CFTR and cystic fibrosis: In a study conducted by Lee T. et al. that involved 468 patients, regarding the annual rate of lung function decline of CF patients on ETI treatment, discovered that on average, pulmonary function was not lost over a two-year period, assessed through a mean annualized rate of change in percent predicted forced expiratory volume in 1 s (ppFEV1), thus demonstrating that CFTR modulator therapy has the potential of stopping lung function decline over an extended period of time in CF patients [15].