Association of immune-related adverse events with survival in patients receiving immune checkpoint inhibitor plus chemotherapy for lung cancer

The association of immune-related adverse events (irAEs) and baseline peripheral blood count ratios with the effectiveness of immune checkpoint inhibitor (ICI) plus chemotherapy in patients with non-small cell lung cancer (NSCLC) remains unclear. This multicenter, retrospective study analyzed data from 191 patients treated with pembrolizumab or atezolizumab plus chemotherapy as first-line therapy across five hospitals in Japan between December 2018 and March 2021. Progression-free survival (PFS) and overall survival (OS) were assessed in relation to irAEs within a 6-week landmark analysis and baseline peripheral blood count ratios using Cox proportional hazards models. IrAEs occurred in 70 patients (36.6%) and showed no substantial association with survival (PFS: hazard ratio [HR] = 1.04, 95% confidence interval [CI] = 0.70–1.53 and OS: HR = 0.82, 95% CI = 0.49–1.34). Conversely, baseline peripheral blood count ratios were considerably linked to survival. A higher neutrophil-to-lymphocyte ratio correlated with reduced PFS (adjusted HR = 1.62, 95% CI = 1.10–2.40) and OS (adjusted HR = 2.50, 95% CI = 1.53–4.09), with similar trends for the lymphocyte-to-monocyte and platelet-to-lymphocyte ratios. Collectively, these findings suggest that although irAEs were not predictive of survival, baseline blood count ratios can serve as prognostic biomarkers in patients with NSCLC receiving chemoimmunotherapy.