Study of GLPG1837 in Subjects With Cystic Fibrosis (S1251N Mutation)

Inclusion criteria

• Male or female subjects ≥ 18 years of age, with a confirmed diagnosis of cystic fibrosis
• Subjects with gating S1251N CFTR mutation on at least one allele in the CFTR gene
• Subjects currently receiving treatment with ivacaftor on a stable regimen or not on a treatment regimen with ivacaftor, for at least 2 weeks prior to screening
• Weight ≥ 40.0 kg
• Subjects on stable concomitant treatment regimen for at least 4 weeks prior to baseline (excluding ivacaftor)
• Pre- or post-bronchodilator FEV1 ≥ 40% of predicted normal
• Subject will have to use highly effective contraceptive methods

Exclusion criteria

• On an ivacaftor-containing treatment regimen and unable or unwilling to discontinue ivacaftor for the washout and treatment periods of the study
• Concomitant use of antifungal drugs within 4 weeks of baseline
• A history of a clinically meaningful unstable or uncontrolled chronic disease
• Liver cirrhosis and portal hypertension
• Any significant change in the medical regimen for pulmonary health within 4 weeks of baseline
• Unstable pulmonary status or respiratory tract infection or changes in therapy for pulmonary disease within 4 weeks of baseline
• Abnormal liver function
• Clinically significant abnormalities on ECG
• History of malignancy, solid organ/haematological transplantation
• Abnormal renal function
• Participation in another experimental therapy study within 30 days or 5 times half-life