Disease outcomes in immune checkpoint inhibitor colitis: A study comparing initial endoscopic and histological presentation and treatment options.

Abstract

e24083 Background: Immune-mediated diarrhea and colitis (IMDC) is a common toxicity to immune checkpoint inhibition (ICI) that is becoming increasingly common. Studies exploring the clinical course and outcomes of IMDC have been limited to relative small sample sizes ( < 200). We therefore aimed to provide a comprehensive account of the clinical, endoscopic, and histologic features of IMDC as well as the efficacy of IMDC treatment in a representative sample. Methods: This was a single-center retrospective study of all patients who received ICIs between January 2010 to February 2024 and developed IMDC. Detailed information was collected from the electronic health record regarding patient demographics, and IMDC stool biomarkers, endoscopic and histologic reports, clinical symptoms and treatment, and outcomes such as clinical symptom resolution, hospitalization, and mortality. SPSS 26.0 was used for data analysis. Results: A total of 1,151 patients were included. Patients commonly presented with diarrhea (98.3%) or abdominal pain (38.6%). Selective immunosuppressive therapy was needed in around 40% of patients, and 85% of patients were able to achieve symptom resolution. Around 40% had non-ulcerative inflammation and 23% had ulcerative inflammation, with 37% having normal macroscopic findings. Around 60% of patients had acute histological inflammation, 28% with chronic inflammation, and 11.7% with microscopic inflammation. Infliximab was associated with shorter time to clinical response and in fewer doses than vedolizumab with equal efficacy between the two medications. Conclusions: Our study is the largest to date exploring the various manifestations of IMDC as well as its treatment and outcomes. We found that its features overlap with different inflammatory colitides. Infliximab and vedolizumab are equally effective at achieving symptom remission, although infliximab has a shorter time to response. As more patients develop IMDC, larger scale studies can be carried out to validate these results.