OBJECTIVES The primary objective of this study is evaluating the reduction of dimension of nasal polyps measured with Nasal Polyp Endoscopic Score (NPS) The secondary objective is to evaluate the improvement in nasal symptoms and quality of life in the patient measured through symptom questionnaires, the improvements in terms of smell dysfunction and symptomatology related to eosinophilic otitis media;evaluate the need of surgery or systemic corticosteroids.

ENDPOINTS Primary endpoint The primary endpoints will be the Improvement of NPS score (indicative of polyps score reduction) at 12 months after start of therapy.

Secondary endpoints

• Improvement of SNOT-22 score (indicative of an improvement in quality of life)
• Improvement of VAS score for nasal obstruction
• Improvement of Nasal Congestion Score (NCS)
• Improvement of VAS score for smell;
• Improvement of sniffin' sticks score;
• Evaluate adherence to drug therapy with Mepolizumab 300, any suspension of the same and reasons for discontinuing treatment (lack of efficacy, complications reported, safety profile);
• Assess how many patients require FESS surgery and/or systemic steroids for sino-nasal symptoms during treatment;
• Evaluate the improvement of symptoms of any associated comorbidities and in particular chronic eosinophilic otitis media.

Study design Observational, retrospective/prospective, non-profit and national multicenter real-life study.

Population. patients affected by EGPA and concomitant severe chronic rhinosinusitis with nasal polyps (CRSwNP) not controlled by local and systemic corticosteroids and/or surgery, who have received indication, during normal clinical practice, to therapy with Mepolizumab 300mg every 4 weeks (self-administered at home with subcutaneous autoinjector), in addition to topical nasal corticosteroids.

Duration of the study The foreseen study duration is of 18 months since the approval of the present protocol by the Local Ethics Committee.

Inclusion criteria

Eligible patients will be:

• Patients over 18 years of age who can sign a written informed consent;
• Confirmed diagnosis of EGPA by rheumatologist and in treatment with Mepolizumab 300 mg every 4 weeks, according to clinical pratice;
• 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;
• Severe disease stage, defined by Nasal Polyp Score (NPS) ≥ 5 or nasal obstruction symptom visual analogue scale (VAS) score of >5 and/or 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) or failure of previous surgical treatment through nasal endoscopic surgery (FESS), with no clinical benefit or postoperative complications.

Exclusion criteria

• Age <18 years;
• Patients with EGPA with organ impairment or at risk of death;
• Patients undergoing radio/chemotherapy treatments for cancer in the 12 months before the start of therapy.

Procedures All patients eligible for biological therapy will require adiagnostic work-up" according to the current guidelines (EPOS2020 and EUFOREA). According to clinical practice, patients first must have performed a CT and/or endoscopic examination to confirm the diagnosis of severe diffuse chronic rhinosinusitis with nasal polyps and allow for a staging of the disease through the application of specific and validated endoscopic scores (e.g., Nasal Polyps Score) and radiological scores (e.g., Lund Mackay score). EPOS and EUFOREA also recommend an accurate medical history collection, focusing on the main clinical features (family history of chronic rhinosinusitis, concomitant respiratory diseases, intolerance to NSAIDs, allergies, blood hyper-eosinophilia) before starting therapy, as clinical practice.

The medical history should be sensitized by administration of questionnaires specific for nasal symptoms and quality of life and, in particular, SNOT-22 administration is largely recommended. SNOT-22 is world-wide used in common clinical practice for patients with diffuse nasal polyposis during the evaluation to the eligibility for biological therapy. It consists of two parts, one more specific for the assessment of nasal symptoms, and a second focused on the quality of life and any comorbidities associated with nasal polyps. As for the evaluation of nasal symptom (i.e. nasal obstruction, rhinorrhea, craniofacial pain, etc.) the visual analogue scale (VAS) can alternatively be used, with a score ranging from 0 to 10. Other questionnaires widely used in clinical practice are the one on nasal congestion symptoms (NCS - Nasal congestion score) and the visual analogue scale related to the subjective loss of smell. The guidelines also recommend to routinely assess the olfactory sensitivity in a semi-objective manner. To this aim, the test currently used at national level is the subjective olfactometry using "Sniffin' Sticks", and in particular the identification test, which consists of 16 sticks filled in with odorous substances.

For the evaluation of asthma and its symptoms, the guidelines instead recommend to use of ACT (Asthma Control Test) questionnaire.

Patients receiving Mepolizumab 300 are generally evaluated in normal clinical practice at baseline and 30 days after first administration for an early re-evaluation. Subsequently, follow-up is continued with clinical re-evaluation every 3 months in the first year of treatment. Retrieve the clinical data of the visits performed at 30 days since the beginning of therapy and at 3,6,9 and 12 months is required.

Data about any discontinuation of Mepolizumab due to adverse effects, intolerance to the drug, or related to its inefficacy and sino-nasal surgical treatment during treatment will be collected.

Inclusion criteria

Eligible patients will be:

• Patients over 18 years of age who can sign a written informed consent;
• Confirmed diagnosis of EGPA by rheumatologist and in treatment with Mepolizumab 300 mg every 4 weeks, according to clinical pratice;
• 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;
• Severe disease stage, defined by Nasal Polyp Score (NPS) ≥ 5 or nasal obstruction symptom visual analogue scale (VAS) score of >5 and/or 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) or failure of previous surgical treatment through nasal endoscopic surgery (FESS), with no clinical benefit or postoperative complications.

Exclusion criteria

• Age <18 years;
• Patients with EGPA with organ impairment or at risk of death;
• Patients undergoing radio/chemotherapy treatments for cancer in the 12 months before the start of therapy.

We will collect data from patients affected by EGPA and concomitant severe chronic rhinosinusitis with nasal polyps (CRSwNP) not controlled by local and systemic corticosteroids and/or surgery, who have received indication, during normal clinical practice, to therapy with Mepolizumab 300mg every 4 weeks (self-administered at home with subcutaneous autoinjector), in addition to topical nasal corticosteroids.

For the retrospective cohort, the start of observation is from 01 March 2023 We be enrolled 52 patients.