Anti‐IL‐5 recombinant humanized monoclonal antibody (Mepolizumab) for the treatment of atopic dermatitis

Background: Eosinophils may play an important role in the pathogenesis of atopic dermatitis (AD). Interleukin‐5 is essential for eosinophil growth, differentiation and migration. A monoclonal antibody to human interleukin‐5 (mepolizumab) was developed for atopic diseases. This study was designed to study the effect of mepolizumab in AD. Methods: Two single doses of 750 mg mepolizumab, given 1 week apart, were studied in patients with moderate to severe AD using a randomized, placebo‐controlled parallel group design. The primary endpoint of ‘success’ to treatment was defined as the percentage of patients with at least ‘marked improvement’ after 2 weeks as assessed by the Physician's Global Assessment of Improvement (PGA). Furthermore, SCORing AD (SCORAD), pruritus scoring, number of blood eosinophils and serum thymus and activation‐regulated chemokine (TARC) values served as secondary endpoints. Fluticason propionate cream 0.05%, once daily could be used as rescue medication from day 16 if no improvement was recorded. Results: Eighteen patients received mepolizumab and 22 placebo treatment. Peripheral blood eosinophil numbers were significantly reduced in the treatment group compared with placebo ( P < 0.05). No clinical success was reached by PGA assessment ( P = 0.115), SCORAD ( P = 0.293), pruritus scoring and TARC values in the mepolizumab‐treated group compared with placebo. However, modest improvement (<50% improvement) assessed by PGA was scored significantly more in the mepolizumab‐treated group compared with placebo ( P < 0.05). Conclusion: Two single doses of 750 mg mepolizumab did not result in clinical success in patients with AD, despite a significant decrease in peripheral blood eosinophils.