Efficacy, safety, and pharmacokinetics of ambrisentan in Japanese adults with pulmonary arterial hypertension

Contribution of pressure and flow changes to resistance reduction after pulmonary arterial hypertension treatment: a meta-analysis of 3898 patients

Background

Pulmonary arterial hypertension (PAH)-targeted therapies exert significant haemodynamic changes; however, systematic synthesis is currently lacking.

Methods

We searched PubMed, CENTRAL and Web of Science for studies evaluating mean pulmonary artery pressure (mPAP), cardiac index/cardiac output (CI/CO) and pulmonary vascular resistance (PVR) of PAH-targeted therapies either in monotherapy or combinations as assessed by right heart catheterisation in treatment-naïve PAH patients. We performed a random-effects meta-analysis with meta-regression.

Results

We included 68 studies (90 treatment groups) with 3898 patients (age 47.4±13.2 years, 74% women). In studies with small PVR reduction (<4 WU), CI/CO increase (R2=62%) and not mPAP reduction (R2=24%) was decisive for the PVR reduction (p<0.001 and p=0.36, respectively, in the multivariable meta-regression model); however, in studies with large PVR reduction (>4 WU), both CI/CO increase (R2=72%) and mPAP reduction (R2=35%) contributed significantly to the PVR reduction (p<0.001 and p=0.01, respectively). PVR reduction as a percentage of the pre-treatment value was more pronounced in the oral+prostanoid intravenous/subcutaneous combination therapy (mean difference -50.0%, 95% CI -60.8- -39.2%), compared to oral combination therapy (-41.7%, -47.6- -35.8%), prostanoid i.v./s.c. monotherapy (-31.8%, -37.6- -25.9%) and oral monotherapy (-21.6%, -25.4- -17.8%). Changes in haemodynamic parameters were significantly associated with changes in functional capacity of patients with PAH as expressed by the 6-min walking distance.

Conclusion

Combination therapies, especially with the inclusion of parenteral prostanoids, lead to remarkable haemodynamic improvement in treatment-naïve PAH patients and may unmask the contribution of mPAP reduction to the overall PVR reduction in addition to the increase in CO.

Comparative assessment of efficacy and safety of ambrisentan and bosentan in patients with pulmonary arterial hypertension: A meta-analysis

WHAT IS KNOWN AND OBJECTIVE

Two endothelin receptor antagonists, ambrisentan and bosentan, have been demonstrated to be effective individually compared with placebo in the treatment of patients with pulmonary arterial hypertension (PAH). This network meta-analysis compared the efficacy and safety of ambrisentan and bosentan in patients with PAH.

METHODS

Clinical trials were identified from the Cochrane Central Register of Controlled Trials (CENTRAL/CCTR), EMBASE and PubMed databases. Weighted mean differences (MD) with 95% confidence intervals (CI) were calculated for continuous outcomes (6-min walk distance [6MWD] and Borg dyspnoea index [BDI]). Hazard ratio (HR) was calculated for binary outcomes, including clinical worsening, discontinuation due to adverse events (AEs) and liver dysfunction. Surface under cumulative ranking curve (SUCRA) was used to rank the treatments in each index.

RESULTS

Five clinical trials from four published studies (total patients: n = 920) were included. Ambrisentan and bosentan showed no significant difference in 6MWD (MD: -1.32; 95% CI: -27.87, 25.31, SUCRA score: ambrisentan 0.73, bosentan 0.77), BDI (MD: -0.16; 95% CI: -0.98, 0.65, SUCRA score: ambrisentan 0.83, bosentan 0.66), clinical worsening (HR: 0.99; 95% CI: 0.33, 2.94, SUCRA score: ambrisentan 0.75, bosentan 0.74) and discontinuation due to AEs (HR: 0.84; 95% CI: 0.11, 5.86, SUCRA score: ambrisentan 0.47, bosentan 0.57). However, ambrisentan was significantly better than bosentan with respect to abnormal liver function (HR: 23.18; 95% CI: 2.24, 377.20, SUCRA score: ambrisentan 0.99, bosentan 0.02).

WHAT IS NEW AND CONCLUSION

The results of this network meta-analysis suggest that ambrisentan was similar to bosentan in efficacy, while it exhibited better tolerability with respect to abnormal liver function in comparison with bosentan, in patients with PAH.

A Randomized, Controlled Pharmacokinetic and Pharmacodynamics Trial of Ambrisentan After Fontan Surgery

OBJECTIVES

To determine the pharmacokinetics, pharmacodynamics, and safety of the hepatically metabolized endothelin receptor antagonist, ambrisentan in children after Fontan surgery.

DESIGN

Prospective, randomized, double-blind, placebo-controlled pharmacokinetic/pharmacodynamics and safety trial.

SETTING

Single-center, postoperative cardiac ICU.

PATIENTS

Children undergoing elective Fontan surgery.

INTERVENTIONS

Subjects randomized on postoperative day number 1 to short-term (3 d) treatment with oral ambrisentan (2.5 mg in suspension, daily) versus placebo (4:1 randomization).

MEASUREMENTS AND MAIN RESULTS

Plasma drug concentrations were measured at 0.5, 1, 2, 4, and 18-36 hours after the first dose. We developed a population pharmacokinetic model in NONMEM 7.2 (Icon Solutions, Ellicott City, MD) and applied the model to dose-exposure simulations. Pharmacodynamics endpoints were assessed at baseline and 3 hours after study drug administration, using postoperative hemodynamic monitoring lines. The analysis included 16 patients, 13 on ambrisentan (77 plasma samples); median age 36 months (range, 26-72 mo), weight 13.3 kg (11.1-17.6 kg), and nine males. There were no differences in baseline characteristics between ambrisentan and controls. A one-compartment model with first-order absorption and lag-time characterized the data well. Allometrically scaled weight was the only covariate retained in the final model. Typical values for clearance and volume of distribution were lower than previously reported in adults, 1 L/hr/70 kg and 13.7 L/70 kg, respectively. Simulated exposures with doses of 0.1-0.2 mg/kg approximated therapeutic exposures in adults with pulmonary arterial hypertension receiving 5 mg or 10 mg doses. Ambrisentan lowered plasma brain natriuretic peptide concentrations (452 ± 479 to 413 ± 462; p = 0.046), Fontan pressures (16.8 ± 2.9 to 15.6 ± 2.9; p = 0.01), and indexed pulmonary vascular resistance (2.3 ± 0.9 to 1.8 ± 0.6; p = 0.01) with no drug-related adverse events.

CONCLUSIONS

Ambrisentan clearance is reduced following Fontan surgery, perhaps reflecting abnormal hepatic metabolism in this population. The observed safety profile appears favorable and hemodynamic effects of ambrisentan may be beneficial for Fontan patients.

Safety and Efficacy of Ambrisentan-Phosphodiesterase Type 5 (PDE5) Inhibitor Combination Therapy for Japanese Pulmonary Arterial Hypertension Patients in Real-World Clinical Practice

Background: This retrospective study was conducted to evaluate the safety and efficacy of ambrisentan combination therapy with phosphodiesterase type 5 (PDE5) inhibitors in Japanese patients with pulmonary arterial hypertension (PAH).

Methods and Results: PAH patients who received ambrisentan for the first time in combination with a PDE5 inhibitor between January 2013 and the end of August 2015 were included in this study. Adverse drug reaction (ADR) safety analysis, as well as the efficacy analysis focusing on changes in clinical parameters, were investigated for overall cases and cases stratified by patient background. Forty-eight consecutive patients (n=21, 43.8% with idiopathic PAH; male/female, 18/30; average age, 43.3±17.4 years; World Health Organization functional class III/IV, n=22, 45.8%) who were treated with ambrisentan and a PDE5 inhibitor in Japan underwent the safety analysis. A total of 14 ADR occurred in 10 patients (20.8%). ADR included headache (8.3%), face edema (4.2%), angina pectoris (2.1%), hyperemia (2.1%), dyspnea (2.1%), pulmonary hypertension (i.e., worsening of PAH, 2.1%), nausea (2.1%), hepatic function abnormal (2.1%), edema (2.1%), and sudden death (2.1%). On analysis of hemodynamics parameters, there was a significant improvement in the mean pulmonary arterial pressure (−13.5 mmHg, P=0.0001) and pulmonary vascular resistance (−563.53 dyn·s·cm⁻⁵, P=0.0033).

Conclusions: Ambrisentan combination therapy is safe and effective in hemodynamics improvement.

Surveillance on The Safety and Efficacy of Ambrisentan (Volibris Tablet 2.5 mg) in Patients with Pulmonary Arterial Hypertension in Real Clinical Practice: Post-marketing Surveillance (Interim Analysis Report)

BACKGROUND AND OBJECTIVE

Pulmonary arterial hypertension (PAH) is an intractable and rare disease and the accumulation of clinical evidence under real-world setting is needed. A post-marketing surveillance for the endothelin receptor antagonist ambrisentan (Volibris tablet) has been conducted by all-case investigation since September 2010. This paper is an interim report on the safety and efficacy of ambrisentan in 702 patients with PAH.

METHODS

PAH patients aged 15 years or older were subjected to the analysis. The safety analysis by overall cases or stratification of patient backgrounds and the efficacy analysis were investigated.

RESULTS

Regarding patient characteristics, the 702 patients subjected to safety analysis included 543 (77.4%) women and 546 (77.8%) patients at WHO functional class II/III. The mean observational time was 392.7 days. A total of 324 adverse drug reaction (ADR) occurred in 204 (29.1%) patients. Common ADRs (≥ 2%) included anemia (4.6%), peripheral edema (4.1%), headache (3.6%), edema and face edema (2.6% each), abnormal hepatic function (2.3%), and epistaxis (2.1%). There were 82 serious ADRs occurring in 44 (6.3%) patients (385 serious adverse events in 184 (26.2%) patients). Although 11 (1.6%) interstitial lung disease (ILD) cases were reported, all were observed in patients with disease that may contribute to ILD and therefore it is difficult to assess if ambrisentan was associated with these events. There was no difference in safety in relation to the presence/absence of connective tissue disease-related PAH (CTD-PAH) or combination therapy. Among 677 patients subjected to efficacy analysis, those in whom hemodynamic status was determined before and after treatment showed improvement in the mean pulmonary arterial pressure and pulmonary vascular resistance after treatment.

CONCLUSION

The interim results showed safety consistent with the known profile of ambrisentan in terms of the types and frequencies of ADRs in patients with PAH in real clinical practice, in comparison with previous clinical trials in Japan and the rest of the world. Thus, these results provided another corroboration of the tolerability of ambrisentan and we continue to monitor proper use information via the post-marketing surveillance to ensure any new safety signals are identified in a timely manner (ClinTrial.gov: NCT01406327).

Evaluation of efficacy, safety and tolerability of Ambrisentan in Chinese adults with pulmonary arterial hypertension: a prospective open label cohort study

Background

Although several new drugs have been approved in recent years, pulmonary arterial hypertension (PAH) remains a rapidly progressive disease with a poor prognosis. Ambrisentan, a selective endothelin type A antagonist, has been approved for treatment of PAH. This open label study assessed the efficacy and safety of ambrisentan in Chinese subjects with PAH.

Methods

Eligible patients with PAH (World Health Organisation [WHO] functional class [FC] II orIII) were enrolled and received Ambrisentan (5 mg) once daily for a 12-week preliminary evaluation period, and a 12-week dose-adjustment period (dose titration to 10 mgallowed). Endpoints included: change from baseline in 6-Minute Walk Distance (6-MWD), N-Terminal Pro B-Type Natriuretic Peptide (NT-pro-BNP), WHO FC, Borg Dyspnoea Index (BDI), clinical worsening of PAH and incidences of adverse events (AE).

Results

One hundred thirty-three subjects (85 % women, mean age: 36 years) with PAH (WHOFC II or III) were enrolled and received ambrisentan (5 mg) once daily for a 12-week preliminary evaluation period, and a 12-week dose-adjustment period. Mean (SD) duration of drug exposure was 161.7 (27.13) days. Ambrisentan (average daily dose of 6.27 mg) significantly improved exercise capacity (6MWD) from baseline (mean: 377.1 m [m]) at week 12 (+53.6 m, p < 0.001) (primary endpoint). Improvement in exercise capacity was noted as early as week 4, and was sustained up to week 24 (+ 64.4 m, p < 0.001). NT-pro-BNP plasma levels decreased significantly (p < 0.001) at week 12 (−861.4 ng/L) and week 24 (−806 ng/L) from baseline (mean: 1600.7 ng/L). The WHO FC showed improvements for 44 subjects at week 12 and 51 subjects at week 24. BDI scores decreased significantly at week 12 (−0.3, p < 0.001) and week 24 (−0.2, p = 0.003) from baseline (mean: 2.5). Four patients died during the study (sudden cardiac death [n = 2], cerebral haemorrhage [n = 1], cardiac failure [n = 1]). Drug related adverse events occurred in 34.3 % of subjects; peripheral oedema (11.2 %) and flushing (8.2 %) occurred most frequently.

Conclusion

Ambrisentan (5 and 10 mg, orally) significantly improved the exercise capacity in Chinese PAH subjects with a safety profile similar to that observed in global studies.

Trial registration

NCT No. (ClinicalTrials.gov): NCT01808313; Registration date (first time): February 28, 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0361-9) contains supplementary material, which is available to authorized users.

Use of outcome measures in pulmonary hypertension clinical trials

OBJECTIVES

To evaluate the use of surrogate measures in pulmonary hypertension (PH) clinical trials and how it relates to clinical practice.

BACKGROUND

Studies of pulmonary arterial hypertension (PAH) employ a variety of surrogate measures in addition to clinical events because of a small patient population, participant burden, and costs. The use of these measures in PH drug trials is poorly defined.

METHODS

We searched PubMed/MEDLINE/Embase for randomized or prospective cohort PAH clinical treatment trials from 1985 to 2013. Extracted data included intervention, trial duration, study design, patient characteristics, and primary and secondary outcome measures. To compare with clinical practice, we assessed the use of surrogate measures in a clinical sample of patients on PH medications at Duke University Medical Center between 2003 and 2014.

RESULTS

Between 1985 and 2013, 126 PAH trials were identified and analyzed. Surrogate measures served as primary endpoints in 119 trials (94.0%). Inclusion of invasive hemodynamics decreased over time (78.6%, 75.0%, 52.2%; P for trend = .02), while functional testing (7.1%, 60.0%, 81.5%; P for trend < .0001) and functional status or quality of life (0%, 47.6%, 62.8%; P for trend < .0001) increased in PAH trials over the same time periods. Echocardiography data were reported as a primary or secondary outcome in 32 trials (25.4%) with increased use from 1985-1994 to 1995-2004 (7.1% vs 35.0%, P = .04), but the trend did not continue to 2005-2013 (25.0%). In comparison, among 450 patients on PAH therapies at our institution between 2003 and 2013, clinical assessments regularly incorporated serial echocardiography and 6-minute walk distance tests (92% and 95% of patients, respectively) and repeat measurement of invasive hemodynamics (46% of patients).

CONCLUSIONS

The majority of PAH trials have utilized surrogate measures as primary endpoints. The use of these surrogate endpoints has evolved significantly over time with increasing use of patient-centered endpoints and decreasing or stable use of imaging and invasive measures. In contrast, imaging and invasive measures are commonly used in contemporary clinical practice. Further research is needed to validate and standardize currently used measures.

Ambrisentan for the treatment of adults with pulmonary arterial hypertension: a review

OBJECTIVE

To provide an overview of the drug profile of the orally active, selective endothelin A receptor antagonist ambrisentan, and its efficacy and safety in the treatment of patients with pulmonary arterial hypertension (PAH).

RESEARCH DESIGN AND METHODS

Medical literature on the use of ambrisentan in PAH was identified using MEDLINE and EMBASE. Additional references were identified from the reference lists of published articles and from the authors' own bibliographies.

RESULTS

Significant improvements in exercise capacity were observed with approved dosages of ambrisentan (5 or 10 mg once daily) in the AMB-220 dose-ranging study and the pivotal ARIES-1 and ARIES-2 trials, with sustained effects up to 2 years observed in ARIES-E. Improvements in cardiopulmonary hemodynamic variables were reported in AMB-220 and ARIES-E (subset analysis). Ambrisentan had little or no effect on hepatic transporters in in vitro studies and displayed a low risk of potential drug-drug interactions, including those with other PAH therapies. Results from the VOLT post-marketing program confirmed the safety profile of ambrisentan observed in the ARIES studies, including the low incidence of liver function test abnormalities. Peripheral edema and anemia were common side effects of endothelin receptor antagonist therapies, including ambrisentan. In the recently completed AMBITION study (ClinicalTrials.gov Identifier: NCT01178073), upfront initial combination therapy with ambrisentan and tadalafil significantly reduced the risk of clinical failure (primary endpoint) by 50% compared with the pooled monotherapy groups.

CONCLUSIONS

The long-term efficacy and safety profile of ambrisentan in patients with PAH is supported by data from a comprehensive clinical trial program and real-life, post-marketing observations.

An update on the use of ambrisentan in pulmonary arterial hypertension

The development of effective oral treatments that are capable of modulating the activity of endothelin receptor 1 (ET-1) represents a significant milestone in the field of pulmonary arterial hypertension (PAH). Randomized clinical trials confirm that endothelin receptor antagonist (ERA) treatments confer significant improvements on important clinical endpoints, such as exercise capacity, functional class, quality of life and pulmonary hemodynamics. Moreover, ERAs may prevent or delay clinical worsening and retard disease progression.

Ambrisentan is a propanoic acid-based ERA, showing preferential affinity for the type A ET-1 over the type B receptor. It provides another valuable, effective treatment option in PAH. Two large, randomized-placebo controlled trials demonstrated the efficacy of ambrisentan in PAH at improving exercise tolerance as measured by the 6 min walk distance. Additional secondary measures of improvement including time to clinical worsening, survival, functional class, quality of life and hemodynamic variables have been reported in clinical trials. A favorably low incidence of aminotransferase elevation indicating lower hepatic toxicity than other ERAs has been observed. Ambrisentan can be safely administered with warfarin or sildenafil without the need for dose adjustment of either therapy. A once daily oral medication with relatively few side effects is an attractive option, especially as the use of therapies in combination continues to increase. Long-term data and hemodynamic data confirm the benefits can be compared with other ERAs with fewer drug–drug interactions and a better liver safety profile.

Long-term safety and efficacy of ambrisentan in Japanese adults with pulmonary arterial hypertension

OBJECTIVE

To investigate the safety and efficacy of long-term administration of ambrisentan in Japanese adults with pulmonary arterial hypertension (PAH).

RESEARCH DESIGN AND METHODS

In this open-label extension of a preceding multicenter dose-escalation study, 21 Japanese patients with PAH received treatment with 5 or 10 mg of ambrisentan once daily and were comprehensively evaluated every 12 weeks. The primary endpoint was the safety of long-term ambrisentan administration, as defined by the incidence and severity of adverse events. The secondary (efficacy) endpoints were change in exercise capacity (as indicated by 6-minute walk distance), World Health Organization functional class, Borg dyspnea index, plasma brain natriuretic peptide level, cardiopulmonary hemodynamics, and time to clinical worsening of PAH.

CLINICAL TRIAL REGISTRATION

NCT00554619.

RESULTS

The mean total duration of treatment (i.e., including the preceding dose-escalation study) was approximately 139 weeks. There were fewer adverse events related to ambrisentan in this study than in the preceding study, and we identified no new safety signals that might preclude the long-term use of ambrisentan among Japanese adults with PAH. Improvements observed in efficacy endpoints in the preceding study were maintained in the present study.

LIMITATIONS

This study did not include a control group and lacked the statistical power to reach definite conclusions regarding the efficacy of ambrisentan.

CONCLUSION

Our results suggest that long-term administration of ambrisentan is well tolerated and efficacious for Japanese adults with PAH.