Selective Endothelin Receptor Antagonist Research Articles

Combination therapy for kidney disease in people with diabetes mellitus.

Diabetic kidney disease (DKD), defined as co-existing diabetes and chronic kidney disease in the absence of other clear causes of kidney injury, occurs in approximately 20-40% of patients with diabetes mellitus. As the global prevalence of diabetes has increased, DKD has become highly prevalent and a leading cause of kidney failure, accelerated cardiovascular disease, premature mortality and global health care expenditure. Multiple pathophysiological mechanisms contribute to DKD, and single lifestyle or pharmacological interventions have shown limited efficacy at preserving kidney function. For nearly two decades, renin-angiotensin system inhibitors were the only available kidney-protective drugs. However, several new drug classes, including sodium glucose cotransporter-2 inhibitors, a non-steroidal mineralocorticoid antagonist and a selective endothelin receptor antagonist, have now been demonstrated to improve kidney outcomes in people with type 2 diabetes mellitus. In addition, emerging preclinical and clinical evidence of the kidney-protective effects of glucagon-like-peptide-1 receptor agonists has led to the prospective testing of these agents for DKD. Research and clinical efforts are geared towards using therapies with potentially complementary efficacy in combination to safely halt kidney disease progression. As more kidney-protective drugs become available, the outlook for people living with DKD should improve in the next few decades.

Insulin resistance, kidney outcomes and effects of the endothelin receptor antagonist atrasentan in patients with type 2 diabetes and chronic kidney disease

BackgroundInsulin resistance (IR) is a pathophysiologic hallmark of type 2 diabetes and associated with the presence of chronic kidney disease (CKD). Experimental studies suggest that endothelin-1 increases IR. We assessed the association between IR and cardio-renal outcomes and the effect of the selective endothelin receptor antagonist atrasentan on IR in patients with type 2 diabetes and CKD.MethodsWe used data from the RADAR and SONAR trials that recruited participants with type 2 diabetes and CKD [eGFR 25–75 mL/min/1.73 m², urine albumin-to-creatinine ratio of 300–5000 mg/g]. IR was calculated using the homeostatic model assessment (HOMA-IR). The association between HOMA-IR and the pre-specified cardio-renal outcomes was assessed using multivariable Cox proportional hazards regression, and effects of atrasentan on HOMA-IR by a linear mixed effect model.ResultsIn the SONAR trial, each log-unit increase in HOMA-IR was associated with an increased risk of the composite cardio-renal outcome [hazard ratio 1.32 (95%CI 1.09,1.60; p = 0.004)], kidney outcome [hazard ratio 1.30 (95%CI 1.00,1.68; p-value = 0.048)], and the kidney or all-cause mortality outcome [hazard ratio 1.25 (95%CI 1.01,1.55; p-value = 0.037)]. After 12 weeks treatment in the RADAR trial (N = 123), atrasentan 0.75 mg/day and 1.25 mg/day compared to placebo reduced HOMA-IR by 19.1 (95%CI -17.4, 44.3) and 26.7% (95%CI -6.4, 49.5), respectively. In the SONAR trial (N = 1914), atrasentan 0.75 mg/day compared to placebo reduced HOMA-IR by 9.6% (95%CI 0.6, 17.9).ConclusionsMore severe IR is associated with increased risk of cardio-renal outcomes. The endothelin receptor antagonist atrasentan reduced IR.Trial registrationRADAR trial (Reducing Residual Albuminuria in Subjects With Diabetes and Nephropathy With AtRasentan): NCT01356849.SONAR trial (The Study Of Diabetic Nephropathy With AtRasentan) NCT01858532.

Endothelin-1, over-expressed in SOD1G93A mice, aggravates injury of NSC34-hSOD1G93A cells through complicated molecular mechanism revealed by quantitative proteomics analysis.

Endothelin-1 (ET-1), a secreted signaling peptide, is suggested to be involved in multiple actions in various tissues including the brain, but its role in amyotrophic lateral sclerosis (ALS) remains unknown. In this study, we detected the expression changes as well as the cellular localization of ET-1, endothelin A (ET-A) and endothelin B (ET-B) receptors in spinal cord of transgenic SOD1-G93A (TgSOD1-G93A) mice, which showed that the two ET receptors (ET-Rs) expressed mainly on neurons and decreased as the disease progressed especially ET-B, while ET-1 expression was up-regulated and primarily localized on astrocytes. We then explored the possible mechanisms underlying the effect of ET-1 on cultured NSC34-hSOD1G93A cell model. ET-1 showed toxic effect on motor neurons (MNs), which can be rescued by the selective ET-A receptor antagonist BQ-123 or ET-B receptor antagonist BQ-788, suggesting that clinically used ET-Rs pan-antagonist could be a potential strategy for ALS. Using proteomic analysis, we revealed that 110 proteins were differentially expressed in NSC34-hSOD1G93A cells after ET-1 treatment, of which 54 were up-regulated and 56 were down-regulated. Bioinformatic analysis showed that the differentially expressed proteins (DEPs) were primarily enriched in hippo signaling pathway-multiple species, ABC transporters, ErbB signaling pathway and so on. These results provide further insights on the potential roles of ET-1 in ALS and present a new promising therapeutic target to protect MNs of ALS.

Arterial stiffness, endothelial dysfunction and impaired fibrinolysis are pathogenic mechanisms contributing to cardiovascular risk in ANCA-associated vasculitis

Cardiovascular disease is a complication of systemic inflammatory diseases including anti-neutrophil cytoplasm antibody-associated vasculitis (AAV). The mechanisms of cardiovascular morbidity in AAV are poorly understood, and risk-reduction strategies are lacking. Therefore, in a series of double-blind, randomized case-control forearm plethysmography and crossover systemic interventional studies, we examined arterial stiffness and endothelial function in patients with AAV in long-term disease remission and in matched healthy volunteers (32 each group). The primary outcome for the case-control study was the difference in endothelium-dependent vasodilation between health and AAV, and for the crossover study was the difference in pulse wave velocity (PWV) between treatment with placebo and selective endothelin-A receptor antagonism. Parallel invitro studies of circulating monocytes and platelets explored mechanisms. Compared to healthy volunteers, patients with AAV had 30% reduced endothelium-dependent vasodilation and 50% reduced acute release of endothelial active tissue plasminogen activator (tPA), both significant in the case-control study. Patients with AAV had significantly increased arterial stiffness (PWV: 7.3 versus 6.4 m/s). Plasma endothelin-1 was two-fold higher in AAV and independently predicted PWV and tPA release. Compared to placebo, both selective endothelin-A and dual endothelin-A/B receptor blockade reduced PWV and increased tPA release in AAV in the crossover study. Mechanistically, patients with AAV had increased platelet activation, more platelet-monocyte aggregates, and altered monocyte endothelin receptor function, reflecting reduced endothelin-1 clearance. Patients with AAV in long-term remission have elevated cardiovascular risk and endothelin-1 contributes to this. Thus, our data support a role for endothelin-blockers to reduce cardiovascular risk by reducing arterial stiffness and increasing circulating tPA activity.

Research in Brief

Edward Stern and colleagues conducted a three-part study to assess the safety and efficacy of zibotentan, a highly selective endothelin receptor antagonist, in systemic sclerosis-associated chronic kidney disease. 13 patients with an estimated glomerular filtration rate (eGFR) greater than 45 mL/min were randomly assigned (1:1) to zibotentan (n=6) or placebo (n=7) for 26 weeks. No effect was seen on serum VCAM1, but eGFR increased in patients receiving zibotentan and decreased in those receiving placebo.

FC052: Atrasentan for the Treatment of IGA Nephropathy: Interim Results from the Affinity Study

Abstract BACKGROUND AND AIMS IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the developed world. Up to 40% of patients with IgAN are at risk of progressing to end-stage kidney disease (ESKD), with proteinuria being a strong predictor of disease progression. Treatments that reduce proteinuria in IgAN are accompanied by eGFR preservation and improved kidney outcomes.[1] Endothelin A (ETA) receptor activation is a key driver of proteinuria, inflammation and fibrosis in patients with glomerular diseases.[2] Therefore, ETA receptor blockade has potential to be of therapeutic benefit for patients with proteinuric glomerular diseases, including IgAN. Atrasentan, a potent and selective ETA receptor antagonist that has demonstrated clinically significant reductions in proteinuria and risk of ESKD in a study of over 5300 patients with diabetic kidney disease (DKD), represents a potential therapy to reduce proteinuria and preserve kidney function in patients with IgAN and other glomerular diseases.[3] AFFINITY is a global, phase 2, open-label basket study to evaluate the efficacy and safety of atrasentan in patients with proteinuric glomerular diseases due to IgAN, Alport syndrome, focal segmental glomerulosclerosis and DKD. Here we present interim results from the first 17 patients enrolled in the IgAN cohort of the AFFINITY study, through week 12 of treatment. METHOD Approximately 20 patients will be enrolled in the IgAN cohort. They must have biopsy proven IgAN, be receiving a maximally tolerated and stable dose of renin angiotensin system inhibitor and have a urine protein creatinine ratio [UPCR] between 0.5 and <1.0 g/g from a first morning void urine sample. Patients are treated orally with 0.75 mg atrasentan daily. The primary endpoint is the change in 24-h UPCR from baseline to Week 12. Key exploratory endpoints include changes in eGFR from baseline to Week 56. RESULTS A total of 17 patients have enrolled in the IgAN cohort as of 4 January 2022. A total of 12 and 8 patients have completed visits through Week 6 and Week 12, respectively. The median age is 47 years and 41% are women. The geometric mean (GM) baseline proteinuria is 1.2 g/day, and median eGFR is 41 mL/min/1.73 m2 (Table 1). The 8 patients on treatment through Week 12 had a GM % reduction from baseline in 24-h UPCR of 43.6% [95% confidence interval (95% CI) 29.0–55.2] (Figure 1). Pharmacokinetic data are currently available for nine patients and showed a mean trough plasma atrasentan concentration in the targeted therapeutic range. Adverse events (AE) were observed in nne patients (53%), all mild or moderate in severity, most of which have resolved. One patient experienced an unrelated serious adverse event of traffic accident without long-term injuries. All patients remain on treatment with study drug except for one patient who discontinued drug due to an unrelated AE at week 13. CONCLUSION Treatment of patients with IgAN with atrasentan in addition to standard of care provided a >43% GM reduction in proteinuria after 12 weeks and was well tolerated, strongly supporting a key role of the endothelin pathway in the pathogenesis of IgAN. The ongoing phase 3 ALIGN study for patients with IgAN and proteinuria ≥1g/day will provide further assessment of the proteinuria lowering effects of atrasentan in this high-risk patient population.

MO264: Selective Endothelin a Receptor Antagonist Atrasentan Attenuates Mesangial Cell Injury, Proteinuria and intra-renal proliferative, inflammatory and Fibrotic Transcriptional Networks in a Rat Model of Mesangioproliferative Glomerulonephritis

Abstract BACKGROUND AND AIMS Mesangial cell (MC) activation, characterized by excess proliferation and extra-cellular matrix deposition is the initiating intra-renal event in the pathogenesis of mesangioproliferative glomerulonephritis (MPGN), including IgA nephropathy (IgAN). However, the molecular mechanisms responsible for MC activation and the subsequent podocyte crosstalk resulting in proteinuria have not been well defined. The objective of this study was to determine the role of the endothelin A (ETA) receptor in MC activation, proteinuria and pathogenic intra-renal transcriptional responses in a rat model of MPGN, using atrasentan, a potent and selective ETA antagonist. METHOD MPGN was induced in male Wistar rats by a single IV injection of anti-Thy1.1 antibody (0.5 mg/kg) on day 0. Rats were randomized to receive atrasentan (10 mg/kg, po bid) or vehicle control beginning on Day 1 through Day 7. UPCR was measured on Days 1, 3, 5 and 7; on Day 7, kidneys were fixed, stained and evaluated by light microscopy using a semi-quantitative grading scale by a pathologist, blinded to treatment allocations. RNA-seq was performed on flash-frozen kidney cortex and analyzed using DESeq2 to identify differentially expressed genes followed by gene set enrichment analysis to identify dysregulated transcriptional networks that were cross-validated to the glomerular transcriptome of kidney biopsy samples from IgAN patients (GSE104066). Cell type-specific signatures were derived from a scRNA-seq dataset (GSE171314) from IgAN patients. RESULTS Glomerular injury was characterized histologically by prominent mesangial hypercellularity and matrix expansion, glomerular adhesions, segmental mesangiolysis and glomerulosclerosis, and was significantly attenuated by atrasentan. Tubular injury, including protein casts, tubular degeneration, tubular dilation and interstitial fibrosis, was also observed in the model, although more modest and likely secondary to the glomerular injury, and was also significantly attenuated by atrasentan. The targeted mesangial injury induced by anti-Thy1.1 also resulted in significant proteinuria, which was substantially reduced by atrasentan (Fig. 1). In addition, atrasentan significantly attenuated the increase in kidney weight, likely reflective of the reduced mesangial proliferation, matrix expansion and accompanying inflammation observed histologically. Induction of MPGN in rats was transcriptionally characterized by a downregulation of metabolism gene networks and upregulation of networks associated with proliferation, inflammation and fibrosis, consistent with the hallmark genesets dysregulated in the glomeruli of IgAN patients (Fig. 2). Atrasentan downregulated these intra-renal proliferative, inflammatory and fibrotic transcriptional networks and upregulated metabolism networks (Fig. 2). Analysis using cell-type specific signatures derived from scRNA-seq data from IgAN patients, suggests that atrasentan treatment attenuates anti-Thy1.1-induced gene expression changes in multiple cell types, including mesangial cells, the target cell of injury in MPGN. In addition, although anti-Thy1.1 primarily induces glomerular injury, there was a strong transcriptional signature of failed repair in the proximal tubules, which was attenuated by atrasentan. CONCLUSION This study suggests an important role of the ETA receptor in MC activation, subsequent proteinuria and activation of pathogenic proliferative, inflammatory and fibrotic intra-renal transcriptional networks in MPGN. This further supports the therapeutic potential of atrasentan, a selective ETA receptor antagonist, to attenuate mesangial cell activation, proteinuria and pathogenic intra-renal signaling in MPGNs such as IgAN.

POS-544 Atrasentan in Patients with Proteinuric Glomerular Diseases (The AFFINITY Study)

Glomerular diseases are a leading cause of morbidity and mortality worldwide and are characterized by proteinuria, a strong predictor of disease progression and end-stage kidney disease. Currently, there are limited therapies and despite the recent approval of sodium glucose co-transporter 2 inhibitors (SGLT2i), residual risk remains. It is known that endothelin A (ETA) receptor activation drives glomerular injury, inflammation, and fibrosis through a common pathogenic pathway. Atrasentan, a potent and selective ETA receptor antagonist that has shown clinically significant reduction in proteinuria and risk of kidney failure in a study of over 5,300 patients with diabetic kidney disease (DKD), represents a promising therapy to reduce proteinuria and preserve kidney function in proteinuric glomerular diseases.

Effects of Selective Endothelin Receptor Antagonist on Vegf Signaling System in Diabetic Penis: A Possible Clinical Implication for Diabetes Induced Erectile Dysfunction

Erectile dysfunction (ED) affects around 50 percent of male diabetic patients due to vascular and neuropathic complications arising from diabetes. Vascular endothelial growth factor (VEGF) has been extensively investigated for its pathogenic relevance in various diabetes complications, and we have already noted that VEGF signaling is significantly reduced at the insulin-resistant stage in the penis of type II diabetic rat model. The present research used a three-week streptozotocin (STZ)-induced diabetic (DM) rat model to determine the expression of VEGF with NO mechanism in penile tissue and subsequently investigated its impact endothelin antagonism on these shifts. Citrate saline vehicle or STZ (65 mg/kg IP) was administered to male Sprague-Dawley rats (weight 453 ± 23 g). Hyperglycemia confirmed diabetes, and then after 1 week of diabetes, animals were divided into receiving endothelin-A (ET-A) receptor antagonists (TA-0201, 1 mg/kg) or saline by osmotic minipump for 2 weeks and then sacrificed. Significantly improved glucose levels in DM rats (405 ± 103 mg/dL) relative to non-DM rats (120 ± 8 mg/dL) and higher local ET-1 levels in DM penis by 20% are observed. A 30 percent decline in penile tissue expression of VEGF was observed in DM rats and improved by an antagonist with ET. Penile NO and eNOS levels in DM rats decreased, while ET-A receptor antagonist significantly increased. Therefore, we infer that ET antagonism seemed able to restore the down-regulated VEGF and was possibly efficient in restoring the decreased levels of NO and eNOS in DM.

Ambrisentan use in a HIV-1 infected patient with end-stage renal disease and pulmonary hypertension: minimal removal by hemodialysis - a case report

BackgroundAmbrisentan is a selective endothelin receptor antagonist used for the treatment of pulmonary arterial hypertension (PAH). Little is known about ambrisentan removal by hemodialysis in patients with end-stage renal disease (ESRD).Case presentationA 53-year-old woman with HIV/hepatitis C virus (HCV) co-infection, PAH and ESRD on regular hemodialyis was admitted in our hospital due to refractory heart failure while on treatment with bosentan (125 mg twice daily) and tadalafil (20 mg once daily) for PAH and antiretroviral treatment (cART) including darunavir/cobicistat (800/150 mg once daily). Excessive exposure to bosentan due to drug interactions between bosentan and darunavir/cobicistat was suspected. Bosentan was replaced by ambrisentan, with progressive improvement in her clinical condition. Pre- and postdialyzer cocentrations of ambrisentan in plasma were determined and hemodialysis extraction ratio for ambrisentan was 2%.ConclusionsOur results suggest that hemodialysis results in minimal ambrisentan removal, and therefore no specific ambrisentan dosage adjustment seems to be required in ESRD patients undergoing hemodialysis.

Comparison of the protective effects of selective endothelin-a receptor antagonist, ambrisentan, and dual endothelin-A/B receptor antagonist, bosentan, in experimental renal ischemia reperfusion injury.

This study aims to compare the protective effects of ambrisentan, a selective endothelin typeA receptor antagonist, and bosentan, a dual endothelin typeA/B receptor antagonist, on experimental renal ischemia reperfusion injury. The study sample consisted of 21 female rats, which were divided into 3 groups: Control, Ambrisentan and Bosentan. For the ischemia-reperfusion injury model, left‑kidney nephrectomy was performed after sacrificing the animals. In the immunohistochemical examination, caspase-3 was examined, and then the apoptotic index was determined. In the biochemical examination, the activities of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase, and the levels of nitrite (NOx), TNF-α, and IL-1β were determined. There were statistically significant differences between the groups in terms of total injury score grade in range of 0‒3 (p=0.001).The glomerular and tubular apoptotic indices were higher in the control group as compared to those of the ambrisentan and bosentan groups (p=0.001).There were no statistically significant differences in terms of SOD, CAT, GPx, MDA, IL-1β and TNF-α measurements among the groups (p>0.05). In the experimentally created renal ischemia reperfusion model, both ambrisentan and bosentan increased the NOx level, decreased the apoptosis, and protected the kidney from renal ischemia reperfusion injury. However, no significant superiority was found between ambrisentan and bosentan in terms of their protective effects (Tab. 3, Fig. 2, Ref. 31).

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

Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18-85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR) 25-75 mL/min per 1·73 m2 of body surface area, and a urine albumin-to-creatinine ratio (UACR) of 300-5000 mg/g who had received maximum labelled or tolerated renin-angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders) were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days) or end-stage kidney disease (eGFR <15 mL/min per 1·73 m2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure) in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325) or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4-2·9). 79 (6·0%) of 1325 patients in the atrasentan group and 105 (7·9%) of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR] 0·65 [95% CI 0·49-0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%) of 1325 patients in the atrasentan group and 34 (2·6%) of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85-2·07]; p=0·208). 58 (4·4%) patients in the atrasentan group and 52 (3·9%) in the placebo group died (HR 1·09 [95% CI 0·75-1·59]; p=0·65). Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. AbbVie.

Role of ambrisentan (selective endothelin-A receptor antagonist) on cigarette smoke exposure induced cognitive impairment in Danio rerio

BackgroundCigarette smoke is exogenous modifiable factors to changes the neurovascular complication. The chronic exposure of cigarette smoke enhances neurocognitive dysfunction. AimsThe present study is focused on evaluating the role of ambrisentan (selective endothelin-A receptor antagonist) on cigarette smoke-induced cognitive impairment in Danio rerio. Main methodsThe cognitive dysfunction was developed by cigarette smoke exposure (CSE; 10 min in 25 ml of CSE per day) for five days. The selective endothelin-A receptor antagonist i.e., ambrisentan (2.5 to 5 mg/kg; i.p. for five consecutive days) was used for testing of CSE induced cognitive dysfunction. In addition, treatment of reference drug i.e., donepezil (10 mg/kg; i.p. for five consecutive days) was used for this cognitive function study. The cognitive functions were assessed by light and dark chamber; color recognition; partition preference; horizontal compartment; and T-Maze tests. Further, the CSE induced biomarkers changes of the zebrafish brain samples were estimated. Key findingsThe treatment of ambrisentan showed a potential ameliorative effect against the CSE induced cognitive functions along with attenuation of biochemical changes. The results are comparable to donepezil-treated groups. SignificanceTherefore, ambrisentan can be considered for the attenuation of CSE induced impairment neurocognitive functions due to its reduction of free radical scavenging and neuroinflammatory actions as well as regulation of cholinergic neurotransmitter functions.

Isolation, identification, characterization, synthesis and quality control strategy of new process-related impurities in ambrisentan

Ambrisentan is a highly selective endothelin-A receptor antagonist for the treatment of pulmonary arterial hypertension (PAH). The analysis of the process-related impurities will help not only to optimize the process parameters but also to develop reasonable analytical methods and set the quality standard for a quality control strategy in pharmaceutical manufacturing. During the manufacture of ambrisentan, five unknown impurities were detected in pilot batches ranging from 0.05% to 0.15% by HPLC. All of these impurities were isolated and synthesized successfully and were identified and characterized by LC–MS, HRMS, ESI-MS/MS(Q-Tof), 1D-NMR (1H, 13C, DEPT) and 2D-NMR (COSY, HSQC, HMBC) techniques. The formation mechanisms that yield these impurities are discussed for the first time. Quality control strategies to deal with these impurities are developed to obtain bulk drug of ICH-grade quality.

Baseline characteristics and enrichment results from the SONAR trial.

AimThe SONAR trial uses an enrichment design based on the individual response to the selective endothelin receptor antagonist atrasentan on efficacy (the degree of the individual response in the urinary albumin‐to‐creatinine ratio [UACR]) and safety/tolerability (signs of sodium retention and acute increases in serum creatinine) to assess the effects of this agent on major renal outcomes. The patient population and enrichment results are described here.MethodsPatients with type 2 diabetes with an estimated glomerular filtration rate (eGFR) within 25 to 75 mL/min/1.73 m2 and UACR between 300 and 5000 mg/g were enrolled. After a run‐in period, eligible patients received 0.75 mg/d of atrasentan for 6 weeks. A total of 2648 responder patients in whom UACR decreased by ≥30% compared to baseline were enrolled, as were 1020 non‐responders with a UACR decrease of <30%. Patients who experienced a weight gain of >3 kg and in whom brain natriuretic peptide exceeded ≥300 pg/mL, or who experienced an increase in serum creatinine >20% (0.5 mg/dL), were not randomized.ResultsBaseline characteristics were similar for atrasentan responders and non‐responders. Upon entry to the study, median UACR was 802 mg/g in responders and 920 mg/g in non‐responders. After 6 weeks of treatment with atrasentan, the UACR change in responders was −48.8% (95% CI, −49.8% to −47.9%) and in non‐responders was −1.2% (95% CI, −6.4% to 3.9%). Changes in other renal risk markers were similar between responders and non‐responders except for a marginally greater reduction in systolic blood pressure and eGFR in responders.ConclusionsThe enrichment period has successfully identified a population with a profound UACR reduction without clinical signs of sodium retention in whom a large atrasentan effect on clinically important renal outcomes is possible. The SONAR trial aims to establish whether atrasentan confers renal protection.

Pulmonary hypertension: reasonable selection of specific therapy

Pulmonary hypertension is characterized with persistent increase in pulmonary vascular resistance leading to progressive worsening of right ventricular failure and death. The basis for pulmonary arterial hypertension is structural changes in pulmonary arteries and arterioles caused by endothelial dysfunction. Endothelin-1 is the main pathogenic trigger of pulmonary hypertension and potential target for therapeutic exposure. The efficacy of endothelin receptor antagonists is proved in various preclinical and clinical studies. In patients with pulmonary arterial hypertension, the efficacy of dual and selective endothelin receptor antagonists is comparable despite the varied activity against various receptors. Bosentan is the most widely used pulmonary vasodilator which improves exercise tolerance and decelerates disease progression.

Ambrisentan: a review of its use in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease defined by an elevation in pulmonary arterial pressure that can lead to right heart failure and death. Ambrisentan is a selective endothelin receptor antagonist approved for the treatment of idiopathic, heritable PAH and connective tissue disease-associated PAH. Ambrisentan has been shown to improve exercise capacity and hemodynamics with an acceptable side-effect profile. It has also proven to be safely used in combination with other PAH-specific medications, especially with phosphodiesterase-5 inhibitors. In the recent randomized trial, AMBITION, it was shown that upfront combination therapy of ambrisentan and tadalafil significantly decreased the risk of clinical failure compared with monotherapy. This review describes the drug profile of ambrisentan and its safety and efficacy in the treatment of PAH.

Long-Term Endothelin-A Receptor Antagonism Provides Robust Renal Protection in Humanized Sickle Cell Disease Mice.

Sickle cell disease (SCD)-associated nephropathy is a major source of morbidity and mortality in patients because of the lack of efficacious treatments targeting renal manifestations of the disease. Here, we describe a long-term treatment strategy with the selective endothelin-A receptor (ETA) antagonist, ambrisentan, designed to interfere with the development of nephropathy in a humanized mouse model of SCD. Ambrisentan preserved GFR at the level of nondisease controls and prevented the development of proteinuria, albuminuria, and nephrinuria. Microscopy studies demonstrated prevention of podocyte loss and structural alterations, the absence of vascular congestion, and attenuation of glomerulosclerosis in treated mice. Studies in isolated glomeruli showed that treatment reduced inflammation and oxidative stress. At the level of renal tubules, ambrisentan treatment prevented the increased excretion of urinary tubular injury biomarkers. Additionally, the treatment strategy prevented tubular brush border loss, diminished tubular iron deposition, blocked the development of interstitial fibrosis, and prevented immune cell infiltration. Furthermore, the prevention of albuminuria in treated mice was associated with preservation of cortical megalin expression. In a separate series of identical experiments, combined ETA and ETB receptor antagonism provided only some of the protection observed with ambrisentan, highlighting the importance of exclusively targeting the ETA receptor in SCD. Our results demonstrate that ambrisentan treatment provides robust protection from diverse renal pathologies in SCD mice, and suggest that long-term ETA receptor antagonism may provide a strategy for the prevention of renal complications of SCD.

Outcome of renal transplantation in IgA nephropathy

SGLT2 inhibitors have emerged as a key disease-modifying therapy to prevent the progression of chronic kidney disease (CKD). These agents prevent decline in kidney function through reduction in glomerular hypertension mediated through tubuloglomerular feedback independent of their effect on glycemic control. The proliferation of clinical trials on SGLT2 inhibitors has rapidly expanded the approved clinical indications for these agents beyond patients with diabetes mellitus (DM). We review the current indications for SGLT2 inhibitors in patients with and without diabetic kidney disease, including new evidence for use in patients with heart failure with or without reduced ejection fraction, stage 4 CKD, and chronic glomerulonephritis. The EMPA-KIDNEY trial was recently stopped early for efficacy suggesting that SGLT2 inhibitors may soon be indicated for patients with CKD without albuminuria. We review practical considerations for prescription of SGLT2 inhibitors, including the anticipated acute decline in estimated glomerular filtration rate (eGFR) on initiation, initiating the lowest dosage used in clinical trials, volume status considerations, and adverse event mitigation. Combination therapy in patients with DM may be considered with agents, including glucagon-like peptide-1 receptor agonists (GLP-1-RAs), novel mineralocorticoid receptor antagonists, and selective endothelin receptor antagonists to reduce residual albuminuria and cardiovascular risk.

Endothelin receptor antagonists for persistent pulmonary hypertension in term and late preterm infants.

Endothelin, a powerful vasoconstrictor, is one of the mediators in the causation of persistent pulmonary hypertension of the newborn (PPHN). Theoretically, endothelin receptor antagonists (ETRA) have the potential to improve the outcomes of infants with PPHN. To assess the efficacy and safety of ETRA in the treatment of PPHN in full-term, post-term and late preterm infants.To assess the efficacy and safety of selective ETRAs (which block only the ETA receptors) and non-selective ETRAs (which block both ETA and ETB receptors) separately. CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE and CINAHL databases were searched until December 2015. Randomised, cluster-randomised or quasi-randomised controlled trials were eligible. Two review authors independently searched the literature, selected the studies, assessed the risk of bias and extracted the data. A fixed-effect model was used for meta-analysis. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence. Two randomised controlled trials of ETRA met the inclusion criteria. Both studies utilized oral Bosentan. The first study was done in a setting where inhaled nitric oxide (iNO) therapy was not available. Forty-seven infants (≥ 34 weeks' gestation) were randomised to receive either Bosentan or placebo. The second study was a multicentre study where iNO therapy was the standard of care for PPHN. Twenty-one infants were randomised to receive either 'iNO plus Bosentan' or 'iNO plus placebo'.In the first study, there was no significant difference in the incidence of death before hospital discharge between the Bosentan and placebo groups (1/23 vs 3/14; RR 0.20, 95% CI 0.02 to 1.77; RD -0.17, 95% CI -0.40 to 0.06). A higher proportion of infants in the Bosentan group showed improvement in oxygenation index (OI) at the end of therapy (21/24 vs 3/15; RR 4.38, 95% CI 1.57 to 12.17; RD 0.68, 95% CI 0.43 to 0.92; number needed to treat for a beneficial outcome (NNTB) 1.5). The duration of mechanical ventilation was lower in the Bosentan group (4.3 ± 0.9 vs 11.5 ± 0.6 days; MD -7.20, 95% CI -7.64 to -6.76). There was no significant difference in adverse neurological outcomes at six months (0/23 vs 4/14; RR 0.07, 95% CI 0.00 to 1.20; RD -0.29, 95% CI -0.52 to -0.05). The study suffered from a high risk of attrition bias since 8/23 infants in the placebo group were excluded from various analyses. Since the protocol for the study could not be accessed, the study suffered from unclear risk of reporting bias.In the second study, there was no significant difference in the incidence of treatment failure needing extracorporeal membrane oxygenation (ECMO) between the 'iNO plus Bosentan' vs 'iNO plus placebo' groups (1/13 vs 0/8; RR 1.93, 95% CI 0.09 to 42.35; RD 0.08, 95% CI -0.14 to 0.30). There was no significant difference in the median time to wean from iNO ('iNO plus Bosentan': 3.7 days (95% CI 1.17 to 6.95); 'iNO plus placebo': 2.9 days (95% CI 1.26 to 4.23); P = 0.34). There were no significant differences in the OI 0, 3, 5, 12, 24, 48 and 72 hours of treatment between the groups. There were no significant differences in the time to complete weaning from mechanical ventilation (median 10.8 days (CI 3.21 to 12.21) versus 8.6 days (CI 3.71 to 9.66); P = 0.24). The study had unequal distribution to the Bosentan group (N = 13) and the placebo group (N = 8). The methods used for generating random sequence numbers and allocation concealment were unclear, resulting in unclear risk of selection bias.Both studies reported that Bosentan was well tolerated and no major adverse effects were noted. Data from the two studies was not pooled given the heterogenous nature of the clinical settings and the modalities used for the treatment of PPHN.Overall, the quality of evidence was considered low, given the small sample size of the included studies, the numerical imbalance between the groups due to randomisation and attrition, and unclear risk of bias on some of the important domains. There is inadequate evidence to support the use of ETRAs either as stand-alone therapy or as adjuvant to inhaled nitric oxide in PPHN. Adequately powered RCTs are needed.