A Study Evaluating the Efficacy and Safety of Ralinepag to Improve Treatment Outcomes in PAH Patients

Open to people ages 18-75

1. At least 18 years of age.
2. Evidence of a personally signed and dated informed consent form indicating that the subject has been informed of all pertinent aspects of the study prior to initiation of any study-related procedures.
3. Subjects who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures
4. Primary diagnosis of symptomatic PAH
5. Has had a right heart catheterization (RHC) performed at or within 3 years of Screening (RHC will be performed during Screening if not available) that is consistent with the diagnosis of PAH
6. Has WHO/ NYHA functional class II to IV symptoms.
7. If on PAH-specific background oral therapy, subject is on stable therapy with either an endothelin receptor antagonist (ERA) and/or a phosphodiesterase type 5 inhibitor (PDE5-I) or a soluble guanylate cyclase (sGC) stimulator. Subjects may be naïve to PAH-specific treatment.
8. Has a 6MWD of ≥150 meters.

1. For subjects with known HIV-associated PAH, a cluster designation 4 (CD4+) T-cell count <200/mm3 within 90 days of Baseline.
2. Must not have 3 or more left ventricular dysfunction risk factors as defined in the study protocol.
3. Has evidence of more than mild lung disease on PFTs performed within 180 days prior to, or during Screening.
4. Has evidence of thromboembolic disease as determined by a V/Q lung scan or local standard of care diagnostic evaluation at or after diagnosis of PAH.
5. Current diagnosis of uncontrolled sleep apnea as defined by the Investigator.
6. Male subjects with a corrected QT interval using Fridericia's formula (QTcF) >450 msec and female subjects with a QTcF >470 msec on ECG measured at Screening or Baseline in subjects without evidence of intraventricular conduction delay (IVCD). In the presence of IVCD, subjects will be excluded if the QTcF >500 msec for both males and females.
7. Severe chronic liver disease (ie, Child-Pugh C), portal hypertension, cirrhosis or complications of cirrhosis/portal hypertension (eg, history of variceal hemorrhage, encephalopathy).
8. Confirmed active infection with hepatitis B virus (HBV) or hepatitis C virus (HCV).
9. Subjects with alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥3 times the upper limit of normal (ULN) or total bilirubin ≥2 × ULN at Screening.
10. . Chronic renal insufficiency as defined by serum creatinine >2.5 mg/dL or requiring dialysis at Screening.
11. . Hemoglobin concentration <9 g/dL at Screening.
12. . Subjects treated with an IV or SC prostacyclin pathway agent (eg, epoprostenol, treprostinil, or iloprost) at any time prior to Baseline (use in vasoreactive testing is permitted).
13. . Subjects treated with an inhaled or oral prostacyclin pathway agent (iloprost, treprostinil, beraprost, or selexipag) that was stopped for a safety or tolerability issue.
14. . Subject has pulmonary veno-occlusive disease.
15. . Malignancy diagnosed and/or treated within 5 years prior to Screening, with the exception of localized non-metastatic basal cell or squamous cell carcinoma of the skin or in-situ carcinoma of the cervix excised with curative intent.
16. . Subject tests positive for amphetamine, cocaine, methamphetamine, methylenedioxymethamphetamine or phencyclidine in urine drug screen performed at Screening, or has a recent history (6 months) of alcohol or drug abuse.