A Study Evaluating the Long-Term Efficacy and Safety of Ralinepag in Subjects With PAH Via an Open-Label Extension

Inclusion Criteria:

1. Evidence of a personally signed and dated informed consent form indicating that thesubject has been informed of all pertinent aspects of the study prior to initiationof any study-related procedures.

2. Subjects who are willing and able to comply with scheduled visits, treatment plan,laboratory tests, and other study procedures.

3. Completed the protocol-defined Study Drug Termination Visit or End of Study Visitprocedures in the preceding ralinepag study.

4. Both male and female subjects agree to use a medically acceptable method ofcontraception throughout the entire study period from informed consent through the 30 day Follow-up Visit, if the possibility of conception exists. Eligible male andfemale subjects must also agree not to participate in a conception process (i.e.,actively attempt to become pregnant or to impregnate, sperm donation, in vitrofertilization) during the study and for 30 days after the last dose of ralinepag.

Exclusion Criteria:

1. Subjects who prematurely discontinued investigational medicinal product (IMP) due toa drug-related AE/SAE or tolerability issue in the preceding ralinepag study inwhich they were enrolled, or subjects who did not complete all protocol definedstudy procedures at a Study Drug Termination Visit or End of Study Visit in thepreceding ralinepag study.

2. Subjects who withdrew consent during participation in another ralinepag study.

3. Female subjects who wish to become pregnant or who have a positive pregnancy test onDay 1 (OLE Entry Visit), or are lactating or breastfeeding.

4. Subjects who have undergone lung or heart/lung transplant or the initiation oflong-term parenteral or inhaled therapy with a prostacyclin during the time sinceparticipation in their original ralinepag study.

5. Subjects who had an emergency unblinding procedure in a prior Phase 2 or 3 study.