Abstract 799: Comparing the efficacy of infliximab and vedolizumab in treating steroid-refractory immune checkpoint inhibitor-induced colitis

Abstract Purpose: This study aims to evaluate the efficacy of infliximab and vedolizumab in managing corticosteroid-refractory immune checkpoint inhibitor (ICI)-induced colitis. Some patients receiving immunotherapies develop severe, grade 3+ ICI-induced colitis, which often requires second-line treatments such as biologics commonly used for irritable bowel disease. Although there is literature supporting the use of infliximab, limited data exist regarding the efficacy and specific use of vedolizumab for ICI-induced colitis. Methods: A retrospective analysis was conducted on patients treated with either vedolizumab or infliximab alongside a checkpoint inhibitor over the past five years (March 1, 2019 - March 1, 2024). Patients included were treated with vedolizumab and received one of the following immunotherapies at UC San Diego: pembrolizumab, nivolumab, ipilimumab, atezolizumab, durvalumab, or cemiplimab. Patients treated with infliximab/vedolizumab for other indications, such as conventional irritable bowel syndrome, were excluded. Results: The database search identified 16 patients on infliximab and 18 on vedolizumab. The final analysis included 9 patients in the infliximab group and 8 in the vedolizumab group. Most patients were white and had various types of cancer, predominantly at advanced stages (III or IV). Of the patients, 41% were receiving PD1-targeted immunotherapy at the onset of colitis symptoms. Patients received an average of 1.7 doses of infliximab (range: 1-8) and 3.5 doses of vedolizumab (range: 1-8). Among infliximab-treated patients, 66% received a single dose during hospitalization without further treatment, compared to 12.5% of vedolizumab-treated patients. Infliximab enabled 66% of patients to successfully complete a steroid taper, while vedolizumab had a success rate of 75% (Chi-square, p = 0.70). The average time on steroids was longer in the vedolizumab group (30.21 weeks) than in the infliximab group (17.97 weeks), though this difference was not statistically significant (p = 0.80). No significant differences were observed when results were stratified by sex (infliximab, p = 0.40; vedolizumab, p = 0.21) or type of immunotherapy (infliximab, p = 0.96; vedolizumab, p = 0.21). Conclusion: Both infliximab and vedolizumab appear to be viable options for treating ICI-induced colitis, with most patients successfully completing a steroid taper. However, this study does not provide sufficient evidence of superior outcomes for either drug, although some patients responded well to treatment. Therefore, infliximab remains a reasonable first-line treatment for steroid-refractory ICI-induced colitis. Citation Format: Irene Li, Sandip P. Patel. Comparing the efficacy of infliximab and vedolizumab in treating steroid-refractory immune checkpoint inhibitor-induced colitis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 799.