CFTR and cystic fibrosis: In this study, we sought to demonstrate that the treatment combination ivacaftor-lumacaftor (Orkambi®) was able to correct the CFTR-dependent chloride efflux in CF people homozygous for F508del. Overall, the data presented in this study support the notion that CFTR-dependent chloride efflux in MNCs should be investigated as a sensitive outcome measure of Orkambi® treatment in CF patients.