Study to Evaluate Efficacy and Safety of JTT-251 in Participants With Pulmonary Arterial Hypertension

A Phase 2, Multicenter, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy and Safety of JTT-251 Administered for 24 Weeks to Participants With Pulmonary Arterial Hypertension (RELIEF-PAH)

Study to evaluate the efficacy, safety, tolerability and pharmacokinetics of JTT-251 administered for 24 weeks in participants with pulmonary arterial hypertension (PAH)

This is a study to evaluate the efficacy, safety, tolerability and pharmacokinetics of JTT-251 administered for 24 weeks in participants with pulmonary arterial hypertension (PAH). Participants completing this study (RELIEF-PAH) will be eligible to enroll in an open-label extension study (RELIEF-PAH OLE) to evaluate the long-term efficacy, safety, tolerability and pharmacokinetics of JTT-251 in participants with PAH.

Inclusion Criteria:

• Diagnosis of PAH as classified by idiopathic, heritable, drug and toxin- induced, congenital heart disease or associated with connective tissue disease (i.e., WHO Group 1)
• Clinical diagnosis of PAH confirmed by RHC at any time prior to Visit 1
• WHO functional status of Class II-IV at Visit 1
• Two 6MWD test measurements between 100 and 450 meters with a relative difference of ≤15%. The baseline 6MWD test must be performed at Visit 2 before randomization.
• Have a qualifying RHC performed between Visit 1 and Visit 2
• On stable dose(s) of guideline-directed medical therapy for PAH (endothelin receptor antagonists, phosphodiesterase type-5 (PDE-5) inhibitors, soluble guanylate cyclase stimulators and prostacyclin pathway analogs) for at least 90 days prior to the qualifying RHC

Exclusion Criteria:

• PAH associated with portal hypertension, human immunodeficiency virus (HIV), schistosomiasis or sickle cell disease as well as participants with pulmonary parenchymal disease or thromboembolic disease
• Known significant left heart disease including: left ventricular dysfunction (i.e., left ventricular ejection fraction <35%); hemodynamically compromising, symptomatic, or severe aortic stenosis, aortic regurgitation, mitral stenosis, mitral regurgitation
• Pulmonary hypertension belonging to WHO groups 2 to 5
• Moderate to severe obstructive lung disease defined as forced expiratory volume in 1 second (FEV1) <55% of predicted value
• Moderate to severe restrictive lung disease defined as total lung capacity (TLC) <60% of predicted value
• Acute decompensated heart failure or hospital admission for worsening PAH symptoms within 30 days prior to the qualifying RHC