Targeting the α4β7-MAdCAM-1 axis with vedolizumab (VDZ) is a front-line therapeutic paradigm in ulcerative colitis (UC). However, mechanism(s) of action (MOA) of VDZ remain relatively undefined. Here, we examined three distinct cohorts of patients with UC (n=83, n=60, and n=21), to determine the effect of VDZ on the mucosal and peripheral immune system. Transcriptomic studies with protein level validation were used to study drug MOA using conventional and transgenic murine models. We found a significant decrease in colonic and ileal naive B and T cells and circulating gut-homing plasmablasts (β7+) in VDZ-treated patients, pointing to gut-associated lymphoid tissue (GALT) targeting by VDZ. Murine Peyer's patches (PP) demonstrated a significant loss cellularity associated with reduction in follicular B cells, including a unique population of epithelium-associated B cells, following anti-α4β7 antibody (mAb) administration. Photoconvertible (KikGR) mice unequivocally demonstrated impaired cellular entry into PPs in anti-α4β7 mAb treated mice. In VDZ-treated, but not anti-tumor necrosis factor-treated UC patients, lymphoid aggregate size was significantly reduced in treatment responders compared to non-responders, with an independent validation cohort further confirming these data. GALT targeting represents a novel MOA of α4β7-targeted therapies, with major implications for this therapeutic paradigm in UC, and for the development of new therapeutic strategies.
Vedolizumab is used as a treatment for patients with inflammatory bowel disease (IBD), but induction therapy leads to clinical response and remission in approximately 55% and 30% of patients with IBD, respectively. In this study, we aimed to explore the predictive value of mucosal eosinophils and serum eotaxin-1 regarding response to vedolizumab induction therapy. Eighty-four (84) patients with IBD (37 Crohn’s disease [CD], 47 ulcerative colitis [UC]) were included. For 24 patients with IBD, histopathology was assessed for eosinophil counts in non-inflamed colonic tissue prior to vedolizumab treatment. For 64 patients with IBD, serum eotaxin-1 levels were quantified prior to (baseline) and during vedolizumab treatment. Serum samples of 100 patients with IBD (34 CD, 66 UC) from the GEMINI 1 and 2 trials were used for external validation. Baseline mucosal eosinophil numbers in non-inflamed colonic tissue were significantly higher in responders to vedolizumab induction therapy when compared to primary non-responders (69 [34–138] vs. 24 [18–28] eosinophils/high-power field, respectively, p < 0.01). Baseline serum eotaxin-1 levels in the discovery cohort were significantly elevated in responders, compared to primary non-responders (0.33 [0.23–0.44] vs. 0.20 [0.16–0.29] ng/mL, p < 0.01). Prediction models based on mucosal eosinophil counts and serum eotaxin-1 showed an area under the curve (AUC) of 0.90 and 0.79, respectively. However, the predictive capacity of baseline serum eotaxin-1 levels could not be validated in the GEMINI cohort. Mucosal eosinophil abundance in non-inflamed colonic tissue was associated with response to vedolizumab induction therapy in patients with IBD. Future studies are warranted to further validate the potential value of mucosal eosinophils and serum eotaxin-1 as biomarkers for response to vedolizumab therapy.
Background Use of inflammatory biomarkers is common practice in ulcerative colitis (UC) management1. This study examined the utility of faecal calprotectin (FCP), C-reactive protein (CRP), and albumin biomarkers and their combination, for predicting outcomes of clinical remission and disease control (composite of clinical, endoscopic and histologic disease activity measures2) in patients (pts) with UC under therapy with vedolizumab (VDZ) or adalimumab (ADA) in the VARSITY study. Methods VARSITY was a phase 3b, randomized, double-blind, double-dummy, active-control trial evaluating VDZ (anti-α 4β 7 integrin) vs ADA (anti-tumour necrosis factor-α) treatment in pts aged 18–85 years with moderate-to-severe UC (NCT02497469; EudraCT:2015-000939-33). Pts received either VDZ IV infusions (300 mg) on Day 1 and at Weeks (WKs) 2, 6, 14, 22, 30, 38, and 46 or ADA SC injections (40 mg), total dose 160 mg at WK1, 80 mg at WK2, and 40 mg every 2 weeks thereafter until WK50. In this post hoc analysis of data from 769 pts, the probability of clinical remission (total Mayo score ≤2, no subscore >1) and disease control (pt-reported outcome-2 [PRO2, Mayo subscores of stool frequency and rectal bleeding]; Mayo endoscopic subscore ≤1 [endoscopic improvement], and Robarts Histopathology Index score <5, [absence of histologic active disease]) were assessed at WK52 based on baseline and WK14 levels of dichotomized FCP (high-risk: ≥100 µg/g), CRP (high-risk: ≥5mg/L), and albumin (high-risk: <45 g/L) including the composite of high-risk CRP and FCP termed ‘inflammatory burden’ (IB). Results In comparison with biomarkers measured at baseline, FCP at WK14 was the most predictive of WK52 clinical remission after VDZ or ADA treatment3; WK14 FCP was also predictive of disease control using a combined endpoint of PRO2, endoscopy and histologic remission/response. VDZ-treated pts with low-risk FCP (<100 µg/g) at WK14 had a 76% chance of achieving WK52 clinical remission vs 35% for pts with high-risk FCP (70% vs 33% for ADA-treated pts with low and high-risk FCP, respectively). VDZ-treated pts with IB (high-risk levels of FCP and CRP) at WK14 had a 16% chance of clinical remission at WK52 vs a 57% probability for this endpoint in pts without IB at WK14; the risk difference for this composite biomarker was 42% (Table). Conclusion The addition of CRP to FCP as a composite biomarker of IB at WK14 after treatment initiation can be a useful negative predictor of pts who are likely to achieve significant long-term benefits, including remission and disease control, with VDZ or ADA treatment. References 1. Turner D, et al. Gastroenterology 2021;160(5):1570-38. 2. Danese S, et al. J Crohn’s Colitis 2021;15(Suppl1):S305–S305. 3. Dulai PS, et al. Gastroenterology 2021;160(6):S-46–7.
Vedolizumab blocks integrin alpha4/beta7 interaction with MAdCAM-1 on intestinal vascular endothelial cells. It is believed to treat inflammatory bowel disease (IBD) by preventing alpha4/beta7+ cells in blood from entering the intestinal mucosa. By CyTOF and flow cytometry, we found high expression of alph4/beta7 on nearly all myeloid dendritic cells in the blood. Flow cytometry was also performed on colon biopsies from 71 IBD patients on vedolizumab matched 1:1 with similar biopsies from 71 matched IBD patients not on vedolizumab. In the colon, vedolizumab use was associated with significantly fewer intramucosal myeloid dendritic cells (CD1c+, CD14−, CD11c+, HLA-DR+, Wilcoxon p=0.000001) in patients responsive to vedolizumab, but not in non-responders, relative to their respective controls. Fewer intramucosal naïve B (IgD+, Wilcoxon p=0.0001) and CD4 T cells (CD45RA+, Wilcoxon p=0.001) were also observed, regardless of treatment efficacy. No differences were observed in the frequency of other T or B cell subsets, including CD8 T cells, effector T cells, plasma cells and memory B cells expressing different immunoglobin isotypes, suggesting that they have an alternative means of recruitment not present among naïve lymphocytes, such as integrin alpha4/beta1, which binds VCAM-1. Thus we find no evidence that that vedolizumab functions by preventing effector lymphocytes from entering the intestinal mucosa. We instead associated vedolizumab use with fewer colonic naïve lymphocyte and myeloid dendritic cells. The latter is of particular interest, as it alone correlates with clinical response to this therapy. Supported by a collaborative research agreement with Takeda Pharmaceuticals
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