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Although eosinophils are the hallmark of eosinophilic esophagitis (EoE) with threshold levels required for diagnosis, their exact role in EoE is unclear. The EoE-Endoscopic Reference Score (EREFS) assesses endoscopic inflammatory (edema/exudate/furrows) and remodeling (rings/strictures) features. We assessed the correlations between peak esophageal intraepithelial eosinophil count (eos/high-power field [hpf]) and EREFS in placebo-treated EoE patients from two clinical trials: phase 2 proof-of-concept (POC; NCT02379052; n = 24) and part A of phase 3 TREET (Phase3-PartA; NCT03633617; n = 39). POC was a 12-week trial in adults and Phase3-PartA was a 24-week trial in adults and adolescents. Endoscopic examination of the esophagus was performed at baseline (BL) and end of treatment (EOT) and scored for inflammatory and remodeling subscores and total score using EREFS (higher scores indicate greater severity). Peak eos/hpf was measured from pinch biopsies of proximal, mid, and distal esophagus at BL and EOT. Pearson correlations were performed between total/proximal/mid/distal eos/hpf and EREFS total, subscores, and components at BL, EOT, and for change from BL at EOT. Some strong correlations (r > 0.5) were observed between total peak eos/hpf and EREFS at BL in both studies and at EOT in Phase3-Part A (Table). Moderate-to-strong correlations (r > 0.3) were observed between total peak eos/hpf and EREFS inflammation subscore and edema/exudates/furrows individual components (some P > 0.5) in both studies. Correlations of total peak eos/hpf with EREFS remodeling subscore and rings/stricture components were not significant (P = 0.07–0.94). Peak eos/hpf in the proximal, mid, or distal esophagus were more strongly associated with EREFS inflammation subscore (majority moderate-to-strong correlations; P = 0.001–0.66) than EREFS remodeling subscore (weak correlations, P = 0.22–0.99) at BL/EOT for both studies. In these EoE patients, moderate-to-strong correlations were observed between eos/hpf and endoscopic markers of inflammation. No strong correlations were observed between total, proximal, mid, or distal peak eos/hpf and endoscopic parameters of remodeling. These data support a role for intact eosinophils in inflammatory changes in the esophagus in EoE and demonstrate the need for both histology and endoscopic evaluation. Further study, with larger sample sizes, is required to verify these findings in other contexts.

The Histologic Scoring System (HSS) assesses severity/extent of histologic features (eosinophil density [ED]/basal zone hyperplasia [BZH]/eosinophil abscesses [EA]/eosinophil surface layering [SL]/surface epithelial alteration [SEA]/dyskeratotic epithelial cells [DEC]/dilated intercellular spaces [DIS]/lamina propria fibrosis [LPF]) in eosinophilic esophagitis (EoE). The Endoscopic Reference Score (EREFS) assesses endoscopic feature severity (edema/exudates/furrows/rings/strictures). We correlated HSS components with inflammatory/remodeling EREFS components in placebo-treated EoE patients from 2 trials—phase 2 proof-of-concept (POC; NCT02379052), phase 3 TREET part A (Phase3-PartA; NCT03633617). POC was a 12-week trial in adults, and Phase3-PartA was a 24-week trial in adults and adolescents. Proximal/mid/distal esophagus biopsies were collected at baseline/end of treatment (EOT) and scored by HSS for grade (severity)/stage (extent)/components (higher scores = greater severity). Endoscopies were scored by EREFS (higher scores = greater severity) and inflammatory (edema+exudates+furrows) and remodeling (rings+stricture) subscores calculated. Pearson correlation and single co-variate regression model analyses were performed between baseline HSS grade/stage, total/individual components scores and EREFS total/components scores and subscores, and for the change in scores from baseline at EOT (ΔEOT). Moderate-to-strong correlations (r > 0.3) were observed between total EREFS and HSS grade/stage for baseline/ΔEOT in POC and baseline in Phase3-PartA (Table). Moderate correlations were observed between BZH and EREFS remodeling subscore and rings for ΔEOT in Phase3-PartA; DIS grade and EREFS remodeling subscore and strictures for baseline and ΔEOT in POC but not Phase3-PartA; and EREFS inflammation and remodeling subscores and components for SEA and SL at baseline and ΔEOT in POC. Moderate-to-strong correlations were observed between EREFS inflammation subscore and DIS stage and between edema and DIS grade/stage at baseline in both studies. Similar results were observed using regression analyses. Specific components of HSS and EREFS, reflecting inflammatory and remodeling processes, are closely correlated, when examined by Pearson correlations or regression analyses, and can aid identification of fibrostenotic or inflammatory phenotypes in EoE. Correlations of DIS with endoscopic inflammatory and remodeling features reflect the role of barrier dysfunction in maintaining chronic inflammation that ultimately leads to remodeling.