Lumacaftor (Vx-809) is a CFTR corrector, and it was the second treatment to be approved for use in CF therapy, though it can only be used in conjunction with Ivacaftor, a potentiator that improves channel function; also, it has been shown to be safe with biological activity in a Phase IIa clinical trial [19]. This evidence concerns the gene CFTR and cystic fibrosis.