The trial posting for A Phase II, Multicenter, Double-Blinded, Placebo-Controlled Study to Evaluate Safety, Efficacy, Pharmacokinetics, and Pharmacodynamics of VX-661 Monotherapy and VX-661/Ivacaftor Cotherapy in Subjects with Cystic Fibrosis Homozygous or Heterozygous for the F508del-CFTR Mutation is not listed as active in clinicaltrials.partners.org database. The trial may have stopped recruiting.