Risk of severe immune-related adverse events in cancer patients with pre-existing autoimmunity receiving immune checkpoint inhibitor therapy

Introduction: Immune checkpoint inhibitors (ICI) are widely used cancer therapies that harness the immune system to target malignant cells but subsequently can cause serious off-target immune-related Adverse Effects (irAEs). Patients with pre-existing autoimmune disease have historically been excluded from ICI clinical trials due to scientific concerns over increased risk of irAEs and flares of underlying autoimmune disease.Methods: We designed a retrospective, single-center, case-control study at a large, academic medical center to evaluate the incidence and severity of irAEs in patients with pre-existing autoimmunity compared to controls. Controls were matched 2:1 for age, sex, cancer histology, and ICI class. Patients were identified with ICD 9 and 10 codes followed by manual chart extraction. Cases were defined as patients with pre-existing, systemic autoimmunity. The primary outcome was severe irAE (Grade 3 or higher by Common Terminology Criteria for Adverse Events) within 6 months of ICI therapy. Secondary outcomes included response to ICIs, resolution of the irAE, ICI rechallenge success, and survival. Statistical analyses were performed by Chi-square, Fishers exact, Mann-Whitney, and Log-rank tests.Results: Of 3,130 patients treated with ICIs from 2015-2021, 28 cases with pre-existing autoimmune disease were identified and were matched with 56 controls. Pre-existing autoimmune conditions included antiphospholipid syndrome, inflammatory polyarthritis, juvenile rheumatoid arthritis, multiple sclerosis, psoriatic arthritis, rheumatoid arthritis, and type I diabetes. Multiple cancer histologies, including genitourinary, gynecologic, head & neck, hepatobiliary, lung, melanoma, and pancreatic, were represented. Six of 28 cases (21.4%) experienced severe irAEs compared to 9/56 (16.1%) controls; the odds of developing a severe irAE were not significantly different (OR 0.43, 95% CI 0.083-2.33, p = 0.627, ns). Moreover, there were no significant differences in overall survival or tumor response between the two groups. The majority of irAEs resolved without long-term sequelae (66.7% of cases, 55.6% of controls). The majority of patients who were rechallenged with ICIs were successful in continuing therapy (66.7% of cases, 100% of controls).Conclusion: Our study suggests that patients with pre-existing autoimmune disease can be treated with ICI cancer therapies and experience rates of severe irAEs and overall survival that are similar to those of the general population. These data can aid oncologists in discussing risks and benefits of ICIs when treating patients with pre-existing autoimmunity and solid tumors.