Journal Scan: Examining the efficacy of a new drug for the treatment of atopic dermatitis
Why they did it
Oclacitinib is a Janus kinase inhibitor that decreases inflammatory mediators as well as cytokines that cause pruritus. While the drug has been approved for use in dogs with allergic dermatitis, the goal of this study was to determine if it is a safe and effective alternative for the treatment of atopic dermatitis in dogs.
What they did
Overall, 299 client-owned dogs with a diagnosis of chronic, nonseasonal atopic dermatitis were enrolled in the study. Dogs were randomized in a 1:1 ratio into one of two treatment groups: placebo or oclacitinib (0.4 to 0.6 mg/kg) given orally twice a day for the first 14 days then once a day until day 112. Clinicians and owners were unaware of the treatment group assignments. Response to therapy was based on the Owner Pruritus visual assessment scale (VAS) as well as the dermatologist’s assessment of the Canine Atopic Dermatitis Extent and Severity Index-02 (CADESI-02). “A treatment success for Owner Pruritus VAS was defined as at least a 2 cm reduction (on the 10-cm VAS) from baseline at the day of assessment; a treatment success for clinician’s CADESI-02 was defined as 50% or greater score reduction from baseline at the day of assessment (days 28, 56, 84 and 112).”
What they found
Baseline clinical signs, CADESI-02 scores, and demographics were similar between the two groups. Among dogs in the placebo group, 108/147 (73%) withdrew on or before day 16 of the study because of worsening clinical signs of atopic dermatitis compared with 13/152 (9%) of dogs treated with oclacitinib. Most of the placebo-treated dogs went on to enroll in an open-label study of the drug.
By day 28, 66% of oclacitinib-treated dogs showed improvement in the Owner Pruritus VAS compared with four in the placebo group (P < 0.0001). This response rate remained steady throughout the study period. Based on clinician’s CADESI-02 scores, 49% of oclacitinib-treated dogs showed improvement compared with 4% of placebo-treated dogs (P < 0.0001).
Health events associated with the drug were difficult to compare between groups given the low number of dogs in the placebo group at the end of the study. During the first 16 days, the rate of adverse events overall was low (<5%) and included diarrhea, vomiting, and lethargy that resolved spontaneously in 90% of cases and did not require discontinuation of therapy. Anorexia was the only adverse event noted more often among the oclacitinib group compared with placebo (2.6% vs. 0%, respectively).
While still within reference ranges, mean serum globulin and mean white blood cell, neutrophil, eosinophil, and monocyte counts decreased among dogs in the oclacitinib group by day 14. Among dogs in the oclacitinib group, one dog withdrew from the study because of the development of severe pyoderma (after day 19) and one dog withdrew because of the development of generalized demodicosis (after day 28). Another dog required hospitalization for the diagnosis and treatment of pneumonia (after 91 days), and one dog was hospitalized for cystitis secondary to urolithiasis (after day 80 of therapy).
While further studies are certainly warranted, these early results show that oclacitinib may result in a rapid reduction in pruritus as well as improvement in lesion scores in dogs with atopic dermatitis. The drug appears to be well-tolerated, but the low number of patients in the placebo group made comparison between the groups difficult.
Cosgrove SB, Wren JA, Cleaver DM, et al. A blinded, randomized, placebo-controlled trial of the efficacy and safety of the Janus kinase inhibitor oclacitinib (Apoquel) in client-owned dogs with atopic dermatitis. Vet Dermatol 2013;24:587-597.
Link to abstract: http://onlinelibrary.wiley.com/doi/10.1111/vde.12088/full