Study to Investigate the Efficacy and Safety of Dupilumab in Pediatric Patients With Active Eosinophilic Esophagitis (EoE)

The Primary objective is to demonstrate the efficacy of dupilumab treatment compared with placebo in pediatric patients with active eosinophilic esophagitis (EoE) based on histologic improvement meeting validated histologic criteria. The Secondary objectives are: * To demonstrate the efficacy of dupilumab compared to placebo in pediatric patients with active EoE after 16 weeks of treatment as assessed by endoscopic visual measurements of disease activity using the Eosinophilic Esophagitis-Endoscopic Reference Score (EoE-EREFS) and histologic abnormalities as measured by the EoE Histology Scoring System (EoE-HSS) * To evaluate the safety, tolerability, and immunogenicity of dupilumab treatment for up to 16 weeks in pediatric patients with active EoE * To evaluate the effects of dupilumab on transcriptomic signatures associated with EoE and type 2 inflammation * To study the effects of dupilumab on the type 2 inflammation gene expression signature * To evaluate the concentration-time profile of functional dupilumab in serum in this population * To assess efficacy of long-term (up to 160 weeks) dupilumab treatment * To assess the impact of dupilumab treatment on changes in weight and growth during the extended active period and open-label extension period of the study * To assess safety, tolerability, and immunogenicity of long-term (up to 160 weeks) dupilumab treatment * To evaluate the impact of dupilumab treatment on EoE signs and symptoms

This is a 3-part study: * Part A: Double-blind 16-week treatment period * Part B: 36-week extended active treatment period * Part C: Up to108 weeks open-label extension period