Mirikizumab in ulcerative colitis: real-world evidence from an international two-center retrospective cohort study.

Background: Mirikizumab is a first-in-class IL-23p19 inhibitor, which is approved for the treatment of adults with moderate to severe ulcerative colitis (UC). Objectives: We aimed to assess the effectiveness and safety of mirikizumab in moderate to severe UC in a real-world cohort from two inflammatory bowel disease referral centers. Design: This was a two-center international retrospective observational cohort study. Methods: This study aimed to assess the effectiveness and safety of mirikizumab for 12 weeks of induction. Clinical response and remission were defined as a reduction in the Simple Clinical Colitis Activity Index (SCCAI) of ⩾3 points, and SCCAI ⩽ 2, respectively. The primary outcome was the clinical remission rates after 12 weeks of induction. Results: We included 74 adult patients (58.1% female, 56.8% pan-colitis extent). Most patients (69/74, 93%) were previously exposed to a biological or a small-molecule therapy, and 39 (52.7%) started mirikizumab while on corticosteroids. By the end of induction, 8.1% discontinued therapy due to either lack of efficacy or an adverse event. Overall, clinical response, clinical remission, and corticosteroid-free-remission were 70.3%, 17.6%, and 16%, respectively. Week-12 clinical response and clinical remission rates were comparable between exposed and naïve patients for anti-tumor necrosis factor agents, ustekinumab, vedolizumab, and Janus-kinase inhibitors. Conclusion: Mirikizumab was effective for inducing clinical response and well-tolerated in a substantial cohort of treatment-experienced patients with UC. This positions mirikizumab as a valuable option to the expanding therapeutic armamentarium for UC.