A Two-Part Study to Evaluate the Efficacy, Safety, Tolerability and Pharmacokinetics of Repeat Doses of Inhaled ETD001 in People With Cystic Fibrosis

Inclusion Criteria:

• Male & female ≥ 18 years of age, who fit one of the following criteria:

Women of childbearing potential using permitted contraception a minimum of 28 days before dosing until completion of the final follow up visit; Women of non-childbearing potential; Men using contraception from the time of the first dose, until completion of the final follow up visit;

• Confirmed diagnosis of CF

• FEV1 ≥ 40% and ≤ 90% of predicted normal for age, gender, and height

• Able to reproducibly perform spirometry manoeuvres

• Clinically stable CF lung disease

• Routine CF therapy has not changed within 28 days prior to screening.

• Provided written informed consent.

• Body mass index (BMI) > 16 and < 30 kg/m2

Exclusion Criteria:

• Abnormal liver function

• Abnormal renal function

• History of solid organ transplant

• Chest x-ray within the past 12 months with abnormalities suggesting unstablepulmonary disease other than CF

• Received CFTR modulator therapy in the 60 days before screening

• Changes in bronchodilator, corticosteroid or other anti-inflammatory medications 14days before screening

• Unable to withhold use of long-acting bronchodilators 24 hours or short-actingbronchodilators 6 hours before spirometry assessments

• Unable to withhold use of anti-cholinergics within 24 hours of spirometry

• Started dornase alfa, hypertonic saline, or other airway clearing therapy less than 28 days before screening

• Using inhaled antibiotics for less than 2 complete cycles and unable to complete theentire study during the off or on cycle.

• Changes in inhaled or oral antibiotic use within 14 days of screening

• Taking oral corticosteroids in excess of 10 mg/day or 20 mg every other day within 14 days of screening

• Use of diuretics, or renin-angiotensin aldosterone system antihypertensive drugs ,drospirenone, or trimethoprim in the 28 days before screening

• Presence of co-morbidities and medical history in the opinion of the investigator,may pose additional risk by participating in the study, or may confound the resultsof the study