Pos0123 Immune-Related Adverse Events in Patients With a Pre-Existing Autoimmune or Inflammatory Disease Treated With Immune Checkpoint Inhibitors: A Nationwide Database Cohort Study

Background: In about 10% of patients, the immune response to immune check-point inhibitors (ICI) exceeds the anti-tumor response and leads to autoimmune complications (immune-related Adverse Events, irAEs), which can sometimes be severe and require the use of targeted therapies. Pre-existing autoimmune disease (AD) seems to increase the risk of irAE in patients treated with ICI. Objectives: To compare the prevalence and mortality of irAEs in patients with or without a pre-existing autoimmune or inflammatory disease. Methods: This retrospective study analyzed adults from the French nationwide healthcare information system ("système national des données de santé" SNDS) who initiated any immune checkpoint inhibitor (ICI) therapy for any cancer between 2016 and 2022. The aim was to investigate the occurrence of immune-related adverse events (irAEs) during ICI treatment and in the 12 months post-administration, comparing patients with and without a history of autoimmune disease. IrAEs were defined by the combination of (1) hospitalization for a cause evoking an irAE of any nature, and (2) either the initiation of corticosteroids, or of a conventional DMARD or a b/tsDMARD, or death. Propensity score matching was performed for patients with and without a pre-existing autoimmune or inflammatory disease. The propensity score included gender, age, type of cancer, type of ICI, time from cancer to initiation of ICI and from initiation of ICI to irAE, use of corticosteroids, hospitalization in intensive care unit, type of irAE, number of LTDs, Charlson's index and FDep social deprivation index. Overall survival was compared between the two groups using a Cox model. Results: 69,745 patients (men: 69.0%, mean age: 65.8 years) initiating an ICI were analysed. 5,252 (7.4%) patients had a pre-existing autoimmune or inflammatory disease, before initiation of ICI, notably including 594 patients with rheumatoid arthritis and 847 patients with inflammatory bowel disease. IrAE occurred in 568 patients (11%) in patients with a pre-existing autoimmune or inflammatory disease and 4374 patients (6.8%) without a pre-existing autoimmune or inflammatory disease, with a statistically significant increased risk (HR 3.07 (2.78-3.39)). Mortality was significantly increased in patients with a pre-existing autoimmune or inflammatory disease (HR 1.16 (1.1-1.22)). Conclusion: This extensive epidemiological nationwide study identified an increased risk of irAEs and a higher mortality in patients with a pre-existing autoimmune or inflammatory disease. Further investigations are needed to confirm and elucidate the determinants of these findings. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.