Induction Efficacy and Safety of Upadacitinib for Active Crohn's Disease in Japanese Patients: A Multicenter Retrospective Study.

Background: While Western real-world studies have demonstrated the therapeutic effect of upadacitinib in Crohn's disease (CD), data on Asian populations are scarce, and no real-world data from Japan have been reported. Therefore, this study aimed to assess the induction efficacy and safety of upadacitinib in Japanese patients with active CD. Methods: This retrospective study included CD patients who initiated upadacitinib at 10 inflammatory bowel disease (IBD) centers in Japan by December 2024. Clinical response, clinical remission, biomarker improvements, and adverse events were analyzed. Clinical response was defined as Crohn's Disease Activity Index (CDAI) < 150 or a decrease in CDAI (ΔCDAI) > 70, while clinical remission was defined as CDAI < 150. Results: A total of 33 patients (16 males, 17 females) were included. The median age at upadacitinib administration was 40 years, with a median disease duration of 9.3 years. The median baseline values were 264 for CDAI, 14 for Simple Endoscopic Score for Crohn's Disease (SES-CD), and 9.8 mg/L for serum C-reactive protein (CRP). Corticosteroids were co-administered in 11 patients (33.3%). Prior biologic therapy had been used in 25 patients (75.8%), including 7 patients with one biologic and 18 patients with two or more biologics. Extraintestinal manifestations were observed in 12 patients (36.4%), and perianal lesions in 15 patients (45.5%). All patients started upadacitinib at 45 mg/day. The clinical response, clinical remission, and steroid-free clinical remission rates were 76.7%, 53.3%, and 36.7% by week 4; 83.3%, 63.3%, and 56.7% by week 8; and 86.7%, 70%, and 70% by week 12, respectively. Significant improvements in CDAI, serum CRP, and albumin were observed at week 12 or the last visit, compared to baseline. Improvement was observed in 66.7% of cases with extraintestinal manifestations and 46.7% of cases with perianal lesions. Adverse events occurred in 45.5% of patients, with acne being the most common (12.1%). No serious adverse events leading to death were reported. The continuation rate of upadacitinib at week 12 or the last visit was 93.3%. Conclusion: Upadacitinib demonstrated high induction efficacy and acceptable safety in Japanese patients with active CD.