This is a non-randomized, open-label extension study of LTP001 for participants with PAH who complete the parent study CLTP001A12201. Eligible participants will be presented with the opportunity to enroll in the extension study at the end of treatment visit of the parent study. Participants in the extension study will receive a once daily dose of LTP001 for 52 weeks regardless of their parent study treatment (i.e. LTP001 or placebo). Visits to assess the safety, tolerability and efficacy of LTP001 will take place at Weeks 5, 13, 26, 39 and 52, including a right heart catheterization at Week 26 and a 6-minute walk test and echocardiography at Weeks 26 and 52. Participants will have safety follow-up phone calls at week 9 and 17, and may be invited for unscheduled assessments at the site if deemed necessary. At Week 56, approximately 30 days after the treatment period, participants will have one safety follow-up phone call. The safety and efficacy profile of LTP001 observed in this extension study as well as the parent study will determine the continuation of the extension study
