Background: Subcutaneous (sc) vedolizumab is an alternative to intravenous (iv) vedolizumab for the treatment of patients with mild-to-moderate flares of inflammatory bowel disease (IBD).

Objective: To analyse the persistence rate of the sc vedolizumab and its pharmacokinetics in patients previously treated with iv vedolizumab; describing clinical and biochemical remission rates at one year, and comparing previous intravenous intensification regimens.

Methods: Multicenter, descriptive, observational, and retrospective study of a cohort of 54 patients with IBD treated with iv vedolizumab for more than six months, who were switched to sc vedolizumab under a standard regimen, 32 patients (59%) with a diagnosis of ulcerative colitis (UC) and 22 patients (41%) with Crohn's disease (CD)

Results: After one year of follow-up, 93% of the patients continued with vedolizumab, 100% were in clinical remission, and 86% achieved biochemical remission (calprotectin <150). A progressive increase in vedolizumab levels was observed after switching to sc vedolizumab, with statistical significance (p<0.05). 14 patients (25.9%) were on an intensified regimen before switching to sc vedolizumab; however, all patients remained on subcutaneous vedolizumab at a dose of 108 mg every two weeks without the need for intensification.

Conclusions: After switching to sc vedolizumab in patients with endovenous vedolizumab treatment, high persistence rate at one year of follow-up is achieved, with a greater tendency to biochemical remission, which is more pronounced in previously intensified patients without the need for subcutaneous vedolizumab intensification.