Outcomes of Modulator Therapy Discontinued After Short-Term Use in Adult Cystic Fibrosis.

Introduction: Cystic fibrosis transmembrane conductance regulator modulator therapies (CFTR-MT) have altered management, reducing exacerbations and slowing pulmonary function decline. Nevertheless, it is still uncertain if the benefits of CFTR-MTs last when they are stopped. This study aimed to assess pulmonary function changes, and exacerbation rates during and after CFTR-MT use in adult cystic fibrosis patients.

Methods: Between 2018 and 2022, we conducted a study involving adult CF patients who initially used CFTR-MTs but later discontinued them due to reimbursement issues. The study was divided into three phases: predrug (T1), in-drug (T2), and postdrug (T3). We recorded pulmonary function tests, laboratory and culture results, and the number of exacerbations.

Results: The study involved 33 patients, with 28 (84.8%) receiving Elexacaftor/Tezacaftor/Ivacaftor and 5 (15.2%) receiving Ivacaftor. The median treatment and interruption durations were 3.1 (IQR = 2.9-5.7), and 2.5 (IQR = 1.5-4.0) months, respectively. The mean FEV1% was 54.3% (± 26.6), 70.4% (± 27.4), and 60.2% (± 26.5) during T1, T2, and T3, respectively (p < 0.001). The mean FVC% was 65.5% (± 23.9) in T1, increased to 81.5% (± 24.5) in T2, and decreased to 71.6% (± 25.9) in T3 (p < 0.001). The number of Psedomonas aeruginosa, and Aspergillus positive sputum cultures decreased significantly with drug use (T1: 72.7%, 39.4%; T2: 48.5%, 9.1%; T3: 45.5%, 18.2%; p = 0.014, p = 0.004, respectively). The median number of hospitalizations was 1.0 (0-5.0) in T1, 0 (0-0) in T2, and 0 (0-1.0) in T3.

Conclusion: This study revealed that CFTR-MTs are effective even in the short term for adult CF patients, but their beneficial effects quickly diminish after discontinuation. Real-life data obtained as a result of discontinuation of drugs due to reimbursement problems has highlighted the significance of regular and uninterrupted use of modulators.