Mepolizumab to CRSwNP Through 12 Months - Randomised to FESS and Non-FESS Within the First 2 Weeks

This clinical trial will compare treatment in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and asthma. The patients will be randomized to treatment with the biologic drug, Mepolizumab, or the biologic drug Mepolizumab combined with Functional Endoscopic Sinus Surgery (FESS).The aim of this study is to evaluate the effect of combined treatment with biologic treatment and surgery vs. biologic treatment only.The hypothesis is that surgical removal of polyps and inflamed tissue from the nasal sinuses will increase the effect of the biologic treatment, leading to a lower disease burden after 6 months of treatment, compared with biologic drugs only. Furthermore, combined biologics and surgery will keep a lower disease burden and better general health after 12 months of treatment than biologics alone.Inclusion criteria:Patients ≥ 18 years old at the time of signed informed consent (no upper limit)Patients who are referred to the outpatient clinic for the following reasons:Doctor's diagnosis of CRSNPS ≥ 2+2 out of a score of 8 (max)Severity measured as an SNOT22 score > 35One FESS in general anaesthesia performed prior to inclusion (no time limitations)No course of systemic steroids within the last 3 months, whereas a daily low dose is allowedPossible doctor's diagnosis of asthmaType 2 inflammationExclusion criteria:Patients who, because of language barriers, are not able to understand written information and, thus, are not able to answer questionnairesPatients who currently receive biologics for any other diseasePatients who have previously or currently received biologics for CRS or asthmaPatients who are not able to give informed consent (i.e., patients who are permanently incapable)Patients who meet ≥1 of the following:Malignant lung diseaseCardiac disease of clinical importanceCurrent pregnancy and breastfeeding, as well as planning to be pregnant in the near futureUnwillingness to have FESS performedPatients needing FESS or systemic steroids (OCS) during the study period will be excluded after an unscheduled visit (last observation carried forward (LOCF))Patients who are not eligible because of the investigator's judgementThe effect of the treatment will be evaluated with objective procedures and questionnaires related to CRSwNP and asthma after 3, 6 and 12 months.

Inclusion Criteria:Patients ≥ 18 years old at the time of signed informed consent (no upper limit)Patients who are referred to the outpatient clinic for the following reasons:Doctor's diagnosis of CRSNPS ≥ 2+2 out of a score of 8 (max)Severity measured as an SNOT22 score > 35One FESS surgery in general anaesthesia performed prior to inclusion (no time limitations)No course of systemic steroids within the last 3 months, whereas a daily low dose is allowedPossible doctor's diagnosis of asthmaType 2 inflammationExclusion Criteria:Patients who, because of language barriers, are not able to understand written information and, thus, are not able to answer questionnairesPatients who currently receive biologics for any other diseasePatients who have previously or currently received biologics for CRS or asthmaPatients who are not able to give informed consent (i.e., patients who are permanently incapable)Patients who meet ≥1 of the following:Malignant lung diseaseCardiac disease of clinical importanceCurrent pregnancy and breastfeeding, as well as planning to be pregnant in the near futureUnwillingness to have FESS performedPatients needing FESS or systemic steroids (OCS) during the study period will be excluded after an unscheduled visit (last observation carried forward (LOCF))Patients who are not eligible because of the investigator's judgement