CFTR and cystic fibrosis: Moreover, additive effects of Corr-4a and VX-809 combination were also reported in ΔF508 CFTR homozygous human primary bronchial epithelial cells [18], as well as in CFBE41o- cells expressing ΔF508 CFTR and organoid samples derived from CF patients homozygous for ΔF508 mutation [16], supporting the idea that Corr-4 has corrector capability.