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. Fluticasone 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.