Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a complex chronic inflammatory disease of the nasosinusal mucosa that has a significant negative impact on patients' quality of life.

In CRSwNP, chronic inflammation is primarily driven by type 2 pro-inflammatory interleukins (ILs )such as IL-5, IL-4, and IL-13 along- side high levels of eosinophils in the surrounding tissue. Mepolizumab is a targeted, humanized anti-IL-5 antibody that prevents IL-5 from binding to its receptor on eosinophils and selectively inhibits eosinophilic inflammation.

So far, randomized clinical trials have assessed efficacy and safety of Mepolizumab in a large number of patients, whereas evidences in real life clinical practice are limited to few monocentric series.

Herewith, we present a multicenter, observational, prospective/retrospective nationwide real-life study with the aim to confirm the effectiveness and the safety of Mepolizumab over the first year of treatment in a real life setting.

The primary objective of this study is to evaluate the reduction of dimension of nasal polyps and the improvement of quality of life in the patient measured through symptomatologic questionnaires.

The secondary objective is to evaluate improvements in terms of smell dysfunction, comorbidities, biomarkers (nasal cytology and blood eosinophilia), need of surgery or systemic steroids.

Inclusion Criteria:

• Patients over 18 years of age who can sign a written informed consent Confirmed clinical / radiological diagnosis of chronic rhinosinusitis with diffuse naso-sinusal polyposis by nasal endoscopy and/or massive facial CT scan without contrast medium carried out within 6 months prior to the start of therapy;
• Blood eosinophils >150
• Severe disease stage, defined by Nasal Polyp Score (NPS) ≥ 5 or nasal obstruction symptom visual analogue scale (VAS) score of >5 and/or Sinonasal outcome tests-22 (SNOT-22) ≥ 50);
• Inadequate symptom control with intranasal local corticosteroid therapy;
• Failure of previous medical treatments (at least 2 cycles in the last year of systemic corticosteroid) and failure of previous surgical treatment through nasal endoscopic surgery (FESS), with no clinical benefit or postoperative complications.

Exclusion Criteria:

• Age <18 years;
• Patients undergoing immunosuppressive therapies;
• Patients undergoing radio/chemotherapy treatments for cancer in the 12 months before the start of therapy;
• Patients on concomitant long-term corticosteroid therapy for chronic autoimmune disorders.

We included all patients that were referred to Mepolizumab therapy, prescribed accordingly to the plan provided by AIFA