This restoration of chloride secretion is comparable to that achieved in F508del-CFTR homozygous patient cells treated with the potentiator CF drug VX-770 and C18 (an analog of the corrector CF drug VX-809), a drug combination mimicking the clinically-approved treatment (VX-770+VX-809) currently used to treat CF patients with the F508del mutation. This evidence concerns the gene CFTR and cystic fibrosis.