Inhaled Mannitol on Mucociliary Clearance in Moderate to Severe Cystic Fibrosis

This study will provide important mechanistic information regarding the effect of inhaled mannitol (Bronchitol) in people with cystic fibrosis (PwCF) with moderate to severe disease who are already using elexacaftor/tezacaftor/ivacaftor (E/T/I). Many patients have already discontinued hypertonic saline and other pulmonary therapies because of the profound effect of E/T/I of their symptoms and lung function. Further, because both inhaled osmotic agents (i.e., Bronchitol, hypertonic saline \[HS\]) and E/T/I are believed to exert their beneficial effects through improvements in mucociliary clearance (MCC), it is unknown if the combination of these therapies might be additive or are redundant in a population with moderate to severe disease where bronchiectasis and chronic infection persists, and where eventual decline in lung function is expected over time. This study, therefore, will be the first to determine whether "add on" therapy with inhaled mannitol is able to further accelerate MCC in E/T/I patients. These data would provide some guidance regarding the use of these approved therapies in PwCF.