A Study of Ubenimex in Patients With Pulmonary Arterial Hypertension (WHO Group 1)

Inclusion Criteria

• Male or female, 18-75 years old.
• Has a diagnosis of WHO Group 1 PAH.
• Right heart catheterization performed at Screening with results that are:
• Mean pulmonary arterial pressure ≥25 mmHg (at rest) and
• Pulmonary venous hypertension (measured as pulmonary capillary wedge pressure (PCWP) ≤15 mmHg. If PCWP is not available, then mean left atrial pressure or left ventricular end-diastolic pressure ≤15 mmHg in the absence of left atrial obstruction. and
• Pulmonary vascular resistance (PVR) ≥300 dyn•s/cm5 (3.75 Wood units)
• Has WHO/NYHA-FC of II or III.
• Be on stable dose of at least one of the following PAH-specific therapies: endothelin receptor antagonist, an agent acting on the nitric oxide pathway (phosphodiesterase type 5 inhibitor or soluble guanylate cyclase stimulator), and/or a prostacyclin or prostacyclin analog.
• Has a 6-minute walk distance that is ≥150 and ≤500 meters.
• Have a ventilation-perfusion scan that rules out thromboembolic disease.

Exclusion Criteria

Exclusions Related to Cardiovascular Disease

• History of uncontrolled hypertension
• Persistent hypotension at Screening.
• Evidence or history of left-sided heart disease and/or clinically significant cardiac disease in which pulmonary hypertension is more likely WHO Group 2.
• Acute decompensated heart failure within 1 month of Screening.
• Recent initiation ( 3 × upper limit of normal (ULN) and/or bilirubin level >2 × ULN.
• Absolute neutrophil count <1500 mm3.
• Hemoglobin concentration <9 g/dL at Screening.
• Hepatic dysfunction as defined by Child-Pugh Class B or C