A 24-Year-Old Woman With Dyspnea, Chest Pain, and Dry Cough.

CASE PRESENTATION: A 24-year-old woman, a baby-sitter with no known comorbidities, presented to the outpatient department with complaints of modified Medical Research Council grade IV breathlessness for 3 months, chest pain, and dry cough for 2 weeks. There was no known disease history, including respiratory, flu-like illness, or connective tissue disorder. There was no use of chemotherapeutic, oral contraceptive drugs, exposure to toxic substances, or smoking. A review of systems was negative for fever, arthralgia, myalgia, Raynaud phenomenon, skin thickening, rash, or leg swelling. The patient had no family history suggestive of a genetic syndrome.

Modulation by antenatal therapies of cardiovascular and renal programming in male and female offspring of preeclamptic rats.

Morbidity and mortality risks are enhanced in preeclamptic (PE) mothers and their offspring. Here, we asked if sexual dimorphism exists in (i) cardiovascular and renal damage evolved in offspring of PE mothers, and (ii) offspring responsiveness to antenatal therapies. PE was induced by administering NG-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg/day, oral gavage) to pregnant rats for 7 days starting from gestational day 14. Three therapies were co-administered orally with L-NAME, atrasentan (endothelin ETA receptor antagonist), terutroban (thromboxane A2 receptor antagonist, TXA2), or α-methyldopa (α-MD, central sympatholytic drug). Cardiovascular and renal profiles were assessed in 3-month-old offspring. Compared with offspring of non-PE rats, PE offspring exhibited elevated systolic blood pressure and proteinuria and reduced heart rate and creatinine clearance (CrCl). Apart from a greater bradycardia in male offspring, similar PE effects were noted in male and female offspring. While terutroban, atrasentan, or α-MD partially and similarly blunted the PE-evoked changes in CrCl and proteinuria, terutroban was the only drug that virtually abolished PE hypertension. Rises in cardiorenal inflammatory (tumor necrosis factor alpha, TNFα) and oxidative (isoprostane) markers were mostly and equally eliminated by all therapies in the two sexes, except for a greater dampening action of atrasentan, compared with α-MD, on tissue TNFα in female offspring only. Histopathologically, antenatal terutroban or atrasentan was more effective than α-MD in rectifying cardiac structural damage, myofiber separation, and cytoplasmic alterations, in PE offspring. The repair by antenatal terutroban or atrasentan of cardiovascular and renal anomalies in PE offspring is mostly sex-independent and surpasses the protection offered by α-MD, the conventional PE therapy.

Inhibition of endothelin A receptor by a novel, selective receptor antagonist enhances morphine-induced analgesia: Possible functional interaction of dimerized endothelin A and µ-opioid receptors.

BACKGROUND: The misuse of opioids has led to an epidemic in recent times. The endothelin A receptor (ETAR) has recently attracted attention as a novel therapeutic target to enhance opioid analgesia. We hypothesized that endothelin A receptors may affect pain mechanisms by heterodimerization with µ opioid receptors. We examined the mechanisms of ETAR-mediated pain and the potential therapeutic effects of an ETAR antagonist, Compound-E, as an agent for analgesia. METHODS: Real-time in vitro effect of Compound-E on morphine response was assessed in HEK293 cells expressing both endothelin A and µ opioid receptors through CellKey™ and cADDis cAMP assays. Endothelin A/µ opioid receptor dimerization was assessed by immunoprecipitation and live cell imaging. The in vivo effect of Compound-E was evaluated using a morphine analgesia mouse model that observed escape response behavior, body temperature, and locomotor activity. RESULTS: In CellKey™ and cAMP assays, pretreatment of cells with endothelin-1 attenuated morphine-induced responses. These responses were improved by Compound-E, but not by BQ-123 nor by bosentan, an ETAR and endothelin B receptor antagonist. Dimerization of ETARs and µ opioid receptors was confirmed by Western blot and total internal reflection fluorescence microscopy in live cells. In vivo, Compound-E potentiated and prolonged the analgesic effects of morphine, enhanced hypothermia, and increased locomotor activity compared to morphine alone. CONCLUSION: The results suggest that attenuation by endothelin-1 of morphine analgesia may be caused by dimerization of Endothelin A/µ opioid receptors. The novel ETAR antagonist Compound-E could be an effective adjunct to reduce opioid use.

Association Between Vomiting and QT Hysteresis: Data from a TQT Study with the Endothelin A Receptor Antagonist Clazosentan.

This study investigated the potential QT liability of the selective endothelin-1 A receptor antagonist clazosentan at a therapeutic (20 mg/h) and supratherapeutic (60 mg/h) intravenous (i.v.) dose. A randomized, placebo- and moxifloxacin-controlled, double-blind, 3-period, crossover study was conducted in 36 healthy subjects receiving clazosentan (20 mg/h followed by 60 mg/h i.v. for 3 h each), placebo (i.v. for 6 h), and moxifloxacin (single oral dose of 400 mg concomitantly with placebo i.v. for 6 h). At least three replicate ECGs were extracted from Holter recordings at predefined time points from 1 h pre-dose to 24 h after end of infusion. Pharmacokinetic blood sampling was performed for concentration/QT analysis (primary endpoint). For moxifloxacin, the lower bound of the 90% confidence interval (CI) of baseline- and placebo-corrected QTcF (ΔΔQTcF) was > 5 ms at its maximum plasma concentration together with a positive slope of the concentration/QT regression line demonstrating assay sensitivity. For clazosentan, time of peak exposure preceded maximum ΔΔQTcF by 4 h indicating delayed QT-prolonging effects leading to invalidity of the concentration/QT analysis. The secondary by-time-point analysis revealed QT liability of clazosentan (i.e., upper bound of 90% CI ∆∆QTcF > 10 ms). Delayed QT prolongation (i.e., hysteresis) was predominantly observed in subjects with nausea and vomiting, potentially caused by vagal reaction and/or decreases in potassium concentration. By contrast, there was no association with other adverse events, food intake, or concomitant medication. In conclusion, clazosentan at therapeutic and supratherapeutic doses has QT liability with hysteresis effects being associated with nausea and vomiting.

Clinical efficacy and safety of switch from bosentan to macitentan in children and young adults with pulmonary arterial hypertension: extended study results.

BACKGROUND: Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term study. AIM: We have recently reported that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension in a 24-week prospective study and well tolerated without adverse events. We now aimed to evaluate clinical efficacy, safety of switch in a larger patient population, in a 24-month prospective study. METHODS: This is a single-institution, 24-month prospective study. Patients ≥12 years with idiopathic/heritable, pulmonary arterial hypertension, or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan treatment were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors/inhaled prostanoids was allowed. Outcome measures included change from baseline to 24 months, in the 6-minute walk distance, functional class, oxygen saturation at rest/after walk distance test, and natriuretic peptide levels. Safety end points included adverse events, laboratory abnormalities. RESULTS: Twenty-seven patients (19 adults/8 children, mean age: 21.1 ± 6.3 years (12-36), weight: 53.1 ± 15.7 kgs (26-87)) were included. Mean duration of macitentan treatment: 22.3 ± 3.9 months (9-24). Six-minute walk distance significantly improved from baseline (mean: 458 ± 79 m (300-620)) at 6 months (mean: 501 ± 73 m (325-616) + 43 m) (p < 0.05), at 12 months (mean: 514 ± 82 m (330-626) + 56 m) (p < 0.05), and at 24 months (mean: 532 ± 85 m (330-682) + 74 m) (p < 0.05). We observed a significant improvement during the first 6 months but no incremental improvement after 6 months (p > 0.05). Macitentan did not significantly change functional class, oxygen saturation, and natriuretic levels (p > 0.05). None of the patients had anaemia, hepatotoxicity, and peripheral edema. CONCLUSIONS: Our study is the first study which showed that switch from bosentan to macitentan improved exercise capacity in children and young adults with pulmonary arterial hypertension significantly in the first 6 months and compared to baseline in 24 months and well tolerated without adverse events.

Antioxidant effect of endothelin-1 receptor antagonist protects the rat kidney against chronic injury induced by hypertension and hyperglycemia.

Hypertension and Diabetes mellitus are the two main causes of chronic kidney disease that culminate in the final stage of kidney disease. Since these two risk factors are common and can overlap, new approaches to prevent or treat them are needed. Macitentan (MAC) is a new non-selective antagonist of the endothelin-1 (ET-1) receptor. This study aimed to evaluate the effect of chronic blockade of ET-1 receptor with MAC on the alteration of renal function observed in hypertensive and hyperglycemic animals. Genetically hypertensive rats were divided into control hypertensive (HT-CTL) group, hypertensive and hyperglycemic (HT+DIAB) group, and hypertensive and hyperglycemic group that received 25 mg/kg macitentan (HT-DIAB+MAC25) via gavage for 60 days. Kidney function and parameters associated with oxidative and nitrosative stress were evaluated. Immunohistochemistry for neutrophil gelatinase-associated lipocalin (NGAL), ET-1, and catalase in the renal cortex was performed. The HT+DIAB group showed a decrease in kidney function and an increase in NGAL expression in the renal cortex, as well as an increase in oxidative stress. MAC treatment was associated with attenuated ET-1 and NGAL production and increases in antioxidant defense (catalase expression) and nitric oxide production. In addition, MAC prevented an increase in oxidant injury (as measured by urinary hydroperoxide and lipid peroxidation), thus improving renal function. Our results suggest that the antioxidant effect of the ET-1 receptor antagonist MAC is involved in the improvement of kidney function observed in hypertensive and hyperglycemic rats.

Endothelin receptor-A mediates degradation of the glomerular endothelial surface layer via pathologic crosstalk between activated podocytes and glomerular endothelial cells.

Emerging evidence of crosstalk between glomerular cells in pathological settings provides opportunities for novel therapeutic discovery. Here we investigated underlying mechanisms of early events leading to filtration barrier defects of podocyte and glomerular endothelial cell crosstalk in the mouse models of primary podocytopathy (podocyte specific transforming growth factor-ß receptor 1 signaling activation) or Adriamycin nephropathy. We found that glomerular endothelial surface layer degradation and albuminuria preceded podocyte foot process effacement. These abnormalities were prevented by endothelin receptor-A antagonism and mitochondrial reactive oxygen species scavenging. Additional studies confirmed increased heparanase and hyaluronoglucosaminidase gene expression in glomerular endothelial cells in response to podocyte-released factors and to endothelin-1. Atomic force microscopy measurements showed a significant reduction in the endothelial surface layer by endothelin-1 and podocyte-released factors, which could be prevented by endothelin receptor-A but not endothelin receptor-B antagonism. Thus, our studies provide evidence of early crosstalk between activated podocytes and glomerular endothelial cells resulting in loss of endothelial surface layer, glomerular endothelial cell injury and albuminuria. Hence, activation of endothelin-1-endothelin receptor-A and mitochondrial reactive oxygen species contribute to the pathogenesis of primary podocytopathies in experimental focal segmental glomerulosclerosis.

Intracerebroventricular endothelin receptor-A blockade in rats decreases phase-II ventricular tachyarrhythmias during acute myocardial infarction.

Endothelin alters central sympathetic responses, but the resultant effects on arrhythmogenesis are unknown. We examined ventricular tachyarrhythmias after endothelin receptor-A blockade in the brain of Wistar rats with acute myocardial infarction. For this aim, BQ-123 (n=6) or phosphate-buffered saline (n=6) were injected intracerebroventricularly. After 10 min, the left coronary artery was ligated, followed by implantation of telemetry transmitters. Electrocardiography and voluntary activity (as a surrogate of acute left ventricular failure) were continuously monitored for 24 h. Infarct-size was similar in the two groups. There were fewer episodes of ventricular tachyarrhythmias of shorter average duration in treated rats, leading to markedly shorter total duration (12.3+/-8.9 s), when compared to controls (546.2+/-130.3 s). Voluntary activity increased in treated rats during the last hours of recording, but bradyarrhythmic episodes were comparable between the two groups. Endothelin receptor-A blockade in the brain of rats decreases the incidence of ventricular tachyarrhythmias post-ligation, without affecting bradyarrhythmic episodes. These findings call for further research on the pathophysiologic role of endothelin during acute myocardial infarction.

Intracellular iron deficiency in pulmonary arterial smooth muscle cells induces pulmonary arterial hypertension in mice.

Iron deficiency augments hypoxic pulmonary arterial pressure in healthy individuals and exacerbates pulmonary arterial hypertension (PAH) in patients, even without anemia. Conversely, iron supplementation has been shown to be beneficial in both settings. The mechanisms underlying the effects of iron availability are not known, due to lack of understanding of how cells of the pulmonary vasculature respond to changes in iron levels. The iron export protein ferroportin (FPN) and its antagonist peptide hepcidin control systemic iron levels by regulating release from the gut and spleen, the sites of absorption and recycling, respectively. We found FPN to be present in pulmonary arterial smooth muscle cells (PASMCs) and regulated by hepcidin cell autonomously. To interrogate the importance of this regulation, we generated mice with smooth muscle-specific knock in of the hepcidin-resistant isoform fpn C326Y. While retaining normal systemic iron levels, this model developed PAH and right heart failure as a consequence of intracellular iron deficiency and increased expression of the vasoconstrictor endothelin-1 (ET-1) within PASMCs. PAH was prevented and reversed by i.v. iron and by the ET receptor antagonist BQ-123. The regulation of ET-1 by iron was also demonstrated in healthy humans exposed to hypoxia and in PASMCs from PAH patients with mutations in bone morphogenetic protein receptor type II. Such mutations were further associated with dysregulation of the HAMP/FPN axis in PASMCs. This study presents evidence that intracellular iron deficiency specifically within PASMCs alters pulmonary vascular function. It offers a mechanistic underpinning for the known effects of iron availability in humans.

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

BACKGROUND: 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. METHODS: 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. FINDINGS: 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). INTERPRETATION: 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. FUNDING: AbbVie.

The Endothelin-A Receptor Antagonist Zibotentan Induces Damage to the Nasal Olfactory Epithelium Possibly Mediated in Part through Type 2 Innate Lymphoid Cells.

Zibotentan, an endothelin-A receptor antagonist, has been used in the treatment of various cardiovascular disorders and neoplasia. Castrated athymic nude mice receiving zibotentan for a preclinical xenograft efficacy study experienced weight loss, gastrointestinal bloat, and the presence of an audible respiratory click. Human side effects have been reported in the nasal cavity, so we hypothesized that the nasal cavity is a target for toxicity in mice receiving zibotentan. Lesions in the nasal cavity predominantly targeted olfactory epithelium in treated mice and were more pronounced in castrated animals. Minimal lesions were present in vehicle control animals, which suggested possible gavage-related reflux injury. The incidence, distribution, and morphology of lesions suggested direct exposure to the nasal mucosa and a possible systemic effect targeting the olfactory epithelium, driven by a type 2 immune response, with group 2 innate lymphoid cell involvement. Severe nasal lesions may have resulted in recurrent upper airway obstruction, leading to aerophagia and associated clinical morbidity. These data show the nasal cavity is a target of zibotentan when given by gavage in athymic nude mice, and such unanticipated and off-target effects could impact interpretation of research results and animal health in preclinical studies.

DUET: A Phase 2 Study Evaluating the Efficacy and Safety of Sparsentan in Patients with FSGS.

BACKGROUND: We evaluated and compared the effects of sparsentan, a dual endothelin type A (ETA) and angiotensin II type 1 receptor antagonist, with those of the angiotensin II type 1 receptor antagonist irbesartan in patients with primary FSGS. METHODS: In this phase 2, randomized, double-blind, active-control Efficacy and Safety of Sparsentan (RE-021), a Dual Endothelin Receptor and Angiotensin Receptor Blocker, in Patients with Focal Segmental Glomerulosclerosis (FSGS): A Randomized, Double-blind, Active-Control, Dose-Escalation Study (DUET), patients aged 8-75 years with biopsy-proven FSGS, eGFR>30 ml/min per 1.73 m2, and urinary protein-to-creatinine ratio (UP/C) ≥1.0 g/g received sparsentan (200, 400, or 800 mg/d) or irbesartan (300 mg/d) for 8 weeks, followed by open-label sparsentan only. End points at week 8 were reduction from baseline in UP/C (primary) and proportion of patients achieving FSGS partial remission end point (FPRE) (UP/C: ≤1.5 g/g and >40% reduction [secondary]). RESULTS: Of 109 patients randomized, 96 received study drugs and had baseline and week 8 UP/C measurements. Sparsentan-treated patients had greater reductions in UP/C than irbesartan-treated patients did when all doses (45% versus 19%; P=0.006) or the 400 and 800 mg doses (47% versus 19%; P=0.01) were pooled for analysis. The FSGS partial remission end point was achieved in 28% of sparsentan-treated and 9% of irbesartan-treated patients (P=0.04). After 8 weeks of treatment, BP was reduced with sparsentan but not irbesartan, and eGFR was stable with both treatments. Overall, the incidence of adverse events was similar between groups. Hypotension and edema were more common among sparsentan-treated patients but did not result in study withdrawals. CONCLUSIONS: Patients with FSGS achieved significantly greater reductions in proteinuria after 8 weeks of sparsentan versus irbesartan. Sparsentan was safe and well tolerated.

Endothelin and diabetic complications: a brain-centric view.

The global epidemic of diabetes is of significant concern. Diabetes associated vascular disease signifies the principal cause of morbidity and mortality in diabetic patients. It is also the most rapidly increasing risk factor for cognitive impairment, a silent disease that causes loss of creativity, productivity, and quality of life. Small vessel disease in the cerebral vasculature plays a major role in the pathogenesis of cognitive impairment in diabetes. Endothelin system, including endothelin-1 (ET-1) and the receptors (ET(A) and ET(B)), is a likely candidate that may be involved in many aspects of the diabetes cerebrovascular disease. In this review, we took a brain-centric approach and discussed the role of the ET system in cerebrovascular and cognitive dysfunction in diabetes.

Antibodies targeting human endothelin-1 receptors reveal different conformational states in cancer cells.

The endothelin axis (endothelins and their receptors) is strongly involved in physiological and pathological processes. ET-1 plays a crucial role in particular in tumor diseases. Endothelin-1 receptors (ET(A) and ET(B)) are deregulated and overexpressed in several tumors such as melanoma and glioma. We studied the binding of 24 monoclonal antibodies directed against human ET(B) receptors (hET(B)) to different melanoma cell lines. Few of these mAbs bound to all the melanoma cell lines. One of them, rendomab B49, bound to ET(B) receptors expressed at the surface of human glioma stem cells. More recently, we produced new antibodies directed against human ET(A) receptor (hET(A)). Several antibodies have been isolated and have been screened on different tumoral cells lines. As for the mAbs directed against the hET(B) receptor only some of new antibodies directed against ET(A) receptor are capable to bind the human tumoral cell lines. Rendomab A63 directed against hET(A) is one of them. We report the specificity and binding properties of these mAbs and consider their potential use in diagnosis by an in vivo imaging approach.

Systemic scleroderma-related interstitial pneumonia associated with borderline pulmonary arterial hypertension.

A 65-year-old woman with a 35-year history of limited cutaneous systemic scleroderma was admitted to our hospital complaining of a 3-month history of progressive dyspnoea on exertion. High-resolution CT images of the chest revealed diffuse reticular opacities and traction bronchiectasis predominantly in the bilateral lower lobes of the lung. Specimens obtained during video-assisted thoracic surgery were consistent with fibrocellular non-specific interstitial pneumonia and accompanied by accumulation of lymph follicles within areas of fibrosis. Although the patient received combination therapy with prednisolone and intravenous cyclophosphamide at a dosage of 500 mg/m2 monthly for 5 months, her clinical condition deteriorated gradually. In addition, right heart catheterisation revealed borderline pulmonary arterial hypertension with mean pulmonary artery pressure of 24 mm Hg. Therefore, we initiated a combination therapy of an antifibrotic agent, pirfenidone for 12 months, and the dual endothelin receptor antagonist, macitentan, with prednisolone. As a result, her clinical condition improved dramatically.

Determining the optimal dose of atrasentan by evaluating the exposure-response relationships of albuminuria and bodyweight.

This study aimed to identify the optimal dose of the endothelin-1 receptor antagonist atrasentan with maximal albuminuria reduction and minimal signs of sodium retention, as manifested by increase in bodyweight. Data from the RADAR-JAPAN studies were used, evaluating the effect of 0.75 or 1.25 mg/d of atrasentan in 161 patients with type 2 diabetes and kidney disease. Individual pharmacokinetic parameters were estimated using a population pharmacokinetic approach. Subsequently, changes in the urinary albumin-to-creatinine ratio (UACR) and bodyweight from baseline after 2 weeks' exposure were modelled as a function of the pharmacokinetic parameters. The 0.75 and 1.25 mg doses showed a mean UACR reduction of 34.0% and 40.1%, whereas mean bodyweight increased by 0.9 and 1.1 kg, respectively. A large variation between individuals was observed in the UACR and bodyweight responses. Individual pharmacokinetic parameters correlated significantly with both individual UACR and bodyweight responses (P < .01). The individual response curves for UACR and bodyweight crossed at approximately the mean trough concentration of 0.75 mg atrasentan, indicating that 0.75 mg/d of atrasentan is the optimal dose for kidney protection with maximal efficacy (albuminuria reduction) and safety (minimal sodium retention).

Modeling of pharmacokinetics, efficacy, and hemodynamic effects of macitentan in patients with pulmonary arterial hypertension.

BACKGROUND: Macitentan is the first endothelin receptor antagonist with demonstrated efficacy on morbidity and mortality in pulmonary arterial hypertension (PAH) in the pivotal study SERAPHIN. METHODS: The pharmacokinetics (PK) of macitentan and its active metabolite, ACT-132577, were characterized in a population model. Efficacy and hemodynamics (pharmacodynamics, PD) were related to PK based on PK/PD modeling. RESULTS: Sex, age, and body weight influenced the PK to a statistically significant extent. Model-based simulations showed that these variables are clinically not relevant. Concomitant use of PAH medication (PDE-5 inhibitors) did not influence macitentan trough concentration to a relevant extent. Efficacy and hemodynamics showed clear differences from placebo for macitentan concentrations on 3 and 10 mg with consistent superior effects for 10 mg. After 6 months, PAH patients showed model-predicted 6-min walk distance (6-MWD) improvements of 1.0 m on placebo compared to 29.8 and 34.1 m on 3 and 10 mg of macitentan, respectively. Higher macitentan concentrations were associated with reductions in pulmonary vascular resistance (PVR), mean right atrial and pulmonary arterial pressure, and total pulmonary resistance (TPR) and increases in cardiac index (CI) and mixed venous oxygen saturation. Statistical significance was determined for PVR, TPR, and CI but not for 6-MWD. In addition, PVR showed more pronounced differences between active treatment and placebo than 6-MWD. CONCLUSIONS: Modeling identified statistically significant inter-patient differences; simulations to assess the magnitude of the effects permitted clinical judgment. The same approach will allow for extrapolation to children. Hemodynamic markers might be better markers of treatment effects than 6-MWD. TRIAL REGISTRATION: The SERAPHIN study and its open-label extension are registered with ClinicalTrials.gov with identifiers NCT00660179 (https://www.clinicaltrials.gov/ct2/show/NCT00660179) and NCT00667823 (https://clinicaltrials.gov/ct2/show/NCT00667823) and with EudraCT with identifiers 2007-002440-14 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-002440-14) and 2007-003694-27 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-003694-27).

Different Doses of Clazosentan for Aneurismal Subarachnoid Hemorrhage: A Meta-Analysis of Randomized Controlled Trials.

Clazosentan therapy has been found to be effective in reducing the incidence of vasospasm after aneurismal subarachnoid hemorrhage (aSAH). The objective of this meta-analysis was to determine whether different doses of clazosentan treatment significantly reduced the incidence of delayed ischemic neurological deficits (DINDs) and new cerebral infarction (NCI). We systematically searched PubMed, Embase, Cochrane library and Medline from inception until October, 2015. All randomized controlled trials related to the functions of clazosentan in aSAH were included. Analyses were performed following the method guideline of Cochrane Back Review Group. Four randomized placebo-controlled trials met eligibility criteria and enrolled a total of 2159 patients. The meta-analysis demonstrated a significant decrease in the incidence of DINDs (relative risk, 0.49 and 95% CI, 0.33-0.73) and NCI (relative risk, 0.42 and 95% CI, 0.25-0.71) in patients treated with a high dose of clazosentan (15 mg/h) after aSAH. In addition, a high dose of clazosentan (15 mg/h) had no more effect on the incidence of adverse events than that of a low dose (1-5 mg/h). The results of the present meta-analysis show that a high dose of clazosentan significantly reduced the incidence of the vasospasm-related DINDs and NCI. Further study is required to fully understand the potential usefulness of clazosentan in patients with aSAH.

Clinical efficacy and safety of switch from bosentan to macitentan in children and young adults with pulmonary arterial hypertension.

BACKGROUND: Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term event-driven study. Aim Few studies compared the clinical efficacy and safety of switch from bosentan to macitentan only in adult patients with pulmonary arterial hypertension. We aimed to evaluate the clinical efficacy and safety of switch from bosentan to macitentan in children and young adults. METHODS: This is a single-institution, 24-week prospective study. Patients ⩾12 years of age with idiopathic/heritable pulmonary arterial hypertension or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan therapy were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors and inhaled prostanoids was allowed. Outcome measures included change from baseline to week 24, in the 6-minute walk distance, functional class, oxygen saturation at rest/after 6-minute walk distance test, systolic pulmonary artery pressure estimated by echocardiography, and brain natriuretic peptide levels. Safety end points included adverse events laboratory abnormalities. RESULTS: A total of 13 patients - 5 male and 8 female - completed the study. The mean age was 20.3±6.5 years (12-35) and weight was 54.0±14.5 kg (27-75). Five patients were ⩽18 years of age. Macitentan improved 6-minute walk distance from baseline (mean: 466±35 m (300-590)), at 12 weeks (mean: 494±78 m (325-590), +28 m) (p0.05). None of the patients had anaemia, hepatotoxicity, and peripheral oedema. CONCLUSIONS: Our study is the first study that showed that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension and is well tolerated without any adverse events.