Impact of CFTR modulator therapy on the use of maintenance treatment in patients with cystic fibrosis: a prospective dual-center study

Cystic Fibrosis Transmembrane Conductance Regulator modulators (CFTRm) have improved clinical outcomes in people with cystic fibrosis (pwCF), prompting reconsideration of the need for traditional maintenance therapies. Reliable data on the safety and clinical impact of reducing or discontinuing these treatments remain limited. We conducted a 12-month, prospective, observational study of 138 pwCF aged 2–56 years treated with CFTRm in two cystic fibrosis (CF) centers in Poland. Patients were stratified by age, baseline lung function, and maintenance therapy continuation. Outcomes included spirometry, body mass index (BMI), oscillometry, and clinical scores, compared between those who discontinued or continued maintenance treatments. A total of 61 of 138 patients (44%) discontinued at least one therapy. Discontinuation was more frequent for inhaled than oral therapies and occurred more often in adults with preserved pulmonary function. For most patients, discontinuing maintenance treatment did not worsen respiratory parameters or nutritional status, except for adults discontinuing short-acting bronchodilators, in whom small airway function deteriorated- X10 -0.26, AX + 0.26 vs. X10 + 0.32, AX -0.41 in patients who continued therapy. This 12-month study shows that many pwCF receiving CFTRm discontinue maintenance therapies, particularly inhaled treatments, without major worsening of lung function. However, changes in small airway function after bronchodilator withdrawal warrant further investigation. These results support the need for long-term prospective studies to guide safe reduction of maintenance therapies in CF.