Disorders of mineral metabolism, including secondary hyperparathyroidism, are thought to contribute to extraskeletal (including vascular) calcification among patients with chronic kidney disease. It has been hypothesized that treatment with the calcimimetic agent cinacalcet might reduce the risk of death or nonfatal cardiovascular events in such patients.
- Journal of the American Society of Nephrology : JASN
- Published over 3 years ago
Fractures are frequent in patients receiving hemodialysis. We tested the hypothesis that cinacalcet would reduce the rate of clinical fractures in patients receiving hemodialysis using data from the Evaluation of Cinacalcet HCl Therapy to Lower Cardiovascular Events trial, a placebo-controlled trial that randomized 3883 hemodialysis patients with secondary hyperparathyroidism to receive cinacalcet or placebo for ≤64 months. This study was a prespecified secondary analysis of the trial whose primary end point was all-cause mortality and non-fatal cardiovascular events, and one of the secondary end points was first clinical fracture event. Clinical fractures were observed in 255 of 1935 (13.2%) patients randomized to placebo and 238 of 1948 (12.2%) patients randomized to cinacalcet. In an unadjusted intention-to-treat analysis, the relative hazard for fracture (cinacalcet versus placebo) was 0.89 (95% confidence interval [95% CI], 0.75 to 1.07). After adjustment for baseline characteristics and multiple fractures, the relative hazard was 0.83 (95% CI, 0.72 to 0.98). Using a prespecified lag-censoring analysis (a measure of actual drug exposure), the relative hazard for fracture was 0.72 (95% CI, 0.58 to 0.90). When participants were censored at the time of cointerventions (parathyroidectomy, transplant, or provision of commercial cinacalcet), the relative hazard was 0.71 (95% CI, 0.58 to 0.87). Fracture rates were higher in older compared with younger patients and the effect of cinacalcet appeared more pronounced in older patients. In conclusion, using an unadjusted intention-to-treat analysis, cinacalcet did not reduce the rate of clinical fracture. However, when accounting for differences in baseline characteristics, multiple fractures, and/or events prompting discontinuation of study drug, cinacalcet reduced the rate of clinical fracture by 16%-29%.
The IMPACT SHPT [Improved Management of Intact Parathyroid Hormone (iPTH) with Paricalcitol-Centered Therapy Versus Cinacalcet Therapy with Low-Dose Vitamin D in Hemodialysis Patients with Secondary Hyperparathyroidism] study compared the effectiveness of paricalcitol and cinacalcet in the management of secondary hyperparathyroidism in haemodialysis patients but did not report the costs or cost effectiveness of these treatments.
The calcimimetic cinacalcet is used to treat secondary hyperparathyroidism in patients receiving dialysis, and asymptomatic hypocalcemia is often observed following its initiation. Here we investigated the incidence, predictors and therapeutic consequences of hypocalcemia by a post hoc analysis of the randomized, double-blind, placebo-controlled EValuation Of Cinacalcet Hydrochloride Therapy to Lower CardioVascular Events (EVOLVE) trial. Hypocalcemia was classified as mild (total serum calcium 8.0-8.39 mg/dL), moderate (7.5-7.99 mg/dL) or severe (under 7.5 mg/dL). At least one episode of hypocalcemia developed within 16 weeks after the first administered dose among 58.3% of 1938 patients randomized to cinacalcet versus 14.9% of 1923 patients randomized to placebo. Hypocalcemia in the cinacalcet group was severe in 18.4% of the patients versus 4.4% in the placebo group. Severe hypocalcemia following administration of cinacalcet was associated with higher baseline plasma parathyroid hormone, lower corrected total serum calcium, higher serum alkaline phosphatase, geographic region (patients from Latin America and Russia had a higher risk relative to the United States) and higher body mass index. The median cinacalcet dose immediately prior to the first hypocalcemic episode was 54-58 mg/day and similar in the three hypocalcemia categories. In the majority of patients, hypocalcemia resolved spontaneously within 14 days without modification of background therapy. Among patients who received an intervention, the most common was an increase in the active vitamin D sterol dose. Thus, the occurrence of hypocalcemia is frequent following initiation of cinacalcet and the likelihood of developing hypocalcemia was related to the severity of secondary hyperparathyroidism. Hypocalcemia was generally asymptomatic and self-limited.
Evaluation of bone is of great importance in chronic kidney disease patients, as these patients are at an increased risk for fractures. We treated a hemodialysis patient suffering from hyperparathyroid bone disease with cinacalcet hydrochloride and concurrent administration of maxacalcitol and alfacalcidol for a year. Hyperparathyroid bone disease is characterized by cortical thinning, increased cortical porosity, reduced trabecular bone volume, and increased hypomineralized matrix volume, and there is little information to date about the effects of treatment with cinacalcet hydrochloride on the bone fragility in patients with hyperparathyroid bone disease. In the present study, histological and backscattered electron microscopic evaluation of this combination treatment revealed an excellent improvement of both bone volume and bone morphology. This treatment improved cortical thinning, cortical porosity, and trabecular thinning. Furthermore, the treatment also reduced hypomineralized matrix volume, indicative of improved mineralization by osteocytes. We speculate that the intermittent maxacalcitol administration may have effectively stimulated the vitamin D receptors expressed on osteocytes and osteoblasts, resulting in increased mineralization. Our approach for evaluating the bone in patients with chronic kidney disease by backscattered electron microscopy is novel.
Etelcalcetide is a novel intravenous calcimimetic for the treatment of secondary hyperparathyroidism (SHPT) in haemodialysis patients. The clinical efficacy and safety of etelcalcetide (in addition to phosphate binders and vitamin D and/or analogues [PB/VD]) was evaluated in three phase III studies, including two placebo-controlled trials and a head-to-head study versus the oral calcimimetic cinacalcet.
To assess the efficacy and safety of cinacalcet on secondary hyperparathyroidism in patients with chronic kidney disease, Pubmed, Embase, and the Cochrane Central Register of Controlled Trials were searched until March 2016. Trial sequential analysis (TSA) was conducted to control the risks of type I and II errors and calculate required information size (RIS). A total of 25 articles with 8481 participants were included. Compared with controls, cinacalcet administration did not reduce all-cause mortality (RR = 0.97, 95% CI = 0.89-1.05, P = 0.41, TSA-adjusted 95% CI = 0.86-1.08, RIS = 5260, n = 8386) or cardiovascular mortality (RR = 0.95, 95% CI = 0.83-1.07, P = 0.39, TSA-adjusted 95% CI = 0.70-1.26, RIS = 3780 n = 5418), but it reduced the incidence of parathyroidectomy (RR = 0.48, 95% CI = 0.40-0.50, P < 0.001, TSA-adjusted 95% CI = 0.39-0.60, RIS = 5787 n = 5488). Cinacalcet increased the risk of hypocalcemia (RR = 8.48, 95% CI = 6.37-11.29, P < 0.001, TSA-adjusted 95% CI = 5.25-13.70, RIS = 6522, n = 7785), nausea (RR = 2.12, 95% CI = 1.62-2.77, P < 0.001, TSA-adjusted 95% CI = 1.45-3.04, RIS = 4684, n = 7512), vomiting (RR = 2.00, 95% CI = 1.79-2.24, P < 0.001, TSA-adjusted 95% CI = 1.77-2.26, RIS = 1374, n = 7331) and diarrhea (RR = 1.17, 95% CI = 1.05-1.32, P = 0.006, TSA-adjusted 95% CI = 1.02-1.36, RIS = 8388, n = 6116). Cinacalcet did not significantly reduce the incidence of fractures (RR = 0.58, 95% CI = 0.21-1.59, P = 0.29, TSA-adjusted 95% CI = 0.01-35.11, RIS = 76376, n = 4053). Cinacalcet reduced the incidence of parathyroidectomy, however, it did not reduce all-cause and cardiovascular mortality, and increased the risk of adverse events including hypocalcemia and gastrointestinal disorders.
We evaluated the improvement of intact parathyroid hormone (iPTH) levels and bone parameters by supplementing nutritional vitamin D (cholecalciferol) to combined calcimimetic (cinacalcet) and active vitamin D analog (calcitriol) among severe secondary hyperparathyroidism (SHPT) hemodialysis (HD) patients. A randomized, controlled open-label study was undertaken in 60 HD patients with serum iPTH > 1000 pg/mL or persistently high iPTH ≥ 600 pg/mL even after >3 months of calcitriol (3 μg/week). The study group received oral cholecalciferol (5000 IU/ day) and the control group received a placebo. All patients received fixed dose cinacalcet (30 mg/day, orally) and calcitriol. Calcitriol was reduced if iPTH ≤ 300 pg/mL and cinacalcet was withdrawn if serum iPTH was persistently low (iPTH ≤ 300 pg/mL) for 4 weeks after the reduction of calcitriol. A significantly lower iPTH level was noted from the 20th week in the study group compared to the placebo group, and the target iPTH ≤ 300 pg/mL was achieved at the 24th week in the study group. Most patients achieved serum 25-(OH)D₃ ≥ 30 ng/mL in the study group. Nearly 40% of study patients gained >10% improvement in femoral neck (FN) bone mineral density (BMD). We conclude that cholecalciferol additively reduced serum iPTH levels, improved 25-(OH)D₃ levels and improved FN BMD when used together with cinacalcet/calcitriol in severe SHPT HD patients.
Mutations of the sigma subunit of the heterotetrameric adaptor-related protein complex 2 (AP2σ) impair signalling of the calcium-sensing receptor (CaSR), and cause familial hypocalciuric hypercalcaemia type 3 (FHH3). To date, FHH3-associated AP2σ mutations have only been identified at one residue, Arg15. We hypothesized that additional rare AP2σ variants may also be associated with altered CaSR function and hypercalcaemia, and sought for these by analysing >111,995 exomes (>60,706 from ExAc and dbSNP, and 51,289 from the Geisinger Health System-Regeneron DiscovEHR dataset which also contains clinical data). This identified 11 individuals to have 9 non-synonymous AP2σ variants (Arg3His, Arg15His (x3), Ala44Thr, Phe52Tyr, Arg61His, Thr112Met, Met117Ile, Glu122Gly, Glu142Lys) with 3 of the 4 individuals who had Arg15His and Met117Ile AP2σ variants having mild hypercalcaemia, thereby indicating a prevalence of FHH3-associated AP2σ mutations of ∼7.8 per 100,000 individuals. Structural modelling of the novel 8 AP2σ variants (Arg3His, sAla44Thr, Phe52Tyr, Arg61His, Thr112Met, Met117Ile, Glu122Gly and Glu142Lys) predicted that the Arg3His, Thr112Met, Glu122Gly and Glu142Lys AP2σ variants would disrupt polar contacts within the AP2σ subunit or affect the interface between the AP2σ and AP2α subunits. Functional analyses of all 8 AP2σ variants in CaSR-expressing cells demonstrated that the Thr112Met, Met117Ile and Glu142Lys variants, located in the AP2σ α4-α5 helical region that forms an interface with AP2α, impaired CaSR-mediated intracellular calcium (Cai2+) signalling, consistent with a loss-of-function, and this was rectified by treatment with the CaSR positive allosteric modulator cinacalcet. Thus, our studies demonstrate another potential class of FHH3-causing AP2σ mutations located at the AP2σ-AP2α interface.
Secondary hyperparathyroidism (SHPT) is a rare complication of furosemide therapy that can occur in patients treated with the loop diuretic for a long period of time. We report a 6-month-old 28-weeks premature infant treated chronically with furosemide for his bronchopulmonary dysplasia, who developed hypocalcemia and severe SHPT, adversely affecting his bones. Discontinuation of the loop diuretic and the addition of supplemental calcium and calcitriol only partially reversed the SHPT, bringing serum parathyroid hormone level down from 553 to 238 pg/mL. After introduction of the calcimimetic Cinacalcet, we observed a sustained normalization of parathyroid hormone concentration at 27 to 63 pg/mL and, with that correction, of all biochemical abnormalities and healing of the bone disease. No adverse effects were noted. We conclude that in cases of SHPT due to furosemide in which traditional treatment fails, there may be room to consider the addition of a calcimimetic agent.