Nanomolar Potency Aminophenyltriazine CFTR Activator Reverses Corneal Epithelial Injury in a Mouse Model of Dry Eye.

Dry eye disorders are a major health care burden. We previously reported the identification of -methyl--phenyl-6-(2,2,3,3-tetrafluoropropoxy)-1,3,5-triazine-2,4-diamine [cystic fibrosis transmembrane conductance regulator (CFTR)-K267], which activated human wild-type CFTR chloride conductance with EC ∼ 30 nM. Here, we report evidence for CFTR-K267 efficacy in an experimental mouse model of dry eye using a human compatible ophthalmic vehicle. CFTR activation in mice was demonstrated by ocular surface potential difference (OSPD) measurements. Ocular surface pharmacodynamics was measured in tear fluid samples obtained at different times after topical administration of CFTR-K267. Dry eye was produced by lacrimal duct cautery (LDC) and corneal epithelial injury and was assessed by Lissamine green (LG) staining. OSPD measurements demonstrated a hyperpolarization of -8.6 ± 3 mV (standard error of the mean, 5 mice) in response to CFTR-K267 exposure in low chloride solution that was reversed by a CFTR inhibitor. Following single-dose topical administration of 2 nmol CFTR-K267, tear fluid CFTR-K267 concentration was >500 nM for more than 6 h. Following LDC, corneal surface epithelial injury, as assessed by LG staining, was substantially reversed in 10 of 12 eyes receiving 2 nmol CFTR-K267 3 times daily starting on day 2, when marked epithelial injury had already occurred. Improvement was seen in 3 of 12 vehicle-treated eyes. These studies provide evidence in mice for the efficacy of a topical, human use compatible CFTR-K267 formulation in stimulating chloride secretion and reversing corneal epithelial injury in dry eye.