For participants and families

PAH narrows and stiffens the small arteries in the lungs, so the right side of the heart has to work harder to push blood through them. It affects roughly 15 to 50 people in every million.

Tiprelestat is a lab-made copy of elafin, a protein your body already produces. It blocks an enzyme called neutrophil elastase, which appears to drive the scarring and inflammation in PAH. It is investigational: it has not been approved by the FDA.