Maarten Cozijnsen

Abstract Objective Adalimumab, a humanized anti-tumor necrosis factor antibody, is an effective treatment in adult patients with refractory Crohn’s disease (CD). The available literature on its efficacy in children remains limited. We aimed to evaluated its real-world efficacy in pediatric CD patients and to compare its efficacy between infliximab non-responders and patients who lost response to infliximab. Methods All Dutch CD patients receiving adalimumab before the age of 18 after previous infliximab therapy, were identified. We analyzed longitudinal disease activity, assessed by the mathematically weighted pediatric Crohn’s disease activity index (wPCDAI) or the Physician Global Assessment (PGA), and adverse events. Results Fifty-three CD patients were included. Twelve patients received monotherapy and the others received combination treatment with thiopurines (n=21), methotrexate (n=11), steroids (n=7) or exclusive enteral nutrition (n=2). Median follow-up was 12 months (IQR 5-23). Remission was reached in 34 patients (64%, wPCDAI<12.5 or PGA=0) after a median of 3.3 months, and maintained by 50% for 2 years. Eleven patients (21%) reached response but not remission (decrease in wPCDAI≥17.5 or decrease in PGA). Eighteen patients (34%) failed adalimumab treatment because of non-response (n=4), lost response (n=11) or adverse events (n=3). More infliximab non-responders failed adalimumab treatment than patients who lost response to infliximab (2/3 vs 8/34, HR 18.8, CI 1.1-303.6). Only one patient encountered a serious adverse event, a severe but nonfatal infection. Conclusions In clinical practice, adalimumab induces remission in two-thirds of children with infliximab refractory CD.