Background/Objectives: Immune aging has been associated with survival outcomes in patients with lung adenocarcinoma (LUAD), but its relevance within the tumor microenvironment (TME) remains unclear. Methods: Clinical, RNA-sequencing, and somatic mutation data from the TCGA LUAD cohort were analyzed. Immune aging score within the TME was quantified using a predefined blood-driven 121-gene immune aging signature (IAS-121), and patients were categorized into the lowest versus the highest IAS-121 tertiles. Immune cell composition in the TME was inferred using xCell. Overall survival (OS) was evaluated using Kaplan–Meier analysis, Cox proportional hazards models adjusted for age, sex, tumor stage, smoking status, and EGFR mutation status, and restricted cubic spline analysis to examine the dose–response relationship between IAS-121 and mortality risk. Sensitivity analyses comparing the highest versus lowest quartiles or higher than median versus lower than median of IAS-121 were performed. Two independent LUAD cohorts (GSE68465 and GSE50081) were employed for validation. Results: A total of 518 patients with LUAD from the TCGA cohort were analyzed. Restricted cubic spline analysis showed a linear association between IAS-121 and OS. Patients in the highest IAS-121 tertile showed significantly better survival than those in the lowest tertile in both the TCGA cohort (p < 0.001) and the external validation cohorts (p = 0.003). In multivariable-adjusted Cox models, the lowest IAS-121 tertile was associated with worse survival in TCGA (adjusted HR 1.87, 95% CI 1.20–2.92) and in the pooled external cohorts (adjusted HR 1.57, 95% CI 1.02–2.43). Subgroup analyses showed generally consistent associations across clinical strata. Tumors with higher IAS-121 exhibited lower CD8+ and CD4+ naïve T-cell enrichment but higher neutrophil infiltration. Conclusions: Immune aging within TME is associated with poorer survival in LUAD. Given this study is hypothesis-generating, further investigations integrating tissue- and blood-based measures of immune aging are warranted to clarify its clinical and biological implications.
Kim et al. (Thu,) studied this question.