This is a 20-week, Phase 1, single-center, open-label, dose-escalation study evaluating the safety and tolerability of daily oral artesunate in patients with PAH.

Inclusion Criteria

• Each participant must meet the following criteria to be enrolled in this study:
• Adults aged 18 to 75 years.
• WHO functional class I, II/III despite treatment with maximally tolerated doses of 2 or more treatment modalities including PDE5 inhibitors, guanylate cyclase stimulators, endothelin receptor antagonists, and prostanoids when appropriate.

Exclusion Criteria

• Participants who meet any of the following criteria will be excluded from the study.
• Participants with serious concomitant morbidity per investigator assessment.