Upadacitinib (UPA), a selective JAK1 inhibitor, has shown robust efficacy in clinical trials for Crohn’s disease (CD) and ulcerative colitis (UC). However, real-world evidence in Asian populations remains limited. We aimed to evaluate the real-world effectiveness and safety of UPA in Korean patients with CD and UC across multiple centers.

We conducted a retrospective study across three Korean academic centers including adults with UC or CD treated with UPA. A total of 79 patients were analyzed (UC 30; CD 49). Clinical, biochemical, and endoscopic outcomes were assessed at week 16 for UC and week 12 for CD, and adverse events (AEs) were evaluated throughout follow-up.

 Among 79 patients, 88.6% (70/79) had prior exposure to at least one biologic therapy.  In UC (n=30), baseline disease activity was moderate to severe (median partial Mayo 8; endoscopic subscore 3). By week 16, substantial improvements were observed, with reductions in the partial Mayo score (to 2), endoscopic subscore (to 0), CRP, and fecal calprotectin (4034.8 → 185.5 μg/g). The UPA continuation rate was 96.7%, with discontinuation due to loss of response (n=1) or an adverse event (n=1). (Table 1)  In CD (n=49), baseline CDAI was high (mean 284.8), with a mean SES-CD of 10.4 and a median of two prior advanced therapies. By week 12, CDAI improved to 80.3, accompanied by reductions in CRP and fecal calprotectin (1408.6 → 458.4 μg/g). The UPA continuation rate was 83.6%, with discontinuation due to primary non-response (n=1), loss of response (n=5), or adverse events (n=2). (Table 2)  Across the entire cohort, the most frequent AEs were acne (49.4%), lymphopenia (11.4%), anemia (6.3%), herpes zoster (5.1%), and infections (6.3%); no thromboembolic events or malignancies occurred. (Table 3).

Upadacitinib demonstrated substantial clinical, biochemical, and endoscopic improvements in both UC and CD in this real-world Korean multicenter cohort. High continuation rates, particularly in UC, support its effectiveness even in biologic-experienced patients. The safety profile was consistent with clinical trials, with no thromboembolic events or malignancies observed. These findings support UPA as an effective and well-tolerated therapeutic option for refractory IBD in routine practice.support UPA as an effective and well-tolerated therapeutic option for refractory IBD in routine practice.