Sinonasal microbiome remains stable during dupilumab therapy in chronic rhinosinusitis: a pilot study

PURPOSE: This prospective pilot study aimed to evaluate whether dupilumab therapy induces measurable changes in the sinonasal microbiome of patients with chronic rhinosinusitis with nasal polyps (CRSwNP). METHODS: Eight CRSwNP patients fulfilling criteria for biologic therapy were treated with dupilumab 300 mg biweekly for six months. Nasal swabs from the middle meatus were collected immediately before therapy initiation and after six months. Alpha diversity and beta diversity metrics were assessed, and differential abundance analysis was performed. RESULTS: Dupilumab therapy did not result in significant changes in alpha diversity, beta diversity, or taxonomic composition. Minor, non-significant reductions in richness and Shannon diversity were observed. Principal coordinate analysis showed extensive overlap between pre- and post-treatment samples, supported by a non-significant PERMANOVA. No statistically significant differentially abundant taxa were detected. In contrast to the microbiome results, clinical outcomes improved markedly over the same period, with all patients showing a reduction in SNOT-22 of at least 12 points and a decrease in Nasal Polyp Score of at least 1 point. CONCLUSION: In this pilot CRSwNP cohort, no significant changes in sinonasal microbial diversity or composition were detected over six months of dupilumab therapy, despite marked clinical improvement. Larger, controlled studies are required to detect subtle or delayed microbial changes.