Study Name: Ralinepag 303

Study Objective: A Phase 3 open-label extension (OLE) study to evaluate the long-term safety and efficacy of ralinepag in subjects with World Health Organization (WHO) Group 1 pulmonary arterial hypertension (PAH) (ADVANCE Extension)

Key Inclusion Criteria:

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

Key Exclusion Criteria:

1. Subjects who withdrew consent during participation in another ralinepag study.
2.  Subjects who have undergone lung or heart/lung transplant or the initiation of long-term
3. Parenteral (IV or SC infusion) or inhaled therapy with a prostacyclin or oral
4. therapy with another IP receptor agonist during the time since participation in their

• original ralinepag study.

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