S1768 Early Response of Mirikizumab Therapy for Ulcerative Colitis Patients in a Real-World Setting

Introduction: Ulcerative colitis (UC) is a debilitating condition with high morbidity and mortality. Despite many available advanced therapies, there is a patient subset with persistent, moderate-severely active UC. Mirikizumab (MIRI) is an IL23 inhibitor recently approved for UC patients with moderate-severe disease. The LUCENT-1 induction trial assessed MIRI efficacy for patients with 0 to 2 therapy failures. This study looks at MIRI induction in a real-world cohort. Methods: This retrospective, single-center study included UC patients who received MIRI (2023 – 2024). Baseline characteristics were assessed to determine response predictors. Variables included demographics, disease severity, blood and stool biomarkers, location (Montreal classification), and historic therapies. Clinical parameters were Mayo score and Simple Clinical Colitis Activity Index (SSCAI). Exclusion criteria included lack of MIRI initiation/follow-up and LUCENT inclusion. Results: Of 25 initial patients prescribed MIRI, 16 were analyzed; exclusion was due to lack of initiation (5)/follow-up (3) or LUCENT inclusion (1). Fifty percent were women, 88% White, and 13% Hispanic. Twelve patients (75%) had pancolitis and an average of 3 prior advanced therapies. Fifteen (94%) failed a TNF-α inhibitor, and 44% failed IL12/IL23 (ustekinumab). Twelve patients (75%) had symptomatic improvement (partial Mayo) during induction. They had higher baseline partial Mayo/SSCAI, a greater reduction in the same, and more reduction of fecal calprotectin. These 12 were on therapy longer (3 vs 1.5 months). Intestinal ultrasound (IUS) had complete transmural healing (2 patients). Interval colonoscopy at 2 months (2 patients) did not yet reveal endoscopic improvement, however, both had symptomatic improvement. One patient discontinued MIRI – she had persistent inflammation per IUS and colonoscopy 6 months into therapy. Conclusion: This retrospective study of MIRI induction noted symptomatic improvement based on clinical scores and biomarker improvement. The patient subset without improvement was on therapy for a shorter period of time, likely contributing to limited response. In the patient subgroup who underwent further evaluation, IUS demonstrated transmural healing, while colonoscopy had not yet demonstrated improvement. We suspect short time on therapy limited endoscopic evaluation. All but one patient continued MIRI post-induction. In this study, MIRI improved symptoms and inflammatory markers in the majority of patients.