The goal of this retrospective study is to learn about dosing patterns in patients starting subcutaneous vedolizumab administration and patient outcomes after starting subcutaneous administration.

Patients with IBD who are starting subcutaneous vedolizumab administration between September 1, 2023, and March 31, 2025, as part of normal patient care, will be retrospectively reviewed and analyzed.

Vedolizumab intravenous (IV) infusions have been a first-line treatment option for patients with inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC) for over ten years. Recently, vedolizumab has been approved by the Food and Drug Administration for subcutaneous (SC) administration in the United States, offering patients a more convenient treatment option with medication administration at home. Evidence, largely from European countries where the SC formulation of vedolizumab has been available since 2020, shows a durable and potentially improved clinical response when switching to the SC formulation. A high SC treatment persistence has been found, mainly above 80%. Additionally, many patients accept the transition to SC vedolizumab as a safe and feasible treatment option and noting that the shorter treatment duration was specifically advantageous.

Current evidence is limited by the minimal amount of data on patients transitioning from IV to SC vedolizumab. For treatment with vedolizumab IV to SC, large scale, real-life studies with long term follow-up are necessary. More research is needed to further evaluate predictors for a relapse when transitioning from IV to SC therapy that have been seen in previous studies, including older age, escalated IV dosing, fecal calprotectin >250 microgram/gram at baseline, and CRP > 2g/L at baseline. We must also evaluate patient clinical outcomes after switching from IV to SC vedolizumab or infliximab and potential predictors for a positive response. These results will drive clinical decisions and further understanding of treatment expectations.

There is also a large gap in available information on standard and escalated dosing patterns before and after switching from IV to SC vedolizumab. Minimal research has evaluated whether or not patients on escalated IV dosing maintain escalated dosing at the time of switch or initiate standard SC dosing. There is a pressing need to understand dosing patterns in patients transitioning from escalated IV dosing to SC administration and patient outcomes after switching to SC administration based on dosing.

The proposed study would meet current gaps in literature by evaluating 1) clinical outcomes in patients with CD and UC switching from IV to SC vedolizumab and 2) dosing patterns from standard or escalated IV dosing at baseline to standard or escalated SC dosing, including switching practices and outcomes.

Inclusion Criteria:

• Patients with Crohn's Disease or Ulcerative Colitis referred to start SC vedolizumab from a VUMC IBD provider and receive at least 1 dose of subcutaneous vedolizumab
• Age 18 years old or older

Exclusion Criteria:

• Patients prescribed SC vedolizumab from a non-VUMC provider
• Patients lost to follow-up or change in provider or medication before SC formulation started

Patients were identified if they were seen in the VUMC IBD clinic as part of normal clinical practice

Study does not meet the criteria for an Applicable Clinical Trial (ACT) under 42 CFR 11.22(b) as this study is not interventional (a clinical trial)