This study tests a medicine called seralutinib to see if it is safe and works well over a long time. Seralutinib is a medicine that you breathe in, and it's for people with a lung condition called PAH (Pulmonary Arterial Hypertension). PAH is when the blood pressure in your lungs is too high, making it hard for your heart to pump blood through your lungs.

The study is open-label, meaning both you and your doctor know you are getting the medicine. You can join if you finished a previous seralutinib study and agree to follow the study rules. You will keep using the medicine until it is officially sold in stores or until the study stops.

Key Points:

• Continue treatment until market approval or study ends.
• Must have completed a prior seralutinib study.
• Participants must use birth control if they can have children.