Tapering of biologics in chronic rhinosinusitis with nasal polyps

Who can take part

• ≥18 years of age. • Currently receiving treatment with either Dupilumab (300 mg) or Mepolizumab (100 mg) every four weeks. • Having received the biologic at unchanged dosing interval for at least three months. • For at least 1 year during treatment with biologics, the patients’ CRSwNP must be categorized as either "controlled" as defined by presence of none of the following 7 items, or as “partly controlled” as defined by presence of 1-2 of the following 7 items (see EPOS 2020 table in protocol): 1. Nasal blockage: present on most days of the week 2. Rhinorrhoea/postnasal drip: mucopurulent on most days of the week 3. Facial pain/pressure1: present on most days of the week 4. Sense of smell: impaired 5. Sleep disturbance or fatigue1: present 6. Nasal endoscopy: diseased mucosa 7. Rescue treatment (systemic corticosteroids, ESS, antibiotics): need of 1 course of rescue treatment

Who cannot take part

• Patients with no or limited response to biologics (“uncontrolled” in EPOS table in the protocol) • Patients with a cancer diagnosis deemed by the investigator to preclude participation in the trial • Patients who, because of language barriers, are not able to understand Danish written information and, thus, are not able to answer questionnaires • Patients who currently receive biologics for any other disease (asthma not included) • Patients who are not able to give informed consent (i.e., patients who are permanently incapable) • Patients who are not eligible because of the investigator’s judgement • Patients who experience pregnancy during the study will be excluded after an unscheduled visit – active IVF treatment (please see the protocol) • Unwillingness to follow the study procedure