Α4β7 Integrin Research Articles

Spondyloarthritis with inflammatory bowel disease: the latest on biologic and targeted therapies.

Spondyloarthritis (SpA) encompasses a heterogeneous group of chronic inflammatory diseases that can affect both axial and peripheral joints, tendons and entheses. Among the extra-articular manifestations, inflammatory bowel disease (IBD) is associated with considerable morbidity and effects on quality of life. In everyday clinical practice, treatment of these conditions requires a close collaboration between gastroenterologists and rheumatologists to enable early detection of joint and intestinal manifestations during follow-up and to choose the most effective therapeutic regimen, implementing precision medicine for each patient's subtype of SpA and IBD. The biggest issue in this field is the dearth of drugs that are approved for both diseases, as only TNF inhibitors are currently approved for the treatment of full-spectrum SpA-IBD. Janus tyrosine kinase inhibitors are among the most promising drugs for the treatment of peripheral and axial SpA, as well as for intestinal manifestations. Other therapies such as inhibitors of IL-23 and IL-17, phosphodiesterase 4 inhibitor, α4β7 integrin blockers and faecal microbiota transplantation seem to only be able to control some disease domains, or require further studies. Given the growing interest in the development of novel drugs to treat both conditions, it is important to understand the current state of the art and the unmet needs in the management of SpA-IBD.

Notch signaling drives intestinal graft-versus-host disease in mice and nonhuman primates.

Notch signaling promotes T cell pathogenicity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) in mice, with a dominant role for the Delta-like Notch ligand DLL4. To assess whether Notch's effects are evolutionarily conserved and to identify the mechanisms of Notch signaling inhibition, we studied antibody-mediated DLL4 blockade in a nonhuman primate (NHP) model similar to human allo-HCT. Short-term DLL4 blockade improved posttransplant survival with durable protection from gastrointestinal GVHD in particular. Unlike prior immunosuppressive strategies tested in the NHP GVHD model, anti-DLL4 interfered with a T cell transcriptional program associated with intestinal infiltration. In cross-species investigations, Notch inhibition decreased surface abundance of the gut-homing integrin α4β7 in conventional T cells while preserving α4β7 in regulatory T cells, with findings suggesting increased β1 competition for α4 binding in conventional T cells. Secondary lymphoid organ fibroblastic reticular cells emerged as the critical cellular source of Delta-like Notch ligands for Notch-mediated up-regulation of α4β7 integrin in T cells after allo-HCT. Together, DLL4-Notch blockade decreased effector T cell infiltration into the gut, with increased regulatory to conventional T cell ratios early after allo-HCT. Our results identify a conserved, biologically unique, and targetable role of DLL4-Notch signaling in intestinal GVHD.

A microbiota-modulated checkpoint directs immunosuppressive intestinal T cells into cancers.

Antibiotics (ABX) compromise the efficacy of programmed cell death protein 1 (PD-1) blockade in cancer patients, but the mechanisms underlying their immunosuppressive effects remain unknown. By inducing the down-regulation of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) in the ileum, post-ABX gut recolonization by Enterocloster species drove the emigration of enterotropic α4β7+CD4+ regulatory T 17 cells into the tumor. These deleterious ABX effects were mimicked by oral gavage of Enterocloster species, by genetic deficiency, or by antibody-mediated neutralization of MAdCAM-1 and its receptor, α4β7 integrin. By contrast, fecal microbiota transplantation or interleukin-17A neutralization prevented ABX-induced immunosuppression. In independent lung, kidney, and bladder cancer patient cohorts, low serum levels of soluble MAdCAM-1 had a negative prognostic impact. Thus, the MAdCAM-1-α4β7 axis constitutes an actionable gut immune checkpoint in cancer immunosurveillance.

Alpha4 beta7 integrin controls Th17 cell trafficking in the spinal cord leptomeninges during experimental autoimmune encephalomyelitis.

Th1 and Th17 cell migration into the central nervous system (CNS) is a fundamental process in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS). Particularly, leptomeningeal vessels of the subarachnoid space (SAS) constitute a central route for T cell entry into the CNS during EAE. Once migrated into the SAS, T cells show an active motility behavior, which is a prerequisite for cell-cell communication, in situ reactivation and neuroinflammation. However, the molecular mechanisms selectively controlling Th1 and Th17 cell trafficking in the inflamed leptomeninges are not well understood. By using epifluorescence intravital microscopy, we obtained results showing that myelin-specific Th1 and Th17 cells have different intravascular adhesion capacity depending on the disease phase, with Th17 cells being more adhesive at disease peak. Inhibition of αLβ2 integrin selectively blocked Th1 cell adhesion, but had no effect on Th17 rolling and arrest capacity during all disease phases, suggesting that distinct adhesion mechanisms control the migration of key T cell populations involved in EAE induction. Blockade of α4 integrins affected myelin-specific Th1 cell rolling and arrest, but only selectively altered intravascular arrest of Th17 cells. Notably, selective α4β7 integrin blockade inhibited Th17 cell arrest without interfering with intravascular Th1 cell adhesion, suggesting that α4β7 integrin is predominantly involved in Th17 cell migration into the inflamed leptomeninges in EAE mice. Two-photon microscopy experiments showed that blockade of α4 integrin chain or α4β7 integrin selectively inhibited the locomotion of extravasated antigen-specific Th17 cells in the SAS, but had no effect on Th1 cell intratissue dynamics, further pointing to α4β7 integrin as key molecule in Th17 cell trafficking during EAE development. Finally, therapeutic inhibition of α4β7 integrin at disease onset by intrathecal injection of a blocking antibody attenuated clinical severity and reduced neuroinflammation, further demonstrating a crucial role for α4β7 integrin in driving Th17 cell-mediated disease pathogenesis. Altogether, our data suggest that a better knowledge of the molecular mechanisms controlling myelin-specific Th1 and Th17 cell trafficking during EAE delevopment may help to identify new therapeutic strategies for CNS inflammatory and demyelinating diseases.

EFFICACY AND SAFETY OF VEDOLIZUMAB AND TUMOR NECROSIS FACTOR INHIBITORS IN THE TREATMENT OF STEROID-REFRACTORY MICROSCOPIC COLITIS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Tumor necrosis factor (TNF-α) inhibitors and the α4β7 integrin antagonist, vedolizumab have been investigated as a treatment option for patients with steroid-refractory microscopic colitis (MC) with controversial findings.

ARTHRITIS AND ARTHRALGIA AS EXTRAINTESTINAL MANIFESTATIONS IN PATIENTS WITH INFLAMMATORY BOWEL DISEASE TREATED WITH VEDOLIZUMAB: A META-ANALYSIS

Vedolizumab is a humanized gut selective drug that specifically targets α4β7 integrin and has been used successfully in the treatment of Inflammatory Bowel Disease (IBD). Although Vedolizumab is an effective treatment for IBD and acts specifically on the gastrointestinal system, some studies have reported extraintestinal manifestations as adverse events. One of the most frequently reported non-infectious adverse events is articular manifestations. However, it is difficult to know for sure whether the joint symptoms are due to the vedolizumab adverse event or due to extraintestinal symptoms of the disease itself.

THE EFFECT OF VEDOLIZUMAB ON CD8 T CELL REPERTOIRE HOMOGENEITY AND BLOOD-GUT TRAFFICKING IN PATIENTS WITH INFLAMMATORY BOWEL DISEASE

Inflammatory bowel disease (IBD) causes T cell infiltration of the intestinal mucosa, but the heterogeneity of these cells is not understood at a clonal level. The drug vedolizumab is believed to treat IBD by blocking the entry of circulating integrin α4β7+ T cells into the intestinal mucosa.

Force-Regulated Calcium Signaling of Lymphoid Cell RPMI 8226 Mediated by Integrin α4β7/MAdCAM-1 in Flow.

MAdCAM-1 binds to integrin α4β7, which mediates the rolling and arrest of circulating lymphocytes upon the vascular endothelia during lymphocytic homing. The calcium response by adhered lymphocytes is a critical event for lymphocyte activation and subsequent arrest and migration under flow. However, whether the interaction of integrin α4β7 /MAdCAM-1 can effectively trigger the calcium response of lymphocytes remains unclear, as well as whether the fluid force affects the calcium response. In this study, we explore the mechanical regulation of integrin α4β7-induced calcium signaling under flow. Flou-4 AM was used to examine the calcium response under real-time fluorescence microscopy when cells were firmly adhered to a parallel plate flow chamber. The interaction between integrin α4β7 and MAdCAM-1 was found to effectively trigger calcium signaling in firmly adhered RPMI 8226 cells. Meanwhile, increasing fluid shear stress accelerated the cytosolic calcium response and enhanced signaling intensity. Additionally, the calcium signaling of RPMI 8226 activated by integrin α4β7 originated from extracellular calcium influx instead of cytoplasmic calcium release, and the signaling transduction of integrin α4β7 was involved in Kindlin-3. These findings shed new light on the mechano-chemical mechanism of calcium signaling in RPMI 8226 cells induced by integrin α4β7.

Radioimmune Imaging of α4β7 Integrin and TNFα for Diagnostic and Therapeutic Applications in Inflammatory Bowel Disease

Imaging using radiolabelled monoclonal antibodies can provide, non-invasively, molecular information which allows for the planning of the best treatment and for monitoring the therapeutic response in cancer, as well as in chronic inflammatory diseases. In the present study, our main goal was to evaluate if a pre-therapy scan with radiolabelled anti-α4β7 integrin or radiolabelled anti-TNFα mAb could predict therapeutic outcome with unlabelled anti-α4β7 integrin or anti-TNFα mAb. To this aim, we developed two radiopharmaceuticals to study the expression of therapeutic targets for inflammatory bowel diseases (IBD), to be used for therapy decision making. Both anti-α4β7 integrin and anti-TNFα mAbs were successfully radiolabelled with technetium-99m with high labelling efficiency and stability. Dextran sulfate sodium (DSS)-induced colitis was used as a model for murine IBD and the bowel uptake of radiolabelled mAbs was evaluated ex vivo and in vivo by planar and SPECT/CT images. These studies allowed us to define best imaging strategy and to validate the specificity of mAb binding in vivo to their targets. Bowel uptake in four different regions was compared to immunohistochemistry (IHC) score (partial and global). Then, to evaluate the biomarker expression prior to therapy administration, in initial IBD, another group of DSS-treated mice was injected with radiolabelled mAb on day 2 of DSS administration (to quantify the presence of the target in the bowel) and then injected with a single therapeutic dose of unlabelled anti-α4β7 integrin or anti-TNFα mAb. Good correlation was demonstrated between bowel uptake of radiolabelled mAb and immunohistochemistry (IHC) score, both in vivo and ex vivo. Mice treated with unlabelled α4β7 integrin and anti-TNFα showed an inverse correlation between the bowel uptake of radiolabelled mAb and the histological score after therapy, proving that only mice with high α4β7 integrin or TNFα expression will benefit of therapy with unlabelled mAb.

Cost effective and reliable cell based ELISA as an alternative method of flow cytometry for assessment of binding activity of Vedolizumab

Vedolizumab is a humanized monoclonal antibody used for inflammatory bowel disease treatment. Vedolizumab binds to the α4β7 integrin complex and inhibits its binding to mucosal addressin cell adhesion molecule-1 (MAdCAM-1). To evaluate the binding efficacy and quality control check of Vedolizumab, flow cytometry is performed by using HuT78 cells. As we know, flow cytometer is costly and require high equipment maintenance with a designated technical manpower to handle it. In this regard, the aim of study was to develop and validate an economical, simple and efficient cell based ELISA assay for potency estimation of Vedolizumab which has not been reported in any pharmacopoeia. The proposed bioassay method was optimized by investigating Vedolizumab binding to α4β7 integrin which is expressed by HuT78 cells. The validation of this method was done at different parameters including specificity, linearity, range, repeatability, precision, and accuracy. The Vedolizumab binding by ELISA results were found specific for Vedolizumab with linearity (R2 = 0.99) and precision (%Geometric Coefficient of variance) observed for repeatability and intermediate precision were 3.38% and 2.6% respectively. The relative bias was calculated as 8.68% for repeated performances by different analysts and found in accordance with parameter of accuracy as per various pharmacopoeial guidelines. The developed method is established as robust, effective, and less expensive than high maintenance setup like flow cytometry based assay.

P803 Plasma N-glycan biomarkers predict patient Response to Vedolizumab treatment for Crohn’s Disease

Abstract Background Vedolizumab (VDZ) is a monoclonal antibody directed against α4β7 integrin used to treat Crohn’s disease, which has proven to be efficacious in phase 3 clinical trials¹ and in real-world studies². However, there is a need for reliable biomarkers to predict whether an individual patient will respond to VDZ treatment. Glycosylation changes have been associated with CD, but have never been studied as potential predictors of remission to biological therapy³. A comparison of plasma N-glycan profiles between responders and non-responders to VDZ was used to detect potential biomarkers to response. Methods Plasma samples before (t1) and after (t2) initiation of vedolizumab treatment (mean follow up time at t2 215 ± 61 days) were taken from 58 patients with Crohn’s disease. They were analysed by high-performance liquid chromatography with mass spectrometry. Response to VDZ was assessed by a combination of clinical and endoscopic outcomes and was observed in 34 of 58 patients. 89 direct glycan traits met the criteria for quantification and were extracted from the data via LacyTools. Consequently, 21 derived glycan traits were calculated by combining direct traits with shared structural similarities. Correcting for age and sex, the direct and derived traits were tested across responses using logistic regression and cross-validation to determine which traits at t1 are predictive of response (p-value < 0.05) and traits at t2 are markers of response (p-value < 0.05). Results Two glycans, MAN6 (0.65 AUC) and FA2G2S2 (0.7 AUC) were higher in responders prior to treatment and moderate predictors of response, with no improvement in a combined model (figure 1A). Congruent to previous studies, galactosylation levels increased in responders after treatment. Overall, 17 direct traits and 4 derived traits were markers of response after treatment and collectively proved to be good predictors of response (0.80 AUC) (figure 1B). Conclusion This study has demonstrated multiple N-glycans are indicators of future response to VDZ treatment, with the potential to guide clinicians in determining the most appropriate form of treatment for individuals. These data require to be validated in the future; and to be assessed alongside other emerging biomarkers.

P655 MadCAM1 Negativity of Lamina Propria Endothelial Cells is Associated with Non-Response to Vedolizumab in Inflammatory Bowel Disease Patients

Abstract Background Vedolizumab (VDZ), a monoclonal antibody against α4β7 integrin has been shown to be effective in inducing and maintaining remission in inflammatory bowel disease (IBD). By blocking α4β7, it is preventing the homing of lymphocytes through binding to mucosal vascular adressin cell adhesion molecule 1 (MadCAM1) localised on the intestinal endothelial cells. We have previously reported that MadCAM1 is expressed to various extent on lamina propria endothelial cells of IBD patients and that this expression is stable over time. The aim of the present study was to analyse whether expression of MadCAM1 was related to the response to VDZ in IBD patients. Methods All IBD patients treated with VDZ in one referral IBD centre were included. The biopsies or resection specimen from the inflamed intestinal tissue were stained by immunohistochemistry for MadCAM1 expression. Clinical response to vedolizumab was assessed in patients with the minimal treatment duration of 10 weeks and the response rate between patients with positive and negative MadCAM1 were analyzed by Fisher`s exact test. Results In total, 92 IBD patients were treated with VDZ; for 83 of them intestinal biopsies or surgical specimen were available for assessment of MadCAM1 expression. In four patients (5%) no expression of MadCAM1 was detected, remaining 79 patients expressed MadCAM1 to various extent. Overal, 30 patients (36%) were non-responders to VDZ treatment. With regards to MadCAM1 expression, 67% of patients expressing MadCAM1 responded to VDZ (53 patients) while none of the patients negative for MadCAM1 responded to treatment (p=0.0171). Conclusion Lack of MadCAM1 expression in intestinal endothelium is associated with clinical non-response to vedolizumab.

P401 Concomitant azathioprine treatment effects vedolizumab treatment persistence in Crohn’s Disease but not in Ulcerative Colitis

Abstract Background Vedolizumab is a monoclonal antibody against integrin α4β7 that is being used for the treatment of moderate to severe Ulcerative Colitis (UC) and Crohn’s Disease (CD). Recent studies have shown conflicting results for the effect of concomitant azathioprine use with vedolizumab monotherapy. In this single center cohort study, we investigated the effect of concomitant azathioprine treatment on vedolizumab drug persistence in UC and CD treatment. Methods We performed a retrospective review of all adult (≥18 years) UC and CD patients started on VDZ at our infusion center. Data collection included baseline demographics, concomitant azathioprine therapy, VDZ therapy and disease activity scores using the partial Mayo score and Harvey Bradshaw Score. Data were obtained from the digital medical record. The primary outcome measure was VDZ persistence, represented in Kaplan-Meier analysis. This analysis assessed persistence on every 8 week dose regimen. Results This single center cohort included 142 VDZ treated UC (n=64) and CD (n=78) patients. All patients had a history of at least one anti-TNF treatment: Mean age 38.9±12.5 years and male gender 84 (59.2%). Median disease duration was 6±1.6 years. 6 Patients were excluded from the analysis since VDZ therapy has been stopped due to side effects. Mean duration of VDZ treatment in Crohn’s disease was 96.5±69.2 weeks and in UC was 72.1±60.5 weeks. Concomitant azathioprine therapy in CD increased VDZ persistence rate. However, in UC concomitant azathioprine therapy did not effect VDZ persistence rate. Conclusion The real-world data collected in this study demonstrate that concomitant azathioprine treatment increase the VDZ persistence rate in Crohn’s disease. However, concomitant azathioprine treatment does not effect the VDZ persistence rate in UC patients.

P025 Colonic rather than ileal expression of ITGA4/ITGB7 correlates with local intestinal inflammation in IBD

Abstract Background Lymphocyte trafficking to the inflamed gut is one of the hallmarks of Inflammatory Bowel Disease (IBD) pathology. Integrin a4b7 and its ligand MADCAM1 play an important role in targeting immune cells in the bloodstream to mucosal tissues and blocking this pathway using the anti-a4b7 monoclonal antibody Vedolizumab (VDZ) proved to be an effective treatment in IBD. However, VDZ is most efficient in treatment of Ulcerative Colitis (UC) and of colonic rather than ileal Crohn’s Disease (CD), for which the reasons have not been completely understood. Here we sought to compare the expression of ITGA4, ITGB7 and MADCAM1 in gut tissue biopsies from small and large bowel with respect to the underlying severity of tissue inflammation. Methods Differential gene expression analysis was conducted using bulk RNA Sequencing data generated from gut tissue biopsies of the large and small intestine of 611 CD and 315 UC patients enrolled in a multicentred longitudinal Study of a Prospective Adult Research Cohort with IBD (SPARC IBD) obtained from the IBD Plexus program of the Crohn’s and Colitis Foundation. Gene expression levels of ITGA4, ITGB7 and MADCAM1 were compared across ileal, colonic and rectal segments of the intestine and data were then linked to available measures of local inflammation. Results ITGA4, ITGB7 and MADCAM1 were expressed at comparable levels in large vs small bowel biopsies. Expression of MADCAM1 was significantly increased in both ileal and colonic biopsies from patients with moderate to severe CD based on segmental or composite endoscopy score (SES-CD) across all bowel segments. Expression of both ITGA4 and ITGB7 was similarly increased in colonic biopsies of moderate/severe CD patients, whereas only minor changes were observed for both genes in ileal biopsies. Similar findings were obtained from UC patients, where expression of MADCAM1 was significantly increased in inflamed or ulcerated biopsies from both sigmoid colon and cecum as compared to normal appearing biopsies. Expression of ITGA4 and ITGB7 was only increased in inflamed/ulcerated biopsies of the sigmoid colon but not the cecum and correlated with the modified Mayo endoscopic score (MMES). Conclusion Our analysis suggests that influx of leukocytes to inflamed tissue via ITGA4/ITGB7 and MADCAM1 interactions is more common in the distal colon compared to proximal colon or ileum. This provides a possible mechanistic explanation as to why VDZ is most effective in patients with colonic IBD. Further work is needed to understand the differential regulation of cell trafficking to different regions of the gut.

P650 Integrin expression patterns of patients with IBD treated with vedolizumab.

Abstract Background Anti-α4β7 integrin monoclinic antibody vedolizumab is an effective treatment for moderate and severe Ulcerative Colitis and Crohn’s Disease. Occasionally vedolizumab-treated patients experience articular extraintestinal manifestations, in the form of arthralgias, which could be attributed to lymphocyte tracking modification caused by vedolizumab. This study aims to describe α4β7 andα4β1 integrin expression on circulating lymphocytes and the effect of vedolizumab on integrin expression, as well asto identify expression patterns associated with arthralgias under vedolizumab. Methods A cross-sectional study was conducted. Peripheral blood was collected in EDTA-coated bottles before a scheduled drug administration. Expression of α4β7 and α4β1 integrins on CD4+T, CD8+T, B and plasma cells was studied by flow cytometry (DX Flex, BC), using CD3, CD4, CD8, CD19,CD138, CD49d (α4), β7, CD29 (β1). Kaluza C software and SPSS23 were used for analysis. Results In total, 40 IBD patients (16 of them treated withvedolizumab) and 8 healthy controls were included. There was a higher percentage of α4β1expressing lymphocytes compared to α4β7+ ones (P<0.001) (figure 1). Vedolizumab-treated patients had lower percentages of integrin-expressing B cells (α4β7 P=0.001 vs controls, α4β7 P=0.052 vs non-vedolizumab IBD, α4β1 P=0.002 vs controls, α4β1 P=0.015 vs non-vedolizumab IBD) and α4β1 plasma cells (P=0.013 vs non-vedolizumab IBD) (figure 2). In patients treated with vedolizumab with arthralgias, α4β7 expression on B-cells was more suppressed, whereas α4β1 expression on plasma cells was less suppressed, compared to those that had not developed arthralgias, but not in a statistically significant level (figure 3). Conclusion Patients treated with vedolizumab presented different patterns of integrin expression on circulating B cells. Manifestation of arthralgias under vedolizumab may be associated with a disruption of α4β7/α4β1 proportion. Funding: This study was funded through a research grant from the Greek IBD study group (EOMIFNE) to G.B. EOMIFNE Grant: 2020EOMIFNEp1

P689 Predictive transcriptional signatures associated to vedolizumab therapy response in patients with ulcerative colitis

Abstract Background Vedolizumab is one of the current treatments for patients with inflammatory bowel disease (IBD). The efficacy and safety, along with its gut specificity, make this drug an appealing therapeutic option for IBD patients with moderate to severe disease. However, as observed for other biologic treatments, a significant proportion of patients do not have an initial response to vedolizumab treatment. Currently, there is a lack of reliable predictive tools for vedolizumab treatment response, although this would help to alleviate the socioeconomic costs derived from this disease. For that reason, the primary aim of this study is to show putative transcriptional signatures associated with vedolizumab treatment response. Methods For the realization of this study, we used RNA-seq datasets from the Gene Expression Omnibus (GEO) database: GSE191328. This dataset includes samples from peripheral blood cells from responder and non-responder ulcerative colitis (UC) patients treated with vedolizumab and infliximab at baseline. Gene Set Enrichment Analysis (GSEA) was performed to compare the differential expression and the enrichment analysis was calculated using ssGSEA of the different groups under study. Results The analysis of the transcriptome of peripheral blood cells from responder (R) and non-responder (NR) vedolizumab-treated patients at baseline revealed interesting enrichment results. We found 20 gene sets positively enriched in NR versus R and only 9 gene sets negatively enriched in the same phenotypes. In order to find vedolizumab specific transcriptional signatures, we performed a similar analysis in samples from infliximab-treated patients. After that second round of analysis, we observed that around 50% of the enriched gene sets were similar for both biological treatments. Nevertheless, several interesting biological functions such as peroxisome function, reactive oxygen function or beta-catenin signalling are specifically enriched in NR patients to vedolizumab treatment. Conclusion Our data suggest that vedolizumab NR patients specifically show a transcriptional enrichment profile, which differs from vedolizumab R patients. Also, the comparative analysis with infliximab-treated patients reveals that those specific transcripts are modulated in response to this α4β7 integrin antibodies in peripheral blood cells. Therefore, we found a solid system to search for vedolizumab therapy predictive response markers using low invasive techniques.

P623 Mucosal eosinophils as markers of post-induction vedolizumab response in paediatric Ulcerative Colitis

Abstract Background Vedolizumab (VDZ) is commonly used as an off-label therapy in children with ulcerative colitis (UC) but no predictive factors of response are available. Vedolizumab binds α4β7 integrin and blocks the migration of T-lymphocytes and other cells, including eosinophils, which are involved in the UC inflammatory process. The aim of our study was to explore the predictive value of pre-therapy mucosal eosinophil count on the response to vedolizumab induction therapy in a paediatric population with UC Methods This is a retrospective, monocentric study, including children with UC treated with VDZ in the Paediatric Gastroenterology Unit of Policlinico Umberto I Hospital – Sapienza University of Rome. Histopathological data were analyzed for eosinophil counts in high power fields (hpf) in the cecum, transverse colon, sigma, and rectum prior to VDZ treatment. Clinical remission and response were evaluated at week 14 based on the PUCAI score. Results Twenty-five UC patients treated with VDZ were enrolled. All patients had failed previous anti-TNF therapy. Median baseline eosinophil count was 21 eo/hpf (5-60) in the cecum, 20 eo/hpf (6-68) in transverse colon, 44 eo/hpf (12-77) in sigma and 31 eo/hpf (9-67) in rectum. Baseline median eosinophil mucosal count in sigma was significantly higher in patients in remission (51[30-82]/ vs. 19[8.5–46] eosinophils/hpf, P<0.05) and clinical response (46[23-79]/ vs. 14[6–45] eosinophils/hpf, P<0.05) at week 14, compared to non-responders. At univariate and multivariate analysis, the number of eosinophils in sigma was confirmed to predict clinical remission [OR=1.0 (95%CI:1.00-1.087), p: 0.03), also independently to concomitant steroid use [OR: 1.06 (95%CI: 1.00-1.122) p: 0.047). The ROC curve identified a risk threshold value for eosinophil count in sigma >23 eosinophils/hpf, with a sensitivity of 85.7% and specificity of 66.7% (Youden’s index 0.83) with an area under the curve (AUC) of 0.778 Conclusion Mucosal eosinophil abundance in sigma may predict remission to vedolizumab induction in paediatric UC. More studies are warranted to confirm these preliminary results and further investigate the role of mucosal eosinophils as a marker of therapeutic response and in the pathogenesis of UC

P647 Outcomes following the use of vedolizumab first line versus second line in Ulcerative Colitis: a single centre experience

Abstract Background With the introduction of an increasing number of biological therapies for Ulcerative Colitis (UC), decisions regarding the sequencing of treatment continues to dominate current management strategies. In this single centre study, we assessed outcomes in patients with UC following first line treatment with the α4β7 integrin blocker vedolizumab (VDZ) therapy vs second line VDZ therapy following anti-Tumour Necrosis Factor (anti-TNF) exposure. Methods All patients exposed to VDZ either first line or second line were identified via our Inflammatory Bowel Disease (IBD) registry. Data was collected retrospectively between June 2015 and June 2021. Baseline demographics, disease extent and activity scores, treatment continuation, and colectomy rates were analysed over a 52-week period. Results A total of 100 patients were included in the study, age (median [IQR]) 52 [37-64] years; 52% male 48% female). VDZ as first line biologic included 38 patients, age (median [IQR]) 51 [34-65] years; 50% male and 50% female). The VDZ as second line (Ant-TNF exposed) group included 62 patients, age (median [IQR]) 52 [38-61] years; 53% male and 47% female). The Anti-TNF exposed group included infliximab 26 (43.3%), adalimumab 22 (35.5%), golimumab 12 (19.2%) and both infliximab and adalimumab 2 (3%). Disease extent (Montreal classification: E1:proctitis, E2: left-sided or E3: extensive disease) in the VDZ first line group (E1 (13.1%), E2 (61.6%) and E3 (26.3%)) versus VDZ second line (E1 (11.3%), E2 (61.3%) and E3 (27.4%)). In the VDZ first line group (38 cases), the outcomes at 52 weeks were: Treatment continuation 24 (63%), colectomy 2 (5%) and treatment switch in 12 (32%) to infliximab (4), Adalimumab (3), Ustekinumab (4) and Tofacitinib (1). In comparison, the Anti-TNF exposed group (62 cases) outcomes at 52 weeks were: Treatment continuation 46 (74%), colectomy 5 (8%) and treatment switch in 11 (18%) to Adalimumab (2), Ustekinumab (4) and Tofacitinib (5). A total of 7 of patients underwent colectomy during the 52 week follow up period. By 52 weeks, 94.8% (36/38) were colectomy free in the VDZ first line group versus 92% (57/62) in the anti-TNF exposed group, which was not statistically significant (odds ratio (OR) of having a colectomy in the VDZ1st line group vs the VDZ 2nd line group was 0.61(p=0.58)). Conclusion Our study evaluated real-world treatment continuation and colectomy-free outcomes for VDZ as first and second line biologic therapy (Anti-TNF exposed) in patients with ulcerative colitis and confirmed its effectiveness in both treatment groups.

DOP01 The effect of vedolizumab on CD8 T cell repertoire homogeneity and blood-gut trafficking in patients with inflammatory bowel disease

Abstract Background Inflammatory bowel disease (IBD) causes T cell to infiltrate intestinal mucosa, but the heterogeneity of these cells is not understood at a clonal level. The anti-integrin α4β7 agent vedolizumab is believed to treat IBD by blocking this T cell infiltration from blood. Methods To understand the clonal distribution of T cells in IBD and how this is affected by vedolizumab, we studyined the T cell receptor (TCR) repertoire in CD8+ T cell subsets sorted from blood samples and colon mucosal biopsies via FACS. Inflamed or uninflamed colon segments from 15 ulcerative colitis and 13 Crohn’s disease patients were compared to colon biopsies from 11 people without IBD. In peripheral blood, we profiled purified α4β7+, α4β7- effector/memory, CD45RA+ terminal effector/memory (TEMRA) CD8 T cells, and mucosal-associated invariant T (MAIT) cells. In a separate cohort of 13 IBD patients, samples were obtained before and during vedolizumab therapy to determine its effect on the diversity and overlap of the TCR repertoires of blood and colon CD8+ T cells. Results CD8 TCR diversity in the mucosa and peripheral blood did not correlate with inflammation. CD8 TCR repertoire overlap between any two anatomically distinct locations of a person’s colon was consistently high, though often lower between inflamed and uninflamed sites. Repertoire overlap was also seen between the colon and each peripheral blood subpopulation studied, with the highest overlap seen for integrin α4β7+ T cells and the lowest for MAIT cells. Inflamed tissue overlapped more than uninflamed with each blood subpopulation. Vedolizumab did not affect the overlap between colon CD8+ T cells and circulating α4β7+ CD8 T cells, nor their TCR diversity, regardless of treatment efficacy. Indeed, flow cytometry revealed no relative depletion of effector/memory T cells in the colons of vedolizumab recipients. Instead, vedolizumab caused the depletion of rare naïve mucosal T cells and dendritic cells (DC) from the colonic mucosa. Conclusion CD8 T cell clones are spread homogenously throughout the colon. Although TCR repertoire overlap is greater within than between inflamed and uninflamed colon segments, a similar diversity of TCRs in both argues against local clonal expansion being the main source of excess T cells in inflamed mucosa. Rather, our data reveal increased TCR overlap between blood and inflamed mucosa to support the significance of T cell trafficking in IBD pathogenesis, particularly concerning experienced α4β7+ T cell populations. However, we surprisingly found neither gross nor clonal evidence that blockade of this trafficking is the mechanism by which vedolizumab treats IBD, instead finding only naïve T cells and DC to be depleted from the colonic mucosa in response to vedolizumab.

P586 Vedolizumab in Mild to Moderate Crohn’s Disease Patients Naïve to Biological Therapy: a Multicentric Observational Study

Abstract Background Vedolizumab, a human monoclonal antibody that blocks integrin α4-β7, was approved for the management of Inflammatory Bowel Diseases. In real-world experience the number of patients using vedolizumab as first-line biological therapy was low, mainly in Crohn′s Disease (CD). This study aimed to evaluate the efficacy of vedolizumab exclusively in CD patients who were naïve to previous biologics, with mild to moderate disease. Additionally, we aimed to analyze the safety profile of vedolizumab, rates of mucosal healing, need for abdominal surgery and drug discontinuation over time in this specific population. Methods We performed a retrospective multicentric cohort study with patients with mild to moderate CD treated with VDZ who were naïve to previous biologics agents. These patients had clinical activity scores (Harvey-Bradshaw Index [HBI]) measured at baseline and weeks 12, 26, 52 as well as at the last follow-up. Clinical response was defined as a reduction ≥3 in HBI whereas clinical remission as HBI ≤4. Mucosal healing was defined as the complete absence of ulcers in control colonoscopies. Kaplan-Meier survival analysis was used to assess the persistence with vedolizumab over time. Results From a total of 72 patients (6 excluded) 53% (35/66) reached clinical remission at week 12. This percentage increased to 71.9% (46/64) at week 26, 88.1% (52/59) at week 52 and 81.8% (54/66) at the last follow-up visit. Clinical response was achieved in 72.7% (48/66), 92.2% (59/64), 95,1% (58/61) and 83.3% (55/66) in the same periods, respectively. Mucosal healing was achieved in 62.3% (33/57) of patients. Vedolizumab was well-tolerated and most adverse events were minor; 89.3% remained on vedolizumab after 52 weeks. During vedolizumab treatment, 3/66 patients underwent surgery. Conclusion Vedolizumab was effective in the management of patients with mild to moderate CD as first biological agent, with a remission rate of 88.1% after one year. Mucosal healing was observed in 62.3% of patients and major abdominal surgery was needed in only 4.5% of patients. This is one of the first international studies focused on the use of vedolizumab as a first-line biological treatment option in clinical practice in mild to moderate CD.