This is a Phase 2, randomized, double-blind, placebo- and active-controlled, parallel group, multicenter study to evaluate the safety, tolerability, and efficacy of VX-440 in dual and triple combination with tezacaftor (TEZ; VX-661) and ivacaftor (IVA; VX-770) in subjects with cystic fibrosis (CF) who are homozygous for the F508del mutation of the CF transmembrane conductance regulator (CFTR) gene (F508del/F508del), or who are heterozygous for the F508del mutation and a minimal function (MF) CFTR mutation not likely to respond to TEZ and/or IVA therapy (F508del/MF).