This clinical trial is focused on studying a condition known as Pulmonary Arterial Hypertension (PAH). PAH is a type of high blood pressure that affects the arteries in the lungs and the right side of the heart. The study is testing a treatment called AV-101 (imatinib), which is a medication that comes in capsule form and is inhaled using a special device. Imatinib is a type of medicine known as a tyrosine kinase inhibitor, which works by blocking certain proteins that can contribute to the disease.

The purpose of this study is to find the best dose of AV-101 for treating PAH and to evaluate its safety and effectiveness. Participants in the study will be randomly assigned to receive either AV-101 or a placebo. The study will last for 24 weeks, during which time participants will take the medication and have regular check-ups to monitor their health and the effects of the treatment. The study is divided into two parts: Phase 2b, which focuses on finding the optimal dose, and Phase 3, which confirms the effectiveness of the treatment.

Throughout the study, participants will undergo various assessments, including a test called right heart catheterization, which helps measure changes in the pressure in the lungs. Another important measure is the 6-minute walk distance (6MWD), which evaluates how far a person can walk in six minutes. These assessments will help determine how well the treatment is working and ensure it is safe for patients with PAH. The study aims to improve the quality of life for those affected by this condition by finding a more effective treatment option.