A Real-world, Head-to-head Comparison of Dupilumab Versus Mepolizumab in Danish Patients With Chronic Rhinosinusitis With Nasal Polyps

Objectives: * The primary objective is to 1. establish non-inferiority of dupilumab versus mepolizumab, and if that is established, then 2. test for possible superiority of dupilumab over mepolizumab in the following hierarchical order (SNOT-22 - Sniffin' Sticks 16 - NPS - ACQ * The secondary objective is to explore any other relevant differences between mepolizumab and dupilumab in terms of frequency of AEs, need for rescue treatments, diversity in outcome based on endotype or comorbidity or other factors, that can lead to a patient-centred approach, when choosing treatment for CRSwNP. Trial design: A randomized, multi-center non-inferiority trial (phase IV RCT). The trial is unblinded. Investigational medicinal products (IMPs) will be "off-the-shelf" and administered in EMA-approved dosages and -intervals. Trial population: The trial aims to include 220 patients with severe, uncontrolled CRSwNP (110 patients in each treatment group). The patients will be recruited from 9 different sites across Denmark. Treatment in Denmark is 100% subsidized by the state. Methods: Subjects fulfilling inclusion criteria will be randomized 1:1 to either dupilumab or mepolizumab. After 24 weeks a halfway evaluation will decide if subjects are to stay in their current treatment arm, or cross-over to the opposite arm. By including 220 participants (effectively 176 participants after 20% drop-outs) the study will achieve a power of \>95% to show non-inferiority of dupilumab to mepolizumab for both co-primary endpoints with the following criteria: Level of significance for both endpoints of a one-sided test, p\<0.025 and including previously found standard deviation (SD) values 1.9 for NPS and 22 for SNOT-22, an expected superior effect of 0.7 for NPS and 7 on SNOT-22, a minimal clinically relevant difference (MCID) of 1 for NPS and 12 for SNOT-22, respectively. Trial medication: All trial medication will be "off the shelf" i.e. no special labelling. It will be provided by hospital pharmacies in accordance with GMP. The investigational medicinal products (IMPs) are dupilumab (Dupixent, Sanofi) and mepolizumab (Nucala, GSK). Dupilumab are administered as subcutaneous injections of 300 mg every two weeks in the first 24 weeks. If the DMC response criteria (table 2) are met after 24 weeks, the dosing interval will be increased to every four weeks, in accordance with previous research and DMC recommendations. Mepolizumab is administered subcutaneously as 100 mg sc. every four weeks. Patients will continue standard of care treatment of INCS and saline irrigation, unless contraindicated. If rescue treatment is needed, a course of oral corticosteroids (Prednisolone) 37.5 mg once daily for 7 days will be given. Trial schedule: Planned first subject first visit May 2023 Planned last subject randomized February 2025 Planned last subject last visit:March 2026 End of trial March 2026