Abstract / Summary
ABSTRACT CD8 + T cells are central mediators of antitumor immunity, and their functional heterogeneity profoundly influences immunotherapy efficacy. We characterized the spatial distribution of CD8 + T cell subsets stratified by PD‐1 expression within the tumor microenvironment (TME) of non‐small cell lung cancer (NSCLC). Our analyses revealed that PD‐1 + CD8 + T cells were more prevalent in the non‐central regions than in the tumor core, and higher abundance of these cells in the non‐central zone was associated with poorer response to PD‐1 blockade. Enrichment of PD‐1 + CD8 + T cells diminished cancer cell apoptosis induced by anti‐PD‐1 mAb treatment in an in vitro co‐culture system modeling in vivo conditions. The PD‐1 + CD8 + T cell subset exhibited significantly reduced clonal diversity, as determined by TCR Vβ repertoire analysis, single‐cell T cell receptor sequencing (scTCR‐seq), and GLIPH2 clustering, along with impaired effector functions and distinct transcriptional programming. Mechanistically, IL‐6 produced dominantly by non‐central tumoral BTLA + B cells promoted PD‐1 expression on CD8 + T cells, mirroring the spatial pattern in tumoral PD‐1 + CD8 + T cells. Our data further identify a spatially organized functional unit comprising PD‐1 + CD8 + T cells and neighboring BTLA + B cells within the non‐central tumor region. This specialized niche, defined by anatomical localization, functional state, TCR repertoire, and intercellular crosstalk, contributes to the establishment of resistance to immune checkpoint blockade.