263. DUPILUMAB EFFICACY AND SAFETY TO 52 WEEKS IN ADULT AND ADOLESCENT PATIENTS WITH EOSINOPHILIC ESOPHAGITIS: RESULTS FROM LIBERTY EOE TREET

Abstract Background In Parts A and B of the 3-part, phase 3 LIBERTY EoE TREET study (NCT03633617), dupilumab 300 mg weekly (DPL qw) vs placebo (PBO) demonstrated significant efficacy and acceptable safety up to 24 weeks in adults and adolescents with eosinophilic esophagitis (EoE). Patients who completed Parts A and B entered Part C and received DPL qw to 52 weeks. Here we present 52-week results from patients who completed Part B and continued to Part C. Methods Of 80 DPL qw patients in Part B, 74 continued DPL qw in Part C (DPL/DPL). Of 79 PBO pts in Part B, 37 patients received DPL qw in Part C (PBO/DPL). Part B co-primary endpoints were proportion of patients achieving peak esophageal intraepithelial eosinophil (eos) count ≤6 eos/high- power field (hpf) and absolute change from Part B baseline in Dysphagia Symptom Score (DSQ) score at Week 24. Key secondary endpoints are listed in the Table. In Part C, all co-primary and secondary endpoints were assessed at Week 52 as secondary endpoints. Safety was also assessed. Results At Week 52, 84.6% of DPL/DPL and 67.6% of PBO/DPL patients achieved peak eos count ≤6 eos/hpf; mean (SD) absolute change from Part B baseline in DSQ score was −30.26 (15.39) for DPL/DPL and − 27.25 (11.46) for PBO/DPL patients. At Week 52, 100% of DPL/DPL and 78.4% of PBO/DPL patients achieved peak eos count <15 eos/hpf, 30.8% of DPL/DPL and 16.2% of PBO/DPL patients achieved peak eos count ≤1 eos/hpf, and compared to Part B baseline, peak eos count, EREFS, and HSS grade and stage scores were reduced (Table). DPL demonstrated an acceptable safety profile. Conclusion DPL qw demonstrated persistent improvements in clinical, symptomatic, histologic, and endoscopic features of EoE up to 52 weeks and had an acceptable safety profile. PBO patients from Part B who received DPL in Part C showed similar efficacy to dupilumab qw patients of Part B.