Efficacy and safety of filgotinib for ulcerative colitis: A real‐world multicenter retrospective study in Japan

Summary Background and Aims While filgotinib, an oral Janus kinase (JAK) 1 preferential inhibitor, is approved for moderately to severely active ulcerative colitis (UC), real‐world studies assessing its short‐ and long‐term efficacy and safety are limited. Methods This is a multicenter, retrospective study of UC patients who started filgotinib between March 2022 and September 2023. The primary outcome was clinical remission, defined as a partial Mayo score ≤1 with a rectal bleeding score of 0, or Simple Clinical Colitis Activity Index (SCCAI) ≤2 with a blood‐in‐stool score of 0. Secondary outcomes included clinical response, corticosteroid‐free remission, and endoscopic improvement. Outcomes were assessed at 10, 26, and 58 weeks based on patients with available follow‐up. Adverse events were evaluated. Results We identified 238 UC patients and 54% had prior exposure to biologics/JAK inhibitors. The median baseline partial Mayo score and SCCAI were 5 (IQR 3–6) and 4 (IQR 2–7). Clinical remission rates based on per‐protocol analysis at 10, 26, and 58 weeks were 47% (70/149), 55.8% (48/86), and 64.6% (31/48), respectively. At a median follow‐up of 28 weeks (IQR 10–54) with a discontinuation rate of 39%, the rates of clinical remission, clinical response, corticosteroid‐free remission, and endoscopic improvement were 39.9% (81/203), 54.7% (111/203), and 36.5% (74/203), and 43.5% (10/23), respectively. These rates were comparable between biologic/JAK inhibitor‐naïve and ‐experienced patients. While three patients (1.3%) developed herpes zoster infection, no cases of thrombosis or death were reported. Conclusions Real‐world data demonstrate favourable clinical and safety outcomes of filgotinib for UC.