Clinical Trial Finder

Inclusion Criteria:

• - Able to provide informed consent.

• - Age ≥ 18 at the time of screening.

• - Diagnosis of cystic fibrosis (CF) - Regularly using elexacaftor/tezacaftor/ivacaftor (E/T/I) for ≥ 90 days.

• - FEV1 between 30% and 70%, inclusive, at time of screening.

• - Denies active smoking or vaping.

• - Clinically stable with no significant changes in health status within the 28 days prior to and including the screening visit.

• - Patients on cycled inhaled antibiotics will need to be either on or off their antibiotic for 7 days prior to Visit 1 and not scheduled to cycle during the 2-week treatment period until after Visit 2.

• - Has no other conditions that, in the opinion of the Site Investigator/Designee, would preclude informed consent, make study participation unsafe, complicate interpretation of study outcome data, or otherwise interfere with achieving the study objectives.

Exclusion Criteria:

• - Use of an investigational drug within 28 days prior to and including the screening visit.

• - Unable or unwilling to withhold hypertonic saline (HS) for 4 weeks (2 weeks prior to Visit 1 and 2 weeks between Visit 1 and Visit 2) - Unable or willing to withhold dornase alfa and bronchodilators on the morning of Visit 1 and Visit 2, until completion of study procedures.

• - Initiation of new chronic CF pulmonary therapy (e.g. dornase alfa, azithromycin, inhaled antibiotic) within 28 days prior to and including the screening visit.

• - No acute use of antibiotics (oral, inhaled, or intravenous) or acute use of systemic corticosteroids for respiratory tract symptoms within 28 days prior to and including the screening visit.

• - No chronic use of oral corticosteroids > 10 mg of prednisone or equivalent daily.

• - Unable to tolerate albuterol or other bronchodilator.

• - History of intolerance to HS or inhaled mannitol.

• - Pregnancy or breast feeding.

- Have had more than 2 chest computed tomography (CT) in the past year or a combination of procedures that are believed to have exposed the subject's lungs to >150 millisievert (mSv) - History of significant hemoptysis (>60 mL) in the last three months

Arms

Experimental: Inhaled Mannitol

All study participants will receive the same study treatment. Study treatment will be dry powder mannitol 400 mg twice a day by oral inhalation (the contents of 10 capsules administered individually) for 14 days +/- 2 days.

Interventions

Drug: - Mannitol Inhalant Product

A sugar alcohol indicated as an add-on maintenance therapy to improve pulmonary function in adult patients 18 years of age and older with cystic fibrosis.