Are severe immune-related adverse events more likely in patients with pre-existing autoimmune disease?

Abstract

e14599 Background: Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that activate the immune system to treat malignancy. As a consequence of this activation, ICIs may cause autoimmunity in healthy tissues, termed “immune-related Adverse Events” (irAEs). The literature reports a wide range in irAE incidence (10-80%), with a higher incidence in patients exposed to combination therapy. ICI treatment of patients with pre-existing autoimmune disease presents a dilemma for oncologists because of concern that immune activation will lead to more frequent or severe irAEs. As a result, these patients have been excluded from ICI clinical trials. Prior studies suggested that approximately 40% of patients with pre-existing autoimmune disease experience an autoimmune exacerbation during ICI treatment, but more data are needed on the incidence and severity of irAEs in other tissues. Methods: This retrospective case-control study included adult patients who received an FDA-approved ICI for treatment of a solid malignancy (excluding non-melanoma skin cancer) from 2015-2021 at an academic medical center. Cases were patients with pre-existing autoimmune disease. Controls without pre-existing autoimmunity were matched 2:1 based on age, sex, ICI class, and cancer type. Severe IrAEs were defined as grade three or higher by CTCAE definitions and occurring after ICI exposure. ICD-9 and 10 codes were used to identify patients with subsequent data extraction by manual chart review. Results: Of 3,130 adult cancer patients treated with ICIs, 28 cases were identified with pre-existing autoimmune disease: antiphospholipid syndrome (n=1), inflammatory polyarthritis (n=3), juvenile arthritis (n=1), multiple sclerosis (n=3), psoriatic arthritis (n=3), rheumatoid arthritis (n=14), and type I diabetes (n=3). Six out of 28 cases (21.4%) developed severe irAEs, including three (50%) who received anti-PD1/PDL1 monotherapy and three (50%) who received ICI combination therapy. One case experienced a grade five irAE (death) attributed to ICI-colitis; the remaining five patients (83.3%) successfully recovered with suspension of ICI therapy and treatment with immunosuppressive medications. By comparison, 9/56 (16.1%) controls developed severe irAEs. The odds of developing a severe irAE were not significantly different in patients with pre-existing autoimmunity compared to controls (OR 1.42, 95% CI 0.42-4.68, p=ns). Subgroup analysis of 23 cases and 46 controls treated with anti-PD1/PDL1 monotherapy also found no difference in the odds of severe irAE development (OR 0.84, 0.22-3.70, p=ns). Conclusions: Our data suggest that the majority of solid tumor patients with pre-existing autoimmune disease can safely receive ICI monotherapy and combination therapy. Severe (grade 3 or higher) irAEs were infrequent, often treatable, and did not occur more frequently than in patients without pre-existing autoimmunity.