Clinical use of macitentan in the treatment of connective tissue disease-associated pulmonary arterial hypertension

Background

Connective tissue disease (CTD) is the second most common cause of the pulmonary arterial hypertension (PAH). Currently, clinical data concerning CTD-PAH is scarce. Our study aimed to assess the efficacy and safety of macitentan in the treatment of CTD-PAH.

Methods

In this retrospective study, patients diagnosed with CTD-PAH at The First Affiliated Hospital of Soochow University from April 2020 to November 2021 were included. Of the patients, 9 were switched to macitentan monotherapy whereas 23 received initial combination therapy. The mean follow-up time was 24 weeks. Six-minute walking distance (6MWD), World Health Organization functional class (WHO-FC), serum N-terminal pro-brain natriuretic peptide (NT-proBNP), and echocardiography parameters before and after medication were assessed. Adverse reactions were also recorded and compared.

Results

After 24 weeks of treatment, 6MWD, NT-proBNP, systolic pulmonary artery pressure (sPAP) estimated by ultrasound, tricuspid regurgitation pressure gradient (TRPG) and tricuspid annular plane systolic excursion (TAPSE) in the macitentan monotherapy group revealed significant differences (Z=-2.67, Z=-2.67, t=6.20, t=5.60, t=-3.04, P<0.05). There were no statistically significant differences in right ventricular diameter (RVD), right atrial diameter (RAD), ascending aortic root inner diameter (AAO) and left ventricular end-diastolic diameter (LVEDd) (P>0.05). After 24 weeks of medication, the number of patients with WHO-FC grade III/IV symptoms decreased from 6 to 3, 1 to 0 respectively (P<0.05), and that of patients with WHO-FC grade I/II symptoms increased from 0 to 2, 2 to 4 respectively(P<0.05). After 24 weeks of treatment, 6MWD, NT-proBNP, LVEDd, sPAP and TRPG in the macitentan combined with sildenafil treatment group revealed statistically significant differences (Z=-4.11, Z=-3.74, Z=-3.83, t=6.88, t=6.54, P<0.001). Significant differences in RVD, RAD, and TAPSE were found (t=3.46, t=3.69, t=-3.12, P<0.05). There were no statistically significant variances in AAO between the groups (P>0.05). The number of patients with WHO-FC grade III/IV symptoms decreased from 16 to 8, 5 to 0 respectively (P<0.05), and that of patients with WHO-FC grade I/II symptoms increased from 0 to 1, 2 to 14 respectively (P<0.001). There were no statistically significant differences before and after treatment in 6MWD, NT-proBNP, RVD, RAD, AAO, LVEDd, sPAP, TRPG and TAPSE between the two groups (P>0.05). There were no statistically significant differences in alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum creatinine (Scr) and hemoglobin (Hb) between 0 and 24 weeks (P>0.05).

Conclusions

Exercise tolerance and cardiac function in patients with CTD-PAH were significantly improved after treatment with macitentan, which was well tolerated. Therefore, macitentan may be an effective and safe targeted drug for CTD-PAH.

Randomized Trial of Macitentan/Tadalafil Single-Tablet Combination Therapy for Pulmonary Arterial Hypertension

BACKGROUND

Endothelin receptor antagonist (ERA) and phosphodiesterase 5 inhibitor (PDE5i) combination therapy is recommended for low-/intermediate-risk pulmonary arterial hypertension (PAH) patients. A fixed-dose combination of the ERA macitentan and PDE5i tadalafil (M/T FDC) in a once-daily, single tablet would simplify treatment.

OBJECTIVES

The multicenter, double-blind, adaptive phase 3 A DUE study investigated the efficacy and safety of M/T FDC vs macitentan 10 mg and vs tadalafil 40 mg monotherapies in PAH patients, including treatment-naïve and prior ERA or PDE5i monotherapy-treated patients.

METHODS

World Health Organization functional class II-III patients were randomized to M/T FDC, macitentan, or tadalafil depending on their PAH treatment (treatment-naïve, ERA, or PDE5i monotherapy) at baseline. The primary endpoint was change in pulmonary vascular resistance (PVR) at week 16.

RESULTS

In total, 187 patients were randomized to single-tablet M/T FDC (n = 108), macitentan (n = 35), or tadalafil (n = 44). PVR reduction with M/T FDC was significantly greater vs macitentan (29%; geometric mean ratio 0.71; 95% CL: 0.61-0.82; P < 0.0001) and vs tadalafil (28%; geometric mean ratio 0.72; 95% CL: 0.64-0.80; P < 0.0001). Three patients died in the M/T FDC arm (judged unrelated to treatment). Adverse events (AEs) leading to discontinuation, serious AEs, and those of special interest (anemia, hypotension, and edema) were more frequent with M/T FDC.

CONCLUSIONS

Macitentan and tadalafil FDC significantly improved PVR vs monotherapies in PAH patients, with a safety and tolerability profile consistent with the individual components. The A DUE study supports M/T FDC as a once-daily, single-tablet combination for initial therapy and escalation to double combination therapy in patients with PAH. (Clinical Study to Compare the Efficacy and Safety of Macitentan and Tadalafil Monotherapies With the Corresponding Fixed-dose Combination Therapy in Subjects With Pulmonary Arterial Hypertension [PAH]) [A DUE]; NCT03904693).

Current Management and Future Directions for Pulmonary Arterial Hypertension Associated with Congenital Heart Disease

Current management of patients with congenital heart disease has increased their survival into adulthood. This is accompanied by potential cardiac complications, including pulmonary hypertension associated with congenital heart disease (PAH-CHD). PAH-CHD constitutes a challenging subgroup of pulmonary hypertension and requires expert management to improve quality of life and prognosis. Novel agents have shown a significant improvement in morbidity and mortality in patients with pulmonary arterial hypertension. However, the long-term effects of these medications on PAH-CHD patients remain somewhat uncertain, necessitating treatment plans largely founded on the clinical experience of the healthcare providers. The aim of this review is to summarize the current evidence and future perspectives regarding treatment strategies for PAH-CHD to help better guide management of this complex disease.

Macitentan Administration for Pulmonary Hypertension Due to β-thalassemia with Multiple Organ Failure: A Case Report

A 51-year-old Thai woman diagnosed with β-thalassemia underwent regular blood transfusion and iron-chelating therapy. However, after voluntarily discontinuing treatment, the patient developed progressive dyspnea and was diagnosed with pulmonary hypertension following right heart catheterization. Despite resuming blood transfusions, her condition did not improve. Because the patient had a history of multiple organ failure, curative treatment for β-thalassemia was not feasible, and macitentan was administered. Despite experiencing hypotension as an adverse event, her condition remained stable during macitentan treatment. Thus, macitentan may be well tolerated in patients with pulmonary hypertension caused by β-thalassemia with multiple organ dysfunction.

Efficacy and safety of macitentan for pulmonary hypertension: A meta-analysis

INTRODUCTION

Our purpose of this study is to evaluate the effect and safety of macitentan in the treatment of pulmonary hypertension (PH).

METHODS

We retrieved the safety and efficacy of macitentan treatment for PH using PubMed, the Cochrane Library, EMBASE databases and clinicaltrials.gov. The Cochrane Risk of Bias Tool was used for literature screening and quality assessment. Data analysis was conducted using RevMan 5.4.1 and Stata/SE 15.1 software. Results are presented as standardization mean differences (SMDs) and odds ratio (OR).

RESULTS

Meta-analysis of seven randomized controlled trial (RCT) studies and four non-RCT studies with 2769 patients was included, involving 723 in the macitentan group and 599 in the placebo group. The results of the study showed that macitentan had effectively decreased pulmonary vascular resistance (PVR) (SMD = -0.53, 95% CI: -0.77--0.29, p < 0.05), cardiac index (CI) (SMD = 0.60, 95% CI: 0.37-0.83, p < 0.05) and N-terminal pro-brain natriuretic peptide (NT-proBNP) (SMD = -0.22, 95% CI: -0.40--0.03, p < 0.05). Furthermore, macitentan also significantly reduced PVR (SMD = -0.58, 95% CI: -0.80--0.35, p < 0.05), 6-min walk distance (6WMD) (SMD = 0.33, 95% CI: 0.15-0.50, p < 0.05), CI (SMD = 0.48, 95% CI: 0.28-0.69, p < 0.05), mean pulmonary arterial pressure (mPAP) (SMD = -0.43, 95% CI: -0.64--0.23, p < 0.05) and NT-proBNP (SMD = -0.55, 95% CI: -1.07--0.03, p < 0.05) between baseline and follow-up. The adverse reactions to macitentan were mild, with headache, anaemia and bronchitis. Other efficacy and safety outcomes did not reach statistical differences.

CONCLUSION

Macitentan therapy for PH is effective and safe. The effectiveness on PVR, mPAP, mean right atrial pressure (mRAP), mortality and other indicators still needs to be further confirmed.

Long-term safety of macitentan in patients with pulmonary hypertension: A meta-analysis of randomised controlled trials

BACKGROUND

Macitentan has demonstrated its effectiveness in patients with pulmonary hypertension (PH), but its safety, especially for long-term use, needs to be further explored. This systematic review and meta-analysis aimed to determine the safety of long-term use of macitentan in patients with PH.

METHODS

A systematic search was made of PubMed, Embase, Cochrane Library and clinicaltrials.gov, without language restrictions. Randomised controlled trials (RCTs) on treatment of PH with macitentan, compared with placebo, were reviewed. Estimated effects of included studies were pooled as risk ratios (RRs), with 95% confidence intervals (CIs).

RESULTS

Six RCTs (enrolling 1003 participants) met the inclusion criteria. Anaemia (RR 3.86, 95% CI 2.05-7.30), headache (RR 1.52, 95% CI 1.02-2.26) and bronchitis (RR 2.24, 95% CI 1.30-3.87) were more frequent in the macitentan groups. There was no statistically significant difference in the proportion of patients with at least one adverse event (AE) or serious adverse event (SAE), AEs leading to discontinuation of study treatment, all-cause death, right ventricular failure (RVF) and peripheral oedema between the two groups.

CONCLUSIONS

The long-term use of macitentan is safe for patients with PH, although with a higher risk of anaemia, headache and bronchitis.

Benefits of Macitentan in Patients with Pulmonary Hypertension: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

This systematic review and meta-analysis aimed to determine the efficacy of macitentan in patients with pulmonary hypertension (PH).

Methods

A systematic search was made of PubMed, Embase, Cochrane Library, and clinicaltrials.gov, without language restrictions. Randomized controlled trials (RCTs) on treatment of PH with macitentan, compared with placebo or blank, were reviewed. Studies were pooled to weighted mean differences (WMDs) and risk ratios (RRs), with 95% confidence intervals (CIs).

Results

Six RCTs (enrolling 1,003 participants) met the inclusion criteria. Macitentan showed significant effects on 6-min walk distance (6MWD) (WMD 12.06 m, 95% CI 2.12 to 21.99 m), pulmonary vascular resistance (PVR) (WMD -186.51 dyn·s/cm-5, 95% CI -232.72 to -140.29 dyn·s/cm-5), mean pulmonary artery pressure (mPAP) (WMD -3.20 mmHg, 95% CI -5.93 to -0.47 mmHg), N-terminal pro-brain natriuretic peptide (NT-proBNP) (WMD -232.47 ng/L, 95% wCI -318.22 to -146.72 ng/L), and cardiac index (WMD 0.39 L/min/m2, 95% CI 0.20 to 0.58 L/min/m2).

Conclusion

Macitentan significantly improved 6MWD, PVR, mPAP, NT-proBNP, and cardiac index in patients with PH. Macitentan should be further validated in patients with PH.

Inhaled nintentanib, pirfenidone and macitentan for pulmonary fibrosis: a laboratory experiment

Aim: Idiopathic pulmonary fibrosis is a rare disease with few efficient drugs in the market. The consequences of this disease are mainly respiratory failure and pulmonary hypertension. Materials & methods: In our experiment we used the drugs pirfenidone, nintetanib and macitentan. We performed nebulization experiments with three jet nebulizers and three ultrasound nebulizers with different combinations of residual cup designs, and residual cup loadings in order to identify which combination produces droplets of less than 5 μm in mass median aerodynamic diameter. Results: Pirfenidone versus nintetanib had smaller droplet size formation at both inhaled technologies (1.37 < 2.23 and 1.92 < 3.11, jet and ultrasound respectively). Discussion: Pirfenidone and nintetanib can be administered as aerosol in any type of nebulization system.

Effects of bergapten on the pharmacokinetics of macitentan in rats both in vitro and in vivo

Macitentan was approved by the United States Food and Drug Administration (FDA) in 2013 for the treatment of pulmonary arterial hypertension (PAH). Bergapten is a furanocoumarin that is abundant in Umbelliferae and Rutaceae plants and is widely used in many Chinese medicine prescriptions. Considering the possible combination of these two compounds, this study is aimed to investigate the effects of bergapten on the pharmacokinetics of macitentan both in vitro and in vivo. Rat liver microsomes (RLMs), human liver microsomes (HLMs), and recombinant human CYP3A4 (rCYP3A4) were used to investigate the inhibitory effects and mechanisms of bergapten on macitentan in vitro. In addition, pharmacokinetic parameters were also studied in vivo. Rats were randomly divided into two groups (six rats per group), with or without bergapten (10 mg/kg), and pretreated for 7 days. An oral dose of 20 mg/kg macitentan was administered to each group 30 min after bergapten or 0.5% CMC-Na administration on day 7. Blood was collected from the tail veins, and the plasma concentrations of macitentan and its metabolites were assessed by ultra-performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS). Finally, we analyzed the binding force of the enzyme and two small ligands by in silico molecular docking to verify the inhibitory effects of bergapten on macitentan. The in vitro results revealed that the IC₅₀ values for RLMs, HLMs, and rCYP3A4 were 3.84, 17.82 and 12.81 μM, respectively. In vivo pharmacokinetic experiments showed that the AUC_(0-t), AUC_(0-∞), and C_max of macitentan in the experimental group (20,263.67 μg/L*h, 20,378.31 μg/L*h and 2,999.69 μg/L, respectively) increased significantly compared with the control group (7,873.97 μg/L*h, 7,897.83 μg/L*h and 1,339.44 μg/L, respectively), while the CL_z/F (1.07 L/h/kg) of macitentan and the metabolite-parent ratio (MR) displayed a significant decrease. Bergapten competitively inhibited macitentan metabolism in vitro and altered its pharmacokinetic characteristics in vivo. Further molecular docking analysis was also consistent with the experimental results. This study provides a reference for the combined use of bergapten and macitentan in clinical practice.

Current Status of Endothelin Receptor Antagonists in Pulmonary Arterial Hypertension: A Combined Study Results and Pharmacology-Based Review

Pulmonary arterial hypertension (PAH) affects a wide range of people globally and has a poor prognosis despite many advancements in available treatment options. Among the available treatments, endothelin receptor antagonists (ERA) are among the most widely used drugs. These drugs have been evaluated in scientific trials. We included free full texts in the English language from the last ten years and reviewed them. We are writing this review to amalgamate the pharmacological aspects and the previous studies on ERAs to demonstrate a comprehensive overview of the current status of ERAs for PAH treatment. We focused on the structure, pharmacodynamics, pharmacokinetics, and efficacy and safety of the three most widely used ERAs: Bosentan, Ambrisentan, and Macitentan. These drugs have different receptor affinities, bioavailability, excretion routes, and different levels of safety profiles. There are three available studies, the RCT, the ARIES series, and the SERAPHIN studies, for assessing the safety and efficacy of Bosentan, Ambrisentan, and Macitentan, respectively. All the studies and some additional studies for combination therapy have proven all three drugs effective in treating PAH. The side effects (SE) varied from headache and hepatic enzyme elevation to worsening the PAH status of varied severities. Although these studies provided valuable insight into the role of ERAs, there is still enough scope for more studies on ERAs, both as monotherapy and combination therapy for PAH.

The endothelin receptor antagonist macitentan ameliorates endothelin-mediated vasoconstriction and promotes the survival of retinal ganglion cells in rats

Glaucoma is a chronic and progressive eye disease, commonly associated with elevated intraocular pressure (IOP) and characterized by optic nerve degeneration, cupping of the optic disc, and loss of retinal ganglion cells (RGCs). The pathological changes in glaucoma are triggered by multiple mechanisms and both mechanical effects and vascular factors are thought to contribute to the etiology of glaucoma. Various studies have shown that endothelin-1 (ET-1), a vasoactive peptide, acting through its G protein coupled receptors, ETA and ETB, plays a pathophysiologic role in glaucoma. However, the mechanisms by which ET-1 contribute to neurodegeneration remain to be completely understood. Our laboratory and others demonstrated that macitentan (MAC), a pan endothelin receptor antagonist, has neuroprotective effects in rodent models of IOP elevation. The current study aimed to determine if oral administration of a dual endothelin antagonist, macitentan, could promote neuroprotection in an acute model of intravitreal administration of ET-1. We demonstrate that vasoconstriction following the intravitreal administration of ET-1 was attenuated by dietary administration of the ETA/ETB dual receptor antagonist, macitentan (5 mg/kg body weight) in retired breeder Brown Norway rats. ET-1 intravitreal injection produced a 40% loss of RGCs, which was significantly lower in macitentan-treated rats. We also evaluated the expression levels of glial fibrillary acidic protein (GFAP) at 24 h and 7 days post intravitreal administration of ET-1 in Brown Norway rats as well as following ET-1 treatment in cultured human optic nerve head astrocytes. We observed that at the 24 h time point the expression levels of GFAP was upregulated (indicative of glial activation) following intravitreal ET-1 administration in both retina and optic nerve head regions. However, following macitentan administration for 7 days after intravitreal ET-1 administration, we observed an upregulation of GFAP expression, compared to untreated rats injected intravitreally with ET-1 alone. Macitentan treatment in ET-1 administered rats showed protection of RGC somas but was not able to preserve axonal integrity and functionality. The endothelin receptor antagonist, macitentan, has neuroprotective effects in the retinas of Brown Norway rats acting through different mechanisms, including enhancement of RGC survival and reduction of ET-1 mediated vasoconstriction.

Macitentan for the Treatment of Refractory Digital Ulcers in Patients With Connective Tissue Diseases

Systemic sclerosis (SSc) is a chronic autoimmune disease with complex pathogenesis, characterized by vascular dysfunction and fibrosis. Digital ulcers (DUs) are a common and severe complication in SSc patients, negatively impacting their quality of life. This retrospective study evaluates the use of macitentan, an endothelin receptor antagonist, in six female patients with connective tissue disease (CTD) and sclerodermiform features (five SSc and one mixed connective tissue disease) for the treatment of refractory DUs. Macitentan demonstrated a safe and effective alternative to bosentan, reducing DU relapses, hospitalizations, and the use of systemic prostaglandin therapy. The findings suggest that macitentan may be a valuable therapeutic option in specific cases of recurrent or refractory DUs and warrant further investigation in larger, long-term studies.

Cost-Effectiveness Analysis of Macitentan in Comparison With Bosentan in the Treatment of Pulmonary Arterial Hypertension in Iran

OBJECTIVES

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease that, if left untreated, shortens the life expectancy of patients. Endothelin receptor antagonists, such as macitentan and bosentan, play an essential role in improving the patient's symptoms, quality of life, and life expectancy. This study aimed to evaluate the cost-utility of macitentan compared with bosentan in treating PAH from the health system perspective in Iran.

METHODS

For evaluating the cost-effectiveness of macitentan, a Markov model consisting of 5 states, functional class (FC) I, FC II, FC III, FC IV, and death, was designed using the TreeAge software. The lifetime time horizon and a 3-month cycle length were set. Patients entered the model from FC II or FC III states based on the initial probabilities. Costs were measured in US dollars (USD), and outcomes were measured in terms of quality quality-adjusted life-years (QALYs). Consequently, the incremental cost-effectiveness ratio (ICER) was calculated. In addition, sensitivity analysis was performed to determine the robustness of the model by examining the possible effects of uncertainties on the final result.

RESULTS

The costs of treatment with macitentan and bosentan in PAH in Iran were calculated at 19 429 and 17 246 USD, and the outcomes were 4.02 and 3.04 QALYs, respectively. Therefore, ICER was calculated at 2233.46 USD/QALY. One-way sensitivity analysis demonstrates that the model is robust; nevertheless, it is most sensitive to the price of macitentan and bosentan.

CONCLUSION

Treatment with macitentan was associated with both higher costs and QALYs than bosentan. Nevertheless, it is considered the cost-effective treatment strategy in Iran given that the calculated ICER falls below the willingness to pay threshold.

Efficacy and safety of switching from bosentan or ambrisentan to macitentan in pulmonary arterial hypertension: A systematic review and meta-analysis

Background

There is little evidence of the effectiveness of switching from the endothelin receptor antagonists (ERAs) bosentan and ambrisentan to a novel ERA, macitentan, in patients with pulmonary arterial hypertension (PAH). Therefore, a systematic review and meta-analysis was performed to evaluate the efficacy and safety of patients with PAH switching from other ERAs to macitentan.

Methods

We retrieved the relevant literature published before January 2022 for the meta-analysis from the PubMed, EMBASE, and Cochrane Library databases. Efficacy included changes in the 6-min walk distance (6MWD), World Health Organization functional class (WHO-FC), N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, hemodynamics, echocardiography and survival.

Results

Nine studies, consisting of 408 PAH patients, that met the inclusion criteria were included. The switch from bosentan or ambrisentan to macitentan effectively increased the 6MWD by 20.71 m (95% CI: 10.35-31.07, P < 0.00001, I ² = 0%). Six months after conversion, the tricuspid annular plane systolic excursion was found to improve from 19.0 ± 4.0 to 21.0 ± 5.0 mm in adults and from 16.00 ± 5.0 to 18.25 ± 4.8 mm in children. Ordinal logistic regression showed that the WHO-FC significantly improved by 0.412 (95% CI: 0.187-0.908, P = 0.028). The switch did not show significant improvement in NT-proBNP levels. In addition, the switch was well tolerated.

Conclusion

The switch from bosentan or ambrisentan to macitentan significantly increased the 6MWD in PAH patients, improved the WHO-FC, and exerted safety benefits. The effects of the switch on NT-proBNP levels, hemodynamics, and echocardiography still need to be further confirmed.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/], identifier [CRD42021292554].

The Consistent Effectiveness and Safety of Macitentan Therapies Across Idiopathic and Congenital Heart Disease-Associated PulmonaryArterial Hypertension: A Single-Center Experience

BACKGROUND

In this single-center study, we evaluated efficacy and safety issues and predictors of survival in patients with idiopathic and congenital heart disease-associated pulmonary arterial hypertension who were under macitentan therapies.

METHOD

Our study retrospectively evaluated 221 patients with pulmonary arterial hypertension enrolled in our single-center study, and mono, dual, and triple macitentan therapies were noted in 30, 115, and 76 patients, respectively. The longitudinal changes in clinical, neurohumoral, and echocardiographic measures of pulmonary arterial hypertension were evaluated. The Registry to Evaluate Early and Long-Term Pulmonary Arterial Hypertension Disease Management, Registry to Evaluate Early and Long-Term Pulmonary Arterial Hypertension Disease Management 2.0, and Registry to Evaluate Early and Long- Term Pulmonary Arterial Hypertension Disease Management Lite 2 scores at baseline, Swedish PAH Registry, Comparative Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension registry, and French Pulmonary Hypertension Network registry risk status both at baseline and first control were assessed.

RESULT

The median follow-up period was 1068 [415-2245] days. Macitentan was associated with significant improvements in functional class, 6-minute walk distance, N-terminal pro-brain natriuretic peptide (NT-proBNP), and echocardiographic measures without any deterioration of hemoglobin or hepatic enzymes. The low-risk scores with each model at baseline and/or first control are related to significantly better survival. Age, gender, and log-NT-proBNP in time-fixed and idiopathic pulmonary arterial hypertension, and log-NT-proBNP in time-dependent Cox proportional hazard regression analyses were independent predictors of mortality.

CONCLUSION

Mono- or sequential combination macitentan therapies were associated with sustained benefits in functional class, 6-minute walk distance, NT-proBNP, and echocardiographic measures in patients with idiopathic pulmonary arterial hypertension and congenital heart disease-associated pulmonary arterial hypertension, and low-risk scores at baseline and/or first controls can be translated to better survival.

Protective Effect of Triclosan in Monocrotaline-Induced Pulmonary Arterial Hypertension: FASN Inhibition a Novel Approach

Background

Novel pharmacological approaches are needed to improve the outcomes of patients with idiopathic pulmonary hypertension. Fatty acid synthase (FASN) 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.

Objective

We compared a Triclosan (FASN inhibitor), for the first time with the dual endothelin receptor antagonist, macitentan, in a monocrotaline-induced rat pulmonary hypertension model.

Methods

Different methods (hemodynamics, histology of right ventricle and pulmonary vessels, and circulating biomarkers) showed consistently that 30 mg/kg daily of Triclosan (FASN inhibitor) and 10 mg/kg daily of macitentan slowed the progression of PAH both at the functional and structural levels.

Results

Treatments started on day 14 after monocrotaline injection and lasted 14 days. The findings of all experimental methods show that the FASN inhibitor has more similar effects as compared to macitentan.

Conclusion

Our study reveals that inhibition of FAS decreases RV hypertrophy and improves cardiac function associated with PAH with the regulation of metabolic functions and governs further studies to establish "FASN inhibitor as a potential therapeutic approach" for the management of PAH.

Effects of Concomitant Administration of PXR Ligand Drugs on the Anticoagulant Effects of Warfarin

We encountered cases in which the anticoagulant effects of warfarin (CYP2C9 substrate) were reversibly attenuated by the concomitant administration of rifampicin or bosentan, which are potent pregnane X receptor (PXR) ligands. The purpose of the present study is to report the previous case with rifampicin, and to evaluate the changes in the warfarin anticoagulant effects when withdrawing or switching bosentan treatment. The former is a case study of a 4-year-old girl undergoing warfarin treatment. The latter is a longitudinal study of 20 pediatric patients receiving stable warfarin treatment. The prothrombin time and international normalized ratio (PT-INR) values were extracted from the medical records and normalized by the daily-dose per body size as an index for the warfarin anticoagulant effects. Rifampicin treatment resulted in a 52.0% decrease in the anticoagulant index. On the other hand, 10 of 20 patients started bosentan and their anticoagulant index was reduced by a median of 2.00. Bosentan was withdrawn in 4 of 20 patients and their anticoagulant index increased by a median of 3.67. Six of 20 patients switched from bosentan to macitentan, which is considered not to activate PXR in clinical settings. However, switching from bosentan to macitentan resulted in a median of 2.25 reduction of the anticoagulant index rather than recovery of the response to warfarin. This study suggests not only the possibility of heterogeneity in the response to PXR activation and deactivation, but also the importance of long-term monitoring of drug-drug interactions when switching from bosentan to macitentan.

The Transition From Ambrisentan to Macitentan in Patients With Pulmonary Arterial Hypertension: A Real-word Prospective Study

Background: In a long-term event-driven trial, macitentan has demonstrated beneficial time to clinical worsening in patients with pulmonary arterial hypertension (PAH) and reduced PAH-related hospitalization rates compared with placebo. Macitentan is the most recently approved endothelin receptor antagonist (ERA) and is the first ERA that has shown efficacy for morbidity and mortality in PAH patients; therefore, patients and physicians may consider converting treatment from ambrisentan to macitentan. Our study evaluated the safety, efficacy, and quality of life in PAH patients transitioning from ambrisentan to macitentan. Methods: This was a real-world, prospective study with a 12-month follow-up. PAH patients who had received stable doses of ambrisentan for over 3 months, were within the World Health Organization Functional Class II/III, and 6-min walk distance ≥ of 250 m were enrolled. The study included a screening period, followed by a transition phase, after which patients entered the long-term follow-up. Clinical data and treatment satisfaction outcomes were collected to assess and monitor the safety and efficacy of the transition. The trial was registered at the Chinese Clinical Trial Registry (www.chictr.org.cn; No. ChiCTR2000034898). Results: One hundred and fifty-seven enrolled PAH patients completed the transition. All criteria for continuous treatment transition were met by 145 patients (92.4%). Results showed improvements in exercise capacity, cardiac function, and hemodynamics compared with baseline. During the process, 4 patients discontinued macitentan due to adverse events. There was no statistical difference in the overall incidence of adverse events before and after the transition. Conclusion: Transition to macitentan from ambrisentan was successful and well-tolerated by PAH patients, and was associated with greater efficacy and satisfaction.

The clinical experience of macitentan in pulmonary hypertension in Indian cohort: 12-month follow-up

Background:

The effectiveness and safety of macitentan, an endothelin-receptor antagonist (ERA) in the treatment of pulmonary arterial hypertension (PAH), has been demonstrated in numerous randomized clinical trials including SERAPHIN, focused on the reduction of morbidity and mortality.

Objectives:

Our aim was to demonstrate the clinical and echocardiographic progression using macitentan in Indian patients with PAH.

Settings and Design:

It was a retrospective study of 20 patients with multiple etiologies of PAH who had begun macitentan in routine clinical practice from a single center. There were 55% of patients with existing PAH therapies.

Subjects and Methods:

The World Health Organization functional class (WHO-FC), 6-min walking distance, N-terminal prohormone of brain natriuretic peptide level (NT-pro-BNP), and echocardiographic data such as tricuspid annular plane systolic excursion (TAPSE), systolic pulmonary artery pressure (sPAP), and the occurrence of pericardial effusion were collected at baseline and 12-month follow-up. The statistical analysis was performed using SPSS software.

Results:

Of the 20 PAH patients, 70% were women. The majority were in WHO FC II (50%), while 35% were in FC III and 15% were in FC IV. The mean age was 43.4 years at the start of the therapy with macitentan. After 6 months of macitentan therapy, 85% showed substantial improvement in their FC, each increased its 6-min walking distance test (P < 0.0001), and there was a significant reduction in plasma levels of NT-pro BNP (P < 0.0001). There has also been an improvement in echocardiographic parameters such as TAPSE and sPAP (P < 0.0001).

Conclusions:

Our findings indicate that macitentan has been well tolerated and beneficial in Indian patients with PAH and further, future research is required to verify these results.

Novel Targets in a High-Altitude Pulmonary Hypertension Rat Model Based on RNA-seq and Proteomics

High-altitude pulmonary hypertension (HAPH) is a complication arising from an inability to acclimatize to high altitude and is associated with high morbidity and mortality. We aimed to analyze the effects of macitentan, selexipag, riociguat, and reoxygenation on HAPH, and to screen possible targets of these treatments for future drug screening. Rats were subjected to hypobaric hypoxia for 35 days to induce HAPH, and treated with vehicle or selexipag, macitentan, riociguat, or with reoxygenation, from days 21 to 35. Selexipag, macitentan, and reoxygenation prevented an increase in mean pulmonary artery pressure and hypoxia-induced right ventricular hypertrophy, compared to the vehicle. Riociguat had little effect. RNA-seq and proteomics revealed strong correlations between responses to the three drugs, which had almost identical effects. GO-enrichment revealed that the differentially expressed genes included those involved in metabolic regulation, transcription, and translation. Various molecular pathways were annotated. Selexipag, macitentan, and reoxygenation ameliorated HAPH. Serpina1, Cryz, and Cmc1 were identified, via multi-omics screening, as key genes involved in HAPH. These findings provide new insights into the targeted drug mechanisms in HAPH.

The REPAIR Study: Effects of Macitentan on RV Structure and Function in Pulmonary Arterial Hypertension

OBJECTIVES

The REPAIR (Right vEntricular remodeling in Pulmonary ArterIal hypeRtension) study evaluated the effect of macitentan on right ventricular (RV) and hemodynamic outcomes in patients with pulmonary arterial hypertension (PAH), using cardiac magnetic resonance (CMR) and right heart catheterization (RHC).

BACKGROUND

RV failure is the primary cause of death in PAH. CMR is regarded as the most accurate noninvasive method for assessing RV function and remodeling and CMR measures of RV function and structure are strongly prognostic for survival in patients with PAH. Despite this, CMR is not routinely used in PAH clinical trials.

METHODS

REPAIR was a 52-week, open-label, single-arm, multicenter, phase 4 study evaluating the effect of macitentan 10 mg, with or without phosphodiesterase type-5 inhibition, on RV remodeling and function and cardiopulmonary hemodynamics. Primary endpoints were change from baseline to week 26 in RV stroke volume, determined by CMR; and pulmonary vascular resistance, determined by RHC. Efficacy measures were assessed for all patients with baseline and week 26 data for both primary endpoints.

RESULTS

At a prespecified interim analysis in 42 patients, both primary endpoints were met, enrollment was stopped, and the study was declared positive. At final analysis (n = 71), RV stroke volume increased by 12 mL (96% confidence level: 8.4-15.6 mL; P < 0.0001) and pulmonary vascular resistance decreased by 38% (99% confidence level: 31%-44%; P < 0.0001) at week 26. Significant positive changes were also observed in secondary and exploratory CMR (RV and left ventricular), hemodynamic, and functional endpoints at week 26. Improvements in CMR RV and left ventricular variables and functional parameters were maintained at week 52. Safety (n = 87) was consistent with previous clinical trials.

CONCLUSIONS

In the context of this study, macitentan treatment in patients with PAH resulted in significant and clinically-relevant improvements in RV function and structure and cardiopulmonary hemodynamics. At 52 weeks, improvements in RV function and structure were sustained. (REPAIR: Right vEntricular remodeling in Pulmonary ArterIal hypeRtension [REPAIR]; NCT02310672).

Results of a phase I trial to assess the safety of macitentan in combination with temozolomide for the treatment of recurrent glioblastoma

Background

There is an urgent need for additional therapies to treat recurrent glioblastoma (GBM). Preclinical studies suggest that high dose macitentan, an oral dual endothelin receptor antagonist, enhances the cytotoxic effects of temozolomide (TMZ) in GBM, improving survival. This phase I trial investigated the maximum tolerated dose of macitentan combined with TMZ in patients with recurrent GBM and assessed the safety and tolerability of high dose macitentan in these patients (NCT01499251).

Methods

Adults with recurrent GBM received ascending doses of macitentan from 30 mg once daily concomitantly with TMZ. Safety and tolerability were assessed in addition to exploratory efficacy and pharmacokinetic endpoints. An ancillary study examined biomarker expression following macitentan treatment prior to surgical resection of recurrent GBM.

Results

Thirty-eight patients with recurrent GBM were administered macitentan doses up to 300 mg once daily; no dose-limiting toxicities were observed, and a maximum tolerated dose was not determined. All patients experienced at least one treatment-emergent adverse event (TEAE), the majority associated with GBM or TMZ treatment. TEAEs related to macitentan and TMZ were reported for 16 (42.1%) and 26 (68.4%) patients, respectively, with no serious macitentan-related TEAEs. Macitentan concentrations increased with dose, with no plateau in exposure. Substantial heterogeneity was observed in the expression of efficacy biomarkers within tumors. The Kaplan-Meier estimate of median overall survival across all dose groups was 9.4 (95% CI 8.5, 13.4) months.

Conclusion

High-dose macitentan was well tolerated in recurrent GBM patients concomitantly receiving TMZ. TEAEs were consistent with those seen in patients receiving either drug individually.

Primary Human Hepatocyte Spheroids as Tools to Study the Hepatotoxic Potential of Non-Pharmaceutical Chemicals

Drug-induced liver injury, including cholestasis, is an important clinical issue and economic burden for pharmaceutical industry and healthcare systems. However, human-relevant in vitro information on the ability of other types of chemicals to induce cholestatic hepatotoxicity is lacking. This work aimed at investigating the cholestatic potential of non-pharmaceutical chemicals using primary human hepatocytes cultured in 3D spheroids. Spheroid cultures were repeatedly (co-) exposed to drugs (cyclosporine-A, bosentan, macitentan) or non-pharmaceutical chemicals (paraquat, tartrazine, triclosan) and a concentrated mixture of bile acids for 4 weeks. Cell viability (adenosine triphosphate content) was checked every week and used to calculate the cholestatic index, an indicator of cholestatic liability. Microarray analysis was performed at specific time-points to verify the deregulation of genes related to cholestasis, steatosis and fibrosis. Despite the evident inter-donor variability, shorter exposures to cyclosporine-A consistently produced cholestatic index values below 0.80 with transcriptomic data partially supporting its cholestatic burden. Bosentan confirmed to be hepatotoxic, while macitentan was not toxic in the tested concentrations. Prolonged exposure to paraquat suggested fibrotic potential, while triclosan markedly deregulated genes involved in different types of hepatotoxicity. These results support the applicability of primary human hepatocyte spheroids to study hepatotoxicity of non-pharmaceutical chemicals in vitro.

Bioequivalence and food effect of a fixed-dose combination of macitentan and tadalafil: Adaptive design in the COVID-19 pandemic

The COVID‐19 pandemic has forced clinical studies to accommodate imposed limitations. In this study, the bioequivalence part could not be conducted as planned. Thus, the aim was to demonstrate bioequivalence, using an adaptive study design, of tadalafil in fixed‐dose combination (FDC) tablets of macitentan/tadalafil with single macitentan and tadalafil (Canadian‐sourced) tablets and assess the effect of food on FDC tablets in healthy subjects. This Phase 1, single‐center, open‐label, single‐dose, two‐part, two‐period, randomized, crossover study enrolled 62 subjects. Tadalafil bioequivalence as part of FDC of macitentan/tadalafil (10/40 mg) with single‐component tablets of macitentan (10 mg) and tadalafil (40 mg) was determined by pharmacokinetic (PK) assessment under fasted conditions. The effect of food on FDC was evaluated under fed and fasted conditions. Fasted 90% confidence intervals (CIs) for geometric mean ratios (GMRs) were within bioequivalence limits for tadalafil and macitentan. Fed and fasted 90% CIs for area under the curve (AUC) GMR were within bioequivalence limits. However, 90% CIs for maximum plasma concentration (C_max) GMR for macitentan and tadalafil were outside bioequivalence limits. One FDC‐treated subject experienced a serious adverse event of transient ischemic attack (bioequivalence part). To address pandemic‐imposed limitations, an adaptive study design was implemented to demonstrate that the FDC tablet was bioequivalent to the free combination of macitentan and tadalafil (Canadian‐sourced). No clinically significant differences in PK were determined between fed and fasted conditions; the FDC formulation could be taken irrespective of meals. The FDC formulation under fasted and fed conditions was well tolerated with no clinically relevant differences in safety profiles between the treatment groups.

NCT Number: NCT04235270.

Three- Versus Two-Drug Therapy for Patients With Newly Diagnosed Pulmonary Arterial Hypertension

BACKGROUND

In pulmonary arterial hypertension (PAH), there are no data comparing initial triple oral therapy with initial double oral therapy.

OBJECTIVES

TRITON (The Efficacy and Safety of Initial Triple Versus Initial Dual Oral Combination Therapy in Patients With Newly Diagnosed Pulmonary Arterial Hypertension; NCT02558231), a multicenter, double-blind, randomized phase 3b study, evaluated initial triple (macitentan, tadalafil, and selexipag) versus initial double (macitentan, tadalafil, and placebo) oral therapy in newly diagnosed, treatment-naive patients with PAH.

METHODS

Efficacy was assessed until the last patient randomized completed week 26 (end of main observation period). The primary endpoint was change in pulmonary vascular resistance (PVR) at week 26.

RESULTS

Patients were assigned to initial triple (n = 123) or initial double therapy (n = 124). At week 26, both treatment strategies reduced PVR compared with baseline (by 54% and 52%), with no significant difference between groups (ratio of geometric means: 0.96; 95% confidence interval: 0.86-1.07; P = 0.42). Six-minute walk distance and N-terminal pro-brain natriuretic peptide improved by week 26, with no difference between groups. Risk for disease progression (to end of main observation period) was reduced with initial triple versus initial double therapy (hazard ratio: 0.59; 95% confidence interval: 0.32-1.09). Most common adverse events with initial triple therapy included headache, diarrhea, and nausea. By the end of the main observation period, 2 patients in the initial triple and 9 in the initial double therapy groups had died.

CONCLUSIONS

In patients with newly diagnosed PAH, both treatment strategies markedly reduced PVR by week 26, with no significant difference between groups (primary endpoint not met). Exploratory analyses suggested a possible signal for improved long-term outcomes with initial triple versus initial double oral therapy.

Evolution of randomized, controlled studies of medical therapy in chronic thromboembolic pulmonary hypertension

Although pulmonary endarterectomy (PEA) is the treatment of choice for chronic thromboembolic pulmonary hypertension (CTEPH), many patients have inoperable disease, and some have persistent or recurrent pulmonary hypertension (PH) after surgery. Alternative options (balloon pulmonary angioplasty (BPA) and PH-targeted medical therapy) are, therefore, required. Studies of medical therapies for CTEPH have evolved since Aerosolized Iloprost Randomized (AIR), the first randomized, controlled study of a PH-targeted therapy (inhaled iloprost) to include patients with CTEPH. Key learnings from these studies include the need to evaluate CTEPH separately from other types of PH, the importance of prospective operability adjudication as part of the protocol, and the need for sufficient duration to allow treatment benefits to become apparent. The 16-week Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase-Stimulator Study 1 (CHEST-1) study was the first to operationalize these learnings, demonstrating a significant mean improvement in 6-minute walk distance (+46 m) and improvements in hemodynamic endpoints with riociguat versus placebo. Findings from previous studies will inform the design of future studies to address key issues related to combination medical therapy. Data on combinations of macitentan with phosphodiesterase type 5 inhibitors or oral prostanoids are available from MERIT, the first study to allow such regimens. No data on combinations including riociguat, the only licensed medical therapy for CTEPH, are available. Studies are also needed for multimodality treatment, including medical therapy plus BPA, and medical therapy as a bridge to PEA in selected operable patients. To address these issues and improve patient outcomes, it is vital that we learn from current studies to improve future trial design.

Targeting the Endothelin-1 Receptors Curtails Tumor Growth and Angiogenesis in Multiple Myeloma

The endothelin-1 (ET-1) receptors were recently found to mediate pro-survival functions in multiple myeloma (MM) cells in response to autocrine ET-1. This study investigated the effectiveness of macitentan, a dual ET-1 receptor antagonist, in MM treatment, and the mechanisms underlying its activities. Macitentan affected significantly MM cell (RPMI-8226, U266, KMS-12-PE) survival and pro-angiogenic cytokine release by down-modulating ET-1-activated MAPK/ERK and HIF-1α pathways, respectively. HIF-1α silencing abrogated the ET-1 mediated induction of genes encoding for pro-angiogenic cytokines such as VEGF-A, IL-8, Adrenomedullin, and ET-1 itself. Upon exposure to macitentan, MM cells cultured in the presence of the hypoxia-mimetic agent CoCl₂, exogenous ET-1, or CoCl₂ plus ET-1, down-regulated HIF-1α and the transcription and release of downstream pro-angiogenic cytokines. Consistently, macitentan limited significantly the basal pro-angiogenic activity of RPMI-8226 cells in chorioallantoic membrane assay. In xenograft mouse models, established by injecting NOG mice either via intra-caudal vein with U266 or subcutaneously with RPMI-8226 cells, macitentan reduced effectively the number of MM cells infiltrating bone marrow, and the size and microvascular density of subcutaneous MM tumors. ET-1 receptors targeting by macitentan represents an effective anti-proliferative and anti-angiogenic therapeutic approach in preclinical settings of MM.

Effects of macitentan and tadalafil monotherapy or their combination on the right ventricle and plasma metabolites in pulmonary hypertensive rats

Pulmonary arterial hypertension is a severe respiratory disease characterized by pulmonary artery remodeling. RV dysfunction and dysregulated circulating metabolomics are associated with adverse outcomes in pulmonary arterial hypertension. We investigated effects of tadalafil and macitentan alone or in combination on the RV and plasma metabolomics in SuHx and PAB models. For SuHx model, rats were injected with SU5416 and exposed to hypoxia for three weeks and then were returned to normoxia and treated with either tadalafil (10 mg/kg in chow) or macitentan (10 mg/kg in chow) or their combination (both 10 mg/kg in chow) for two weeks. For PAB model, rats were subjected to either sham or PAB surgery for three weeks and treated with above-mentioned drugs from week 1 to week 3. Following terminal echocardiographic and hemodynamic measurements, tissue samples were collected for metabolomic, histological and gene expression analysis. Both SuHx and PAB rats developed RV remodeling/dysfunction with severe and mild plasma metabolomic alterations, respectively. In SuHx rats, tadalafil and macitentan alone or in combination improved RV remodeling/function with the effects of macitentan and combination therapy being superior to tadalafil. All therapies similarly attenuated SuHx-induced changes in plasma metabolomics. In PAB rats, only macitentan improved RV remodeling/function, while only tadalafil attenuated PAB-induced changes in plasma metabolomics.

Safety of macitentan in sarcoidosis-associated pulmonary hypertension: a case-series

Background:

Pulmonary hypertension (PH) is a known complication of pulmonary sarcoidosis and is associated with higher morbidity and mortality. Currently, there are no approved PH-targeted therapies for sarcoidosis-associated pulmonary hypertension (SAPH). Macitentan is frequently used as treatment for pulmonary arterial hypertension, but no results are known in the SAPH population.

Objective:

We investigated the safety and effect of macitentan as treatment for SAPH.

Methods:

We retrospectively reviewed our patient database for all SAPH patients receiving macitentan as treatment, with a minimum follow-up of twelve months for monitoring safety. Safety outcomes included reported side-effects, hospitalisations and mortality. Furthermore, six-minutes walking distance, New York Heart Association functional class and NT-proBNP levels were collected.

Results:

Six cases (three men) with a median age of 64 years (range 52-74 years) were identified. During macitentan treatment, one patient experienced side effects and aborted therapy after five days of treatment and died 16 months later. Three patients were hospitalised during treatment for congestive heart failure. Four patients showed improvement of their functional class and three patients in exercise capacity after 12 months of therapy.

Conclusion:

Macitentan was well tolerated in five out of six cases with severe pulmonary sarcoidosis and PH. Functional capacity improved in four cases. Prospective controlled trials are warranted before therapeutic recommendations can be made. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (1): 74-78)

Safety and efficacy of the endothelin receptor antagonist macitentan in pediatric pulmonary hypertension

Background

Macitentan, a dual endothelin receptor antagonist (ERA), was approved in 2014 for the treatment of adults with idiopathic pulmonary arterial hypertension (PAH). Once-per-day dosing and low potential hepatic toxicity make macitentan an appealing therapeutic option for children with PAH, but reports on its use in pediatric patients are still lacking.

Methods

Prospective observational study of 18 children [10 male; median age: 8.5, minimum (min.): 0.6, maximum (max.): 16.8 years] with pulmonary hypertension (PH). Four of these 18 patients were treatment-naïve and started on a de novo macitentan therapy. The remaining 14/18 children were already on a PH-targeted pharmacotherapy (sildenafil or bosentan as monotherapy or in combination). Nine children who were on bosentan were switched to macitentan. We analyzed the 6-minute walking distance (6MWD), NYHA functional class (FC)/modified ROSS score, invasive hemodynamics, echocardiographic variables and the biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP).

Results

The median follow up was 6 months (min.: 0.5, max.: 30). Macitentan treatment was associated with improvement of invasive hemodynamics, e.g., the ratio of mean pulmonary arterial pressure/mean systemic arterial pressure decreased from a median of 62% (min.: 30%, max.: 87%) to 49% (min.: 30%, max.: 69%), P<0.05; pulmonary vascular resistance index (PVRi) decreased from a median of 7.6 (min.: 3.3, max.: 11.5) to 4.8 Wood units × m² body surface area (min.: 2.5, max.: 10), P<0.05. The tricuspid annular plane systolic excursion (TAPSE) increased from a median of 1.4 (min.: 0.8, max.: 2.8) to 1.9 (min.: 0.8, max.: 2.7) cm, (P<0.05). NT-proBNP values decreased from a median of 272 (min.: 27, max.: 2,010) to 229 (min.: 23, max.: 814) pg/mL under macitentan therapy (P<0.05). The 6MWD and NYHA FC/modified ROSS score did not change significantly.

Conclusions

This is the first prospective study of macitentan pharmacotherapy in infants and children with PH <12 years of age. Except in one patient, macitentan treatment was well tolerated and was associated with improvements in invasive hemodynamics, longitudinal systolic RV function (TAPSE) and serum NT-proBNP values.

Influence of Macitentan on the Vascular Tone and Recruitment of Finger Capillaries Under Hypobaric Hypoxia in High Altitude

Betge, Stefan, Stefan Drinda, Thomas Neumann, Laura Bäz, Alexander Pfeil, Christian Schulze, Ralf Mrowka, Christian Jung, and Marcus Franz. Influence of macitentan on the vascular tone and recruitment of finger capillaries under hypobaric hypoxia in high altitude. High Alt Med Biol. 21:336-345, 2020. Introduction: Acute normobaric (NH) and hypobaric hypoxia (HH) has effects on the vascular tone of larger arteries and may have effects on the microcirculation. These effects may be noninvasively detectable by automated devices. A part of these effects may be mediated by endothelin (ET) and should be influenced by macitentan (MAC), a dual endothelin receptor antagonist (ERA). Methods: We used photoplethysmographic sensors, fingertip volume sensors, nailfold capillaroscopy, and laser Doppler probes at rest and after a 5-minute forearm ischemia in healthy study subjects under NH, under HH, and under HH plus a single dose of MAC. Results: NH at simulated 4000 m led to increased heart rates (HR) and pulse wave velocities (PWV) and reduced augmentation index (AIX). The values for the AIX showed a high SD and differed between the used devices. At simulated 5500 m, only baseline mean value (BMV; EndoPAT) showed a further change, indicating less filled capillaries of the fingertips. HH (2978 m) increased HR, blood pressure values, and PWV. Focusing on the microcirculation of the fingertips, HH reduced the BMV and the nailfold capillary density and the postischemic capillary recruitment. MAC had no effect on the BMV, but antagonized the effects of HH on the nailfold capillaries and led to a strongly increased postischemic diameter of the arterial limbs. Concordantly, the postischemic blood flow velocity increment, measured through ultrasound Doppler, was increased at ALT+MAC. Conclusions: The BMV may be a parameter for changes of the microcirculation of the finger tips. A single dose of MAC blocked hypoxia-induced capillary rarefaction and enhanced postischemic hyperemia of the fingertips. These results indicate the importance of ET-1 for the regulation of the microcirculation under hypoxia. The German Registry of Clinical Studies (DRKS) ID: 00005459.

The endothelin receptor antagonist macitentan for the treatment of pulmonary arterial hypertension: A cross-species comparison of its cytochrome P450 induction pattern

The dual endothelin receptor antagonist macitentan was approved in 2013 for the treatment of pulmonary arterial hypertension. Macitentan is an inducer of cytochrome P450 expression in vivo in animal species but not in man. In rat and dog, changes in P450 expression manifest as autoinduction upon repeat dosing. The induction pattern, however, significantly differed between both species, and between male and female rats. While macitentan exposure steadily declined with dose in the dog, P450 induction was saturable in the rat reaching levels of 40%-60% and 60%-80% at steady-state in male and female animals, respectively. The nature and number of P450 enzymes involved in macitentan clearance were identified as a major reason for the observed species differences. In the dog, macitentan was metabolized by a single P450 enzyme, that is, Cyp3a12, whereas several members of the Cyp2c and Cyp3a families were involved in the rat. Macitentan selectively upregulated Cyp3a expression in rat, whereas the expression of the Cyp2c enzymes involved in macitentan metabolism remained mostly unchanged, eventually leading to a higher contribution of Cyp3a upon induction. Macitentan also induced CYP3A4 expression in human hepatocytes via initial activation of the human pregnane X receptor. No such induction was evident in humans at the therapeutic macitentan dose of 10 mg as shown in a clinical drug-drug interaction study with the CYP3A4 substrate sildenafil.

Macitentan in the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is an uncommon but lethal and progressive disease in which prostacyclin, nitric oxide and endothelin-1 pathways are disturbed and contribute to the pathophysiology of this disease. Endothelin receptor antagonists are a class of drugs that have been approved as PAH therapy. Macitentan is a lipophilic, tissue specific, dual receptor antagonist with a higher potency than bosentan and a reduced risk of hepatic injury. Macitentan has shown a reduction in morbidity and mortality due to PAH at long-term follow-up and improvements in hemodynamics, exercise capacity and functional class at the short term. Its main adverse events are nasopharyngitis, bronchitis and an increased risk of anemia. We review the clinical data of macitentan and its use in PAH.

Long-term treatment of pulmonary arterial hypertension with macitentan in Japanese patients

Objective: Macitentan, a novel dual endothelin receptor antagonist, was approved for the treatment of pulmonary arterial hypertension (PAH) in Japan. However, long-term effects in Japanese patients of macitentan are currently unavailable. This study sought to assess the long-term efficacy and safety of macitentan in Japanese patients with PAH.Methods: In this multicenter, open-label, clinical extension study (JapicCTI-121986), efficacy was evaluated based on the change from baseline at 24, 48, 72, 96 and 120-week in the 6-minute walk distance (6MWD), World Health Organization (WHO) functional class, and serum N-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels. In addition, the time to a hospitalization related to PAH and a morbidity/mortality event was determined. As for safety, the incidence of adverse events and changes in laboratory data and vital signs were assessed.Results: Macitentan was administered at a once-daily dose of 10 mg in 30 PAH patients with a median treatment period of 2.4 years (range, 229-1037 days). The improvements in 6MWD, WHO functional class and NT-pro-BNP at week 24 were maintained throughout the long-term follow-up. Hospitalization related to PAH occurred in 2 patients. Levels of liver enzyme and hemoglobin remained unchanged throughout the study period.Conclusions: This study suggests that the long-term use of macitentan is well tolerated and effective in Japanese patients with PAH. We concluded that macitentan can be a possible approach to reduce morbidity/mortality in Japanese PAH patients.

Integrating Data From Randomized Controlled Trials and Observational Studies to Assess Survival in Rare Diseases

Supplemental Digital Content is available in the text.

Background:

Conducting randomized controlled trials to investigate survival in a rare disease like pulmonary arterial hypertension has considerable ethical and logistical constraints. In many studies, such as the Study with an Endothelin Receptor Antagonist in Pulmonary Arterial Hypertension to Improve Clinical Outcome (SERAPHIN) randomized controlled trial, evaluating survival is further complicated by bias introduced by allowing active therapy among placebo-treated patients who clinically deteriorate.

Methods and Results:

SERAPHIN enrolled and followed patients in the same time frame as the US Registry to Evaluate Early And Long-term PAH Disease Management, providing an opportunity to compare observed survival for SERAPHIN patients with predicted survival had they received real-world treatment as in the Registry to Evaluate Early And Long-term PAH Disease Management. From the Registry to Evaluate Early And Long-term PAH Disease Management (N=3515), 734 patients who met SERAPHIN eligibility criteria were selected and their data used to build a prediction model for time to death up to 3 years based on 10 baseline prognostic variables. The model was used to predict a survival curve for each of the 742 SERAPHIN patients via their baseline variables. The average of these predicted survival curves was compared with observed survival of the placebo (n=250) and macitentan 10 mg (n=242) groups using a log-rank test and Cox proportional hazard model. Observed mortality risk for patients randomized to placebo, 62% of whom were taking background pulmonary arterial hypertension therapy, tended to be lower than that predicted for all SERAPHIN patients (16% lower; P=0.259). The observed placebo survival curve closely approximated the predicted survival curve for the first 15 months. Beyond that time, observed risk of mortality decreased compared with predicted mortality, potentially reflecting the impact of crossover of patients in the placebo group to active therapy. Over 3 years, risk of mortality observed with macitentan 10 mg was 35% lower than predicted mortality (P=0.010).

Conclusions:

These analyses show that, in a rare disease, real-world observational data can complement randomized controlled trial data to overcome some challenges associated with assessing survival in the setting of a randomized controlled trial.

Clinical Trial Registration:

https://www.clinicaltrials.gov. Unique identifiers: NCT00660179 and NCT00370214.

Bioequivalence of macitentan and tadalafil given as fixed-dose combination or single-component tablets in healthy subjects

Aims

To demonstrate the bioequivalence of macitentan/tadalafil fixed‐dose combination (FDC) tablets with single‐component tablets of macitentan and tadalafil in healthy subjects.

Methods

Studies AC‐077‐101 and AC‐077‐103 were single‐centre, open‐label, single‐dose, 2‐period, randomized, crossover Phase 1 studies conducted in healthy subjects. Two FDCs were investigated: FDC‐1 and FDC‐2 in Study AC‐077‐101 and FDC‐2 in Study AC‐077‐103. Both FDCs contained 10 mg/40 mg of macitentan/tadalafil and differed in excipients and coating materials used. In both studies, pharmacokinetic sampling over 216 hours was conducted, and pharmacokinetic parameters were derived using noncompartmental methods.

Results

Bioequivalence of macitentan, its active metabolite ACT‐132577, and tadalafil was established for FDC‐2 in both studies AC‐077‐101 and AC‐077‐103 in which tadalafil as a single component was sourced from the USA and EU, respectively, to fulfil regional regulatory requirements. The area under the plasma concentration–time curve and maximum plasma concentration with 90% confidence intervals of all components were entirely within the bioequivalence limits (0.8000–1.2500). No subject died and no serious adverse events were reported in either studies.

Conclusion

The FDC‐2 tablet containing 10 mg/40 mg of macitentan/tadalafil was bioequivalent to the free combination of 10 mg macitentan and 40 mg tadalafil (both US and EU sourced). Macitentan and tadalafil were well tolerated when administered as FDC or as a free combination.

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

BACKGROUND

Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term study.

AIM

We have recently reported that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension in a 24-week prospective study and well tolerated without adverse events. We now aimed to evaluate clinical efficacy, safety of switch in a larger patient population, in a 24-month prospective study.

METHODS

This is a single-institution, 24-month prospective study. Patients ≥12 years with idiopathic/heritable, pulmonary arterial hypertension, or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan treatment were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors/inhaled prostanoids was allowed. Outcome measures included change from baseline to 24 months, in the 6-minute walk distance, functional class, oxygen saturation at rest/after walk distance test, and natriuretic peptide levels. Safety end points included adverse events, laboratory abnormalities.

RESULTS

Twenty-seven patients (19 adults/8 children, mean age: 21.1 ± 6.3 years (12-36), weight: 53.1 ± 15.7 kgs (26-87)) were included. Mean duration of macitentan treatment: 22.3 ± 3.9 months (9-24). Six-minute walk distance significantly improved from baseline (mean: 458 ± 79 m (300-620)) at 6 months (mean: 501 ± 73 m (325-616) + 43 m) (p < 0.05), at 12 months (mean: 514 ± 82 m (330-626) + 56 m) (p < 0.05), and at 24 months (mean: 532 ± 85 m (330-682) + 74 m) (p < 0.05). We observed a significant improvement during the first 6 months but no incremental improvement after 6 months (p > 0.05). Macitentan did not significantly change functional class, oxygen saturation, and natriuretic levels (p > 0.05). None of the patients had anaemia, hepatotoxicity, and peripheral edema.

CONCLUSIONS

Our study is the first study which showed that switch from bosentan to macitentan improved exercise capacity in children and young adults with pulmonary arterial hypertension significantly in the first 6 months and compared to baseline in 24 months and well tolerated without adverse events.

PK/PD modeling based on NO-ET homeostasis for improving management of sunitinib-induced hypertension in rats

Sunitinib is an oral small molecule multitargeted tyrosine kinase inhibitor, which is currently used to treat severe cancers. Clinical research has shown that patients treated with sunitinib develop hypertension. As soon as sunitinib-induced hypertension appears, it is usual to administer anti-hypertension agent. But this treatment may cause acute blood pressure fluctuation which may lead to additional cardiovascular risk. The aim of this study is to establish a mathematical model for managing sunitinib-induced hypertension and blood pressure fluctuation. A mechanism-based PK/PD model was developed based on animal experiments. Then this model was used to perform simulations, thus to propose an anti-hypertension indication, according to which the anti-hypertension treatment might yield relative low-level AUC and fluctuation of blood pressure. The simulation results suggest that the anti-hypertension agent may yield low-level AUC and fluctuation of blood pressure when relative ET-1 level ranges from −15% to 5% and relative NO level is more than 10% compared to control group. Finally, animal experiments were conducted to verify the simulation results. Macitentan (30 mg/kg) was administered based on the above anti-hypertension indication. Compared with the untreated group, the optimized treatment significantly reduced the AUC of blood pressure; meanwhile the fluctuation of blood pressure in optimized treatment group was 70% less than that in immediate treatment group. This work provides a novel model with potential translational value for managing sunitinib-induced hypertension.

Endothelin Receptor Antagonists: Status Quo and Future Perspectives for Targeted Therapy

The endothelin axis, recognized for its vasoconstrictive action, plays a central role in the pathology of pulmonary arterial hypertension (PAH). Treatment with approved endothelin receptor antagonists (ERAs), such as bosentan, ambrisentan, or macitentan, slow down PAH progression and relieves symptoms. Several findings have indicated that endothelin is further involved in the pathogenesis of certain other diseases, making ERAs potentially beneficial in the treatment of various conditions. In addition to PAH, this review summarizes the use and perspectives of ERAs in cancer, renal disease, fibrotic disorders, systemic scleroderma, vasospasm, and pain management. Bosentan has proven to be effective in systemic sclerosis PAH and in decreasing the development of vasospasm-related digital ulcers. The selective ERA clazosentan has been shown to be effective in preventing cerebral vasospasm and delaying ischemic neurological deficits and new infarcts. Furthermore, in the SONAR (Study Of Diabetic Nephropathy With Atrasentan) trial, the selective ERA atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease. These data suggest atrasentan as a new therapy in the treatment of diabetic nephropathy and possibly other renal diseases. Preclinical studies regarding heart failure, cancer, and fibrotic diseases have demonstrated promising effects, but clinical trials have not yet produced measurable results. Nevertheless, the potential benefits of ERAs may not be fully realized.

Evaluation of Macitentan in Patients With Eisenmenger Syndrome

Supplemental Digital Content is available in the text.

Background:

Eisenmenger syndrome describes congenital heart disease-associated severe pulmonary hypertension accompanied by right-to-left shunting. The multicenter, double-blind, randomized, placebo-controlled, 16-week, phase III MAESTRO study (Macitentan in Eisenmenger Syndrome to Restore Exercise Capacity) evaluated the efficacy and safety of the endothelin receptor antagonist macitentan in patients with Eisenmenger syndrome.

Methods:

Patients with Eisenmenger syndrome aged ≥12 years and in World Health Organization functional class II–III were randomized 1:1 to placebo or macitentan 10 mg once daily for 16 weeks. Patients with complex cardiac defects, Down syndrome and background PAH therapy were eligible. The primary end point was change from baseline to week 16 in 6-minute walk distance. Secondary end points included change from baseline to week 16 in World Health Organization functional class. Exploratory end points included NT-proBNP (N-terminal pro-B-type natriuretic peptide) at end of treatment expressed as a percentage of baseline. In a hemodynamic substudy, exploratory end points included pulmonary vascular resistance index (PVRi) at week 16 as a percentage of baseline.

Results:

Two hundred twenty six patients (macitentan n=114; placebo n=112) were randomized. At baseline, 60% of patients were in World Health Organization functional class II and 27% were receiving phosphodiesterase type-5 inhibitors. At week 16, the mean change from baseline in 6-minute walk distance was 18.3 m and 19.7 m in the macitentan and placebo groups (least-squares mean difference, -4.7 m; 95% confidence limit (CL), -22.8, 13.5; P=0.612). World Health Organization functional class improved from baseline to week 16 in 8.8% and 14.3% of patients in the macitentan and placebo groups (odds ratio, 0.53; 95% CL, 0.23, 1.24). NT-proBNP levels decreased with macitentan versus placebo (ratio of geometric means, 0.80; 95% CL, 0.68, 0.94). In the hemodynamic substudy (n=39 patients), macitentan decreased PVRi compared with placebo (ratio of geometric means, 0.87; 95% CL, 0.73, 1.03). The most common adverse events with macitentan versus placebo were headache (11.4 versus 4.5%) and upper respiratory tract infection (9.6 versus 6.3%); a hemoglobin decrease from baseline of ≥2 g/dL occurred in 36.0% versus 8.9% of patients. Five patients (3 macitentan; 2 placebo) prematurely discontinued treatment and 1 patient died (macitentan group).

Conclusions:

Macitentan did not show superiority over placebo on the primary end point of change from baseline to week 16 in exercise capacity in patients with Eisenmenger syndrome.

Clinical Trial Registration:

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01743001.

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.

Pharmacotherapy for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a condition associated with substantial morbidity and mortality. Over the last 25 years there has been a significant evolution in the therapies to treat PAH. These therapies are effective for patients with group I PAH and group IV PH [chronic thromboembolic pulmonary hypertension (CTEPH)]. PAH is characterized by an imbalance of nitric oxide, prostacyclin and endothelin levels, and current pharmacotherapy involves these three pathways. Earlier clinical trials involving PAH-specific therapies evaluated improvements in 6-minute walk time as a primary improvement whereas contemporary trials have been larger and focused on morbidity and mortality reductions. While there may be a role for monotherapy in disease management, most patients should be considered for dual or triple therapy.

Treatment of pulmonary arterial hypertension with the dual endothelin receptor antagonist macitentan: clinical evidence and experience

Macitentan (10 mg once daily orally), a dual endothelin receptor antagonist (ERA) developed by modifying the structure of bosentan to increase the efficacity and safety, is approved for the treatment of pulmonary arterial hypertension (PAH). The pivotal SERAPHIN trial, (a landmark trial in the history of PAH trials because of the large number of included patients, the long-term follow up and the first trial with morbidity/mortality as the primary endpoint) showed a reduction of the risk of a morbidity or mortality event by 45% over the treatment time compared with placebo. The positive effect on the primary endpoint was observed whether or not the patient was already on PAH therapy. There has been no direct comparison between macitentan and other ERAs, which were approved based on improved exercise capacity, but preclinical and clinical data suggest better pharmacological and safety profiles. Further analyses of the SERAPHIN trial investigated the predictive value of different indices and events on long-term outcome and mortality. The efficacy in children, the long-term effects and safety of macitentan and its place in combination therapy compared with other ERAs are still under investigation. This review presents the preclinical evidence of superiority of macitentan compared with other ERAs, and the available clinical trial data. The place of macitentan in the therapeutic algorithm for PAH treatment, post-marketing experience and future perspectives are discussed.

Combination Therapy in Pulmonary Arterial Hypertension: Gleaning a Practical Approach from the Randomized Trials

In the past decade, combination therapy in pulmonary arterial hypertension (PAH) has evolved from something PAH practitioners felt almost compelled to do, notwithstanding the absence of data, to a strategy proven by well-conducted randomized clinical trials. Whereas in the past, PAH treatment was limited to parenteral epoprostenol; today multiple drugs administrable either parenterally, inhaled, or orally have expanded the options for treating PAH patients. The SERIPHIN, AMBITION, and GRIPHON trials and emerging findings in FREEDOM-EV confirm the validity of a combined-therapy approach. Data from these trials in which either combined therapy was planned or an agent was added to background therapy have demonstrated significant reduction in the progression of disease and are on the cusp of demonstrating survival benefit. Combination therapy may be started simultaneously in some cases, but in many cases a stepped approach to initiating a second, or third, agent is better tolerated. Trials of all the specific combinations of drugs may not be possible, but a continuing trend toward treating PAH with multiple agents is likely. Currently, Food and Drug Administration-approved agents are predominantly pulmonary vasodilators acting through different pathways, with minimal impact on progression of the proliferative pulmonary arteriopathy that is the key pathologic finding in PAH. It is to be hoped that treatment strategies that result in halting progression and substantial reversal of pulmonary arteriolar obstruction will soon be discovered and available.

Pulmonary arterial hypertension outcomes upon endothelin-1 receptor antagonist switch to macitentan

OBJECTIVES

To assess whether switching patients with suboptimally controlled pulmonary arterial hypertension from bosentan or ambrisentan to macitentan would improve six-minute walk test (6MWT) distance and World Health Organization functional class.

METHODS

This was a retrospective cohort analysis of 37 patients from a single center. Patients were separated into three heterogeneous treatment groups and followed for 18 months: switch group (n = 14): patients switched to macitentan from bosentan/ambrisentan; added group (n = 11): patients who began macitentan as de novo therapy (n = 5) or who added macitentan to an existing sildenafil regimen (n = 6); and control group (n = 12): patients for whom sildenafil and/or bosentan/ambrisentan therapy was unchanged.

RESULTS

Mortality was observed in two patients (one each, switch and added groups). Patients in the control group had one hospital admission and 100% survival. There was significant improvement in functional class for the switch and added groups. Statistically significant improvement was observed in 6MWT distance in the added group alone. Overall, 92% of patients continued macitentan throughout the study.

CONCLUSION

Macitentan was well tolerated. For bosentan/ambrisentan-treated patients with suboptimally controlled pulmonary arterial hypertension, switching to macitentan may facilitate an improvement in functional class.

A dual blocker of endothelin A/B receptors mitigates hypertension but not renal dysfunction in a rat model of chronic kidney disease and sleep apnea

Obstructive sleep apnea is characterized by recurrent episodes of pharyngeal collapse during sleep, resulting in intermittent hypoxia (IH), and is associated with a high incidence of hypertension and accelerated renal failure. In rodents, endothelin (ET)-1 contributes to IH-induced hypertension, and ET-1 levels inversely correlate with glomerular filtration rate in patients with end-stage chronic kidney disease (CKD). Therefore, we hypothesized that a dual ET receptor antagonist, macitentan (Actelion Pharmaceuticals), will attenuate and reverse hypertension and renal dysfunction in a rat model of combined IH and CKD. Male Sprague-Dawley rats received one of three diets (control, 0.2% adenine, and 0.2% adenine + 30 mg·kg^-1·day^-1 macitentan) for 2 wk followed by 2 wk of recovery diet. Rats were then exposed for 4 wk to air or IH (20 short exposures/h to 5% O₂-5% CO₂ 7 h/day during sleep). Macitentan prevented the increases in mean arterial blood pressure caused by CKD, IH, and the combination of CKD + IH. However, macitentan did not improve kidney function, fibrosis, and inflammation. After CKD was established, rats were exposed to air or IH for 2 wk, and macitentan feeding continued for 2 more wk. Macitentan reversed the hypertension in IH, CKD, and CKD + IH groups without improving renal function. Our data suggest that macitentan could be an effective antihypertensive in patients with CKD and irreversible kidney damage as a way to protect the heart, brain, and eyes from elevated arterial pressure, but it does not reverse toxin-induced tubule atrophy.