Phase 1b/2, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Dose-Ranging Study Assessing the Safety, Pharmacokinetics, Pharmacodynamics, and Efficacy of HS235 Added to Background Treatment in Adults With PAH

Inclusion Criteria: Participants are eligible to be included in the study only if they meet all of the following criteria: 1. Male and female participants, 18 years of age and older. 2. Body Mass Index (BMI) 18.5 and 40 kg/m2 and body weight at or below 120 kg. 3. Baseline RHC performed during the Screening Period documenting: 1. A minimum PVR of ≥ 5 Wood units (WU) or ≥ 400 dyn·sec·cm-5 and, 2. A pulmonary artery wedge pressure (PAWP) of ≤ 15 mm Hg. 4. Diagnosis of WHO pulmonary arterial hypertension (PAH) Group 1. 5. Symptomatic PAH classified as WHO Functional class II to IV. 6. On…