Safety of the Selective JAK1 Inhibitor Oclacitinib in Dogs

Apoquel(oclacitinib maleate) as a film-coated tablet, a selective Janus kinase (JAK)1 inhibitor, was approved by the United States Food and Drug Administration (FDA) in 2013 for the control of pruritus associated with allergic dermatitis and control of atopic dermatitis in dogs at least 12 months of age. The goal of this review is to describe the safety of oclacitinib in dogs based on data from investigational laboratory and field studies, independent directed studies, and an extensive postmarketing pharmacovigilance (PV) surveillance program. The safety of oclacitinib has been extensively evaluated in investigational and independent studies. In the oclacitinib postapproval PV surveillance, the types and rank order of frequency of reported adverse events were similar to the premarketing field studies, with diarrhea, anorexia, and lethargy being the most frequently reported adverse events. In the postmarketing PV continuous monitoring, adverse events for patients receiving oclacitinib are rarely reported and the individual clinical signs within the PV adverse event reports were considered "very rare" in frequency. An age- and breed- matched retrospective cohort study in dogs with allergic dermatitis showed no significant difference in incidence of neoplasia between dogs treated with oclacitinib and dogs treated with other systemic therapies. The extensive investigational and PV experience with oclacitinib shows that long-term or lifelong use per label instructions has a positive benefit-risk profile and is not associated with any cumulative safety risk.