Teriparatide and etelcalcetide improve bone, fibrosis, and fat parameters in chronic kidney disease model rats

Objectives

Chronic kidney disease (CKD) complicated by secondary hyperparathyroidism (SHPT) is associated with an increased risk of fragility fractures. Etelcalcetide (EC) is a treatment for SHPT that reduces serum parathyroid hormone (PTH) levels. However, the effects of combined treatment with osteoporosis drugs such as teriparatide (TPTD) remain unclear. This study investigates the combined effects of EC and TPTD on bone in CKD model rats.

Methods

The CKD model was established in 8-week-old male Wistar rats by feeding them a 0.75% adenine diet for 4 weeks. At 20 weeks of age, the rats were divided into 4 groups (N = 9-10 in each group): CKD group (vehicle administration), TPTD group (30 μg/kg, 3 times/week), EC group (0.6 mg/kg, daily), and Comb group (TPTD and EC combined). EC was injected for 12 weeks starting at 20 weeks of age, and TPTD was injected for 8 weeks starting at 24 weeks of age. After treatment, the followings were evaluated: bone mineral density, bone strength, biochemical tests, bone and fat histomorphometry, and micro-computed tomography.

Results

In CKD model rats, the combination of EC and TPTD was more effective in increasing cortical bone thickness and bone strength and inhibiting porosity. In addition, the combined treatment decreased bone marrow adiposity and fibrosis, and it increased bone mass and improved bone microstructure in trabecular bone.

Conclusions

With the observed benefits such as improved bone mass, bone strength, structural properties, and bone marrow adiposity, combination therapy may be a potential way to improve bone fragility in CKD.

Effect of etelcalcetide versus alfacalcidol on left ventricular function and feature-tracking cardiac magnetic resonance imaging in hemodialysis-a post-hoc analysis of a randomized, controlled trial

BACKGROUND

Calcimimetic therapy with etelcalcetide (ETEL) has been shown to attenuate the advancement of left ventricular (LV) hypertrophy in hemodialysis patients measured by cardiac magnetic resonance (CMR). The aim of the study was to evaluate whether this effect is accompanied by alterations in LV function and myocardial composition.

METHODS

This was a post-hoc analysis of a randomized-controlled trial of ETEL versus Alfacalcidol (ALFA) in 62 hemodialysis patients. LV function was assessed using LV ejection fraction (LVEF) and LV global longitudinal strain (GLS) on feature-tracking (FT) CMR. Myocardial tissue characteristics were analyzed using parametric T1 and T2 mapping.

RESULTS

Of the total study cohort (n = 62), 48 subjects completed both CMR scans with sufficient quality for FT analysis. In the one-year follow-up, LV GLS deteriorated in the ALFA group, whereas the ETEL group remained stable (LV GLS change: + 2.6 ± 4.6 versus + 0.3 ± 3.8; p = 0.045 when adjusting for randomization factors and baseline LV GLS). We did not observe a difference in the change of LVEF between the two groups (p = 0.513). The impact of ETEL treatment on LV GLS over time remained significant after additional adjustment for the change in LV mass during the study period. ETEL treatment did not significantly affect other CMR parameters. There were no changes in myocardial composition between treatment groups (T1 time change: + 15 ± 42 versus + 10 ± 50; p = 0.411; T2 time change: - 0.13 ± 2.45 versus - 0.70 ± 2.43; p = 0.652).

CONCLUSIONS

In patients undergoing hemodialysis, treatment with ETEL was protective against deterioration of LV longitudinal function, as evaluated through FT CMR, when compared to the control therapy of ALFA. This effect was not mediated by the change in LV mass. Trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03182699 . Unique identifier: NCT03182699.

Etelcalcetide Inhibits the Progression of Left Atrial Volume Index Compared to Alfacalcidol in Hemodialysis Patients

INTRODUCTION

Increased left atrial (LA) size is a risk factor for cardiovascular events and all-cause mortality. It is closely related to left ventricular hypertrophy and chronic volume overload, both of which are common in hemodialysis. Calcimimetic treatment with etelcalcetide (ETL) previously showed an inhibitory effect on left ventricular mass index (LVMI) progression in this population.

METHODS

This is a post hoc analysis of the EtECAR-HD trial, where 62 patients were randomized to ETL or alfacalcidol (ALFA) for 1 year. LA volume index (LAVI) was measured using cardiac magnetic resonance imaging. The aim of the study was to investigate whether ETL was associated with a change of LAVI.

RESULTS

Median baseline levels of LAVI were 40 mL/m2 (31, 54 IQR) in the ETL group and 36 mL/m2 (26, 46 IQR) in the ALFA group. In the ITT population, the change of LAVI was 5.0 mL/m2 [95% CI: -0.04, 10] lower under ETL, compared to ALFA (p = 0.052, R2adj = 0.259). In the PP population, the difference in LAVI changes widened to 5.8 [95% CI: 0.36, 11], p = 0.037, R2adj = 0.302). Secondary analysis showed that the study delta of LVMI was correlated with the LAVI delta (r = 0.387) and that an inclusion of LVMI delta in the ANCOVA model mediated the effect on LAVI delta to β = 3.3 [95% CI: -0.04, 10] (p = 0.2, R2adj = 0.323). The same could not be observed for parameters assessing the volume status.

CONCLUSIONS

The analysis indicates that ETL could inhibit LAVI progression compared with ALFA. This effect was mediated by the change of LVMI.

Impact of Cinacalcet and Etelcalcetide on Bone Mineral and Cardiovascular Disease in Dialysis Patients

PURPOSES OF REVIEW

With chronic kidney disease (CKD) progression, secondary hyperparathyroidism (sHPT) and mineral and bone metabolism disease (MBD) almost inevitably develop and result in renal osteodystrophy and cardiovascular disease (CVD). Together with active vitamin D, calcimimetics are the main therapy for sHPT in CKD. This review provides an overview of the therapeutic effects of oral cinacalcet and intravenous etelcalcetide on CKD-MBD and vascular disease, with a focus on pediatric dialysis patients.

RECENT FINDINGS

Randomized controlled trials in adults and children demonstrate efficient lowering of parathyroid hormone (PTH) by the calcimimetics together with a reduction in serum calcium and phosphate when combined with low-dose active vitamin D, while therapy with active vitamin D analogs alone increases serum calcium and phosphate. Cinacalcet and etelcalcetide both improve bone formation and correct adynamic bone, i.e., have a direct bone anabolic effect. They decrease serum calciprotein particles, which are involved in endothelial dysfunction, atherogenesis, and vascular calcification. Clinical trials in adults suggest a modest slowing of the progression of cardiovascular calcification with cinacalcet. Calcimimetic agents represent a major pharmacological tool for improved control of CKD-MBD, by efficiently counteracting sHPT and allowing for better control of calcium/phosphate and bone homeostasis. Albeit definite evidence is lacking, the beneficial effects of calcimimetics on CVD are promising. Routine use of cinacalcet has been suggested in children.

Long-term use of etelcalcetide for the treatment of secondary hyperparathyroidism in patients undergoing hemodialysis for end-stage renal failure: a real-life retrospective observational study

BACKGROUND

Patients with end-stage renal failure (ESRD) or dialysis frequently suffer from secondary hyperparathyroidism (sHPTH), a severe complication of mineral metabolism disorders. The calcimimetic etelcalcetide has been approved and shown efficacy in randomized controlled trials, however, data are limited from real-life studies. This study aimed to evaluate the long-term use etelcalcetide for the treatment of sHPTH (PTH > 600 pg/mL) in patients undergoing extracorporeal hemodialysis for ESRD for at least 2 years.

METHODS

In 45 patients, we administered etelcalcetide for the treatment of sHPTH (PTH > 600 pg/mL); One group of patients (control group, Group A; N = 26) were previously treated with intravenous vitamin D analogues only (paricalcitol 5 µg/ml, three times/week) and then treated with etelcalcetide and a second group of patients already on cinacalcet therapy for at least six months in combination with iv paricalcitol were switched to etelcalcetide (Group B, N = 19).

RESULTS

PTH levels decreased over time in both groups of patients, with higher values for patients previously treated with cinacalcet (Group B) compared to Group A for the entire study duration even if the final value of the two groups was comparable. After 12 months, the percentage of subjects who had PTH concentrations within the targets recommended by KDIGO guidelines was 87% in Group A and 58% in Group B. In seven patients, despite a parathyroid gland volume > 1000 mm³, an adequate response in the reduction of PTH was obtained.

CONCLUSION

Findings from this study demonstrate that the efficacy of etelcalcetide is maintained over the long term.

Etelcalcetide controls secondary hyperparathyroidism and raises sclerostin levels in hemodialysis patients previously uncontrolled with cinacalcet

INTRODUCTION

There is scarce clinical experience with etelcalcetide in patients with secondary hyperparathyroidism uncontrolled with cinacalcet. The effect of etelcalcetide on serum sclerostin levels remains to be clarified.

MATERIALS AND METHODS

Prospective cohort study in prevalent hemodialysis patients with uncontrolled sHPT under cinacalcet for at least 3 months, mean parathyroid hormone (PTH)>800pg/mL and calcium (Ca)>8.3mg/dL. Etelcalcetide 5mg IV/HD was initiated after cinacalcet washout. Levels of PTH, Ca, and phosphorus (Pi) followed monthly for 6 months. Plasma sclerostin levels measured before etelcalcetide treatment and after 6 months.

RESULTS

Thirty-four patients were enrolled, 19 (55.9%) male gender. Mean age 60.7 (± 12.3) years; median time on HD 82.5 (7-296) months and median cinacalcet dose was 180mg/week (Interquartile Range: 180-270). Serum Ca, Pi and PTH levels showed a significant reduction after etelcalcetide treatment from 8.8mg/dL, 5.4mg/dL and 1005pg/mL to 8.1mg/dL (p=0.08), 4.9mg/dL (p=0.01) and 702pg/mL (p<0.001), respectively. Median etelcalcetide dose remained at 5mg/HD. Plasma sclerostin concentration increased from 35.66pmol/L (IQR11.94-54.58) to 71.05pmol/L (IQR54.43-84.91) (p<0.0001).

CONCLUSION

Etelcalcetide improved sHPT control in this group of patients, previously under cinacalcet treatment, and significantly increased plasma sclerostin concentration. The impact of etelcalcetide treatment on sclerostin levels is a novel finding.

Cortical porosity development and progression is mitigated after etelcalcetide treatment in an animal model of chronic kidney disease

PURPOSE

Chronic kidney disease (CKD) leads to increased bone fragility and risk of fracture. Cortical deteriorations, including cortical porosity, are key factors in fracture susceptibility in CKD. Since secondary hyperparathyroidism is common in CKD individuals and contributes to cortical deterioration, we hypothesized that reducing parathyroid hormone (PTH) may modulate CKD-induced cortical porosity. The goal of this pilot study was to assess the effects of lowering PTH, via the preclinical analogue of the FDA-approved calcimimetic etelcalcetide (KP-2326), on the development and progression of cortical pores in the setting of CKD.

METHODS

Male Cy/+ Sprague Dawley rats with clinical biochemistries consistent with CKD (N = 8) were assigned to the study. At 30-32 weeks of age, cortical bone was assessed via In vivo μCT and blood collected for biochemistries to create baseline measures. Calcimimetic treatment with KP-2326 (KP) was then administered 3× weekly for 2-4 weeks. Cortical bone and biochemical parameters were repeated at study endpoint (33-37 wks of age). A group of age- and cohort-matched CKD rats (N = 4) were utilized as untreated controls.

RESULTS

Untreated CKD rats had significantly increased cortical porosity over time, while porosity in KP-treated CKD rats was not significantly changed over time. Individual pore analysis revealed that pore area was significantly higher for expanding pores in untreated CKD rats compared to KP-treated CKD rats. Mechanical properties of KP-treated animal femora were similar to historical values of age-matched CKD animals and lower than those of age-matched non-diseased animals.

CONCLUSION

Our pilot preclinical study demonstrates that etelcalcetide treatment can mitigate the progression of cortical bone changes in an animal model of CKD through suppression of pre-existing cortical pore expansion and limiting the size of new pore development. While stabilization of porosity is beneficial it remains likely that infilling of porosity will be needed to positively affect mechanical properties of bones in the setting of CKD.

Does Etelcalcetide reverse myelofibrotic bone changes due to hyperparathyroidism? A case report

Secondary hyperparathyroidism (SHPT) in dialysis is common. A young man on chronic hemodialysis with SHPT developed pancytopenia with resistant anemia requiring transfusions. A bone marrow biopsy showed grade 3 fibrosis, depleted cellularity, osteosclerosis, and decreased myelopoiesis. He initiated Etelcalcetide 7⋅5 mg 3 times weekly with improvement in SHPT concomitant with near normalization of blood counts. Marrow biopsy at 12 months showed clearance of marrow reticulin, improvement of osteosclerosis and normalization of bone trabeculae, cellularity and myelopoiesis. This is a unique case in which Etelcalcetide treatment is comparable to parathyroidectomy on SHPT and is associated with significant improvement in severe myelofibrosis.

Etelcalcetide decreases the PTH-calcium setpoint without changing maximum and minimum PTH secretion in mice with primary hyperparathyroidism

INTRODUCTION

Etelcalcetide binds to the extracellular domain of the calcium-sensing receptor (CaSR), while cinacalcet binds to the 7-transmembrane domain of the CaSR; however, it is unknown, whether etelcalcetide has similar effects to cinacalcet on parathyroid hormone (PTH) secretion.

MATERIALS AND METHODS

The PTH-calcium setpoint and maximum and minimum PTH secretion were determined using an 'in vivo setpoint analyses.' The PTH-calcium setpoint was obtained in a mouse model of primary hyperparathyroidism (PC) and wild-type (WT) mice, with PC mice divided into two groups. The setpoint was obtained after 7 days of etelcalcetide (3.0 mg/kg BW/day) or vehicle administration via anosmotic pump. After 7 days of crossover administration, the setpoint was obtained again. Parathyroid glands were obtained after crossover administration, and CaSR expression was analyzed by immunohistochemistry.

RESULTS

Etelcalcetide administration significantly decreased the setpoint from 9.03 ± 0.56 mg/dL to 6.80 ± 0.28 mg/dL, which was restored to 8.81 ± 0.38 mg/dL after vehicle administration. In the second group of mice, vehicle administration did not alter the setpoint (8.84 ± 0.69 mg/dL to 8.98 ± 0.63 mg/dL), but subsequent etelcalcetide administration significantly decreased it to 7.10 ± 0.72 mg/dL. There was no significant change in maximum and minimum PTH secretion. Expression levels of parathyroid CaSR were lower in PC mice than in WT mice; however, no significant differences were observed between the two mouse groups.

CONCLUSION

Etelcalcetide decreased the PTH-calcium setpoint without changing maximum and minimum PTH secretion in PC mice, suggesting that like cinacalcet, etelcalcetide has calcimimetic potency.

Phase 1, single-dose study to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of etelcalcetide in pediatric patients with secondary hyperparathyroidism receiving hemodialysis

BACKGROUND

Data on the safety, efficacy of etelcalcetide in children with secondary hyperparathyroidism (sHPT) are limited.

METHODS

This phase 1 study (NCT02833857) evaluated the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) of single-dose etelcalcetide (0.035 mg/kg intravenously) in pediatric hemodialysis patients (two cohorts; 1: 12-< 18 years; 2: 2-< 12 years). Treatment-emergent adverse events (AEs), PK/PD were assessed post-dose on D1 at 10 min and 4 h, on multiple days until D10, and at end of study (D30).

RESULTS

Etelcalcetide administered to 11 patients (mean [SD] age 10.3 [4.3] years; cohort 1, n = 6; cohort 2, n = 5) was well tolerated. AEs were consistent with established safety profiles in adults. Two patients (1 per cohort) reported treatment-related AEs (cohort 1: hypocalcemia; cohort 2: headache, paresthesia, vomiting). No serious AEs or deaths were reported. Mean serum corrected calcium (cCa) for all patients was maintained > 2.25 mmol/L. After etelcalcetide dosing, PK exposures declined, with mean C_max, AUC_last, and AUC_inf exposures higher in cohort 1. Median percent change in serum intact parathyroid hormone (iPTH) from baseline (cohort 1: 51.2 pmol/L; cohort 2: 84.0 pmol/L) reached the nadir on D1 at 4 h (cohort 1: - 33.4%; cohort 2: - 64.2%). Mean total calcium and cCa reached nadirs on D3 at 2.39 mmol/L, and ionized Ca on D1 at 4 h.

CONCLUSIONS

Single-dose etelcalcetide (0.035 mg/kg) was well tolerated with expected PK and safety profiles. Overall pattern of changes in serum iPTH and serum calcium was similar between cohorts and consistent with expected responses to etelcalcetide.

Safety and efficacy of etelcalcetide, an intravenous calcimimetic, for up to 52 weeks in hemodialysis patients with secondary hyperparathyroidism: results of a post-marketing surveillance in Japan

Background

Etelcalcetide is a second-generation calcimimetic for the management of secondary hyperparathyroidism (SHPT) in patients on dialysis. We performed a post-marketing surveillance (PMS) to obtain information on the safety and efficacy of etelcalcetide in clinical practice in Japan.

Methods

This PMS enrolled SHPT patients who started initial treatment with etelcalcetide between April 1, 2017 and February 28, 2018 in Japan. Safety [adverse drug reactions (ADRs)] and efficacy [serum intact parathyroid hormone (iPTH), corrected calcium (cCa), phosphorous (P), and alkaline phosphatase (ALP)] were recorded for up to 52 weeks or until treatment discontinuation. Treatment decisions were at the physician’s discretion.

Results

Of 1226 patients enrolled across 282 centers, safety and efficacy data were available for 1195 and 1192, respectively, while 933 continued treatment to Week 52. The starting dose was 5 mg in 82.0% of patients. There were 218 ADRs in 169 patients (14.1%). Metabolism and nutrition disorders (8.8%), adverse laboratory test results (1.8%), and gastrointestinal disorders (1.6%) were the most frequent classes of ADRs. Hypocalcemia-related ADRs occurred in 104 patients (8.7%). The percentage of patients with iPTH levels within the target range (60–240 pg/mL) steadily increased from 19.5% at Week 0 to 64.1% at Week 52 or last dose. cCa, P, and ALP levels remained well controlled.

Conclusion

This was the first real-world, large-scale, long-term observational PMS of etelcalcetide in Japan. We did not observe any new safety concerns. Etelcalcetide was associated with clinically relevant improvements in serum iPTH and maintenance of serum cCa, P, and ALP levels.

Electronic supplementary material

The online version of this article (10.1007/s10157-020-01936-2) contains supplementary material, which is available to authorized users.

Position paper of working group on CKD-MBD of the Italian Society of Nephrology

Bone mineral abnormalities (defined as Chronic Kidney Disease Mineral Bone Disorder; CKD-MBD) are prevalent and associated with a substantial risk burden and poor prognosis in CKD population. Several lines of evidence support the notion that a large proportion of patients receiving maintenance dialysis experience a suboptimal biochemical control of CKD-MBD. Although no study has ever demonstrated conclusively that CKD-MBD control is associated with improved survival, an expanding therapeutic armamentarium is available to correct bone mineral abnormalities. In this position paper of Lombardy Nephrologists, a summary of the state of art of CKD-MBD as well as a summary of the unmet clinical needs will be provided. Furthermore, this position paper will focus on the potential and drawbacks of a new injectable calcimimetic, etelcalcetide, a drug available in Italy since few months ago.

A hemodialysis patient with bone disease after pregnancy: a case report

Background

Pregnancy is rare in women on hemodialysis. Recommendations for the treatment of secondary hyperparathyroidism (sHPT) and preservation of bone health in pregnant dialysis patients are lacking.

Case presentation

We present the case of a young woman with end-stage kidney disease (ESKD) due to lupus nephritis, who developed multiple brown tumors while on hemodialysis during her second pregnancy. During her first pregnancy sHPT was well controlled and no skeletal complications occurred. Before the second pregnancy she developed severe sHPT. During pregnancy, dialysis time was increased to 24 h per week, the patient was given oral calcitriol, and the dialysate calcium concentration was set at 1.5 mmol/l. In week 20 the patient complained about bone pain in her left hip. Magnetic resonance imaging revealed a cystic lesion compatible with a brown tumor. The baby was delivered in the 36th week by cesarean section. Further assessment identified multiple brown tumors of her skeleton, including the acetabulum, tibia, ribs, skull, thoracic spine and thumb. She required multiple orthopedic surgeries. Three months after pregnancy, etelcalcetide was started, which brought about a gradual improvement in her sHPT.

Conclusions

This case demonstrates that the combination of pregnancy and severe sHPT in dialysis patients can have deleterious consequences for bone health.

Effect of etelcalcetide on cardiac hypertrophy in hemodialysis patients: a randomized controlled trial (ETECAR-HD)

Background

Fibroblast growth factor 23 (FGF23) is associated with left ventricular hypertrophy (LVH) in patients with chronic kidney disease, and calcimimetic therapy reduces plasma concentrations of FGF23. It remains unknown whether treatment with the calcimimetic etelcalcetide (ETL) reduces LVH in patients on hemodialysis.

Methods/design

This single-blinded randomized trial of 12 months duration will test the effects of ETL compared with alfacalcidol on LVH and cardiac fibrosis in maintenance hemodialysis patients with secondary hyperparathyroidism. Both treatment regimens will be titrated to equally suppress secondary hyperparathyroidism while alfacalcidol treatment causes an increase and ETL a decrease in FGF23, respectively.

Patients treated thrice weekly with hemodialysis for ≥ 3 months and ≤ 3 years with parathyroid hormone levels ≥ 300 pg/ml and LVH will be enrolled in the study.

The primary study endpoint is change from baseline to 12 months in left ventricular mass index (LVMI; g/m²) measured by cardiac magnetic resonance imaging. Sample size calculations showed that 62 randomized patients will be necessary to detect a difference in LVMI of at least 20 g/m² between the two groups at 12 months. Due to the strong association of volume overload and LVH, randomization will be stratified by residual kidney function, and regular body composition monitoring will be performed to control the volume status of patients.

Study medication will be administered intravenously by the dialysis nurses after every hemodialysis session, thus omitting adherence issues.

Secondary study endpoints are cardiac parameters measured by echocardiography, biomarker concentrations of bone metabolism (FGF23, vitamin D, parathyroid hormone, calcium, phosphate, s-Klotho), cardiac markers (pro-brain natriuretic peptide, pre- and postdialysis troponin T) and metabolites of the renin–angiotensin–aldosterone cascade (angiotensin I (Ang I), Ang II, Ang-(1–7), Ang-(1–5), Ang-(1–9), and aldosterone).

Discussion

The causal inference and pathophysiology of LVH regression by FGF23 reduction using calcimimetic treatment has not yet been shown. This intervention study has the potential to discover a new strategy for the treatment of cardiac hypertrophy and fibrosis in patients on maintenance hemodialysis. It might be speculated that successful treatment of cardiac morphology will also reduce the risk of cardiac death in this population.

Trial registration

European Clinical Trials Database, EudraCT number 2017-000222-35; ClinicalTrials.gov, NCT03182699. Registered on

Calcimimetics and Bundled Reimbursement

Since 2011, the Centers for Medicare & Medicaid Services has provided reimbursement for renal dialysis services furnished to Medicare beneficiaries through a bundled payment system known as the Prospective Payment System. Medications that have no injectable equivalent, known as "oral-only medications," are currently excluded from the bundle and are paid separately through Medicare Part D. Thus, before the development of etelcalcetide, the first injectable calcimimetic, calcimimetics were reimbursed outside the bundle. Etelcalcetide's introduction and approval for use in Medicare triggered a transition payment for a minimum of 2 years that will eventually result in the incorporation of calcimimetics into the dialysis bundle. Consequently, providers may face incentives to reduce calcimimetic use when the transition period has expired. The complexity of bone-mineral management in conjunction with the paucity of evidence-based recommendations in this area makes it difficult to predict the impact of this transition. Because these medications are expensive, a poor transition could have financial ramifications for dialysis organizations and potentially patient health. To ensure that patients are not adversely affected, it is critical that Medicare incorporate these medications into the bundle carefully, with close monitoring of outcomes.

Discovery and Development of Calcimimetic and Calcilytic Compounds

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

Etelcalcetide, A Novel Calcimimetic, Prevents Vascular Calcification in A Rat Model of Renal Insufficiency with Secondary Hyperparathyroidism

Etelcalcetide, a novel peptide agonist of the calcium-sensing receptor, prevents vascular calcification in a rat model of renal insufficiency with secondary hyperparathyroidism. Vascular calcification occurs frequently in patients with chronic kidney disease (CKD) and is a consequence of impaired mineral homeostasis and secondary hyperparathyroidism (SHPT). Etelcalcetide substantially lowers parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) levels in SHPT patients on hemodialysis. This study compared the effects of etelcalcetide and paricalcitol on vascular calcification in rats with adenine-induced CKD and SHPT. Uremia and SHPT were induced in male Wistar rats fed a diet supplemented with 0.75% adenine for 4 weeks. Rats were injected with vehicle, etelcalcetide, or paricalcitol for 4 weeks from the beginning of adenine diet. Rats fed an adenine-free diet were included as nonuremic controls. Similar reductions in plasma PTH and parathyroid chief cell proliferation were observed in both etelcalcetide- and paricalcitol-treated rats. Serum calcium and phosphorus were significantly lower in etelcalcetide-treated uremic rats and was unchanged in paricalcitol-treated rats. Both serum FGF23 and aortic calcium content were significantly lower in etelcalcetide-treated uremic rats compared with either vehicle- or paricalcitol-treated uremic rats. The degree of aortic calcium content for etelcalcetide-treated rats was similar to that in nonuremic controls and corroborated findings of lack of histologic aortic mineralization in those groups. In conclusion, etelcalcetide and paricalcitol similarly attenuated progression of SHPT in an adenine rat model of CKD. However, etelcalcetide differentially prevented vascular calcification, at least in part, due to reductions in serum FGF23, calcium, and phosphorus levels.

Exploring the potential value of improved care for secondary hyperparathyroidism with a novel calcimimetic therapy

AIMS

This study explored the use of a value-based pricing approach for the new calcimimetic etelcalcetide indicated for the treatment of secondary hyperparathyroidism (SHPT) in patients receiving hemodialysis. It used the US payer perspective and applied the cost-effectiveness framework. Because etelcalcetide is an intravenous therapy that can be titrated for individual patients, and because its utilization is yet to be assessed in real world settings, a range of plausible doses were estimated for etelcalcetide to define a range of prices. These were either in relation to the existing oral calcimimetic cinacalcet or compared to no calcimimetic treatment.

MATERIALS AND METHODS

The value-based price of etelcalcetide was determined via a Markov model. This model combined data from the etelcalcetide trials and previously published cost-effectiveness models in SHPT, and allowed extrapolation of treatment effects on mortality, cardiovascular events, fracture, and parathyroidectomy. Several dosing scenarios were explored covering the dose ranges of 30.0-64.18 mg per day for cinacalcet and 1.07-3.11 mg per day for etelcalcetide. These included the mean dose from the etelcalcetide trials, the preliminary defined daily dose, and the expected most common dose in real world. An acceptable price range for etelcalcetide was assessed by comparing the incremental cost-effectiveness ratios obtained with the willingness-to-pay threshold range of $100,000-$300,000/quality-adjusted life-years.

RESULTS

Cost-effectiveness analysis supported value-based prices for etelcalcetide ranging from $21.15-$49.97/mg vs cinacalcet, and $13.79-$119.45/mg vs no calcimimetics.

LIMITATIONS

There is uncertainty around what the real-world dosing will be for etelcalcetide. Another important nuance is that no studies have examined etelcalcetide effects on hard outcomes and, therefore, this modeling exercise relied on an extrapolation approach.

CONCLUSIONS

This cost-effectiveness analysis, including scenarios to address uncertainties, allowed estimation of a value-based price range to aid reimbursement decisions in the US.

Long-term effects of etelcalcetide as intravenous calcimimetic therapy in hemodialysis patients with secondary hyperparathyroidism

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a serious major complication in hemodialysis patients with chronic kidney disease. Long-term maintenance of serum phosphate, calcium, and parathyroid hormone (PTH) levels in appropriate ranges in these patients is a major challenge. We investigated the efficacy and safety of long-term treatment with etelcalcetide, a novel intravenous calcimimetic, in Japanese SHPT patients on long-term hemodialysis.

METHODS

This study was a multicenter open-label study. A total of 191 hemodialysis patients with serum intact PTH (iPTH) > 240 pg/mL were enrolled. Etelcalcetide was administered thrice weekly for 52 weeks, with an initial dose of 5 mg and flexibility to adjust the dose between 2.5 and 15 mg and to adjust the dosing of concomitant medications for SHPT. The efficacy endpoint was the proportion of patients with serum iPTH decreased to the target range (60-240 pg/mL).

RESULTS

Serum iPTH levels decreased immediately after etelcalcetide was started. At the end of the study, 87.5% (95% confidence interval 81.4-92.2; 140/160 patients) of patients achieved target serum iPTH levels, with control of serum calcium and phosphate levels. Adverse events, mostly mild to moderate, were reported by 96.8% of patients and led to study discontinuation in 7.4% of patients. Nausea, vomiting, and symptomatic hypocalcemia were found in 4.7, 9.5, and 1.1%, with 0.5, 1.1, and 1.1% considered treatment-related.

CONCLUSIONS

Etelcalcetide effectively maintained serum iPTH, calcium, and phosphate levels in appropriate ranges with concomitant medications for SHPT for 52 weeks in Japanese hemodialysis patients, and was safe and well tolerated.

REGISTRATION NUMBER

JapicCTI-142665.

Drug disposition model of radiolabeled etelcalcetide in patients with chronic kidney disease and secondary hyperparathyroidism on hemodialysis

Etelcalcetide (AMG 416) is an allosteric activator of the calcium-sensing receptor for treatment of secondary hyperparathyroidism in patients with chronic kidney disease (CKD) on hemodialysis. To characterize the time course of etelcalcetide in different matrices (plasma, dialysate, urine, and feces), a drug disposition model was developed. Nonlinear mixed-effect modeling was used to describe data from six adults with CKD on hemodialysis who received a single intravenous dose of [¹⁴C]etelcalcetide (10 mg; 710 nCi) after hemodialysis (study NCT02054572). A three-compartment model with the following attributes adequately described the observed concentration-time profiles of etelcalcetide in the different matrices: biotransformation in the central compartment; elimination in dialysate, urine, and feces; and a nonspecific elimination process. The terminal half-life of total C-14 in plasma was approximately 56 days. The ratio of conjugation-deconjugation rate constants between etelcalcetide and biotransformed products was 11.3. Simulations showed that three hemodialysis sessions per week for 52 weeks would contribute to 60.1% of the total clearance of etelcalcetide following single-dose intravenous etelcalcetide administration. Minimal amounts were eliminated in urine (2.5%) and feces (5.7%), whereas nonspecific elimination accounted for 31.2% of total elimination. In addition to removal of etelcalcetide, ~10% of small-molecular weight biotransformed products was estimated to have been removed through hemodialysis and in urine. This model provided a quantitative approach to describe biotransformation, distribution, and elimination of etelcalcetide, a unique synthetic D-amino acid peptide, in the relevant patient population.