Biological treatments have revolutionized the treatment of inflammatory bowel diseases (IBD; Crohn’s disease (CD) and ulcerative colitis (UC)),1, –3 with the potential to achieve mucosal healing or transmural healing based on the treat-to-target approach proposed by STRIDE-II consensus.4 Specifically, vedolizumab (VDZ) is a humanized IgG1 monoclonal antibody that targets α4β7 integrin and inhibits the interaction with mucosal addressin cell adhesion molecule-1, resulting in the prevention of leukocyte extravasation to the inflamed tissue. The gene discussed is MADCAM1; the disease is inflammatory bowel disease.