Risk factors for immune-related adverse events associated with pembrolizumab in patients with solid tumors

Despite the widespread use of pembrolizumab, few real-world studies investigated risk factors for immune-related adverse events (irAEs). This study aimed to evaluate risk factors for irAEs associated with pembrolizumab treatment in patients with solid tumors.

This retrospective single-center study included adult patients with solid tumors treated with pembrolizumab at King Hussein Cancer Center between January 2020 and June 2024. Patients' demographic, clinical, and laboratory data at baseline and after 1 month of pembrolizumab initiation, were collected. Multivariate logistic regression analysis was used to identify risk factors for irAEs at baseline and after 1 month of pembrolizumab therapy.

During the study period, 978 patients were included, with a median age of 60 years (range, 20-86 years). IrAEs occurred in 31.9% of patients, among whom lung cancer was the most common cancer type (46.5%). In the multivariate logistic regression analysis, baseline neutrophil-to-lymphocyte ratio (NLR) < 3 (odd ratio (OR) 1.58, p = 0.046) and higher programmed death-ligand 1 (PD-L1) expression (OR 1.009, p = 0.006) were identified as independent risk factors for irAEs. Elevated PD-L1 expression (OR 1.007, p = 0.028), and hemoglobin ≥ 10 g/dL (OR 1.90, p = 0.021) were identified as independent risk factors for irAEs after 1 month of pembrolizumab therapy.

One-third of patients developed irAEs. An NLR < 3, higher PD-L1 expression, and hemoglobin ≥ 10 g/dL were identified as risk factors for irAEs. These factors may help in early risk stratification of patients receiving pembrolizumab.