P0959 - Colonic Tissue Expression of MAdCAM-1 Is Associated With Response to Vedolizumab in Patients With Inflammatory Bowel Disease

Nikhil Reddy, MD¹, Jeremy A. Klein, MD¹, Zifeng Deng, BS¹, Nikita Thomas, MSPH², Dejan Micic, MD¹, David T.. Rubin, MD, FACG³, Russell D.. Cohen, MD, FACG³, Sushila Dalal, MD³, Marc Bissonnette, MD³, Christopher Weber, MD, PhD¹, Joel Pekow, MD^3
1University of Chicago Medical Center, Chicago, IL; ²University of Chicago, Chicago, IL; ³University of Chicago Medicine, Inflammatory Bowel Disease Center, Chicago, IL

Introduction: Vedolizumab is an effective therapy for moderate-to-severe Crohn’s disease and ulcerative colitis. However, it is difficult to predict response to therapy. We aimed to characterize the predictive value of Mucosal Vascular Addressin Cell Adhesion Molecule 1 (MAdCAM-1) expression in patients with inflammatory bowel disease (IBD) at the University of Chicago.

Methods: We carried out a retrospective, single-center, cohort study with 109 prospectively enrolled adult patients. Patients had at least 3 IV vedolizumab doses and were maintained on vedolizumab. They also had pre-treatment inflammation based on fecal calprotectin (FCP) or colonoscopy within 12 months of initiation. Biopsies from the ileum or colon with the most severe histological inflammation were stained for MAdCAM-1 expression. Slides were uploaded to ImageScope and the tissue area of interest with the most severe inflammation was outlined. Relative expression of MAdCAM-1 staining was evaluated based on positive pixel count per area. T-tests were used to assess continuous variables. Clinical remission was defined as Harvey Bradshaw Index < 4 or Simple Clinical Colitis Activity Index < 2 at 14 weeks and was prospectively calculated. Endoscopic response was defined as a > 50% reduction of Simple Endoscopic Score in Crohn’s Disease or a Mayo Endoscopic Score decrease of 1 or more points.

Results: In pre-treatment biopsies of the entire cohort, there was no association with MAdCAM-1 expression and future clinical remission, nor with either improved endoscopic response or FCP < 200. However, among patients not already in clinical remission at baseline, lower MAdCAM-1 expression in weak, moderate and strong staining levels was associated with increased likelihood of clinical remission (p=0.044, 0.032, 0.006, Table 1). In addition, there were differences at all staining levels in post-treatment biopsies among patients who either had an endoscopic response or a FCP < 200 compared to those who did not (p=0.011, 0.007, 0.012, Table 1).

Discussion: We found that lower MAdCAM-1 expression after initiation of treatment with vedolizumab was associated with higher rates of endoscopic and biologic response. In patients with active clinical symptoms at baseline, tissue expression of MAdCAM-1 prior to treatment was associated with subsequent clinical remission but was not predictive of an endoscopic response. Future studies will be needed to further characterize the role of MAdCAM-1 in patients treated with vedolizumab.


Disclosures:


Nikhil Reddy, MD¹, Jeremy A. Klein, MD¹, Zifeng Deng, BS¹, Nikita Thomas, MSPH², Dejan Micic, MD¹, David T.. Rubin, MD, FACG³, Russell D.. Cohen, MD, FACG³, Sushila Dalal, MD³, Marc Bissonnette, MD³, Christopher Weber, MD, PhD¹, Joel Pekow, MD³. P0959 - Colonic Tissue Expression of MAdCAM-1 Is Associated With Response to Vedolizumab in Patients With Inflammatory Bowel Disease, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.