Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial

Research trends and performance of endothelin A receptor antagonist in kidney care: a bibliometric analysis

BACKGROUND

Endothelin A receptor antagonists (ERAs) have emerged as pivotal therapeutic agents in managing pulmonary hypertension (PH) and various kidney disorders, including chronic kidney disease (CKD) and proteinuric glomerular diseases such as IgA nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS). Although initially developed for pulmonary applications, recent research has highlighted their renoprotective effects, expanding their role in nephrology. This study presents a comprehensive bibliometric analysis of global research trends, key contributors, and emerging applications of ERAs in kidney care over the past three decades.

METHODS

A bibliometric analysis was performed using the Science Citation Index Expanded database (1992-2023). Relevant kidney-related publications were identified through specific keyword searches. Author performance was assessed using the Y-index.

RESULTS

ERA-related research has shown significant growth, particularly in nephrology. The United States and the University of Groningen lead in publication volume and international collaborations, with H.J.L. Heerspink emerging as a key contributor. While PH remains the dominant research focus, nephrology applications are rapidly increasing, particularly in CKD, diabetic nephropathy (DN), and glomerular diseases. A major milestone was the accelerated FDA approval of sparsentan for IgAN in 2023, followed by full approval in 2024 based on confirmatory efficacy data. However, challenges such as fluid retention and cardiovascular risks remain, necessitating further investigation into optimized ERA therapies, including combination strategies with SGLT2 inhibitors.

CONCLUSIONS

The expanding role of ERAs in nephrology underscores their potential in treating proteinuric kidney diseases. Ongoing international collaborations are advancing research on ERA safety, efficacy, and novel therapeutic strategies, supporting their broader clinical application.

The role of endothelin receptor antagonists in kidney disease

Kidney diseases are among the most prevalent conditions worldwide, impacting over 850 million individuals. They are categorized into acute kidney injury and chronic kidney disease. Current preclinical and clinical trials have demonstrated that endothelin (ET) is linked to the onset and progression of kidney disease. In kidney diseases, pathological conditions such as hyperglycemia, acidosis, insulin resistance, and elevated angiotensin II levels lead to an increase in ET. This elevation activates endothelin receptor type A, resulting in harmful effects like proteinuria and a reduced glomerular filtration rate (GFR). Therefore, to slow the progression of kidney disease, endothelin receptor antagonists (ERAs) have been proposed as promising new therapies. Numerous studies have demonstrated the efficacy of ERAs in significantly reducing proteinuria and improving GFR, thereby slowing the progression of kidney diseases. This review discusses the mechanisms of action of ERAs in treating kidney disease, their efficacy and safety in preclinical and clinical studies, and explores future prospects for ERAs.

Real-world assessment of sparsentan's drug safety framework

BACKGROUND

Sparsentan has been approved for reducing proteinuria in adult patients with primary IgA nephropathy (IgAN) at risk of rapid disease progression, yet comprehensive studies evaluating its drug safety framework are lacking.

METHODS

Adverse event (AE) reports following the market release of sparsentan were collected from the U.S. Food and Drug Administration AE Reporting System. Disproportionate analysis was used to identify previously unrecognized positive novel signals at both the system organ class and preferred term levels. Additionally, analysis on clinical priorities and subgroup analysis were conducted.

RESULTS

A total of 504 patients with IgAN were included. Two novel system organ classes and 14 novel preferred terms were identified. Hypotension and dizziness were established as moderate clinical priority events. Males had a higher relative risk of nausea, peripheral edema, feeling abnormal, decreased blood pressure, and hypotension, while females were at greater risk for fatigue, pain, increased blood creatinine, dizziness, and somnolence. Among those aged 18-45, the relative risk of experiencing fatigue, pain, and dizziness was higher, individuals aged 45 and older had a higher relative risk of peripheral edema, decreased blood pressure, and hypotension.

CONCLUSIONS

Based on the available AE reporting data, sparsentan exhibits a favorable safety profile, with no high-priority clinical events identified. Our findings offer valuable insights to optimize the use of sparsentan and understand its potential side effects.

Contribution of the glomerular filtration rate slope to the kidney hierarchical composite endpoint

INTRODUCTION

A recent chronic kidney disease (CKD) progression hierarchical composite endpoint (HCE) utilizes the glomerular filtration rate (GFR) slope for participants without a dichotomous event. Here, we evaluated clinical interpretations when HCE analyses are driven by GFR slope comparisons.

METHODS

Using CKD trial data, we calculated win odds using only GFR slope; dichotomous kidney events and GFR slope; all-cause mortality, dichotomous kidney events, and GFR slope; and all-cause mortality with dichotomous kidney events.

RESULTS

Win odds (95% confidence interval) calculated from pairwise GFR slope only comparisons were 1.44 (1.34-1.55), 1.60 (1.49-1.72), 1.19 (1.10-1.28), and 0.82 (0.78-0.86) in the DAPA-CKD, CREDENCE, SONAR, and ALTITUDE trials, respectively. Win odds were similar for the GFR slope only and full kidney HCE with and without mortality.

CONCLUSIONS

These results support incorporation of GFR slope into the CKD progression HCE and help to interpret the magnitude of treatment effect on kidney HCE estimated with win odds.

Endothelin-1 signaling in the kidney: recent advances and remaining gaps

The involvement of endothelin-1 (ET-1) in the maintenance of kidney function as well as its role in renal pathophysiology has been appreciated for decades; however, there still exist important gaps in knowledge in our understanding of the mechanistic pathways activated by this system in the kidney. The purpose of this article is to review recent advances in the field, as well as to underscore areas that need more investigation, with an emphasis on the interplay of ET-1 with inflammation, sex differences, circadian rhythms of renal function, the most recent clinical trials involving the ET-1 system, and the interaction between microRNAs and the ET-1 system.

Obesity-related glomerulopathy: How it happens and future perspectives

Obesity-related glomerulopathy (ORG) is an emerging complication of excess adiposity. Its incidence rises alongside the obesity pandemic. Up to 40% of individuals can be affected by ORG, irrespective of the status of glomerular filtration rate and albuminuria. ORG is a distinct histological diagnosis based on kidney biopsy, showing classical features of an enlarged glomerulus with and without focal segmental glomerulosclerosis in the perihilar region seen with all categories of obesity. About 10% of individuals with ORG may progress to end-stage kidney disease. The invasive nature of kidney biopsy highlights the need for non-invasive biomarkers for improved screening, diagnosis and risk prediction of ORG. These biomarkers may narrow the gaps in the management of ORG by improving: (1) screening, diagnosis and differentiation of ORG from non-ORG conditions; (2) risk prediction and stratification of individuals at risk of progression to end-stage kidney disease including the detection of trajectories of progression; (3) monitoring of treatment safety and effectiveness and (4) development of novel therapeutic targets. In the present review, we discussed the pathophysiology, emerging biomarkers (such as kidney injury molecule-1 [KIM-1], uromodulin, klotho, circulating microRNA-21 [miR-21]) and future treatment strategies (metabolic surgery, sodium-glucose cotransporter-2 inhibitors, incretin-based therapy and non-steroidal mineralocorticoid antagonists) of ORG.

G-Protein-Coupled Receptors in Chronic Kidney Disease Induced by Hypertension and Diabetes

Hypertension and diabetes are two common causes of chronic kidney disease. Hypertension can induce renal vascular injury, glomerular damage, podocyte loss, and tubular injury, leading to tubulointerstitial fibrosis. A number of factors influence the regulation of hypertension, among which G-protein-coupled receptors (GPCRs) have been studied extensively because they are desirable targets for drug development. Compared to hypertension, the regulatory effects of GPCRs on hypertensive kidney disease (HKD) are less generalized. In this review, we discussed the GPCRs involved in hypertensive kidney disease, such as angiotensin II receptors (AT1R and AT2R), Mas receptor (MasR), Mas-related G-protein-coupled receptor member D (MrgD), relaxin family receptor 1 (RXFP1), adenosine receptors (A1, A2A, A2B, and A3), purinergic P2Y receptors, and endothelin receptors (ETA and ETB). The progression of HKD is rarely reversed but can be retarded by ameliorating the hypertensive microenvironment in the kidneys. However, simply reducing blood pressure cannot stop the progression of HKD. Diabetic nephropathy (DN) is the most common cause of end-stage renal disease (ESRD), which is a major cause of morbidity and mortality in diabetes. Many GPCRs are involved in DN. Here, we select some well-studied GPCRs that are directly associated with the pathogenesis of DN to illustrate their mechanisms. The main purpose of this review is to provide an overview of the GPCRs involved in the occurrence and progression of HKD and DN and their probable pathophysiological mechanisms, which we hope will help in developing new therapeutic strategies.

Risk-directed management of chronic kidney disease

The timely and rational institution of therapy is a key step towards reducing the global burden of chronic kidney disease (CKD). CKD is a heterogeneous entity with varied aetiologies and diverse trajectories, which include risk of kidney failure but also cardiovascular events and death. Developments in the past decade include substantial progress in CKD risk prediction, driven in part by the accumulation of electronic health records data. In addition, large randomized clinical trials have demonstrated the effectiveness of sodium-glucose co-transporter 2 inhibitors, glucagon-like peptide 1 receptor agonists and mineralocorticoid receptor antagonists in reducing adverse events in CKD, greatly expanding the options for effective therapy. Alongside angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, these classes of medication have been proposed to be the four pillars of CKD pharmacotherapy. However, all of these drug classes are underutilized, even in individuals at high risk. Leveraging prognostic estimates to guide therapy could help clinicians to prescribe CKD-related therapies to those who are most likely to benefit from their use. Risk-based CKD management thus aligns patient risk and care, allowing the prioritization of absolute benefit in determining therapeutic selection and timing. Here, we discuss CKD prognosis tools, evidence-based management and prognosis-guided therapies.

Advances and challenges in kidney fibrosis therapeutics

Chronic kidney disease (CKD) is a major global health burden that affects more than 10% of the adult population. Current treatments, including dialysis and transplantation, are costly and not curative. Kidney fibrosis, defined as an abnormal accumulation of extracellular matrix in the kidney parenchyma, is a common outcome in CKD, regardless of disease aetiology, and is a major cause of loss of kidney function and kidney failure. For this reason, research efforts have focused on identifying mediators of kidney fibrosis to inform the development of effective anti-fibrotic treatments. Given the prominent role of the transforming growth factor-β (TGFβ) family in fibrosis, efforts have focused on inhibiting TGFβ signalling. Despite hopes raised by the efficacy of this approach in preclinical models, translation into clinical practice has not met expectations. Antihypertensive and antidiabetic drugs slow the decline in kidney function and could slow fibrosis but, owing to the lack of technologies for in vivo renal imaging, their anti-fibrotic effect cannot be truly assessed at present. The emergence of new drugs targeting pro-fibrotic signalling, or enabling cell repair and cell metabolic reprogramming, combined with better stratification of people with CKD and the arrival of nanotechnologies for kidney-specific drug delivery, open up new perspectives for the treatment of this major public health challenge.

Innovative therapeutics for renoprotection: Where we are

Chronic kidney disease (CKD) has become highly prevalent worldwide, with major implications for public health, including increased risk of progression to kidney failure, cardiovascular events, and mortality. Up to a decade ago, renin-angiotensin system inhibitors, that is angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers, were the only available pharmacological interventions to slow kidney function loss and limit the associated cardiovascular morbidity and mortality in this context. More recently, landmark trials have demonstrated the ability of novel therapeutics to significantly ameliorate kidney and cardiovascular outcomes in patients with CKD, when added on top of optimized renin-angiotensin system blockade. These include sodium-glucose cotransporter-2 inhibitors in patients with diabetic and nondiabetic kidney disease, as well as the nonsteroidal mineralcorticoid receptor antagonist finerenone and the glucagon-like peptide-1 receptor agonist semaglutide in patients with diabetic kidney disease. We herein review the evolving scenario and the latest evidence for the treatment of CKD, mainly focusing on proteinuric CKD. We started with a presentation of established and more recently approved classes of kidney protective drugs, followed by a discussion of therapeutic interventions under clinical investigation to slow CKD progression. Finally, we underscore the added value of personalized and multidrug interventions, which are becoming increasingly more feasible with the availability of a growing number of kidney protective agents, and are likely to stand as the most powerful tools to safely slow, or even prevent, the progression of proteinuric CKD. SIGNIFICANCE STATEMENT: Chronic kidney disease (CKD) is highly prevalent globally, and is associated with substantial morbidity and mortality. This review provides a comprehensive overview of the currently approved and emerging therapeutic options for the treatment of proteinuric CKD. As novel kidney protective agents have recently become available, the outcomes of patients with CKD could hopefully improve over the few decades ahead.

Efficacy and safety of endothelin receptor antagonists in non-diabetic kidney nephropathy : A systematic review and meta-analysis

BACKGROUND

Recent evidence increasingly confirms the therapeutic potential of endothelin receptor antagonists (ERA) in treating non-diabetic kidney nephropathy. However, clinical data in this area remain limited. Therefore, we conducted this meta-analysis to investigate the efficacy and safety of ERAs in the treatment of non-diabetic kidney nephropathy.

METHODS

Randomized controlled trials were identified through PubMed, WOS, Embase, Cochrane Library and Google scholar. The initial participant characteristics and primary outcome measures were gathered, followed by the calculation of risk ratios (RR) and 95% confidence intervals (CI). Additionally, subgroup analyses were conducted to investigate the sources of heterogeneity.

RESULT

In this study, seven randomized, controlled trials (RCT) were included. The results indicated that patients in the ERAs group exhibited a greater mean reduction in the urinary protein to creatinine ratio (UPCR) (standardized mean difference, MD -28.08, 95% CI -33.59 to -22.57, p < 0.001). The number of patients experiencing either complete or partial remission from proteinuria notably increased when treated with ERAs (complete remission: odds ratio, OR = 3.14, 95% CI 2.23-4.42, p < 0.001; partial remission: OR = 3.03, 95% CI 2.33-3.96, p < 0.001). Furthermore, ERAs delayed the decline in the estimated glomerular filtration rate (eGFR, MD = 3.81, 95% CI 1.71-5.90, p < 0.001). However, the incidence of edema events slightly increased in the ERA group (OR = 1.42, 95% CI 1.04-1.93, p = 0.03).

CONCLUSION

The use of ERAs is more effective than regimens without ERAs in slowing the progression of non-diabetic nephropathy.

Endothelin receptor antagonists for diabetic kidney disease: back to the future?

INTRODUCTION

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease worldwide. Endothelin-1 (ET-1) is a potent vasoconstrictor secreted by vascular endothelial cells, actively involved in the pathophysiology of numerous cardiovascular diseases. Based on the differential downstream effects of ET-1 binding to its two distinct types of receptors (ETA/ETB) within the kidney, selective ETA receptor blockade has been long proposed as a promising treatment modality for DKD.

AREAS COVERED

This review aims to examine the available evidence base for the use of ERAs in the treatment of DKD, by critically reappraising available landmark trials and discussing their possible position in the context of current treatment of this disease.

EXPERT OPINION

Despite early enthusiasm and widespread expectations, endothelin receptor antagonists (ERAs) faded into obscurity following the release of the first randomized controlled trials (RCTs). More recent RCTs using different compounds have re-introduced ERAs as a promising treatment in the growing pharmaceutical armamentarium of DKD. While the future of DKD management will be based on a more personalized approach, new, robust evidence from appropriately designed RCTs is eagerly anticipated to clearly define the role of ERAs in DKD.

Aprocitentan for Blood Pressure Reduction in Black Patients

BACKGROUND

Black individuals frequently present with resistant hypertension and disproportionately increased cardiovascular risk. We investigated the blood pressure (BP)-lowering effect of the dual endothelin receptor antagonist aprocitentan in Black individuals enrolled in the PRECISION study (Parallel-Group, Phase 3 Study with Aprocitentan in Subjects with Resistant Hypertension).

METHODS

Patients with confirmed resistant hypertension were randomized to aprocitentan 12.5 mg, 25 mg, or placebo for 4 weeks (part 1). They subsequently received aprocitentan 25 mg for 32 weeks (part 2) before re-randomization to aprocitentan 25 mg or placebo (part 3).

RESULTS

Eighty-two patients randomized in the PRECISION study were Black individuals. At week 4, aprocitentan 12.5 and 25 mg reduced office trough systolic BP (-11.3 and -11.9 mm Hg) to a similar degree as placebo (-12.0 mm Hg). Using 24-hour ambulatory BP monitoring, the placebo effect was minimal (-0.7 mm Hg), and aprocitentan reduced systolic BP by 4.0 and 8.6 mm Hg. During part 2, office BP continued to decrease (-16.4 mm Hg at week 36). In part 3, office and ambulatory systolic BP increased on placebo (+9.9 and +8.1 mm Hg, respectively), whereas the BP-lowering effect was maintained with aprocitentan. Aprocitentan markedly reduced albuminuria during the study. The most frequent adverse event was peripheral edema, occurring in 3 patients (10%) receiving aprocitentan 25 mg versus none receiving aprocitentan 12.5 mg or placebo.

CONCLUSIONS

Aprocitentan reduced BP and albuminuria in Black individuals with resistant hypertension. The BP-lowering efficacy was similar to that of the overall PRECISION population. Aprocitentan may represent an important addition to the often difficult-to-control hypertension in Black individuals.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03541174.

Bridging the Gap Between CKD Management Paradigms in Transplant and Nontransplant Settings: Published Evidence, Challenges, and Perspectives

Kidney transplantation (KT) is the best treatment for patients with kidney failure, associated with improved survival and quality of life compared with maintenance dialysis. However, despite constant improvements in the assessment and management of the alloimmune response, KT patients frequently demonstrate a reduced estimated glomerular filtration rate. Therefore, the usual complications of chronic kidney disease (CKD), such as anemia, hypertension, metabolic acidosis, hyperkalemia, or persistent secondary hyperparathyroidism, are highly prevalent after KT. However, their underlying mechanisms are different in the transplant setting (compared with the nontransplanted CKD population), and management recommendations are based on relatively poor-quality data. In recent years, new therapies have emerged, significantly improving kidney and cardiovascular outcomes of non-KT patients with CKD. Whether those new drugs could improve the outcomes of KT patients has largely been under investigated so far. In this review, we will address the challenges of the management of a KT patient with a reduced estimated glomerular filtration rate, cover the published evidence, and highlight the critical knowledge gaps.

Fibrosis: cross-organ biology and pathways to development of innovative drugs

Fibrosis is a pathophysiological mechanism involved in chronic and progressive diseases that results in excessive tissue scarring. Diseases associated with fibrosis include metabolic dysfunction-associated steatohepatitis (MASH), inflammatory bowel diseases (IBDs), chronic kidney disease (CKD), idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc), which are collectively responsible for substantial morbidity and mortality. Although a few drugs with direct antifibrotic activity are approved for pulmonary fibrosis and considerable progress has been made in the understanding of mechanisms of fibrosis, translation of this knowledge into effective therapies continues to be limited and challenging. With the aim of assisting developers of novel antifibrotic drugs, this Review integrates viewpoints of biologists and physician-scientists on core pathways involved in fibrosis across organs, as well as on specific characteristics and approaches to assess therapeutic interventions for fibrotic diseases of the lung, gut, kidney, skin and liver. This discussion is used as a basis to propose strategies to improve the translation of potential antifibrotic therapies.

mTOR pathway: A key player in diabetic nephropathy progression and therapeutic targets

Diabetic nephropathy is a prevalent complication of diabetes and stands as the primary contributor to end-stage renal disease. The global prevalence of diabetic nephropathy is on the rise, however, due to its intricate pathogenesis, there is currently an absence of efficacious treatments to enhance renal prognosis in affected patients. The mammalian target of rapamycin (mTOR), a serine/threonine protease, assumes a pivotal role in cellular division, survival, apoptosis delay, and angiogenesis. It is implicated in diverse signaling pathways and has been observed to partake in the progression of diabetic nephropathy by inhibiting autophagy, promoting inflammation, and increasing oxidative stress. In this academic review, we have consolidated the understanding of the pathological mechanisms associated with four distinct resident renal cell types (podocytes, glomerular mesangial cells, renal tubular epithelial cells, and glomerular endothelial cells), as well as macrophages and T lymphocytes, within a diabetic environment. Additionally, we highlight the research progress in the treatment of diabetic nephropathy with drugs and various molecules interfering with the mTOR signaling pathway, providing a theoretical reference for the treatment and prevention of diabetic nephropathy.

Endothelin receptor antagonists in chronic kidney disease

Endothelin-1 is a potent vasoconstrictor that has diverse physiological functions in the kidney, including in the regulation of blood flow and glomerular filtration, electrolyte homeostasis and endothelial function. Overexpression of endothelin-1 contributes to the pathophysiology of both diabetic and non-diabetic chronic kidney disease (CKD). Selective endothelin receptor antagonists (ERAs) that target the endothelin A (ETA) receptor have demonstrated benefits in animal models of kidney disease and in clinical trials. In patients with type 2 diabetes and CKD, the selective ETA ERA, atrasentan, reduced albuminuria and kidney function decline. Concerns about the increased risks of fluid retention and heart failure with ERA use have led to the design of further trials to optimize dosing and patient selection. More recent studies have shown that the dual ETA receptor and angiotensin receptor blocker, sparsentan, preserved kidney function with minimal fluid retention in patients with IgA nephropathy. Moreover, combined administration of a low dose of the ETA-selective ERA, zibotentan, with the sodium-glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin, enhanced albuminuria reduction and mitigated fluid retention in patients with CKD. Notably, sparsentan and aprocitentan have received FDA approval for the treatment of IgA nephropathy and treatment-resistant hypertension, respectively. This Review describes our current understanding of the use of ERAs in patients with CKD to guide their optimal safe and effective use in clinical practice.

Sex differences in response to the endothelin receptor antagonist atrasentan in individuals with type 2 diabetes and chronic kidney disease: a post hoc analysis of the SONAR trial

AIMS/HYPOTHESIS

In the Study Of diabetic Nephropathy with AtRasentan (SONAR), the endothelin receptor antagonist (ERA) atrasentan slowed progression of chronic kidney disease (CKD) in individuals with type 2 diabetes. Pre-clinical research suggests sex-based differences in the endothelin system might influence the efficacy and safety of atrasentan. We therefore assessed the effects of atrasentan in men and women participating in SONAR.

METHODS

SONAR was a double-blind, placebo-controlled trial that compared atrasentan 0.75 mg/day with placebo in individuals with type 2 diabetes and CKD (eGFR 25-75 ml/min per 1.73 m2, urine albumin/creatinine ratio [UACR] 300-5000 mg/g). The primary endpoint was defined as the time from randomisation to the first occurrence of a doubling in serum creatinine or kidney failure (eGFR <15 ml/min per 1.73 m2, chronic dialysis, kidney transplantation or death from kidney failure). Hospitalisation for heart failure was the secondary endpoint. We performed Cox proportional hazards regression analyses to compare the treatment effect of atrasentan between male and female participants on the risk of the composite kidney outcome as well as hospitalisation for heart failure. Additionally, differences between male and female participants in atrasentan plasma exposure and eGFR change were assessed using, respectively, a t test and linear mixed effect model.

RESULTS

Among 3668 randomised participants, 946 (25.8%) were female. Atrasentan significantly reduced the risk of the composite kidney outcome in female participants (HR 0.46 [95% CI 0.28, 0.76]) but not in male participants (HR 0.83 [95% CI 0.65, 1.05]; p value for interaction 0.032). Atrasentan compared with placebo reduced eGFR decline to a greater extent in female than in male participants (treatment effect difference between male vs female participants -0.99 ml/min per 1.73 m2, p value for interaction=0.020). The RR for hospitalisation for heart failure with atrasentan vs placebo was 1.14 (95% CI 0.74, 1.76) in male participants and 1.88 (95% CI 0.98, 3.63) in female participants (p value for interaction=0.217). Female participants also had significantly higher atrasentan plasma exposure than male participants (geometric mean AUC 54.5 vs 42.6 ng/ml×h; p<0.001).

CONCLUSIONS/INTERPRETATION

Atrasentan showed greater kidney protection in female than in male participants but also induced more heart failure events in the female participants. These data suggest that sex-specific dosing regimens may be considered to optimise ERA treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01858532.

Novel pharmacological approaches to lowering blood pressure and managing hypertension

Hypertension is the leading cause of death globally, primarily due to its strong association with cardiovascular disease. The global prevalence of hypertension has surged over the past three decades, driven by rising rates of diabetes mellitus and obesity. Despite current antihypertensive therapies, only a small proportion of patients with hypertension achieve adequate blood pressure control, necessitating novel therapeutic strategies. In this Review we explore the challenges and emerging opportunities in hypertension management. Aprocitentan, a dual endothelin receptor antagonist, is the first agent from a novel class of antihypertensive drug to be licensed since 2007 and exemplifies innovative treatments on the horizon. Here we also address the complex factors contributing to poor hypertension control, including genetic influences, lifestyle factors, therapeutic inertia and poor patient adherence. We discuss the limitations of existing therapies and highlight promising new pharmacological approaches to hypertension management. Integrating these novel treatments alongside current pharmaceuticals combined with improved diagnostic and management strategies could substantially reduce the global burden of hypertension and associated cardiovascular disease.

Atrasentan in Patients with IgA Nephropathy

BACKGROUND

Patients with IgA nephropathy and severe proteinuria have a high lifetime risk of kidney failure. The efficacy and safety of the selective endothelin type A receptor antagonist atrasentan in reducing proteinuria in patients with IgA nephropathy are incompletely understood.

METHODS

We are conducting a phase 3, multinational, double-blind, randomized, controlled trial involving adults with biopsy-proven IgA nephropathy, a total urinary protein excretion of at least 1 g per day, and an estimated glomerular filtration rate of at least 30 ml per minute per 1.73 m2 of body-surface area. Patients were randomly assigned to receive atrasentan (0.75 mg per day) or matched placebo for 132 weeks. The primary outcome, assessed at a prespecified interim analysis of data from the first 270 patients in the main stratum, was the change in the 24-hour urinary protein-to-creatinine ratio from baseline to week 36; the change was estimated with the use of a repeated-measures model. (An exploratory stratum of patients who were receiving a sodium-glucose cotransporter 2 inhibitor were included in a separate analysis.) Safety analyses were based on adverse events across the entire main stratum.

RESULTS

A total of 340 patients were recruited into the main stratum. Among the first 270 patients in the main stratum (135 per trial group) who completed the week 36 visit, the geometric mean percentage change in the urinary protein-to-creatinine ratio relative to baseline was significantly greater with atrasentan (-38.1%) than with placebo (-3.1%), with a geometric mean between-group difference of -36.1 percentage points (95% confidence interval, -44.6 to -26.4; P<0.001). The percentage of patients with adverse events did not differ substantially between the two groups. Fluid retention was reported by 19 of 169 patients (11.2%) in the atrasentan group and in 14 of 170 (8.2%) in the placebo group but did not lead to discontinuation of the trial regimen. No apparent cases of cardiac failure or severe edema occurred.

CONCLUSIONS

In this prespecified interim analysis, atrasentan resulted in a significant and clinically meaningful reduction in proteinuria as compared with placebo in patients with IgA nephropathy. (Funded by Novartis; ALIGN ClinicalTrials.gov number, NCT04573478.).

Combination therapy as a new standard of care in diabetic and non-diabetic chronic kidney disease

Combination therapy, involving the use of multiple medications together, is becoming a new standard of care for chronic kidney disease (CKD). For people with CKD, combination therapy offers the promise of preventing kidney failure and reducing the risk of heart problems. This approach is appealing because different drugs target distinct mechanisms involved in CKD progression. For instance, some target immune responses, others reduce kidney inflammation and scarring, while others improve blood pressure within the kidneys. Data from large clinical trials suggest that each treatment works effectively on its own, regardless of other medications people are taking. Combining therapies can also reduce the risk of side effects of individual medications. This review highlights the evidence for combination therapy in CKD, explores how to improve its use, and discusses how future studies may answer remaining questions.

ABSTRACT

A range of therapies now exists to reduce the risk of kidney failure and cardiovascular events in people with type 2 diabetes, including renin-angiotensin system blockade, sodium-glucose cotransporter 2 (SGLT2) inhibitors, non-steroidal mineralocorticoid receptor antagonists, and glucagon-like peptide-1 receptor agonists. With multiple clinical trials underway, it is likely that at least some of these therapies-as well as additional agents such as endothelin receptor antagonists-will further demonstrate kidney-protective effects in people with CKD who do not have diabetes in the near future. For conditions such as IgA nephropathy, several therapies have recently been approved or are being evaluated in late phase trials. Thus combination therapy is emerging as a new standard for diabetic and non-diabetic chronic kidney disease (CKD). This approach is supported by randomized data suggesting that each therapeutic class offers independent and additive benefits in diabetic kidney disease, regardless of background therapy. Notably, the reduction in hyperkalaemia and fluid retention with SGLT2 inhibitors may enhance the tolerability and safety of other treatments. In this review, we present the rationale for combination therapy with evidence-based kidney therapies in diabetic and non-diabetic CKD. We also summarize randomized evidence supporting a multi-medicine approach, address safety considerations, review ongoing trials, and propose frameworks for implementing treatments aligned with patient risk to optimize person-centred care and reduce long-term risks of kidney failure and related complications.

Selective endothelin A receptor antagonism in chronic kidney disease: improving clinical application

Endothelin-1 (ET-1) is a peptide that is involved in various chronic diseases including cardiovascular and kidney disease. ET-1 can bind to two receptors, endothelin A (ETA) and endothelin B (ETB), which are found in different organs and tissues. When ET-1 binds to the ETA receptor, it causes blood vessels to narrow, while binding of ET-1 to the ETB receptor causes blood vessels to widen. These receptors help regulate fluid and electrolyte balance in the kidneys, as well as the kidney's ability to filter various substances out of the body. Overactivation of ET-1 can occur in people with diabetes or obesity, which can damage the structure and function of the kidney.Studies in mice and humans with kidney disease have shown that blocking the ETA receptor improves kidney health. As a result, medicines that specifically block the ETA receptor, known as endothelin receptor antagonists (ERAs), are a promising option for treating these kidney diseases. The first ERA (sparsentan) is now available for use in patients with immunoglobulin A (IgA) nephropathy, a specific type of kidney disease. It should be noted that ERAs can cause side effects. Fluid retention, which can increase the risk of heart failure, is a side effect that is particularly observed in patients with type 2 diabetes and severe kidney disease. This side effect is less often observed in patients with IgA nephropathy or patients without diabetes.Treatment strategies to optimize safe and effective use of ETA blockers are being developed. Overall, these insights offer hope for better care of patients with kidney disease.

ABSTRACT

Endothelin-1 (ET-1) is a 21-amino acid peptide involved in numerous cardiovascular and renal processes. ET-1 can bind to endothelin receptor A (ETA) and endothelin receptor B (ETB), which are found in various organs and tissues. In general, binding of ET-1 to the ETA receptor causes vasoconstriction, whereas activation of the ETB receptor leads to vasodilation. In the kidney, endothelin receptors regulate fluid and electrolyte balance, regional blood flow and glomerular filtration rate. In pathological conditions, ET-1 promotes kidney injury through adverse effects on the endothelial glycocalyx, podocytes and mesangial cells, and stimulating inflammation and fibrosis in the tubules. In experimental and clinical studies, inhibition of the ETA receptor has been shown beneficial in a variety of kidney diseases. These include diabetic kidney disease, immunoglobulin A nephropathy, focal segmental glomerulosclerosis and Alport syndrome. Accordingly, selective ETA endothelin receptor antagonists (ERA) may prove a viable therapeutic option in these diseases. However, clinical application is challenged by the occurrence of fluid retention which can lead to heart failure, in particular in patients with severe CKD. Concomitant use of sodium-glucose cotransporter 2 inhibitors (SGLT2i) may mitigate these adverse effects through their diuretic actions. The development of highly selective ETA antagonists, such as atrasentan and zibotentan, and the opportunities of combining these with SGLT2i, holds promise to optimize efficacy and safety of ERAs in clinical practice.

Design considerations for future renoprotection trials in the era of multiple therapies for chronic kidney disease

In the last 5-10 years, several large high-quality research trials testing new treatments versus a dummy treatment in patients with kidney disease have provided new discoveries, particularly among people with diabetes. Some of these trials included patients with a wide variety of kidney diseases and therefore provided important information on how effective the treatment is, and whether it is safe to use for many people (and not just those with a specific type of kidney disease). The findings are particularly important as they suggest that, once established, kidney disease progresses in similar ways regardless of the initiating cause. These new treatments importantly slow kidney disease progression but, even when used together, do not arrest the loss of kidney function. New research is still needed to test new potential treatments. Now that we have several drugs that can be used to treat kidney disease, there are new challenges when designing and conducting new trials. These include the reduced risk of kidney disease progression and heart disease (because of the new treatments available). Future research trials need to include a sufficiently large number of patients to be able to answer research questions reliably. In addition, different types of people and diseases should be included. In an age of increasing regulation and bureaucracy, conducting such trials is challenging. Simplifying the design and conduct of future trials by focusing only on the necessary components needed to answer the research key question(s) is important. Such trials reduce the burden of participation for patients and busy clinical staff, whilst still ensuring careful focus on patient safety and data quality. We hope more high-quality trials that are sufficiently large, inclusive and simple will be conducted in the future, so that kidney teams can offer better care to their patients.

ABSTRACT

Nephrology has benefited from conducting increasingly large high-quality trials in the last 5-10 years. In addition to the long-standing known benefits of renin-angiotensin system inhibitors, we now have multiple pharmacotherapies that provide kidney and/or cardiovascular protection for certain types of patient with chronic kidney disease (CKD). These include sodium-glucose co-transporter 2 inhibitors (SGLT2i), a non-steroidal mineralocorticoid receptor antagonist and a glucagon-like peptide-1 receptor agonist. Trials of SGLT2i have had particularly important impact, as wide eligibility criteria in pivotal trials have enabled safety and efficacy across a wide range of causes of CKD to be demonstrated. These findings support the concept of final common pathways of CKD progression and should encourage similar trial designs recruiting broad ranges of patients at risk of CKD progression. This is important as these new drugs do not completely arrest CKD progression nor do they mitigate the full excess of cardiovascular disease. In the current era of multiple therapies to manage risk of CKD progression, trial design and conduct also need to consider new challenges. These include falling event rates, establishing standard of care for participants pre-randomization and improving the inclusion of trial participants understudied in previous trials. Streamlining trial design and conduct and reducing participation burden for patients and clinicians is increasingly important to facilitate larger sample sizes and to optimize adherence to study interventions and follow-up. Potential other solutions include maintaining a focus on wide generalizability (to include understudied patient groups) and empowering patients to volunteer for trials (through public and patient involvement and large-scale invitation methods), as well as innovations in trial design (including use of pre-randomization run-in periods to implement standard of care and factorial or platform trials to assess multiple treatments simultaneously).

The road ahead: emerging therapies for primary IgA nephropathy

Primary IgA nephropathy (IgAN) is the most common form of primary glomerulopathy. A slowly progressive disease presenting in the young to middle-aged, most patients with reduced eGFR or proteinuria will progress to end-stage kidney disease (ESKD) in their lifetimes. The pathogenesis involves increased production of galactose-deficient IgA1 (Gd-IgA1) that forms immune complexes that deposit in the glomerulus, eliciting mesangial cell proliferation, inflammation, and complement activation. The backbone of therapy is supportive, including lifestyle modifications, strict blood pressure control, and renin-angiotensin system inhibition targeting proteinuria < 300 mg/day. Sodium-glucose transporter 2 inhibitors are indicated for persisting proteinuria or declining eGFR. Sparsentan is indicated for persisting proteinuria. Immunosuppression should be considered for all patients at risk for progression (persisting proteinuria and/or declining eGFR). To reduce Gd-IgA1 production, targeted-release budesonide is approved. Agents targeting B cell survival factors APRIL or BAFF/APRIL have significantly reduced Gd-IgA1 production and proteinuria in phase 2 trials but await phase 3 data for approval. To reduce inflammation, high-dose steroids are ineffective and toxic in Caucasian patients, although lower-dose regimens may be effective in Chinese patients. Complement inhibition is being actively studied. The factor B inhibitor iptacopan has conditional approval. The terminal pathway inhibitors cemdisiran and ravulizumab show promise in phase 2 studies. Our current approach for those requiring immunosuppression involves combining the reduction of Gd-IgA1 (nefecon) with suppressing the effects of inflammation (iptacopan). The optimal duration of such therapy is uncertain. Clearly, there is more to be learned with many trials underway.

The effect of the endothelin receptor antagonist atrasentan on insulin resistance in phenotypic clusters of patients with type 2 diabetes and chronic kidney disease

AIMS

Type 2 diabetes (T2D) patients with a clinical phenotype characterized by a high degree of insulin resistance are at increased risk of chronic kidney disease (CKD). We previously demonstrated that the endothelin receptor antagonist (ERA) atrasentan reduced insulin resistance in T2D. In this study, we compared the effect of atrasentan on insulin resistance across different phenotypic clusters of patients with T2D.

MATERIALS AND METHODS

We performed a post hoc analysis of the SONAR trial, a randomized, placebo-controlled trial of the ERA atrasentan in patients with T2D and CKD. Patients were stratified into four previously identified phenotypic clusters: severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD) and mild age-related diabetes (MARD). Changes in insulin resistance, assessed by HOMA-IR, were compared between the phenotypic clusters using a mixed effects model.

RESULTS

In total, 931 patients were included in the analysis. In the overall population, atrasentan compared to placebo reduced HOMA-IR by 12.9% [95%CI 3.5,21.4]. This effect of atrasentan was more pronounced in clusters characterized by insulin resistance or deficiency: (SIRD cluster 26.2% [95% CI 3.8,43.3] and SIDD cluster 18.5% [95%CI -3.8,35.9]), although the latter did not reach statistical significance. The effect of atrasentan compared to placebo was less pronounced in the other two clusters (MARD 12.2% [95% CI -1.7,24.12] and MOD -5.3% [95% CI -28.9,13.9]).

CONCLUSIONS

Atrasentan significantly improved insulin sensitivity in patients with T2D and CKD, especially in those characterized by high insulin resistance (SIRD cluster). Further studies are warranted to investigate the long-term clinical outcomes of atrasentan treatment in these distinct phenotypic clusters.

Traditional, alternative, and emerging therapeutics for focal segmental glomerulosclerosis

INTRODUCTION

Segmental focal glomerulosclerosis is a histological lesion characterized by podocyte damage. It may be a primary disease linked to an unknown circulating factor, secondary to viral infections, drug toxicity, or a disadaptive response to the loss of nephrons, or it may depend on gene mutations or have an indeterminate cause. The treatment of the primary form involves immunosuppressors. Additional pharmacotherapies for residual proteinuria are used, and emerging therapies are being studied to target other pathological pathways.

AREAS COVERED

This paper covers the treatment of FSGS, focusing on traditional and emerging therapeutic strategies. It is based on the KDIGO 2021 guidelines and supplemented by a literature search conducted on PubMed.

EXPERT OPINION

Treating FSGS is challenging due to its heterogeneity. Immunosuppression is adequate for primary FSGS but harmful in genetic or secondary forms. Key strategies include targeting the underlying cause and using agents that affect renal hemodynamics. Antifibrotic drugs can help slow kidney damage by addressing chronic inflammation and fibrosis. Alongside pharmacological treatments, managing blood pressure and restricting dietary salt are crucial. Finally, personalized treatment requires stratifying patients based on clinical, genetic, and histological data to improve clinical trial design and outcomes.

Chronic kidney disease

Chronic kidney disease (CKD) is defined by persistent abnormalities of kidney function or structure that have consequences for the health. A progressive decline of excretory kidney function has effects on body homeostasis. CKD is tightly associated with accelerated cardiovascular disease and severe infections, and with premature death. Kidney failure without access to kidney replacement therapy is fatal - a reality in many regions of the world. CKD can be the consequence of a single cause, but CKD in adults frequently relates rather to sequential injuries accumulating over the life course or to the presence of concomitant risk factors. The shared pathomechanism of CKD progression is the irreversible loss of kidney cells or nephrons together with haemodynamic and metabolic overload of the remaining nephrons, leading to further loss of kidney cells or nephrons. The management of patients with CKD focuses on early detection and on controlling all modifiable risk factors. This approach includes reducing the overload of the remaining nephrons with inhibitors of the renin-angiotensin system and the sodium-glucose transporter 2, as well as disease-specific drug interventions, if available. Hypertension, anaemia, metabolic acidosis and secondary hyperparathyroidism contribute to cardiovascular morbidity and reduced quality of life, and require diagnosis and treatment.

Study Design and Baseline Characteristics of ALIGN, a Randomized Controlled Study of Atrasentan in Patients With IgA Nephropathy

Introduction

Endothelin A (ETA) receptor activation is a driver of proteinuria, kidney inflammation, and fibrosis in IgA nephropathy (IgAN). Atrasentan, a selective ETA receptor antagonist, has potential to reduce proteinuria and preserve kidney function in IgAN. ALIGN (NCT04573478) is a phase 3, randomized, double-blind, placebo-controlled clinical trial of atrasentan in patients with IgAN at high risk of kidney function loss.

Methods

Eligibility criteria for the ALIGN main stratum included patients with biopsy-proven IgAN, total protein excretion ≥ 1 g/d, estimated glomerular filtration rate (eGFR) ≥ 30 ml/min per 1.73 m2, receiving a maximally tolerated stable dose of a renin-angiotensin system (RAS) inhibitor. An exploratory stratum enrolled participants also receiving a stable dose of sodium glucose cotransporter-2 inhibitors (SGLT2i). Participants were randomized to 0.75 mg atrasentan or placebo orally daily for 132 weeks followed by a 4-week wash-out period. The primary outcome is proteinuria change from baseline (24-hour urine protein-to-creatinine ratio [UPCR]) to week 36 in the main stratum. Key secondary end points include eGFR change from baseline to week 136, safety, and tolerability.

Results

Enrolment occurred across 20 countries; 404 patients were randomized: 340 in the main stratum and 64 in the SGLT2i stratum. At baseline in the main stratum, mean age was 44.7 years, 42.4% were female, mean eGFR and median UPCR were 58.9 ml/min per 1.73 m2 and 1.4 g/g, respectively.

Conclusion

The ongoing ALIGN trial evaluates the efficacy and safety of atrasentan in a representative global IgAN population at risk for disease progression despite optimized RAS inhibitor therapy and includes an exploratory stratum evaluating atrasentan use in combination with an SGLT2i.

First real-world evidence of sparsentan efficacy in patients with IgA nephropathy treated with SGLT2 inhibitors

Background

Sparsentan, a dual-acting antagonist for both the angiotensin II receptor type 1 and the endothelin receptor type A, has emerged as a promising therapeutic agent for the treatment of IgA nephropathy (IgAN). Following the publication of the PROTECT trial, sparsentan recently received approval for the treatment of IgAN in Europe. However, it remains uncertain whether an additive effect can be observed in the context of existing treatment with sodium-glucose co-transporter 2 (SGLT2) inhibitors, given that the PROTECT study did not investigate this dual therapy approach.

Methods

A total of 23 patients with IgAN were treated with sparsentan via the Managed Access Programme between December 2023 and August 2024. The patients were stable on maximum tolerated doses of renin-angiotensin system (RAS) and SGLT2 inhibitors, with an estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m² and a urine protein/creatinine ratio (UPCR) >0.75 g/g.

Results

In the 23 patients, median (IQR) baseline eGFR (CKD-EPI) was 42 mL/min/1.73 m2 (32-63) and median baseline UPCR was 1.5 g/g (0.9-1.8). After initiation of sparsentan, UPCR significantly decreased (P < 0.0001) to a median of 0.85 g/g (0.42-1.15) in the 2-week follow-up and further declined (P = 0.001) to a median of 0.60 g/g (0.32-0.82) after 14 weeks, equivalent to a relative reduction in proteinuria up to 62% (45-74). A similar significant reduction was observed for the urine albumin/creatinine ratio. No drug-related serious adverse events were reported.

Conclusions

In this real-world setting, sparsentan shows a significant impact on proteinuria, leading to a relative reduction of 62% in UPCR after 14 weeks and beyond, even in patients already receiving SGLT2 inhibitors.

Targeting endothelin signaling in podocyte injury and diabetic nephropathy-diabetic kidney disease

Despite advances in diabetes management, there is an urgent need for novel therapeutic strategies since the current treatments remain insufficient in halting the progression of diabetic nephropathy-diabetic kidney disease (DN-DKD). This review is mainly addressed on the pivotal role of endothelin-1 in the pathophysiology of DN, with a specific focus on its effects on podocytes and the glomerular filtration barrier. Endothelin-1 promotes mesangial cell proliferation, sclerosis, and direct podocyte injury via the activation of endothelin type A and B receptors, that drive the progression of glomerulosclerosis in DN-DKD. Endothelin receptor antagonists, including drugs like atrasentan and sparsentan, have demonstrated nephroprotective effects in experimental models by reducing proteinuria and podocyte injury. The therapeutic potential to slow the progression of DN to end-stage kidney disease (ESKD) of these endothelin receptor antagonists in clinical practice is currently under evaluation. However, fluid retention and increased risk of heart failure associated with endothelin receptor antagonists need careful consideration. This review aims to provide an in-depth analysis of the pathophysiological role of endothelin and the emerging therapeutic implications of targeting this pathway in DN-DKD and discusses efficacy, safety, and the possibility of combining the new generation of endothelin receptor antagonists with the standard treatment of CKD and DN-DKD.

Unraveling Sex Differences in Kidney Health and CKD: A Review of the Effect of Sex Hormones

Sexual dimorphism plays an important role in the pathogenesis and progression of CKD. Men with CKD often exhibit faster kidney function decline, leading to higher rates of kidney failure and mortality compared with women. Studies suggest that sex hormones may influence this apparent dimorphism, although the mechanisms underlying these influences remain poorly understood. In this review, we first summarize recent findings on sex differences in the prevalence and progression of CKD. Subsequently, we will focus on ( 1 ) the role of sex hormones in these sex differences, ( 2 ) kidney structural and hemodynamic differences between men and women, ( 3 ) the influence of sex hormones on pathophysiological processes leading to kidney disease, including glomerular hyperfiltration and key pathways involved in kidney inflammation and fibrosis, and finally, focus on the consequences of the underrepresentation of women in clinical trials. Understanding these sex differences is critical for advancing precision medicine and improving outcomes for both men and women with CKD.

The Global Kidney Patient Trials Network and the CAPTIVATE Platform Clinical Trial Design: A Trial Protocol

Importance

Chronic kidney disease (CKD) is a global health priority affecting almost 1 billion people. New therapeutic options and clinical trial innovations such as adaptive platform trials provide an opportunity to efficiently test combination therapies.

Objective

To describe the design and baseline results of the Global Kidney Patient Trials Network (GKPTN) and the design and structure of the global adaptive platform clinical trial Chronic Kidney Disease Adaptive Platform Trial Investigating Various Agents for Therapeutic Effect (CAPTIVATE) to find new therapeutic options and treatments for people with kidney disease.

Design, Setting, and Participants

The GKPTN is a multicenter registry that started in May 2020 and is ongoing, while CAPTIVATE is a multicenter, multifactorial, phase 3, placebo-controlled adaptive platform randomized clinical trial that includes patients with CKD. The first participant was randomized in September 2024. The GKPTN recruits patients from kidney and endocrinology practices, and CAPTIVATE aims to recruit patients from GKPTN sites where possible. Both the GKPTN and CAPTIVATE recruit patients with nondialysis CKD.

Intervention

CAPTIVATE will test several investigational agents or combinations of agents, beginning with a mineralocorticoid receptor antagonist.

Main Outcomes and Measures

The GKPTN monitors clinical characteristics, treatment, and outcomes to identify eligible clinical trial participants and provide a contemporary global picture of patients with CKD. The primary outcome of CAPTIVATE is to identify investigational agents or combinations of agents to reduce the rate of chronic estimated glomerular filtration rate (eGFR) decline. The default maximum sample size per treatment arm in each domain, based on bayesian simulations, is 500 participants, providing approximately 90% power to detect a clinically meaningful improvement of 2.6 mL/min/1.73 m2 in eGFR at the end of the 104-week study period.

Results

The GKPTN has enrolled 4334 patients across 119 sites in 8 countries (US, Australia, Argentina, China, Italy, Canada, Spain, and Japan). The mean (SD) participant age at enrollment was 64.5 (16.2) years, 2542 participants (58.7%) were female, and diabetic kidney disease was most frequently reported among patients for CKD etiology (1875 [43.3%]). Among the participants, the mean (SD) eGFR was 52.9 (29.3) mL/min/1.73 m2, and the median urinary albumin-to-creatinine ratio was 89 mg/g (coefficient of variation, 20-420 mg/g). In the GKPTN cohort, the mean eGFR decline was steeper among participants with a baseline eGFR of 60 mL/min/1.73 m2 or more (-2.29 [95% CI, -3.14 to -1.44]) compared with those with an eGFR of less than 60 mL/min/1.73 m2 (-1.16 [95% CI, -1.77 to -1.44]) and was progressively steeper in more severe albuminuria subgroups.

Conclusions and Relevance

The GKPTN registry and the CAPTIVATE trial have the potential to expand and optimize therapeutic options for people with CKD using an adaptive platform clinical trial design.

Trial Registration

ClinicalTrials.gov Identifiers: NCT04389827 and NCT06058585.

Beta-carotene ameliorates diabetic nephropathy in rats: involvement of AMPK/SIRT1/autophagy pathway

OBJECTIVE

This study aimed to demonstrate the protective effect of beta-carotene against STZ-induced DN in rats and explore the possible underlying mechanisms that may have mediated such condition.

MATERIAL AND METHODS

Wistar rats were allocated into four groups. Normal group received distilled water for 3 weeks. The other three groups were rendered diabetic by an intraperitoneal dose of STZ (50 mg/kg), 48 h later, group 2: received the vehicle and served as control, groups (3 &4) received orally beta-carotene in doses of 10 and 20 mg/kg, respectively for 3 weeks. Then serum and renal tissue were collected for biochemical, molecular, immunohistopathological, and histopathological examination.

RESULTS

Beta-carotene ameliorated the reduction in body weight, reduced blood glucose, elevated serum insulin, reduced blood urea nitrogen, and serum creatinine levels. Beta-carotene elevated phosphorylated 5' adenosine monophosphate-activated protein kinase (p-AMPK)/AMPK, alleviated phosphorylated mammalian target of rapamycin (p-mTOR)/mTOR, reduced interleukin 1 beta (IL-1β), increased Beclin 1, LC3II/LC3I, and reduced p62 renal contents. Moreover, it elevated renal SIRT1 gene expression and reduced renal tumor necrosis factor-alpha (TNF-α) and caspase-3 protein expressions.

CONCLUSION

Beta-carotene exerted renoprotective effect against STZ-induced DN and histopathological alterations through alleviating hyperglycemia, attenuating inflammation, activating AMPK/SIRT1/autophagy pathway, and combating apoptosis.

Current perspectives and trends of the research on hypertensive nephropathy: a bibliometric analysis from 2000 to 2023

Hypertensive nephropathy continues to be a major cause of end-stage renal disease and poses a significant global health burden. Despite the staggering development of research in hypertensive nephropathy, scientists and clinicians can only seek out useful information through articles and reviews, it remains a hurdle for them to quickly track the trend in this field. This study uses the bibliometric method to identify the evolutionary development and recent hotspots of hypertensive nephropathy. The Web of Science Core Collection database was used to extract publications on hypertensive nephropathy from January 2000 to November 2023. CiteSpace was used to capture the patterns and trends from multi-perspectives, including countries/regions, institutions, keywords, and references. In total, 557 publications on hypertensive nephropathy were eligible for inclusion. China (n = 208, 37.34%) was the most influential contributor among all the countries. Veterans Health Administration (n = 19, 3.41%) was found to be the most productive institution. Keyword bursting till now are renal fibrosis, outcomes, and mechanisms which are predicted to be the potential frontiers and hotspots in the future. The top seven references were listed, and their burst strength was shown. A comprehensive overview of the current status and research frontiers of hypertensive nephropathy has been provided through the bibliometric perspective. Recent advancements and challenges in hypertensive nephropathy have been discussed. These findings can offer informative instructions for researchers and scholars.

The association between bone density of lumbar spines and different daily protein intake in different renal function

BACKGROUND

Low protein intake (LPI) has been suggested as a treatment for chronic kidney disease (CKD). However, protein intake is essential for bone health.

METHODS

We studied the database of the National Health and Nutrition Examination Survey, 2005-2010. Basic variables, metabolic diseases, and bone density of different femoral areas were stratified into four subgroups according to different protein intake (DPI) (that is, <0.8, 0.8-1.0, 1.0-1.2, and >1.2 g/kg/day).

RESULTS

Significant differences were found among all lumbar area bone mineral density (BMD) and T-scores (p < 0.0001). There was an apparent trend between a decreasing BMD in the CKD groups with increasing DPI in all single lumbar spines (L1, L2, L3, and L4) and all L spines (L1-L4). Compared with DPI (0.8-1.0 g/day/kg), higher risks of osteoporosis were noticed in the subgroup of >1.2 g/day/kg over L2 (relative risk (RR)=1.326, 95% confidence interval (CI)=1.062-1.656), subgroup >1.2 g/day/kg over L3 (RR = 1.31, 95%CI = 1.057-1.622), subgroup <0.8 g/day/kg over L4 (RR = 1.276, 95%CI = 1.015-1.605), subgroup <0.8 g/day/kg over all L spines (RR = 11.275, 95%CI = 1.051-1.548), and subgroup >1.2 g/day/kg over all L spines (RR = 0.333, 95%CI = 1.098-1.618). However, a higher risk of osteoporosis was observed only in the non-CKD group. There was an apparent trend of higher DPI coexisting with lower BMD and T scores in patients with CKD. For osteoporosis (reference:0.8-1.0 g/day/kg), lower (<0.8 g/day/kg) or higher DPI (>1.2 g/day/kg) was associated with higher risks in the non-CKD group, but not in the CKD group.

CONCLUSIONS

In the CKD group, LPI for renal protection was safe without threatening L spine bone density and without causing a higher risk of osteoporosis.

Kinetics of endothelin-1 and effect selective ETA antagonism on ETB activation: a mathematical modeling analysis

Introduction

Endothelin-1 (ET-1) regulates renal and vascular function, but the clinical utility of selective ETA receptor antagonists has been limited due to associated fluid retention. The mechanisms underlying fluid retention remain poorly understood but could be a consequence of changes in ET-1 binding to the unantagonized ETB receptor, either through increased ET-1 or non-selective ETB.

Methods

A mathematical model of ET-1 kinetics was developed to quantify effects of ETA antagonist exposure and selectivity on concentrations of ET-1 and its complexes with ETA and ETB receptors. The model describes ET-1 production, tissue and plasma distribution, ETA and ETB receptor binding, and receptor-mediated clearance, and was calibrated and validated with human ET-1 infusion studies.

Results

The model confirmed the significant role of ETB in ET-1 clearance. By varying both drug ETA selectivity (Kib/Kia) and concentration over a wide range, simulations predicted that while selective ETA antagonist (selectivity >1) always decreased [ET1-ETA], the change in [ET1-ETB] was more complex. It increased up to 45% as drug concentrations approached and exceeded Kia, but the increase was diminished as drug concentration increased further and fell below baseline at high concentrations. The drug concentration required to cause a decrease in [ET1-ETB] was lower as ETA selectivity decreased.

Discussion

This is the first mechanistic mathematical model of ET-1 kinetics that describes receptor-mediated clearance, and the consequence of ETB blockade on ET-1 concentrations. It provides a useful tool that can coupled with experimental studies to quantitively understand and investigate this complex and dynamic system.

Pulmonary hypertension and chronic kidney disease: prevalence, pathophysiology and outcomes

Pulmonary hypertension (PH) is common in patients with chronic kidney disease (CKD) or kidney failure, with an estimated prevalence of up to 78% in those referred for right-heart catheterization. PH is independently associated with adverse outcomes in CKD, raising the possibility that early detection and appropriate management of PH might improve outcomes in at-risk patients. Among patients with PH, the prevalence of CKD stages 3 and 4 is estimated to be as high as 36%, and CKD is also independently associated with adverse outcomes. However, the complex, heterogenous pathophysiology and clinical profile of CKD-PH requires further characterization. CKD is often associated with elevated left ventricular filling pressure and volume overload, which presumably leads to pulmonary vascular stiffening and post-capillary PH. By contrast, a distinct subgroup of patients at high risk is characterized by elevated pulmonary vascular resistance and right ventricular dysfunction in the absence of pulmonary venous hypertension, which may represent a right-sided cardiorenal syndrome defined in principle by hypervolaemia, salt avidity, low cardiac output and normal left ventricular function. Current understanding of CKD-PH is limited, despite its potentially important ramifications for clinical decision making. In particular, whether PH should be considered when determining the suitability and timing of kidney replacement therapy or kidney transplantation is unclear. More research is urgently needed to address these knowledge gaps and improve the outcomes of patients with or at risk of CKD-PH.

Dual blockade of endothelin A and angiotensin II type 1 receptors with sparsentan as a novel treatment strategy to alleviate IgA nephropathy

INTRODUCTION

Although immunoglobulin A nephropathy (IgAN) had been discovered more than 50 years ago, 30-40% of IgAN patients still have primary glomerular disease that progresses to end-stage renal disease. However, various treatment strategies for IgAN have rapidly expanded in recent years to include endothelin (ET) receptor antagonists.

AREAS COVERED

In this review, we discuss the role of the ET-1/ETA receptor axis in the development of IgAN, especially focusing on the potential of sparsentan, a dual ET and angiotensin receptor antagonist as a novel therapy for IgAN.

EXPERT OPINION

Evaluation of the MEST-C score at the time of renal biopsy in IgAN is important in determining treatment strategies. If lesions are mainly in the acute phase, such as crescents, steroid therapy should be continued. However, if lesions are mainly in the chronic phase, such as glomerulosclerosis, sparsentan rather than steroid or angiotensin II receptor blocker alone may improve renal outcomes. Although further clinical studies are needed to back up these assumptions, appropriate combination of new drugs containing sparsentan and conventional drugs for IgAN treatment at the appropriate disease stage is expected to further inhibit the progression of renal damage.

The role of venous capacity in fluid retention with endothelin A antagonism: Mathematical modelling of the RADAR trial

BACKGROUND AND PURPOSE

Endothelin-1 (ET-1) receptor A (ETA) antagonists reduce proteinuria and prevent renal outcomes in chronic kidney disease (CKD) patients, but their utility has been limited because of associated fluid retention, resulting in increased heart failure risk. Understanding the mechanisms responsible for fluid retention could result in solutions that preserve renoprotective effects while mitigating fluid retention, but the complexity of the endothelin system has made identification of the underlying mechanisms challenging.

APPROACH

We utilized a previously developed mathematical model of ET-1 kinetics, ETA receptor antagonism, kidney function, haemodynamics, and sodium and water homeostasis to evaluate hypotheses for mechanisms of fluid retention with ETA antagonism. To do this, we simulated the RADAR clinical trial of atrasentan in patients with type 2 diabetes and CKD and evaluated the ability of the model to predict the observed decreases in haematocrit, urine albumin creatinine ratio (UACR), mean arterial pressure (MAP), and estimated glomerular filtration rate (eGFR).

BACKGROUND AND KEY RESULTS

An effect of ETA antagonism on venodilation and increased venous capacitance was found to be the critical mechanism necessary to reproduce the simultaneous decrease in both MAP and haematocrit observed in RADAR.

CONCLUSIONS AND IMPACT

These findings indicate that fluid retention with ETA antagonism may not be caused by a direct antidiuretic effect within the kidney but is instead be an adaptive response to venodilation and increased venous capacity, which acutely tends to reduce cardiac filling pressure and cardiac output, and that fluid retention occurs in an attempt to maintain cardiac filling and cardiac output.

The Dual Burden: Exploring Cardiovascular Complications in Chronic Kidney Disease

Chronic kidney disease (CKD) represents a significant global health challenge, affecting millions of individuals and leading to substantial morbidity and mortality. This review aims to explore the epidemiology, cardiovascular complications, and management strategies associated with CKD, emphasizing the importance of preventing cardiovascular disease and early intervention. CKD is primarily driven by conditions such as diabetes mellitus, hypertension, and cardiovascular diseases, which often coexist and exacerbate renal impairment. Effective management requires a multifaceted approach, including lifestyle modifications, pharmacological interventions, and regular monitoring. Dietary changes, such as sodium restriction and a controlled intake of phosphorus and potassium, play a vital role in preserving renal function. Pharmacological therapies, particularly angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and emerging agents like SGLT2 inhibitors, have shown efficacy in slowing disease progression and improving patient outcomes. Furthermore, patients undergoing dialysis face increased cardiovascular risk, necessitating comprehensive management strategies to address both renal and cardiac health. As the landscape of CKD treatment evolves, ongoing research into novel therapeutic options and personalized medical approaches are essential. This review underscores the urgent need for awareness, education, and effective preventive measures to mitigate the burden of CKD and enhance the quality of life for affected individuals.

Endothelin Inhibitors in Chronic Kidney Disease: New Treatment Prospects

The endothelin system is reported to play a significant role in glomerular and tubulointerstitial kidney disease. In the kidney, endothelins are produced in mesangial cells and the glomerular basement membrane by the endothelium and podocytes. The endothelin system regulates glomerular function by inducing proliferation, increasing permeability and in effect proteinuria, and stimulating inflammation, tubular fibrosis, and glomerular scarring. Endothelin A receptor antagonists have been proven to delay the progression of chronic kidney disease and play a protective role in immunoglobulin A nephropathy, focal segmental glomerulosclerosis, and diabetic nephropathy. There are several ongoing research studies with ETAR antagonists in nondiabetic nephropathy, Alport disease, vasculitis and scleroderma nephropathy, which results are promising. Some reports suggest that the endothelin system might contribute to ischemia-reperfusion injury, acute graft rejection and deterioration of graft function. Endothelin inhibition in renal transplantation and its influence on graft survival is the future direction needing further research. The most frequent side effects associated with ETAR antagonists is fluid retention. Additionally, it should be considered if selective ETAR antagonists therapy needs to be co-administered with sodium-glucose co-transporter 2 inhibitors, renin-angiotensin-aldosterone inhibitors or diuretics and which patients should be recruited to such treatment to minimize the risk of adverse outcomes.

SGLT2i and GLP1-RA exert additive cardiorenal protection with a RAS blocker in uninephrectomized db/db mice

Introduction

Diabetic Kidney Disease (DKD) is the main cause of end-stage renal disease in the developed world. The current treatment of the DKD with renin-angiotensin system (RAS) blockade does not totally halt the progression to end stage kidney disease. Currently, several drugs have shown to delay DKD progression such as sodium-glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like-1 receptor agonists (GLP-1RA). We hypothesized that by combining several drugs that prevent DKD progression on top of RAS blockade a synergistic effect would be achieved in terms of cardiorenal protection. In the present study, we analysed if the combination of a RAS blocker (ramipril) with a SGLT2i (empagliflozin) and/or GLP-1RA (semaglutide) in a type 2 diabetic mouse model could have add-on effects in kidney and heart protection.

Methods

Male and female uninephrectomized type 2 diabetic db/db mice were treated with empagliflozin and/or semaglutide on top of ramipril during 8 weeks. During the study body weight, water and food intake were weekly monitored, glycaemia biweekly and albuminuria and glomerular filtration rate (GFR) before and after the treatment. At the end of the experiment, kidney and heart were isolated for histological and gene expression studies as well as for intrarenal RAS state assessment.

Results

Semaglutide combined with ramipril and/or empagliflozin significantly decreased albuminuria but only when combined with both compounds, semaglutide further decreased blood glucose, glomerular hyperfiltration in male mice and glomerular mesangial matrix expansion. In kidney, only the triple treatment with empagliflozin, semaglutide and ramipril reduced the expression of the proinflammatory and profibrotic genes ccl2 and TGFß1. In addition, the combination of empagliflozin and semaglutide on top of RAS blockade was superior in decreasing cardiomyocyte hypertrophy and heart fibrosis in db/db mice.

Discussion

Our results suggest that the combination of SGLT2i with GLP-1RA is superior in cardiorenal protection in DKD than the drugs administered alone on top of RAS blockade.

Podocyte-targeted therapies - progress and future directions

Podocytes are the key target cells for injury across the spectrum of primary and secondary proteinuric kidney disorders, which account for up to 90% of cases of kidney failure worldwide. Seminal experimental and clinical studies have established a causative link between podocyte depletion and the magnitude of proteinuria in progressive glomerular disease. However, no substantial advances have been made in glomerular disease therapies, and the standard of care for podocytopathies relies on repurposed immunosuppressive drugs. The past two decades have seen a remarkable expansion in understanding of the mechanistic basis of podocyte injury, with prospects increasing for precision-based treatment approaches. Dozens of disease-causing genes with roles in the pathogenesis of clinical podocytopathies have been identified, as well as a number of putative glomerular permeability factors. These achievements, together with the identification of novel targets of podocyte injury, the development of potential approaches to harness the endogenous podocyte regenerative potential of progenitor cell populations, ongoing clinical trials of podocyte-specific pharmacological agents and the development of podocyte-directed drug delivery systems, contribute to an optimistic outlook for the future of glomerular disease therapy.

Clinical trial designs to assess treatment effects on glomerular filtration rate decline

Glomerular filtration rate (GFR) decline is used as surrogate endpoint for kidney failure. Interventions that reduce chronic kidney disease (CKD) progression often exert acute GFR reductions which differ from their long-term benefits and complicate the estimation of long-term benefit. Here, we assessed the utility of two alternative trial designs (wash-out design and active run-in randomized withdrawal design) that attempt to exclude the impact of acute effects. Post-hoc analyses of two clinical trials that characterized the effect of an intervention with acute reductions in GFR were conducted. The two trials included a wash-out period (EMPA-REG Outcome testing empagliflozin vs placebo) or an active run-in period with a randomized withdrawal (SONAR testing atrasentan vs placebo). We compared the drug effect on GFR decline calculated from the first on-treatment visit to the end of treatment (chronic slope in a standard randomized trial design) with GFR change calculated from randomization to end of wash out, or GFR change from treatment-specific baseline GFR values (GFR at start-of-run-in for placebo and end-of-run-in for atrasentan) until end-of-treatment. The effect of empagliflozin versus placebo on chronic GFR slope was 1.72 (95% confidence interval 1.49-1.94) mL/min/1.73 m2/year, similar to total GFR decline from baseline to the end of wash-out period using a linear mixed model 1.64 (1.44-1.85) mL/min/1.73 m2/year). The effect of atrasentan versus placebo on chronic GFR slope was 0.72 (0.32-1.11) mL/min/1.73 m2/year, similar to total slope from a single slope model when estimated from treatment specific baseline GFR values 0.77 (0.39-1.14) mL/min/1.73 m2/year). Statistical power of the two designs outperformed the standard randomized design. Thus, wash-out and active-run-in randomized-withdrawal trial designs are appropriate models to compute treatment effects on GFR decline.

Effects of Zibotentan Alone and in Combination with Dapagliflozin on Fluid Retention in Patients with CKD

Key Points

Increasing doses of the endothelin receptor antagonist zibotentan and lower eGFR were associated with a higher risk of fluid retention. The higher risk of fluid retention could be attenuated by the combination of zibotentan with the sodium-glucose cotransporter 2 inhibitor dapagliflozin.

Background

Endothelin receptor antagonists (ERAs) reduce albuminuria but are limited by fluid retention risk, particularly in patients with CKD. Combining ERAs with sodium-glucose cotransporter 2 (SGLT2) inhibitors, which have diuretic effects, offers a promising strategy to mitigate fluid retention. In this post hoc analysis of the Zibotentan and Dapagliflozin for the Treatment of CKD (ZENITH-CKD) trial, we assessed fluid dynamics in patients with CKD treated with the ERA zibotentan alone and in combination with the SGLT2 inhibitor dapagliflozin.

Methods

In the ZENITH-CKD trial, 508 patients with CKD (eGFR ≥20 ml/min per 1.73 m2 and a urinary albumin-creatinine ratio of 150–5000 mg/g) were randomized to treatment with placebo, dapagliflozin 10 mg plus placebo, zibotentan (0.25, 1.5, or 5 mg) plus dapagliflozin 10 mg, and zibotentan 5 mg plus placebo. We evaluated correlations between changes in fluid retention markers and bioimpedance-measured extracellular fluid in response to zibotentan treatment. We used Cox proportional hazards regression to assess the association between zibotentan/dapagliflozin treatment, baseline characteristics, and fluid retention and the relationship between zibotentan plasma exposure and fluid retention.

Results

After 3 weeks of treatment with zibotentan 0.25, 1.5, or 5 mg plus dapagliflozin 10 mg, changes in body weight (β =0.36 [95% confidence interval (CI), 0.26 to 0.45]) per kg, B-type natriuretic peptide (β =0.38 [95% CI, 0.22 to 0.54]) per doubling, and hemoglobin (β =−0.29 [95% CI, −0.48 to −0.10]) per g/dl were independently associated with changes in extracellular fluid. Higher doses of zibotentan were associated with significantly higher risk of fluid retention compared with dapagliflozin alone (zibotentan 5 mg hazard ratio (HR) 8.50 [95% CI, 3.40 to 21.30]). The HR attenuated when zibotentan was combined with dapagliflozin (zibotentan/dapagliflozin 5/10 mg HR 3.09 [95% CI, 1.08 to 8.80], zibotentan/dapagliflozin 1.5/10 mg 2.70 [95% CI, 1.44 to 5.07], and zibotentan/dapagliflozin 0.25/10 mg HR 1.21 [95% CI, 0.50 to 2.91]). The risk of fluid retention was higher with higher zibotentan exposure and lower eGFR.

Conclusions

High doses of zibotentan were associated with a higher risk of fluid retention, which was attenuated with lower doses and the addition of dapagliflozin.

Clinical Trial registry name and registration number:

ZENITH-CKD Trial, NCT04724837 .

Correlation of Urinary Soluble CD163 Levels With Disease Activity and Treatment Response in IgA Nephropathy

Introduction

The TESTING trial demonstrated that corticosteroids reduce the risk of kidney failure in patients with IgA nephropathy (IgAN) but increase the risk of serious adverse events. Reliable noninvasive biomarkers are needed to identify patients who would benefit most from corticosteroid therapy. Previous studies suggest glomerular macrophage infiltration is associated with response to immunosuppressive therapy in IgAN and urinary soluble CD163 ([u-sCD163], a marker of alternatively activated macrophages [M2]c macrophage) is correlated with clinical remission in vasculitis. This study aims to investigate the association between u-sCD163 and response of steroids therapy in IgAN.

Methods

We measured u-sCD163 in patients from a large IgAN cohort and Chinese participants of the TESTING trial. The correlation of baseline or serial u-sCD163 and their response of corticosteroids therapy or kidney outcomes were investigated.

Results

In cross-sectional analysis, u-sCD163 levels correlated with kidney macrophage infiltration, especially in crescentic areas, and with active lesions. Subgroup analysis of the TESTING cohort showed higher levels u-sCD163 were associated with greater benefits from corticosteroids therapy in proteinuria remission (odds ratio, 35.56 [95% confidence interval, CI: 7.62-292.34] vs. 3.94 [95% CI: 1.39-12.93], P for interaction: 0.036). Corticosteroids therapy significantly reduced u-sCD163 levels at 6 months compared to placebo group (79% [interquartile range: 58%-91%] vs. 37% [-11% to 58%], P <0.001). There was no difference in the suppressive effects on u-sCD163 by either dosage of corticosteroids (full and reduced-dose). The suppression of u-sCD163 was significantly associated with a reduced risk of kidney progression events (adjusted hazard ratio: 0.52, 95% CI: 0.30-0.93, P = 0.027).

Conclusion

u-sCD163 is a reliable noninvasive biomarker associated with active pathological lesions in IgAN and can guide glucocorticoid therapy.

Chronic Kidney Disease Progression-A Challenge

Chronic kidney disease (CKD) is a progressive condition characterized by a continuous decline in renal function, independent of the initial cause of damage or external factors such as infection, inflammation, or toxins. The accurate measurement of renal function, typically assessed using the glomerular filtration rate (GFR), is crucial for managing CKD. The most accepted hypothesis for CKD progression is glomerular damage caused by hyperfiltration. Various factors can accelerate CKD progression, and several biomarkers have been identified to monitor this progression. Numerous studies have explored the risk factors associated with CKD progression, and some of these factors can be modified. Additionally, several drugs are now available that can reduce CKD progression. This review summarizes recent publications and highlights potential future research directions in CKD progression. It discusses the evolution of GFR measurement methods, the mechanisms driving CKD progression, and the latest findings on biomarkers and risk factors. Furthermore, it explores therapeutic strategies, including dietary modifications and pharmacological interventions, to slow CKD progression. Understanding these mechanisms and interventions is crucial for developing effective therapeutic strategies to prevent or slow CKD progression.