A Study of Sotatercept for the Treatment of Pulmonary Arterial Hypertension (PAH)

Inclusion Criteria

• Age ≥18 years
• Documented diagnostic right heart catheterization (RHC) at any time prior to Screening confirming diagnosis of WHO diagnostic pulmonary hypertension Group I: PAH in any of the following subtypes:

i. Idiopathic ii. Heritable PAH iii. Drug- or toxin-induced PAH iv. PAH associated with connective tissue disease v. PAH associated with simple, congenital systemic-to-pulmonary shunts at least 1 year following shunt repair

• Symptomatic pulmonary hypertension classified as WHO functional class II or III
• Screening RHC documenting a minimum PVR of ≥400 dyn·sec/cm5 (5 Wood units)
• Pulmonary function tests (PFTs) within 6 months prior to Screening as follows:
• Total lung capacity (TLC) >70% predicted; or if between 60 to 70% predicted, or not possible to be determined, confirmatory high-resolution computed tomography (CT) indicating no more than mild interstitial lung disease (ILD), per investigator interpretation, or
• Forced expiratory volume (first second) (FEV1)/ forced vital capacity (FVC) >70% predicted
• Ventilation-perfusion (VQ) scan (or, if unavailable a negative CT pulmonary angiogram [CTPA] result, or pulmonary angiography result), any time prior to Screening Visit or conducted during the Screening Period, with normal or low probability result),
• No contraindication per investigator for RHC during the study
• 6MWD ≥150 and ≤550 meters repeated twice at Screening and both values within 15% of each other, calculated from the highest value
• PAH therapy at stable (per investigator) dose levels of SOC therapies

Exclusion Criteria

• Stopped receiving any pulmonary hypertension chronic general supportive therapy (e.g, diuretics, oxygen, anticoagulants, digoxin) within 60 days prior to study visit Cycle 1 Day 1 (C1D1)
• Received intravenous inotropes (e.g., dobutamine, dopamine, norepinephrine, vasopressin) within 30 days prior to study visit C1D1
• History of atrial septostomy within 180 days prior to Screening
• History of more than mild obstructive sleep apnea that is untreated
• Known history of portal hypertension or chronic liver disease, including hepatitis B and/or hepatitis C (with evidence of recent infection and/or active virus replication), defined as mild to severe hepatic impairment (Child-Pugh Class A-C)
• History of human immunodeficiency virus infection-associated PAH
• Prior exposure to sotatercept (ACE-011) or luspatercept (ACE-536)
• Initiation of an exercise program for cardiopulmonary rehabilitation within 90 days prior to C1D1 or planned initiation during the study (participants who are stable in the maintenance phase of a program and who will continue for the duration of the study are eligible).
• Uncontrolled systemic hypertension as evidenced by sitting systolic blood pressure (BP) >160 mm Hg or sitting diastolic blood pressure >100 mm Hg during Screening Visit after a period of rest
• Systolic BP 480 msec during Screening Period or C1D1
• Personal or family history of long QTc syndrome or sudden cardiac death
• Cerebrovascular accident within 3 months of C1D1
• History of restrictive or congestive cardiomyopathy
• Left ventricular ejection fraction (LVEF) 15 mmHg as determined in the Screening Period RHC.
• Any current or prior history of symptomatic coronary disease (prior myocardial infarction, percutaneous coronary intervention, coronary artery bypass graft surgery, or cardiac anginal chest pain)
• Acutely decompensated heart failure within 30 days prior to study visit C1D1, as per investigator assessment
• Significant (≥2+ regurgitation) mitral regurgitation (MR) or aortic regurgitation (AR) valvular disease
• Any of the following clinical laboratory values during the Screening Period prior to C1D1:
• Baseline Hgb >16.0 g/dL
• Serum alanine aminotransferase or aspartate aminotransferase levels >3X upper limit of normal (ULN) or total bilirubin >1.5X ULN within 28 days of C1D1
• Estimated glomerular filtration rat