Elexacaftor increases the number of mature CFTR proteins at the cell surface and was first evaluated in combination with TEZ and IVA in a 4-week phase 2 double-blind RCT that recruited CF patients 18 and older, with a ppFEV1 between 40 and 90, homozygous for the F508del mutation or carrying F508del and a minimal function mutation [19]. Here, CFTR is linked to cystic fibrosis.