Study of REGN13335 in Adult Participants With Pulmonary Arterial Hypertension (PAH)

Key Inclusion Criteria

• Documented clinical diagnosis of PAH (Group 1 PH according to the 7th World Symposium on Pulmonary Hypertension (WSPH))
• WHO functional class II or III (slight to marked limitation of functional status due to PAH)
• Receiving background Standard Of Care (SOC) therapy for PAH on a stable dose and regimen, as determined by the investigator, as described in the protocol
• PVR ≥400 dynes∙sec/cm\^5 (5 Wood units) based on Right Heart Catheterization (RHC) during the screening period
• Has 6MWD ≥150 and ≤550 meters repeated twice during screening as described in the protocol

Key Exclusion Criteria

• Has Group 2 (PH associated with left heart disease), Group 3 (PH associated with lung diseases and/or hypoxia), Group 4 (PH associated with pulmonary artery obstructions), or Group 5 (PH with unclear and/or multifactorial mechanisms) PH according to the 7th WSPH
• Pulmonary Arterial Wedge Pressure (PAWP) >15 mm Hg by RHC during the screening period
• History of left-sided heart disease and/or clinically significant cardiac disease, as described in the protocol
• Obstructive lung disease defined as Forced Expiratory Volume in 1 second (FEV1)/Forced Vital Capacity \<0.7 and FEV1 \<70% of the predicted value as described in the protocol
• Evidence of interstitial lung disease as defined in the protocol
• Evidence of chronic thromboembolic pulmonary disease or acute pulmonary embolism as described in the protocol
• Participants requiring anticoagulation and/or antiplatelet therapy for an underlying medical condition as described in the protocol
• Has any history of intracranial bleeding or any history of elevated intracranial pressure
• Has any history of bleeding meeting criteria as described in the protocol

Note: Other protocol-defined Inclusion/ Exclusion criteria apply