Achieving Target Infliximab Drug Concentrations Improves Blood and Fecal Neutrophil Biomarkers in Crohn's Disease

Background: The neutrophil fecal biomarkers, calprotectin (FCP) and lactoferrin (LCT), and peripheral blood neutrophil CD64 surface receptor (nCD64) are biomarkers for mucosal inflammation in inflammatory bowel disease (IBD). Although FCP has been evaluated as a biomarker for mucosal healing, cut points for LCT and nCD64 are less known. We aimed to identify the cut points for LCT and nCD64 that were associated with FCP remission, with a secondary aim to evaluate the relationship between biochemical outcomes and infliximab (IFX) trough concentrations. Methods: We analyzed FCP, LCT, and nCD64 before and after IFX induction in a pediatric Crohn's disease (CD) cohort study. Week-14 FCP biomarker remission was defined as FCP 17.5 improvement. Predictive outcomes were calculated by receiver operating characteristics (ROCs). Results: Among 56 CD patients, ROC analysis identified an infusion 4 LCT 9.4 μg/mL (AUROC, 0.799, P = 0.002) and >11.5 μg/mL (AUROC, 0.835, P = 0.003) were associated with a FCP 5 μg/mL had a median FCP improvement (dose 1 to dose 4) of 90% compared with a median of 35% with levels