Short-Term Clinical and Biochemical Outcomes of IL-23p19 Inhibitors in Refractory Ulcerative Colitis: A Real-World Case Series

Introduction: IL-23p19 inhibitors have emerged as therapeutic options for moderate-to-severe ulcerative colitis (UC), but real-world data describing their early clinical use remain limited. Methods: We conducted a single-center retrospective study of consecutive adults with moderate-to-severe UC who initiated mirikizumab (n=10), risankizumab (n=15), or guselkumab (n=15) between January 2024 and March 2026. Clinical Activity Index (CAI), clinical response, clinical remission, leucine-rich alpha-2 glycoprotein (LRG), and adverse events were assessed over 12 weeks. Results: The cohort was predominantly treatment-refractory, with prior exposure to biologics or Janus kinase inhibitors in 67–100% of patients. Median CAI decreased from 5.5 to 3.5 with mirikizumab, from 8 to 3 with risankizumab, and from 7 to 3 with guselkumab by week 12. Week 12 clinical remission rates were 40%, 67%, and 67%, respectively. Median LRG levels decreased from 15.9 to 14.5 μg/mL, from 13.2 to 10.0 μg/mL, and from 14.4 to 11.1 μg/mL, respectively. Three patients discontinued therapy because of primary non-response: two treated with mirikizumab and one treated with risankizumab. No serious adverse events occurred. Conclusion: This 40-patient real-world cohort suggests short-term clinical and biochemical improvement after initiation of IL-23p19 inhibitors in refractory UC, with no serious adverse events observed during the 12-week observation period. These findings should be interpreted as preliminary and hypothesis-generating, and larger prospective studies are warranted to clarify long-term outcomes.