Better tumor immune microenvironment in patients with older lung adenocarcinoma.

e20544 Background: Lung adenocarcinomas (LUAD) is the most common histological subtype of lung cancers. Immunotherapies (ICIs) have been confirmed to improve the clinical outcomes of LUAD patients. Efficacies of ICIs are considered strongly associated with tumor immune microenvironments (TIME). Age-related immune dysfunction might induce difference on the efficacy of ICIs between younger and older patients. However, the potential effect of age on TIME remains little known and controversial. Herein, we aimed to analysis the association between age and TIME based on The Cancer Genome Atlas (TCGA) database. Methods: We screened out 582 LUAD patients with complete information, whose tumors underwent next-generation sequencing (NGS) detection in TCGA. All patients were divided into two groups according to age, the younger group (age < 50-year old) and the older group (age≥50-year old). The differences of immune-related signatures between the two groups were calculated according to previous reports. We also analyzed the differences in immune-related signature between different clinical stages. P-values were calculated via the T.Test. Results: In total 582 patients with LUAD in our study, 115 (19.76%) patients in younger group and 467 (80.24%) patients in older group were found. Many immune-related signatures were found significantly higher in older group than in younger group, including cytolytic activity (CYT) (p = 0.0352), expanded immune signature (p = 0.0065), T cell inflamed gene expression profile (GEP) (p = 0.0048), IFN-γ-related response genes (p = 0.0346), immune signature (p = 0.0022), immunosuppression (p = 0.0065), major histocompatibility complex class I (MHC class I) (p = 0.0319), T-cell survival (p = 0.0235), tertiary lymphoid structures (TLS) signature (p = 0.0001) and total_TILs_scores (p = 0.0020). In addition, tertiary lymphoid structure (p = 0.0355) and TLS_signature (p = 0.0243) were found significantly difference in different clinical staging, which decreased as the staging get later. On the contrary, cell cycle score (p = 0.0001) increased as the staging get later. Conclusions: Our study evaluated the impact of age and clinical stage on the TIME in patients with LUAD using a threshold of 50 years old for the first time. We founded that LUAD patients in older group had better TIME than in younger group and some immune-related signatures were significantly related with clinical staging.