A blinded, randomized, placebo‐controlled, dose determination trial of lokivetmab ( ZTS ‐00103289), a caninized, anti‐canine IL ‐31 monoclonal antibody in client owned dogs with atopic dermatitis

Background Pruritus is the hallmark clinical sign of atopic dermatitis ( AD ) in dogs. Lokivetmab, a caninized anti‐canine IL ‐31 monoclonal antibody, reduced pruritus and associated inflammatory skin lesions in a proof‐of‐concept study in dogs with AD . Hypothesis/Objectives The objective was to describe lokivetmab dose response in a randomized, double blind, placebo‐controlled trial. Animals Clinicians at 15 referral clinics enrolled 211 client owned dogs with a history of chronic AD . Methods Dogs were randomized to treatment with lokivetmab (0.125, 0.5 or 2.0 mg/kg) or placebo administered subcutaneously once on Day 0. Dog owners assessed visual analog scale ( VAS ) scores of pruritus on days 0, 1, 2, 3, 7, 14, 21, 28, 35, 42, 49 and 56. Clinicians assessed Canine AD Extent and Severity Index ( CADESI ‐03) scores on days 0, 7, 14, 28, 42 and 56. Results Treatment with lokivetmab (2 mg/kg) resulted in a greater percentage reduction from baseline in owner assessed pruritus (days 1–49) and clinician assessed CADESI ‐03 scores (days 7–56) compared to placebo ( P < 0.05 ); differences were achieved in lower dose groups but at later time points and for shorter duration for both owner assessed pruritus (0.5 mg/kg, days 2–35; 0.125 mg/kg, days 7–21) and clinician assessed CADESI ‐03 scores (0.5 mg/kg and 0.125 mg/kg, Day 14). Conclusions and clinical importance Lokivetmab (0.5, 2.0 mg/kg) reduced pruritus compared to placebo for at least 1 month. Level and duration of response increased with increasing dose. Further studies are needed to better understand variability in individual responses across a broader population of dogs with AD .