Key Inclusion Criteria:

- Able to understand and complete study requirements and provide written informed consent.

- Males and females ≥ 18 and ≤ 80 years of age at the time of informed consent. All sexually active male subjects and female subjects of childbearing potential must use
an acceptable, highly effective method of contraception.

- Diagnosed with PAH belonging to Group 1 pulmonary hypertension (PH) per European Society of Cardiology/ European Respiratory Society Guidelines for the diagnosis and treatment of PH

- Documentation of having PAH as confirmed by right heart catheterization (RHC) within 12 months prior to screening and meeting the following criteria:

- New York Heart Association functional class II, III, or IV at the screening visit.

- Documented stable doses

- Can complete a screening 6MWD of ≥150 meters

- Forced expiratory volume in 1 second (FEV1) >65% of predicted and FEV1/forced vital capacity (FVC) ratio > 65% at screening.

Key Exclusion Criteria:

- Pregnant or lactating female at screening or baseline.

- Left ventricular ejection fraction of ≤ 45% on a historical echocardiogram within 6 months of screening. Patients who recovered their LVEF culd be allowed, as judged by
investigator.

- History of sleep apnea, parenchymal lung disease, or left-sided heart disease (including but not limited to aortic or mitral valve disease, pericardial constriction, restrictive or congestive cardiomyopathy, or coronary artery disease)
per investigator's discretion.

- Experienced an acute exacerbation of disease or hospitalization for any reason within 30 days of signing the ICF or prior to baseline.

- Use of any investigational drug/device or participation in any other investigational study with therapeutic intent within 30 days or 5 half-lives, whichever is longer, prior to signing the ICF.

- Systolic blood pressure < 90 mmHg or ≥ 160 mmHg at baseline.

- Screening electrocardiogram (ECG) with QTcF > 450 ms for male subjects or > 480 ms for female subjects.

- Musculoskeletal disorder (e.g., arthritis affecting the lower limbs, recent hip or knee joint replacement) or any disease that would likely be the primary limit to ambulation or subject is connected to a machine that is not portable enough to allow for a 6-minute walk test (6MWT).

- Alanine aminotransferase or aspartate aminotransferase levels > 3 × upper limit of normal reference range, clinically significant liver disease/dysfunction, or known Child-Pugh Class C hepatic disease.

- Estimated glomerular filtration rate < 30 mL/min/1.73 m^2 or requires dialysis.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 11/27/23.  Questions regarding updates should be directed to the study team contact.