The Efficacy and Safety of Combining Probiotic VSL#3 With Vedolizumab for the Treatment of Moderate Ulcerative Colitis

An imbalance in the gut microbiota and mucosal immune dysfunction leading to intestinal inflammation are central to the pathogenesis of ulcerative colitis (UC). Both international and domestic inflammatory bowel disease (IBD) guidelines consistently recommend the use of the probiotic VSL#3 for inducing or maintaining remission in cases of mild-to-moderate UC. While the development of biologic therapies in recent years has provided new directions for IBD treatment, classic biologics such as infliximab may increase the risk of opportunistic infections and malignancies. Vedolizumab, when used for the induction therapy of UC, has a response rate of less than 80%, a slightly slower onset of action, and a slight increase in Clostridioides difficile infection (CDI) incidence. Currently, there is a lack of clinical data on the adjunctive use of VSL#3 with biologic agents in the treatment of UC globally. Therefore, this project aims to design a multi-center, randomized, placebo-controlled, double-blind study. The primary objective is to compare the changes in clinical response in patients with moderately active UC treated with either VSL#3 or placebo in combination with vedolizumab (VDZ) for six weeks.