Topical anti-microbial peptide omiganan recovers cutaneous dysbiosis but does not improve clinical symptoms in patients with mild-to-moderate atopic dermatitis in a phase 2 randomized controlled trial.

ABSTRACT Background Dysbiosis and colonization with Staphylococcus aureus is considered to play an important role in the pathogenesis of atopic dermatitis (AD). Recovering this dysbiosis may improve AD symptoms. Omiganan is a synthetic indolicidin analogue antimicrobial peptide with activity against S. aureus and could be a viable new treatment option for AD. Objective To explore the tolerability, clinical efficacy and pharmacodynamics of omiganan in mild-to-moderate AD. Methods Eighty patients were randomized to omiganan 1%, 1.75%, 2.5% or vehicle twice daily for 28 days on all lesions. Weekly visits included clinical scores, and microbiological and pharmacodynamic assessments of one ‘target lesion’. Results In all omiganan treatment groups dysbiosis was recovered by reducing Staphylococcus abundance and increasing diversity. A reduction of cultured S. aureus was observed in all omiganan treatment groups, with a significant reduction for omiganan 2.5% compared to vehicle (-93.5%, 95%CI=-99.2%/-28.5% p=0.02). No significant clinical improvement was observed. Conclusion Topical administration of omiganan twice daily for up to 28 days in patients with mild-to-moderate AD led to a recovery of dysbiosis, but without clinical improvement. Therefore, a mono-treatment that selectively targets the microbiome does not appear to be a successful treatment strategy in mild-to-moderate AD.