VX-770 (Ivacaftor) is a CFTR potentiator and has been shown to potentiate normal CFTR, as well as CFTR with G551D and F508-del mutations. Ivacaftor directly binds to the ion channel, causes conformation change and open the ion channel to improve chloride transportation. In primary cultured human CF bronchial epithelia (HBE) carrying the G551D and F508del CFTR mutations, Ivacaftor (10 ?M) potently increases the forskolin-stimulated Cl- secretion with an EC50 of 236 nM. [1]

VX-770 (Ivacaftor) is approved for cystic fibrosis patients with G551D mutation, and has shown efficacy in a patient with S549N mutation. [2]