Real‐World Experience of 3‐Year Treatment With Dupilumab: Significant Decrease in Circulating Neutrophils and Eosinophils in Japanese Patients With Atopic Dermatitis

ABSTRACT Dupilumab, an anti‐interleukin (IL)‐4 receptor α‐antibody, was approved in 2018 for the treatment of moderate‐to‐severe atopic dermatitis (AD) in Japan. Although real‐world data have accumulated on the effectiveness and safety of dupilumab in patients with AD in the short term, real‐world data on its long‐term use are limited. In this study, we retrospectively investigated its effectiveness, safety and laboratory data in patients with AD who received dupilumab for 3 years. All adult patients with moderate‐to‐severe AD who were administered dupilumab between June 2018 and December 2020 and were treated with dupilumab for more than 3 years were included in this study. Sixty Japanese patients with AD (male, 48; female, 12) were included in this study. Their mean age was 36.6 ± 11.0 (standard deviation) years. The mean Eczema Area and Severity Index (EASI) was 29.9 ± 9.2. The clinical severity scales, including Investigator's Global Assessment (IGA), EASI and affected body surface area (BSA), and patient‐reported outcomes, such as Dermatology Quality Life Index (DLQI), Patient‐Oriented Eczema Measure (POEM) and visual analogue scale (VAS) of pruritus, significantly improved at 3 months, and at 1, 2 and 3 years after initiating dupilumab. The total EASI score significantly decreased by a mean of 66.8% at 3 months, 81.0% at 1 year, 85.3% at 2 years and 90.0% at 3 years after initiating dupilumab. The serum levels of thymus and activation‐regulated chemokine (TARC), immunoglobulin E (IgE) and lactate dehydrogenase (LDH) significantly decreased at 1, 2 and 3 years. A slight decrease in circulating neutrophils was observed in patients with AD treated with dupilumab over periods from 3 months to 3 years. The number of circulating eosinophils significantly decreased at 2 and 3 years after initiating dupilumab. The most common adverse event was ocular disorders observed in 23 patients (38.3%). Our study shows the sustained effectiveness and tolerable safety of 3‐year usage of dupilumab in Japanese patients with atopic dermatitis. Furthermore, dupilumab decreased neutrophil values at 3 months and later, and reduced the number of circulating eosinophils after long‐term use (≧ 2 years).