The Cd4+ T cell population Partners with Tpex CD8 T cells to mediate Antitumor Immunity in the Tumor Microenvironment. [P6]

The priming, expansion, and function of CD8⁺ T cells are helped by CD4⁺ T cells via dendritic cells. Precursor exhausted T cells (Tpex) maintain self-renewal and supply cytotoxic CD8⁺ T cells in the tumor microenvironment (TME), but the identity of their CD4⁺ T-cell partners remains unclear. Here, we perform scRNA-seq, scTCR-seq, and mass cytometry analysis on peripheral blood, tumor, and lymph nodes derived from lung cancer patients and identify a population of IL-7Rhigh CCR6⁺ Th1-like CD4⁺ T cells, namedTh7R, that is numerically and spatially partnered with Tpex cells. Th7R cells express lymphotoxin-β and CXCL13, correlate with high endothelial venules, and co-localize with Tpex in tertiary lymphoid structures. Furthermore, Th7R cell abundance correlates with Tpex numbers in the TME and lymph nodes, and adoptive transfer of Th7R increases Tpex in a preclinical mouse model of skin cancer. In lung cancer patients, Th7R and Tpex in TME are associated with better response to neoadjuvant PD-1 blockade therapy. Thus, these results suggest that Th7R cells act as partners of Tpex CD8 T cells to sustain antitumor T-cell immunity.