Study ROR-PH-303, ADVANCE EXTENSION, is an open-label extension (OLE) study for participants with WHO Group 1 PAH who have participated in another Phase 2 or Phase 3 study of ralinepag.

Study ROR-PH-303 is a multicenter, open-label extension (OLE) study for subjects with WHO Group 1 PAH who have participated in another Phase 2 or Phase 3 study of ralinepag and who qualify for entry based upon participation in the prior study. Subjects who discontinue participation in a prior study due to safety issues related to study medication or who fail to complete study procedures will not be eligible to enter Study ROR-PH-303. Subjects who meet all OLE entry criteria will be enrolled and will receive ralinepag in addition to their pre-existing PAH disease-specific background therapy.

For subjects who are enrolled from an ongoing double-blind Phase 2 or Phase 3 ralinepag study, a 16-week blinded Dose Titration Period will be completed following enrollment into the OLE. Subjects previously on ralinepag will continue on the same dose during the Dose Titration Period as received in the original study and will also initiate placebo treatment in the OLE.

Subjects who are enrolled from a non-blinded study or another OLE will not participate in the blinded Dose Titration Period in Study ROR-PH-303 but will be enrolled directly into the Treatment Period and continue on the dose of ralinepag received in the original study.

All subjects will receive ralinepag in the OLE study until premature discontinuation of ralinepag due to an AE/serious adverse event (SAE) or other reason, marketing approval of ralinepag is granted in the region in which the study is conducted, or the study is discontinued by the Sponsor.

Inclusion Criteria:

1. 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.
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 Visit procedures in the preceding ralinepag study.
4. Both male and female subjects agree to use a medically acceptable method of contraception throughout the entire study period from informed consent through the 30 day Follow-up Visit, if the possibility of conception exists. Eligible male and female subjects must also agree not to participate in a conception process (i.e., actively attempt to become pregnant or to impregnate, sperm donation, in vitro fertilization) 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 to a drug-related AE/SAE or tolerability issue in the preceding ralinepag study in which they were enrolled, or subjects who did not complete all protocol defined study procedures at a Study Drug Termination Visit or End of Study Visit in the preceding 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 on Day 1 (OLE Entry Visit), or are lactating or breastfeeding.
4. Subjects who have undergone lung or heart/lung transplant or the initiation of long-term parenteral or inhaled therapy with a prostacyclin during the time since participation in their original ralinepag study.
5. Subjects who had an emergency unblinding procedure in a prior Phase 2 or 3 study.