Racial differences in development of immune-related adverse events.

Abstract

e15148 Background: Immune-related adverse events (irAEs) due to immune checkpoint inhibitors (ICIs) are caused by non-specific immune system activation and develop in 30-70% of patients. The goal of this study is to examine the association of race with the development of irAEs secondary to ICIs as autoimmune diseases generally exhibit racial differences. Methods: A retrospective chart review was done using University of Louisville pharmacy database. Patients with solid cancers who received ICIs between Jan 2016 to June 2019 were included. IrAEs were identified through the review of electronic medical records. Descriptive analysis evaluated the incidence and severity of irAEs. Multivariable logistic regression was used to calculate standardized incidence of irAEs among Whites and African Americans. Results: A total of 476 patients were included in this study. The mean age was 61 years, 57% were males and 89.7% were whites. A majority of patients had melanoma (50%). The remainder of the dataset included lung (33.4%), gastrointestinal (7.4%), head & neck (4.8%), breast (2.5%) and genitourinary (1.9%) cancers. ICIs included single agent anti-PD-1 (74.8%), single agent anti-PD-L1 (9.4%), combination anti-CTLA-4 with anti-PD-1 (7.1%). Some patients were also treated with > 1 ICI as subsequent therapy (8.6%). Overall, the rate of irAEs was 44.3% with 33.8% grade 1-2 and 12.4% grade 3-4 irAEs. There was no difference in development of any grade irAEs in Whites as compared to African Americans after adjusting for age, sex, cancer type and ICIs (44.3% vs 44.2%; OR: 0.99, 95% CI: 0.50 – 1.97; p = 0.99). There was also no difference in development of grade 3-4 irAEs in whites as compared to African Americans (12.8% vs 14.5%; OR: 1.16, 95% CI: 0.43 – 3.12; p = 0.75). Conclusions: In this study, we found no racial difference in the development of irAEs between Whites and African Americans. This is in contrast to general autoimmune diseases which exhibit racial differences with higher prevalence among African Americans compared to Whites. We will continue to accrue patients to this study as larger sample size is needed to confirm these findings.