An Extension Study to Investigate the Long-term Safety and Tolerability of Itepekimab in Adult Participants With Inadequately Controlled Chronic Rhinosinusitis With Nasal Polyps

This is a double-blind, parallel-group, Phase 3, 2-arm study that is designed to provide additional safety information, assess the durability of treatment response, and provide additional PK and immunogenicity assessments. The primary purpose of this study is to evaluate safety and tolerability of both new or continued treatment with itepekimab 300 mg SC high dose or itepekimab 300 mg SC low dose in participants with CRSwNP having completed the intervention period of the clinical studies EFC18418 or EFC18419. A secondary purpose of this study is to provide efficacy outcomes beyond the intervention period of the parent trials EFC18418 and EFC18419. Study details include: * The study duration will be up to 72 weeks. * The intervention duration will be 52 weeks. * A follow-up period of 20 weeks will be conducted. * The number of visits will be 8 and the number of phone contacts will be 4.

Inclusion Criteria: * Participants with CRSwNP who completed the 52-weeks intervention period in a previous itepekimab CRSwNP Phase 3 clinical study (ie, EFC18418 or EFC18419) and for which an EOT visit occurred no later than 5 days before the enrollment visit of this study. * A female participant is eligible to participate if she is not pregnant or breastfeeding, and at least one of the following conditions applies: * Is not a women of childbearing potential (WOCBP), OR * Is a WOCBP who agrees to follow the contraceptive guidance during the intervention period and for at least 20 weeks after the last dose of study intervention. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * Diagnosis of a malignancy during parent study, except a squamous or basal cell carcinoma of the skin. * Any opportunistic infection during the parent study, such as tuberculosis (TB) or other infections whose nature or course may suggest an immunocompromised status. * Anaphylactic reactions or systemic allergic reactions that are related to IMP and require treatment during the parent study. * Any other situation that led to a permanent premature IMP discontinuation in parent trials. The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.