We conducted a randomized, double-blind, placebo-controlled trial to evaluate ivacaftor (VX-770), a CFTR potentiator, in subjects 12 years of age or older with cystic fibrosis and at least one G551D-CFTR mutation.
Impact of the deltaF508 mutation in first nucleotide-binding domain of human cystic fibrosis transmembrane conductance regulator on domain folding and structure.
Clinical trials have shown an improvement in lung function, weight and CF pulmonary exacerbation in adults with CFTR-G551D</span> leading to the approval of ivacaftor as a novel CF therapy [1].
One drug, ivacaftor, was recently approved by the US Food and Drug Administration for the approximately 4% of patients with CF who have the G551D gating mutation.
The G551D CFTR mutation is the third most common CF disease-causing mutation, in which the CFTR protein localizes to the epithelial cell membrane but has defective gating.
She was found to have a mutation in the SPINK1 gene, IVS3+184T>A, and one cystic fibrosis-causing mutation (G551D) prompting full gene sequencing of the CFTR, revealing an additional duplication of exon 19.
We randomly assigned 39 adults with cystic fibrosis and at least one G551D-CFTR allele to receive oral VX-770 every 12 hours at a dose of 25, 75, or 150 mg or placebo for 14 days (in part 1 of the study) or VX-770 every 12 hours at a dose of 150 or 250 mg or placebo for 28 days (in part 2 of the study).
We generated G551DCF mice transgenically expressing the human CFTR gene in two tissue compartments previously demonstrated to mediate a CFTR-dependent inflammatory response: lung epithelium and alveolar macrophages.
The most common mutations in CFTR are a deletion of a phenylalanine residue at position 508 (ΔF508-CFTR, 70-80 % of CF phenotypes) and a Gly551Asp substitution (G551D-CFTR, 4-5 % of alleles), which lead to decreased or almost abolished Cl(-) channel function, respectively.
Additive improvement in G551D CFTR-mediated Cl<sup>-</sup> secretion suggests that resveratrol could enhance ivacaftor therapy in these patients and improve CF-related rhinosinusitis.
The potentiator Kalydeco™ (also known as Ivacaftor or VX-770), developed by Vertex Pharmaceuticals, has been recently approved by the US FDA and the European Medicines Agency (EMA) for the treatment of CF patients carrying at least one CFTR allele with the p.Gly551Asp mutation (2-5 % of all patients).
The CF-associated mutation G551D, by introducing a bulky and negatively charged side chain into site 2, completely abolishes ATP-induced openings of CFTR.