Mirikizumab induction, prolonged if needed, achieves 68% steroid-free remission in refractory Ulcerative Colitis

Ulcerative Colitis (UC) is a chronic inflammatory bowel disease characterized by debilitating symptoms like urgency and bloody stools. Current advanced therapies often fall short, especially in patients with prior treatment failures, leading to a significant unmet need for effective and durable remission strategies. Mirikizumab is an IgG4 monoclonal antibody that selectively targets the IL-23 p19 subunit, a key cytokine involved in chronic inflammation. While pivotal trials have demonstrated its efficacy, real-world data are crucial to understand its performance in diverse, often more challenging, patient populations.

This prospective, real-world study enrolled 105 UC patients from 12 centers in the Sicilian Network for Inflammatory Bowel Disease (SN-IBD). All patients initially received 3 monthly intravenous infusions of 300 mg Mirikizumab. In cases of inadequate response, the induction period was prolonged with additional doses. Primary endpoints included clinical response, steroid-free remission (SFR), and reduction of urgency (measured by Urgency Numerical Rating Scale - UNRS) at week 12 and week 24. Secondary endpoints assessed the need for prolonged induction and safety.

The study cohort was highly refractory, with 74% of patients having failed 2 or more previous lines of advanced therapies. At week 12, 24% of patients achieved a clinical response, and 53% achieved SFR. The median urgency score significantly decreased from 6 at baseline to 2 at week 12 (p < 0.001). For the 71 patients followed to week 24, the clinical response rate was 20%, while SFR increased to 68%. The median urgency score further dropped to 1 at week 24 (p < 0.001).