A topical aqueous calcineurin inhibitor for the treatment of naturally occurring keratoconjunctivitis sicca in dogs

Abstract

The purpose of this study was to evaluate the efficacy of an aqueous calcineurin inhibitor, SCY-641, in the treatment of naturally occurring canine immune-mediated keratoconjunctivitis sicca (KCS). A randomized, double-masked, placebo-controlled clinical study of 56-day duration was performed in dogs with naturally occurring immune-mediated KCS assigned to treatment with either topical twice-daily aqueous calcineurin inhibitor solution (SCY-641) or artificial tears (placebo) by the study administrator. Clinical examination and Schirmer tear tests (STT) were performed prior to therapy and at days 7, 14, 28, and 56 after initiation of treatment. Twenty dogs were enrolled in the study with ten receiving placebo and 10 receiving SCY-641 in one or both eyes. No adverse effects were noted with any treatment. There were no significant differences in mean STT values in dogs in group either at day 0 (prior to therapy) or after 7 days of treatment. At 14, 28, and 56 days after initiation of treatment, mean STT and increase in STT over baseline in dogs treated with SCY-641 were significantly higher than in dogs treated with placebo (P < 0.04). SCY-641 was well tolerated by dogs with naturally occurring KCS, and by 14 days after initiating therapy, dogs treated with SCY-641 had significantly higher STT than placebo-treated dogs. These preliminary results indicate that topical SCY-641, in a stable clear aqueous solution, is efficacious in a spontaneous model of KCS and warrants further evaluation as a treatment of immune-mediated KCS.