This is parallel, Phase 4 study which consists of a 24 week (0.5 years) randomized, double blind, placebo controlled, 2-arm treatment period followed by an open label segment of 104 weeks (2 years) for a total of 128 weeks (2.5 years) to evaluate the effect of dupilumab treatment on esophageal function, and remodeling in adults with eosinophilic esophagitis.

Duration of study period (per participant)

• Screening period: Up to 12 weeks before Week 0
• Randomized double-blind period: 24 weeks
• Open label period: 104 weeks
• Post Investigational Medicinal Product (IMP) intervention follow-up period: up to 12 weeks or until the participants switch to commercialized dupilumab, whatever comes first.

There will be ten (10) site visits, and five (5) direct-to-participant IMP delivery visits (except if prohibited by local regulatory authorities or if participant is not willing. In this case, IMP will be dispensed at the study site).

The duration per participant will be up to 152 weeks.

Inclusion Criteria:

• A documented diagnosis of EoE by endoscopic biopsy.
• Baseline endoscopic biopsies with a demonstration on central reading of intraepithelial eosinophilic infiltration.
• History (by participant report) of an average of at least 2 episodes of dysphagia (with intake of solids) per week in the 4 weeks prior to screening.
• Body weight ≥40 kg.

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

• Other causes of esophageal eosinophilia or the following conditions: hypereosinophilic syndrome or eosinophilic granulomatosis with polyangiitis (Churg Strauss syndrome).
• Active Helicobacter pylori infection.
• History of achalasia, Crohn's disease, ulcerative colitis, celiac disease, and prior esophageal surgery.
• Any esophageal stricture unable to be passed with a standard, diagnostic, 9 to10 mm upper endoscope or any critical esophageal stricture that requires dilation at screening.
• History of bleeding disorders or esophageal varices.
• Treatment with swallowed topical corticosteroids within 8 weeks prior to baseline.
• Initiation or change of a food elimination diet regimen or reintroduction of a previously eliminated food group in the 6 weeks prior to screening.
• Participation in prior dupilumab clinical study or participants currently treated or have been treated with commercially available dupilumab or contraindicated to dupilumab per local labelling.

The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org