What question did this study set out to answer?

This research aims to examine how the gut microbiome changes in IBD patients undergoing treatment with vedolizumab and its connection to clinical outcomes.

January 23, 2026

P1343 Longitudinal Analysis of Gut Microbiome Alterations in IBD Patients Treated with Vedolizumab

Key Points

This research aims to examine how the gut microbiome changes in IBD patients undergoing treatment with vedolizumab and its connection to clinical outcomes.
Enrolled patients received intravenous vedolizumab induction and maintenance therapy.
Faecal samples were collected and analyzed using 16S rRNA sequencing at specified intervals.
Microbial composition was assessed against clinical outcomes such as remission and response indicators.
Distinct changes in gut microbiome composition linked to positive treatment outcomes were observed.
A decrease in Proteobacteria and specific genera like Escherichia-Shigella was noted in patients achieving clinical remission.
Specific microbial signatures correlated with treatment success were identified, particularly in Crohn’s disease patients.

Abstract

Abstract Background Accumulating evidence suggests that the gut microbiota can be associated with the therapeutic effectiveness of biologics for patients with inflammatory bowel disease (IBD), by modulating drug metabolism and immune responses. We prospectively investigated longitudinal changes of the gut microbial communities and their association with the therapeutic responses in Korean patients with IBD treated with vedolizumab (VDZ). Methods Patients with IBD were prospectively enrolled and were given intravenous VDZ induction (300 mg at weeks 0, 2, and 6) and maintenance therapy (300 mg every 8 weeks and every 4 weeks for inadequate responders). Faecal samples were collected at weeks 0, 14, and 54 and 16S rRNA sequencing data were analyzed using the QIIME2 platform (version 2023.9.2). As outcome variables, clinical remission (CREM), clinical response (CRES), endoscopic mucosal healing (MH) and biochemical response (BioRES) including faecal calprotectin (FC) were evaluated. Compositional differences in microbiome were analysed according to outcomes at weeks (W) 0, 14, and 54. Results A total of 64 patients, comprising 27 with ulcerative colitis (UC) and 37 with Crohn’s disease (CD), were enrolled. Therapeutic outcomes at W14 and W54 are summarized in table 1. In UC or CD patients who achieved CREM, distinct trends in phylum-level changes such as a decrease in the relative abundance of the phylum Proteobacteria and a decrease in the proportion of genera belonging to the phylum Proteobacteria, such as Escherichia-Shigella were observed over time compared to W0 (Figure 1). Consistent patterns were observed across all other treatment response indicators including CRES, MH and BioRES. Microbial changes shared between UC and CD in response to VDZ treatment, as well as contrasting microbial patterns distinguishing UC and CD were identified, including the family Veillonellaceae, the genus Bifidobacterium, the genus Escherichia-Shigella, and the genus Dialister. In patients with UC, the overall changes in microbial community structure after VDZ therapy were not substantial, and treatment responses to VDZ in CD patients were more related to the increase or decrease of specific bacteria rather than drastic changes in the overall community structure. Finally, in UC patients, genus-level analysis identified taxa consistently increasing in positive treatment outcome-achieving groups and in CD patients, distinct and consistent microbial signatures were observed in CREM- and CRES-achieving groups. Conclusion This longitudinal study demonstrates that VDZ therapy alters the gut microbiome of IBD patients, linking these changes to subjective and objective clinical outcomes. These changes could serve as potential biomarkers related to VDZ therapeutic response. Conflict of interest: Prof. Dr. Ye, Byong Duk: Byong Duk Ye reports consulting fees from AbbVie Korea, BMS Pharmaceutical Korea Ltd., Celltrion, Chong Kun Dang Pharm, CJ Red BIO, Curacle, Daewoong Pharm, Dong-A ST, Ferring Korea, Hanmi Pharmaceutical, Imscout, IQVIA, Johnson & Johnson, Johnson & Johnson Korea, Jeil Pharmaceutical Co., Kangstem Biotech, Korea Otsuka Pharm, Korea United Pharm, Lilly Korea, Medtronic Korea, NanoEntek, ORGANOIDSCIENCES Ltd., Pfizer Korea, Samsung Bioepis, Takeda, Takeda Korea and Yuhan speaker fees from AbbVie Korea, BMS Pharmaceutical Korea Ltd., Celltrion, Cornerstones Health, Curacle, Daewoong Pharm, Eisai Korea, Ferring Korea, IQVIA, Johnson & Johnson Korea, Pfizer Korea, Samsung Bioepis, and Takeda Korea and research support from Celltrion and Pfizer Korea. Yoon, Aran: No conflict of interest Kim, Kyuwon: No conflict of interest Oh, Kyunghwan: No conflict of interest Kim, Eun Sil: No conflict of interest Kim, Eun Hye: No conflict of interest Kim, Seungil: No conflict of interest Jeong, Jin-Yong: No conflict of interest Kweon, Mi-Na: No conflict of interest Hwang, Sung Wook: no conflicts Park, Sang Hyoung: No conflicts Byeon, Jeong-Sik: Clinical study grants from Olympus Co, GC genome, Pharmbio Korea Inc, and Taejoon Pharm. Clinical studies related to the grants include artificial intelligence endoscopy for colon polyp detection/diagnosis, cfDNA for colorectal cancer screening, and colonoscopy bowel preparation. I am a medical advisor of AINEX corporation, Korea, which is an AI endoscopy company.

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