Relationship between Serum Adalimumab Levels and Clinical Outcome in the Treatment of Inflammatory Bowel Disease

Abstract

Background: Adalimumab (ADA) is an anti-tumor necrosis factor agent that has been shown to be effective in inducing and maintaining remission in adult patients with inflammatory bowel disease. The relationship between the ADA trough levels and clinical efficacy has been demonstrated, but there is variability in the definition of the most suitable range for its clinical applicability. Summary: A review of published studies during the last 5 years on ADA serum levels and its relationship with the clinical outcome was performed. The studies selected included 7 observational studies, a systematic review, a meta-analysis and a post hoc analysis of a clinical trial. The reported ADA levels that discriminate patients in clinical remission from those with active disease range from 4.5 to 8 µg/mL. This therapeutic range varies when considering endoscopic remission (7.5 to >13.9 µg/mL). Although the sample of patients with ulcerative colitis is small, a tendency to reach higher levels of ADA is observed in both clinical and endoscopic remission. Key Messages: The optimal therapeutic cut-off point of serum ADA levels ranges from 4.5–5 to 12 µg/mL, where ADA levels are associated with an adequate clinical monitoring of the disease during maintenance therapy. These ranges vary according to the target, suggesting levels of 4.8 µg/mL as the cut-off for clinical remission and levels ≥7.5 µg/mL for mucosal healing/endoscopic response. Controlled prospective studies are required to determine the optimal therapeutic interval of ADA serum levels both as induction and as maintenance therapy.