Conflict of interest: M. Humbert reports grants from Gossamer and Merck, consultancy fees from 35 Pharma, Aerovate, AOP Orphan, Chiesi, Ferrer, Gossamer, Janssen, Keros, Liquidia, Merck, Novartis, Respira, Roivant and United Therapeutics, payment or honoraria for lectures, presentations, manuscript writing or educational events from Janssen and Merck, and participation on a data safety monitoring board or advisory board for 35 Pharma, Aerovate, Janssen, Keros, Merck, Novartis and United Therapeutics. G. Kovacs reports funding for the PEX-NET Clinical Research Collaboration from the European Respiratory Society, grants from Janssen and Boehringer Ingelheim, consultancy fees from MSD, Boehringer Ingelheim, AOP Orphan, Chiesi, Ferrer, Bayer, Janssen, GSK, Liquidia and AstraZeneca, payment or honoraria for lectures, presentations, manuscript writing or educational events from MSD, Boehringer Ingelheim, AOP Orphan, Chiesi, Ferrer, Bayer, Janssen, GSK, Liquidia and AstraZeneca, support for attending meetings from MSD, Janssen, Boehringer Ingelheim and AOP Orphan, and participation on a data safety monitoring board or advisory board for MSD, Boehringer Ingelheim, Ferrer and Liquidia.