While the potentiator VX-770 or the CFTR corrector lumacaftor (VX-809) alone did not significantly improve lung function in F508del CF patients [36], combining VX-809 with VX-770 (in the drug Orkambi) or combining the newer corrector tezacaftor (VX-661) with VX-770 (in the drug Symdeko) resulted in only modest lung function improvements in clinical trials in patients homozygous for F508del CFTR [37,38,39,40]. This evidence concerns the gene CFTR and cystic fibrosis.