A Phase 2, Open-label, Dose-escalation Study to Evaluate the Safety and Efficacy of RT234 on Exercise Parameters Assessed by Cardiopulmonary Exercise Testing (CPET) in Subjects with Pulmonary Arterial Hypertension (PAH)

This is a research study involving an investigational drug called RT234 (also called the study drug). The study drug is being developed to treat pulmonary arterial hypertension (PAH). The purpose of this study is to collect more information about the ability of RT234 to improve exercise capacity and safety of RT234 for the treatment of pulmonary arterial hypertension.