondary Hyperparathyroidism Undergoing Hemodialysis

Purpose

Evocalcet is a novel oral calcimimetic drug that has demonstrated similar efficacy to cinacalcet in regulating serum parathyroid hormone (PTH), calcium, and phosphate levels, with fewer upper gastrointestinal tract-related adverse drug reactions (ADRs) in patients with secondary hyperparathyroidism undergoing hemodialysis in Japan. We investigated the efficacy and safety of once-daily oral evocalcet under different dialysate calcium concentrations.

Patients and Methods

A post hoc analysis by dialysate calcium concentration (2.5, 2.75, and 3.0 mEq/L) was performed using data from a previous Phase 3 study that included cinacalcet as an active control. Efficacy endpoints were the proportion of patients who achieved the target intact PTH levels of ≥60 and ≤240 pg/mL between Week 28 and Week 30; time-course changes in serum intact PTH; calcium and phosphorus levels, bone turnover markers, and fibroblast growth factor 23 (FGF23) over the 30-week study period. Safety endpoints were overall ADRs and hypocalcemia- and upper gastrointestinal tract-related ADRs.

Results

A total of 634 patients were included in the analysis. Levels of intact PTH, calcium, phosphate, bone turnover markers, and FGF23 showed improvement in all sub-groups, irrespective of dialysate calcium concentration. The incidence of upper gastrointestinal tract-related ADRs was significantly lower in the evocalcet group than the cinacalcet group with dialysate calcium concentrations of 2.75 and 3.0 mEq/L (p<0.05 for both concentrations).

Conclusion

Evocalcet was effective and safe in regulating the levels of serum intact PTH, calcium, and phosphate in patients with secondary hyperparathyroidism undergoing hemodialysis, irrespective of dialysate calcium concentration.

Evocalcet: A New Oral Calcimimetic for Dialysis Patients With Secondary Hyperparathyroidism

Patients with chronic kidney disease often develop secondary hyperparathyroidism (SHPT), marked by high levels of circulating parathyroid hormone (PTH) and increased risk of morbidity and mortality. Patients with SHPT are treated with a therapeutic combination that commonly includes calcimimetics, which have recently become popular in clinical settings, and other agents such as vitamin D preparations. Calcimimetics are a drug class that reduces PTH levels by targeting the calcium‐sensing receptor. Cinacalcet, a representative calcimimetic, is widely used; however, a high incidence of upper gastrointestinal (GI) tract‐related adverse events (AEs) can result in insufficient dosage and poor long‐term compliance. The newly approved evocalcet has equivalent efficacy to cinacalcet at a lower clinical dose, with improved bioavailability, fewer upper GI tract‐related AEs, and fewer safety concerns. This review gives an overview of calcimimetic agents, with a special focus on evocalcet, and describes the clinical advantages of evocalcet in the treatment of dialysis patients with SHPT.

Effectiveness and safety of cinacalcet for primary hyperparathyroidism: a single center experience

Primary hyperparathyroidism (PHPT) is a common endocrine disease. Although surgical treatment is curative in most cases, there are few alternative therapies for the hypercalcemia caused by PHPT. Cinacalcet is a positive allosteric modulator of the calcium sensing receptor and was conditionally approved in Japan in 2014 to treat PHPT cases. However, there have been few reports on the outcomes. In our present study, we investigated the efficacy and safety of cinacalcet in 61 PHPT patients who were treated with this agent at our hospital between January 2014 and March 2017. The corrected serum Ca and intact PTH levels were significantly reduced by this treatment, whereas the serum phosphorus levels significantly increased. There were no significant differences in the eGFR or urinary Ca to urinary creatinine ratio between baseline and the maintenance phase. In terms of bone mineral density, there were significant increases observed in the 16 cases for whom a baseline value was available, 11 of whom had been treated for osteoporosis. The most common adverse events from cinacalcet treatment were gastrointestinal symptom, such as nausea and appetite loss. Other adverse events included severe dehydration due to hypercalcemia, myalgia, hypocalcemia, and increased urinary calcium excretion. Seven patients were switched to surgical treatment, and the drug was discontinued in 9 other patients, due to adverse effects. Our present study findings demonstrate that cinacalcet is an effective therapeutic option for PHPT from the perspective of hypercalcemia improvement but that adverse gastrointestinal effects of this drug occur at a frequency of about 10%.

Renal insufficiency and bone loss

PURPOSE OF REVIEW

Patients with chronic kidney disease have a high risk of fractures and no established treatments that have been shown to prevent the bone disease. The physiology of renal osteodystrophy is complex and recently more factors have been found that complicate the mineral metabolism. The recognition that vascular calcifications are related to bone disease has made treatment even more challenging.

RECENT FINDINGS

The most exciting new findings relate to the signaling pathways that are seen in kidney disease and how they cause abnormalities in bone physiology. In particular, wnt and activin signaling pathways are seen early in the course of renal disease. The bones react by increasing FGF-23, which targets both renal phosphate secretion and a variety of other systemic effects. Secreted klotho is another newly described hormone with effects on several systems.Clinical studies have focused on treatments for hyperparathyroidism and phosphate, and frustrating limitations of the treatments used for ordinary osteoporosis.

SUMMARY

Treatment of bone disease in patients with chronic kidney disease is challenging, and understanding the physiological pathways could lead to novel therapies.

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.

Efficacy and safety of evocalcet in Japanese peritoneal dialysis patients

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a serious and common complication in patients receiving peritoneal dialysis (PD). Cinacalcet is currently the recommended therapy for SHPT; however, gastrointestinal (GI)-related symptoms can result in low adherence and high discontinuation rates. Evocalcet is a novel calcimimetic agent that has non-inferior efficacy while providing a more tolerable safety profile.

METHODS

This was a multicenter, intra-subject dose-adjustment treatment study evaluating the efficacy and safety of 1-8 mg evocalcet orally administered once daily for 32 weeks for the treatment of SHPT in PD patients. Patients then entered a 20-week extension period (dose range 1-12 mg). The primary endpoint was the proportion of patients who achieved a mean intact parathyroid hormone (iPTH) level of 60-240 pg/mL during the evaluation period (weeks 30-32). Secondary efficacy endpoints included the proportion of patients achieving ≥ 30% decrease in iPTH levels.

RESULTS

A total of 39 Japanese PD patients with SHPT received evocalcet. The target mean iPTH level of 60-240 pg/mL was achieved by 71.8% (28/39) of patients during the evaluation period and 83.3% (20/24) of patients at week 52. The proportion of patients who achieved ≥ 30% decrease in iPTH levels from baseline was 74.4% (29/39) during the evaluation period and 87.5% (21/24) at week 52. Adverse drug reactions occurred in 46.2% (18/39) of patients, with most being of mild-to-moderate severity including GI-related events.

CONCLUSION

This study shows the long-term efficacy and safety of evocalcet when orally administered to PD patients with SHPT once daily.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02549417, https://clinicaltrials.gov/ct2/show/NCT02549417 ; JAPIC: JapicCTI-153016, http://www.clinicaltrials.jp/user/showCteDetailE.jsp?japicId=JapicCTI-153016 .

[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.

Secondary Hyperparathyroidism: Pathogenesis and Latest Treatment

The classic pathogenesis of secondary hyperparathyroidism (SHPT) began with the trade-off hypothesis based on parathyroid hormone hypersecretion brought about by renal failure resulting from a physiological response to correct metabolic disorder of calcium, phosphorus, and vitamin D. In dialysis patients with failed renal function, physiological mineral balance control by parathyroid hormone through the kidney fails and hyperparathyroidism progresses. In this process, many significant genetic findings have been established. Abnormalities of Ca-sensing receptor and vitamin D receptor are associated with the pathogenesis of SHPT, and fibroblast growth factor 23 has also been shown to be involved in the pathogenesis. Vitamin D receptor activators (VDRAs) are widely used for treatment of SHPT. However, VDRAs have calcemic and phosphatemic effects that limit their use to a subset of patients, and calcimimetics have been developed as alternative drugs for SHPT. Hyperphosphatemia also affects progression of SHPT, and control of hyperphosphatemia is, therefore, thought to be fundamental for control of SHPT. Currently, a combination of a VDRA and a calcimimetic is recognized as the optimal strategy for SHPT, and for other outcomes such as reduced cardiovascular disease and improved survival. The latest findings on the pathogenesis and treatment of SHPT are summarized in this review.

Biased agonism and allosteric modulation of metabotropic glutamate receptor 5

Metabotropic glutamate receptors belong to class C G-protein-coupled receptors and consist of eight subtypes that are ubiquitously expressed throughout the central nervous system. In recent years, the metabotropic glutamate receptor subtype 5 (mGlu₅) has emerged as a promising target for a broad range of psychiatric and neurological disorders. Drug discovery programs targetting mGlu₅ are primarily focused on development of allosteric modulators that interact with sites distinct from the endogenous agonist glutamate. Significant efforts have seen mGlu₅ allosteric modulators progress into clinical trials; however, recent failures due to lack of efficacy or adverse effects indicate a need for a better understanding of the functional consequences of mGlu₅ allosteric modulation. Biased agonism is an interrelated phenomenon to allosterism, describing how different ligands acting through the same receptor can differentially influence signaling to distinct transducers and pathways. Emerging evidence demonstrates that allosteric modulators can induce biased pharmacology at the level of intrinsic agonism as well as through differential modulation of orthosteric agonist-signaling pathways. Here, we present key considerations in the discovery and development of mGlu₅ allosteric modulators and the opportunities and pitfalls offered by biased agonism and modulation.

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.