Evolution of Secondary Hyperparathyroidism After Kidney Transplantation in Patients Receiving Cinacalcet on Dialysis

Etelcalcetide use During Maintenance Hemodialysis and Incidence of Parathyroidectomy After Kidney Transplantation

Introduction

Etelcalcetide is an i.v. calcimimetic agent, effectively reducing parathyroid hormone levels in patients on maintenance hemodialysis (HD). The clinical impact of discontinuing etelcalcetide at the time of kidney transplantation is unknown.

Methods

We retrospectively reviewed all patients on HD meeting predefined criteria who received a kidney transplant at our institution between January 1, 2015, and December 12, 2022. The incidence of parathyroidectomy and the evolution of calcium, phosphate, and intact parathyroid hormone (iPTH) levels after transplantation was analyzed according to the type of calcimimetic treatment before transplantation (cinacalcet vs. etelcalcetide vs. none).

Results

Overall, 372 patients (aged 53 years; interquartile range [IQR]: 42-62 years) were included. At the time of transplantation, 35, 75, and 262 patients were under etelcalcetide, cinacalcet, or no calcimimetic, respectively. After 1064 (IQR: 367-1658) days, the incidences of parathyroidectomy in the etelcalcetide, cinacalcet, no calcimimetic groups were 29%, 12%, and 1%, respectively (P < 0.001). Etelcalcetide was associated with an increased incidence of parathyroidectomy after adjustment for age, sex, and HD vintage (hazard ratio [HR]: 97.0, 95% confidence interval [CI]: 19.1-493.9, P < 0.001). The incidence of parathyroidectomy was related to etelcalcetide dosage (6/11 [54.6%] in patients with ≥ 10 mg vs. 4/24 [16.7%] in patients with < 10 mg, P = 0.02). Moreover, peak calcium levels were higher (P < 0.001) and parathyroidectomy was performed earlier (median 80 vs. 480 days, P < 0.001) in the etelcalcetide compared with the cinacalcet group. Long-term graft function, graft loss, and mortality were similar.

Conclusion

Etelcalcetide use during maintenance HD is associated with an increased incidence of early parathyroidectomy after transplantation compared to cinacalcet or no calcimimetic.

Bone Mineral Disease After Kidney Transplantation

Chronic kidney disease-mineral bone disorder (CKD-MBD) after kidney transplantation is a mix of pre-existing disorders and new alterations. The final consequences are reflected fundamentally as abnormal mineral metabolism (hypercalcemia, hypophosphatemia) and bone alterations [high or low bone turnover disease (as fibrous osteitis or adynamic bone disease), an eventual compromise of bone mineralization, decrease bone mineral density and bone fractures]. The major cause of post-transplantation hypercalcemia is the persistence of severe secondary hyperparathyroidism, and treatment options include calcimimetics or parathyroidectomy. On turn, hypophosphatemia is caused by both the persistence of high blood levels of PTH and/or high blood levels of FGF23, with its correction being very difficult to achieve. The most frequent bone morphology alteration is low bone turnover disease, while high-turnover osteopathy decreases in frequency after transplantation. Although the pathogenic mechanisms of these abnormalities have not been fully clarified, the available evidence suggests that there are a number of factors that play a very important role, such as immunosuppressive treatment, persistently high levels of PTH, vitamin D deficiency and hypophosphatemia. Fracture risk is four-fold higher in transplanted patients compared to general population. The most relevant risk factors for fracture in the kidney transplant population are diabetes mellitus, female sex, advanced age (especially > 65 years), dialysis vintage, high PTH levels and low phosphate levels, osteoporosis, pre-transplant stress fracture and high doses or prolonged steroids therapy. Treatment alternatives for CKD-MBD after transplantation include minimization of corticosteroids, use of calcium and vitamin D supplements, antiresorptives (bisphosphonates or Denosumab) and osteoformers (synthetic parathyroid hormone). As both mineral metabolism and bone disorders lead to increased morbidity and mortality, the presence of these changes after transplantation has to be prevented (if possible), minimized, diagnosed, and treated as soon as possible.

Impact of cinacalcet pre-transplantation on mineral metabolism in renal transplant recipients

AIM

Cinacalcet is effective in reducing parathyroid hormone (PTH) in patients on dialysis. Reports of biochemical profiles and other clinical outcomes in patients discontinuing cinacalcet at time of renal transplantation are limited.

METHODS

A retrospective study assessing markers of mineral metabolism, graft and patient outcomes in renal transplant recipients to determine differences in patients discontinuing cinacalcet (C+) compared with patients not treated with cinacalcet (C-) at time of transplantation. To allow for differences between groups in pre-transplant biochemical parameters, we also analysed a matched cohort of C- with C+ recipients (2:1), matched for age, calcium and PTH levels at transplantation.

RESULTS

Five hundred thirty-two recipients (460 C-, 72 C+), transplanted January 2006-December 2012, were analysed, mean age 48.0 ± 12.7 years and 64.3% were men. At a median 42.9 months follow up, there were 10 deaths (1.9%), 56 allograft loss (10.6%) and 5 parathyroidectomies post-transplant (0.8%). Median PTH immediately pre-transplant was higher in C+ versus C- (50.7(25.4-75.2) versus 28.3(13.9-49.7) pmol/L, P < 0.001). Twelve-month post-transplant PTH was reduced but higher in C+ (11.7(6.9-21.2) vs 7.2(4.6-11.2) pmol/L, P < 0.001). Mean calcium was higher for C+ versus C- at 12 months (2.50 ± 0.19 vs 2.43 ± 0.17 mmol/L, P < 0.001), with differences to 4 years post-transplant. No difference was seen in renal function, graft loss, post-transplant parathyroidectomy rate and mortality. In the matched cohort (144 C- vs 72 C+), similar findings were also seen.

CONCLUSION

Differences in mineral metabolism post-transplant are seen with cinacalcet pre-transplant compared with no cinacalcet. Transplant recipients discontinuing cinacalcet had higher post-transplant PTH and calcium although the clinical significance is unclear.

A Prospective Cohort Study of Mineral Metabolism After Kidney Transplantation

Kidney transplantation corrects or improves many complications of chronic kidney disease, but its impact on disordered mineral metabolism is incompletely understood.

The prevalence of posttransplant hyperparathyroidism was 86% at 12 months (PTH >65 pg/ml) but only 40% (PTH >130 mg/dL) in the absence of cinacalcet, vitamin D sterols, or parathyroidectomy. Intact fibroblast growth factor 23 decreased rapidly to G40 pg/ml by 3 months posttransplant. Supplemental digital content is available in the text.

Changes in bone mineral metabolism parameters, including FGF23, after discontinuing cinacalcet at kidney transplantation

Little is known about the effects of the administration of cinacalcet in dialytic patients who are scheduled for kidney transplantation, and in particular about the changes in FGF23 and other mineral metabolism parameters after surgery compared with recipients not on cinacalcet at kidney transplantation. We performed a prospective observational cohort study with recruitment of consecutive kidney transplant recipients at our institution. Patients were classified according to whether they were under treatment with cinacalcet before transplantation. Bone mineral metabolism parameters, including C-terminal FGF23, were measured at baseline, on day 15, and at 1, 3, and 6 months after transplantation. In previously cinacalcet-treated patients, cinacalcet therapy was discontinued on the day of surgery and was not restarted after transplantation. A total of 48 kidney transplant recipients, 20 on cinacalcet at surgery and 28 cinacalcet non-treated patients, completed the follow-up. Serum phosphate declined significantly in the first 15 days after transplantation with no differences between the two groups, whereas cinacalcet-treated patients showed higher FGF23 levels, although not significant. After transplantation, PTH and serum calcium were significantly higher in cinacalcet-treated patients. We conclude that patients receiving cinacalcet on dialysis presented similar serum phosphate levels but higher PTH and serum calcium levels during the initial six months after kidney transplantation than cinacalcet non-treated patients. The group previously treated with cinacalcet before transplantation showed higher FGF23 levels without significant differences, so further studies should investigate its relevance in the management of these patients.

Effect of cinacalcet cessation on hyperparathyroidism in kidney transcaplant patients after long-term dialysis therapy

BACKGROUND

Cinacalcet is a promising therapy widely used in dialysis patients with hyperparathyroidism resistant to conventional therapy. However, reports regarding the influence of cinacalcet cessation after long-term use on kidney transplantation patients are few.

METHODS

This retrospective observational study included 40 dialysis patients who underwent kidney transplantation. Creatinine, corrected calcium, phosphorus, alkaline phosphatase, and intact parathyroid hormone levels were assessed before and after kidney transplantation according to pretransplant treatment of chronic kidney disease-mineral and bone disorder.

RESULTS

Ultrasonography revealed enlargement of the parathyroid in all patients treated with cinacalcet. Although the data at the time of kidney transplantation were comparable, the serum levels of calcium, alkaline phosphatase, and intact parathyroid hormone after kidney transplantation were higher in patients treated with cinacalcet than in those treated without. However, serum phosphate levels in the cinacalcet group were slightly higher at the time of kidney transplantation and significantly lower 3 months later.

CONCLUSIONS

Mineral abnormalities persisted in kidney transplant patients with enlarged parathyroid glands after discontinuation of cinacalcet treatment. Parathyroidectomy should be considered in kidney transplant candidates with the risk of developing refractory hyperparathyroidism after transplantation.

A randomized study evaluating cinacalcet to treat hypercalcemia in renal transplant recipients with persistent hyperparathyroidism

Persistent hyperparathyroidism (HPT) after kidney transplantation (KTx) is associated with hypercalcemia, hypophosphatemia and abnormally high levels of parathyroid hormone (PTH). In this randomized trial, cinacalcet was compared to placebo for the treatment of hypercalcemia in adult patients with persistent HPT after KTx. Subjects were randomized 1:1 to cinacalcet or placebo with randomization stratified by baseline corrected total serum calcium levels (≤11.2 mg/dL [2.80 mmol/L] or >11.2 mg/dL [2.80 mmol/L]). The primary end point was achievement of a mean corrected total serum calcium value<10.2 mg/dL (2.55 mmol/L) during the efficacy period. The two key secondary end points were percent change in bone mineral density (BMD) at the femoral neck and absolute change in phosphorus; 78.9% cinacalcet- versus 3.5% placebo-treated subjects achieved the primary end point with a difference of 75.4% (95% confidence interval [CI]: 63.8, 87.1), p<0.001. There was no statistical difference in the percent change in BMD at the femoral neck between cinacalcet and placebo groups, p=0.266. The difference in the change in phosphorus between the two arms was 0.45 mg/dL (95% CI: 0.26, 0.64), p<0.001 (nominal). No new safety signals were detected. In conclusion, hypercalcemia and hypophosphatemia were effectively corrected after treatment with cinacalcet in patients with persistent HPT after KTx.

Cinacalcet for hypercalcaemic secondary hyperparathyroidism after renal transplantation: a multicentre, retrospective, 3-year study

AIMS

Our aim was to evaluate the long-term effect of cinacalcet in patients with hypercalcaemic secondary hyperparathyroidism (SHPT) after renal transplantation (RT) in order to expand real-world data in this population.

METHODS

We performed a multicentre, observational, retrospective study in 17 renal transplant units from Spain. We collected data from renal recipients with hypercalcaemic (calcium >10.2 mg/dL) SHPT (intact parathyroid hormone (iPTH) > 120 pg/mL) who initiated cinacalcet in the clinical practice.

RESULTS

We included 193 patients with a mean (standard deviation (SD)) age of 52 (12) years, 58% men. Cinacalcet treatment was initiated at a median of 20 months after RT (median dose 30 mg/day). Mean calcium levels decreased from a mean (SD) of 11.1 (0.6) at baseline to 10.1 (0.8) at 6 months (9.0% reduction, P < 0.0001). Median iPTH was reduced by 23.0% at 6 months (P = 0.0005) and mean phosphorus levels increased by 11.1% (P < 0.0001). The effects were maintained up to 3-years. No changes were observed in renal function or anticalcineurin drug levels. Only 4.1% of patients discontinued cinacalcet due to intolerance and 1.0% due to lack of efficacy.

CONCLUSIONS

In renal transplant patients with hypercalcaemic SHPT, cinacalcet controlled serum calcium, iPTH and phosphorus levels up to 3 years. Tolerability was good.

Withdrawal of cinacalcet at the time of renal transplantation is not a risk factor for allograft calcifications in the early posttransplantation period

BACKGROUND

Secondary hyperparathyroidism is a relevant problem in patients on dialysis. Cinacalcet in regular clinical practice increases the percentage of patients achieving treatment targets for PTH, Ca and P. We evaluated allograft calcification in serial protocol biopsies after transplantation among patients receiving Cinacalcet on dialysis but discontinued after surgery.

METHODS

This retrospective single-centre study included kidney allograft recipients who were receiving Cinacalcet for more than 6 months before surgery and had it withdrawn thereafter. The 46 patients including 17 women showed a mean overall age of 54 ± 30 years. Protocol graft biopsy was performed at 3 and at 12 months. Biochemical analyses at the time of biopsy included blood levels of creatinine, phosphorus, calcium, alkaline phosphatases, iPTH, and proteinuria.

RESULTS

Any biopsy showed nephrocalcinosis either intratubular calcifications, or in the parenchyma. There were no changes in calcemia (10.22 ± 0.7 to 10.27 ± 0.7 mg/dL), in alkaline phosphatase (259 ± 119.6 to 255 ± 122.3 mg/dL) nor in iPTH (317 ± 220.2 to 320 ± 168.8 pg/mL) between 3 and 12 months respectively. There was a slight but non-significant increase in serum phosphorus (2.79 ± 0.8 to 3.22 ± 0.9 mg/dL), serum creatinine (1.53 ± 0.6 to 1.84 ± 1.2 mg/dL) and proteinuria (528 ± 603 to 879 ± 1398 mg/24h) between 3 and 12 months respectively.

CONCLUSIONS

Withdrawal of Cinacalcet at the time of renal transplantation was not a risk factor for allograft calcifications in the early post-transplant period.

Mineral metabolism in renal transplant recipients discontinuing cinacalcet at the time of transplantation: a prospective observational study

BACKGROUND

The calcimimetic cinacalcet is approved for treating secondary hyperparathyroidism in patients with chronic kidney disease on dialysis. Biochemical profiles and clinical outcomes in patients discontinuing cinacalcet at the time of transplantation are scarce.

METHODS

We performed a prospective observational cohort study, including 303 incident renal transplant recipients, of whom 21 were on cinacalcet treatment at the time of transplantation. Parameters of mineral metabolism and incidence of parathyroidectomy and nephrocalcinosis in patients discontinuing cinacalcet at the time of transplantation patients ("cinacalcet +") were compared to cinacalcet-naïve patients ("cinacalcet -"). Mean follow-up was 35.6 ± 15.8 months.

RESULTS

At the time of transplantation, parameters of mineral metabolism were similar in both groups. Conversely, at month 3, serum ionized calcium (p = 0.0007), calcitriol (p = 0.02), biointact parathyroid hormone (p = 0.06) levels and urinary fractional excretion of phosphorus (p = 0.06) were higher, while serum phosphorus levels (p = 0.06) were lower in "cinacalcet +." Analysis based on matching at the time of initiation showed that the course of post-transplant mineral metabolism in cinacalcet-treated patients (median treatment period 12.5 months) vs. cinacalcet-naïve patients was identical. "Cinacalcet +" patients are characterized by a high-incidence proportion of both post-transplant nephrocalcinosis (45% at month 3) and parathyroidectomy (28.6%). No difference in renal function was observed between "cinacalcet +" and "cinacalcet-" patients.

CONCLUSION

Cinacalcet does not affect the course of secondary hyperparathyroidism in patients awaiting kidney transplantation. Biochemical profiles and a high parathyroidectomy rate suggest rebound hyperparathyroidism in renal transplant recipients discontinuing cinacalcet at the time of transplantation, which may be related to the short exposure time specific to this population. Risk/benefit studies are urgently required to define the role of continued calcimimetic treatment in renal transplant recipients and to determine the optimal treatment of secondary hyperparathyroidism in patients listed for transplantation.

Cinacalcet improves bone density in post-kidney transplant hyperparathyroidism

The recent availability of cinacalcet has provided a possible alternative to parathyroidectomy in kidney transplant patients with persistent hyperparathyroidism, but its effect on bone mass density (BMD) is unknown. From our database containing 163 kidney transplants performed at our center from 1999 to 2007, we compared recipients who received cinacalcet for persistent hypercalcemia and hyperparathyroidism following renal transplantation (n = 8) with up to two other posttransplant patients matched for age, sex, race, and graft function (n = 15). The outcome of the study was BMD changes from baseline to 12, 24, and 36 months post-renal transplantation. Repeated-measures mixed model was used to assess the difference of BMD change between two groups. Cinacalcet therapy was started at a median of 9 (range = 1 to 24) months posttransplant with a mean dose 56 ± 29 mg/d (mean duration = 1.6; range = 1 to 2.1 years). Cinacalcet therapy was associated with significant reduction of serum calcium compared to control. Cinacalcet therapy was associated with greater BMD increase at the hip over the 36-month posttransplant period. Cinacalcet was well tolerated. Our results suggest that cinacalcet may have a small but favorable effect on bone density following kidney transplantation.