A Study of Sotatercept in Japanese Pulmonary Arterial Hypertension (PAH) Participants (MK-7962-020)

Inclusion Criteria

• Documented diagnostic right heart catheterization (RHC) at any time prior to screening confirming the diagnosis of World Health Organization (WHO) pulmonary arterial hypertension (PAH) Group 1 in any of the following subtypes:
• Idiopathic PAH
• Heritable PAH
• Drug/toxin-induced PAH
• PAH associated with connective tissue disease
• PAH associated with simple, congenital systemic-to-pulmonary shunts at least 1 year following repair
• PAH classified as WHO functional class (FC) I or symptomatic PAH classified as WHO FC II to IV
• On stable doses of background PAH therapy and diuretics (if applicable) for at least 90 days prior to screening

Exclusion Criteria

• Diagnosis of PH WHO Groups 2, 3, 4, or 5
• Diagnosis of the following PAH Group 1 subtypes:
• Human immunodeficiency virus (HIV)-associated PAH
• PAH associated with portal hypertension
• Schistosomiasis-associated PAH
• PAH with features of significant venous/capillary pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis (PVOD/PCH) involvement
• Is on the waiting list for lung transplant
• Pregnant or breastfeeding women
• History of full or partial pneumonectomy
• Pulmonary function test (PFT) values of forced vital capacity (FVC) < 60% predicted at the screening visit or within 6 months prior to the screening visit.
• Initiation of an exercise program for cardiopulmonary rehabilitation within 90 days prior to the screening visit or planned initiation during the study.
• 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.
• History of restrictive, constrictive, or congestive cardiomyopathy.
• History of atrial septostomy within 180 days prior to the screening visit.
• Personal or family history of long QT syndrome (LQTS) or sudden cardiac death.
• Left ventricular ejection fraction (LVEF) < 45% on historical Echocardiogram (ECHO) within 6 months prior to the screening visit.
• Any symptomatic coronary disease events within 6 months prior to the screening visit.
• Cerebrovascular accident within 3 months prior to the screening visit.
• Significant (≥ 2+ regurgitation) mitral regurgitation or aortic regurgitation valvular disease, mitral stenosis and more than mild aortic valve stenosis.
• Prior exposure to sotatercept or luspatercept or history of allergic or anaphylactic reaction or hypersensitivity to recombinant proteins or excipients in investigational product
• Received intravenous inotropes (e.g., dobutamine, dopamine, norepinephrine, vasopressin) within 30 days prior to the screening visit
• Currently enrolled in or have completed any other investigational product study within 30 days
• Weight at the screening is over 85 kg