IL4 and chronic rhinosinusitis with nasal polyps: The efficacy of dupilumab, a monoclonal antibody anti IL-4 receptor alpha chain (IL-4Rα) blocking both IL-4 and IL-13 signalling, in difficult-to-treat and relapsing CRSwNP has been demonstrated in randomized clinical trials (RCTs), which showed a significant improvement in clinical outcomes after a few weeks of treatment [3].