CD8+ T cells in tumors are heterogenous and exist in multiple differentiation states. Evidence has proposed CD39 as a marker of exhausted and tumor-reactive CD8+ T cells. Here, we analyzed a subset of tumor-infiltrating CD8+ T cells based on the expression of the immunosuppressive ATP ectonucleotidase CD39 and PD-1. Neoplasm-superficial biopsy and intratumoral EBUS-TBNA were used to assess the peripheral and central tumor microenvironment, respectively. CD39+CD8+ T cells dominantly accumulated in the peritumoral compartment of larger tumors and exhibited an exhausted phenotype compatible with PD-1 expression. Compared with CD39+CD8+ T cells, PD-1+CD39+CD8+ T cells are better biomarkers for predicting responses to anti-PD-1 therapy. Collectively, heterogenous distribution may be critical to elicit CD39 expression in lung cancer associated CD8+ T cells. Increased PD-1+CD39+CD8+ T cell levels within the peripheral TME can act as a candidate biomarker for lung cancer immunotherapy.

Malignant pleural effusions (MPE) are common in lung cancer, which were a complex microenvironment containing a plethora of immune and tumor signals. Gene alterations such as driver gene mutations were considered to affect the components in the TIME of NSCLC. Here, we demonstrated that pleural CD39+CD8+T cells were selectively elevated in firstly-diagnosed lung adenocarcinoma with wild-type EGFR compared to that in mutant EGFR, while abnormally more represented in MPE with epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) acquired resistance. Analysis showed that pleural CD39+CD8+T cells display exhausted phenotype and potential cytolytic function, together with skewed usages of T cell receptor (TCR)-Vβ repertoire in comparison with CD39-CD8+T cells, which constituted common feature of lung adenocarcinoma related MPE. Further study revealed TCR-Vβ diversity tended to be more enhanced in pleural CD39+CD8+T cell from MPE coupled with EGFR-TKI acquired resistance. Taken together, we have identified a subset of CD8+T cells expressing CD39 in MPE, whom proposed as the potential tumor-reactive CD8+T cells, and further provided a new understanding of dynamic immune composition of EGFR-mutant tumor microenvironment.