This clinical trial is focused on studying the long-term safety and effectiveness of a treatment for Pulmonary Arterial Hypertension (PAH). PAH is a condition where the blood pressure in the arteries of the lungs is higher than normal, which can lead to heart problems. The treatment being tested is called seralutinib, which is taken as an inhalation powder in a hard capsule form. This means the medication is inhaled directly into the lungs to help manage the condition.

The purpose of the study is to evaluate how safe and tolerable seralutinib is for people with PAH over a long period. Participants in the study will continue using the medication and will be monitored for any side effects or changes in their condition. The study will also look at how the treatment affects the distance participants can walk in six minutes, which is a common way to measure physical ability in people with PAH.

Participants will be involved in the study for up to 52 weeks, during which they will have regular check-ups and tests to ensure their safety and to gather information about the treatment’s effects. The study will help researchers understand more about the long-term use of seralutinib and its potential benefits for people living with Pulmonary Arterial Hypertension.