OBJECTIVESDupilumab, an anti-IL-4 receptor monoclonal antibody (mAb), was recently approved for the treatment of severe chronic rhinosinusitis with nasal polyps (CRSwNP). The main objective of this study was to assess whether previous exposure to biological treatment affected the clinical outcomes in CRSwNP and asthma patients, treated with dupilumab over time. A collateral secondary objective was to analyse the effects over time of dupilumab in patients with and without aeroallergen sensitization.METHODSSingle-centre retrospective observational study on severe CRSwNP patients treated with dupilumab. Nasal polyp score (NPS), visual analogue scale (VAS) symptom score, sinonasal outcome test (SNOT-22), aeroallergen sensitization, total serum IgE levels, and blood eosinophil counts were assessed at baseline and after 4, 6 and 12 months.RESULTS42 patients were included, 40 (95.2%) had asthma. Twenty-one (50%) patients received dupilumab without prior biological treatment (Group A: naive) and 50% switched to dupilumab from previous biological treatment (Group B: pre-treated). NPS, VAS symptoms, SNOT-22 improved significantly after 12 months treatment in both groups of patients (p < 0.001). After 12 months, VAS overall symptom score showed a significant reduction from 6 (IQR, 4.6-8.6) and 6 (IQR, 3.8-7.1) for Group A and Group B patients respectively, to 1.2 (IQR, 0.8-2.7) and 1.2 (IQR, 0.2-2.5); NPS from 6 (IQR, 4.0-7.0) and 5 (IQR, 3.5-6.0), respectively, to 1 (IQR, 0.0-2.0) and 0 (IQR, 0.0-3.0) and SNOT-22 from 64 (IQR, 56-78) and 71 (IQR, 47.5-76.0) respectively, to 5.5 (IQR, 4-21) and 6 (IQR, 4-15). IgE reduced from 57 to 22.1 and from 46.9 to 30.2 in Group A and Group B respectively (p < 0.001).CONCLUSIONSDupilumab improves symptom severity, polyp size, and health-related quality of life, regardless of the presence or absence of comorbid aeroallergen sensitization and previous administration of biologic therapy.