Title: Characterizing institutional uses of vedolizumab for immune checkpoint inhibitor (ICI) colitis Authors: Amrit Pabla, PharmD; Christopher Wang, PharmD, BCOP; Lina Shao, PharmD, BCOP; Aliyah Pabani MD, MPH; Joanna Melia, MD; Vi Gilmore, PharmD, BCPS Abstract Objective: This study aims to characterize institutional prescribing patterns of vedolizumab prior to and after implementation of formulary restriction changes and evaluate its clinical outcomes among patients with ICI colitis at Johns Hopkins Medicine. Methods: This retrospective, single-health system study evaluated adult patients with ICI colitis that received vedolizumab from July 2024 to July 2025. Patients were included if they received at least one dose of ICI therapy, had a diagnosis of ICI colitis, and received at least one dose of vedolizumab. Patients were excluded if they were less than 18 years of age. The objectives of this study were to characterize the prescribing practices of vedolizumab for ICI colitis 6-months before and after implementation of formulary restriction changes in January 2025, report efficacy and safety outcomes of vedolizumab for ICI colitis and to characterize ICI rechallenges for patients who had resolution of their ICI colitis. Results: A total of 23 patients were included, of which 12 patients were in the pre- implementation cohort, and 11 were in the post- implementation cohort. The median age was 71 years old, 38% were female, and all patients were white. Most patients had melanoma (48%) and received combination ICI therapy (61%). Vedolizumab was prescribed first-line following steroids in 91% of patients. A second immunosuppressant agent was required in 17% of patients for refractory symptoms. Infections occurred in 35% of patients, with median time to first infection of 37 days. Readmission for recurrent ICI symptoms occurred in 13% of patients, and ICI rechallenges occurred in 30% of patients. All patients with a rechallenge had no recurrent symptoms. Conclusions: This study characterizes the institutional prescribing patterns of vedolizumab at a single center health system and adds to existing literature supporting the use of vedolizumab for steroid refractory ICI-colitis. Self-Assessment Question: (True/False) Vedolizumab is a non-steroidal immunosuppressant option for treating steroid refractory ICI induced colitis.
