Real-world effectiveness and safety of budesonide MMX in Japanese patients with ulcerative colitis: A multicenter retrospective study

Introduction: Budesonide Multi-Matrix System (BUD-MMX) was approved in Japan in 2023 for active ulcerative colitis (UC); however, real-world data in Asian population are limited. We evaluated the real-world effectiveness and safety of BUD-MMX in Japanese patients with UC. Methods: We retrospectively reviewed patients with UC treated with BUD-MMX between September 2023 and August 2025 at six Japanese institutions. The primary outcome was clinical remission at week 8, defined as a partial Mayo score (PMS) ≤ 1 with a rectal bleeding subscore of 0. The secondary outcomes included week 4 remission, clinical response, safety, longitudinal changes in disease activity, and baseline clinical characteristics associated with week 8 remission. Results: Of 83 patients, 53 were included in the effectiveness analysis (median age, 52 years; 60.4% male; pancolitis, 49.1%; median baseline PMS, 4.0; prior advanced therapy [AT], 24.5%). Clinical remission was achieved in 37.7% and 59.2% of patients at weeks 4 and 8, respectively, and the clinical response reached 67.3% at week 8. PMS and Patient-Reported Outcome 2 (PRO2) declined significantly by week 4. The week-8 clinical remission rate was significantly higher in AT-naïve than in AT-exposed patients and in patients with low baseline PRO2 (1–2) than in those with moderate-to-severe PRO2 (3–6). In multivariable models adjusted for age and prior AT, baseline PRO2 and PMS were independently associated with remission. Adverse events occurred in 4.8% of patients, but all were mild. Conclusion: BUD-MMX was effective and well-tolerated in Japanese patients with mild-to-moderately active UC. Lower baseline PRO2 and PMS, and the absence of prior AT, predicted week-8 remission, supporting their use for patient selection.