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Cernaro V, Longhitano E, Casuscelli C, Peritore L, Santoro D. Hyperphosphatemia in Chronic Kidney Disease: The Search for New Treatment Paradigms and the Role of Tenapanor. Int J Nephrol Renovasc Dis 2024; 17:151-161. [PMID: 38831770 PMCID: PMC11144652 DOI: 10.2147/ijnrd.s385826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 05/14/2024] [Indexed: 06/05/2024] Open
Abstract
Hyperphosphataemia represents a significant challenge in the management of chronic kidney disease, exerting a pronounced influence on the pathogenesis of cardiovascular complications and mineral bone disorders. Traditional approaches to address hyperphosphataemia involve implementing dietary phosphate restrictions, administering phosphate binders, and, in cases of end-stage renal disease, resorting to dialysis. Unfortunately, these interventions frequently prove inadequate in maintaining phosphate levels within recommended ranges. Additionally, commonly employed pharmacological agents are not immune to eliciting adverse events, thereby limiting their prescription and therapeutic adherence. There is a growing focus on exploring novel therapeutic strategies in this context. The current discussion centres on tenapanor, a pharmacological agent predominantly acting as a selective inhibitor of sodium/hydrogen exchanger isoform 3 (NHE3). Its mechanism of action involves modulating tight junctions, resulting in reduced sodium absorption and intestinal paracellular permeability to phosphate. Furthermore, tenapanor downregulates sodium-dependent phosphate 2b transport protein (NaPi2b) expression, thereby impeding active transcellular phosphate transport. Clinical trials have elucidated the efficacy and safety profile of tenapanor. This evidence hints at a potential paradigm shift in the management of hyperphosphataemia. However, the burgeoning optimism surrounding tenapanor warrants tempered enthusiasm, as further research remains indispensable. The imperative lies in meticulously delineating its efficacy and safety contours within the crucible of clinical practice. In this review, we synthesize the intricate interplay between hyperphosphataemia and Chronic Kidney Disease-Mineral Bone Disorder, and we discuss the existing pharmacological interventions for hyperphosphataemia and explore emerging treatment paradigms that offer novel perspectives in managing elevated phosphate levels in CKD patients.
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Affiliation(s)
- Valeria Cernaro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Elisa Longhitano
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Chiara Casuscelli
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Luigi Peritore
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Domenico Santoro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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Edmonston D, Grabner A, Wolf M. FGF23 and klotho at the intersection of kidney and cardiovascular disease. Nat Rev Cardiol 2024; 21:11-24. [PMID: 37443358 DOI: 10.1038/s41569-023-00903-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/15/2023]
Abstract
Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). As CKD progresses, CKD-specific risk factors, such as disordered mineral homeostasis, amplify traditional cardiovascular risk factors. Fibroblast growth factor 23 (FGF23) regulates mineral homeostasis by activating complexes of FGF receptors and transmembrane klotho co-receptors. A soluble form of klotho also acts as a 'portable' FGF23 co-receptor in tissues that do not express klotho. In progressive CKD, rising circulating FGF23 levels in combination with decreasing kidney expression of klotho results in klotho-independent effects of FGF23 on the heart that promote left ventricular hypertrophy, heart failure, atrial fibrillation and death. Emerging data suggest that soluble klotho might mitigate some of these effects via several candidate mechanisms. More research is needed to investigate FGF23 excess and klotho deficiency in specific cardiovascular complications of CKD, but the pathophysiological primacy of FGF23 excess versus klotho deficiency might never be precisely resolved, given the entangled feedback loops that they share. Therefore, randomized trials should prioritize clinical practicality over scientific certainty by targeting disordered mineral homeostasis holistically in an effort to improve cardiovascular outcomes in patients with CKD.
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Affiliation(s)
- Daniel Edmonston
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
| | - Alexander Grabner
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA.
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA.
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Silva AL, Chertow GM, Hernandez GT, Lynn RI, Tietjen DP, Rosenbaum DP, Yang Y, Edelstein S. Tenapanor Improves Long-Term Control of Hyperphosphatemia in Patients Receiving Maintenance Dialysis: the NORMALIZE Study. KIDNEY360 2023; 4:1580-1589. [PMID: 37853560 PMCID: PMC10695649 DOI: 10.34067/kid.0000000000000280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 10/11/2023] [Indexed: 10/20/2023]
Abstract
Key Points Tenapanor is a first-in-class, minimally systemic sodium–hydrogen exchanger 3 inhibitor with a mechanism of action distinct from phosphate binders. Tenapanor alone or with phosphate binders led to 35%–49% of patients achieving serum phosphate ≤4.5 mg/dl over an 18-month period versus 22% at baseline. Tenapanor alone or with phosphate binders may help adults with CKD on maintenance dialysis achieve normal serum phosphate concentrations. Background Most patients with ESKD and hyperphosphatemia have difficulty controlling serum phosphate (sP) concentrations despite maintenance dialysis, dietary restriction, and phosphate binder treatment. NORMALIZE evaluated the efficacy and safety of tenapanor 30 mg twice daily alone or in combination with phosphate binders to achieve sP within the adult population reference range (2.5–4.5 mg/dl). Methods Patients who completed the Phase 3 PHREEDOM study could enroll in NORMALIZE. Patients enrolled in NORMALIZE who had received tenapanor during the PHREEDOM study (n =111) added sevelamer carbonate if sP was >4.5 mg/dl. Patients who had received sevelamer carbonate during the PHREEDOM study (n =61) added tenapanor and decreased sevelamer carbonate if sP was ≤4.5 mg/dl, per protocol titration schedule. Patients were followed in NORMALIZE for up to 18 months. We assessed efficacy in the full analysis set, defined as patients who received ≥1 dose of study drug and had ≥1 post-treatment sP measurement (n =171). We assessed safety in all patients who received ≥1 dose of study drug (n =172). Results At the end point visit, 57 of 171 patients (33%) in the full analysis set achieved sP between 2.5 and 4.5 mg/dl. Eight of 23 patients (35%) who were on tenapanor alone at the end point visit achieved sP between 2.5 and 4.5 mg/dl. The mean reduction from PHREEDOM baseline to end of NORMALIZE in sP was 2.0 mg/dl. Serum intact fibroblast growth factor-23 was significantly reduced; serum intact parathyroid hormone was significantly reduced among patients with intact parathyroid hormone ≥300 pg/ml at PHREEDOM baseline. The most commonly reported treatment-emergent adverse event was diarrhea in 38 of 172 patients (22%), which led to tenapanor discontinuation in four patients (2%). Conclusions Tenapanor alone or in combination with phosphate binders helped adult patients on maintenance dialysis achieve normal sP concentrations. Safety was consistent with previous studies of tenapanor. Clinical trial registry name and registration number A Long-Term Study to Evaluate the Ability of Tenapanor Alone or in Combination With Sevelamer to Treat to Goal Serum Phosphorus in Patients With ESKD on Dialysis (NORMALIZE), NCT03988920 .
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Affiliation(s)
| | - Glenn M. Chertow
- Departments of Medicine and Epidemiology and Population Health, Stanford University School of Medicine, Stanford, California
| | | | | | | | | | - Yang Yang
- Ardelyx, Inc., Waltham, Massachusetts
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Egli-Spichtig D, Hamid AK, Arroyo EMP, Ketteler M, Wiecek A, Rosenkranz AR, Pasch A, Lorenz H, Hellmann B, Karus M, Ammer R, Rubio-Aliaga I, Wagner CA. Intact FGF23 predicts serum phosphate improvement after combined nicotinamide and phosphate binder treatment in hemodialysis patients. Clin Kidney J 2023; 16:1622-1633. [PMID: 37779856 PMCID: PMC10539220 DOI: 10.1093/ckj/sfad040] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Indexed: 10/03/2023] Open
Abstract
Background Hyperphosphatemia is associated with increased mortality and cardiovascular morbidity of end-stage kidney failure (ESKF) patients. Managing serum phosphate in ESKF patients is challenging and mostly based on limiting intestinal phosphate absorption with low phosphate diets and phosphate binders (PB). In a multi-centric, double-blinded, placebo-controlled study cohort of maintenance hemodialysis patients with hyperphosphatemia, we demonstrated the efficacy of nicotinamide modified release (NAMR) formulation treatment in addition to standard PB therapy in decreasing serum phosphate. Here we aimed to assess the relationship between phosphate, FGF23, inflammation and iron metabolism in this cohort. Methods We measured the plasma concentrations of intact fibroblast growth factor 23 (iFGF23) and selected proinflammatory cytokines at baseline and Week 12 after initiating treatment. Results We observed a strong correlation between iFGF23 and cFGF23 (C-terminal fragment plus iFGF23). We identified iFGF23 as a better predictor of changes in serum phosphate induced by NAMR and PB treatment compared with cFGF23. Recursive partitioning revealed at baseline and Week 12, that iFGF23 and cFGF23 together with T50 propensity were the most important predictors of serum phosphate, whereas intact parathyroid hormone (iPTH) played a minor role in this model. Furthermore, we found serum phosphate and iPTH as the best predictors of iFGF23 and cFGF23. Sex, age, body mass index, and markers of inflammation and iron metabolism had only a minor impact in predicting FGF23. Conclusion Lowering serum phosphate in ESKF patients may depend highly on iFGF23 which is correlated to cFGF23 levels. Serum phosphate was the most important predictor of plasma FGF23 in this ESKF cohort.
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Affiliation(s)
- Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Eva Maria Pastor Arroyo
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Markus Ketteler
- Robert Bosch Hospital, Department of General Internal Medicine and Nephrology, Stuttgart, Germany
| | - Andrzej Wiecek
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Katowice, Poland
| | - Alexander R Rosenkranz
- Division of Nephrology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Andreas Pasch
- Calciscon AG, 2503 Biel, Switzerland
- Department of Nephrology, Lindenhofspital, 3012 Bern, Switzerland
- Department of Physiology and Pathophysiology, Johannes Kepler University Linz, Linz, Austria
| | - Horst Lorenz
- Buero fuer Biometrie und Statistik, Neuberg, Germany
| | | | - Michael Karus
- MEDICE Arzneimittel Pütter GmbH & Co KG, Iserlohn, Germany
| | - Richard Ammer
- MEDICE Arzneimittel Pütter GmbH & Co KG, Iserlohn, Germany
- Department of Medicine D, Division of General Internal Medicine, Nephrology and Rheumatology, University Hospital of Münster, Münster, Germany
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
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Magagnoli L, Cozzolino M, Galassi A. The open system of FGF-23 at the crossroad between additional P-lowering therapy, anemia and inflammation: how to deal with the intact and the C-terminal assays? Clin Kidney J 2023; 16:1543-1549. [PMID: 37779858 PMCID: PMC10539210 DOI: 10.1093/ckj/sfad144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Indexed: 10/03/2023] Open
Abstract
Fibroblast growth factor 23 (FGF-23) has been associated with increased cardiovascular risk and poor survival in dialysis patients. It is well established that FGF-23 synthesis is directly induced by positive phosphate (P) balance. On the other hand, P-lowering treatments such as nutritional P restriction, P binders and dialysis are capable of reducing FGF-23 levels. However, there are many uncertainties regarding the possibility of adopting FGF-23 to guide the clinical decision-making process in the context of chronic kidney disease-mineral bone disorder (CKD-MBD). Furthermore, the best assay to adopt for measurement of FGF-23 levels (namely the intact vs the C-terminal one) remains to be determined, especially in conditions capable of altering the synthesis as well as the cleavage of the intact and biologically active molecule, as occurs in the presence of CKD and its complications. This Editorial discusses the main insights provided by the post hoc analysis of the NOPHOS trial, with particular attention given to evidence-based peculiarities of the intact and the C-terminal assays available for measuring FGF-23 levels, especially in patients receiving additive P-lowering therapy in the presence of inflammation, anemia and iron deficiency.
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Affiliation(s)
- Lorenza Magagnoli
- University of Milan, Department of Health Sciences, Milano, Italy
- ASST Santi Paolo e Carlo, Renal Division, Milano, Italy
| | - Mario Cozzolino
- University of Milan, Department of Health Sciences, Milano, Italy
- ASST Santi Paolo e Carlo, Renal Division, Milano, Italy
| | - Andrea Galassi
- University of Milan, Department of Health Sciences, Milano, Italy
- ASST Santi Paolo e Carlo, Renal Division, Milano, Italy
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Vergaro G, Del Franco A, Aimo A, Gentile F, Castiglione V, Saponaro F, Masotti S, Prontera C, Fusari N, Emdin M, Passino C. Intact fibroblast growth factor 23 in heart failure with reduced and mildly reduced ejection fraction. BMC Cardiovasc Disord 2023; 23:433. [PMID: 37658340 PMCID: PMC10474676 DOI: 10.1186/s12872-023-03441-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 08/09/2023] [Indexed: 09/03/2023] Open
Abstract
BACKGROUND Fibroblast growth factor-23 (FGF23) has been associated to left ventricular (LV) hypertrophy and heart failure (HF) severity. We aimed to investigate the clinical correlates and prognostic value of intact FGF23 (iFGF23) in HF patients. METHODS Patients with stable HF and left ventricular ejection fraction (LVEF) < 50% were prospectively enrolled, managed according to current recommendations and followed over time. iFGF23 was measured at baseline with a fully automated immuno-chemiluminescent assay. RESULTS We enrolled 150 patients (82% males; median age 65 years). First, second, and third iFGF23 tertiles were < 35.2 pg/mL, 35.2-50.9 pg/mL, and > 50.9 pg/mL. LVEF decreased from the first iFGF23 tertile to the third tertile (p = 0.014). N-terminal pro-B-type natriuretic peptide (NT-proBNP) increased from the first to the third tertile (p = 0.001), while peak oxygen consumption decreased (p < 0.001). Thirty-five patients (23%) experienced the primary endpoint (all-cause death or HF hospitalization at 5 years), and 26 (17%) the secondary endpoint (all-cause death at 5 years). On multivariable analysis, iFGF23 independently predicted the primary endpoint on top of age, gender and LVEF (HR 4.6 [95% CI 2.1-10.3], p < 0.001), age, gender and eGFR (HR 4.1 [95% CI 1.6-10.3], p = 0.003), as well as age, gender and NT-proBNP (HR 3.6 [95% CI 1.6-8.2], p = 0.002). iFGF23 even reclassified patient risk on top of all the 3 models, with NRI values of 0.65 (95% CI 0.30-1.01), 0.55 (95% CI 0.25-0.88), and 0.60 (95% CI 0.24-0.96), respectively (both p < 0.001). CONCLUSIONS Circulating iFGF23 is associated with disease severity and outcome in HF patients with reduced and mildly reduced ejection fraction.
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Affiliation(s)
- Giuseppe Vergaro
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy.
- Health Science Interdisciplinary Center , Scuola Superiore Sant'Anna, Pisa, Italy.
| | - Annamaria Del Franco
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
- Health Science Interdisciplinary Center , Scuola Superiore Sant'Anna, Pisa, Italy
| | - Alberto Aimo
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
- Health Science Interdisciplinary Center , Scuola Superiore Sant'Anna, Pisa, Italy
| | - Francesco Gentile
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
| | - Vincenzo Castiglione
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
| | | | - Silvia Masotti
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
| | - Concetta Prontera
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
| | - Niccolò Fusari
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
| | - Michele Emdin
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
- Health Science Interdisciplinary Center , Scuola Superiore Sant'Anna, Pisa, Italy
| | - Claudio Passino
- Division of Cardiology and Cardiovascular Medicine, Fondazione Toscana Gabriele Monasterio, Via Moruzzi, 1, Pisa, 56127, Italy
- Health Science Interdisciplinary Center , Scuola Superiore Sant'Anna, Pisa, Italy
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Cernaro V, Longhitano E, Calabrese V, Casuscelli C, Di Carlo S, Spinella C, Gembillo G, Santoro D. Progress in pharmacotherapy for the treatment of hyperphosphatemia in renal failure. Expert Opin Pharmacother 2023; 24:1737-1746. [PMID: 37527180 DOI: 10.1080/14656566.2023.2243817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/03/2023]
Abstract
INTRODUCTION Among the clinical and metabolic complications of progressive chronic kidney disease (CKD), CKD-mineral bone disorder (CKD-MBD) significantly contributes to morbidity and mortality. While overt and persistent hyperphosphatemia is typical of advanced CKD and requires treatment, other abnormalities of calcium/phosphate metabolism begin to occur since the early stages of the disease. AREAS COVERED We searched on the PubMed database, without restrictions for language or time range, for randomized clinical trials and meta-analyses investigating phosphate-lowering therapies. The various phosphate binders show different safety profiles and diverse effects on calcium/phosphate metabolism and vascular calcification. The in-depth knowledge of the characteristics of these drugs is crucial to ensure adequate treatment to CKD patients. EXPERT OPINION A proper control of serum phosphate can be achieved using phosphate binders. These medications may induce side effects. Moreover, data on their impact on clinical outcomes are partly controversial or scarce, especially for the new generation drugs. Hyperphosphatemia favors cardiovascular disease and increases the risk for CKD progression. These effects are partially mediated by fibroblast growth factor 23 (FGF23), a phosphaturic hormone that raises to maintain normal serum phosphate. Since there are no data supporting the use of phosphate-lowering agents when phosphataemia is normal, a key role is played by reducing dietary phosphate intake with the aim to control serum phosphate and the compensatory FGF23 and parathyroid hormone (PTH) increase.
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Affiliation(s)
- Valeria Cernaro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Elisa Longhitano
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Vincenzo Calabrese
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Chiara Casuscelli
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Silvia Di Carlo
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Claudia Spinella
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Guido Gembillo
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Domenico Santoro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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Xue J, Thomas L, Murali SK, Levi M, Fenton RA, Dominguez Rieg JA, Rieg T. Enhanced phosphate absorption in intestinal epithelial cell-specific NHE3 knockout mice. Acta Physiol (Oxf) 2022; 234:e13756. [PMID: 34978760 PMCID: PMC9286053 DOI: 10.1111/apha.13756] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/16/2021] [Accepted: 01/01/2022] [Indexed: 12/11/2022]
Abstract
Aims The kidneys play a major role in maintaining Pi homeostasis. Patients in later stages of CKD develop hyperphosphatemia. One novel treatment option is tenapanor, an intestinal‐specific NHE3 inhibitor. To gain mechanistic insight into the role of intestinal NHE3 in Pi homeostasis, we studied tamoxifen‐inducible intestinal epithelial cell‐specific NHE3 knockout (NHE3IEC‐KO) mice. Methods Mice underwent dietary Pi challenges, and hormones as well as urinary/plasma Pi were determined. Intestinal 33P uptake studies were conducted in vivo to compare the effects of tenapanor and NHE3IEC‐KO. Ex vivo Pi transport was measured in everted gut sacs and brush border membrane vesicles. Intestinal and renal protein expression of Pi transporters were determined. Results On the control diet, NHE3IEC‐KO mice had similar Pi homeostasis, but a ~25% reduction in FGF23 compared with control mice. Everted gut sacs and brush border membrane vesicles showed enhanced Pi uptake associated with increased Npt2b expression in NHE3IEC‐KO mice. Acute oral Pi loading resulted in higher plasma Pi in NHE3IEC‐KO mice. Tenapanor inhibited intestinal 33P uptake acutely but then led to hyper‐absorption at later time points compared to vehicle. In response to high dietary Pi, plasma Pi and FGF23 increased to higher levels in NHE3IEC‐KO mice which was associated with greater Npt2b expression. Reduced renal Npt2c and a trend for reduced Npt2a expression were unable to correct for higher plasma Pi. Conclusion Intestinal NHE3 has a significant contribution to Pi homeostasis. In contrast to effects described for tenapanor on Pi homeostasis, NHE3IEC‐KO mice show enhanced, rather than reduced, intestinal Pi uptake.
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Affiliation(s)
- Jianxiang Xue
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
| | - Linto Thomas
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
| | | | - Moshe Levi
- Department of Biochemistry and Molecular & Cellular Biology Georgetown University Washington District of Columbia USA
| | | | - Jessica A. Dominguez Rieg
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
- James A. Haley Veterans' Hospital Tampa Florida USA
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
- James A. Haley Veterans' Hospital Tampa Florida USA
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Inaba M, Une Y, Ikejiri K, Kanda H, Fukagawa M, Akizawa T. Dose-Response of Tenapanor in Patients With Hyperphosphatemia Undergoing Hemodialysis in Japan—a Phase 2 Randomized Trial. Kidney Int Rep 2021; 7:177-188. [PMID: 35155857 PMCID: PMC8820999 DOI: 10.1016/j.ekir.2021.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 12/18/2022] Open
Abstract
Introduction Simplified, but effective, hyperphosphatemia treatments with novel mechanisms of action, tolerable safety profiles, and low pill burden are needed for patients undergoing hemodialysis. Tenapanor is a calcium (Ca)-free, nonmetal, nonpolymeric drug that reduces phosphate absorption by selectively inhibiting intestinal sodium-hydrogen exchanger 3. As the serum phosphorus (P) level-lowering effect of tenapanor has not been evaluated in Japanese patients with hyperphosphatemia undergoing hemodialysis, we evaluated its efficacy and safety in this population. Methods This was a multicenter, phase 2, double-blind, placebo-controlled, parallel-group, dose-finding study. Change in serum P level from baseline at week 6 was the primary end point. Results Overall, 207 patients were randomized to 5 groups (placebo [n = 41] and tenapanor 5-mg taken twice daily [BID] [n = 42], 10-mg BID [n = 41], 30-mg BID [n = 42], and 30-mg BID dose-titration [n = 41]) and treated for 6 weeks. Mean changes from baseline at week 6 in serum P level were 0.64, −0.93, −1.36, −1.92, and −1.99 mg/dl in the placebo and tenapanor groups, respectively. Serum P level was significantly decreased from baseline in all tenapanor groups compared with placebo (P < 0.001, for each dose). Diarrhea was the most frequent drug-related adverse event (AE) with an incidence of 9.8%, 50.0%, 65.9%, 76.2%, and 65.9% in the respective placebo and tenapanor groups. Conclusion In Japanese patients undergoing hemodialysis, tenapanor was found to have a dose-responsive, serum P level-lowering effect. Diarrhea was the most frequent drug-related AE; most cases were mild and generally tolerable. Tenapanor may become a first-in-class therapeutic agent for patients with hyperphosphatemia.
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Block GA, Bleyer AJ, Silva AL, Weiner DE, Lynn RI, Yang Y, Rosenbaum DP, Chertow GM. Safety and Efficacy of Tenapanor for Long-term Serum Phosphate Control in Maintenance Dialysis: A 52-Week Randomized Phase 3 Trial (PHREEDOM). KIDNEY360 2021; 2:1600-1610. [PMID: 35372979 PMCID: PMC8785778 DOI: 10.34067/kid.0002002021] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/25/2021] [Indexed: 12/17/2022]
Abstract
Background Treating hyperphosphatemia is a tenet of dialysis care. This trial assessed the safety and efficacy of tenapanor for the management of hyperphosphatemia. Methods In this 52-week phase 3 study (NCT03427125), participants receiving maintenance dialysis with both hyperphosphatemia (serum phosphate 6.0-10.0 mg/dl) and a 1.5 mg/dl increase after phosphate binder washout were randomized (3:1) to tenapanor 30 mg twice daily for 26 weeks (randomized treatment period) or sevelamer carbonate (52-week safety control). Participants completing 26 weeks of treatment with tenapanor were rerandomized (1:1) to tenapanor or placebo for 12 weeks (randomized withdrawal period), and were eligible to enter the 14-week safety extension period. With input from the US Food and Drug Administration, the primary efficacy end point was the difference in the change in serum phosphate from the end of the randomized treatment period to the end of the randomized withdrawal period, among participants who achieved ≥1.2 mg/dl decrease in serum phosphate during the randomized treatment period (efficacy analysis set). Efficacy was also evaluated in the intention-to-treat (ITT) analysis set. Results Of 564 eligible participants randomized to receive tenapanor (n=423) or sevelamer carbonate (n=141) during the randomized treatment period, 255 (60%) in the tenapanor group subsequently were rerandomized to tenapanor (n=128) or placebo (n=127) during the randomized withdrawal period. In the efficacy analysis set (n=131), the difference in estimated mean change in serum phosphate level between tenapanor and placebo from the beginning to the end of the randomized withdrawal period was -1.4 mg/dl (P<0.0001); in the ITT analysis set (n=243), the estimated mean difference was -0.7 mg/dl (P=0.002). Loosened stools were the most frequently reported adverse event (53% during the randomized treatment period). Serious adverse events were reported more frequently for participants treated with sevelamer carbonate (16%-23% across the three study periods) compared with tenapanor (11%-17%). Conclusions Tenapanor reduced serum phosphate concentrations and maintained control of serum phosphate in participants receiving maintenance dialysis, with an acceptable safety and tolerability profile.
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Affiliation(s)
- Geoffrey A Block
- Clinical Research and Medical Affairs, US Renal Care, Inc., Plano, Texas
| | - Anthony J Bleyer
- Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Arnold L Silva
- Boise Kidney and Hypertension Institute, Meridian, Idaho
| | - Daniel E Weiner
- Division of Nephrology, Tufts Medical Center, Boston, Massachusetts
| | - Robert I Lynn
- Department of Medicine, Albert Einstein College of Medicine, New York, New York.,Kidney Medical Associates, New York, New York
| | - Yang Yang
- Biometrics, Ardelyx, Inc., Fremont, California
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11
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Phosphate and fibroblast growth factor 23 in diabetes. Clin Sci (Lond) 2021; 135:1669-1687. [PMID: 34283205 PMCID: PMC8302806 DOI: 10.1042/cs20201290] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/11/2022]
Abstract
Diabetes is associated with a strongly elevated risk of cardiovascular disease, which is even more pronounced in patients with diabetic nephropathy. Currently available guideline-based efforts to correct traditional risk factors are only partly able to attenuate this risk, underlining the urge to identify novel treatment targets. Emerging data point towards a role for disturbances in phosphate metabolism in diabetes. In this review, we discuss the role of phosphate and the phosphate-regulating hormone fibroblast growth factor 23 (FGF23) in diabetes. We address deregulations of phosphate metabolism in patients with diabetes, including diabetic ketoacidosis. Moreover, we discuss potential adverse consequences of these deregulations, including the role of deregulated phosphate and glucose as drivers of vascular calcification propensity. Finally, we highlight potential treatment options to correct abnormalities in phosphate and FGF23. While further studies are needed to more precisely assess their clinical impact, deregulations in phosphate and FGF23 are promising potential target in diabetes and diabetic nephropathy.
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12
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Pergola PE, Rosenbaum DP, Yang Y, Chertow GM. A Randomized Trial of Tenapanor and Phosphate Binders as a Dual-Mechanism Treatment for Hyperphosphatemia in Patients on Maintenance Dialysis (AMPLIFY). J Am Soc Nephrol 2021; 32:1465-1473. [PMID: 33766811 PMCID: PMC8259655 DOI: 10.1681/asn.2020101398] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 01/30/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Hyperphosphatemia is associated with cardiovascular morbidity and mortality in patients receiving maintenance dialysis. It is unknown whether combining two therapies with different mechanisms of action-tenapanor, an inhibitor of paracellular phosphate absorption, and phosphate binders-is safe and effective for the management of hyperphosphatemia in patients receiving maintenance dialysis. METHODS This double-blind phase 3 trial enrolled 236 patients undergoing maintenance dialysis with hyperphosphatemia (defined in this trial as serum phosphorus 5.5-10 mg/dl inclusive) despite receiving phosphate binder therapy (sevelamer, nonsevelamer, sevelamer plus nonsevelamer, or multiple nonsevelamer binders). These participants were randomly assigned to receive oral tenapanor 30 mg twice daily or placebo for 4 weeks. The primary efficacy end point was the change in serum phosphorus concentration from baseline to week 4. RESULTS Of the 236 randomized patients, 235 (99.6%) were included in the full analysis set; this included 116 in the tenapanor plus binder group and 119 in the placebo plus binder group. A total of 228 patients (96.6%) completed the 4-week treatment period. In the full analysis set (mean age 54.5 years, 40.9% women), patients treated with tenapanor plus binder achieved a larger mean change in serum phosphorus concentration from baseline to week 4 compared with placebo plus binder (-0.84 versus -0.19 mg/dl, P<0.001). Diarrhea was the most commonly reported adverse event, resulting in study drug discontinuation in four of 119 (3.4%) and two of 116 (1.7%) patients receiving tenapanor plus binder or placebo plus binder, respectively. CONCLUSIONS A dual-mechanism treatment using both tenapanor and phosphate binders improved control of hyperphosphatemia in patients undergoing maintenance dialysis compared with phosphate binders alone. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER AMPLIFY, NCT03824587.
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Affiliation(s)
| | | | | | - Glenn M. Chertow
- Division of Nephrology, Stanford University School of Medicine, Stanford, California
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13
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Scialla JJ, Kendrick J, Uribarri J, Kovesdy CP, Gutiérrez OM, Jimenez EY, Kramer HJ. State-of-the-Art Management of Hyperphosphatemia in Patients With CKD: An NKF-KDOQI Controversies Perspective. Am J Kidney Dis 2021; 77:132-141. [PMID: 32771650 PMCID: PMC8109252 DOI: 10.1053/j.ajkd.2020.05.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 05/16/2020] [Indexed: 02/07/2023]
Abstract
Phosphate binders are among the most common medications prescribed to patients with kidney failure receiving dialysis and are often used in advanced chronic kidney disease (CKD). In patients with CKD glomerular filtration rate category 3a (G3a) or worse, including those with kidney failure who are receiving dialysis, clinical practice guidelines suggest "lowering elevated phosphate levels towards the normal range" with possible strategies including dietary phosphate restriction or use of binders. Additionally, guidelines suggest restricting the use of oral elemental calcium often contained in phosphate binders. Nutrition guidelines in CKD suggest<800-1,000mg of calcium daily, whereas CKD bone and mineral disorder guidelines do not provide clear targets, but<1,500mg in maintenance dialysis patients has been previously recommended. Many different classes of phosphate binders are now available and clinical trials have not definitively demonstrated the superiority of any class of phosphate binders over another with regard to clinical outcomes. Use of phosphate binders contributes substantially to patients' pill burden and out-of-pocket costs, and many have side effects. This has led to uncertainty regarding the use and best choice of phosphate binders for patients with CKD or kidney failure. In this controversies perspective, we discuss the evidence base around binder use in CKD and kidney failure with a focus on comparisons of available binders.
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Affiliation(s)
- Julia J Scialla
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA; Department of Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA.
| | - Jessica Kendrick
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jaime Uribarri
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Csaba P Kovesdy
- Department of Medicine, University of Tennessee Health Science Center and Memphis Veterans Affairs Medical Center, Memphis, TN
| | - Orlando M Gutiérrez
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL; Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL
| | - Elizabeth Yakes Jimenez
- Department of Pediatrics, University of New Mexico, Albuquerque, New Mexico; Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico; Nutrition Research Network, Academy of Nutrition and Dietetics, Chicago, IL
| | - Holly J Kramer
- Department of Medicine, Loyola University Chicago, Maywood, IL; Department of Public Health Sciences, Loyola University Chicago, Maywood, IL
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14
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Florenzano P, Jimenez M, Ferreira CR, Nesterova G, Roberts MS, Tella SH, Fernandez de Castro L, Gafni RI, Wolf M, Jüppner H, Gales B, Wesseling-Perry K, Markovich D, Gahl WA, Salusky IB, Collins MT. Nephropathic Cystinosis: A Distinct Form of CKD-Mineral and Bone Disorder that Provides Novel Insights into the Regulation of FGF23. J Am Soc Nephrol 2020; 31:2184-2192. [PMID: 32631973 DOI: 10.1681/asn.2019111172] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 05/18/2020] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The rare lysosomal storage disease nephropathic cystinosis presents with renal Fanconi syndrome that evolves in time to CKD. Although biochemical abnormalities in common causes of CKD-mineral and bone disorder have been defined, it is unknown if persistent phosphate wasting in nephropathic cystinosis is associated with a biochemical mineral pattern distinct from that typically observed in CKD-mineral and bone disorder. METHODS We assessed and compared determinants of mineral homeostasis in patients with nephropathic cystinosis across the predialysis CKD spectrum to these determinants in age- and CKD stage-matched patients, with causes of CKD other than nephropathic cystinosis. RESULTS The study included 50 patients with nephropathic cystinosis-related CDK and 97 with CKD from other causes. All major aspects of mineral homeostasis were differentially effected in patients with CKD stemming from nephropathic cystinosis versus other causes. Patients with nephropathic cystinosis had significantly lower percent tubular reabsorption of phosphate and fibroblast growth factor-23 (FGF23) at all CKD stages, and lower blood phosphate in CKD stages 3-5. Linear regression analyses demonstrated lower FGF23 levels in nephropathic cystinosis participants at all CKD stages when corrected for eGFR and age, but not when adjusted for serum phosphate. CONCLUSIONS Nephropathic cystinosis CKD patients have mineral abnormalities that are distinct from those in CKD stemming from other causes. Persistently increased urinary phosphate excretion maintains serum phosphate levels within the normal range, thus protecting patients with nephropathic cystinosis from elevations of FGF23 during early CKD stages. These findings support the notion that phosphate is a significant driver of increased FGF23 levels in CKD and that mineral abnormalities associated with CKD are likely to vary depending on the underlying renal disease.
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Affiliation(s)
- Pablo Florenzano
- Skeletal Disorders and Mineral Homeostasis Section, National Institutes of Dental and Craniofacial Research, Bethesda, Maryland .,Endocrinology Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Macarena Jimenez
- Endocrinology Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos R Ferreira
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Galina Nesterova
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Mary Scott Roberts
- Skeletal Disorders and Mineral Homeostasis Section, National Institutes of Dental and Craniofacial Research, Bethesda, Maryland
| | - Sri Harsha Tella
- Skeletal Disorders and Mineral Homeostasis Section, National Institutes of Dental and Craniofacial Research, Bethesda, Maryland
| | - Luis Fernandez de Castro
- Skeletal Disorders and Mineral Homeostasis Section, National Institutes of Dental and Craniofacial Research, Bethesda, Maryland
| | - Rachel I Gafni
- Skeletal Disorders and Mineral Homeostasis Section, National Institutes of Dental and Craniofacial Research, Bethesda, Maryland
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke University, Durham, North Carolina
| | - Harald Jüppner
- Endocrine Unit and Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Barbara Gales
- Division of Nephrology, Department of Pediatrics, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California
| | - Katherine Wesseling-Perry
- Division of Nephrology, Department of Pediatrics, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California
| | - Daniela Markovich
- Division of Nephrology, Department of Pediatrics, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California
| | - William A Gahl
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Isidro B Salusky
- Division of Nephrology, Department of Pediatrics, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California
| | - Michael T Collins
- Skeletal Disorders and Mineral Homeostasis Section, National Institutes of Dental and Craniofacial Research, Bethesda, Maryland
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15
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Vervloet MG. FGF23 measurement in chronic kidney disease: What is it really reflecting? Clin Chim Acta 2020; 505:160-166. [PMID: 32156608 DOI: 10.1016/j.cca.2020.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 12/20/2022]
Abstract
Fibroblast growth factor can be measured in clinical practice using ELISA, with acceptable validity. Different from many metabolites and minerals, its value can differ by a thousand-fold between individuals, largely because of differences in kidney function and dietary habits. This wide range complicates the proper interpretation of the concentration of FGF23, both in terms of the appropriateness of a given value for a given estimated GFR, and in terms of estimating the magnitude of risk for clinical events, with which FGF23 is clearly associated. In this narrative review, the impact of kidney function, exposure to phosphate from diet, and novel emerging factors that influence FGF23 concentrations are discussed. These and yet to define determinants of FGF23 question the causality of the association of FGF23 with hard (cardiovascular) endpoints, as observed in several epidemiological studies.
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Affiliation(s)
- Marc G Vervloet
- Amsterdam University Medical Center, Department of Nephrology, and Amsterdam Cardiovascular Sciences (ACS), Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands.
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16
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Abstract
PURPOSE OF REVIEW This review describes recent developments in the management of serum phosphate in dialysis patients, with a focus on the development of recent trials which randomize patients to different levels of control. RECENT FINDINGS We review the uncertainties around clinical benefits of serum phosphate control and alternative approaches to current management, as well as a multinational attempt to conduct randomized controlled trials in this area. We discuss novel methods of limiting oral phosphate absorption. SUMMARY Although numerous guidelines and target ranges for serum phosphate management exist, they are largely based on observational data and there is no definitive evidence that good control improves the length or quality of life of dialysis patients. New phosphate binders continue to appear on the market with increasing financial cost but without additional meaningful outcome data. Two recently published trials have demonstrated the feasibility of a large-scale study of differing phosphate levels to test the hypothesis that reduction of serum phosphate is beneficial to dialysis patients. Restriction of oral phosphate intake should not be overlooked.
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17
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Law JP, Price AM, Pickup L, Radhakrishnan A, Weston C, Jones AM, McGettrick HM, Chua W, Steeds RP, Fabritz L, Kirchhof P, Pavlovic D, Townend JN, Ferro CJ. Clinical Potential of Targeting Fibroblast Growth Factor-23 and αKlotho in the Treatment of Uremic Cardiomyopathy. J Am Heart Assoc 2020; 9:e016041. [PMID: 32212912 PMCID: PMC7428638 DOI: 10.1161/jaha.120.016041] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic kidney disease is highly prevalent, affecting 10% to 15% of the adult population worldwide and is associated with increased cardiovascular morbidity and mortality. As chronic kidney disease worsens, a unique cardiovascular phenotype develops characterized by heart muscle disease, increased arterial stiffness, atherosclerosis, and hypertension. Cardiovascular risk is multifaceted, but most cardiovascular deaths in patients with advanced chronic kidney disease are caused by heart failure and sudden cardiac death. While the exact drivers of these deaths are unknown, they are believed to be caused by uremic cardiomyopathy: a specific pattern of myocardial hypertrophy, fibrosis, with both diastolic and systolic dysfunction. Although the pathogenesis of uremic cardiomyopathy is likely to be multifactorial, accumulating evidence suggests increased production of fibroblast growth factor-23 and αKlotho deficiency as potential major drivers of cardiac remodeling in patients with uremic cardiomyopathy. In this article we review the increasing understanding of the physiology and clinical aspects of uremic cardiomyopathy and the rapidly increasing knowledge of the biology of both fibroblast growth factor-23 and αKlotho. Finally, we discuss how dissection of these pathological processes is aiding the development of therapeutic options, including small molecules and antibodies, directly aimed at improving the cardiovascular outcomes of patients with chronic kidney disease and end-stage renal disease.
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Affiliation(s)
- Jonathan P. Law
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of NephrologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Anna M. Price
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of NephrologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Luke Pickup
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Ashwin Radhakrishnan
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
| | - Chris Weston
- Institute of Immunology and ImmunotherapyUniversity of BirminghamUnited Kingdom
- NIHR Birmingham Biomedical Research CentreUniversity Hospitals Birmingham NHS Foundation Trust and University of BirminghamUnited Kingdom
| | - Alan M. Jones
- School of PharmacyUniversity of BirminghamUnited Kingdom
| | | | - Winnie Chua
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Richard P. Steeds
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of CardiologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Larissa Fabritz
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of CardiologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Paulus Kirchhof
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Davor Pavlovic
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Jonathan N. Townend
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of CardiologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Charles J. Ferro
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of NephrologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
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18
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Cozzolino M, Ketteler M, Wagner CA. An expert update on novel therapeutic targets for hyperphosphatemia in chronic kidney disease: preclinical and clinical innovations. Expert Opin Ther Targets 2020; 24:477-488. [PMID: 32191548 DOI: 10.1080/14728222.2020.1743680] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: The management of hyperphosphatemia in patients with chronic kidney disease (CKD) is complicated, requiring a multidisciplinary approach that includes dietary phosphate restriction, dialysis, and phosphate binders.Areas covered: We describe key players involved in regulating inorganic phosphate homeostasis and their differential role in healthy people and different stages of CKD. The contribution of paracellular and transcellular intestinal absorptive mechanisms are also examined. Finally, we illuminate recent therapeutic approaches for hyperphosphatemia in CKD. We searched PubMed/Medline (up to November 2019) using the following terms: chronic kidney disease, dialysis, diet, hyperphosphatemia, NaPi2b, nicotinamide, phosphate binder, secondary hyperparathyroidism, tenapanor and vascular calcification.Expert opinion: The precise mechanisms regulating intestinal phosphate absorption in humans is not completely understood. However, it is now established that this process involves two independent pathways: a) active transport (i.e. transcellular route, via specific ion transporters) and inactive transport (i.e. paracellular route across tight junctions). Dietary phosphate restriction and phosphate-binder use can lead to an undesirable maladaptive increase in phosphate uptake and promote active phosphate transport by increased expression of the gastrointestinal sodium-dependent phosphate transporter, NaPi2b. Nicotinamide may overcome these limitations through the inhibition of NaPi2b, by improved efficacy and reduced phosphate binder use and better compliance.
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Affiliation(s)
- Mario Cozzolino
- Renal Division, ASST Santi Paolo E Carlo, Department of Health Sciences, University of Milan, Milan, Italy
| | - Markus Ketteler
- Department of General Internal Medicine and Nephrology, Robert-Bosch-Krankenhaus, Stuttgart, Germany
| | - Carsten Alexander Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research, NCCR Kidney. CH, Zurich, Switzerland
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19
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Lacroix JS, Urena-Torres P. Potentielle application de l’axe fibroblast growth factor 23-Klotho dans la maladie rénale chronique. Nephrol Ther 2020; 16:83-92. [DOI: 10.1016/j.nephro.2019.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 05/19/2019] [Indexed: 12/17/2022]
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20
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Abstract
Chronic kidney disease (CKD) is a global health epidemic that accelerates cardiovascular disease, increases risk of infection, and causes anemia and bone disease, among other complications that collectively increase risk of premature death. Alterations in calcium and phosphate homeostasis have long been considered nontraditional risk factors for many of the most morbid outcomes of CKD. The discovery of fibroblast growth factor 23 (FGF23), which revolutionized the diagnosis and treatment of rare hereditary disorders of FGF23 excess that cause hypophosphatemic rickets, has also driven major paradigm shifts in our understanding of the pathophysiology and downstream end-organ complications of disordered mineral metabolism in CKD. As research of FGF23 in CKD has rapidly advanced, major new questions about its regulation and effects continuously emerge. These are promoting exciting innovations in laboratory, patient-oriented, and epidemiological research and stimulating clinical trials of new therapies and repurposing of existing ones to target FGF23.
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Affiliation(s)
- John Musgrove
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710, USA;
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710, USA; .,Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina 27710, USA
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21
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King AJ, Siegel M, He Y, Nie B, Wang J, Koo-McCoy S, Minassian NA, Jafri Q, Pan D, Kohler J, Kumaraswamy P, Kozuka K, Lewis JG, Dragoli D, Rosenbaum DP, O'Neill D, Plain A, Greasley PJ, Jönsson-Rylander AC, Karlsson D, Behrendt M, Strömstedt M, Ryden-Bergsten T, Knöpfel T, Pastor Arroyo EM, Hernando N, Marks J, Donowitz M, Wagner CA, Alexander RT, Caldwell JS. Inhibition of sodium/hydrogen exchanger 3 in the gastrointestinal tract by tenapanor reduces paracellular phosphate permeability. Sci Transl Med 2019; 10:10/456/eaam6474. [PMID: 30158152 DOI: 10.1126/scitranslmed.aam6474] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 10/31/2017] [Accepted: 03/06/2018] [Indexed: 12/16/2022]
Abstract
Hyperphosphatemia is common in patients with chronic kidney disease and is increasingly associated with poor clinical outcomes. Current management of hyperphosphatemia with dietary restriction and oral phosphate binders often proves inadequate. Tenapanor, a minimally absorbed, small-molecule inhibitor of the sodium/hydrogen exchanger isoform 3 (NHE3), acts locally in the gastrointestinal tract to inhibit sodium absorption. Because tenapanor also reduces intestinal phosphate absorption, it may have potential as a therapy for hyperphosphatemia. We investigated the mechanism by which tenapanor reduces gastrointestinal phosphate uptake, using in vivo studies in rodents and translational experiments on human small intestinal stem cell-derived enteroid monolayers to model ion transport physiology. We found that tenapanor produces its effect by modulating tight junctions, which increases transepithelial electrical resistance (TEER) and reduces permeability to phosphate, reducing paracellular phosphate absorption. NHE3-deficient monolayers mimicked the phosphate phenotype of tenapanor treatment, and tenapanor did not affect TEER or phosphate flux in the absence of NHE3. Tenapanor also prevents active transcellular phosphate absorption compensation by decreasing the expression of NaPi2b, the major active intestinal phosphate transporter. In healthy human volunteers, tenapanor (15 mg, given twice daily for 4 days) increased stool phosphorus and decreased urinary phosphorus excretion. We determined that tenapanor reduces intestinal phosphate absorption predominantly through reduction of passive paracellular phosphate flux, an effect mediated exclusively via on-target NHE3 inhibition.
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Affiliation(s)
| | | | - Ying He
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | - Ji Wang
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | | | | | - Deng Pan
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | | | | | | | | | | | - Debbie O'Neill
- University of Alberta, Edmonton, Alberta T6G 1C9, Canada
| | - Allein Plain
- University of Alberta, Edmonton, Alberta T6G 1C9, Canada
| | - Peter J Greasley
- Cardiovascular and Metabolic Disease (CVMD) Translational Medicine Unit, Early Clinical Development, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | | | - Daniel Karlsson
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | - Margareta Behrendt
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | - Maria Strömstedt
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | | | - Thomas Knöpfel
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Eva M Pastor Arroyo
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Nati Hernando
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Joanne Marks
- Department of Neuroscience, Physiology and Pharmacology, University College London, Royal Free Campus, London NW3 2PF, UK
| | - Mark Donowitz
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
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Rodelo-Haad C, Santamaria R, Muñoz-Castañeda JR, Pendón-Ruiz de Mier MV, Martin-Malo A, Rodriguez M. FGF23, Biomarker or Target? Toxins (Basel) 2019; 11:E175. [PMID: 30909513 PMCID: PMC6468608 DOI: 10.3390/toxins11030175] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 12/11/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) plays a key role in the complex network between the bones and other organs. Initially, it was thought that FGF23 exclusively regulated phosphate and vitamin D metabolism; however, recent research has demonstrated that an excess of FGF23 has other effects that may be detrimental in some cases. The understanding of the signaling pathways through which FGF23 acts in different organs is crucial to develop strategies aiming to prevent the negative effects associated with high FGF23 levels. FGF23 has been described to have effects on the heart, promoting left ventricular hypertrophy (LVH); the liver, leading to production of inflammatory cytokines; the bones, inhibiting mineralization; and the bone marrow, by reducing the production of erythropoietin (EPO). The identification of FGF23 receptors will play a remarkable role in future research since its selective blockade might reduce the adverse effects of FGF23. Patients with chronic kidney disease (CKD) have very high levels of FGF23 and may be the population suffering from the most adverse FGF23-related effects. The general population, as well as kidney transplant recipients, may also be affected by high FGF23. Whether the association between FGF23 and clinical events is causal or casual remains controversial. The hypothesis that FGF23 could be considered a therapeutic target is gaining relevance and may become a promising field of investigation in the future.
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Affiliation(s)
- Cristian Rodelo-Haad
- Nephrology Service, University Hospital Reina Sofia, 14005 Cordoba, Spain.
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/University of Cordoba, 14005 Cordoba, Spain.
- Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, 28040 Madrid, Spain.
| | - Rafael Santamaria
- Nephrology Service, University Hospital Reina Sofia, 14005 Cordoba, Spain.
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/University of Cordoba, 14005 Cordoba, Spain.
- Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, 28040 Madrid, Spain.
| | - Juan R Muñoz-Castañeda
- Nephrology Service, University Hospital Reina Sofia, 14005 Cordoba, Spain.
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/University of Cordoba, 14005 Cordoba, Spain.
- Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, 28040 Madrid, Spain.
| | - M Victoria Pendón-Ruiz de Mier
- Nephrology Service, University Hospital Reina Sofia, 14005 Cordoba, Spain.
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/University of Cordoba, 14005 Cordoba, Spain.
- Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, 28040 Madrid, Spain.
| | - Alejandro Martin-Malo
- Nephrology Service, University Hospital Reina Sofia, 14005 Cordoba, Spain.
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/University of Cordoba, 14005 Cordoba, Spain.
- Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, 28040 Madrid, Spain.
| | - Mariano Rodriguez
- Nephrology Service, University Hospital Reina Sofia, 14005 Cordoba, Spain.
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/University of Cordoba, 14005 Cordoba, Spain.
- Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, 28040 Madrid, Spain.
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Saurette M, Alexander RT. Intestinal phosphate absorption: The paracellular pathway predominates? Exp Biol Med (Maywood) 2019; 244:646-654. [PMID: 30764666 DOI: 10.1177/1535370219831220] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
IMPACT STATEMENT This review summarizes the work on transcellular intestinal phosphate absorption, arguing why this pathway is not the predominant pathway in humans consuming a "Western" diet. We then highlight the recent evidence which is strongly consistent with paracellular intestinal phosphate absorption mediating the bulk of intestinal phosphate absorption in humans.
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Affiliation(s)
- Matthew Saurette
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,2 The Women's & Children's Health Research Institute, Edmonton, Alberta T6G 1C9, Canada
| | - R Todd Alexander
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,2 The Women's & Children's Health Research Institute, Edmonton, Alberta T6G 1C9, Canada.,3 Department of Pediatrics, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
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Sorribas V, Guillén N, Sosa C. Substrates and inhibitors of phosphate transporters: from experimental tools to pathophysiological relevance. Pflugers Arch 2018; 471:53-65. [DOI: 10.1007/s00424-018-2241-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 11/21/2018] [Accepted: 11/25/2018] [Indexed: 12/26/2022]
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25
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Rodelo-Haad C, Rodríguez-Ortiz ME, Martin-Malo A, Pendon-Ruiz de Mier MV, Agüera ML, Muñoz-Castañeda JR, Soriano S, Caravaca F, Alvarez-Lara MA, Felsenfeld A, Aljama P, Rodriguez M. Phosphate control in reducing FGF23 levels in hemodialysis patients. PLoS One 2018; 13:e0201537. [PMID: 30086150 PMCID: PMC6080760 DOI: 10.1371/journal.pone.0201537] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 07/04/2018] [Indexed: 02/07/2023] Open
Abstract
Background In hemodialysis patients, high levels of Fibroblast Growth Factor 23 (FGF23) predict mortality. Our study was designed to test whether the control of serum phosphate is associated with a reduction in serum FGF23 levels. Additionally other variables with a potential effect on FGF23 levels were evaluated. Material and methods The effect of sustained (40-weeks) control of serum phosphate on FGF23 levels (intact and c-terminal) was evaluated in 21 stable hemodialysis patients that were not receiving calcimimetics or active vitamin D. Patients received non-calcium phosphate binders to maintain serum phosphate below 4.5 mg/dl. In an additional analysis, values of intact-FGF23 (iFGF23) and c-terminal FGF23 (cFGF23) from 150 hemodialysis patients were correlated with parameters of mineral metabolism and inflammation. Linear mixed models and linear regression were performed to evaluate longitudinal trajectories of variables and the association between FGF23 and the other variables examined. Results During the 40-week treatment, 12 of 21 patients achieved the target of serum phosphate <4.5 mg/dl. In these 12 patients, iFGF23 decreased to less than half whereas cFGF23 did not reduce significantly. In patients with serum phosphate >4.5 mg, iFGF23 and cFGF23 increased two and four-fold respectively as compared with baseline. Furthermore, changes in serum phosphate correlated with changes in C-reactive protein (hs-CRP). In our 150 hemodialysis patients, those in the higher tertile of serum phosphate also showed increased hs-CRP, iPTH, iFGF23 and cFGF23. Multiple regression analysis revealed that iFGF23 levels directly correlated with both serum phosphate and calcium, whereas cFGF23 correlated with serum phosphate and hs-CRP but not with calcium. Conclusions The control of serum phosphate reduced iFGF23. This reduction was also associated with a decreased in inflammatory parameters. Considering the entire cohort of hemodialysis patients, iFGF23 levels correlated directly with serum phosphate levels and also correlated inversely with serum calcium concentration. The levels of cFGF23 were closely related to serum phosphate and parameters of inflammation.
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Affiliation(s)
- Cristian Rodelo-Haad
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Maria E. Rodríguez-Ortiz
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Alejandro Martin-Malo
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
- * E-mail:
| | - M. Victoria Pendon-Ruiz de Mier
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - M. Luisa Agüera
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Juan R. Muñoz-Castañeda
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Sagrario Soriano
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | | | - M. Antonia Alvarez-Lara
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Arnold Felsenfeld
- Wadsworth VA, UCLA, Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and the David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California
| | - Pedro Aljama
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
| | - Mariano Rodriguez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
- Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain
- RETICs-REDinREN (National Institute of Health Carlos III), Madrid, Spain
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Fouque D, Vervloet M, Ketteler M. Targeting Gastrointestinal Transport Proteins to Control Hyperphosphatemia in Chronic Kidney Disease. Drugs 2018; 78:1171-1186. [PMID: 30022383 PMCID: PMC6132443 DOI: 10.1007/s40265-018-0950-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Management of hyperphosphatemia in patients with dialysis-dependent chronic kidney disease remains a major challenge, requiring a multifaceted approach that includes dietary phosphate restriction, dialysis, and phosphate binders. However, these treatments fail to meet serum phosphate targets in many patients, potentially further exacerbating the significant morbidity and mortality burden associated with the disease. Recent advances in our understanding of the mechanisms underlying phosphate homeostasis have shed new light on the issue and suggest that gastrointestinal transport proteins may be promising targets for new hyperphosphatemia treatments. Drugs that inhibit or downregulate these transport proteins, and thus reduce phosphate uptake from the gut, may overcome some of the limitations of existing phosphate-lowering strategies, such as interdialytic rises in serum phosphate levels, poor adherence to dietary and phosphate-binder regimens, and maladaptive responses that can increase gastrointestinal phosphate absorption. Here, we review the latest preclinical and clinical data for two candidates in this novel drug class: tenapanor, a small-molecule inhibitor of the sodium/hydrogen ion-exchanger isoform 3, and nicotinamide, an inhibitor of sodium-phosphate-2b cotransporters. We also discuss how potential synergies in their mechanisms of action suggest that coadministering phosphate binders with sodium-phosphate-2b cotransporter inhibitors may yield additive benefits over traditional phosphate-binder therapy.
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Affiliation(s)
- Denis Fouque
- Department of Nephrology, Centre Hospitalier Lyon-Sud, Université de Lyon, Carmen, 165 Chemin du Grand Revoyet, 69495, Pierre-Bénite, France
| | - Marc Vervloet
- Department of Nephrology and Amsterdam Cardiovascular Sciences (ACS), VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, Netherlands
| | - Markus Ketteler
- Division of Nephrology, Klinikum Coburg GmbH, Ketschendorfer Str. 33, D-96450, Coburg, Germany.
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