Macitentan in Pulmonary Arterial Hypertension Associated with Connective Tissue Disease (CTD-PAH): Real-World Evidence from the Combined OPUS/OrPHeUS Dataset

INTRODUCTION

Data on real-world clinical practice and outcomes of patients with pulmonary arterial hypertension associated with connective tissue disease (CTD-PAH) are scarce. The OPUS/OrPHeUS studies enrolled patients newly initiating macitentan, including those with CTD-PAH. This analysis describes patient characteristics, treatment patterns, outcomes, and safety profiles of patients with CTD-PAH newly initiating macitentan in the US using the OPUS/OrPHeUS combined dataset.

METHODS

OPUS was a prospective, US, multicenter, long-term, observational drug registry (April 2014-June 2020). OrPHeUS was a retrospective, US, multicenter medical chart review (October 2013-March 2017). The characteristics, treatment patterns, safety, and outcomes during macitentan treatment of patients with CTD-PAH and its subgroups systemic sclerosis (SSc-PAH), systemic lupus erythematosus (SLE-PAH), and mixed CTD (MCTD-PAH) were descriptively compared to patients with idiopathic/heritable PAH (I/HPAH).

RESULTS

The combined OPUS/OrPHeUS population included 2498 patients with I/HPAH and 1192 patients with CTD-PAH (708 SSc-PAH; 159 SLE-PAH; 124 MCTD-PAH, and 201 other CTD-PAH etiologies). At macitentan initiation for patients with I/HPAH and CTD-PAH, respectively: 61.2 and 69.3% were in World Health Organization functional class (WHO FC) III/IV; median 6-min walk distance was 289 and 279 m; and 58.1 and 65.2% received macitentan as combination therapy. During follow-up, for patients with I/HPAH and CTD-PAH, respectively: median duration of macitentan exposure observed was 14.0 and 15.8 months; 79.0 and 83.0% experienced an adverse event; Kaplan-Meier estimates (95% confidence limits [CL]) of patients free from all-cause hospitalization at 1 year were 60.3% (58.1, 62.4) and 59.3% (56.1, 62.3); and Kaplan-Meier estimates (95% CL) of survival at 1 year were 90.5% (89.1, 91.7) and 90.6% (88.6, 92.3).

CONCLUSIONS

Macitentan was used in clinical practice in patients with CTD-PAH and its subgroups, including as combination therapy. The safety and tolerability profile of macitentan in patients with CTD-PAH was comparable to that of patients with I/HPAH.

TRIAL REGISTRATION

OPsumit® Users Registry (OPUS): NCT02126943; Opsumit® Historical Users cohort (OrPHeUS): NCT03197688; www.

CLINICALTRIALS

gov Graphical abstract available for this article.

Stability Indicating RP-HPLC-DAD method for simultaneous estimation of tadalafil and macitentan in synthetic mixture for treatment of pulmonary arterial hypertension

OBJECTIVE

High Performance liquid chromatography is an integral analytical tool in assessing drug product stability. A simple, selective, precise, accurate and stability indicating RP-HPLC method was developed and validated for analysis of Tadalafil and Macitentan in synthetic mixture.

MATERIAL AND METHOD

Chromatographic separation was performed using Phenomex Gemini C18 (25cm×4.6nm, 5μm) Column. The mobile phase consists of (10mM Ammonium Acetate in water and [Methanol: ACN 20: 80% v/v]) (40: 60% v/v). The flow rate was set to be 1.0mL/min. The injection volume was 10.00μL. The detection was carried out at 260nm at column temperature 35°C.

RESULTS

The method was validating according to ICH Q2R1 guideline for accuracy, precision, reproducibility, specificity, robustness and detection and quantification limits. Stability testing was performed on Tadalafil and Macitentan and it was found that these degraded sufficiently in all applied chemical and physical conditions. Linearity for Tadalafil and Macitentan was observed 0.4-100μg/mL and 0.1-25μg/mL with correlation coefficient at 0.9999. LOD and LOQ 0.008μg/mL and 0.024μg/mL and 0.001μg/mL and 0.0029μg/mL for Tadalafil and Macitentan respectively.

CONCLUSION

The developed RP-HPLC method was found to be suitable for the determination of both the drugs.

Differential inhibition of sildenafil and macitentan on saxagliptin metabolism

The development of diabetes mellitus (DM) is generally accompanied by erectile dysfunction (ED) and pulmonary arterial hypertension (PAH), which increases the use of combination drug therapy and the risk of drug-drug interactions. Saxagliptin for the treatment of DM, sildenafil for the treatment of ED and PAH, and macitentan for the treatment of PAH are all substrates of CYP3A4, which indicates their potential involvement in drug-drug interactions. Therefore, we investigated potential pharmacokinetic interactions between saxagliptin and sildenafil/macitentan. We investigated this speculation both in vitro and in vivo, and explored the underlying mechanism using in vitro hepatic metabolic models and molecular docking assays. The results showed that sildenafil substantially inhibited the metabolism of saxagliptin by occupying the catalytic site of CYP3A4 in a competitive manner, leading to the alterations in the pharmacokinetic properties of saxagliptin in terms of increased maximum plasma concentration (Cmax), area under the plasma concentration-time curve from time 0 to 24 h (AUC(0-t)), area under the plasma concentration-time curve from time 0 extrapolated to infinite time (AUC(0-∞)), decreased clearance rate (CLz/F), and prolonged terminal half-life (t1/2). In contrast, a slight inhibition was observed in saxagliptin metabolism when concomitantly used with macitentan, as no pharmacokinetic parameters were altered, except for CLz/F. Thus, dosage adjustment of saxagliptin may be required in combination with sildenafil to achieve safe therapeutic plasma concentrations and reduce the risk of potential toxicity, but it is not necessary for co-administration with macitentan.

Effect of Macitentan in Pulmonary Arterial Hypertension and the Relationship Between Echocardiography and cMRI Variables: REPAIR Echocardiography Sub-study Results

INTRODUCTION

The aim of this sub-study was to evaluate the relationship between echocardiography (echo) and cardiac magnetic resonance imaging (cMRI) variables and to utilize echo to assess the effect of macitentan on right ventricle (RV) structure and function.

METHODS

REPAIR (NCT02310672) was a prospective, multicenter, single-arm, open-label, 52-week, phase 4 study in pulmonary arterial hypertension (PAH) patients, which investigated the effect of macitentan 10 mg as monotherapy, or in combination with a phosphodiesterase 5 inhibitor, on RV structure, function, and hemodynamics using cMRI and right heart catheterization. In this sub-study, patients were also assessed by echo at screening and at weeks 26 and/or 52. Post hoc correlation analyses between echo and cMRI variables were performed using Pearson's correlation coefficient, Spearman's correlation coefficient, and Bland-Altman analyses.

RESULTS

The Echo sub-study included 45 patients. Improvements in echo-assessed RV stroke volume (RVSV), left ventricular SV (LVSV), LV end-diastolic volume (LVEDV), RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), and in 2D global longitudinal RV strain (2D GLRVS) were observed at weeks 26 and 52 compared to baseline. There was a strong correlation between echo (LVSV, 2D GLRVS, and LVEDV) and cMRI variables, with a moderate correlation for RVSV. Bland-Altman analyses showed a good agreement for LVSV measured by echo versus cMRI, whereas an overestimation in echo-assessed RVSV was observed compared to cMRI (bias of - 15 mL). Hemodynamic and functional variables, as well as safety, were comparable between the Echo sub-study and REPAIR.

CONCLUSIONS

A good relationship between relevant echo and cMRI parameters was shown. Improvements in RV structure and function with macitentan treatment was observed by echo, consistent with results observed by cMRI in the primary analysis of the REPAIR study. Echo is a valuable complementary method to cMRI, with the potential to non-invasively monitor treatment response at follow-up.

TRIAL REGISTRATION NUMBER

REPAIR NCT02310672.

Safety of Macitentan for the Treatment of Portopulmonary Hypertension: Real-World Evidence from the Combined OPUS/OrPHeUS Studies

INTRODUCTION

Portopulmonary hypertension (PoPH) carries a worse prognosis than other forms of pulmonary arterial hypertension (PAH). Data regarding use of PAH-specific therapies in patients with PoPH are sparse as they are usually excluded from clinical trials. This analysis describes patient characteristics, treatment patterns, outcomes, and safety profiles in patients with PoPH newly initiating macitentan in the USA using the OPUS/OrPHeUS combined dataset.

METHODS

OPUS was a prospective, US, multicenter, observational drug registry (April 2014-June 2020); OrPHeUS was a retrospective, US, multicenter chart review (October 2013-March 2017). Additional information regarding patients' liver disease was retrospectively collected for patients with PoPH in OPUS.

RESULTS

The OPUS/OrPHeUS dataset included 206 patients with PoPH (median age 58 years; 52.4% female), with baseline cirrhosis and liver test abnormalities reported in 72.8% and 31.6% of patients respectively. Macitentan was initiated as combination therapy in 74.8% of patients and median (Q1, Q3) exposure to macitentan was 11.9 (3.1, 26.0) months. One-year Kaplan-Meier estimates (95% confidence limit, CL) of patients free from all-cause hospitalization and survival were 48.6% (40.7, 56.0) and 82.2% (75.1, 87.4). Of the 96 patients with PoPH in OPUS, 29.2% were classified as in need of liver transplant due to underlying liver disease during the study; transplant waitlist registration was precluded because of PAH severity for 32.1% and 17.9% were transplanted. Hepatic adverse events (HAE) were experienced by 49.0% of patients; the most common being increased bilirubin (16.0%), ascites (7.3%), and hepatic encephalopathy (5.8%); 1.5% and 21.8% of patients discontinued macitentan as a result of HAE and non-hepatic adverse events.

CONCLUSION

There were no unexpected safety findings in patients with PoPH treated with macitentan. These data add to the evidence supporting the safety and tolerability of macitentan in patients with PoPH. A graphical abstract is available with this article.

TRIAL REGISTRATION

OPsumit® Users Registry (OPUS): NCT02126943; OPsumit® Historical Users cohort (OrPHeUS): NCT03197688; www.

CLINICALTRIALS

gov .

Efficacy and safety of the endothelin-1 receptor antagonist macitentan in epicardial and microvascular vasospasm; a proof-of-concept study

Background

Treatment of patients diagnosed with angina due to epicardial or microvascular coronary artery spasm (CAS) is challenging because patients often remain symptomatic despite conventional pharmacological therapy. In this prospective, randomized, double-blind, placebo-controlled, sequential cross-over proof-of-concept study, we compared the efficacy and safety of macitentan, a potent inhibitor of the endothelin-1 receptor, to placebo in symptomatic patients with CAS despite background pharmacological treatment.

Methods

Patients with CAS diagnosed by invasive spasm provocation testing with >3 anginal attacks per week despite pharmacological treatment were considered for participation. Participants received either 10 mg of macitentan or placebo daily for 28 days as add-on treatment. After a wash-out period patients were crossed over to the alternate treatment arm. The primary endpoint was the difference in anginal burden calculated as [1] the duration (in minutes) * severity (on a Visual Analogue Scale (VAS) pain scale 1-10); and [2] the frequency of angina attacks * severity during medication use compared to the run-in phase.

Results

28 patients of whom 22 females (79%) and a mean age of 55.3 ± 7.6 completed the entire study protocol (epicardial CAS n = 19 (68), microvascular CAS n = 9 (32)). Change in both indices of anginal burden were not different during treatment with add-on macitentan as compared to add-on placebo (duration*severity: -9 [-134 78] vs -45 [-353 11], p = 0.136 and frequency*severity: -1.7 [-5.8 1.2] vs -1.8 [-6.2 0.3], p = 0.767). The occurrence and nature of self-reported adverse events were closely similar between the treatment phase with macitentan and placebo.

Conclusion

In patients with angina due to epicardial or microvascular CAS despite background pharmacological treatment, 28 days of add-on treatment with the ET-1 receptor antagonist, macitentan 10 mg daily, did not reduce anginal burden compared to add-on treatment with placebo.Trial Registrationhttps://trialsearch.who.int/, Identifier: EUCTR2018-002623-42-NL. Registration date: 20 February 2019.

Macitentan treatment of portopulmonary hypertension with hepatopulmonary syndrome: a case report and literature review

Pulmonary arterial hypertension-targeted therapies in portopulmonary hypertension (PoPH) are scarce, let alone for patients with chronic liver failure (CLF) and hepatopulmonary syndrome (HPS). A 48-year male was admitted to the hospital because of cirrhosis for 18 years, systemic oedema, and chest distress after exercise for 1 week. He was diagnosed with CLF, PoPH, and HPS. After 7 weeks of macitentan treatment, the patient's activity tolerance, pulmonary artery systolic pressure, arterial partial pressure of oxygen (PaO₂ ), cTNI, and NT-proBNP changes indicated gradual recovery, without hepatic safety concerns. This case indicated that administering macitentan in patients diagnosed as PoPH (with CLF and HPS) may be efficient and safe enough in a clinical setting.

Adjusting Overall Survival Estimates of Macitentan in Pulmonary Arterial Hypertension After Treatment Switching: Results from the SERAPHIN Study

Introduction

Evaluating overall survival in randomized controlled trials (RCTs) can often be confounded by bias introduced by treatment switching. SERAPHIN was a large RCT that evaluated the effects of long-term treatment with the endothelin receptor antagonist macitentan in patients with pulmonary arterial hypertension. In an intent-to-treat (ITT) analysis, a non-significant decrease in the risk of all-cause mortality up to study closure was reported with macitentan 10 mg versus placebo. As patients could switch treatment when experiencing symptoms of disease progression, this analysis attempts to adjust for the confounding effects on overall survival.

Methods

The inverse probability of censoring weighted (IPCW) and rank-preserving structural failure time (RPSFT) models were used to estimate the treatment effect on overall mortality had there been no treatment switching in SERAPHIN. Time to all-cause death was evaluated up to study closure. Treatment switching was defined as patients in the placebo group switching to open-label macitentan 10 mg, and patients in the macitentan 10 mg group prematurely discontinuing macitentan.

Results

By study closure, 73.2% (183/250) of patients in the placebo group had switched to macitentan 10 mg. Among these patients, exposure time to macitentan 10 mg represented 28.2% of total study treatment exposure (cumulative exposure 134.6 patient-years). At study closure, 24.8% (60/242) of patients in the macitentan 10 mg group were not receiving open-label macitentan; mean time not receiving macitentan was 44.3 weeks. The adjusted hazard ratios (HR) for overall survival using the IPCW and RPSFT methods were lower (HR 0.42, 95% confidence interval [CI] 0.22, 0.81; p = 0.009, and HR 0.33, 95% CI 0.04, 2.83, respectively) than the ITT unadjusted HR (0.80, 95% CI 0.51, 1.24).

Conclusion

These results from the current analyses indicate that in SERAPHIN, the standard ITT analysis was confounded by treatment switching resulting in an underestimation of the benefit of macitentan 10 mg on overall survival. By adjusting for switching, the IPCW and RPSFT models estimated a 58% and 67% reduction in risk of mortality, respectively, with macitentan 10 mg versus placebo.

Trial registration

ClinicalTrials.gov identifier: NCT00660179.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02253-8.

Long-Term Safety, Tolerability and Survival in Patients with Pulmonary Arterial Hypertension Treated with Macitentan: Results from the SERAPHIN Open-Label Extension

Introduction

In SERAPHIN, a long-term, event-driven, double-blind randomised controlled trial in pulmonary arterial hypertension (PAH), macitentan 10 mg significantly reduced the risk of morbidity/mortality compared with placebo. Its open-label extension study (SERAPHIN OL) further assessed long-term safety and tolerability of macitentan 10 mg in PAH patients.

Methods

Patients in SERAPHIN who completed the double-blind treatment period or experienced a morbidity event during the study could enter SERAPHIN OL. Patients received macitentan 10 mg once daily, and safety and survival were assessed until end of treatment (+ 28 days). Two overlapping sets were analysed for safety: (1) all patients in SERAPHIN OL (OL safety set); (2) patients randomised to macitentan 10 mg in SERAPHIN (long-term safety/survival set). Survival was evaluated as an exploratory endpoint in the latter set.

Results

Of 742 patients randomised in SERAPHIN, 550 (74.1%) entered SERAPHIN OL (OL safety set); 242 patients were randomised to macitentan 10 mg in SERAPHIN (long-term safety/survival set). Median (min, max) exposure to macitentan 10 mg was 40.1 (0.1, 130.5) months (2074.7 patient-years; OL safety set) and 54.7 (0.1, 141.3) months (1151.0 patient-years; long-term safety/survival set). Safety in both analysis sets was comparable to the known safety profile of macitentan. Kaplan-Meier survival estimates (95% CI) at 1, 5, 7 and 9 years were 95.0% (91.3, 97.1), 73.3% (66.6, 78.9), 62.6% (54.6, 69.6) and 52.7% (43.6, 61.0), respectively (long-term safety/survival set; median follow-up: 5.9 years).

Conclusions

This analysis provides the longest follow-up for safety and survival published to date for any PAH therapy. The safety profile of macitentan 10 mg over this extensive treatment period was in line with that observed in SERAPHIN. As the majority of patients were receiving other PAH therapy at macitentan initiation, our study provides additional insight into the long-term safety of macitentan, including as part of combination therapy.

Trial Registration

ClinicalTrials.gov Identifiers: NCT00660179 and NCT00667823.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02199-x.

Management and control of intraocular pressure applying macitentan hydrogel film formulation: improved effect of surfactant and cosurfactant system

BACKGROUND

Macitentan blocks endothelin receptors in order to control the pulmonary arterial hypertension (PAH). Oral administration of macitentan is associated with painful urination and troubled breathing.

OBJECTIVES

Formulated macitentan hydrogel film was used for examining the control of intraocular pressure, and the effect of surfactant and cosurfactant was studied.

METHODS

Macitentan ocular film formulation has been prepared in hydroxypropyl methylcellulose (HPMC) matrix system using different surfactant/co-surfactant system, and intraocular pressure was monitored on normotensive rabbit eyes after application in the cul-de-sac.

RESULTS

The solid state characterization of the film indicated amorphisation of macitentan and no issues regarding major incompatibility was observed. Combination of surfactant, co-surfactant and hydrophilic co-solvent systems in the said films markedly improved the drug release and mucosal tissue permeation. Presence of PEG and Transcutol significantly improved ex vivo corneal permeation of MP and MT respectively compared to other films. Transcutol (MT) exhibited greatest difference among the formulations by improving the vesicular bilayer fluidity and reducing the mucosal tissue barrier facilitating the transcorneal diffusion. A combination of diffusion and erosion control behavior was observed in drug release and corneal permeation of the films due to the balanced liquid penetration and polymeric chain relaxation rate. MP and MT films were used for further in vivo studies to achieve possible effective and prolonged control of intraocular pressure. In vivo study has revealed the reduction in intraocular pressure upto about 23 % when tested on normotensive rabbit model. The films has managed to lower the IOP upto 3 h.

CONCLUSION

Developed macitentan hydrogel film containing Transcutol (MT) could have a high potential for the control and management of ocular hypertension after topical application.

Results of Macitentan in Japanese Patients With Chronic Thromboembolic Pulmonary Hypertension - A Prospective, Multicenter, Open-Label, Single-Arm, Phase 3 Study

Background: Macitentan, an endothelin-receptor antagonist, is approved in Japan for the treatment of pulmonary arterial hypertension (PAH). This study evaluated the use of macitentan for chronic thromboembolic pulmonary hypertension (CTEPH) in Japanese patients. Methods and Results: This open-label single-arm Phase 3 study evaluated the efficacy and safety of oral macitentan 10 mg (once daily) in Japanese CTEPH patients. The study was prematurely discontinued due to the sponsor's decision to not develop macitentan 10 mg further for the indication of CTEPH (unrelated to safety concerns). Of the 9 patients enrolled in the study, 4 completed 24 weeks of treatment. The mean (±SD) ratio of pulmonary vascular resistance (PVR) at Week 16 to baseline was 71.9±34.3%. The mean (±SD) decreases in PVR and the PVR index (PVRI) from baseline to Week 16 were 181.4±243.9 dyn·s/cm5 and 280.6±366.0 dyn·s·m2/cm5, respectively. The mean (±SD) increase in the 6-min walk distance from baseline to Week 24 was 44.3±46.8 m. All treatment-emergent adverse events (TEAEs) were mild or moderate in severity, except for 1 serious TEAE of angioplasty reported in 1/9 patients that was severe in intensity. Conclusions: Definite conclusions regarding the efficacy of macitentan 10 mg in Japanese patients with CTEPH cannot be drawn because of premature study discontinuation. No safety concerns were observed, and the safety profile was consistent with previously reported studies in CTEPH and PAH patients.

Effects of Dual Initial Combination Therapy With Macitentan Plus Riociguat or Macitentan Plus Selexipag on Hemodynamics in Patients With Pulmonary Arterial Hypertension (SETOUCHI-PH Study) - Protocol of a Multicenter Randomized Control Trial

Background: The latest guideline from the European Society of Cardiology and European Respiratory Society recommends initial combination therapy with oral pulmonary arterial hypertension (PAH)-specific drugs in PAH patients with World Health Organization functional class (WHO-FC) II or III. However, whether this initial combination therapy improves hemodynamics and clinical failure events regardless of the combination of PAH-specific drugs remains unknown. This study was designed to evaluate whether the initial combination therapy with macitentan plus riociguat or macitentan plus selexipag showed equal efficacy in reducing pulmonary vascular resistance (PVR) 8 months after administration. Methods and Results: This study is a multicenter randomized control trial. PAH subjects with WHO-FC II or III will be randomized (1 : 1) into initial combination therapy with either macitentan plus riociguat or macitentan plus selexipag, and will be observed 8 months after the initiation of treatment. The primary endpoint will be the difference in the change ratio of PVR from baseline to after 8 months of treatment. Conclusions: The SETOUCHI-PH study will clarify whether initial combination therapy with macitentan plus riociguat or macitentan plus selexipag results in equal reductions in PVR 8 months after administration.

Evaluation of the combination of endothelin receptor antagonists (ERA) and phosphodiesterase-5 inhibitors for the treatment of pulmonary arterial hypertension (PAH) in pathologic human pulmonary arteries in an ex-vivo organ bath model

PURPOSE

Medical combination therapy of pulmonary arterial hypertension (PAH) may alleviate the drawbacks of monotherapy by avoiding drug tolerance and by increasing effectiveness, as shown by the combination of ambrisentan and tadalafil (AMBITION trial). The present ex-vivo study evaluated the combination of the endothelin receptor antagonists (ERA) macitentan and bosentan with the phosphodiesterase-5 (PDE-5) inhibitor vardenafil in pulmonary arteries from patients suffering from terminal lung disease as a model of PAH.

METHODS

Segments of the pulmonary vessels were excised from resected lungs of patients requiring lung transplantation (LTX). Contraction of pulmonary arteries (PA) was elicited by consecutive dose-response curves of endothelin-1 (ET-1) followed by norepinephrine (NE) to allow inhibition by different pathways. Forces were measured isometrically in an organ bath in the presence and absence of ERA and PDE-5 inhibitors and their combination.

RESULTS

PA of 38 patients were examined between October 2016 and November 2019. Bosentan (1E-7 M) and macitentan (1E-8 M, 3E-8 M, 1E-7 M) inhibited ET-1 induced contractions, whereas vardenafil (1E-6 M, 3E-6 M, 1E-5 M) inhibited only the NE induced part of the contractions. Vardenafil enhanced bosentan-induced inhibition of vasoconstriction in a dose-dependent fashion. Combination effects exceeded single bosentan at 3E-6 M and 1E-5 M vardenafil, and they exceeded single vardenafil at the lower vardenafil concentrations. Macitentan showed a more pronounced inhibition than bosentan regardless of the lower concentrations. Accordingly, combination effects with vardenafil resembled those of macitentan alone.

CONCLUSIONS

Macitentan and bosentan were potent antagonists of vasoconstriction in PA of LTX patients. The benefit of drug combinations was demonstrated at selected concentrations only owing to a narrow therapeutic range of vardenafil in this ex-vivo model. These results suggest the utility of drug combinations other than the established pair of ambrisentan and tadalafil in PAH treatment but also make a case for a further assessment of vasodilator properties of drugs complementing ERA.

Incident pulmonary arterial hypertension associated with Bosutinib

Pulmonary arterial hypertension is associated with tyrosine kinase inhibitors used in the treatment of chronic myeloid leukemia. Dasatinib is a known cause of drug-induced pulmonary arterial hypertension. There have been case reports linking Bosutinib with deterioration of pre-existing pulmonary arterial hypertension. Here, we present a case of a 37-year-old woman with chronic myeloid leukemia treated with Bosutinib who was diagnosed with pulmonary arterial hypertension. Prior to Bosutinib, she had received Dasatinib without documented cardiopulmonary toxicity. Withdrawal of Bosutinib led to partial reversal of pulmonary arterial hypertension, and with the addition of pulmonary arterial hypertension-targeted treatment, there was near normalization of hemodynamics.

The Clinical Efficacy of Endothelin Receptor Antagonists in Patients with Pulmonary Arterial Hypertension

Therapeutic strategies for pulmonary arterial hypertension (PAH) have made remarkable progress over the last two decades. Currently, 3 types of drugs can be used to treat PAH; prostacyclins, phosphodiesterase 5 inhibitors, and endothelin receptor antagonists (ERA). In Japan, the first generation ERA bosentan was reimbursed in 2005, following which the 2nd generation ERAs ambrisentan and macitentan were reimbursed in 2009 and 2015, respectively. The efficacy of each ERA on hemodynamics in PAH patients remains to be elucidated. The aims of this study were to evaluate the hemodynamic effects of ERAs and compare these effects among each generation of ERAs.We retrospectively examined the clinical parameters of 42 PAH patients who were prescribed an ERA (15 bosentan, 12 ambrisentan, and 15 macitentan) and who underwent a hemodynamic examination before and after ERA introduction at our institution from January 2007 to July 2019.In a total of 42 patients, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) were significantly decreased and cardiac index was significantly increased after ERA introduction (P < 0.001) and the World Health Organization-Functional class (WHO-Fc) was significantly improved after ERA introduction (P = 0.005). Next, in a comparison between 1st and 2nd generation ERAs, 2nd generation ERAs were found to have brought about greater improvements in hemodynamic parameters (mPAP and PVR. P < 0.01), heart rate, brain natriuretic peptide, arterial oxygen saturation, and mixed venous oxygen saturation than the 1st generation ERA bosentan.We conclude that all ERAs could successfully improve the hemodynamics of PAH patients and that the newer generation ERAs, ambrisentan and macitentan, seemed to be preferable to bosentan.

Long-term real world clinical outcomes of macitentan therapy in chronic thromboembolic pulmonary hypertension

BACKGROUND

Macitentan treatment for chronic thromboembolic pulmonary hypertension (CTEPH) in the routine clinical setting is increasing. However, 'real world' macitentan experience is scarce and is needed to differentiate from controlled clinical trial settings.

OBJECTIVE

We describe our outcomes and clinical 'real world' experience of macitentan mono- and combination therapy with riociguat or sildenafil in CTEPH.

METHODS

We included all consecutive CTEPH patients, either non-operated or with residual PH after pulmonary endarterectomy (PEA), treated with macitentan in the St. Antonius hospital in Nieuwegein, the Netherlands, between 01-2014 and 11-2019. We describe clinical outcomes and adverse events (AEs) until 2 years after macitentan initiation.

RESULTS

In total 73 CTEPH patients on macitentan were included, of which 18 patients were clinically inoperable (n = 7 declined PEA, n = 11 nonacceptable risk-benefit) and 55 had technically inoperable CTEPH (n = 48)/residual PH (n = 7). Clinically inoperable patients (mean age 72.4 ± 10.2 years, 61% female, 28% macitentan monotherapy, observation period 2.0 (1.9-2.0) years) had a survival of 100% and clinical worsening (CW)-free survival of 88% at 2-year follow-up respectively, with a significant increased 6-min walking distance (6MWD). Technically inoperable/residual PH patients (mean age 62.1 ± 14.1 years, 60% female, 27% macitentan monotherapy, observation period 2.0 (1.0-2.0) years) had a 2-year survival and CW-free survival of 86% and 68% respectively, with significant improved 6MWD and NT-proBNP. Nonsevere AEs were reported in 30% of all patients.

CONCLUSION

Macitentan mono- and combination therapy in non-operated CTEPH and residual PH is safe and improves clinical outcomes till 2-year follow-up.

Monocrotaline-induced pulmonary arterial hypertension: Time-course of injury and comparative evaluation of macitentan and Y-27632, a Rho kinase inhibitor

Novel pharmacological approaches are needed to improve outcomes of patients with idiopathic pulmonary hypertension. Rho-associated protein kinase (ROCK) inhibitors have shown beneficial effects in preclinical models of pulmonary arterial hypertension (PAH), because of their role in the regulation of pulmonary artery vasoconstrictor tone and remodeling. We compared a ROCK inhibitor, Y-27632, for the first time with the dual endothelin receptor antagonist, macitentan, in a monocrotaline-induced rat pulmonary hypertension model. Different methods (echocardiography, hemodynamics, histology of right ventricle and pulmonary vessels, and circulating biomarkers) showed consistently that 100 mg/kg daily of Y-27632 and 10 mg/kg daily of macitentan slowed the progression of PAH both at the functional and structural levels. Treatments started on day 14 after monocrotaline injection and lasted 14 days. The findings of all experimental methods show that the selective ROCK inhibitor Y-27632 has more pronounced effects than macitentan, but a major limitation to its use is its marked peripheral vasodilating action.

Bosentan or Macitentan Therapy in Chronic Thromboembolic Pulmonary Hypertension?

OBJECTIVE

Research comparing bosentan and macitentan in chronic thromboembolic pulmonary hypertension (CTEPH) is scarce, although macitentan might have superior pharmacologic properties. We present the first real-world, 2-year follow-up results and compare clinical outcomes of both drugs in CTEPH.

METHODS

All consecutive, technical inoperable or residual CTEPH patients receiving bosentan or macitentan, diagnosed in our multidisciplinary team between January 2003 and January 2019, were included. We report and compare survival, clinical worsening (CW), adverse events, WHO FC, NT-proBNP and 6-min walking test (6MWT) until 2 years after medication initiation.

RESULTS

In total, 112 patients receiving bosentan or macitentan (58% female, mean age 62 ± 14 years, 68% WHO FC III/IV, 51% bosentan) could be included. Mean treatment duration was 1.9 ± 0.4 years for bosentan and 1.2 ± 0.6 years for macitentan. Two-year survival rate was 91% for bosentan and 80% for macitentan (HR mortality macitentan 1.85 [0.56-6.10], p = 0.31). Two-year CW-free survival was 81% and 58%, respectively (HR CW macitentan 2.16 [0.962-4.87], p = 0.06). Right atrial pressure, cardiac output (for mortality alone) and 6MWT lowest saturation were multivariate predictors at baseline. Overall adverse event rates were comparable and WHO FC, NT-proBNP and 6MWT distance improved similar for both drugs till 2-year follow-up.

CONCLUSION

CTEPH patients receiving bosentan or macitentan have improved clinical outcomes till 2-year follow-up, without significant differences in outcomes between both therapies.

Pharmacological characterization of a highly selective Rho kinase (ROCK) inhibitor and its therapeutic effects in experimental pulmonary hypertension

Studies on the role of Rho-associated protein kinase (ROCK) in experimental pulmonary artery hypertension (PAH) relies mainly on the use of pharmacological inhibitors. However, interpreting these data is hampered by the lack of specificity of commonly utilized inhibitors. To fill this gap, we have selected and characterized a novel ROCK inhibitor, Compound 3, previously described in a patent. Inhibitory potency of Compound 3 against enzymatic activity of ROCK-1 and 2 (IC₅₀ = 10 ± 3.1 and 7.8 ± 0.5 nM, respectively) was accompanied by a strong vasodilating effect in phenylephrine pre-contracted isolated rat pulmonary artery rings (IC₅₀ = 51.7 ± 9.1 nM) as well as in aortic rings (IC₅₀ = 45.5 ± 1.1 nM). Compound 3 showed a remarkable selectivity towards ROCK 1 and 2 when tested against a large panel (>400) of human kinases. A partial explanation for its selectivity is provided from docking simulations within ROCK-1. Pharmacokinetic studies showed that Compound 3 is suitable for a twice daily administration without significant accumulation upon repeated dosing. In rats with monocrotaline (MCT)-induced pulmonary hypertension, therapy with Compound 3, (1 and 3 mg/kg, s.c., b.i.d.), started 14 days after induction of the disease, attenuated right ventricle systolic pressure (RVSP) increase. Morphometric histological analysis showed that Compound 3, at both doses, counteracted MCT-induced medial thickening of lung distal arterioles with an effect comparable to macitentan (10 mg/kg, p.o., q.d.). Compound 3 is a potent and highly selective ROCK inhibitor that ameliorates hemodynamic parameters and counteracts pulmonary vascular remodeling in experimental PAH.

Hemodynamic and Histopathologic Benefits of Early Treatment with Macitentan in a Rat Model of Pulmonary Arterial Hypertension

BACKGROUND AND OBJECTIVES

Macitentan (MAC) reduces morbidity and mortality among advanced-stage pulmonary arterial hypertension (PAH) patients. However, data regarding the histopathologic and hemodynamic benefits of MAC treatment at an early stage of PAH is lacking.

METHODS

One week after monocrotaline (MCT) injection, rats were randomly assigned to MAC (n=16), MAC combined with sildenafil (SIL) (MAC+SIL, n=16), or normal saline (MCT, n=16). Twelve sham rats (Sham) were included for comparison. Right ventricular (RV) systolic function was assessed via echocardiography as the RV fractional area change (RV-FAC). An invasive pressure-volume analysis using a Millar conductance catheter was performed 7 weeks after MCT injection. Rats were subsequently euthanized for histopathologic analysis.

RESULTS

RV-right atrial pressure gradient on echocardiography was significantly increased 3 weeks after MCT injection, but was maintained in the Sham. RV-FAC was less deteriorated in the MAC, compared to that in the MCT (44±3% vs. 25±7%, p<0.05), and the co-administration of SIL showed no additional benefit (45±8%, p>0.05 vs. the MAC). On invasive hemodynamic analyses, RV end-systolic (196±78 μL) and end-diastolic volumes (310±86 μL), pulmonary artery systolic pressure (89±7.2 mmHg), and end-systolic pressure-volume relationship (-254±25.1) were significantly worse in the MCT vs. in the MAC (101±45 μL, 235±55 μL, 40±10.5 mmHg, and -145±42.1, respectively) and MAC+SIL (109±47 μL, 242±46 μL, 38±9.2 mmHg, and -151±39.2, respectively) (all p<0.05). However, the MAC and MAC+SIL did not differ (all p>0.05). On histopathology, both RV and lung fibrosis were significantly reduced in the MAC and MAC+SIL vs. in the MCT (all p<0.05); the 2 treatment groups did not differ.

CONCLUSIONS

MAC treatment at an earlier stage significantly attenuated experimental PAH progression hemodynamically and histopathologically.

Macitentan in daily clinical practice: A single centre, 1-year experience

The effectiveness and safety of macitentan, a dual endothelin-receptor antagonist (ERA) approved for the treatment of pulmonary arterial hypertension (PAH), were shown in an extensive clinical trial oriented towards morbidity and mortality events. Our aim was to describe a single centre's experience of the utilization of macitentan in patients with PAH in clinical practice settings. Thirteen patients with different aetiologies and previous PAH treatments were studied. After 12 months of macitentan treatment, 11 patients improved their functional class (FC), all patients improved their 6-minute walk distance (6MWD) test, and 10 patients lowered their NT-proBNP plasma levels. Additionally, cardiac imaging parameters were also improved. No cases resulted in hospitalization, septostomy, transplant or death.

SERAPHIN haemodynamic substudy: the effect of the dual endothelin receptor antagonist macitentan on haemodynamic parameters and NT-proBNP levels and their association with disease progression in patients with pulmonary arterial hypertension

Aims

The effect of macitentan on haemodynamic parameters and NT-proBNP levels was evaluated in pulmonary arterial hypertension (PAH) patients in the SERAPHIN study. Association between these parameters and disease progression, assessed by the primary endpoint (time to first morbidity/mortality event), was explored.

Methods and results

Of the 742 randomized patients, 187 with right heart catheterization at baseline and month 6 participated in a haemodynamic sub-study. Prespecified endpoints included change from baseline to month 6 in cardiac index (CI), right atrial pressure (RAP), mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), mixed-venous oxygen saturation, and NT-proBNP. Exploratory analyses examined associations between CI, RAP, and NT-proBNP and disease progression using the Kaplan-Meier method and Cox regression models. Macitentan improved CI, RAP, mPAP, PVR and NT-proBNP vs. placebo at month 6. Absolute levels of CI, RAP and NT-proBNP at baseline and month 6, but not their changes, were associated with morbidity/mortality events. Patients with CI > 2.5 L/min/m², RAP < 8 mmHg, or NT-proBNP < 750 fmol/ml at month 6 had a lower risk of morbidity/mortality than those not meeting these thresholds (HR 0.49, 95% CL 0.28–0.86; HR 0.72, 95% CL 0.42–1.22; and HR 0.22, 95% CL 0.15–0.33, respectively).

Conclusions

For all treatment groups, baseline and month 6 values of CI, RAP, and NT-proBNP, but not their changes, were associated with morbidity/mortality events, confirming their relevance in predicting disease progression in patients with PAH. By improving those parameters, macitentan increased the likelihood of reaching threshold values associated with lower risk of morbidity/mortality.

Functional estimation of endothelin-1 receptor antagonism by bosentan, macitentan and ambrisentan in human pulmonary and radial arteries in vitro

BACKGROUND

Endothelin receptor antagonists are approved for pulmonary arterial hypertension. Development of selective ET_A-receptor antagonists over mixed or dual receptor antagonists has depended on a range of receptor binding assays, second messenger assays and functional blood vessel assays. This study compared the 3 clinically-approved endothelin receptor antagonists in assays of human isolated pulmonary and radial arteries in vitro.

METHODS

Human isolated pulmonary (i.d. 5.5mm) and human radial (i.d. 3.23mm) artery ring segments were mounted in organ baths for isometric force measurement. Single concentration-contraction curves to endothelin-1 were constructed in the absence or presence of bosentan (1-10µM), macitentan (0.03-0.3µM) or ambrisentan (0.1-1µM).

RESULTS

All 3 endothelin antagonists caused competitive rightward shifts in the endothelin-1 concentration-response curves in both arteries. The Clark plot and analysis gave the following pK_B values: bosentan, pulmonary artery 6.28±0.13 and radial artery 6.04±0.10; macitentan, pulmonary artery 8.02±0.13 and radial artery 7.49±0.08; and ambrisentan, pulmonary artery 7.38±0.13 and radial artery 6.96±0.10.

CONCLUSIONS

Noting the maximum plasma levels attained from recommended oral doses of each antagonist in volunteers, the pK_B findings here show that there would be significant antagonism of endothelin-1 contraction in the pulmonary and radial arteries at therapeutic plasma levels. This functional assay confirms in human tissue that much higher plasma concentrations of endothelin-1 receptor antagonists are required to be effective than those predicted from binding or other biochemical assays.

The use of Macitentan in Fontan circulation: a case report

Background

The Fontan circulation, a result of a palliative procedure in patients with single systemic ventricles, is defined by chronically elevated pulmonary vascular resistance. When traditional heart failure therapies fail, pharmacological agents that reduce pulmonary artery pressures may be used. These include endothelial-receptor antagonists, prostanoids and phosphodiesterase type 5 inhibitors. We report the first use of macitentan, an endothelin-receptor antagonist, in a patient with a Fontan circulation.

Case presentation

We describe the case of a 50 year old female with tricuspid atresia and transposition of the great arteries. Following complex surgery as a child, she subsequently underwent a fenestrated modified atrial pulmonary Fontan operation which was later converted to a total cavopulmonary anastomosis Fontan circulation. Due to failure of various medications to relieve her worsening symptoms, she was commenced on macitentan in April 2016. Few months later, she demonstrated a significant symptomatic improvement and associated increase in her incremental shuttle walking test distance.

Conclusions

Macitentan has slower receptor dissociation kinetics compared to other endothelin-receptor antagonists, leading to enhanced pharmacological activity with promising effects in patients with pulmonary arterial hypertension. The patient we report has shown considerable improvement in exercise capacity following introduction of this medication and thus we suggest further randomised trials to establish the role of different endothelin-receptor antagonists in the management of the Fontan circulation.

Plasma Drug Concentrations in Patients with Pulmonary Arterial Hypertension on Combination Treatment

BACKGROUND

Combination therapy with the phosphodiesterase type 5 inhibitors (PDE-5i) sildenafil or tadalafil and the endothelin receptor antagonists (ERA) bosentan, ambrisentan, or macitentan may cause mutual pharmacokinetic interactions in patients with pulmonary arterial hypertension (PAH).

OBJECTIVE

The objective of this study was to analyze plasma drug concentrations in PAH patients receiving different combination treatments.

METHODS

PAH patients receiving a stable combination treatment with ERA and PDE-5i with targeted dosage for at least 1 month were routinely assessed, including clinical parameters and plasma drug concentrations. Concentrations were normalized considering dose and time from last medication intake and presented as multiples of the expected mean (MoM) of the respective monotherapies.

RESULTS

A total of 125 PAH patients (84 female, 41 male, 57% idiopathic/heritable) were included. Sildenafil and tadalafil concentrations were lowest in combination with bosentan (MoM 0.44 ± 0.42, 95% confidence interval [CI] 0.30-0.57, and MoM 0.89 ± 0.53, 95% CI 0.50-1.28, respectively) compared to the combination with ambrisentan (MoM 1.3 ± 0.97, 95% CI 0.86-1.73, and MoM 1.67 ± 0.63, 95% CI 1.40-1.94, respectively) and macitentan (MoM 1.16 ± 0.87, 95% CI 0.86-1.46, and MoM 1.59 ± 0.99, 95% CI 0.80-2.38, respectively). The combination of sildenafil and bosentan led to more than twice the expected bosentan concentrations in 53.8%. Patients switching from sildenafil-bosentan to macitentan showed a significant increase in sildenafil concentrations (p < 0.001).

CONCLUSIONS

Only the combination with macitentan or ambrisentan led to targeted mean PDE-5i plasma concentrations and should therefore be preferred to combination with bosentan. Sildenafil-bosentan showed the strongest interaction, with low sildenafil and high bosentan concentrations. The study was not powered to analyze whether lower PDE-5i concentrations cause unsatisfying clinical response. However, plasma concentrations within a targeted range are desirable and may become of increasing importance.

Early Experience of Macitentan for Pulmonary Arterial Hypertension in Adult Congenital Heart Disease

BACKGROUND

Endothelin receptor antagonists (ERA) have been recognised as effective therapy for pulmonary arterial hypertension in congenital heart disease (CHD-PH), and Eisenmenger syndrome (ES) since The Bosentan Randomized Trial of Endothelin Antagonist Therapy-5 (Breathe 5) study. A new dual receptor antagonist - Macitentan - is currently undergoing trials to determine its efficacy in simple ES. To date there is little information on this therapy in CHD and we report our first experience, some with more complex diseases.

METHODS

Data was collected prospectively from September 2014. Patients with CHD-PH were started on or converted to macitentan if they required therapy with phosphodiesterase 5 inhibitor (PDE5i) or if there was insufficient response or a reaction to bosentan, especially those with trisomy 21. Patients were seen approximately three months after starting therapy to assess echocardiography, six minute walk test, clinical response and tolerability. All patients underwent monthly liver tests initially, but this was reduced to three-monthly in Q4 2015.

RESULTS

Fifteen patients with CHD-PH (eight male, seven female) were started on macitentan, median (range) age 38 (23-61) years, and eight patients with Down's syndrome. Eight patients had complex CHD with one having unoperated double inlet left ventricle with ventriculo-arterial discordance, one had double outlet right ventricle and six with complete atrio-ventricular septal defect. Six patients were ERA naïve and nine patients changed from bosentan to macitentan in order to achieve improved drug-drug interaction. Median length of time of treatment with macitentan is 289 (0-694) days to date. One discontinued due to rash and feeling unwell; one was unable to comply with medication due to learning difficulties and one died soon after commencing rescue therapy. This last patient was functional class IV with oxygen saturation of 67% at rest, with right heart failure and was unable to perform a walk test before commencing therapy. All patients who remained on therapy had significant increase in six minute walk test from median 286 (120-426) to 360m (150-450)(p <0.05), most notably in those treatment naïve. Functional class median remained at 3 but the range was reduced (1-3). Resting oxygen saturations improved from median 83 range (77-95%) at rest to 91 (77-96%) and at end walk from 78 (48-90%) to 79 (62-96%). Tricuspid regurgitant peak Doppler derived pressure drop did not change (as expected) at 4.6 (4.3-5.5)m/s. There were no episodes of liver dysfunction.

CONCLUSIONS

The introduction of this new therapy has been simple and mostly well tolerated in our sick group of patients. With the usual reservations concerning the open-label nature of our observations, macitentan has good signals regarding oxygen saturations and encouraging signals relating to efficacy.

Bosentan and macitentan prevent the endothelial-to-mesenchymal transition (EndoMT) in systemic sclerosis: in vitro study

BACKGROUND

Systemic sclerosis (SSc) is characterized by early vascular abnormalities and subsequent fibroblast activation to myofibroblasts, leading to fibrosis. Recently, endothelial-to-mesenchymal transition (EndoMT), a complex biological process in which endothelial cells lose their specific markers and acquire a mesenchymal or myofibroblastic phenotype, has been reported in SSc. In the present study, we evaluated the ability of endothelin-1 (ET-1) dual receptor antagonists bosentan (BOS) and macitentan (MAC) to antagonize EndoMT in vitro.

METHODS

Ten women with limited SSc were enrolled. They underwent double skin biopsy (affected and nonaffected skin). Fibroblasts and microvascular endothelial cells (MVECs) were isolated from biopsies. We performed mono- or coculture of MVECs (isolated from nonaffected skin) with fibroblasts (isolated from affected skin and stimulated with ET-1 and transforming growth factor beta [TGF-β]). In cocultures, the MVEC layer was left undisturbed or was preincubated with BOS or MAC. After 48 h of coculture, MVECs were analyzed for their tube formation ability and for messenger RNA and protein expression of different vascular (CD31, vascular endothelial growth factor-A [VEGF-A], VEGF-A165b) and profibrotic (alpha-smooth muscle actin [α-SMA], collagen type I [Col I], TGF-β) molecules.

RESULTS

After 48 h, MVECs showed a reduced tube formation ability when cocultured with SSc fibroblasts. CD31 and VEGF-A resulted in downregulation, while VEGF-A165b, the antiangiogenic isoform, resulted in upregulation. At the same time, mesenchymal markers α-SMA, Col I, and TGF-β resulted in overexpression in MVECs. Tube formation ability was restored when MVECs were preincubated with BOS or MAC, also reducing the expression of mesenchymal markers and restoring CD31 expression and the imbalance between VEGF-A and VEGF-A165b.

CONCLUSIONS

With this innovative EndoMT in vitro model realized by coculturing nonaffected MVECs with affected SSc fibroblasts, we show that the presence of a myofibroblast phenotype in the fibroblast layer, coupled with an ET-1-TGF-β synergic effect, is responsible for EndoMT. BOS and MAC seem able to antagonize this phenomenon in vitro, confirming previous evidence of endothelium-derived fibrosis in SSc and possible pharmacological interference.

Endothelin receptor antagonist macitentan or deletion of mouse mast cell protease 4 delays lesion development in atherosclerotic mice

AIMS

To determine the impact of mixed endothelin receptor antagonist and mouse mast cell protease-4 (mMCP-4) in the development of atherosclerosis in the mouse model.

MATERIALS AND METHODS

Apolipoprotein E (ApoE) KO mice were crossed with mMCP-4 KO mice to generate ApoE/mMCP-4 double KO mice. Atherosclerosis was induced with a normal- or high-fat diet for 12, 27 or 52weeks. Macitentan (30mg/kg/day), a dual ETA/ETB receptor antagonist, was given orally for 6weeks (27week protocol). At sacrifice, aortas and brachiocephalic arteries (BCAs) were collected. En face Sudan IV staining was performed on aortas and BCA sections were subjected to Masson's trichrome stain and α-smooth muscle actin labeling.

KEY FINDINGS

Under normal diet, both macitentan treatment and the absence of mMCP-4 reduced the development of aortic atherosclerotic lesions in 27-week old ApoE KO mice, but mMCP-4 deletion failed to maintain this effect on 52-week old mice. Under high-fat diet (WD), macitentan, but not the absence of mMCP-4, reduced aortic lesion development in ApoE KO mice. On BCA lesions of 27-week old WD mice, macitentan treatment had a small impact while mMCP-4 deletion showed improved features of plaque stability.

SIGNIFICANCE

These results suggest that the inhibition of mMCP-4 reduces lesion spreading in the earlier phases of atherosclerosis development and can help stabilise the more advanced plaque. Macitentan treatment was more effective to prevent lesion spreading but did not improve plaque features to the same extent.

Macitentan blocks endothelin-1 receptor activation required for chemoresistant ovarian cancer cell plasticity and metastasis

AIMS

In epithelial ovarian cancer (EOC), activation of endothelin-1 (ET-1)/endothelin A receptor (ETAR) and ET-1/ETBR signaling is linked to many tumor promoting effects, such as proliferation, angiogenesis, invasion, metastasis and chemoresistance. Understanding how to hamper the distinct mechanisms that facilitate epithelial plasticity and propagation is therefore central for improving the clinical outcome for EOC patients.

MAIN METHODS

The phosphorylation status of Akt and MAPK was evaluated by immunoblotting in A2780 and 2008 EOC cell lines and their cisplatinum-resistant variants. Vasculogenic mimicry was analyzed by vascular tubules formation assay. Tumor growth and metastases inhibition was performed in chemoresistant EOC xenografts.

KEY FINDINGS

We found that the dual ETAR/ETBR antagonist macitentan was able to inhibit the ET-1-induced activation of Akt and MAPK signaling pathways in chemoresistant EOC cells. Moreover, chemoresistant EOC cells displayed higher capability to engage vasculogenic mimicry compared to sensitive cells that was inhibited after treatment with macitentan. Finally, the specific ETAR antagonist zibotentan was less efficacious compared to macitentan to suppress tumor growth in chemoresistant EOC xenografts and the co-treatment of macitentan and cisplatinum reduced the metastatic progression.

SIGNIFICANCE

Our findings better clarify the ET-1-induced molecular mechanisms underlying the aggressive behavior of chemoresistant EOC cells. These results also support the use of macitentan in combination with chemotherapy as a rational therapeutic strategy for circumventing drug resistance in EOC.

Simultaneous determination of macitentan and its active metabolite in human plasma by liquid chromatography-tandem mass spectrometry

Macitentan is a newly approved endothelin receptor antagonist (ERA) for the long-term treatment of PAH with superior receptor-binding properties and a longer duration of action compared to other available ERAs. However, analytical methods for simultaneous determination of macitentan and its active metabolite, ACT-132577, in human plasma have not been fully reported in the literature. In this work, a fast, sensitive, and reliable high-performance liquid chromatography-tandem mass spectrometry method (HPLC-MS/MS) was firstly developed and completely validated for simultaneous determination of macitentan and its active metabolite in human plasma. Plasma samples were processed with a protein precipitation using acetonitrile, followed by chromatographic separation using an Inertsil ODS-SP column (100×2.1mm, 3.5μm) under isocratic elution with a mobile phase consisting of acetonitrile and 0.2% formic acid at a flow rate of 0.3mL/min. Quantification was operated in multiple reaction monitoring (MRM) mode using the transitions m/z 547.1→201.0 for macitentan, m/z 589.0→203.0 for ACT-132577, and m/z 380.5→243.3 for the IS (donepezil). The assay exhibited a linear range of 1-500ng/mL for both macitentan and ACT-132577. The accuracy and the intra- and inter-precisions were within acceptable ranges and no significant matrix effect was observed during the method validation. The developed method was successfully utilized to a human pharmacokinetic study of macitentan as well as ACT-132577 after oral administration of 10mg macitentan tablet in healthy Chinese volunteers.

Macitentan treatment retards the progression of established pulmonary arterial hypertension in an animal model

BACKGROUND

Macitentan is a new endothelin receptor antagonist that is used to treat pulmonary arterial hypertension in humans. Treatment of established pulmonary hypertension with macitentan was studied using the monocrotaline model of pulmonary hypertension.

METHODS

Three groups of rats were created (n=12): control (CON: macitentan only), monocrotaline (MCT: monocrotaline only) and macitentan (MACI: macitentan and monocrotaline). Monocrotaline (60 mg/kg) was injected in the MCT and MACI groups on day 0; volume matched saline was injected in the CON groups. Macitentan therapy (30 mg/kg/day) was commenced on day 11 in the CON and MACI groups. Serial echocardiography and ECGs were performed. The rats were sacrificed if they showed clinical deterioration.

RESULTS

The MCT and MACI rats showed signs of pulmonary hypertension by day 7 (maximum pulmonary velocity, CON 1.15 ± 0.15m/s vs MCT 1.04 ± 0.10 m/s vs MACI 0.99 ± 0.18 m/s; p<0.05). Both the MCT and MACI groups developed pulmonary hypertension, but this was less severe in the MACI group (day 21 pulmonary artery acceleration time, MCT 17.55 ± 1.56 ms vs MACI 22.55 ± 1.00 ms; pulmonary artery deceleration, MCT 34.72 ± 3.72 m/s(2) vs MACI 17.30 ± 1.89 m/s(2); p<0.05). Right ventricular hypertrophy and QT interval increases were more pronounced in MCT than MACI (right ventricle wall thickness, MCT 0.13 ± 0.1cm vs MACI 0.10 ± 0.1cm; QT interval, MCT 85 ± 13 ms vs MACI 71 ± 14 ms; p<0.05). Survival benefit was not seen in the MACI group (p=0.50).

CONCLUSIONS

Macitentan treatment improves haemodynamic parameters in established pulmonary hypertension. Further research is required to see if earlier introduction of macitentan has greater effects.

Macitentan for the treatment of pulmonary arterial hypertension

Macitentan is a novel, dual endothelin receptor antagonist recently approved for the treatment of WHO Group I pulmonary arterial hypertension. Its pharmacologic mechanism of action as well as the pharmacokinetics, pharmacodynamics and potential drug-drug interactions have been demonstrated in multiple phase I and II trials. The pivotal randomized, placebo-controlled, event-driven clinical trial revealed a significant reduction in morbidity. The most common adverse events were rarely clinically significant, nor did they result in a high rate of discontinuation. Of note, macitentan is contraindicated in pregnant women due to embryo-fetal toxicity.