Dynamics of lung function and inflammatory parameters after initiation of Elexacaftor/Tezacaftor/Ivacaftor treatment in children with cystic fibrosis

Introduction: The early dynamics of physiological and inflammatory responses to cystic fibrosis transmembrane conductance regulator (CFTR) modulator treatment remain poorly understood. Understanding these dynamics is important for clinical monitoring and early treatment evaluation. Aims: We aimed to compare early changes in lung function with changes in inflammatory parameters following the initiation of Elexacaftor/Tezacaftor/Ivacaftor (ETI) in children with cystic fibrosis (CF). Methods: This is a multi-centre, prospective observational study of children aged 2.6-17.6 years conducted across three CF centres in Switzerland (Geneva, Lausanne, Lucerne). Standardized measurements were performed within 2 months prior to ETI initiation and at 7–14 days, 3 months and 12 months post-treatment. Depending on variable distribution, repeated-measures analysis of variance (ANOVA) or Friedman tests were used, with Bonferroni corrected post hoc analyses. Results: Seventy-two patients [mean (SD) age: 10.8 (3.7) years; 50% male] initiated ETI treatment. We observed significant improvements within 7–14 days for forced vital capacity from 2.5 litres (97.3%,−0.24 z-score) to 2.6 litres (101.7%, 0.12 z-score) (p