Immune checkpoint inhibitors in patients with rheumatoid arthritis: a matched cohort study of immune-related adverse events and survival

Patients with pre-existing rheumatoid arthritis (RA) are increasingly treated with immune checkpoint inhibitors (ICIs), but RA-specific evidence on immune-related adverse events (irAEs) and survival remains limited because autoimmune disease patients were largely excluded from pivotal trials. We aimed to evaluate the risk of irAEs and overall survival (OS) in patients with pre-existing RA initiating ICIs compared with matched non-RA controls. We conducted a nationwide matched cohort study using the National Health Information Database (NHID) of the National Health Insurance Service (NHIS). Patients with RA initiating ICIs (2018–2022) were matched (1:4) to non-RA controls by age, sex, Charlson Comorbidity Index, index year, and cancer type. irAEs were defined as events requiring systemic corticosteroids with ICI interruption or discontinuation. Incidence rate ratios (IRRs) of irAEs and hazard ratios (HRs) for OS were estimated using Cox models, with cancer-specific subgroup analyses. Among 17,971 ICI-treated cancer patients, 759 with RA and 2647 matched patients without RA were included. The incidence of irAEs was comparable between groups (IRR 0.92, 95% CI 0.79–1.07), and OS did not differ (adjusted HR [aHR] 0.95, 95% CI 0.86–1.05). In cancer-specific analyses, RA was associated with improved survival in renal/urinary tract cancers (aHR 0.72, 95% CI 0.55–0.94) but not in other cancer types. Pre-existing RA was not associated with increased irAE risk or worse survival in patients treated with ICIs. These findings provide real-world evidence supporting the use of ICIs in patients with RA, although heterogeneity across cancer types warrants further investigation.