This study was an open-label extension study to determine the long-term safety and tolerability of ralinepag in subjects with World Health Organization (WHO) Group 1 pulmonary arterial hypertension (PAH) who have completed Study APD811-003, or who were assigned to receive placebo and were discontinued due to clinical worsening.

This study was an open-label extension study to determine the long-term safety and tolerability of ralinepag in subjects with WHO Group 1 PAH who completed Study APD811-003. Subjects who completed Study APD811-003 and met eligibility criteria for Study APD811-007 were enrolled. Additionally, placebo-treated subjects who discontinued study drug treatment due to clinical worsening in Study APD811-003 were permitted to enroll in Study APD811-007, upon approval of the medical monitor, provided that all end of study procedures including right heart catheterization (RHC) were performed per the study protocol. The Week 25 Visit in Study APD811-003 served as the Baseline Visit for Study APD811-007.

All subjects enrolled in Study APD811-007 received open-label treatment with ralinepag. The starting dose and titration schedule were individually determined and in accordance with the starting dose and titration schedule optimized from Study APD811-003. Adjustments in the dose and titration schedule were made according to subject tolerability.

After an individual subject completed Study APD811-003 and that subject's database was locked, subject unblinding occurred. Subjects on active treatment (ralinepag) remained on their current dose and had onsite clinical assessments performed every 3 months until the subject was discontinued from the study.

Subjects in the placebo treatment group underwent a dose titration period until a stable, maximum tolerated dose (MTD) was reached (up to 9 weeks), followed by a treatment period after the MTD was determined during which monthly onsite clinic assessments were performed for the first 3 months and then every 3 months until the subject was discontinued from the study or the study was terminated. Dose reductions could be made at any time for safety reasons. Incremental dose increases were also allowed during the Treatment Period at the discretion of the Investigator (as clinically indicated) and according to the stepwise titration scheme.

Subjects were assessed for clinical worsening during each clinic visit. If clinical worsening was confirmed, the Investigator could have opted to either continue treatment with ralinepag at the current dose, increase the dose of ralinepag, interrupt treatment, or discontinue the subject at his/her discretion.

In addition, attempts were made to contact all subjects at the time of Study APD811-007 termination to assess their vital (mortality) status. After the last subject enrolled in Study APD811-007 completed approximately 6 months of the study, a cumulative all-subject data analysis was performed for all subjects who entered the study. Subjects continued to have visits to the clinic every 3 months until the Sponsor discontinued the study. At the time of the Sponsor's decision to discontinue the study, all ongoing subjects completed an End of Study Visit. A 28-day Follow-up Visit was conducted to ensure appropriate subject safety. Subjects who remained on ralinepag were eligible to transition into the Phase 3 open-label extension study (ROR-PH-303) prior to APD811-007 study termination. For those subjects that did not enroll in Study ROR-PH-303, a 28-day Follow-up Visit was conducted to evaluate ongoing subject safety, including survival status.

Inclusion Criteria:

• Evidence of a personally signed and dated informed consent document.
• Was willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures and was deemed an appropriate candidate for participation in a long-term extension study.
• Female subjects were nonpregnant, nonlactating, surgically sterile or postmenopausal, or agreed to use an accepted method of birth control for at least 3 months prior to the first dose, during, and for at least 30 days after the last dose of study drug.
• Male subjects were either surgically sterile or agreed to use a condom with spermicide when sexually active with a female partner who was not using an acceptable method of birth control during the study and for 30 days after the last dose of study drug.
• Male and female subjects agreed not to participate in a conception process during the study and for 30 days after the last dose of study drug.
• Fulfilled all eligibility criteria for Study APD811-003 and completed the study as planned.

Subjects who were assigned to placebo in Study APD811-003 and experienced clinical worsening in that study could enroll in Study APD811-007 after completing all end of study procedures per protocol, including RHC, for Study APD811-003 and had their data locked.

Exclusion Criteria:

• Subjects who enrolled in Study APD811-003 and were withdrawn from study drug treatment due to any adverse event (AE), serious adverse event (SAE), or subjects who did not complete Study APD811003, with the exception made for placebo-treated subjects who experienced a clinical worsening event.
• Female •subjects who wished to become pregnant.
• Systolic blood pressure <90 mmHg at Baseline.
• Other severe acute or chronic medical or laboratory abnormalities that could have increased the risk associated with study participation or investigational product administration or interfered with the interpretation of study results and, in the judgment of the investigator, would have made the subject inappropriate for entry into this study.