Characterization of the immune cell infiltration landscape in lung adenocarcinoma

Immune checkpoint inhibitors (ICIs) have played an important role in the treatment of lung adenocarcinoma (LUAD). However, their effectiveness is limited, and many patients exhibit a weak response. In this study, we propose a new and more effective immunophenotyping method for evaluating the prognosis and tumor microenvironment (TME) cellular infiltration characteristics in LUAD patients and their response to immunotherapy. Based on the transcriptomic and prognostic data of 584 patients with LUAD collected from TCGA cohort and GEO dataset, we combined tumor immune infiltration, the TME, and immune-related genes to score each sample using principal component analysis (PCA) and divided the patients into two subgroups with high and low tumor immune infiltration (TII) scores. The high-TII score group was characterized by increased immune activation and apoptosis signaling pathways. Moreover, clinical subgroup analysis demonstrated that the TII immune score was also applicable to different clinical groups and the high-TII score group still exhibited good prognosis and better response to ICIs. This study mapped the TII landscape in LUAD patients and confirmed that the TII score is helpful for predicting patient response to immunotherapy and may guide more effective immunotherapeutic strategies.