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January 23, 2026

DOP030Real-world effectiveness and safety of mirikizumab in refractory, biologic-experienced ulcerative colitis patients

Key Points

The aim is to evaluate the effectiveness and safety of mirikizumab in refractory, biologic-experienced ulcerative colitis patients.
Prospective, observational, single-center study
Included UC patients treated with mirikizumab for at least 12 weeks
Clinical activity assessed using pMayo score at baseline, week 12, and 24
Collected demographic data, previous therapies, biomarkers, and adverse events
26.7% achieved clinical remission at week 12
45.0% showed clinical response at week 12
31.3% achieved clinical remission at week 24
19.2% experienced adverse events, mostly mild infections

Abstract

Abstract Background Mirikizumab is the first selective anti-IL-23p19 monoclonal antibody available for moderate to severe ulcerative colitis (UC). Real-world data remain limited, and available evidence mostly derives from registration trials. Early observational studies suggest encouraging short-term efficacy, but data in biologic-experienced, refractory populations are scarce. Methods We conducted a prospective, observational, single-center study including UC patients treated with mirikizumab with a minimum follow-up of 12 weeks. Demographic data and previous therapies were collected. Clinical activity was assessed using the pMayo score at baseline, at week 12 (W12), and at 6 months (W24). Biomarkers and endoscopic activity (eMayo) were recorded according to clinical practice. Adverse events and need for colectomy were documented. Clinical remission was defined as pMayo 2 without steroids and clinical response as a ≥ 3-point reduction without steroids. The primary endpoint was W12 clinical remission. Continuous variables were reported as medians (IQR) and categorical variables as counts and percentages. Fisher’s exact test was used for subgroup comparisons. Results A total of 120 patients treated with mirikizumab were included; all were biologic-experienced (median 3 prior biologics, IQR 2-4). The cohort was 55.8% male and 80.8% non-smokers; pancolitis was present in 49.2%. Bowel urgency at baseline was reported by 76.7%. Baseline endoscopy was available in 85 patients and showed moderate/severe activity in 87.1%. Median baseline CRP was 0.48 mg/dL (IQR 0.20-1.03) and fecal calprotectin 784 µg/g (IQR 367-1500). At W12, 26.7% (32/120) achieved clinical remission and 45.0% (54/120) showed clinical response. Among those with urgency at baseline, 68.5% (63/92) reported improvement or resolution. Of the 67 patients who had reached W24 at data collection, 31.3% (21/67) achieved clinical remission and 47.8% (32/67) showed clinical response. Six patients (5.0%) required colectomy. Adverse events occurred in 19.2% of patients, predominantly mild infections; no treatment-related serious adverse events were observed. Clinical remission rates were similar regardless of prior ustekinumab exposure (26.9% vs 26.5%), number of prior biologics (26.3% vs 26.7%), or prior anti-TNF therapy (22.2% vs 27.0%), with no significant differences. Interestingly, prior JAK inhibitor exposure was associated with significantly reduced W12 clinical remission (13.5% vs 32.5%, p = 0.043). Conclusion Mirikizumab is an effective and safe therapeutic option for biologic-experienced UC patients, showing short- and mid-term efficacy. The reduced response in JAK inhibitor-exposed patients highlights the potential importance of treatment sequencing in refractory disease. Conflict of interest: Melotti, Laura: No conflict of interest Dussias, Nikolas: Consultant fee from Cadigroup and Janssen Pardi, Veronica: No conflict of interest Gionchetti, Paolo: No conflict of interest Rizzello, Fernando: No conflict of interest

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