A Proof-of-Concept Study to Assess the Efficacy, Safety and Tolerability of Itepekimab (Anti--IL-33 mAb) in Participants With Chronic Rhinosinusitis Without Nasal Polyps

ACT18421 is a multinational, randomized, double-blind, placebo-controlled, parallel-group, Phase 2 study with 3 treatment groups. The purpose of the study is to evaluate the efficacy, safety and tolerability of 2 dosing regimens of itepekimab compared to placebo in male and female participants with chronic rhinosinusitis without nasal polyps (CRSsNP) aged 18 years of age and older. Study details include: * The study duration (4-week screening, 24--week intervention, 20--week safety followup) will be 48 weeks. * The intervention duration will be 24 weeks. * The number of visits will be 7 site visits and 8 phone/remote visits.