Use Of Endothelin Receptor Antagonists Research Articles

Sunitinib-induced endocapillary proliferative glomerulonephritis with IgA2 deposit in addition to thrombotic microangiopathy: a case report

BackgroundSunitinib, a multi-targeted tyrosine kinase inhibitor, is used as a second-line therapy for gastrointestinal stromal tumors (GIST) resistant to imatinib. However, its impact on the vascular endothelial growth factor (VEGF) pathway can lead to significant toxicities, including hypertension and thrombotic microangiopathy (TMA).Case presentationThis case report describes a unique instance of a patient with metastatic GIST who developed endocapillary proliferative glomerulonephritis (EPGN) with IgA2 deposits and TMA following sunitinib treatment. The patient presented with severe hypertension, nephrotic syndrome, and acute kidney injury. Renal biopsy confirmed the diagnosis, revealing IgA2 deposits, which are not commonly associated with TMA. Discontinuation of sunitinib led to a rapid improvement in renal function and proteinuria. The potential mechanisms underlying sunitinib-induced glomerular injury may involve the blockade of VEGFR-1, affecting immune cell recruitment and function, and the disruption of the nitric oxide and endothelin systems, leading to endothelial damage and immune dysregulation. Management of these toxicities requires a personalized approach, with options ranging from symptomatic relief to drug discontinuation. The use of endothelin receptor antagonists and other therapeutic alternatives for GIST management is discussed.ConclusionsThis case highlights the complex interplay between the therapeutic effects of sunitinib and its potential renal and cardiovascular toxicities, emphasizing the need for close monitoring and effective management strategies to optimize patient outcomes.

Prescribing of endothelin receptor antagonists and riociguat in women of childbearing age in a large German claims database study

Use of endothelin receptor antagonists (ERAs) and riociguat, approved for treatment of pulmonary hypertension (PH), is contraindicated during pregnancy due to reported teratogenicity in animals. We aimed to investigate prescribing of these drugs in girls/women of childbearing age and to explore – as a secondary aim – the occurrence of pregnancies exposed to these drugs. Using the German Pharmacoepidemiological Research Database (GePaRD, claims data from 20% of the German population) we conducted cross-sectional analyses to determine prescribing prevalence of ERAs and riociguat between 2004 and 2019 and to characterize users and prescribing patterns. In a cohort analysis, we assessed the occurrence of pregnancies exposed to these drugs in the critical time window. Overall, we identified 407 women with ≥ 1 dispensation of bosentan between 2004 and 2019; the respective number was 73 for ambrisentan, 182 for macitentan, 31 for sitaxentan, and 63 for riociguat. In nearly all years, more than 50% of the girls/women were ≤ 40 years. Age-standardized prevalence was highest for bosentan (0.04/1000) in 2012 and 2013, followed by macitentan (0.03/1000) in 2018 and 2019. We observed 10 exposed pregnancies: 5 to bosentan, 3 to ambrisentan, and 2 to macitentan. The increased prevalence of macitentan and riociguat from 2014 onwards might reflect changes in PH treatment. Even though PH is a rare disease and pregnancy should be avoided in women with PH, particularly if they use ERAs, we identified pregnancies exposed to ERAs. Multi-database studies will be needed to assess the risk of these drugs on the unborn child.

Abstract 11428: A Comparison Between Endothelin Receptor Antagonists and Renal Denervation for Resistant Hypertension: A Systematic Review and Meta-Analysis of Sham and Placebo Controlled Trials

Introduction: Endothelin-1 causes vasoconstriction by activation of calcium flux in smooth muscle cells. Use of endothelin receptor antagonists (ERAs) has remained controversial. Renal denervation (RD) has also been investigated as a treatment option for resistant hypertension (RHTN). The efficacy of these two novel treatment strategies was compared. Methods: Placebo-controlled and sham-controlled randomized clinical trials testing ERA or RD as treatments for RHTN were selected. Prespecified subgroup analyses comparing the efficacy of ERA and RD were conducted for outcomes of 24-hour (hr) blood pressure (BP) and office BP. Results: Nine studies (3 ERA and 6 RD) were identified that included 1,708 participants (816 ERA and 892 RD). Cochran risk of bias assessment showed 72% of the domains to be low risk of bias for the ERA studies and 88% of the domains to be low risk of bias for the RD studies. The raw mean difference (RMD) between ERA and placebo control was statistically significant for 24-hr systolic (SBP) (-8.34 mmHg; 95% CI -11.51 to -5.81, 24-hr diastolic (DBP) (-6.77 mmHg; 95% CI -8.90 to -4.63), office SBP (-4.50 mmHg; 95% CI -6.92 to -2.08), and office DBP (-2.01 mmHg; 95% CI -2.13 to -1.88). The RMD between RD and sham control was not statistically significant for 24-hr SBP (-1.85 mmHg; 95% CI -3.88 to 0.18), 24-hr DBP (-0.67 mmHg; 95% CI -1.84 to 0.51), office SBP (-1.93 mmHg; 95% CI -5.17 to 1.31), and office DBP (-1.55 mmHg; 95% CI -3.43 to 0.33). The interaction between the treatment subgroups was statistically significant for 24-hr SBP and DBP, but not for office SBP and DBP. Discussion: ERAs had greater reduction in 24-hr and office BP compared to RD among patients with RHTN. Despite efficacy in reducing BP in RHTN, use of ERAs remains controversial given the cost and side effect profile. RD does not reduce BP among patients with RHTN. Medications are the optimal treatment for RHTN and sham controlled data showing efficacy is needed prior to widespread use and adoption of RD in RHTN.

The Seventeenth International Conference on Endothelin (ET-17).

The Seventeenth International Conference on Endothelin (ET-17) was held during 4-7 October 2021 and because of the SARS-CoV-2 pandemic it was held virtually. Sponsored by the American Physiological Society, ET-17 was held over 4 half-days, with exciting studies related to all organ systems presented. Since the Lancet article reporting the successful SONAR clinical trial with endothelin receptor A blockade in diabetic nephropathy, there has been renewed interest in the use of endothelin receptor antagonists in the treatment of a variety of diseases. From the rigorous preclinical studies to the latest clinical trials, ET-17 was full of exciting science, some of which is reported in this special issue. We welcomed new labs to the meeting and everyone left with the impression that ET-related research is a vibrant field with very significant discoveries being made.

Mechanistic study of the effect of Endothelin SNPs in microvascular angina - Protocol of the PRIZE Endothelin Sub-Study.

Microvascular angina is a common cause of ischemia with non-obstructive coronary arteries (INOCA) and limited therapeutic options are available to those affected. Endothelin-1 (ET-1) is a potent vasoconstrictor implicated in the pathophysiology of microvascular angina. A large randomised, double blinded, placebo controlled crossover trial, the PRecIsion medicine with ZibotEntan in microvascular angina (PRIZE) trial is currently underway, investigating an endothelin receptor antagonist - Zibotentan, as a new drug treatment for microvascular angina. The trial uses a 'precision medicine' approach by preferential selection of those with higher ET-1 expression conferred by the PHACTR1 minor G allele single nucleotide polymorphism (SNP). The incidence of this SNP occurs in approximately one third of the population therefore a considerable number of screened patients will be ineligible for randomisation and the treatment phase of the trial. In the PRIZE Endothelin (ET) Sub-Study, patients screened out of the PRIZE trial will be genotyped for other genetic variants in the ET-1 pathway. These will be correlated with phenotypic characteristics including exercise tolerance, angina severity and quantitative measures of microvascular function on cardiovascular MRI as well as mechanistic data on endothelin pathway signalling. The study will provide a comprehensive genotype and phenotype bio-resource identifying novel ET-1 genotypes to inform the potential wider use of endothelin receptor antagonists for this indication.

A network meta-analysis on the vasomodulators for portopulmonary hypertension

Abstract Background In patients with portopulmonary hypertension (PoPH) who are eligible and awaiting liver transplant, guidelines recommend lowering pulmonary pressures with vasomodulators as a bridge to transplant. However, efficacy of each vasomodulator class as a bridge to transplant remains unknown. Purpose This review compares the use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 inhibitors (PDE5-I), prostacyclin (PC) and combination therapy in its pulmonary pressure-lowering effects and pre-transplant mortality in this strictly selected subset of patients. Methods A search conducted on Medline and Embase on articles relating to vasomodulator use in PoPH for pulmonary pressure-lowering effects and mortality. Network analysis was conducted to summarize the evidence. Surface under the cumulative ranking curve (SUCRA) was used to rank treatments. Results Ten studies with 180 patients were included. SUCRA analysis demonstrated largest mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) lowering effects in ERA and combination therapy, followed by PDE5-I and PC. mPAP-lowering effects were largest in ERA (MD −19.440, CI: −62.280 to 23.400) and combination therapy (MD −18.223, CI: −29.677 to −6.770) when compared to PDE5-I (table 1). Pre-transplant mortality were comparable between ERA, PDE5-I and combination therapy. Both ERA (RR:0.349. CI: 0.137–0.891) and PDE5-I (RR: 0.279, CI: 0.091–0.854) had significantly lower mortality than PC (table 2). Conclusion This meta-analysis provides preliminary evidence that ERA have shown larger pulmonary pressure-lowering effects than PDE5-I in PoPH patients who were eligible for LT. Both ERA and PDE5-I have comparable mortality outcomes, with unfavorable outcomes in PC users. Funding Acknowledgement Type of funding sources: None.

Scleroderma nephropathy: unsolved problems

Kidney injury is a common pathology in the group of patients with systemic sclerosis. At least half of the patients show histological signs of it. Acute condition is known as scleroderma renal crisis. Although discussions regarding the risk factors for scleroderma renal crisis are open, most researchers consider the following factors: female sex, previous proteinuria and hypertension, the presence of anti-RNA polymerase III antibodies, and a decrease in lung diffusion capacity ≤75%. Diagnostic criteria for scleroderma renal crisis include an acute increase in blood pressure, accompanied by acute renal failure and abnormalities in the urinary sediment, anemia, and thrombocytopenia. Treatment of scleroderma renal crisis entails decreasing blood pressure, mainly with short-acting angiotensin-converting enzyme inhibitors, followed by selecting effective antihypertensive therapy. Further research of new treatment approaches is being carried on: the use of endothelin receptor antagonists (bosentan), monoclonal antibodies against the complement component 5 (eculizumab). Despite the approved strategies for identifying risk factors for scleroderma renal crisis development and treatment approaches, this group of patients is still characterized by high rates of mortality, the need for renal replacement therapy, and kidney transplantation. Thus, the problem of kidney injury in systemic sclerosis remains relevant.

Endothelin receptor B controls the production of fibroblast growth factor 23.

Endothelin-1 (ET-1) is a member of the endothelin family of peptide hormones first discovered as endothelium-derived mediators regulating vascular tone. ET-1 also regulates the proliferation and differentiation of bone cells that synthesize fibroblast growth factor 23 (FGF23). FGF23 is a hormone controlling renal phosphate and vitamin D metabolism. Here, we studied the role of ET-1 and endothelin receptor B (ETB) for FGF23 production. Fgf23 gene expression was studied in IDG-SW3 bone cells by quantitative RT-PCR. ETB-expressing (etb+/+ ) and rescued ETB-deficient mice (etb-/- ) were studied in metabolic cages. Their serum FGF23, PTH, and 1,25(OH)2 D3 concentrations were determined by ELISA, serum and urinary phosphate and Ca2+ by photometric methods. ET-1 and ETB agonist sarafotoxin 6c suppressed Fgf23 mRNA in IDG-SW3 cells. Serum C-terminal and intact FGF23 as well as bone Fgf23 mRNA levels were significantly higher in etb-/- mice than in etb+/+ mice. Renal phosphate excretion was significantly higher in etb-/- mice despite lower phosphate levels. In addition, etb-/- animals exhibited calciuria and a significantly higher serum 1,25(OH)2 D3 concentration compared to etb+/+ mice. In conclusion, ETB-dependent ET-1 signaling is a potent suppressor of FGF23 formation. This effect is likely to be of clinical relevance given the use of endothelin receptor antagonists in various diseases.

In people with pulmonary arterial hypertension, is there randomized controlled trial evidence to support the use of endothelin receptor antagonists?

In people with pulmonary arterial hypertension, is there randomized controlled trial evidence to support the use of endothelin receptor antagonists?

Volume Management in Pulmonary Arterial Hypertension Patients: An Expert Pulmonary Hypertension Clinician Perspective.

Fluid volume management in patients with pulmonary arterial hypertension (PAH) is essential in preventing right ventricular failure. Volume overload may be caused by disease progression, indiscretion of dietary sodium and fluid intake, or medication side effects, and is a frequent complication in patients with PAH. Healthcare professionals (HCPs) who care for patients with PAH have a key role in monitoring, preventing, and managing volume overload. Volume management techniques in patients with PAH include managing diuretic use and electrolyte imbalances, and monitoring fluid retention that can occur from the use of endothelin receptor antagonists or calcium channel blockers. Healthcare providers can create volume management protocols as well as patient educational materials. Patients should be educated to self-monitor their daily weights, incorporate dietary restrictions, and recognize symptoms associated with volume overload. Tools to help HCPs with volume management in patients with PAH are provided in this article.Funding Actelion Pharmaceuticals US, Inc.

Sex differences in hemodynamic responses and long-term survival to optimal medical therapy in patients with pulmonary arterial hypertension

It is widely known that the incidence of pulmonary arterial hypertension (PAH) is higher in female, whereas prognosis is poorer in male patients. However, sex differences in hemodynamic response to and long-term prognosis with PAH-targeted treatment in the modern era remain to be fully elucidated. We examined the long-term prognosis of 129 consecutive PAH patients (34 males and 95 females) diagnosed in our hospital from April 1999 to October 2014, and assessed hemodynamic changes in response to PAH-targeted therapy. Female patients had better 5-year survival compared with male patients (74.0 vs. 53.4%, P = 0.003); however, higher age quartiles in females were associated with poor outcome. Follow-up examination after medical treatment showed significant decreases in mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), and pulmonary arterial capacitance (PAC) in both sexes (both P < 0.05), whereas only females had a significant improvement in right ventricular end-diastolic pressure (RVEDP), right atrial pressure (RAP), cardiac index, and mixed venous oxygen saturation (SvO2) (all P < 0.05). Baseline age significantly correlated with the hemodynamic changes only in female patients; particularly, there were significant sex interactions in RVEDP and RAP (both P < 0.10). The multivariable analysis showed that SvO2 at baseline and mPAP and SvO2 at follow-up were significant prognostic factors in males, whereas the changes in mPAP, PVR, and PAC and use of endothelin-receptor antagonist in females. These results indicate that female PAH patients have better long-term prognosis than males, for which better improvements of right ventricular functions and hemodynamics may be involved.

Atrasentan for the treatment of diabetic nephropathy

ABSTRACTIntroduction: Endothelin-1 (ET-1) is the most potent vasoconstrictor, and is involved in the renal regulation of salt and water homeostasis. When produced in excess in the kidney, ET-1 promotes proteinuria and tubulointerstitial injury. There is great interest in the clinical use of endothelin receptor antagonists (ERAs) in chronic kidney disease (CKD), mainly in diabetic nephropathy (DN).Areas covered: Physiopathological actions of ET-1 on the kidney. Both dual ETAR/ETBR (bosentan) or ETAR specific endothelin antagonists (avosentan and atrasentan, among others), which have progressed to early clinical development, with particular emphasis on atrasentan.Expert opinion: Different phase I and II clinical trials with ERAs in DN, mostly with atrasentan, have shown that these drugs have a marked anti-proteinuric effect on residual proteinuria when administered as add-on therapy in addition to ACEi or ARAII treatment. In the past few years, a series of randomized controlled trials investigating new approaches to DN have provided negative or inconclusive data, or even were terminated due to safety concerns or lack of efficacy. Therefore, we eagerly but cautiously await the results of the ongoing SONAR trial with atrasentan in more than 4,000 patients including assessment of renal and cardiovascular hard-end points (estimated primary completion date, July 2018).

Survival of Japanese Patients With Idiopathic/Heritable Pulmonary Arterial Hypertension

Idiopathic/heritable pulmonary arterial hypertension has a poor prognosis despite the available therapeutic options. Survival of Japanese patients with this disease entity has not been reported in the multicenter setting. A retrospective study of 141 patients with idiopathic/heritable pulmonary arterial hypertension treated at 3 pulmonary hypertension centers in Japan from 1992 to 2012 investigated survival and determinants of survival. Mean survival time from treatment initiation was 14.7 ± 0.8years (95% confidence interval, 13.1 to 16.3years) and the 1-, 3-, 5-, and 10-year survival rates were 97.9%, 92.1%, 85.8%, and 69.5%, respectively. Patients showed significant improvement in exercise capacity and hemodynamics after treatment. Patients with 6-minute walk distance >372m, mean pulmonary arterial pressure ≤46mm Hg, and cardiac index >2.5L/min/m2 at follow-up had a significantly better prognosis. Most patients (99.2%) were receiving pulmonary hypertension-targeted drugs at follow-up. Use of endothelin receptor antagonists and intravenous epoprostenol were related to survival in the univariate analysis. Among thepatients who were on intravenous epoprostenol therapy, those with endothelin receptorantagonists had a significantly better prognosis, whereas patients on warfarin hada significantly worse prognosis. In conclusion, survival of Japanese patients with idiopathic/heritable pulmonary arterial hypertension in this study was good, showing improvement in hemodynamic parameters supported by pulmonary hypertension-targeted drugs.

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.

Rationale and Design of Randomized Clinical Trial for the Assessment of Macitentan Efficiency as Coadjuvant Treatment to Open and Endovascular Revascularization in Critical Limb Ischemia

INTRODUCTIONCritical limb ischemia (CLI) is defined by ischemic rest pain, tissue loss, or both, secondary to arterial insufficiency, and its prevalence is increasing mainly as a result of the worldwide high prevalence of diabetes. Currently, there are no available conclusive data on the efficacy of any coadjuvant therapy after revascularization procedure benefiting amputation and patency rates. Macitentan is an orally active dual endothelin (ET) receptor antagonist that may contribute to reduce the amputation rate and improve revascularization patency in CLI.METHODS/DESIGNREVASC is a proposed pilot, open-label, controlled, randomized, single-center clinical double-blind trial to be conducted in Spain on a study population of European patients with CLI, which will compare the clinical outcomes and cost-effectiveness of macitentan coadjuvant treatment after limb revascularization with the standard antiplatelet treatment strategy for severe limb ischemia. Patients are randomized 1:1 to receive macitentan or placebo for 12 weeks. The primary clinical end point will be amputation-free survival rate at 12 months, defined as the time to major (above the ankle) amputation for the index (trial) limb or death from any cause, whichever comes first. Secondary outcomes include overall survival, quality of life, in-hospital mortality and morbidity, repeat interventions, healing of tissue loss, and hemodynamic changes following revascularization. Sample size is estimated as 120 patients. The economic analysis will consist of two components: a “within-study” analysis, which will be based on study end points; and a “model-based” analysis, which will extrapolate and compare costs and effects likely to accrue beyond the study follow-up period.DISCUSSIONThe REVASC trial is designed to be pragmatic and represents current practice of the real-world population management after limb revascularization for CLI due to atherosclerosis. Current evidence does not support any coadjuvant treatment. A new pathway of treatment may be opened with the use of ET receptor antagonists in these patients.

In Memoriam: Wolfgang Kiowski, M.D. (1949–2012) - Pioneer in clinical endothelin research

Wolfgang Kiowski, M.D. (1949–2012) was a German physician-scientist who made exemplary contributions to clinical research in human physiology, heart failure, arterial hypertension, and endothelin science. His academic career took him from Heinz Losse, M.D. at the University of Münster, Germany, to the University of Michigan, U.S.A., to work with Stevo Julius, M.D. In 1979, Kiowski was recruited to the University of Basel in Switzerland and ultimately moved to the Hospital of the University of Zürich in Switzerland. Twenty years ago, Kiowski published a landmark study pioneering the use of endothelin receptor antagonists (ERAs) in patients (Lancet 1995; 346: 732–736), which introduced a new therapeutic principle to human medicine. During his career, he published numerous studies in the area of pathophysiology, clinical pharmacology (particularly calcium channel blockers, ERAs, and PDE5 inhibitors), heart failure, cardiac transplantation, coronary artery disease, and many case reports from his clinical work. Kiowski was an active mentor and trained many young physicians and physician-scientists. He died unexpectedly in Zürich during the planning stages of the Thirteenth International Conference on Endothelin to be held in Tokyo in 2013. This article summarizes Kiowski's achievements, his role as a mentor and as the human being he was. He will be remembered as a role model of an outstanding, curious clinician who was highly successful as a physician, scientist, and teacher, and at the same time managed to enjoy many hobbies and life with his family. Referring to Wolfgang Kiowski, the article closes with a “It can be done!”—message to young physician-scientists by Dr. Stevo Julius.

MACITENTAN: THE EVOLUTION OF THE CLASS ENDOTHELIN RECEPTOR ANTAGONISTS TO IMPROVE EFFICACY AND SAFETY OF PAH TREATMENT

Pulmonary arterial hypertension (PAH) is a severe progressive disease, characterized by advanced remodeling of small pulmonary arteries and arterioles, which ultimately leads to right heart failure and death. Due to discovery of PAH pathophysiological targets, new medications have been developed and implemented into clinical practice. These medications compensate the deficiencies of endogenous prostacyclin and nitric oxide and also block the effects of endothelin-1 (ET-1). The role of the latter in PAH pathophysiology is related to its strong vasoconstrictory properties, as well as to a number of effects responsible for arterial wall remodeling. Clinical use of endothelin receptor antagonists (ERA) started in 2001, with the first agent of the class, bosentan, whose efficacy was demonstrated in a number randomized controlled trials. Macitentan is a novel potent double action oral ERA, developed with the purpose to improve efficacy and safety of PAH treatment through its tissue specificity. The new molecule blocks endothelin receptors type A and B and possesses improved physicochemical properties allowing for improved tissue penetration. Macitentan prevents an increase in pulmonary arterial pressure, right ventricle hypertrophy and improves survival in animal models. The SERAPHIN Study evaluated the effects of macitentan on morbidity/mortality in 742 PAH patients, randomized to macitentan 3 mg or 10 mg daily or placebo. Macitentan 3 mg and 10 mg daily was shown to reduce morbidity and mortality by 30% and 45%, respectively. By 6 month of the follow-up, there was an improvement in 6-minute walking test by + 16.8 m for macitentan 3 mg and +22.0 m for macitentan 10 mg daily. An improvement of the functional class, compared to baseline, was observed by 6 mo in 13% of placebo patients, 20% of macitentan 3 mg daily patients (p=0.04) and in 22% of 10 mg daily patients (0.006). Compared to placebo, macitentan significantly reduced pulmonary vascular resistance and improved cardiac index. It demonstrated a favorable safety profile. US Food and Drug Administration (FDA) approved macitentan (OPSUMIT) 10 mg once daily for the treatment of pulmonary arterial hypertension to delay disease progression.

Endothelin Receptor Antagonists for Aneurysmal Subarachnoid Hemorrhage

Endothelin is considered to be a key mediator of vasospasm after subarachnoid hemorrhage. A meta-analysis of randomized trials on the effectiveness of endothelin receptor antagonists in subarachnoid hemorrhage has been published previously, but since then new major trials have been published. We present the results of a systematic review and meta-analysis update. We searched the Cochrane Library, the Cochrane Central Register of Controlled Trials, and PubMed with the following terms: subarachnoid hemorrhage AND (endothelin receptor antagonist OR clazosentan OR TAK-044 OR bosentan). All randomized, placebo-controlled trials investigating the effect of any endothelin receptor antagonists in patients with subarachnoid hemorrhage were included. Primary outcome was poor functional outcome (defined as death or dependency). Secondary outcomes were vasospasm, cerebral infarction as defined by investigators, and case fatality during follow-up. Data were pooled and effect sizes were expressed as risk ratio (RR) estimates with 95% confidence intervals (CI). We also calculated RR for several common complications. in 5 trials with 2601 patients, endothelin receptor antagonists did not affect functional outcome (RR, 1.06: 95% CI, 0.93-1.22) despite a decreased incidence of angiographic vasospasm (RR, 0.58; 95% CI, 0.48-0.71). No effect was observed on vasospasm-related cerebral infarction (RR, 0.76; 95% CI, 0.53-1.11), any new cerebral infarction (RR, 1.04; 95% CI, 0.91-1.19), or case-fatality (RR, 1.04; 95% CI, 0.78-1.39). Endothelin receptor antagonists increased the risk of lung complications (RR, 1.79; 95% CI, 1.52-2.11), pulmonary edema (RR, 2.12; 95% CI, 1.32-3.39), hypotension (RR, 2.42: 95% CI, 1.78-3.29), and anemia (RR, 1.47; 95% CI, 1.19-1.83). These results argue against the use of endothelin receptor antagonists in patients with subarachnoid hemorrhage.

Endothelin in hypertension

The purpose of this review of the vascular biology of endothelin-1 (ET-1) is the presentation of recent data including the use of endothelin-receptor antagonists for the treatment of hypertension. Recent discoveries regarding the pharmacology of ET-1 in the vascular wall and its effect on signalling transduction and gene expression in vascular smooth muscle cells are reviewed, as well as mechanisms controlling blood pressure in normal conditions and in hypertension, discovered using genetically modified models. Finally, studies of endothelin antagonists for treatment of hypertension will be summarized. Pharmacological studies demonstrate that calcitonin gene-related peptide is a physiological antagonist of ET-1 that terminates the long-lasting contraction induced by ET-1. ET-1-induced rise in [Ca]i involves the newly described stromal-interaction molecule-1/orai1 pathway to increase store-operated calcium entry. Sensitization of contractile proteins to calcium during ET-1-induced contraction of vascular smooth muscle cells includes activation of p63Rho guanine nucleotide exchange factor and increase in O-GlcNAcylation, a form of posttranslational modification. Genetically modified mice have demonstrated that endothelial ET-1 is involved in the regulation of normal blood pressure and development of vascular disease. Gene expression induced by endothelial overexpression of ET-1 in mice demonstrated upregulation of lipid metabolism, inflammatory and signal transduction genes. Crossing these mice with apoE mice was associated with acceleration of atherosclerosis on a high-fat diet and blood pressure elevation. Finally, the DORADO clinical trial has demonstrated that the ETA-receptor antagonist darusentan is able to decrease the blood pressure of patients with refractory hypertension.

Dual therapy in IPAH and SSc-PAH. A qualitative systematic review

Use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 (PDE-5) inhibitors and prostaglandin analogues has resulted in improved outcomes in idiopathic pulmonary arterial hypertension (IPAH) and systemic sclerosis-associated PAH (SSc-PAH) patients. However, patients often deteriorate on monotherapy. The objective of this study is to evaluate the effect of dual therapy on outcomes in IPAH and SSc-PAH. A systematic review of MEDLINE (1950-2011), EMBASE (1980-2011) and CINAHL (inception-2011) was conducted to identify studies that evaluated the effect of any dual combination of ERA, PDE-5 inhibitors or prostaglandin analogues on 6-min walk distance (6MWD), functional class (FC), haemodynamics, quality-of-life (QoL) or time-to-clinical-worsening in IPAH or SSc-PAH. A standardized form was used to abstract design, sample size, aetiology, outcome and treatment effect. Twenty-six observational studies and 6 randomized trials were identified. Using combination PDE-5 inhibitor and prostaglandin analogues, 6/7 studies reported improvement in 6MWD, 6/8 studies reported improvement in FC, 6/6 studies reported improvement in haemodynamics and 1 trial demonstrated improvement in QoL and time-to-clinical-worsening. Using combination ERA and prostaglandin analogues, 4/6 studies and 1 trial reported improvement in 6MWD, 3/3 studies and 1 trial reported improvement in FC, 4/5 studies and 1 trial reported improvement in PAP. Using combination ERA and PDE-5 inhibitor, 4/7 studies reported an improvement in 6MWD, and 2/6 report improvement in FC. The evidence suggests a beneficial effect of dual therapy in IPAH and SSc-PAH, particularly those who are deteriorating on monotherapy. Research should focus on subsets of patients to identify the optimal timing and combination of dual therapy.