An Observational Study of Outcomes and Tolerances in Patients with Cystic Fibrosis Initiated on Lumacaftor/Ivacaftor.

RATIONALE

In July 2015, the U.S. Food and Drug Administration approved lumacaftor/ivacaftor for use in patients with cystic fibrosis (CF). This drug targets the primary defect in the CFTR protein that is conferred by the F508del CFTR mutation.

OBJECTIVE

As there is limited experience with this therapy outside of clinical trials, this study aims to examine the clinical experience of this new drug in a population with CF.

RESULTS

Retrospective cohort study of individuals followed at the Johns Hopkins CF Center who initiated treatment with lumacaftor/ivacaftor. Patients were followed from 1 year before drug initiation to up to 11 months postinitiation. Key exclusion criteria include previous exposure to lumacaftor/ivacaftor through participation in a clinical trial. Of 116 individuals identified who started lumacaftor/ivacaftor treatment, 46 (39.7%) reported adverse effects related to lumacaftor/ivacaftor, with the vast majority (82.2%) being pulmonary adverse effects, and 20 (17.2%) discontinued lumacaftor/ivacaftor because of adverse effects. The mean change in FEV% predicted was 0.11% (range: -39% to +20%; P = 0.9). Nineteen individuals had an FEV% predicted of 40% or less before treatment, and there was a higher percentage of patients in this subgroup who reported adverse effects (57.9%) and a higher percentage of patients who discontinued lumacaftor/ivacaftor (31.6%). Female sex was associated with a higher odds of drug discontinuation (adjusted odds ratio, 3.12, 95% confidence interval, 1.04-9.38).

CONCLUSIONS

This study highlights the prevalence of adverse effects in a CF population newly exposed to lumacaftor/ivacaftor and demonstrates a relatively high rate of drug intolerance.