A Study to Investigate the Efficacy and Safety of NSI-8226 in Adults With Eosinophilic Esophagitis

Key inclusion criteria Part A * Participant must be 18 to 75 years of age inclusive, at the time of signing the informed consent. * Established diagnosis of EoE with a previous EGD and esophageal biopsy confirming diagnosis of EoE. * Participants who have symptomatic EoE as defined by a history of on average at least 2 episodes of dysphagia per week in the 4 weeks prior to Screening. * Must remain on a stabilized diet for at least 8 weeks prior to Visit 1 and during the course of the study. * May be on any background PPI and/or STC, during the course of the study, as long as background medications have been stable for at least 8 weeks prior to the Screening and must agree to no changes to background medication or dosage unless medically indicated. * Discontinuation of any marketed investigational drug or biologic (monoclonal or polyclonal antibody) within 30 days or 5 half-lives prior to screening, whichever is longer. * Participants should have previously documented standard of care treatment, which could include PPI and/or STC and/or diet. Key exclusion criteria Part A * Female participant who is pregnant or breastfeeding. * Have a history or presence of any other gastrointestinal disorders such as active Helicobacter pylori infection, history of achalasia, hyper eosinophilic syndrome and eosinophilic granulomatosis with polyangiitis, esophageal varices, Crohn's disease, ulcerative colitis, inflammatory bowel disease, celiac disease, eosinophilic enteritis, gastritis, …