CFTR and cystic fibrosis: CFTR modulators act by chemically correcting CFTR activity in CF cells and the most recent therapy approved for clinical use, Kaftrio (aka Trikafta; elexacaftor-tezacaftor-ivacaftor) was shown in phase 3 clinical trials to induce a 14.3% increase in predicted lung function (FEV1) and a 63% reduction in the rate of pulmonary exacerbation at 24 weeks, in patients heterozygous for F508del and a minimal-function mutation relative to the placebo control group (54).