[Elexacaftor, Tezacaftor and Ivacaftor: immediate efficacy evaluation using home spirometry]

Following two weeks of application of the triple combination therapy of Elexacaftor (E), Tezacaftor (T), and Ivacaftor (I) known as ETI, substantial pulmonary improvement in patients with cystic fibrosis is well-documented. However, few detailed data are available on the action of this treatment over the course of these first 14 days.

In this prospective study (NCT05599230), 20 patients aged≥12 years, all of them eligible for ETI, were recruited at the initiation of treatment. Home spirometry (MIR Spirobank®) was performed during the three days preceding the start of treatment and then daily for 14 days, while a respiratory symptom score (RSS) was calculated and a log maintained concerning the events experienced by each patient.

Mean age (± SD) of the 20 patients was 29.4 (± 11.1) years, mean FEV1 was 84.2% (± 17.7), and the mean BMI z-score was 0.18 (± 0.82). Thirteen of them were already on modulators. When compared to the average scores recorded for the three days preceding the start of treatment, FEV1 improvement became significant from the 6th day (D6). After having significantly worsened on D1 (P<0.05), the RSS improved from D6 onwards. The quality of home FEV1 measurements was high (grade A: 81.2%).

Under ETI treatment, respiratory benefits were significant from D6. The side effects most commonly perceived by the patients occurred during the first four days of treatment. While daily monitoring of home spirometry could indeed be a valuable tool in follow-up of patients with cystic fibrosis, its administration requires suitable and sustained training.