Colonic Tissue Expression of <scp>MAdCAM</scp> ‐1 Is Not Predictive of Vedolizumab Responsiveness in Inflammatory Bowel Disease

We assessed the predictive value of MAdCAM-1 expression on response to vedolizumab in patients with inflammatory bowel disease. This was a retrospective, single-center, cohort study including 109 patients with pretreatment inflammation who completed at least three doses of vedolizumab. We described clinical and endoscopic outcomes of patients based on MAdCAM-1 expression. There was no significant difference in MAdCAM-1 expression when stratified by histology. Patients in clinical remission at 14 weeks had significantly lower median baseline MAdCAM-1 expression (37425.3 vs. 46278.9, p < 0.015). There was no difference in pretreatment MAdCAM-1 expression among patients who later achieved endoscopic or biologic response. In the posttreatment cohort, lower MAdCAM-1 expression was associated with an increased likelihood of endoscopic or biologic response (36719.5 vs. 44229.9, p < 0.038). However, posttreatment MAdCAM-1 expression did not significantly differ when stratified for clinical remission at 14 weeks. Ultimately, MAdCAM-1 immunohistochemistry has limited utility as a predictive biomarker but may provide insights into vedolizumab-associated bowel healing.