Efficacy response in CF patients treated with ivacaftor: post-hoc analysis

Pediatr Pulmonol. 2015 May;50(5):447-55. doi: 10.1002/ppul.23173. Epub 2015 Mar 9.


Clinical studies in patients with cystic fibrosis and G551D-CFTR showed that the group treated with ivacaftor had improved clinical outcomes. To better understand the effect of ivacaftor therapy across the distribution of individual FEV(1) responses, data from Phase 3 studies (STRIVE/ENVISION) were re-examined. In this post-hoc analysis of patients (n = 209) who received 48 weeks of ivacaftor or placebo, patients were assigned to tertiles according to FEV(1) response. These groups were then used to evaluate response (FEV(1), sweat chloride, weight, CFQ-R, and pulmonary exacerbation). The number needed to treat (NNT) was calculated for specific thresholds for each outcome. Across all tertiles, numerical improvements in FEV(1), sweat chloride, CFQ-R and the frequency of pulmonary exacerbations were observed in ivacaftor-treated patients: the treatment difference versus placebo was statistically significant for all outcomes in the upper tertile and for some outcomes in the lower and middle tertiles. The NNT for a ≥ 5% improvement in %predicted FEV(1) was 1.90, for a ≥ 5% body weight increase was 5.74, and to prevent a pulmonary exacerbation was 3.85. This analysis suggests that the majority of patients with clinical characteristics similar to STRIVE/ENVISION patients have the potential to benefit from ivacaftor therapy.

Keywords: CFTR; clinical response; cystic fibrosis; ivacaftor.

Publication types

  • Clinical Trial, Phase III
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aminophenols / therapeutic use*
  • Child
  • Chlorides / analysis
  • Cystic Fibrosis / drug therapy*
  • Cystic Fibrosis / genetics
  • Cystic Fibrosis / physiopathology
  • Cystic Fibrosis Transmembrane Conductance Regulator / genetics
  • Disease Progression
  • Female
  • Forced Expiratory Volume
  • Humans
  • Male
  • Mutation
  • Numbers Needed To Treat
  • Quinolones / therapeutic use*
  • Respiratory Function Tests
  • Surveys and Questionnaires
  • Sweat / chemistry
  • Weight Gain
  • Young Adult


  • Aminophenols
  • CFTR protein, human
  • Chlorides
  • Quinolones
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • ivacaftor