CXCR4 orchestrates the TOX-programmed exhausted phenotype of CD8+ T cells via JAK2/STAT3 pathway.

Evidence from clinical trials suggests that CXCR4 antagonists enhance immunotherapy effectiveness in several cancers. However, the specific mechanisms through which CXCR4 contributes to immune cell phenotypes are not fully understood. Here, we employed single-cell transcriptomic analysis and identified CXCR4 as a marker gene in T cells, with CD8⁺PD-1^high exhausted T (T_ex) cells exhibiting high CXCR4 expression. By blocking CXCR4, the T_ex phenotype was attenuated in vivo. Mechanistically, CXCR4-blocking T cells mitigated the T_ex phenotype by regulating the JAK2-STAT3 pathway. Single-cell RNA/TCR/ATAC-seq confirmed that Cxcr4-deficient CD8⁺ T cells epigenetically mitigated the transition from functional to exhausted phenotypes. Notably, clinical sample analysis revealed that CXCR4⁺CD8⁺ T cells showed higher expression in patients with a non-complete pathological response. Collectively, these findings demonstrate the mechanism by which CXCR4 orchestrates CD8⁺ T_ex cells and provide a rationale for combining CXCR4 antagonists with immunotherapy in clinical trials.