A Long Term Study of Ambrisentan in Pulmonary Arterial Hypertension Subjects Having Completed AMB-320 (NCT00423748) or AMB-321 (NCT00423202)

AMB-320/321-E was designed to provide long-term, controlled monitoring of pulmonary arterial hypertension (PAH) patients treated with ambrisentan (AMB) in order to properly define the adverse event profile associated with this endothelin receptor antagonist (ERA), including the incidence and severity of elevated serum liver function tests (LFTs). In addition, this study continued the efficacy assessments of the previous studies, examined long-term AMB treatment success, and compared long-term survival of subjects treated with AMB to the NIH registry of patients with PAH.

AMB-320 (ARIES-1; NCT00423748) and AMB-321 (ARIES-2; NCT00423202) were 12-week, Phase 3, randomized, double-blind, placebo-controlled, multicenter, efficacy studies of AMB in subjects with PAH. The objectives of these studies were to determine the effect of three doses of AMB (2.5, 5.0, and 10.0 mg) on exercise capacity, as well as several clinical measures of PAH. The current study (NCT00578786) was unblinded (by design) prior to completion. The ARIES studies were identical except for the dose groups assessed and the geographic locations where the studies were conducted. Both studies evaluated placebo and 5.0-mg AMB dose groups; however, AMB-320 (NCT00423748) also examined an AMB dose of 10.0 mg, while AMB-321 (NCT00423202) included an AMB dose of 2.5 mg. AMB-320/321-E was an optional study for subjects who had participated in AMB-320 (NCT00423748) or AMB-321 (NCT00423202) that allowed continued long-term treatment with AMB.

Eligibility Criteria:
Inclusion Criteria:

1. Subject must have completed Week 12 of AMB-320 (NCT00423748) or AMB-321 (NCT00423202) or must have received placebo during AMB-320 (NCT00423748) or AMB-321 (NCT00423202) and met two or more early escape criteria;
2. Subject must be competent to understand the information given in the Institutional Review Board (IRB) or Independent Ethics Committee (IEC) approved informed consent form and must sign the form prior to the initiation of any study procedures.
3. Female subject of childbearing potential must agree to use two reliable methods of contraception until study completion and for at least four weeks following their final study visit. Reliable methods include: birth control pills/implants/injections, intrauterine devices (IUDs), spermicide, diaphragms, or condoms.

Exclusion Criteria:

* Subjects must have met the exclusion criteria of the AMB-320 (NCT00423748) and AMB-321 (NCT00423202)studies. In addition, a subject who meets any one of the following criteria is ineligible for participation in the study:

  1. Subject receiving bosentan, sildenafil, or iv inotropes at any time within four weeks prior to the AMB-320/321-E Screening/Randomization Visit;
  2. Subject receiving chronic prostanoid therapy (epoprostenol, treprostinil, iloprost, beraprost, or any other investigational prostacyclin derivative) within four weeks prior to the AMB-320/321-E Screening/RandomizationVisit;
  3. Female subject who is pregnant or breastfeeding;
  4. Subject with cardiovascular, liver, renal, hematologic, gastrointestinal, immunologic, endocrine, metabolic, or central nervous system disease that, in the opinion of the Investigator, may adversely affect the safety of the subject and/or efficacy of the study drug or severely limit the lifespan of the subject;
  5. Subject who has demonstrated noncompliance with previous medical regimens;
  6. Subject who has a recent history of abusing alcohol or illicit drugs;
  7. Subject who has participated in a clinical study involving another investigational drug or device at any time within four weeks prior to the AMB-320/321-E Screening/Randomization Visit.