Descriptive : A 12-months multicenter, observational, prospective cohort study. Population : IBD patients under stable clinical and biological remission will be proposed to switch from the IV vedolizumab to the SC vedolizumab as part of routine care. All consecutive IBD patients in IBD centers participating in the study will be proposed to participate in the study during their regular outpatients' visits.

Objectives : The primary objective of DOPER study is to describe SC vedolizumab persistence after switching from IV vedolizumab to SC vedolizumab at month 12.

Number of patients : 400 patients in approximatively 31 sites in France. Recrutment period : The trial duration for each patient will be 1 year main. Endpoint : The primary endpoint is to assess the rate of persistence of SC vedolizumab at month 12 after switching from IV vedolizumab to SC vedolizumab.

Secondary Endpoint :

• Percentage of clinical remission at months 3 and 12, defined as a Partial Mayo Score (PMS) <2 with each sub-score (stool frequency, rectal bleeding, and physician rating of disease activity) of 1 or less for UC patients and as a Harvey Bradshaw Index (HBI) score ≤4 for CD patients
• Percentage of steroid free clinical remission at month 12
• Percentage of biological remission rates (defined as fecal calprotectin <250 μg/g and C-Reactive-Protein (CRP) <5 mg/L) at month 12
• Percentage of Patient-Reported Outcome 2 (PRO-2, defined as stool frequency and rectal bleeding for UC and stool frequency and abdominal pain for CD) response and remission at month 12
• Percentage of clinical relapse free rates at month 12
• Percentage of loss of response rates at month 12
• Mean change from baseline in PMS or HBI, CRP and fecal calprotectin compared to month 12
• Percentage of patients who switch back to previous IV vedolizumab therapy at month 12after switching from IV vedolizumab to SC vedolizumab
• Proportion of patients with positive antibodies (VDZ, ANA) comparing therapy with IV and SC vedolizumab
• Persistence of SC vedolizumab at month 12 in patients previously treated by IV vedolizumab every 4 weeks, compared to patients treated by IV vedolizumab every 8 weeks
• Twelve-month cumulative surgery rates
• Hospitalization rate at month 12
• Cumulative infection rate at month 12
• Cumulative injection reactions at month 12
• Cumulative adverse events (AEs) rate at month 12
• Comparison between incidence of specific anti-drug antibodies and incidence of AEs

Inclusion Criteria:

• Male or female subjects who are more than 18 years of age, on the day of signing informed consent

• Documented diagnosis of IBD, established on the basis of standard clinical, endoscopic and/or histological criteria.

• CD or UC remission defined per clinical assessment as a Harvey Bradshaw Index (HBI) score ≤4 for CD patients and a Partial Mayo Score (PMS) < 2 with each sub-score of 1 or less for UC and/or according to ECCO classification within previous 3 months

• Currently treated with IV vedolizumab

• Patients agreeing to switch from IV to SC formulation

• Receiving or not the concomitant following drugs (but must remain on stable dose for 12 weeks):

  • Oral 5-aminosalicylates (5ASA) compounds or rectal formulations of 5ASA provided the dose to be stable at least 4 weeks before switching
  • Azathioprine, 6-Mercaptopurine or methotrexate provided the dose has been stable for 4 weeks prior to inclusion • Each patient is required to provide written informed consent in order to be included in the study

Exclusion Criteria:

• Current use of adalimumab, infliximab, golimumab or ustekinumab
• Current use of JAK inhibitors or S1P modulators
• Current use of steroids or within the last three months for IBD
• Treatment with any investigational agent in the past 30 days or five half-lives prior to the screening visit (whichever is longer)
• Active clinically significant infection or HIV, Hep B, Hep C, untreated tuberculosis
• Female subjects with pregnancy or breastfeeding

Age ≥ 18 years old, CD patients (HBI ≤ 4) or UC patients (PMS ≤ 2) with established diagnosis > 6 months treated with vedolizumab IV, agreeing to switch from IV to SC formulation or who have just switched to subcutaneous vedolizumab as part of routine care