Upadacitinib in Colonic Crohn’s Disease: A Narrative Review of Mechanistic Rationale, Clinical Trial Evidence, and Real-World Outcomes

Abstract

Crohn’s disease (CD) is a chronic inflammatory bowel disorder with colonic involvement in a substantial proportion of patients, often associated with increased symptom burden and therapeutic complexity. Upadacitinib, a selective Janus kinase 1 (JAK1) inhibitor, has emerged as an effective oral therapy for moderate-to-severe CD, including patients with colonic-predominant disease. This narrative review synthesizes evidence from phase 2 and 3 randomized controlled trials, post-hoc subgroup analyses, long-term extension studies, and real-world observational cohorts evaluating the efficacy and safety of upadacitinib in CD with colonic involvement. Across pivotal trials, induction therapy demonstrated superior rates of clinical remission (approximately 39-50% versus 21-29% with placebo), significant endoscopic response, and rapid symptom improvement. Maintenance therapy sustained both clinical and endoscopic outcomes through one year and beyond. Real-world studies corroborate effectiveness in highly treatment-experienced populations, although heterogeneity in study design limits causal inference. The safety profile is consistent with known JAK inhibitor class effects, with infections—particularly herpes zoster—requiring appropriate risk mitigation. Pharmacogenetic predictors of response to upadacitinib remain undefined, representing an important area for future research. Overall, upadacitinib constitutes a valuable therapeutic option for patients with refractory colonic CD, while comparative effectiveness and precision-medicine strategies warrant further investigation.