Rationale for an Eosinophilic Esophagitis Treat-to-Target Concept

Eosinophilic esophagitis (EoE) is a chronic T helper 2-mediated inflammatory disorder of the esophagus defined clinically by the presence of symptoms of esophageal dysfunction and histologically by an eosinophil-predominant infiltration. Correspondingly, treatment has aimed at controlling both symptom severity and histologic activity. However, with emerging clinical and pathophysiologic understanding of the disease, it has become increasingly apparent that other disease aspects need to be targeted as well, such as endoscopic severity and quality of life. Moreover, with the role of eosinophils having been questioned lately, histologic changes beyond eosinophil infiltration have come to attention and are captured by newly validated scores. In addition, EoE is being increasingly considered a transmural disease that cannot be assessed by simple endoscopy but needs measurement of esophageal distensibility, a surrogate marker for fibrosis. Finally, novel tools such as measurement of esophageal impedance could make it possible to assess for complete restoration of the esophageal epithelium, potentially corresponding to disease clearance. This article reviews the various outcome parameters in adult EoE management and proposes an algorithm for a treat-to-target concept, in analogy to what has been practiced in inflammatory bowel disease treatment for the last 10 years.