VX18-445-109 study group 2021, ' Efficacy and safety of elexacaftor plus tezacaftor plus ivacaftor versus tezacaftor plus ivacaftor in people with cystic fibrosis homozygous for F508del-CFTR: a 24-week, multicentre, randomised, double-blind, active-controlled, phase 3b trial ', The Lancet. Respiratory medicine . https://doi.org/10.1016/S2213-2600(21)00454-9