The CD4+ T cell population partners with Tpex CD8+ T cells to mediate antitumor immunity in the tumor microenvironment

CD4⁺ T cells support the priming, expansion, and function of CD8⁺ T cells through 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 primarily from lung cancer patients and, in part, renal cell carcinoma. We identify an IL-7Rhigh CCR6⁺ Th1-like CD4⁺ T cell-population, named Th7R, that is numerically and spatially partnered with Tpex. Th7R cells express lymphotoxin-β and CXCL13, correlate with high endothelial venules, and co-localize with Tpex in tertiary lymphoid structures. 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. Intratumoral Th7R and Tpex associate with improved response to neoadjuvant PD-1 blockade therapy. These results suggest that Th7R cells act as partners of Tpex to sustain antitumor T-cell immunity. CD4 + T cells support the clonal proliferation and cytotoxic activity of CD8 T cells. However, the precise identity of this CD4+ t cell cluster remains elusive. Here, by performing single-cell transcriptomics and mass cytometry analysis of patient-derived samples, the authors identify Th7R cells as a CD4 T cell population that supports the precursor exhausted CD8 + T cells-mediated antitumor immunity and the association between these cells as a good predictor of immunotherapy response.