Pre-screening

• You will be required to stay on your current pulmonary arterial hypertension medications at the same dose for 12 weeks prior to screening

Confirming your eligibility to take part in the study

• Screening period of up to 4 weeks
• Full medical check-up, including discussing medical history
• Blood and urine sample tests
• Tests and checks on your heart and lungs (e.g., echo and electrocardiogram, 6MWT, and lung function test)
• Right heart catheterization will be required at screening, unless you have had one within the last 6 months

Study period

• You will be randomized after screening to receive seralutinib or placebo capsules twice a day, inhaled with a dry powder inhaler
• You will be required to attend check-up appointments to monitor your disease and assess the safety of the study drug throughout the study
• Neither you nor the study doctor will know which study drug you will be taking
• The study will last up to 48 weeks, or until the last patient in the PROSERA Study has completed 24 weeks of treatment

After the final dose

• If you decide not to take part in the PROSERA-EXT Study (open-label extension), 4 weeks after your last dose, you will attend a follow-up appointment
• The follow-up allows the study doctor to monitor your health after you have stopped receiving treatment
• Tests may include full medical check-up and blood and urine sample tests

Open-Label Extension Study

• Once you complete the main study, you will have the opportunity to join an open-label extension (OLE) study, called PROSERA-EXT
• You will have the chance to continue taking seralutinib, or switch to seralutinib if you were taking placebo