Kinnosuke Matsumoto, Yoshimi Noda, Kensuke Hachiya, Fumitaka Muramatsu, Naoki Okamoto, Weizhen Jia, T Shiroyama, Masahide Mori, M. Tamiya, Yuhei Kinehara, A. Tamiya, Shigeki Shimizu, Hidekazu Suzuki, Kiyonobu Ueno, Toshie Niki, Satoshi Tetsumoto, Osamu Morimura, Akio Osa, Toshiyuki Minami, Satoshi Nojima, Yoshito Takeda, Yasushi Shintani, A. Kumanogoh, Nobuyuki Takakura
BACKGROUND: Tertiary lymphoid structures (TLSs) maturity and cellular composition shape resistance or sensitivity to immune-checkpoint blockade (ICB) across cancers. Single-cell spatial resolution data for the endothelial compartment of TLSs are lacking; therefore, we investigated the cellular composition, endothelial dynamics, and cell-cell interactions within TLS regions. METHODS: We applied high-resolution Xenium In Situ spatial transcriptomics to eight samples collected from non-small-cell lung cancers (NSCLC) (four after chemoimmunotherapy, four untreated), extracted 90 TLS regions, generated approximately 320,000 single-cell profiles from those regions, and analyzed the endothelial compartment within each TLS. We independently assessed the exploratory findings using multiplex immunofluorescence and survival analysis in a separate cohort of 45 patients receiving immunotherapy. RESULTS: Spatial mapping revealed a reproducible, B-cell-dominant TLS architecture across all samples. Mature TLSs contained CXCL13-rich follicular cores and were associated with a favorable prognosis. Within the endothelial compartment, high endothelial cells (HECs) forming high-endothelial venules (HEVs) segregated from other endothelial cells; in mature TLSs these HECs exhibited high inhibitor of DNA binding 1 (ID1) expression and an adhesion molecular signature, promoting lymphocyte recruitment. Patients with tumors harboring ID1-high HEVs showed higher response rates and pronounced survival advantage; multivariable analysis confirmed ID1-high status as an independent prognostic factor. Conversely, ICB exposure eventually reduced ID1 expression and adhesion molecule levels in HECs, impaired lymphocyte trafficking, and promoted a shift toward a remodeled endothelial state. CONCLUSIONS: ID1expression, linked to HEC differentiation during TLS maturation or ICB exposure, marks a functionally mature, lymphocyte-recruiting HEV that predict durable response to immunotherapy. These findings provide a novel mechanistic framework and practical biomarkers for HEV-centered immuno-oncology strategies in NSCLC.