Value of Pharmacokinetic Assays in the Prediction of Induction and Maintenance Therapeutic Response in Crohn's Disease

"During each 8 visits (screening, V0, V1, V2, V3, V4, V5, V6) at weeks-1, 0, 2, 6, 10, 14, 22, 54, respectively), the following parameters will be systematically recorded: Crohn's disease Activity Index (CDAI), adverse events.~Blood and fecal samples will be systematically collected at weeks 0, 2, 6, 10, 14, 22 and 54 for routine serum ultrasensitive CRP (C-Reactive Protein) and fecal calprotectin assessments and for vedolizumab pharmacokinetic parameters, including the vedolizumab trough levels and the specific anti-Vedolizumab antibodies. In case of loss of response, an additional measurement of serum CRP (C-Reactive Protein), fecal calprotectin and Vedolizumab pharmacologic parameters will be performed."