Calcimimetics in CKD-results from recent clinical studies

International Nephrology Masterclass in Chronic Kidney Disease: Rationale, Summary, and Future Perspectives

Chronic kidney disease (CKD) is a progressive condition that affects more than 10% of the population worldwide, accounting for more than 843 million (M) individuals. The prevalence of CKD (844 M patients) is higher than that of diabetes mellitus (422 M patients), cancer (42 M patients), and HIV (37 M patients), but people are often less aware of it. Global expert groups predict reductions in the nephrology workforce in the next decade, with a declining interest in nephrology careers. Over time, KDIGO guidelines have also focused on topics related to the prevention or management of CKD patients in real-life settings. On these premises, a new educational program with international experts in the field of nephrology took place from November 2022 until March 2023 in Milan, Italy. This multinational masterclass provided an educational platform providing unbiased education on diagnosis and treatment by sharing the most recent research data on CKD and comorbidities, therefore creating a snowball effect to increase the implementation of best practices worldwide, using examples from 'real-life' patient outcomes. This paper provides an overview of the International Nephrology Masterclass (INM) concept, summarizing the key lectures and discussions, and giving an outline of future key developments.

Short-term therapy with R568 ameliorated secondary hyperparathyroidism but does not prevent aortic valve calcification in uremic rats

Introduction

Renal failure associated aortic valve calcification (AVC) is the result of hyperphosphatemia and hyperparathyroidism. Calcimimetics is an effective tool for management of secondary hyperparathyroidism. Our goal was to evaluate the effect of the medical intervention with calcimimetic R568 on the AVC process.

Methods and results

The experimental design consisted of administering a uremia-inducing phosphate-enriched diet to rats for six weeks. Rats received a daily R568 injection at different times. Biochemical analysis demonstrated increased urea (34.72 ± 3.57 vs. 5.18 ± 0.15 mmol/L, p<0.05) and creatinine (293.93 ± 79.6 vs. 12.82 ± 1.56 µmol/L, p<0.05). R568 treatment markedly reduced parathyroid hormone (PTH) levels in both treated groups (192.63 ± 26.85, 301.23 ± 101.79 vs. 3570 ± 986.63 pg/mL, p<0.05), with no impact on serum calcium and phosphate. von Kossa staining showed increase in AVC in uremic rats compared to control (1409 ± 159.5 vs. 27.33 ± 25.83, p<0.05). AVC was not affected by R568 in both groups (3343 ± 2462, 1593 ± 792 vs. 1409 ± 159.5, NS). Similarly, the inflammatory marker CD68 was elevated in uremic rats (15592 ± 3792 vs. 181.8 ± 15.29, p<0.01), and was not influenced by R568 treatment (8453 ± 818.5, 9318 ± 2232 vs. 15592 ± 3792, NS). Runt-related transcription factor 2 (Runx2), the regulator of osteoblast differentiation, was upregulated in uremic rats (23186 ± 9226 vs. 3184 ± 2495), that accompanied by elevated levels of Osteopontin (158395 ± 45911 vs. 237.7 ± 81.5, p<0.05) and Osteocalcin (22203 ± 8525 vs. 489.7 ± 200.6, p<0.05). R568 had no impact on osteoblastic markers (Runx2: 21743 ± 3193, 23004 ± 10871 vs. 23186 ± 9226, NS; osteopontin: 57680 ± 19522, 137116 ± 60103 vs. 158395 ± 45911, NS; osteocalcin: 10496 ± 5429, 8522 ± 5031 vs. 22203 ± 8525, NS).

Conclusion

In an adenine-induced uremic rat model, we showed that short-term R568 therapy had no effect on AVC. Treatment with R568 decreased PTH levels but had no effect on high phosphate levels. Regression of AVC necessitates not only a decrease in PTH levels, but also a decline in phosphate levels. To achieve improved outcomes, it is advisable to consider administering a combination of R568 with other medications, such as calcium supplements or phosphate binders. Additional studies are required for further evaluation of the potential treatment of chronic kidney disease (CKD)-associated AVC.

Atherosclerosis Specific Features in Chronic Kidney Disease (CKD)

Atherosclerosis is the major cause of cardiovascular disease, leading to a high mortality rate worldwide. Several risk factors are known to favor atherogenesis, among which are high blood pressure, smoking, diabetes mellitus, and others. Chronic kidney disease is another serious health problem associated with significant health care costs, morbidity, and mortality. Chronic kidney disease shares several risk factors with atherosclerosis and cardiovascular diseases, such as hypertension and diabetes mellitus. Additional risk factors for cardiovascular disease development should be considered in patients with chronic kidney disease. Interestingly, patients suffering from chronic kidney disease are more prone to cardiovascular problems than the general population. Moreover, chronic kidney disease is characterized by an increased atherosclerotic burden from the very early stages. The purpose of this review was to summarize data on atherosclerosis in chronic kidney disease, highlighting the specific features of the disease combination.

Outcomes of Subtotal Parathyroidectomy Versus Total Parathyroidectomy With Autotransplantation for Tertiary Hyperparathyroidism: Multi-institutional Study

OBJECTIVES

Due to the paucity of data and controversy regarding the preferred surgical approach for managing tertiary HPT, we sought to investigate the outcomes of different surgical approaches in managing this challenging disease.

METHODS

We performed a multi-center retrospective study to include patients with tertiary HPT who underwent STPX or total parathyroidectomy with autotransplantation (TPX-A).

RESULTS

One hundred five patients had kidney transplant, and 43 were on dialysis. In the kidney transplant group, 61 patients underwent STPX, and 44 for TPX-A. Patients' demographics were not significantly different (48.61 ± 9.31 vs 47.95 ± 12.73 years, P = 0.759. The postoperative follow-up showed that the TPX-A cohort had a higher rate of hypoparathyroidism (N = 20, 45.45%) versus (N = 14, 22.95%) with the STPX cohort (P = 0.013). The cure among the TPX-A cohorts (84.09%) over the STPX cohort (73.77%) (P = 0.153). The long-term follow-up showed that the rate of developing temporary (N = 16, 41.03%) or permanent (N = 8, 20.51%) hypoparathyroidism was significantly higher among patients who underwent TPX-A over the patients who underwent STPX (N = 7, 17.95%), and (N = 4, 10.26%), respectively (P = 0.012). There was no statistical difference between the persistence (N = 3, 7.69%) or the recurrence (N = 2, 5.13%) of the HPT in the TPX-A cohort and the STPX cohort (N = 2, 5.13%). (N = 4, 10.26%), respectively, P = 0.644.

CONCLUSIONS

To our knowledge, this is the largest multi-center study that compared different approaches for managing tertiary HPT. Showing that STPX is the better modality in patients diagnosed with tertiary HPT and had kidney transplants avoiding the risk of hypoparathyroidism.

Cinacalcet as rescue therapy for refractory hyperparathyroidism in young children with advanced chronic kidney disease

BACKGROUND

Studies in the use of the calcimimetic, cinacalcet, in pediatric chronic kidney disease (CKD) are few and limited to older children with secondary hyperparathyroidism (sHPT), a major morbid complication contributing to poor growth, bone deformities, and cardiovascular disease. Our objectives were to determine a safe and effective dosing regimen of cinacalcet in the treatment of infants and young children with sHPT that was refractory to standard care and to examine their growth during treatment.

METHODS

Ten young pediatric patients with advanced CKD were studied retrospectively during 11 courses of treatment with cinacalcet. All had severe sHPT with intact parathyroid hormone (iPTH) levels ≥ 500 pg/ml and were refractory to standard therapy with phosphate binders and active vitamin D analogs at high doses for > 30 days. The cinacalcet dose was advanced by 50% every 2-4 weeks to achieve a decline in the iPTH to a goal of 150-300 pg/ml. Linear growth was assessed at 6-month intervals by change in z-scores (△SDS) for length before and during cinacalcet therapy.

RESULTS

Median age at initiation of cinacalcet was 18 months (IQR 6, 36) with an average starting dose of 0.7 ± 0.2 mg/kg/day. Median effective dose required to reach iPTH goal of 150-300 pg/ml was 2.8 mg/kg/day (IQR 2.0, 3.1), and time to goal was 112 days (IQR 56, 259) with a median overall decline in iPTH of 82% from baseline by 6 months (p < 0.0001). No subject experienced a clinical adverse event, although 4 had biochemical asymptomatic hypocalcemia. Linear growth improved significantly during cinacalcet therapy (△SDS - 0.62 ± 1.2 versus + 0.91 ± 1.4; p < 0.005). By multiple regression analysis, the primary determinants of growth were concurrent treatment with growth hormone and age < 2 years (R² = 89.6%; p < 0.001). A shorter treatment time required to achieve iPTH goals also was associated with improved growth (r = - 0.75; p < 0.01).

CONCLUSIONS

Cinacalcet may be used effectively and safely in infants and small children with refractory sHPT in advanced CKD using a cautious dosing regimen. Cinacalcet successfully brings iPTH to target level and supports growth when other treatments have been ineffective.

Systematic review of surgical and medical treatment for tertiary hyperparathyroidism

BACKGROUND

A significant proportion of patients with chronic kidney disease and secondary hyperparathyroidism (HPT) remain hyperparathyroid after kidney transplantation, a state known as tertiary HPT. Without treatment, tertiary HPT can lead to diminished kidney allograft and patient survival. Parathyroidectomy was commonly performed to treat tertiary HPT until the introduction of the calcimimetic drug, cinacalcet. It is not known whether surgery or medical treatment is superior for tertiary HPT.

METHODS

A systematic review was performed and medical literature databases were searched for studies on the treatment of tertiary HPT that were published after the approval of cinacalcet.

RESULTS

A total of 1669 articles were identified, of which 47 were included in the review. Following subtotal and total parathyroidectomy, initial cure rates were 98·7 and 100 per cent respectively, but in 7·6 and 4 per cent of patients tertiary HPT recurred. After treatment with cinacalcet, 80·8 per cent of the patients achieved normocalcaemia. Owing to side-effects, 6·4 per cent of patients discontinued cinacalcet treatment. The literature regarding graft function and survival is limited; however, renal graft survival after surgical treatment appears comparable to that obtained with cinacalcet therapy.

CONCLUSION

Side-effects and complications of both treatment modalities were mild and occurred in a minority of patients. Surgical treatment for tertiary HPT has higher cure rates than medical therapy.

Cinacalcet in pediatric and adolescent chronic kidney disease: a single-center experience

Cinacalcet, a calcimimetic drug, has been shown to be efficacious in adult chronic kidney disease (CKD) patients; however, it was not fully studied in pediatric CKD patients. We aimed at assessing the effect of cinacalcet on intact parathyroid hormone (iPTH) secretion in children with CKD-4/5 with iPTH consistently ≥ 300 pg/mL refractory to conventional treatment. This is a prospective cohort analysis of 28 children with uncontrolled hyper-parathyroidism secondary to stage 4 and 5 CKD admitted to a tertiary center during the period from April 2012 to April 2014. Twenty-eight patients with CKD-4/5 were assessed prospectively regarding bone biochemistry, renal ultrasonography, serum iPTH level, and medications. Patients were classified into 3 groups: group 1, 6 patients with CKD-4 on supplemental and supportive therapy; group 2, 6 patients with CKD-5 on hemodialysis and; group 3, 16 patients with CKD-5 on automated peritoneal dialysis. Patients were between the ages of 9 months and 18 years on commencing cinacalcet at doses of 0.5 to 1.5 mg/kg. All patients showed at least a 60% reduction in iPTH (60%-97%). Highly significant reduction in iPTH and serum alkaline phosphatase levels was detected post-cinacalcet. The serum calcium (Ca), phosphate (P), and Ca × P product were unaffected. Treatment was well tolerated with no hypophosphatemia, hypocalcemia, or other adverse effects almost in all patients. Cinacalcet use was proven safe for all pediatric and adolescent patients with CKD-4/5 during the study period, and at the same time most of the patients reached the suggested iPTH target values.

An economic comparison of surgical and medical therapy in patients with secondary hyperparathyroidism--the German perspective

BACKGROUND

Treatment options for secondary hyperparathyroidism were significantly amended with the introduction of cinacalcet and paricalcitol. Limitations of resources in public health systems demand detailed analyses of accruing costs. The aim of this study was to compare the costs of these new treatment modalities to surgery.

METHODS

Patients who underwent initial parathyroidectomy (n = 91) and patients treated with cinacalcet or paricalcitol (n = 100) at an ambulatory dialysis center between 01/2003 and 12/2006 were analyzed. The revenues of both therapies for the funding agencies were calculated by a cost-cost analysis. The real arising costs of the supplier were analyzed and compared to the revenues.

RESULTS

Treatment costs for cinacalcet (60 mg/day/year) were 5828.40€ and 4485.20€ for paricalcitol (15 μg/week/year). Revenues for inpatient surgical treatment according to the German DRG system were 3755.38€/case. Additionally, costs for postoperative ambulatory therapies were 545.05€ for the first year and 384.97€ for the following.

CONCLUSION

Due to linearly increases, expenses of medical treatment with cinacalcet for more than 9 months or paricalcitol for more than 12 months exceeded the costs of surgical therapy. The indication of these new medical therapies should be restricted to patients as an interim solution ahead of surgery or in patients considered unfit for surgery.

Treatment options of secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease stages 3 and 4: an historic review

Secondary hyperparathyroidism (SHPT) is an early complication and a well-known factor negatively affecting cardiovascular mortality already in the late stages of chronic kidney disease (CKD). Negative effects can also be foreseen in early stages of CKD.

AIM

Set against this background, I performed detailed clinical review of the specific literature from 1975 on the various types of trials used to treat SHPT in order to assess their effect on uremic patients affected by CKD stage 3 stage 4.

RESULTS

Out of the 1,820 papers reviewed, I identified 14 prospective controlled randomized trials involving in total 1,587 patients. Dietary approaches and the use of phosphorus chelating agents, either alone or in association, do not seem to be particularly promising for SHPT in uremic patients with CKD stage 3-4. Pending the publication of statistically wellstructured works on CKD stage 3-4, experience with calciummimetic agents in CKD stage 3-4 seems promising, even if there is a need to decrease the side effects most affecting medication compliance and as well safety calcium-mimetic agents seem to be more useful, especially in association with vitamin D derivatives. Further promising results seem to be provided by the latest generations of vitamin D derivatives such as paracalcitol which produces good SHPT control.