Ivacaftor [VX-770, N-(2,4-Di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide] is a selective small molecule CFTR modulator that targets the 3rd most common genetic mutation in the CFTR gene (G551D – Class III – gating mutation, occurring in 5–6% of people with CF) (Clancy et al. 2014; Fohner et al. 2017). Here, CFTR is linked to cystic fibrosis.