Endothelin receptor antagonists for pulmonary arterial hypertension

Endothelin receptor antagonists for pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension is a devastating disease that leads to right heart failure and premature death. Endothelin receptor antagonists have shown efficacy in the treatment of pulmonary arterial hypertension.

OBJECTIVES

To evaluate the efficacy of endothelin receptor antagonists (ERAs) in pulmonary arterial hypertension.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and the reference sections of retrieved articles. The searches are current as of 4 November 2020.

SELECTION CRITERIA

We included randomised trials and quasi-randomised trials involving participants with pulmonary arterial hypertension.

DATA COLLECTION AND ANALYSIS

Two of five review authors selected studies, extracted data and assessed study quality according to established criteria. We used standard methods expected by Cochrane. The primary outcomes were exercise capacity (six-minute walk distance, 6MWD), World Health Organization (WHO) or New York Heart Association (NYHA) functional class, Borg dyspnoea scores and dyspnoea-fatigue ratings, and mortality.

MAIN RESULTS

We included 17 randomised controlled trials involving a total of 3322 participants. Most trials were of relatively short duration (12 weeks to six months). Sixteen trials were placebo-controlled, and of these nine investigated a non-selective ERA and seven a selective ERA.   We evaluated two comparisons in the review: ERA versus placebo and ERA versus phosphodiesterase type 5 (PDE5) inhibitor. The abstract focuses on the placebo-controlled trials only and presents the pooled results of selective and non-selective ERAs. After treatment, participants receiving ERAs could probably walk on average 25.06 m (95% confidence interval (CI) 17.13 to 32.99 m; 2739 participants; 14 studies; I² = 34%, moderate-certainty evidence) further than those receiving placebo in a 6MWD. Endothelin receptor antagonists probably improved more participants' WHO functional class (odds ratio (OR) 1.41, 95% CI 1.16 to 1.70; participants = 3060; studies = 15; I² = 5%, moderate-certainty evidence) and probably lowered the odds of functional class deterioration (OR 0.43, 95% CI 0.26 to 0.72; participants = 2347; studies = 13; I² = 40%, moderate-certainty evidence) compared with placebo. There may be a reduction in mortality with ERAs (OR 0.78, 95% CI 0.58, 1.07; 2889 participants; 12 studies; I² = 0%, low-certainty evidence), and pooled data suggest that ERAs probably improve cardiopulmonary haemodynamics and may reduce Borg dyspnoea score in symptomatic patients. Hepatic toxicity was not common, but may be increased by ERA treatment from 37 to 67 (95% CI 34 to 130) per 1000 over 25 weeks of treatment (OR 1.88, 95% CI 0.91 to 3.90; moderate-certainty evidence). Although ERAs were well tolerated in this population, several cases of irreversible liver failure caused by sitaxsentan have been reported, which led the licence holder for sitaxsentan to withdraw the product from all markets worldwide.  As planned, we performed subgroup analyses comparing selective and non-selective ERAs, and with the exception of mean pulmonary artery pressure, did not detect any clear subgroup differences for any outcome.

AUTHORS' CONCLUSIONS

For people with pulmonary arterial hypertension with WHO functional class II and III, endothelin receptor antagonists probably increase exercise capacity, improve WHO functional class, prevent WHO functional class deterioration, result in favourable changes in cardiopulmonary haemodynamic variables compared with placebo. However, they are less effective in reducing dyspnoea and mortality. The efficacy data were strongest in those with idiopathic pulmonary hypertension. The irreversible liver failure caused by sitaxsentan and its withdrawal from global markets emphasise the importance of hepatic monitoring in people treated with ERAs. The question of the effects of ERAs on pulmonary arterial hypertension has now likely been answered.. The combined use of ERAs and phosphodiesterase inhibitors may provide more benefit in pulmonary arterial hypertension; however, this needs to be confirmed in future studies.

Evidence synthesis in pulmonary arterial hypertension: a systematic review and critical appraisal

BACKGROUND

The clinical landscape of pulmonary arterial hypertension (PAH) has evolved in terms of disease definition and classification, trial designs, available therapies and treatment strategies as well as clinical guidelines. This study critically appraises published evidence synthesis studies, i.e. meta-analyses (MA) and network-meta-analyses (NMA), to better understand their quality, validity and discuss the impact of the findings from these studies on current decision-making in PAH.

METHODS

A systematic literature review to identify MA/NMA studies considering approved and available therapies for treatment of PAH was conducted. Embase, Medline and the Cochrane's Database of Systematic Reviews were searched from database inception to April 22, 2020, supplemented by searches in health technology assessment websites. The International Society for Pharmacoeconomics and Outcomes Research (ISPOR) checklist covering six domains (relevance, credibility, analysis, reporting quality and transparency, interpretation and conflict of interest) was selected for appraisal of the included MA/NMA studies.

RESULTS

Fifty-two full publications (36 MAs, 15 NMAs, and 1 MA/NMA) in PAH met the inclusion criteria. The majority of studies were of low quality, with none of the studies being scored as 'strong' across all checklist domains. Key limitations included the lack of a clearly defined, relevant decision problem, shortcomings in assessing and addressing between-study heterogeneity, and an incomplete or misleading interpretation of results.

CONCLUSIONS

This is the first critical appraisal of published MA/NMA studies in PAH, suggesting low quality and validity of published evidence synthesis studies in this therapeutic area. Besides the need for direct treatment comparisons assessed in long-term randomized controlled trials, future efforts in evidence synthesis in PAH should improve analysis quality and scrutiny in order to meaningfully address challenges arising from an evolving therapeutic landscape.

Diagnosis and Management of Pulmonary Hypertension in Patients With CKD

Pulmonary hypertension (PH) is a highly prevalent and important condition in adults with chronic kidney disease (CKD). In this review, we summarize the definition of PH, discuss its pathophysiology and classifications, and describe diagnostic and management strategies in patients with CKD, including those with kidney failure treated by kidney replacement therapy. In the general population, PH is classified into 5 groups based on clinical presentation, pathology, hemodynamics, and management strategies. In this classification system, PH in CKD is placed in a diverse group with unclear or multifactorial mechanisms, although underlying cardiovascular disease may account for most cases. CKD may itself directly incite pulmonary circulatory dysfunction and remodeling through uremic toxins, inflammation, endothelial dysfunction, and altered vasoregulation. Despite several studies describing the higher prevalence of PH in CKD and kidney failure, along with an association with poor outcomes, high-quality evidence is not available for its diagnostic and management strategies in those with CKD. In CKD not requiring kidney replacement therapy, volume management along with treatment of underlying risk factors for PH are critical. In those receiving hemodialysis, options are limited and transition to peritoneal dialysis may be considered if recurrent hypotension precludes optimal volume control.

Clinical outcome and survival in 30 pulmonary hypertension patients with high severity indices and advanced functional class

BACKGROUND

Pulmonary hypertension (PH) is an idiopathic or secondary disorder associated with many systemic illnesses. Long-term survival in PH depends on the severity and functional class. Several new drugs are now available to treat PH, but their impact on clinical outcome and survival are not well established.

OBJECTIVES

Evaluate severity parameters and the impact of current recommended therapy on survival in PH.

DESIGN

Cross-sectional.

SETTINGS

Tertiary care center.

PATIENTS AND METHODS

The study included adult patients who had undergone right heart catheterization since 2012 and were diagnosed with pulmonary hypertension. Survival was recorded after 6 years, at the end of the study. Nine severity variables for PH were assessed including right ventricular size by echocardiogram and pulmonary artery diameter (PA diameter) and the ratio of pulmonary artery diameter to ascending aorta diameter (PA/Ao ratio) by CT.

MAIN OUTCOME MEASURES

Evaluation of severity parameters.

SAMPLE SIZE

30 patients.

RESULTS

Twenty-five patients were positive for 8/9 severity parameters. Eight of 30 (26.6%) patients died. In nonsurvivors, right ventricular size was increased by 25% ( P=.427), pulmonary vascular resistance increased by 29.4% in nonsurvivors ( P=.302), the 6-minute walk distance decreased by 21% ( P=.875), median brain natriuretic peptide increased by 96% ( P=.890), median GGT and alkaline phosphatase were 3 times higher in nonsurvivors ( P=.893 and P=.047, respectively) and PA/Ao was nonsignificantly decreased in nonsurvivors ( P=.373), Survival was decreased by a median of 2.3 years in nonsurvivors.

CONCLUSION

Our study identified a subgroup of PH patients with NYHA functional class III and above with worsening severity indicators who were labeled as a high-risk group. These patients showed continuous deterioration in their clinical status despite escalation of therapy with current guidelines. We recommend these high-risk group patients be referred for early lung transplantation.

LIMITATIONS

Low sample size and only a single center. Needs confirmation with a larger multicenter trial.

CONFLICT OF INTEREST

None.

Dysregulation of the endothelin pathway in lymphangioleiomyomatosis with no direct effect on cell proliferation and migration

LAM is a rare low-grade metastasizing lung neoplasm. Inhibitors of mTOR improve clinical outcome of LAM patients by preventing loss of lung function. Nevertheless, other cell targets may be of interest for drug development. Therefore, we explored the potential role of EDN1 (endothelin) in LAM. We report an increased endothelin blood level in LAM patients as well as EDN1 overexpression and EDN1 receptor downregulation in LAM-derived primary cells and in TSC2^NEG cells mutated in TSC2. We evidenced EDN pathway dysregulation based on EDN1, EDNRA, EDNRB and ARRB1 mRNA expression in LAM-derived primary cells. We showed overexpression of EDN1 and ARRB1 mRNAs in TSC2^NEG cells; these cells lost their ability to respond to stimulation by endothelin. We analyzed the effects of endothelin receptor antagonists alone or in combination with rapamycin, an mTOR inhibitor, on proliferation and migration of LAM cells. Rapamycin treatment of TSC2^NEG cells significantly reduced cell proliferation or migration, while none of the tested inhibitors of EDN receptors impaired these functions. We showed that TSC2^NEG cells have acquired a transformed phenotype as showed by their ability to grow as spheroids in semi-solid medium and that unlike endothelin receptors antagonists, rapamycin reduced anchorage-independent cell growth and prevented expansion of TSC2^NEG spheroids.

A Retrospective Analysis of Adherence to Risk Evaluation and Mitigation Strategies Requirements for Pulmonary Arterial Hypertension Drugs

Purpose: The purpose of this quality-improvement project was to assess risk evaluation and mitigation strategies (REMS) program compliance for pulmonary arterial hypertension (PAH) drugs following the initiation of more rigid protocols and informatics changes. The primary objective of the study was to determine the effects of these changes on overall compliance of the REMS program requirements. Method: This was a single-center, retrospective evaluation of protocols and informatics updates that were developed to increase compliance with REMS programs for four drugs used to treat PAH. Two separate time periods were examined for comparison: the preinformatics period, January 2015 to February 2016, and the postinformatics period, October 2016 to April 2017. To be included in the study, patients must have been at least 18 years of age and have been ordered one of the following agents: riociguat, macitentan, bosentan, or ambrisentan. Results: Overall, 94 patients were evaluated with 50 in the preinformatics group and 44 in the postinformatics group. The overall mean age of included patients was 55 years, 57.9% of patients were white, 69.1% were female, and 43.6% were prescribed ambrisentan during the study period. The primary composite endpoint of adherence to REMS protocol (pregnancy tests performed within 30 days of medication initiation for female patients of childbearing potential, liver function tests [LFTs] ordered within 30 days of bosentan initiation, and initiation of therapy order documented by an attending provider enrolled in the REMS program) showed an overall improvement in the postinformatics period, 95% vs 71% (P = .07).There was a statistically significant increase in pregnancy tests performed within 30 days of medication order in the postinformatics period (36.4% vs 100%; P = .01). Furthermore, during the postinformatics period, the number of documented interventions (iVents) performed by a pharmacist was 90.9%. Conclusion: Initiation of more rigid ordering protocols for the endothelin receptor antagonists (macitentan, bosentan, or ambrisentan) and riociguat improved pharmacist and physician compliance with REMS requirements.

Early versus late cardiac remodeling during right ventricular pressure load and impact of preventive versus rescue therapy with endothelin-1 receptor blockers

Pulmonary artery banding (PAB) causes right ventricular (RV) dysfunction, biventricular fibrosis, and apoptosis, which are attenuated by endothelin-1 receptor blockade (ERB). Little is known about the time course of remodeling and whether early versus late ERB confers improved outcome. PAB was performed in five groups of rabbits: Shams, 3-wk PAB (3W), 6-wk PAB (6W), 6-wk PAB + ERB administered from day 1 (6WERB1), and 6-wk PAB + ERB administered from day 21 (6WERB21). Biventricular development of profibrotic molecular signaling, fibrosis, apoptosis, and conductance catheter and echocardiography function were studied. Thirty-three rabbits [ n = 6–7 per group; 3.00 (0.23) kg, mean (SD)] developed half to full systemic RV pressures. Biventricular profibrotic signaling and collagen deposition [RV collagen: Shams 3.8 (0.58) vs. 3W 8.69 (2.52) vs. 6W 8.83 (4.02)%, P < 0.005] and apoptosis [RV: Shams 8.32 (3.2) vs. 3W 55.95 (47.55) vs. 6W 38.85 (17.26) apoptotic cells per microfield, P < 0.0005] increased with PAB. Early and late ERB attenuated fibrosis [RV: 6WERB1 5.55 (1.18), 6WERB21 5.63 (0.72)%] and apoptosis [RV: 6WERB1 11.1 (5.25), 6WERB21 20.24 (7.16) apoptotic cells per microfield, P < 0.0001 vs. 6W]. RV dimensions progressively increased at 3W and 6W and decreased with early ERB [end-diastolic dimensions: Shams 0.4 (0.13) vs. 3W 0.55 (0.78) vs. 6W 0.78 (0.25) vs. 6WERB1 0.71 (0.26) vs. 6WERB21 0.49 (0.23) cm, P < 0.05]. Despite increased RV contractility with PAB [RV end-systolic pressure-volume relationship: Shams 3.76 (1.76) vs. 3W 12.21 (3.44) vs. 6W 19.4 (6.88) mmHg/ml], biventricular function and cardiac output [Shams 196.1 (39.73) vs. 3W 149.9 (34.82) vs. 6W 151 (31.69) ml/min] worsened in PAB groups and improved with early and late ERB [6WERB1 202.8 (26.8), 6WERB21 194.8 (36.93) ml/min, P < 0.05 vs. PAB]. In conclusion, RV pressure overload induces early biventricular fibrosis, apoptosis, remodeling, and dysfunction that worsens with persistent RV hypertension. This remodeling is attenuated by early and late ERB.

NEW & NOTEWORTHY Our results in a rabbit model of progressive right ventricular (RV) pressure loading indicate that biventricular fibrosis, apoptosis, and dysfunction are already present when RV hypertension is reached at 3 wk of progressive pulmonary artery banding. These findings worsen with persistent RV hypertension to 6 wk and are attenuated with both early and late endothelin-1 receptor blockade, with some advantages to early therapy. These findings highlight the role of endothelin-1 in driving biventricular remodeling secondary to RV hypertension and suggest that early therapy with an endothelin-1 receptor blocker may be beneficial in attenuating biventricular remodeling but that late therapy is also effective.

The Effect of Endothelin Receptor Antagonists in Patients with Eisenmenger Syndrome: A Systematic Review

INTRODUCTION

The efficacy of endothelin receptor antagonists (ERAs) in the management of Eisenmenger syndrome (ES) remains controversial. The aim of this study is to systemically review the safety and effects of ERAs in improving the quality of life and basic cardiac functions of these patients.

METHODS

Twelve databases were searched, including PubMed, Web of Science, Scopus, Virtual Health Library, World Health Organization (WHO) Global Health Library, Google Scholar, POPLINE, Systems for Information of Grey Literature in Europe, New York Academy of Medicine, ClinicalTrials.gov, metaRegister of Controlled Trials and the WHO International Clinical Trials Registry Platform, through August 2016. We included randomized clinical trials addressing the effect of ERAs on cardiac functions in patients with ES. The quality of studies was assessed using the Cochrane Collaboration tool.

RESULTS

We included two trials represented by four papers, of which three papers reported the efficacy of bosentan against placebo and one paper reported the results of a combination of bosentan and sildenafil versus placebo and bosentan. One trial showed a significant effect of bosentan treatment over placebo on indexed pulmonary vascular resistance and mean pulmonary artery pressure, but a non-significant increase in 6-min walk distance and a non-significant effect on systemic pulse oximetry. The other trial reported the safe but non-significant effect of combination therapy of bosentan and sildenafil compared with bosentan and placebo.

CONCLUSIONS

This study demonstrated safety and improved hemodynamic effects of bosentan in ES, with a controversial effect on exercise capacity. Further randomized controlled trials with longer follow-up duration are needed to confirm these results.

Severe pulmonary arterial hypertension associated with congenital cardiac shunts: evolution under specific treatment

Objective: The aim of this study was to compare the effects of Sildenafil, Bosentan and combined therapy in patients with congenital cardiac shunts associated pulmonary artery hypertension (CCS-PAH). Design: Prospective observational study (February 2011 - January 2014) with a historical control group (January 2009 - January 2011). Setting: "CC Iliescu" Institute for Emergency Cardiovascular Diseases of Bucharest, a tertiary university-affiliated center. Patients: All cases with CCS-PAH. Interventions: Specific vasodilatory therapy: Sildenafil, Bosentan or combined therapy. Outcome Measures: The primary outcome was the overall survival at 24 months. Results: Out of 108 patients with pulmonary arterial hypertension, there were 79 patients with CCS-PAH, 55 presenting a severe form of the disease. The mean age of the patients was 34.42±21.15 years, with 37 (67,3%) female patients. 23 patients received specific vasodilatory treatment (thirteen Sildenafil, seven Bosentan, three combined treatment), with 32 patients in the control group, without specific vasodilatory therapy. The specific vasodilatory therapy was associated with improved WHO/ NYHA functional class (p=0.025), oxygen saturation at the end of the six-minute walk test (p=0.011), decreased pulmonary artery systolic (p=0.002) and diastolic (p=0.004) pressures, and an increased S' wave in Tissue Doppler Imaging (p=0.008). Conclusions: Despite the complexity of CCS-PAH, with a complex constellation of underlying congenital heart defects, there are short-term benefits of a specific vasodilatory therapy.

Idiopathic pre-capillary pulmonary hypertension in patients with end-stage kidney disease: effect of endothelin receptor antagonists

Background

We examined the prevalence, prognosis, and effect of endothelin receptor antagonists on survival in end-stage kidney disease patients with idiopathic pre-capillary pulmonary hypertension.

Methods

We investigated 1988 end-stage kidney disease patients in Toujinkai Hospital from January 1, 2001 to December 31, 2014. Pulmonary hypertension was screened by symptoms (dyspnea, hypotension, or near syncope) and echocardiography, and diagnosed by computed tomography with enhancement, pulmonary flow scintigraphy, and right heart catheterization.

Results

Fifteen patients (67 ± 11 years; 12 women and 3 men) were diagnosed as idiopathic pre-capillary pulmonary hypertension; mean pulmonary arterial pressure, pulmonary vascular resistance, or pulmonary artery wedge pressure were 55 ± 11 mmHg, 7.5 ± 2.9 Woods units, or 12 ± 2 mmHg, respectively. Of the 15 patients, 14 received hemodialysis, and 1 was in a pre-dialysis stage. Patients were followed through December 31, 2015, and 11 died of heart failure; their mean survival time was 26.4 ± 21.0 months. Endothelin receptor antagonists were used for 11 patients, and mean survival times were 57.3 ± 12.1 months in patients with endothelin receptor antagonists and 7.5 ± 2.1 months in those without. In the Kaplan–Meier analysis, heart failure death-free survival rates were higher in patients with endothelin receptor antagonists than in those without (P < 0.001); 100 versus 25 % at one year and 71 versus 0 % at 3 years.

Conclusion

The prognosis of idiopathic pre-capillary pulmonary hypertension seems to be poor in end-stage kidney disease patients. Administration of endothelin receptor antagonists might improve the survival by inhibiting heart failure death.

Registration of clinical trials This study was registered to the ClinicalTrials.gov (https://clinicaltrials.gov/): protocol identifier, NCT02743091.

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

BACKGROUND

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.

OBJECTIVES

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.

SEARCH METHODS

CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE and CINAHL databases were searched until December 2015.

SELECTION CRITERIA

Randomised, cluster-randomised or quasi-randomised controlled trials were eligible.

DATA COLLECTION AND ANALYSIS

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.

MAIN RESULTS

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.

AUTHORS' CONCLUSIONS

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.

Comparative Effectiveness of Oral Medications for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease that imposes a significant burden on patients. Although multiple treatment options for PAH are available, head-to-head comparisons are difficult to conduct. Network meta-analysis (NMA) can be a useful alternative for direct comparison to estimate the relative effectiveness of multiple treatments. The objective of the present study was to conduct a systematic review and NMA to evaluate the relative effectiveness among oral PAH medications.Data collection was performed by searching the Cochrane Central Register of Controlled Trials (CENTRAL) and Ichushi-Web. Randomized controlled trials (RCTs) assessing at least 1 of the following 3 outcome measurements; 6-minute walk distance test (6MWD), WHO functional class (WHOFC), and mean pulmonary artery pressure (mPAP) were included (PROSPERO registration number: CRD42015016557). Outcomes were evaluated by estimating the differences in the mean change from baseline or by estimating the odds ratios. Analyses were performed using WinBUGS 1.4.3.Seven double-blind RCTs were eligible. NMA results showed similar improvements in 6MWD for all medications assessed. Bosentan and sildenafil caused a statistically significant improvement in WHOFC compared to other medications.The relative effectiveness of oral PAH medications could be compared using NMA, which suggested the superiority of bosentan and sildenafil in the improvement of WHOFC.

Endothelin-Receptor Antagonists beyond Pulmonary Arterial Hypertension: Cancer and Fibrosis

The endothelin axis and in particular the two endothelin receptors, ETA and ETB, are targets for therapeutic intervention in human diseases. Endothelin-receptor antagonists are in clinical use to treat pulmonary arterial hypertension and have been under clinical investigation for the treatment of several other diseases, such as systemic hypertension, cancer, vasospasm, and fibrogenic diseases. In this Perspective, we review the molecules that have been evaluated in human clinical trials for the treatment of pulmonary arterial hypertension, as well as other cardiovascular diseases, cancer, and fibrosis. We will also discuss the therapeutic consequences of receptor selectivity with regard to ETA-selective, ETB-selective, or dual ETA/ETB antagonists. We will also consider which chemical characteristics are relevant to clinical use and the properties of molecules necessary for efficacy in treating diseases against which known molecules displayed suboptimal efficacy.

Peroxisome Proliferator-Activated Receptor γ and microRNA 98 in Hypoxia-Induced Endothelin-1 Signaling

Endothelin-1 (ET-1) plays a critical role in endothelial dysfunction and contributes to the pathogenesis of pulmonary hypertension (PH). We hypothesized that peroxisome proliferator-activated receptor γ (PPARγ) stimulates microRNAs that inhibit ET-1 and pulmonary artery endothelial cell (PAEC) proliferation. The objective of this study was to clarify molecular mechanisms by which PPARγ regulates ET-1 expression in vitro and in vivo. In PAECs isolated from patients with pulmonary arterial hypertension, microRNA (miR)-98 expression was reduced, and ET-1 protein levels and proliferation were increased. Similarly, hypoxia reduced miR-98 and increased ET-1 levels and PAEC proliferation in vitro. In vivo, hypoxia reduced miR-98 expression and increased ET-1 and proliferating cell nuclear antigen (PCNA) levels in mouse lung, derangements that were aggravated by treatment with the vascular endothelial growth factor receptor antagonist Sugen5416. Reporter assays confirmed that miR-98 binds directly to the ET-1 3'-untranslated region. Compared with littermate control mice, miR-98 levels were reduced and ET-1 and PCNA expression were increased in lungs from endothelial-targeted PPARγ knockout mice, whereas miR-98 levels were increased and ET-1 and PCNA expression was reduced in lungs from endothelial-targeted PPARγ-overexpression mice. Gain or loss of PPARγ function in PAECs in vitro confirmed that alterations in PPARγ were sufficient to regulate miR-98, ET-1, and PCNA expression. Finally, PPARγ activation with rosiglitazone regimens that attenuated hypoxia-induced PH in vivo and human PAEC proliferation in vitro restored miR-98 levels. The results of this study show that PPARγ regulates miR-98 to modulate ET-1 expression and PAEC proliferation. These results further clarify molecular mechanisms by which PPARγ participates in PH pathogenesis and therapy.

Comparison of Treatment Response in Idiopathic and Connective Tissue Disease-associated Pulmonary Arterial Hypertension

RATIONALE

Studies suggest that patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) have a poorer treatment response to therapies for PAH compared with patients with idiopathic PAH (IPAH), but individual randomized controlled trials (RCTs) have been underpowered to examine differences within these subgroups.

OBJECTIVES

To compare the effect of therapy for PAH in CTD-PAH versus IPAH.

METHODS

We obtained individual participant data from phase III placebo-controlled RCTs of therapies for PAH submitted to the U.S. Food and Drug Administration for drug approval. A treatment-by-diagnosis interaction term evaluated differences in treatment response between CTD-PAH and IPAH. Outcomes included change in 6-minute-walk distance (∆6MWD) from baseline to 12 weeks, clinical worsening, and all-cause mortality.

MEASUREMENTS AND MAIN RESULTS

The study sample included 827 participants with CTD-PAH and 1,935 with IPAH from 11 RCTs. Patients with CTD-PAH had less improvement in 6MWD when assigned to active treatment versus placebo compared with patients with IPAH (difference in treatment effect on ∆6MWD in CTD-PAH vs. IPAH, -17.3 m; 90% confidence interval, -31.3 to -3.3; P for interaction = 0.043). Treatment was less effective in reducing the occurrence of clinical worsening in CTD-PAH versus IPAH (P for interaction = 0.012), but there was no difference in the placebo-adjusted effect of treatment on mortality (P for interaction = 0.65).

CONCLUSIONS

Treatment for PAH was less effective in CTD-PAH compared with IPAH in terms of increasing 6MWD and preventing clinical worsening. The heterogeneity of treatment response supports the need for identifying therapies that are more effective for CTD-PAH.

Dual Endothelin Receptor Blockade Abrogates Right Ventricular Remodeling and Biventricular Fibrosis in Isolated Elevated Right Ventricular Afterload

Background

Pulmonary arterial hypertension is usually fatal due to right ventricular failure and is frequently associated with co-existing left ventricular dysfunction. Endothelin-1 is a powerful pro-fibrotic mediator and vasoconstrictor that is elevated in pulmonary arterial hypertension. Endothelin receptor blockers are commonly used as pulmonary vasodilators, however their effect on biventricular injury, remodeling and function, despite elevated isolated right ventricular afterload is unknown.

Methods

Elevated right ventricular afterload was induced by progressive pulmonary artery banding. Seven rabbits underwent pulmonary artery banding without macitentan; 13 received pulmonary artery banding + macitentan; and 5 did not undergo inflation of the pulmonary artery band (sham-operated controls). Results: Right and left ventricular collagen content was increased with pulmonary artery banding compared to sham-operated controls and ameliorated by macitentan. Right ventricular fibrosis signaling (connective tissue growth factor and endothelin-1 protein levels); extra-cellular matrix remodeling (matrix-metalloproteinases 2 and 9), apoptosis and apoptosis-related peptides (caspases 3 and 8) were increased with pulmonary artery banding compared with sham-operated controls and decreased with macitentan.

Conclusion

Isolated right ventricular afterload causes biventricular fibrosis, right ventricular apoptosis and extra cellular matrix remodeling, mediated by up-regulation of endothelin-1 and connective tissue growth factor signaling. These pathological changes are ameliorated by dual endothelin receptor blockade despite persistent elevated right ventricular afterload.

Underrated value of repeated right heart catheterization in pulmonary hypertension with heart failure-a case of persisted pulmonary arterial hypertension after treatment for biventricular failure

Pulmonary hypertension (PH) is a common complication of left heart disease and its presence in patients with heart failure predicts worse clinical outcomes. Specific agents targeting pulmonary arterial hypertension (PAH) have been developed over the last few years, but the efficacy of these agents in pulmonary hypertension due to left heart disease (PH-LHD) is uncertain. We report a case of idiopathic pulmonary arterial hypertension (IPAH) initially presented with biventricular failure, which was misdiagnosed as PH-LHD. A 31-year-old man who had a history of recurrent hemoptysis was referred to our center with biventricular failure. Right heart catheterization (RHC) showed elevated mean pulmonary arterial pressure (mPAP) and pulmonary capillary wedge pressure (PCWP). He was diagnosed as having PH-LHD, specifically combined post-capillary and precapillary PH (CpcPH). We treated him for 2 years with diuretics, a beta blocker, an angiotensin-converting enzyme (ACE) inhibitor, and sildenafil, which was added to treat CpcPH. A follow-up echocardiography showed that biventricular function had improved, but not PH. A second RHC revealed elevated mPAP and normal PCWP, which made us change the diagnosis to IPAH. In conclusion, it is important to perform repeated RHC in CpcPH patients after the improvement of left heart dysfunction to distinguish CpcPH from IPAH.

An assessment of randomized controlled trials (RCTs) for non-communicable diseases (NCDs): more and higher quality research is required in less developed countries

Research is crucial to implement evidence-based health interventions for control of non-communicable diseases (NCDs). This study aims to assess main features of randomized controlled trials (RCTs) for control of NCDs, and to identify gaps in clinical research on NCDs between high-income and less developed countries. The study included 1177 RCTs in 82 Cochrane Systematic reviews (CSRs) and evaluated interventions for adults with hypertension, diabetes, stroke, or heart diseases. Multivariate logistic regression analyses were conducted to explore factors associated with risk of bias in included RCTs. We found that 78.2% of RCTs of interventions for major NCDs recruited patients in high-income countries. The number of RCTs included in the CSRs was increasing over time, and the increasing speed was more noticeable for RCTs conducted in middle-income countries. RCTs conducted in less developed countries tended to be more recently published, less likely to be published in English, with smaller sample sizes, and at a higher risk of bias. In conclusion, there is still a lack of research evidence for control of NCDs in less developed countries. To brace for rising NCDs and avoid waste of scarce research resources, not only more but also higher quality clinical trials are required in low-and-middle-income countries.

Endothelin@25 - new agonists, antagonists, inhibitors and emerging research frontiers: IUPHAR Review 12

Since the discovery of endothelin (ET)-1 in 1988, the main components of the signalling pathway have become established, comprising three structurally similar endogenous 21-amino acid peptides, ET-1, ET-2 and ET-3, that activate two GPCRs, ETA and ETB . Our aim in this review is to highlight the recent progress in ET research. The ET-like domain peptide, corresponding to prepro-ET-193-166 , has been proposed to be co-synthesized and released with ET-1, to modulate the actions of the peptide. ET-1 remains the most potent vasoconstrictor in the human cardiovascular system with a particularly long-lasting action. To date, the major therapeutic strategy to block the unwanted actions of ET in disease, principally in pulmonary arterial hypertension, has been to use antagonists that are selective for the ETA receptor (ambrisentan) or that block both receptor subtypes (bosentan). Macitentan represents the next generation of antagonists, being more potent than bosentan, with longer receptor occupancy and it is converted to an active metabolite; properties contributing to greater pharmacodynamic and pharmacokinetic efficacy. A second strategy is now being more widely tested in clinical trials and uses combined inhibitors of ET-converting enzyme and neutral endopeptidase such as SLV306 (daglutril). A third strategy based on activating the ETB receptor, has led to the renaissance of the modified peptide agonist IRL1620 as a clinical candidate in delivering anti-tumour drugs and as a pharmacological tool to investigate experimental pathophysiological conditions. Finally, we discuss biased signalling, epigenetic regulation and targeting with monoclonal antibodies as prospective new areas for ET research.

Long-term survival of patients with pulmonary arterial hypertension recovering to World Health Organization functional class I or II: a historical comparison between intravenous epoprostenol and oral agents

Background

Intravenous epoprostenol is the only drug proved in a randomized study to reduce mortality in patients with idiopathic pulmonary arterial hypertension (PAH). However, administration of this drug has procedural difficulties and a risk of sepsis. Oral drugs provide simple treatment, but their benefit for survival has not been proven. A recovery of patients with PAH to World Health Organization functional class (WHO-FC) I or II may predict favorable survival.

Methods

Survival analyses were performed on a historical cohort of 41 patients with PAH. The patients were 43 ± 22 years old, 23 had idiopathic or heritable PAH, and 18 had connective tissue disease-associated PAH. The baseline was defined as the initial visit to a medical facility.

Results

The median duration of follow-up was 1276 days (108 to 5389 days) and 21 patients died during this period. The estimated survival times for patients who received intravenous epoprostenol and did and did not recover to WHO-FC I or II were 4371 ± 577 days and 1172 ± 404 days, respectively. These times for patients who were not treated with intravenous epoprostenol and did and did not recover to WHO-FC I or II were 4717 ± 554 days and 925 ± 230 days, respectively. A Cox proportional hazard analysis gave a hazard ratio for death after recovery to WHO-FC I or II of 0.07 (P < 0.001). In contrast, use of intravenous epoprostenol was not a significant factor affecting survival (P = 0.96).

Conclusions

Patients with PAH who achieve recovery to WHO-FC I or II without use of intravenous epoprostenol have similar survival to those who reach the same WHO-FC with use of intravenous epoprostenol. Benign survival of patients with PAH who have recovered to WHO-FC I or II may extend for several years after onset of the disease.

Modulation of endothelin receptors in the failing right ventricle of the heart and vasculature of the lung in human pulmonary arterial hypertension

AIMS

In pulmonary arterial hypertension (PAH), increases in endothelin-1 (ET-1) contribute to elevated pulmonary vascular resistance which ultimately causes death by right ventricular (RV) heart failure. ET antagonists are effective in treating PAH but lack efficacy in treating left ventricular (LV) heart failure, where ETA receptors are significantly increased. The aim was to quantify the density of ETA and ETB receptors in cardiopulmonary tissue from PAH patients and the monocrotaline (MCT) rat, which recapitulates some of the pathophysiological features, including increased RV pressure.

MAIN METHODS

Radioligand binding assays were used to quantify affinity, density and ratio of ET receptors.

KEY FINDINGS

In RV from human PAH hearts, there was a significant increase in the ratio of ETA to ETB receptors compared with normal hearts. In the RV of the MCT rat, the ratio also changed but was reversed. In both human and rat, there was no change in LV. In human PAH lungs, ETA receptors were significantly increased in the medial layer of small pulmonary arteries with no change detectable in MCT rat vessels.

SIGNIFICANCE

Current treatments for PAH focus mainly on pulmonary vasodilatation. The increase in ETA receptors in arteries provides a mechanism for the beneficial vasodilator actions of ET antagonists. The increase in the ratio of ETA in RV also implicates changes to ET signalling although it is unclear if ET antagonism is beneficial but the results emphasise the unexploited potential for therapies that target the RV, to improve survival in patients with PAH.