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

The study is a multicenter, open-label study for participants with WHO Group 1 PAH who have
participated in another Phase 2 or Phase 3 study of ralinepag and qualify for entry based
upon participation in the prior study. The study consists of 16-week blinded Dose Titration
Period during which subjects previously on ralinepag will receive the same dose as during the
previous study and subjects previously on placebo will undergo titration.

Inclusion Criteria:

- Evidence of a personally signed and dated informed consent document indicating that
the subject has been informed of all pertinent aspects of the study prior to
initiation of any study-related procedures.

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

- Completed the protocol-defined EOS procedures and EOS Visit in the original ralinepag
study.

- 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. Medically
acceptable methods of contraception include the following:

- oral, implantable, or injectable contraceptives (starting ≥60 days before dosing)
and diaphragm with vaginal spermicide, cervical cap with vaginal spermicide, or
male condom;

- male condom and partner using diaphragm with vaginal spermicide or cervical cap
with vaginal spermacide;

- standard intrauterine device (IUD; e.g., Copper T 380A IUD), intrauterine system
(IUS; e.g., LNg 20 IUS - progesterone IUD), progesterone implant, or tubal
sterilization (≥180 days after surgery);

- post vasectomy and male condom, partner using diaphragm with spermicide, cervical
cap with spermicide, estrogen and progesterone oral contraceptives ("the pill"),
estrogen and progesterone transdermal patch, vaginal ring, or progesterone
injection.

Exclusion Criteria:

- Subjects who prematurely discontinued IMP due to a drug-related AE/SAE or tolerability
issue in the original ralinepag study in which they were enrolled, or subjects who did
not complete all protocol defined study procedures at an EOS Visit (not Early
Termination Visit) in the original ralinepag study.

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

- Female subjects who wish to become pregnant or who have a positive pregnancy test on
Day 1 (OLE Entry Visit).

- Subjects who have undergone lung or heart/lung transplant or the initiation of
parenteral (i.v. infusion or subcutaneous injection) therapy with a prostacyclin
during the time since participation in their original ralinepag study.

- Subjects who had an emergency unblinding procedure in a prior Phase 2 or 3 study or
subjects who developed withdrawal criteria in their original study but were not
withdrawn.

- Any reason that, in the opinion of the investigator or medical monitor, precludes the
subject from participating in the study, e.g., non-compliance concerns, any previous
or intercurrent medical condition that may increase the risk associated with study
participation or that would confound study analysis or impair study participation or
cooperation.