Mirikizumab Shows Progressive Histologic Improvement in Ulcerative Colitis, With Strong Rectal Response

Mirikizumab, an interleukin-23p19 inhibitor, demonstrated increasing histologic and histologic-endoscopic improvements over time in patients with moderately to severely active ulcerative colitis (UC), according to results from the phase 3b LUCENT-URGE study. The findings highlight continued efficacy beyond induction, particularly in rectal disease.

The open-label, single-arm study enrolled 172 adults with a baseline Modified Mayo Score of 4 to 9. Patients received intravenous mirikizumab induction at weeks 0, 4, and 8, followed by subcutaneous maintenance dosing through week 24. Histologic and endoscopic outcomes were assessed using standardized biopsy sampling from both the colon and rectum.

From week 12 to week 28, the proportion of patients achieving histologic-endoscopic mucosal improvement (HEMI) and remission (HEMR) increased across both anatomical sites. In the colon, HEMI rose from 26.7% to 38.4%, while HEMR increased from 23.3% to 32.6%. Improvements were more pronounced in the rectum, where HEMI increased from 22.7% to 35.5% and HEMR from 17.4% to 29.1%.

Histologic improvement and remission rates also increased numerically over time in both regions, suggesting ongoing anti-inflammatory effects with continued therapy.

The authors reported that “the proportions of patients achieving histologic and histologic-endoscopic endpoints increased from week 12 to week 28,” and noted “more notable improvement in the rectum.”

These findings reinforce the role of IL-23 inhibition in achieving deep remission and highlight the importance of evaluating both histologic and regional responses when assessing treatment effectiveness in UC.

Reference
Danese S, Magro F, Ponich T, et al. Mirikizumab provides positive histologic and endoscopic outcomes in patients with moderately to severely active ulcerative colitis.  Presented at: Digestive Disease Week; May 2–5, 2026; Chicago, Illinois.