Ultrasound and Proteomics for Guselkumab Response Assessment in Crohn's Disease (UPGRADE).

The goal of this observational study is to evaluate the response of guselkumab in adult patients with Crohn's disease (CD) as measured on intestinal ultrasound (IUS), the relative quantities of CD64 in endoscopic tissue biopsies, and the protein signature in the blood of patients with and without therapy response. The main question it aims to answer is: * What is the proportion of ileal Crohn's disease patients with and without strictures who achieve an intestinal ultrasound response? * What is the quantity of CD64 in tissue in CD patients at baseline and at week 52 with and without IUS response? * Are there proteomic signatures in blood of CD patients that respond to GUS?