S981 Long-Term Dupilumab Therapy Maintains Improvements in Esophageal Features of Eosinophilic Esophagitis (EoE) as Measured by Endoscopic Reference Score in Children With EoE: 100-Week Results From EoE KIDS

Introduction: Eosinophilic esophagitis (EoE) is a chronic, progressive, type 2 inflammatory disease of the esophagus. Endoscopic Reference Score (EREFS) evaluates severity of endoscopic EoE features (edema, rings, exudates, furrows, and strictures), with subscores for inflammation and fibrostenosis. Dupilumab is approved for EoE in the U.S. and E.U. in patients aged ≥1 year, weighing ≥15 kg. Dupilumab significantly improved worst observed region (WOR) EREFS scores in children aged 1-11 years with active EoE in Parts A and B of the phase 3 EoE KIDS study (NCT04394351). This post hoc analysis assessed long-term dupilumab’s effect on WOR EREFS scores to week 100 in EoE KIDS. Methods: This analysis includes patients who received higher-exposure (HE) dupilumab or placebo (PBO) during the 16-week double-blind phase (Part A), and HE dupilumab during the 36-week extension (Part B). Patients who completed Part B were eligible for Part C, where they received the same weight-tiered, open-label dupilumab regimen. EREFS scoring was based on WOR (range 0-9), derived using the highest score for each feature from proximal/distal esophageal regions. Results: Thirty-three of 61 patients enrolled in Part C were included. At Part A baseline, mean (95% confidence interval [CI]) EREFS total scores for PBO/dupilumab and dupilumab/dupilumab groups were 4.27 (3.34, 5.19) and 4.03 (3.44, 4.62), respectively, and proportions of patients (95% CI) who achieved EREFS total scores of ≤2 and 0 were 13.3% (1.7%, 40.5%) and 17.6% (6.8%, 34.5%), and 0.0% (0.0%, 21.8%) and 2.9% (0.1%, 15.3%), respectively. At week 100, mean (95% CI) change in EREFS total score was maintained from week 52 (-3.27 [-4.14, -2.39] vs -2.56 [-3.21, -1.91], respectively). Mean (95% CI) changes at week 100 were maintained from week 52 in EREFS inflammation subscore (-2.87 [-3.56, -2.18] vs -2.28 [-2.81, -1.75]) and fibrostenotic subscore (-0.40 [-0.68, -0.12] vs -0.28 [-0.53, -0.03]). Greater proportions of patients (95% CI) achieved endoscopic improvement (EREFS total score ≤2) and endoscopic normalization (EREFS total score 0) at week 100 relative to week 52 (100.0% [81.5%, 100.0%] vs 83.9% [66.3%, 94.6%] and 38.9% [17.3%, 64.3%] vs 25.8% [11.9%, 44.6%], respectively). Conclusion: Long-term dupilumab maintained improvements in EREFS total score, and inflammation and fibrostenotic subscores at week 100 relative to week 52 in pediatric patients with EoE. Further improvements were also observed in proportions of patients achieving endoscopic improvement and normalization.