Sodium Zirconium Cyclosilicate in Chronic Kidney Disease, Hyperkalemia, and Metabolic Acidosis: NEUTRALIZE Randomized Study.

BACKGROUND: Metabolic acidosis and hyperkalemia are common in chronic kidney disease (CKD). A potential dual effect of sodium zirconium cyclosilicate (SZC), a selective binder of potassium in the gastrointestinal tract, on serum potassium (sK+) and serum bicarbonate (sHCO3-) was evaluated in patients with hyperkalemia and metabolic acidosis associated with CKD. METHODS: In the NEUTRALIZE study (NCT04727528), non-dialysis patients with stage 3-5 CKD, hyperkalemia (sK+ >5.0 to ≤5.9 mmol/l) and metabolic acidosis (sHCO3- 16-20 mmol/l) received open-label SZC 10 g three times daily for ≤48 hours. Patients achieving normokalemia (sK+ 3.5-5.0 mmol/l) were randomized 1:1 to SZC 10 g or placebo daily for 4 weeks. Primary endpoint was patients (%) maintaining normokalemia at end of treatment (EOT) without rescue. Secondary endpoints included mean change in sHCO3- at EOT (Day 29), and patients (%) normokalemic with a ≥3-mmol/l increase in sHCO3- without rescue. RESULTS: Of 229 patients screened, 37 were randomized (SZC, n = 17; placebo, n = 20). High screen failure led to early study termination. At EOT, 88.2% (SZC) versus 20.0% (placebo) of patients maintained normokalemia (odds ratio 56.2; P = 0.001). Low enrollment rendered secondary endpoint P-values nominal. SZC treatment provided nominally significant increases in sHCO3- versus placebo from Day 15 onwards. Patients who were normokalemic with a ≥3-mmol/l increase in sHCO3- without rescue were 35.3% (SZC) and 5.0% (placebo; P < 0.05). No new safety concerns were reported. CONCLUSIONS: SZC effectively lowered sK+ and maintained normokalemia, with nominally significant increases in sHCO3- observed for SZC versus placebo.

A Phase 2 Trial of Sibeprenlimab in Patients with IgA Nephropathy.

BACKGROUND: A proliferation-inducing ligand (APRIL) is implicated in the pathogenesis of IgA nephropathy. Sibeprenlimab is a humanized IgG2 monoclonal antibody that binds to and neutralizes APRIL. METHODS: In this phase 2, multicenter, double-blind, randomized, placebo-controlled, parallel-group trial, we randomly assigned adults with biopsy-confirmed IgA nephropathy who were at high risk for disease progression, despite having received standard-care treatment, in a 1:1:1:1 ratio to receive intravenous sibeprenlimab at a dose of 2, 4, or 8 mg per kilogram of body weight or placebo once monthly for 12 months. The primary end point was the change from baseline in the log-transformed 24-hour urinary protein-to-creatinine ratio at month 12. Secondary end points included the change from baseline in the estimated glomerular filtration rate (eGFR) at month 12. Safety was also assessed. RESULTS: Among 155 patients who underwent randomization, 38 received sibeprenlimab at a dose of 2 mg per kilogram, 41 received sibeprenlimab at a dose of 4 mg per kilogram, 38 received sibeprenlimab at a dose of 8 mg per kilogram, and 38 received placebo. At 12 months, the geometric mean ratio reduction (±SE) from baseline in the 24-hour urinary protein-to-creatinine ratio was 47.2±8.2%, 58.8±6.1%, 62.0±5.7%, and 20.0±12.6% in the sibeprenlimab 2-mg, 4-mg, and 8-mg groups and the placebo group, respectively. At 12 months, the least-squares mean (±SE) change from baseline in eGFR was -2.7±1.8, 0.2±1.7, -1.5±1.8, and -7.4±1.8 ml per minute per 1.73 m2 in the sibeprenlimab 2-mg, 4-mg, and 8-mg groups and the placebo group, respectively. The incidence of adverse events that occurred after the start of administration of sibeprenlimab or placebo was 78.6% in the pooled sibeprenlimab groups and 71.1% in the placebo group. CONCLUSIONS: In patients with IgA nephropathy, 12 months of treatment with sibeprenlimab resulted in a significantly greater decrease in proteinuria than placebo. (Funded by Visterra; ENVISION ClinicalTrials.gov number, NCT04287985; EudraCT number, 2019-002531-29.).

A PRoliferation-Inducing Ligand (APRIL) in the Pathogenesis of Immunoglobulin A Nephropathy: A Review of the Evidence.

A PRoliferation-Inducing Ligand (APRIL), the thirteenth member of the tumor necrosis factor superfamily, plays a key role in the regulation of activated B cells, the survival of long-lived plasma cells, and immunoglobulin (Ig) isotype class switching. Several lines of evidence have implicated APRIL in the pathogenesis of IgA nephropathy (IgAN). Globally, IgAN is the most common primary glomerulonephritis, and it can progress to end-stage kidney disease; yet, disease-modifying treatments for this condition have historically been lacking. The preliminary data in ongoing clinical trials indicate that APRIL inhibition can reduce proteinuria and slow the rate of kidney disease progression by acting at an upstream level in IgAN pathogenesis. In this review, we examine what is known about the physiologic roles of APRIL and evaluate the experimental and epidemiological evidence describing how these normal biologic processes are thought to be subverted in IgAN. The weight of the preclinical, clinical, and genetic data supporting a key role for APRIL in IgAN has galvanized pharmacologic research, and several anti-APRIL drug candidates have now entered clinical development for IgAN. Herein, we present an overview of the clinical results to date. Finally, we explore where more research and evidence are needed to transform potential therapies into clinical benefits for patients with IgAN.

Sparsentan versus Irbesartan in Focal Segmental Glomerulosclerosis.

BACKGROUND: An unmet need exists for focal segmental glomerulosclerosis (FSGS) treatment. In an 8-week, phase 2 trial, sparsentan, a dual endothelin-angiotensin receptor antagonist, reduced proteinuria in patients with FSGS. The efficacy and safety of longer-term treatment with sparsentan for FSGS are unknown. METHODS: In this phase 3 trial, we enrolled patients with FSGS (without known secondary causes) who were 8 to 75 years of age; patients were randomly assigned to receive sparsentan or irbesartan (active control) for 108 weeks. The surrogate efficacy end point assessed at the prespecified interim analysis at 36 weeks was the FSGS partial remission of proteinuria end point (defined as a urinary protein-to-creatinine ratio of ≤1.5 [with protein and creatinine both measured in grams] and a >40% reduction in the ratio from baseline). The primary efficacy end point was the estimated glomerular filtration rate (eGFR) slope at the time of the final analysis. The change in eGFR from baseline to 4 weeks after the end of treatment (week 112) was a secondary end point. Safety was also evaluated. RESULTS: A total of 371 patients underwent randomization: 184 were assigned to receive sparsentan and 187 to receive irbesartan. At 36 weeks, the percentage of patients with partial remission of proteinuria was 42.0% in the sparsentan group and 26.0% in the irbesartan group (P = 0.009), a response that was sustained through 108 weeks. At the time of the final analysis at week 108, there were no significant between-group differences in the eGFR slope; the between-group difference in total slope (day 1 to week 108) was 0.3 ml per minute per 1.73 m2 of body-surface area per year (95% confidence interval [CI], -1.7 to 2.4), and the between-group difference in the slope from week 6 to week 108 (i.e., chronic slope) was 0.9 ml per minute per 1.73 m2 per year (95% CI, -1.3 to 3.0). The mean change in eGFR from baseline to week 112 was -10.4 ml per minute per 1.73 m2 with sparsentan and -12.1 ml per minute per 1.73 m2 with irbesartan (difference, 1.8 ml per minute per 1.73 m2; 95% CI, -1.4 to 4.9). Sparsentan and irbesartan had similar safety profiles, and the frequency of adverse events was similar in the two groups. CONCLUSIONS: Among patients with FSGS, there were no significant between-group differences in eGFR slope at 108 weeks, despite a greater reduction in proteinuria with sparsentan than with irbesartan. (Funded by Travere Therapeutics; DUPLEX ClinicalTrials.gov number, NCT03493685.).

Efficacy and safety of sparsentan versus irbesartan in patients with IgA nephropathy (PROTECT): 2-year results from a randomised, active-controlled, phase 3 trial.

BACKGROUND: Sparsentan, a novel, non-immunosuppressive, single-molecule, dual endothelin angiotensin receptor antagonist, significantly reduced proteinuria versus irbesartan, an angiotensin II receptor blocker, at 36 weeks (primary endpoint) in patients with immunoglobulin A nephropathy in the phase 3 PROTECT trial's previously reported interim analysis. Here, we report kidney function and outcomes over 110 weeks from the double-blind final analysis. METHODS: PROTECT, a double-blind, randomised, active-controlled, phase 3 study, was done across 134 clinical practice sites in 18 countries throughout the Americas, Asia, and Europe. Patients aged 18 years or older with biopsy-proven primary IgA nephropathy and proteinuria of at least 1·0 g per day despite maximised renin-angiotensin system inhibition for at least 12 weeks were randomly assigned (1:1) to receive sparsentan (target dose 400 mg oral sparsentan once daily) or irbesartan (target dose 300 mg oral irbesartan once daily) based on a permuted-block randomisation method. The primary endpoint was proteinuria change between treatment groups at 36 weeks. Secondary endpoints included rate of change (slope) of the estimated glomerular filtration rate (eGFR), changes in proteinuria, a composite of kidney failure (confirmed 40% eGFR reduction, end-stage kidney disease, or all-cause mortality), and safety and tolerability up to 110 weeks from randomisation. Secondary efficacy outcomes were assessed in the full analysis set and safety was assessed in the safety set, both of which were defined as all patients who were randomly assigned and received at least one dose of randomly assigned study drug. This trial is registered with ClinicalTrials.gov, NCT03762850. FINDINGS: Between Dec 20, 2018, and May 26, 2021, 203 patients were randomly assigned to the sparsentan group and 203 to the irbesartan group. One patient from each group did not receive the study drug and was excluded from the efficacy and safety analyses (282 [70%] of 404 included patients were male and 272 [67%] were White) . Patients in the sparsentan group had a slower rate of eGFR decline than those in the irbesartan group. eGFR chronic 2-year slope (weeks 6-110) was -2·7 mL/min per 1·73 m2 per year versus -3·8 mL/min per 1·73 m2 per year (difference 1·1 mL/min per 1·73 m2 per year, 95% CI 0·1 to 2·1; p=0·037); total 2-year slope (day 1-week 110) was -2·9 mL/min per 1·73 m2 per year versus -3·9 mL/min per 1·73 m2 per year (difference 1·0 mL/min per 1·73 m2 per year, 95% CI -0·03 to 1·94; p=0·058). The significant reduction in proteinuria at 36 weeks with sparsentan was maintained throughout the study period; at 110 weeks, proteinuria, as determined by the change from baseline in urine protein-to-creatinine ratio, was 40% lower in the sparsentan group than in the irbesartan group (-42·8%, 95% CI -49·8 to -35·0, with sparsentan versus -4·4%, -15·8 to 8·7, with irbesartan; geometric least-squares mean ratio 0·60, 95% CI 0·50 to 0·72). The composite kidney failure endpoint was reached by 18 (9%) of 202 patients in the sparsentan group versus 26 (13%) of 202 patients in the irbesartan group (relative risk 0·7, 95% CI 0·4 to 1·2). Treatment-emergent adverse events were well balanced between sparsentan and irbesartan, with no new safety signals. INTERPRETATION: Over 110 weeks, treatment with sparsentan versus maximally titrated irbesartan in patients with IgA nephropathy resulted in significant reductions in proteinuria and preservation of kidney function. FUNDING: Travere Therapeutics.

Vadadustat for treatment of anemia in patients with dialysis-dependent chronic kidney disease receiving peritoneal dialysis.

BACKGROUND: Hypoxia-inducible factor prolyl hydroxylase inhibitors such as vadadustat may provide an oral alternative to injectable erythropoiesis-stimulating agents for treating anemia in patients receiving peritoneal dialysis. In two randomized (1:1), global, phase 3, open-label, sponsor-blind, parallel-group, active-controlled noninferiority trials in patients with dialysis-dependent chronic kidney disease (INNO2VATE), vadadustat was noninferior to darbepoetin alfa with respect to cardiovascular safety and hematological efficacy. Vadadustat's effects in patients receiving only peritoneal dialysis is unclear. METHODS: We conducted a post hoc analysis of patients in the INNO2VATE trials receiving peritoneal dialysis at baseline. The prespecified primary safety endpoint was time to first major cardiovascular event (MACE; defined as all-cause mortality or nonfatal myocardial infarction or stroke). The primary efficacy endpoint was mean change in hemoglobin from baseline to the primary evaluation period (Weeks 24-36). RESULTS: Of the 3923 patients randomized in the two INNO2VATE trials, 309 were receiving peritoneal dialysis (vadadustat, n = 152; darbepoetin alfa, n = 157) at baseline. Time to first MACE was similar in the vadadustat and darbepoetin alfa groups [hazard ratio 1.10; 95% confidence interval (CI) 0.62, 1.93]. In patients receiving peritoneal dialysis, the difference in mean change in hemoglobin concentrations was -0.10 g/dL (95% CI -0.33, 0.12) in the primary evaluation period. The incidence of treatment-emergent adverse events (TEAEs) was 88.2% versus 95.5%, and serious TEAEs was 52.6% versus 73.2% in the vadadustat and darbepoetin alfa groups, respectively. CONCLUSIONS: In the subgroup of patients receiving peritoneal dialysis in the phase 3 INNO2VATE trials, safety and efficacy of vadadustat were similar to darbepoetin alfa.

Effects of phosphate binders in moderate CKD.

Some propose using phosphate binders in the CKD population given the association between higher levels of phosphorus and mortality, but their safety and efficacy in this population are not well understood. Here, we aimed to determine the effects of phosphate binders on parameters of mineral metabolism and vascular calcification among patients with moderate to advanced CKD. We randomly assigned 148 patients with estimated GFR=20-45 ml/min per 1.73 m(2) to calcium acetate, lanthanum carbonate, sevelamer carbonate, or placebo. The primary endpoint was change in mean serum phosphorus from baseline to the average of months 3, 6, and 9. Serum phosphorus decreased from a baseline mean of 4.2 mg/dl in both active and placebo arms to 3.9 mg/dl with active therapy and 4.1 mg/dl with placebo (P=0.03). Phosphate binders, but not placebo, decreased mean 24-hour urine phosphorus by 22%. Median serum intact parathyroid hormone remained stable with active therapy and increased with placebo (P=0.002). Active therapy did not significantly affect plasma C-terminal fibroblast growth factor 23 levels. Active therapy did, however, significantly increase calcification of the coronary arteries and abdominal aorta (coronary: median increases of 18.1% versus 0.6%, P=0.05; abdominal aorta: median increases of 15.4% versus 3.4%, P=0.03). In conclusion, phosphate binders significantly lower serum and urinary phosphorus and attenuate progression of secondary hyperparathyroidism among patients with CKD who have normal or near-normal levels of serum phosphorus; however, they also promote the progression of vascular calcification. The safety and efficacy of phosphate binders in CKD remain uncertain.

How long is the warranty period for nil or low coronary artery calcium in patients new to hemodialysis?

BACKGROUND: Coronary artery calcification (CAC) is common in patients with advanced chronic kidney disease on dialysis. A sizeable proportion of patients has no or minimal CAC at the inception of dialysis, but it is unclear how long they remain free of it. METHODS: For the purpose of this study, 36 incident hemodialysis patients were submitted to sequential chest computed tomography to quantify CAC at baseline, 6, 12, 18 and 30 months. RESULTS: Among them, 15 had absent or minimal CAC score (CACS 0 to 30) and 21 had a CACS>30 at baseline. Overall, the median baseline CACS was 129 (interquartile range [IQR]=0-709) and it increased to 364 (IQR=8.3-1683) at study completion (182% increase). Among the 15 patients with minimal CACS, only 3 progressed and the median CACS increase was 20, as opposed to 15 of 21 patients with a baseline CACS>30 whose median progression was 431 (p<0.02). The 18 patients who had CACS progression were older (68.5 vs. 57.3 years, p=0.0081) and exhibited a poorer control of mineral metabolism (phosphorus 5.2 vs. 4.9 mg/ dL, p=0.048; corrected calcium x phosphorus product [CaxP] 49.3 vs. 46.2 mg2/dL2, p=0.001) than the patients without progression. On multivariable analysis, independent predictors of progression were baseline CACS (p=0.038) and time-averaged Cax;P (p=0.077). CONCLUSION: These data suggest that absent or low CAC at baseline is associated with minimal progression even up to 30 months. Careful management of mineral metabolism appears to be one of the main factors that limit progression of CAC.

The effect of combined calcium and vitamin D3 supplementation on serum intact parathyroid hormone in moderate CKD.

BACKGROUND: Studies addressing the effects of vitamin D(3) supplementation on secondary hyperparathyroidism in patients with moderate chronic kidney disease are scarce. STUDY DESIGN: Post hoc analysis of the randomized clinical trial Vitamin D, Calcium, Lyon Study II (DECALYOS II) to assess effects according to baseline estimated glomerular filtration rate (eGFR). SETTING & PARTICIPANTS: Multicenter, randomized, double-blinded, placebo-controlled study of 639 elderly women randomly assigned to calcium-vitamin D(3) fixed combination; calcium plus vitamin D(3) separate combination, or placebo. INTERVENTIONS: Placebo or calcium (1,200 mg) and vitamin D(3) (800 IU) in fixed or separate combination. OUTCOMES & MEASUREMENTS: Proportion of participants with a mean decrease in intact parathyroid hormone (iPTH) level of 30% or greater. eGFR was calculated using the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation and categorized as 60 or greater, 45 to 59, and less than 45 mL/min/1.73 m(2). RESULTS: 610 participants had an eGFR at baseline: 288 (47.2%), 222 (36.4%), and 100 (16.4%) were in each decreasing eGFR category. Across decreasing eGFR groups, 88%, 86%, and 89% had 25-hydroxyvitamin D (25[OH]D) levels less than 15 ng/mL at baseline. On treatment, similar improvements in the proportion of participants achieving 25(OH)D levels greater than 30 ng/mL at 6 months were seen in all kidney function groups (43%, 49%, and 41%, respectively). Active regimens versus placebo increased mean 25(OH)D levels from baseline in all eGFR groups at all times (P < 0.001 for all). The proportion with a 30% or greater decrease in iPTH level at 6 months was 50% in all eGFR groups on treatment versus 6% to 9% for placebo (P < 0.001 for all). The effects of the intervention on iPTH levels did not differ according to baseline eGFR (interaction P > 0.1 for all times). LIMITATIONS: This study included only elderly white women. CONCLUSION: Vitamin D(3) was effective in increasing 25(OH)D and decreasing iPTH levels in patients with moderate chronic kidney disease.

Phosphorus balance with daily dialysis.

Hyperphosphatemia is an almost universal finding in patients with end-stage renal disease and is associated with increased all-cause mortality, cardiovascular mortality, and vascular calcification. These associations have raised the question of whether reducing phosphorus levels could result in improved survival. In light of the recent findings that increased per-session dialysis dose, as assessed by urea kinetics, did not result in improved survival, the definition of adequacy of dialysis should be re-evaluated and consideration given to alternative markers. Two alternatives to conventional thrice weekly dialysis (CHD) are nocturnal hemodialysis (NHD) and short daily hemodialysis (SDHD). The elimination kinetics of phosphorus as they relate to these alternative daily dialysis schedules and the clinical implications of overall phosphorus balance are discussed here. The total weekly phosphorus removal with NHD is more than twice that removed by CHD (4985 mg/week +/- 1827 mg vs. 2347 mg/week +/- 697 mg) and this is associated with a significantly lower average serum phosphorous (4.0 mg/dl vs. 6.5 mg/dl). In spite of the observed increase in protein and phosphorus intake seen in patients on SDHD, phosphate binder requirements and serum phosphorus levels are generally stable to decrease although this effect is strongly dependent on the frequency and overall treatment time.

Phosphate binders: new products and challenges.

Optimal phosphate control in dialysis patients is extremely challenging. A growing awareness of the deleterious effect of mineral metabolism imbalances together with the lack of a satisfactory explanation for the exaggerated mortality rate in patients undergoing renal replacement therapy has led to a renewed effort to refine our approach to hyperphosphatemia. However, despite the remarkable improvements in dialysis techniques, phosphate control has not substantially improved. Achieving normo-phosphatemia presents a multitude of practical and scientific challenges related to the optimal target level, cardiovascular health, and drug toxicities. It is the aim of the present review to summarize briefly the controversies associated with currently available phosphate binders, a cornerstone in the current management of hyperphosphatemia.