This is a prospective, open-label, multicenter study (1 year) with 50 patients with cystic fibrosis for whom treatment with KAFTRIO® is prescribed.Cystic fibrosis is a rare autosomal recessive hereditary disease linked to a mutation of the CFTR (Cystic Fibrosis Transmembrane Regulator) protein gene. For the majority of patients, no treatment with a CFTR protein modulator was available until the arrival of the KAFTRIO® triple therapy (ivacaftor/tezacaftor/elexacaftor). Clinical studies on this triple therapy demonstrate significant improvements in FEV (forced vital capacity) and also very rapid health improvement of patients. However, there is a lack of data recorded in real life at home by patients to trace the evolution curves of health parameters and patient perceptions from the first days after initiation of treatment. The PHEAL-CR-K application, specially developed for the study, makes it possible to collect physiological parameters and perceptions collected via connected objects or declared manually in the application. These data will reflect the evolution of the parameters from the start of the treatment and over a period of 3 months. In addition, the composition of volatile organic compounds (VOCs) of the air exhaled in the early phase of treatment with KAFTRIO® will be monitored for the group of patients followed at Foch Hospital. Exhaled air is an ideal biological fluid for clinical monitoring (non-invasive collection and real-time analysis). In cystic fibrosis, biomarkers in the exhaled air have been correlated with functional and clinical parameters. The objective is to collect the air exhaled before initiating treatment with KAFTRIO® and during treatment, to identify VOCs whose expression would be modified early. Changes in the composition of the exhaled air will be correlated with follow-up clinical data collected with the PHEAL-CR-K application and with functional data obtained during measurements of breath by spirometry (FEV) and sweat concentrations of chloride ions collected at the during a sweat test. The identified COVs could become early predictive biomarkers of clinical response.

Inclusion Criteria:

• Patients aged 18 and over
• Patients with Cystic Fibrosis eligible for KAFTRIO®
• Patients for which KAFTRIO® treatment is prescribed, including patients previously treated with other CFTR modulators (ORKAMBI®, KALYDECO®, SYMKEVI®)
• Patients who signed the informed consent form
• Patients affiliated to a health insurance plan
• Patients equipped with a smartphone and having a Wifi connection at home

Exclusion Criteria:

• Pregnant or breastfeeding women
• Patient who does not speak or understand French
• Patient deprived of liberty or under guardianship