Postapproval observational studies showed that ETI restores CFTR chloride channel function in the airways and intestine to a level of approximately 40%–50% of CFTR function in healthy people (17), improves viscoelastic properties and mucociliary clearance (18, 19), and reduces mucus plugging (20–22) and airway infection and inflammation (18, 23, 24) in adolescent and adult patients with established lung disease. Here, CFTR is linked to lung disorder.