Interleukin 5 (IL-5) has been shown to play an instrumental role in eosinophilic inflammation in allergic diseases. The purpose of this review is to explore clinical trials of anti-IL-5 antibody therapy that have been conducted in patients with asthma, hypereosinophilic syndromes, eosinophilic esophagitis, atopic dermatitis, Churg-Strauss syndrome, and nasal polyposis.

RECENT FINDINGS: Recent trials of anti-IL-5 in patients with severe asthma refractory to existing therapies and prominent sputum eosinophilia experienced significant reductions in asthma exacerbations. Studies in patients with hypereosinopihilic syndromes have shown that IL-5 antagonism allows significant reductions in systemic corticosteroid doses while maintaining or improving blood eosinophil counts and symptoms. In children and adults with eosinophilic esophagitis, anti-IL-5 treatment reduced eosinophil numbers in esophageal tissue; it is uncertain whether these findings are predictive of clinical improvement. Clinical studies of individuals with atopic dermatitis do not support efficacy of anti-IL-5 in either reducing allergen patch test intensity or symptoms of chronic dermatitis. In small trials in both Churg Strauss syndrome and nasal polyposis, anti-IL-5 shows promise but larger numbers of patients with these conditions will need to be studied.

SUMMARY: Anti-IL-5 is efficacious in treating patients with severe asthma and sputum eosinophilia and hypereosinophilic syndromes. Larger controlled trials with appropriate endpoints will be necessary to assess the role of anti-IL-5 in other eosinophilic disorders.