A Phase 2 Study of Tofacitinib, an Oral Janus Kinase Inhibitor, in Patients With Crohn’s Disease

Background & Aims Tofacitinib, an orally administered Janus kinase inhibitor, blocks signaling through γ-chain–containing cytokines (interleukins 2, 4, 7, 9, 15, and 21). We performed a phase 2 trial to measure its efficacy in patients with moderate-to-severe active Crohn’s disease. Methods Patients (N = 139; age, ≥18 y) with moderate-to-severe active Crohn’s disease were assigned randomly to groups given 1 mg (n = 36), 5 mg (n = 34), or 15 mg (n = 35) tofacitinib or placebo (n = 34), twice daily for 4 weeks, at 48 centers in 12 countries. The primary end point was the proportion of clinical responders at week 4 (decrease from baseline in the Crohn’s Disease Activity Index score of ≥70 points [Response-70]). Secondary end points included clinical remission (Crohn’s Disease Activity Index score of