Predictors of immune-related adverse events associated with checkpoint inhibitors.

Abstract

e15159 Background: Immune-related adverse events (irAE) remain a significant challenge with the expansion of checkpoint inhibitors (ICI) indications. Unlike previous studies published, we investigated risk factors for irAE development, including lymphocytes and neutrophils counts in lung cancer and melanoma treated with all available ICIs in current clinical practice. Methods: This is a retrospective study conducted at the University of South Alabama Mitchell Cancer Institute. Between 2015-2019. A total of 160 patients with a diagnosis of melanoma (N = 54) or lung cancer (N = 106) who received at least two doses of ICI including ipilimumab (15%), nivolumab (32%), pembrolizumab (35%), dual nivolumab/ipilimumab (5%), durvalumab (9%) and atezolizumab (4%). The patient's baseline characteristics were extracted with irAE (grade 3/4) details and survival outcomes. Descriptive statistics were used, Fisher exact test to compare categorical variables, and Wilcoxon rank sum test for continuous variables using JMP software. Results: The median age at diagnosis was 64 years (range 17-93), with 51% females. Race distribution with 76% Caucasians and 26% African Americans. Around 30% of the cohort was treated for recurrence, and 39% did receive prior systemic chemotherapy. Median overall survival (OS) was 13.5 months (m) for melanoma and 16 m for lung cancer with CI 95% [16-24] and [15-23], respectively. Twenty-nine (29%) percent of the cohort (N = 46) had grade 3/4 irAEs. Median of baseline hematological parameters including total white blood count (WBC), absolute neutrophil count (ANC), absolute lymphocyte count (ALC), ANC to ALC ratio, and platelet to ALC ratio of these patients were not statistically different from the cohort without grade 3/4 irAEs. Interestingly, if a patient has baseline ALC < 1K/μL, the risk of irAE recurrence is low when ICI is re-initiated, p = .0143 (after symptomatic recovery from irAEs). Conclusions: Irrespective of ICI used, baseline lymphocyte count, and its relation to other blood counts have no clear impact on irAE. Larger cohorts or prospective studies are needed to make stronger conclusions about the relationship between the immune system and the occurrence of irAEs