Ataluren in nonsense mutation cystic fibrosis patients not receiving chronic inhaled tobramycin: Evaluation of exacerbations and lung function

Introduction Ataluren functions by interacting with ribosomes to promote read-through of nonsense mutations in CF. Ataluren9s activity was shown to be inhibited by certain aminoglycosides such as tobramycin that also bind to the ribosome. Aim To investigate the effect of ataluren on lung function (LF) and pulmonary exacerbations. Methods A post-hoc analysis was performed on a recent randomized, double-blind, placebo-controlled, phase 3 study to determine the efficacy and safety of ataluren in patients with nonsense mutation cystic fibrosis (nmCF) (Kerem E, et al. Lancet Respir Med. 2014;2:539-47) on %-predicted FEV 1 (ppFEV 1 ) and exacerbations by use of chronic inhaled tobramycin at baseline. Results Patients not receiving chronic inhaled tobramycin (non-TOBI; n=146), showed a 5.7% difference in relative ppFEV 1 between ataluren and placebo (−0.7% vs −6.4%; p=0.0082) and 40% fewer exacerbations (1.42 vs 2.18; p=0.0061). Non-TOBI patients ≥6 to 1 between ataluren and placebo (4.9% vs −3.3%; p=0.026) and a 60% lower exacerbation rate favoring ataluren (p=0.030). In all intent-to-treat patients (N=232) at week 48, including tobramycin patients, neither relative change from baseline in ppFEV 1 (−2.5% vs −5.5%; p=0.12), nor number of exacerbations (1.42 vs 1.78; p=0.099) significantly differed between ataluren and placebo. Conclusions Ataluren significantly reduced exacerbations and improved LF in nmCF patients not receiving chronic inhaled tobramycin, with markedly improved treatment effect in children and adolescents. Ataluren thus shows promise as a disease-modifying therapy in nmCF.