Long-term Ambrisentan Extension Study for Pediatric Patients Who Participated in AMB112529

Phase 2

Completed

Conditions: Hypertension, Pulmonary

Interventions: Drug: Ambrisentan

Registration Number: NCT01342952

Lead Sponsor: GlaxoSmithKline

Brief Summary: An open label, long term extension to Study AMB112529. All subjects may remain in the extension study for a minimum of six months. Beyond the six month period, subjects may continue in the extension study until one of the following conditions is met:

the subject turns 18 years of age (when the subject can receive marketed product) the product is approved and available for use in the subject's age group, development for use in the paediatric population is discontinued. the subject decides he/she no longer wants to participate in the study, the investigator considers it is in the best interest of the subject to discontinue ambrisentan (e.g. for safety reasons).

The primary objective is the long-term safety and tolerability of ambrisentan in the paediatric PAH population. Secondary objectives are all cause mortality and change from baseline in Study AMB112529 on efficacy parameters.

Detailed Description: Pulmonary arterial hypertension (PAH) is a rare, progressive, highly debilitating disease characterized by vascular obstruction and the variable presence of vasoconstriction, leading to increased pulmonary vascular resistance and right-sided heart failure. If left untreated, PAH ultimately leads to right ventricular failure and death; adult subjects have a median survival of 2.8 years without treatment. Epidemiological estimates vary but prevalence in Europe is thought to be of the order of 15 cases per million. Large scale epidemiology studies of PAH in children have not been conducted and there is no or limited outcome data in paediatric PAH patients. A register in France (1995-1996) estimates the prevalence in children is as low as 3.7 cases per million. In a national, comprehensive country wide survey of the epidemiology of idiopathic PAH (IPAH) management and survival in the United Kingdom (UK) the incidence was 0.48 cases per million children per year and the prevalence was 2.1 cases per million children.

Ambrisentan (VOLIBRIS™ tablets) is an endothelin receptor antagonist (ERA) marketed in the European Union (EU) and some other countries by GlaxoSmithKline (GSK) and in the United States as LETAIRIS® by Gilead Sciences Inc. Ambrisentan is indicated for the treatment of adult patients with PAH to improve exercise capacity, decrease the symptoms of PAH, and delay clinical worsening.

The primary purpose of this long term paediatric study is to provide clinically relevant information on the long term safety of ambrisentan in children with the most common causes of PAH in this age group. This study is only open to patients who have participated in Study AMB112529, A randomized, open label study comparing safety and efficacy parameters for a high and a low dose of ambrisentan (adjusted for body weight) for the treatment of pulmonary arterial hypertension in paediatric patients aged 8 years up to 18 years, and in whom continued treatment with ambrisentan is warranted.

This study is part of a Paediatric Investigational Plan (PIP; EMEA-000434-PIP01-08) agreed with the European Medicines Agency's Paediatric Committee (PDCO).

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 38

Inclusion Criteria

Have participated in and complied, to the best of their ability, with the protocol for AMB112529 and have met one of the following:
1. Completed the Week 24 visit in AMB112529;
2. Required additional targeted treatment for PAH due to inadequate response to the current treatment or worsening of their clinical condition prior to week 24 in AMB112529;
3. Required reduction in dose of baseline targeted treatment for PAH after ambrisentan was added to the treatment regimen;
4. In the opinion of the investigator, continued treatment with ambrisentan is warranted.
A female is eligible to participate in this study, as assessed by the investigator, if she is of:
1. Non-childbearing potential (i.e., physiologically incapable of becoming pregnant); or,
2. Child-bearing potential - has a negative pregnancy test and is not lactating and, if sexually active, agrees to continue to use 2 reliable methods of contraception until study completion and for at least 30 days following the last dose of study drug (reliable methods of contraception are listed in Appendix 2).
Subject or subject's legal guardian is able and willing to give written informed consent. As part of the consent, female subjects of childbearing potential will be informed of the risk of teratogenicity and will need to be counselled in a developmentally appropriate manner on the importance of pregnancy prevention; and male subjects will need to be informed of potential risk of testicular tubular atrophy and aspermia.

Exclusion Criteria

Subjects who were withdrawn from ambrisentan in Study AMB112529;
Subjects who did not comply with the protocol in Study AMB112529;
Female subjects who are pregnant or breastfeeding;
Subjects with severe renal impairment (estimated creatinine clearance <30 mL/min assessed within the previous 45 days) at the point of transition from Study AMB112529 into this study;
Subject with clinically significant fluid retention in the opinion of the investigator;
Subject with clinically significant anaemia in the opinion of the investigator;
Subjects who are to enter another clinical trial or be treated with another investigational product after exiting Study AMB112529.

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Ambrisentan	Ambrisentan	Open label, flexible dosing from 2.5 mg to 10 mg (not to exceed 0.25 mg/kg) per day

Primary Outcome Measures

Name	Time	Method
Change From Baseline in Hematology Parameters: Basophils, Eosinophils, Lymphocytes, Monocytes, Total Neutrophils, White Blood Cells (WBC), Platelet Count	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following hematology parameters: Basophils, eosinophils, lymphocytes, monocytes, total neutrophils, WBC, platelet count. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Percentage of Saturated Oxygen Level (Physical Examination Parameter)	Up to 10 years and 11 months	Physical examination included measurement of saturated oxygen. End of study visit data is presented.
Change From Baseline in Vital Signs Parameter: Heart Rate	Baseline (Day 1) and up to 10 years and 11 months	Heart rate was measured for the participants at indicated time points. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Vital Sign Parameter: Height	Baseline (Day 1) and up to 10 years and 11 months	Height was measured for the participants at indicated time points. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Number of Participants With Non-serious Treatment-emergent Adverse Events (Non-STEAEs) and Serious Treatment-emergent Adverse Events (STEAEs)	Up to 10 years and 11 months	AE was defined as any untoward medical occurrence in participant or clinical investigation participant,temporally associated with use of medicinal product, whether or not considered related to medicinal product.SAE was defined as any untoward medical occurrence that, at any dose: results in death,is life threatening, requires hospitalization or prolongation of existing hospitalization,results in disability or incapacity,or is congenital anomaly or birth defect, important medical events that may not immediately life threatening or result in death or hospitalization but may jeopardize participant or may require medical or surgical intervention as per medical or scientific judgement or associated with drug-induced liver injury.TEAE is any event that was not present prior to initiation of study treatment or any event already present that worsens in either intensity or frequency following exposure to study treatment. TEAEs which were not serious TEAEs were considered as non serious TEAEs.
Change From Baseline in Chemistry Parameters: Calcium, Chloride, Carbon Dioxide (CO2) Content, Glucose, Potassium, Magnesium, Sodium, Phosphorus Inorganic, Blood Urea Nitrogen (BUN)	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following clinical chemistry parameters: Calcium, chloride, CO2 content, glucose, potassium, magnesium, sodium, phosphorus inorganic, and BUN. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Hematology Parameter: Mean Corpuscle Hemoglobin	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following hematology parameter: Mean Corpuscle Hemoglobin. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Number of Participants With Abnormal Values for Physical Examination Parameter: Jugular Venous Pressure	Up to 10 years and 11 months	Physical examination included measurement of Jugular venous pressure. Jugular venous pressure was assessed as normal or abnormal. Data for abnormal (improved, worsened and unchanged) jugular venous pressure is presented. End of study visit data is presented.
Number of Participants With Abnormal Values for Physical Examination Parameters: Ascites	Up to 10 years and 11 months	Physical examination included measurement of ascites. Ascites were assessed as present or absent. Data for ascites present with improved, worsened and unchanged is presented. End of study visit data is presented.
Number of Participants With Abnormal Values for Physical Examination Parameter: Peripheral Edema	Up to 10 years and 11 months	Physical examination included measurement of peripheral edema. Peripheral edema were assessed as present or absent. Data for peripheral edema present with improved, worsened and unchanged is presented. End of study visit data is presented.
Number of Participants With Abnormal Values for Physical Examination Parameter: Liver Size	Up to 10 years and 11 months	Physical examination included measurement of liver size. Any abnormal enlargement or reduction in the size of the liver is reported. Liver size was assessed as normal or abnormal. Data for abnormal (improved, worsened and unchanged) liver size is presented. End of study visit data is presented.
Change From Baseline in Vital Sign Parameter: Body Surface Area	Baseline (Day 1) and up to 10 years and 11 months	Body surface area was measured for the participants at indicated time points. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Number of Participants With Abnormal Electrocardiogram (ECG) Findings	Up to 10 years and 11 months	12-lead ECG was measured in a semi-supine position using an automated ECG machine. Abnormal findings were categorized as clinically significant (CS) and not clinically significant (NCS). Data for any time till end of study were presented.
Change From Baseline in Plasma Endocrine Parameters - Female: Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) at End of Study	Baseline (Day 1) and up to 10 years and 11 months	FSH and LH level of participants were measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Inhibin B at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Inhibin B level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Liver Function Parameters: Alanine Amino Transferase (ALT), Aspartate Amino Transferase (AST), Gamma Glutamyl Transferase (GGT), Total Bilirubin	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following clinical chemistry parameters: ALT, AST, GGT, total bilirubin. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Chemistry Parameters: Creatinine, Uric Acid	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following clinical chemistry parameters: Creatinine, uric acid. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Hematology Parameters: Hemoglobin and Mean Corpuscle Hemoglobin Concentration (MCHC)	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following hematology parameters: Hemoglobin and MCHC. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Hematology Parameter: Mean Corpuscle Volume	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following hematology parameter: Mean Corpuscle Volume. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Vital Signs Parameter: Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP)	Baseline (Day 1) and up to 10 years and 11 months	SBP and DBP was measured for the participants at indicated time points. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Inhibin B at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Inhibin B level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Male: Inhibin B at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Inhibin B level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Chemistry Parameters: Alkaline Phosphatase (ALP), Creatine Kinase (CK), Lactate Dehydrogenase (LDH)	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following clinical chemistry parameters: ALP, CK, LDH. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Chemistry Parameters: Albumin, Total Protein	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following clinical chemistry parameters: Albumin, total protein. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Hematology Parameters: Hematocrit	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following hematology parameters: Hematocrit. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Hematology Parameters: Red Blood Cell Count, Reticulocytes	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected from participants for analysis of following hematology parameters: Red Blood Cell count, reticulocytes. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Vital Signs Parameter: Weight	Baseline (Day 1) and up to 10 years and 11 months	Weight was measured for the participants at indicated time points. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Vital Sign Parameter: Body Mass Index	Baseline (Day 1) and up to 10 years and 11 months	Body mass index was measured for the participants at indicated time points. Body mass index was calculated as weight in kilograms (kg) divided by the square of their height in meters (m\^2). Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Sex Hormone Binding Globulin at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Sex hormone binding globulin level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Estriol at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Estriol level of female participants will be measured. Only those parameters having status as overall will be presented. Baseline is the last value recorded prior to start of study treatment from AMB112529. Change from Baseline is calculated by subtracting the Baseline value from the end of study post-dose visit value. Data for this endpoint will be available for this endpoint by June 2023
Change From Baseline in Plasma Endocrine Parameters - Female: Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	FSH and LH level of participants were measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Female: Sex Hormone Binding Globulin at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Sex hormone binding globulin level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Female: Estriol at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Estriol level of female participants will be measured. Only those parameters having status as overall will be presented. Baseline is the last value recorded prior to start of study treatment from AMB112529.Change from Baseline is calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants. Data for this endpoint will be available for this endpoint by June 2023
Change From Baseline in Plasma Endocrine Parameters - Male: FSH and LH at End of Study	Baseline (Day 1) and up to 10 years and 11 months	FSH and LH level of participants were measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Male: Total Testosterone at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Total Testosterone level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Estrone at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Estrone level of female participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Estrone at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Estrone level of female participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Female: Estradiol at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Estradiol level of female participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Female: Estradiol at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Estradiol level of female participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Male: Sex Hormone Binding Globulin at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Sex hormone binding globulin level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Male: Sex Hormone Binding Globulin at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Sex hormone binding globulin level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Male: Inhibin B at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Inhibin B level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Change From Baseline in Plasma Endocrine Parameters - Male: FSH and LH at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	FSH and LH level of participants were measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline in Plasma Endocrine Parameters - Male: Total Testosterone at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Total Testosterone level of participants was measured. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants.
Change From Baseline of Pubertal Development in Male: Testicular Volume at End of Study	Baseline (Day 1) and up to 10 years and 11 months	Testicular volume was assessed by Prader's orchiodometer and the assessment was performed by a pediatric endocrinologist using the Tanner's criteria. Only those parameters having status - overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value. Data reported for left and right testicular volume.
Change From Baseline of Pubertal Development in Male: Testicular Volume at 20 Years of Age of Participants	Baseline (Day 1) and at 20 years of age of participants	Testicular volume was assessed by Prader's orchiodometer and the assessment was performed by a pediatric endocrinologist using the Tanner's criteria. Only those parameters having status as overall were presented. Baseline was the last value recorded prior to start of study treatment from AMB112529.Change from Baseline was calculated by subtracting the Baseline value from the specified time point value. Only participants with data at 20 year visit is presented. When participants reached pubertal maturity prior to being 20 years of age then these tests were not repeated at 20-years of age of participants. Data reported for left and right testicular volume.
Time to Change in Dose of Ambrisentan or Other Targeted PAH Therapeutic Agents (Prostanoids, Phosphodiesterase Type 5 [PDE-5] Inhibitors) Due to Tolerability Issues	Baseline (Day 1) and up to 10 years and 11 months	Time to change in dose of ambrisentan or other targeted PAH therapeutic agents (prostanoids, Phosphodiesterase type 5 \[PDE-5\] inhibitors) due to tolerability issues was defined as the time from randomization to the first occurrence of a dose change due to tolerability issues.

Secondary Outcome Measures

Name	Time	Method
Number of Participants With All-cause Death	Up to 10 years and 11 months	Number of participants with all-cause death is presented.
Change From Baseline in Subject Global Assessment (SF-10) Health Survey for Children	Baseline (Day 1) and up to 10 years and 11 months	The short-form 10 (SF-10) Health Survey for children is a 10-item, 4-week recall, parent-completed health assessment that measures physical and psychosocial functioning for children ages five and over. Two summary scores were calculated: a Physical Summary Score (PHS) and a Psychosocial Summary Score (PSS) with a range of 5 to 30 points for each 5-item score. The aggregate score was then standardized and transformed to a norm-based scoring metric in accordance with the developer's guidelines. This generated the final standardized norm-based scores for PHS (range -10.90 to 57.21) and for PSS (range 8.81 to 62.28), respectively. A higher value on each summary score indicates better functioning. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Time to the Addition of Another Targeted PAH Therapeutic Agent Due to Lack of Beneficial Effect With Previous Therapy	Up to 10 years and 11 months	The time to addition of another targeted PAH therapeutic agents due to lack of beneficial effect with previous therapy was defined as the time from randomization to the first occurrence of lack of beneficial effect with previous therapy (not reaching set treatment goals).
Time to Change in Dose of Ambrisentan or Other Targeted PAH Therapeutic Agents (Prostanoids, PDE-5 Inhibitors) Due to Deterioration of Clinical Condition	Up to 10 years and 11 months	Time to change in dose of ambrisentan or other targeted PAH therapeutic agents (prostanoids, PDE-5 inhibitors) due to deterioration of clinical condition was defined as the time from randomization to the first occurrence of a dose change due to deterioration of clinical condition.
Change From Baseline in the 6 Minutes Walking Distance (6MWD) Test	Baseline (Day 1) and up to 10 years and 11 months	Participant's 6 MWD data has been presented into three categories as overall, with oxygen use and without oxygen use. The 6-minute walk test measures the distance that a participant can walk in 6 minutes. All participants were given standardized instructions and the distance walked was measured. Baseline which is the last value recorded prior to start of study treatment in AMB112529. Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Number of Participants With Change From Baseline in World Health Organization (WHO) Functional Class of PAH	Baseline (Day 1) and up to 10 years and 11 months	PAH was classified by WHO functional class (FC) at specific time points. There were four WHO FC grades based on severity of PAH symptoms (Class I=none, Class IV=most severe). Grades were mapped to numeric scale for which scores ranged from 1-4 (i.e. Class I=1 and IV=4). Change categorization was based on change from Baseline scores: -2, -1, 0, +1, +2. Data was categorized as No Change (0), Improved (-1,-2), Deteriorated (+1,+2). Baseline was the last value recorded prior to start of study treatment from AMB112529. Higher score indicated higher severity.Change from Baseline was calculated by subtracting the Baseline value from the end of study post-dose visit value.
Time to the First Clinical Worsening of PAH	Up to 10 years and 11 months	Time to clinical worsening of PAH is defined as the time from randomization to first occurrence of death (all cause), placed on active list for lung transplant, and/or atrial septostomy, hospitalization due to PAH deterioration, addition of another targeted PAH therapeutic agents (prostanoids, PDE-5 inhibitors) due to deterioration of clinical condition, change in dose of ambrisentan or other targeted PAH therapeutic agents (prostanoids, PDE-5 inhibitors) due to deterioration of clinical condition, PAH related deterioration identified by increase in WHO functional class, deterioration in exercise testing (i.e., 20% decrease in 6MWD on two consecutive tests -1 week apart, clinical signs or symptoms of right sided heart failure (i.e., new peripheral edema, increase in liver size, ascites, increase in jugular venous pressure, pericardial effusion, increased dyspnea).
Time to the Addition of Another Targeted PAH Therapeutic Agent Due to Deterioration of Clinical Condition	Up to 10 years and 11 months	Time to addition of another targeted PAH therapeutics agents due to deterioration of clinical condition was defined as the time from randomization to the first occurrence of deterioration of clinical condition.
Percentage Change From Baseline in Plasma N-terminal Pro-B-type Natriuretic Peptide (NT-Pro BNP) Concentration	Baseline (Day 1) and up to 10 years and 11 months	Blood samples were collected to analyze NT-Pro BNP concentration at specific time points. Baseline was the last value recorded prior to start of study treatment from AMB112529. Change from Baseline was calculated by subtracting Baseline value from the specified time point value.