Steenholdt, Casper3; Al-Khalaf, Magid3; Brynskov, Jørn3; Bendtzen, Klaus3; Thomsen, Ole Ø3; Ainsworth, Mark A5
1 Section of Orthopaedics and Internal Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet2 Section of Surgery and Internal Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet3 unknown4 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet5 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
BACKGROUND: The aim of the study was to investigate variations in anti-infliximab (IFX) antibody (Ab) levels and clinical implications thereof in patients with inflammatory bowel disease (IBD). METHODS: A retrospective, explorative, single-center study of patients with IBD who developed anti-IFX Ab and in whom anti-IFX Ab were reassessed. RESULTS: IFX was administered to 316 patients; anti-IFX Ab was determined in 180 patients and detected in 83 (46%). During ongoing IFX maintenance therapy, anti-IFX Ab disappeared at later reassessment in two-thirds of patients with clinical response after median 4 (3-5) infusions. In contrast, anti-IFX Ab persisted in all patients without clinical response. Anti-IFX Ab appeared pharmacologically active, as IFX levels were high when anti-IFX Ab disappeared (median 3.7 µg/mL, interquartile range [IQR] 2.8-5.5), while undetectable or low when anti-IFX Ab persisted (median 0 µg/mL, IQR 0-0). In 56 patients, anti-IFX Ab were assessed after IFX discontinuation. The proportion of patients with anti-IFX Ab gradually declined over time, with a few patients having anti-IFX Ab up to about 4 years after initial assessment. No variables were associated with anti-IFX Ab disappearance in multivariate analysis. CONCLUSIONS: Discontinuation of IFX is advisable in patients with inadequate response and repeat positive anti-IFX Ab measurements. Anti-IFX Ab can persist for years after discontinuation, which could impact efficacy and safety at retreatment. Continued IFX treatment may, however, be considered in patients with clinical response and a single positive anti-IFX Ab measurement, as anti-IFX Ab disappears in two-thirds of these during continued treatment. (Inflamm Bowel Dis 2012;).