Clinical Adverse Effects of Endothelin Receptor Antagonists: Insights From the Meta-Analysis of 4894 Patients From 24 Randomized Double-Blind Placebo-Controlled Clinical Trials

Emerging Drug Classes and Their Potential Use in Hypertension

Despite the availability of multiple antihypertensive drugs targeting the different pathways implicated in its pathophysiology, hypertension remains poorly controlled worldwide, and its prevalence is increasing because of the aging of the population and the obesity epidemic. Although nonadherence to treatment contributes to uncontrolled hypertension, it is likely that not all the pathophysiological mechanisms are neutralized by the various classes of antihypertensive treatment currently available, and, the counter-regulatory mechanisms triggered by these treatments may decrease their blood pressure–lowering effect. The development of new antihypertensive drugs acting on new targets, with different modes of action, therefore, remains essential, to improve blood pressure control and reduce the residual burden of cardiovascular risks further. However, the difficulties encountered in the conception, development, costs, and delivery to the market of new classes of antihypertensive agents highlights the hurdles that must be overcome to release and to evaluate their long-term safety and efficacy for hypertension only, especially because of the market pressure of cheap generic drugs. New chemical entities with blood pressure–lowering efficacy are thus being developed more for heart failure or diabetic kidney disease, 2 diseases pathophysiologically associated with hypertension. These include dual angiotensin II receptor-neprilysin inhibitors, soluble guanylate cyclase stimulators, nonsteroidal dihydropyridine-based mineralocorticoid receptor antagonists, as well as sodium-glucose cotransporter 2 inhibitors. However, centrally acting aminopeptidase A inhibitors and endothelin receptor antagonists have a dedicated program of development for hypertension. All these emergent drug classes and their potential use in hypertension are reviewed here.

Treatment Discontinuation or Interruption in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease, which can be potentially fatal. The management of a complex disease like PAH requires a multidisciplinary approach from a team consisting of physicians, nurses, social workers, and pharmacists. Adherence to PAH-specific therapy is one of the key factors in the management of this disease. Poor adherence to treatment is a common problem in PAH as it is in many chronic diseases. Management of medication interruptions is a challenge in patients with PAH that can lead to negative consequences. However, for most PAH-specific drugs, there are no clear guidelines on how to manage temporary or abrupt medication discontinuations. In this review, we summarized the available literature and provide suggestions on how to manage interruptions of PAH-specific therapies.

G-Protein-Coupled Receptors in Heart Disease

GPCRs (G-protein [guanine nucleotide-binding protein]-coupled receptors) play a central physiological role in the regulation of cardiac function in both health and disease and thus represent one of the largest class of surface receptors targeted by drugs. Several antagonists of GPCRs, such as βARs (β-adrenergic receptors) and Ang II (angiotensin II) receptors, are now considered standard of therapy for a wide range of cardiovascular disease, such as hypertension, coronary artery disease, and heart failure. Although the mechanism of action for GPCRs was thought to be largely worked out in the 80s and 90s, recent discoveries have brought to the fore new and previously unappreciated mechanisms for GPCR activation and subsequent downstream signaling. In this review, we focus on GPCRs most relevant to the cardiovascular system and discuss traditional components of GPCR signaling and highlight evolving concepts in the field, such as ligand bias, β-arrestin-mediated signaling, and conformational heterogeneity.

Novel Therapeutic Approaches Targeting the Renin-Angiotensin System and Associated Peptides in Hypertension and Heart Failure

Despite the success of renin-angiotensin system (RAS) blockade by angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor (AT1R) blockers, current therapies for hypertension and related cardiovascular diseases are still inadequate. Identification of additional components of the RAS and associated vasoactive pathways, as well as new structural and functional insights into established targets, have led to novel therapeutic approaches with the potential to provide improved cardiovascular protection and better blood pressure control and/or reduced adverse side effects. The simultaneous modulation of several neurohumoral mediators in key interconnected blood pressure-regulating pathways has been an attractive approach to improve treatment efficacy, and several novel approaches involve combination therapy or dual-acting agents. In addition, increased understanding of the complexity of the RAS has led to novel approaches aimed at upregulating the ACE2/angiotensin-(1-7)/Mas axis to counter-regulate the harmful effects of the ACE/angiotensin II/angiotensin III/AT1R axis. These advances have opened new avenues for the development of novel drugs targeting the RAS to better treat hypertension and heart failure. Here we focus on new therapies in preclinical and early clinical stages of development, including novel small molecule inhibitors and receptor agonists/antagonists, less conventional strategies such as gene therapy to suppress angiotensinogen at the RNA level, recombinant ACE2 protein, and novel bispecific designer peptides.

Safety and tolerability of macitentan in the management of pulmonary arterial hypertension: an update

Macitentan is a medication in the endothelin receptor antagonist class, approved for treatment of pulmonary arterial hypertension in 2013 based on the results of the pivotal SERAPHIN Trial (Study with an Endothelin Receptor Antagonist in Pulmonary arterial Hypertension to Improve cliNical outcome). Macitentan was shown in initial trials to reduce the likelihood of a morbidity/mortality event. Real-world use of this medication additionally reveals a reduced risk of hospitalizations related to pulmonary arterial hypertension, improved health-related quality of life scores, potential clinical utility in other conditions (such as chronic thromboembolic pulmonary hypertension and pulmonary hypertension related to congenital heart disease), and has a similar safety profile as demonstrated in initial trials.

Castration Determines the Efficacy of ETAR Blockade in a Mouse Model of Prostate Cancer Bone Metastasis

Bone metastasis is a painful complication of advanced prostate cancer. Endothelin-1 is a tumor-secreted factor that plays a central role in osteoblast activation and the osteosclerotic response of prostate cancer metastatic to bone. Antagonists that block the activation of the endothelin A receptor (ETAR), located on osteoblasts, reduce osteoblastic bone lesions in animal models of bone metastasis. However, ETAR antagonists demonstrated limited efficacy in clinical trials of men with advanced prostate cancer who also received standard androgen deprivation therapy (ADT). Previous data from our group suggested that, in a mouse model, ETAR antagonists might only be efficacious when androgen signaling in the osteoblast is lowered beyond the ability of standard ADT. This notion was tested in a mouse model of prostate cancer bone metastasis. Castrated and sham-operated male athymic nude mice underwent intracardiac inoculation of the ARCaPM castration-resistant prostate cancer cell line. The mice were then treated with either the ETAR antagonist zibotentan or a vehicle control to generate four experimental groups: vehicle+sham (Veh+Sham), vehicle+castrate (Veh+Castr), zibotentan+sham (Zibo+Sham), and zibotentan+castrate (Zibo+Castr). The mice were monitored radiographically for the development of skeletal lesions. The Zibo+Castr group had significantly longer survival and a single incidental lesion. Mice in the Zibo+Sham group had the shortest survival and the largest number of skeletal lesions. Survival and skeletal lesions of the Veh+Sham and Veh+Castr groups were intermediate compared with the zibotentan-treated groups. We report a complex interaction between ETAR and androgen signaling, whereby ETAR blockade was most efficacious when combined with complete androgen deprivation.

A network meta-analysis for safety of endothelin receptor antagonists in pulmonary arterial hypertension

Background

Currently, direct comparative safety between endothelin receptor antagonists (ERAs) in pulmonary arterial hypertension (PAH) is limited. Thus, a systematic review with network analysis was conducted.

Methods

An electronic search was performed for randomized controlled trials (RCTs) that reported the interested safety data (abnormal liver function, peripheral edema, and anemia) of ERAs in PAH. Risk ratios (RRs) with their confidence intervals (CIs) and the surface under the cumulative ranking curve (SUCRA) were calculated using a network analysis.

Results

Ten RCTs involving 2,288 patients were included. Compared with placebo, bosentan (RR, 2.93; 95% CI, 1.78-4.84) significantly increased the risk of abnormal liver function, ambrisentan (RR, 1.62; 95% CI, 1.23-2.13) significantly increased the risk of peripheral edema, and macitentan (RR, 3.42; 95% CI, 1.65-7.07) significantly increased the risk of anemia. SUCRA analysis suggested that bosentan 125 mg twice daily had the highest risk of abnormal liver function; ambrisentan 10 mg once daily had the highest risk of peripheral edema; macitentan 10 mg once daily had the highest risk of anemia.

Conclusions

Abnormal liver function (bosentan), peripheral edema (ambrisentan), and anemia (macitentan) were the safety indicators of ERAs in patients with PAH. Different monitoring parameters should be considered for individual ERA.

Leveraging Signaling Pathways to Treat Heart Failure With Reduced Ejection Fraction

Advances in the treatment of heart failure with reduced ejection fraction due to systolic dysfunction are engaging an ever-expanding compendium of molecular signaling targets. Well established approaches modifying hemodynamics and cell biology by neurohumoral receptor blockade are evolving, exploring the role and impact of modulating intracellular signaling pathways with more direct myocardial effects. Even well-tread avenues are being reconsidered with new insights into the signaling engaged and thus opportunity to treat underlying myocardial disease. This review explores therapies that have proven successful, those that have not, those that are moving into the clinic but whose utility remains to be confirmed, and those that remain in the experimental realm. The emphasis is on signaling pathways that are tractable for therapeutic manipulation. Of the approaches yet to be tested in humans, we chose those with a well-established experimental history, where clinical translation may be around the corner. The breadth of opportunities bodes well for the next generation of heart failure therapeutics.

Temporal shifts in fluid in pulmonary hypertension with and without sleep apnea

Overnight extracellular rostral fluid shifts have been shown to be of importance in patients with fluid-retaining states and are associated with a higher prevalence of sleep apnea. Pulmonary hypertension is frequently associated with right ventricular dysfunction and progressive right ventricular failure, and an increased prevalence of sleep apnea has been described. In light of the importance of fluid shifts in the pathophysiology of sleep apnea, we aimed to explore temporal fluid shifts in patients with pulmonary hypertension with and without sleep apnea. Patients with pulmonary hypertension (WHO Group 1 or 4) had overnight extracellular rostral fluid shift assessment before and a minimum of 3 months after initiation of pulmonary hypertension-specific therapy. Fluid shift measurements of extracellular leg, abdominal, thoracic and neck fluid volumes were performed simultaneously. Twenty-nine patients with pulmonary hypertension (age 55 ± 16 years, 69% female) participated. Sleep apnea was diagnosed in 15 subjects (apnea-hypopnea index 14 [8-27] per hr). There were no significant differences in baseline or overnight leg extracellular rostral fluid, abdominal extracellular rostral fluid, thoracic extracellular rostral fluid or neck extracellular rostral fluid between those with and without sleep apnea. There was a significant inverse correlation between the sleep apnea severity and the overnight change in leg extracellular rostral fluid (r = -0.375, p = 0.049). There were no significant differences detected in overnight extracellular rostral fluid shifts from baseline to follow-up. Treatment-naïve patients with pulmonary hypertension both with and without sleep apnea demonstrate overnight extracellular rostral fluid shifts from the legs into the thorax and neck. Pulmonary hypertension-specific treatment, while significantly improving cardiac haemodynamics, had little impact on nocturnal extracellular rostral fluid shifts or the presence of sleep apnea.

Meta-analysis of Stroke and Bleeding Risk in Patients with Various Atrial Fibrillation Patterns Receiving Oral Anticoagulants

Oral anticoagulation therapy (OAT) is a mainstay for stroke prevention in atrial fibrillation (AF) patients. However, whether the risks of stroke/systemic embolic events (SEE) and bleeding events are affected by the type, duration, and frequency of AF in patients receiving OAT has been previously debated. We aimed to determine the risk of stroke/SEE and bleeding events associated with paroxysmal AF compared to persistent or permanent AF among patients who received OAT. Comprehensive literature searches of the Cochrane Library, PubMed/MEDLINE, and EMBASE databases were conducted from inception to July 2018. In total, 495 records were retrieved, of which 6 phase III randomized controlled trials (RCTs) focusing on the efficacy and safety of OAT in AF patients were ultimately evaluated and included. Among 70,447 AF patients, 15,028 (21.3%) patients had paroxysmal and 55,419 (78.7%) had persistent or permanent AF. Compared to persistent or permanent AF, the incidence of stroke/SEE was lower in paroxysmal AF patients (risk ratio [RR] 0.79, 95% confidence interval [CI] 0.71 to 0.88, P <0.00001, I² = 0%). Overall, all-cause mortality was also lower in paroxysmal AF than in persistent or permanent AF patients (RR 0.72, 95% CI 0.66 to 0.79, P <0.00001, I² =0%). Annualized major bleeding rates were similar across AF types (RR 1.06, 95% CI 0.96 to 1.17, P = 0.22, I ²= 35%). In conclusion, in patients with moderate-to-high risk of stroke receiving anticoagulation, those with paroxysmal AF have a lower risk of stroke, systemic embolism, and mortality but similar risk of major hemorrhage compared to persistent or permanent AF patients.

Endothelin-1 levels and cardiovascular events

Circulating plasma levels of endothelin-1 and related peptides generated during the synthesis of endothelin-1 from its precursor molecule pre-proendothelin-1 have been widely studied as potential risk markers for cardiovascular events. The associations of endothelin-1 with aging, blood pressure, lung function, and chronic kidney disease have been described, as have relations between endothelin-1 levels and evidence of cardiac remodeling, including increased left atrial diameter and increased left ventricular mass. Endothelin-1 has been studied as a predictor of and prognostic marker in coronary artery disease, myocardial infarction, and heart failure. The relationship of endothelin-1 levels to mortality in the general population has also been explored. This review examines the current state of knowledge of circulating endothelin-1 levels as they relate to cardiovascular events and prognosis, and explores future directions for research, including using endothelin-1 or related peptide levels to guide personalized treatment regimens and to select patients for primary prevention strategies.

Decreased risk of renal impairment in atrial fibrillation patients receiving non-vitamin K antagonist oral anticoagulants: A pooled analysis of randomized controlled trials and real-world studies

BACKGROUND

Patients with warfarin have a potential risk of warfarin-related nephropathy, which could result in the discontinuation of anticoagulation therapy. The question of whether non-vitamin K antagonist oral anticoagulants (NOACs) use is associated with increased risk of renal impairment in atrial fibrillation (AF) patients remains unanswered.

METHODS

Studies were systematically searched through Medline, Embase, Cochrane Library databases, and ClinicalTrials.gov Website. Randomized controlled trials (RCTs) reporting renal impairment events and observational nationwide database studies presenting adjusted hazard ratio (HR) in AF patients with NOACs were identified. The Primacy outcome was renal impairment, defined as a composite of any renal disorder. The secondary outcomes were narrow definition of renal failure (including renal failure, acute renal failure, chronic renal failure, acute prerenal failure and postrenal failure) and individual renal impairment reported in involved studies. HR and 95% confidence intervals (95%CI) were calculated using fixed- or random-effects models according to the extent of heterogeneity. Subgroup analyses were conducted according to individual NOACs, study types and different controls.

RESULTS

Totally, 189,483 patients from 11 RCTs and 3 observational database studies were included in the analysis (119,188 patients with NOACs and 70,295 patients with vitamin K Antagonists or acetylsalicylic acid). Overall results indicated a significantly lower risk of renal impairment in AF patients with NOACs versus VKAs/acetylsalicylic acid (HR: 0.67, 95%CI: 0.62-0.73). Results of narrow definition of renal impairment were accordant with the primacy outcome (HR: 0.65, 95%CI: 0.60-0.71). Compared with VKAs or acetylsalicylic acid, dabigatran (HR: 0.64, 95%CI: 0.56-0.72), rivaroxaban (HR: 0.66, 95%CI: 0.55-0.77) and apixaban (HR: 0.73, 95%CI: 0.59-0.87) were all associated with a significantly lower risk of renal impairment, with the exception of edoxaban (HR: 0.79, 95%CI: 0.30-1.27).

CONCLUSIONS

Patients with NOACs might bring about a lower risk of renal impairment compared to VKA or acetylsalicylic acid. Further specialized designs of RCTs and real-world studies on evaluation of renal function are warranted to obtain a robust result on this issue.

Endothelin-receptor antagonists in the management of pulmonary arterial hypertension: where do we stand?

Pulmonary arterial hypertension, a disease largely neglected until a few decades ago, is presently the object of intense studies by several research teams. Despite considerable progress, pulmonary arterial hypertension remains a major clinical problem, because it is not always easy to diagnose, treat, and prevent. The disease was considered incurable until the late 1990s, when Epoprostenol was introduced as the first tool against this illness. More recently, therapy for pulmonary arterial hypertension gained momentum after publication of the SERAPHIN and AMBITION trials, which also highlighted the importance of upfront therapy. This review also focuses on recent substudies from these trials and progress in drugs targeting the endothelin pathway. Future perspectives with regard to endothelin-receptor antagonists are also discussed.

Non-vitamin K Antagonist Oral Anticoagulants and Cognitive Impairment in Atrial Fibrillation: Insights From the Meta-Analysis of Over 90,000 Patients of Randomized Controlled Trials and Real-World Studies

Background: The relationship between the use of non-vitamin K antagonist oral anticoagulants (NOACs) and the impairment of cognition in atrial fibrillation (AF) remains unknown. Methods: A comprehensive database search of Medline, Embase, Cochrane Library databases, and ClinicalTrials.gov Website was performed for randomized controlled trials (RCTs) reporting cognitive impairment events and observational nationwide database studies reporting adjusted hazard ratio (HR) in AF patients with NOACs. The primacy outcome was a composite of any cognitive impairment. Summary of HRs and 95% confidence intervals (95%CI) were calculated using the fixed- and random-effects models. Subgroup analyses were undertaken according to the individual NOACs, study types, and duration of follow-up. Results: Finally, eight studies including 97,595 patients (77,643 patients in 6 RCTs and 19,952 patients in 2 observational database studies) met the inclusion criteria, among which 55,337 (56.7%) patients were receiving NOACs and 42,258 (43.3%) patients were receiving vitamin K Antagonists (VKAs) or acetylsalicylic acid. The results showed a borderline significant association between the use of NOACs and the lower risk of cognitive impairment when compared with VKAs/ acetylsalicylic acid (HR: 0.80, 95%CI: 0.63-0.98 for fixed-effects model; HR: 0.77; 95%CI: 0.53-1.01 for random-effects model), with no significant heterogeneity between the studies (I ² = 39.4%, P = 0.12). The results were consistent across the key subgroups (P _interaction > 0.05 for each). Conclusions: The results indicated that the use of NOACs might lower the tendency on the risk of cognitive impairment in comparison to VKAs/acetylsalicylic acid, and further RCTs and real-world studies are required on an urgent basis to obtain a robust result.

Net Clinical Benefit of Non-vitamin K Antagonist Oral Anticoagulants for Venous Thromboembolism Prophylaxis in Patients With Cancer: A Systematic Review and Trade-Off Analysis From 9 Randomized Controlled Trials

Venous thromboembolism (VTE) is highly prevalent in patients with cancer. Non-vitamin K antagonist oral anticoagulants (NOACs), directly targeting the enzymatic activity of thrombin or factor Xa, have been shown to be as effective as and safer than traditional anticoagulation for VTE prophylaxis in no-cancer patients. However, related studies that focused on the anticoagulation in cancer patients are lacked, and almost no net clinical benefit (NCB) analyses that quantified both VTE events and bleeding events have been addressed in this fragile population. Therefore, we aim to investigate this issue using a systematic review and NCB analysis. A comprehensive search of Medline, Embase, and Cochrane Library were performed for randomized controlled trials (RCTs) that reported the VTE events and major bleeding of NOACs and traditional anticoagulants in patients with or without cancer. Odds ratios (ORs) and 95% confidence intervals (CIs) of VTE and bleeding events were calculated using a random-effects model. The primacy outcome of narrow NCB was calculated by pooling ORs of VTE and major bleeding, with a weighting of 1.0. Similarly, the broad NCB was calculated by pooling ORs of VTE and clinically relevant bleeding. Heterogeneity was assessed through I² test and Q statistic, and subgroup analyses were performed on the basis of different patients (VTE patients or acutely ill patients), comparators (vitamin-K antagonists or low-molecular-weight heparin), and follow-up duration (≤6 months or >6 months). Overall, 9 RCTs including 41,454 patients were enrolled, of which 2,902 (7%) were cancer patients, and 38,552 (93%) were no-cancer patients; 20,712 (50%) were administrated with NOACs and 20,742 (50%) were administrated with traditional anticoagulants. The use of NOACs had a superior NCB than traditional anticoagulation in both cancer patients (OR: 0.68, 95%CI: 0.50-0.85 for narrow NCB; OR: 0.76, 95%CI: 0.61–0.91 for broad NCB) and no-cancer patients (OR: 0.75, 95%CI: 0.54-0.96 for narrow NCB; OR: 0.85, 95%CI: 0.67–1.04 for broad NCB), with the estimates mainly from VTE patients receiving long-term warfarin treatment. In conclusion, NOACs may represent a better NCB property compared to traditional anticoagulants in cancer patients who need long-term anticoagulation treatment.

A Focus on Macitentan in the Treatment of Pulmonary Arterial Hypertension

The approval of macitentan has increased the number of pharmacological treatments of pulmonary arterial hypertension (PAH). Here, we review the effect on PAH of macitentan compared to other endothelin receptor antagonists. Drugs targeting the endothelin (ET) pathway include the selective ET_A receptor antagonist ambrisentan, the ET_A /ET_B receptor antagonists, bosentan and macitentan, which were recently approved for PAH treatment. Macitentan exhibits higher antagonistic potency than bosentan and ambrisentan in pulmonary smooth muscle cells. Compared to ambrisentan and bosentan, macitentan has a longer duration of action, reflected by the longer half-life, as well as pharmacodynamics attributed to its active metabolite, ACT-132577. The efficacy of macitentan on PAH was investigated in the phase III SERAPHIN trial (NCT00660179). Macitentan significantly reduced morbidity and mortality. It improved the 6-min. walk distance (6MWD) among PAH patients. In the AMB-320/321-E (NCT00578786) study, ambrisentan improved exercise capacity. In the EARLY study (NCT00091715), bosentan showed improvements in 6MWD which were not statistically significant. Bosentan had an effect on PAH in patients with Eisenmenger syndrome (ES) in the BREATHE-5 study (NCT00367770), while macitentan did not improve 6MWD in these patients, but there are differences regarding study size and functional class, and that 30% of the patients treated with macitentan were already in treatment with a phosphodiesterase type 5 inhibitor. Macitentan revealed a lower risk of developing peripheral oedema and hepatotoxicity in the SERAPHIN study. In summary, macitentan has an efficiency comparable to bosentan and ambrisentan in the treatment of PAH. Patients treated with macitentan exhibited less adverse effects compared to bosentan and ambrisentan. In patients with PAH associated with ES, the trials with bosentan and macitentan do not seem comparable, and it needs to be clarified whether these drugs are effective when administered as part of a combination treatment in this condition.

Efficacy and safety of CYP2C19 genotype in stroke or transient ischemic attack patients treated with clopidogrel monotherapy or clopidogrel plus aspirin: Protocol for a systemic review and meta-analysis

BACKGROUND

The relationship of CYP2C19 genotype and clinical efficacy in stroke or transient ischemic attack (TIA) patients treated with clopidogrel monotherapy or clopidogrel plus aspirin remains unknown. We thus aim to conduct a meta-analysis to appraise evidence on the association of CYP2C19 genotype and clinical efficacy for stroke or TIA.

METHODS

An electronic search will be performed for clinical trials that reported the interested efficacy data (stroke, myocardial infarction, or vascular death) and safety data (any bleeding) in clopigogrel-treated patients with stroke or TIA. Odds ratios (ORs) with their confidence intervals (CIs) will be calculated using a meta-analysis.

RESULTS

This study will provide the evidence of the relationship between CYP2C19 genotype and clinical efficacy and safety in stroke/TIA patients taking clopidogrel by pooling the results of individual studies.

CONCLUSIONS

The results will bring about vigorous evidence in this issue and guide both clinical decision-making and future research.

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.

Update on Endothelin Receptor Antagonists in Hypertension

PURPOSE OF REVIEW

To review the most recent data on the development of endothelin receptor antagonists (ERAs) for the treatment of hypertension and the management of diabetic nephropathy RECENT FINDINGS: Recent reviews and meta-analyses of experimental and clinical data obtained with ERAs confirmed that endothelin receptor blockade is associated with significant decreases in blood pressure in essential hypertension but also in resistant hypertension. In addition, in patients with diabetic nephropathy, ERAs induce significant 30-40% decreases in albuminuria when administered on top of blockers of the renin-angiotensin system. Yet, the benefits of ERAs have often been limited by their tolerability profile, essentially fluid retention and the development of edema and liver toxicity. Hence, several programs have been interrupted. Today, only one ERA, aprocitentan, is still under development for the treatment of resistant hypertension. Regarding the place of ERAs in the management of diabetic nephropathy, the results of the SONAR trial with atrasentan are eagerly awaited but the recent interruption of this trial because of insufficient events is worrisome, as one might not obtain all the expected information for this major trial. Blockade of endothelin receptor have a high potential in the treatment of hypertension and the prevention of the progression of renal diseases such as diabetic nephropathy. Today, the number of clinical programs investigating the potential benefits of ERAs is limited and more data must be obtained to define the real place of ERAs in these indications.

Non-vitamin K Antagonist Oral Anticoagulants vs. Warfarin at Risk of Fractures: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Warfarin is a traditional oral anticoagulant for preventing thrombotic events in patients with atrial fibrillation (AF) and venous thromboembolism. Along with the widespread clinical use, the potential association between warfarin use and fracture risk have been addressed gradually. Non-vitamin K antagonist oral anticoagulants (NOACs), targeting thrombin or Xa factor, have been recommended as an optimal alternative due to their favorable property of thromboembolism prophylaxis and reduced bleeding risk. However, evidence of the fracture risk with NOACs use is limited. Therefore, the present study investigated this issue by a meta-analysis. Medline, Embase, Cochrane Library and the ClinicalTrials.gov Website were searched for randomized controlled trials (RCTs) that reported the fracture data of NOACs and warfarin. The primacy outcome was a composite of any fracture. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models according to between-study heterogeneity. Heterogeneity was assessed through I² test and Q statistic, and the number of patients needed to treat (NNT) was calculated based on fracture incidence. Subgroup analyses were conducted according to individual NOACs, indications, and duration of follow up. Finally, 12 RCTs involving 89,549 patients were included, among which 44,816 (50%) receiving NOACs and 44,733 (50%) receiving warfarin. Overall, 1,139 (1.3%) patients including 515 NOACs users (1.1%) and 624 warfarin users (1.4%) developed fracture. Risk of fracture was significantly lower in NOACs compared to warfarin (RR: 0.82, 95%CI: 0.73–0.93, P = 0.001), with a NNT of 333. No significantly decreased risk was detected according to fracture sites. Subgroup analysis confirmed that the estimate of decreased fracture risk was derived mainly from AF patients receiving long-term anticoagulation treatment. The meta-regression did not detect any potential confounding on fracture risk. No heterogeneity between the studies (I² = 15.0%) and no publication bias was identified. In conclusion, the use of NOACs was associated with a lower risk of fracture compared to warfarin, but with a relatively low absolute risk reduction. Therefore, screening for the fracture risk should be considered before initiating anticoagulation treatment. For patients who are at high risk of fracture or expected long-term treatment of anticoagulation, NOACs may represent a preferable alternative to warfarin.

Pulmonary arterial hypertension: pathogenesis and clinical management

Pulmonary hypertension is defined as a resting mean pulmonary artery pressure of 25 mm Hg or above. This review deals with pulmonary arterial hypertension (PAH), a type of pulmonary hypertension that primarily affects the pulmonary vasculature. In PAH, the pulmonary vasculature is dynamically obstructed by vasoconstriction, structurally obstructed by adverse vascular remodeling, and pathologically non-compliant as a result of vascular fibrosis and stiffening. Many cell types are abnormal in PAH, including vascular cells (endothelial cells, smooth muscle cells, and fibroblasts) and inflammatory cells. Progress has been made in identifying the causes of PAH and approving new drug therapies. A cancer-like increase in cell proliferation and resistance to apoptosis reflects acquired abnormalities of mitochondrial metabolism and dynamics. Mutations in the type II bone morphogenetic protein receptor (BMPR2) gene dramatically increase the risk of developing heritable PAH. Epigenetic dysregulation of DNA methylation, histone acetylation, and microRNAs also contributes to disease pathogenesis. Aberrant bone morphogenetic protein signaling and epigenetic dysregulation in PAH promote cell proliferation in part through induction of a Warburg mitochondrial-metabolic state of uncoupled glycolysis. Complex changes in cytokines (interleukins and tumor necrosis factor), cellular immunity (T lymphocytes, natural killer cells, macrophages), and autoantibodies suggest that PAH is, in part, an autoimmune, inflammatory disease. Obstructive pulmonary vascular remodeling in PAH increases right ventricular afterload causing right ventricular hypertrophy. In some patients, maladaptive changes in the right ventricle, including ischemia and fibrosis, reduce right ventricular function and cause right ventricular failure. Patients with PAH have dyspnea, reduced exercise capacity, exertional syncope, and premature death from right ventricular failure. PAH targeted therapies (prostaglandins, phosphodiesterase-5 inhibitors, endothelin receptor antagonists, and soluble guanylate cyclase stimulators), used alone or in combination, improve functional capacity and hemodynamics and reduce hospital admissions. However, these vasodilators do not target key features of PAH pathogenesis and have not been shown to reduce mortality, which remains about 50% at five years. This review summarizes the epidemiology, pathogenesis, diagnosis, and treatment of PAH.

The safety of endothelin receptor antagonists in the treatment of pulmonary arterial hypertension: Protocol for a systemic review and network meta-analysis

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive disease and ultimately leads to right heart failure. Endothelin receptor antagonists (ERAs) have been demonstrated to significantly improve prognosis in PAH. However, ERAs-induced side effects can result in poor patient tolerance. Thus, we aim to evaluate current safety evidence of ERAs in PAH.

METHODS

An electronic search will be performed for randomized controlled trials (RCTs) that reported the interested safety data (abnormal liver function, peripheral edema, and anemia) of ERAs in PAH. Risk ratios (RRs) with their confidence intervals (CIs) and the surface under the cumulative ranking curve (SUCRA) will be calculated using a network analysis.

RESULTS

This study will provide the safety evidence of ERAs in PAH by combining the results of individual studies based on direct- and network comparison, and to rank ERAs in the evidence network.

CONCLUSIONS

The results will supplement missing evidence of head-to-head comparisons between different ERAs and guide both clinical decision-making and future research.

Managing the Patient With Pulmonary Arterial Hypertension and Methamphetamine Use: A Practical Perspective for the Clinician

Pulmonary arterial hypertension (PAH) is a serious, chronic, progressive cardiopulmonary disease. PAH is associated with several concomitant conditions, as well as drugs and toxins.12 Methamphetamine abuse is likely associated with the development of PAH.3 Methamphetamine abuse is epidemic in the United States and abroad, with rates of new users escalating since 2012. There are over 100,000 new users annually as young as 12 years old. Treating a patient with a history of methamphetamine abuse poses many challenges for a clinician, including nonadherence, therapeutic treatment selection, complex psychosocial issues, and relapse or continued drug abuse. Patients with methamphetamine-associated PAH (Meth-APAH) have higher mortality rates when compared to idiopathic PAH.3 Having a better understanding of the complexities of addiction and working with a multidisciplinary team that includes a social worker to provide care and counseling to these patients can improve their trajectory. In this article, we will offer insight and background into methamphetamine abuse and addiction, as well as discuss a practical approach for clinicians in treating a patient with Meth-APAH, based on the literature, as well as our personal experiences at University of California, San Francisco Medical Center.

Incidence and risk of respiratory tract infection associated with specific drug therapy in pulmonary arterial hypertension: a systematic review

Specific drug therapy has been proven to improve functional capacity and slow disease progression in pulmonary arterial hypertension (PAH), regretfully with the data on the risk of respiratory tract infection (RTI) associated with specific drug therapy being limited. Databases of Medline, Embase, Cochrane Library and the ClinicalTrials.gov Website were searched for randomized controlled trials (RCTs) that reported the RTI data of PAH-specific drug therapy in patients. The primacy outcome was assessed by employing a fixed-effects model. Totally, 24 trials involving 6307 patients were included in the analysis. PAH-specific drug therapy was not significantly associated with the increased risk of both RTI (19.4% vs. 21.1% RR 1.02, 95%CI 0.92-1.14, P = 0.69) and serious RTI (4.3% vs. 5.0% RR 0.99, 95%CI 0.77-1.26, P = 0.93) compared to placebo. The results were consistent across the key subgroups. No heterogeneity between the studies (I2 = 35.8% for RTI, and I2 = 0.0% for serious RTI) and no publication bias was identified. In conclusion, no significant increase in RTI had been found in PAH-specific drug therapy when compared with placebo. Whereas, RTI in PAH patients is still worthy of clinical attention.

Relationship Between Atrasentan Concentrations and Urinary Albumin to Creatinine Ratio in Western and Japanese Patients With Diabetic Nephropathy

PURPOSE

The objective of the current analyses was to characterize the pharmacokinetic properties of atrasentan and the exposure-response relationships for the efficacy end point, urinary albumin to creatinine ratio (UACR), and the treatment-emergent adverse event, peripheral edema, during 8 or 12 weeks of treatment.

METHODS

Results from 3 Phase II, randomized, double-blind, placebo-controlled studies (N = 257) were used for the population pharmacokinetic and exposure-response models. Concentration-time and response data for efficacy and tolerability were analyzed using a nonlinear mixed-effects population analysis and logistic regression approaches.

FINDINGS

The pharmacokinetic data were adequately described by a 2-compartment model with first-order absorption and elimination. After weight was accounted for, no clinically meaningful differences were found in CL/F or V_d/F of the central compartment between Western and Japanese patients. Exposure-response analyses confirmed the efficacy of atrasentan in reducing UACR, with an estimated decrease in UACR of ≥37% when the atrasentan dose was 0.75 mg or higher. No significant association between atrasentan exposure and the rate of edema was identified at atrasentan doses of 0.5, 0.75, and 1.25 mg. The rates of peripheral edema were comparable in patients receiving active treatment and placebo.

IMPLICATIONS

The exposure-response relationships for efficacy and tolerability were consistent between Western and Japanese patients. On the basis of these analyses, a dose of 0.75 mg/d was selected for the Phase III trial. ClinicalTrials.gov identifiers: NCT01356849, NCT01399580, and NCT01424319.

Complex Pathophysiology of Pulmonary Hypertension Associated with Systemic Sclerosis: Potential Unfavorable Effects of Vasodilators

Therapeutic advance by pulmonary vasodilators has provided huge impacts on prognosis in patients with pulmonary arterial hypertension (PAH), but outcomes of systemic sclerosis (SSc)-associated PAH still remain unsatisfactory. One of the major reasons is a series of potential unfavorable effects triggered by pulmonary vasodilators, which result from the complex pathophysiology of SSc-PAH. We herein present and discuss five representative conditions potentially induced by pulmonary vasodilators, including (i) emergence of latent pulmonary veno-occlusive disease, (ii) emergence of latent left-heart disease, (iii) worsening of pulmonary gas change in the presence of interstitial lung disease, (iv) ischemic limb gangrene by stealing of blood flow, and (v) uncontrolled hemorrhage from gastrointestinal telangiectasia. The former three conditions are common causes for worsening of dyspnea or oxygenation during treatment with pulmonary vasodilators, whereas the latter two are rare, but have significant negative impacts on patients’ quality of life and survival. These unfavorable conditions are pitfalls in clinical practice, and interfere with optimizing therapies in patients with SSc-PAH. Therefore, pre-assessment of pathophysiology of pulmonary hypertension and cautious monitoring during the treatment are necessary to achieve better outcomes in patients with SSc-PAH.