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