Abstract 5814: Immune-related adverse effects in patients with autoimmune disorders treated with immune checkpoint inhibitors

Abstract Background: Immune checkpoint inhibitors (ICI) have tremendously improved outcomes for various cancers but can be associated with immune-related adverse effects (IrAE), which can affect multiple organ systems. For patients with pre-existing autoimmune diseases (AD), there is an added risk of exacerbating autoimmunity, either through a flare of prior IrAEs or the development of de novo IrAEs during ICI therapy. Clinical trials leading up to FDA approval of ICIs excluded patients with pre-existing AD, resulting in a lack of data on the specific risks faced by this patient population. Our study aims to assess whether patients with pre-existing AD are more likely to develop IrAEs when treated with ICIs, and if so, whether these IrAEs are more severe. Methodology: We conducted a retrospective chart review of all patients diagnosed with AD and received ICIs for treatment of a solid tumor malignancy within the Geisinger Health System from January 1, 2017, to December 31, 2023. We analyzed the occurrence, subtype, and severity (grade) of IrAEs based on the Common Terminology Criteria for Adverse Events (CTCAE). Additionally, we assessed steroid use, treatment discontinuation, and hospitalization rates. Results: A total of 250 patient charts were identified using the cancer registry, 105 of them were excluded due to the absence of a pre-existing AD. Of the 145 patients with a pre-existing AD, 59 (40.7%) developed an IrAE, and 21 (14.5%) developed a severe (grade 3/4) IrAE. Additionally, 44 (30.3%) patients required steroids for the treatment of IrAE, and 12 (8.3%) were hospitalized due to an IrAE. The most prevalent IrAEs were colitis, rash, hypothyroidism, transaminitis, and pneumonitis, which occurred in 52 (35%) cases; of these, 13 (8.9%) were severe (grade ¾). Discussion: When comparing our results to those of previous studies, we found that the rates and severity of IrAEs were higher in patients with pre-existing AD compared to historical data on patients without AD. A meta-analysis by de Velasco et al. of 21 studies reported an IrAE incidence of 28% for all grades and 5% for grades 3 and 4. Similarly, Silverstein et al. analyzed 3,137 patients treated with ICIs and found that 3.8% were hospitalized due to IrAEs. These significant differences underscore the need for multidisciplinary collaboration and heightened monitoring for IrAEs in patients with AD. Citation Format: Aseel Saadeh, Pragosh Saini, Favour Nelson, Sumera Khan, Christian Adonizio, Ahmad Hanif. Immune-related adverse effects in patients with autoimmune disorders treated with immune checkpoint inhibitors [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 5814.