Therapeutic drug monitoring of infliximab and mucosal healing in inflammatory bowel disease: a prospective study

Data on the value of therapeutic drug monitoring of infliximab (IFX) to predict mucosal healing (MH) in inflammatory bowel diseases (IBD) are scarce. All consecutive patients with IBD receiving ongoing IFX (5 mg/kg) treatment and developing secondary failure to IFX were enrolled in a prospective study between June 2010 and May 2011. IFX trough levels, antibodies to IFX concentrations, C-reactive protein levels, and fecal calprotectin were measured before IFX optimization and at week 8. A proctosigmoidoscopy was performed on the day of first IFX optimization and at week 8 in all patients with ulcerative colitis (UC). MH was defined by fecal calprotectin 0.5 μg/mL was associated with MH (sensitivity [se], 0.88; specificity [sp], 0.77; P = 0.0001, area under the receiver operating characteristic curve, 0.89). On multivariate analysis, the only factor associated with MH after IFX optimization was a delta IFX >0.5 µg/mL (likelihood ratio = 2.02; 95% confidence interval, 1.01-4.08; P = 0.048) in patients with IBD. Therapeutic drug monitoring of IFX strongly predicts the likelihood of achieving MH following IFX dose intensification in both CD and UC.