CHEC-OB-17: CHaractErizing CFTR Modulated Changes in Sweat Chloride and their Association with Clinical Outcomes

Cystic fibrosis (CF) is caused by gene mutations leading to absence or dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) protein which functions as a chloride channel in epithelial cells lining the respiratory tract, gastrointestinal system and sweat glands. Over the past several years, CFTR modulators (small molecule therapies that improve activity of the CFTR protein) have been shown in large clinical trials to improve clinical outcomes in people with CF resulting in the FDA approval of the modulators ivacaftor and lumacaftor/ivacaftor. In clinical trials, SC measurements emerged as an important marker of CFTR activity. The CHEC-SC study is looking at SC levels in people with CF who are currently being treated with CFTR modulator therapies. This study is being done to answer the following questions: • Why do different CF patients have larger or smaller reductions in sweat chloride after treatment with CFTR modulator therapy? • Does the sweat chloride value achieved after treatment with CFTR modulator therapy impact long-term health outcomes in people with CF?