HBV-driven expansion of CXCR6⁺-exhausted T cells and CXCL16⁺ macrophage interaction: Implications for immunotherapy...

Hepatitis B virus (HBV) may alter immunotherapy responsiveness in HBV-positive hepatocellular carcinoma (HCC) patients. However, the underlying immune mechanisms remain unclear. To characterize the immune determinants underlying the enhanced immunotherapy response observed in HBV⁺ HCC patients, we comprehensively analyzed 528 HCC patients who received immunotherapy, encompassing diverse hepatitis infections. We performed an analysis incorporating single-cell RNA sequencing, spatial transcriptomics, and tissue microarray validation to map the tumor immune landscape. An adoptive T cell transfer combined with anti-programmed death-1 (PD-1) therapy in a syngeneic HCC mouse model was performed to validate key findings. HBV⁺ HCC patients exhibited superior responses to immunotherapy and prolonged overall survival. Remarkably, HBV⁺ HCC patients harbored an elevated proportion of exhausted CD8⁺ T cells, and these cells concurrently exhibited enhanced immune activity and cytotoxic potential. Our study spotlighted a novel subset of exhausted CD8⁺ T cells, termed PD-1⁺ CXCR6⁺ CD8⁺ T cells. In untreated cases, high levels of PD-1⁺ CXCR6⁺ CD8⁺ T cells correlated with poor prognosis. In contrast, among patients receiving immunotherapy, their enrichment was associated with markedly better outcomes. In vivo, adoptive transfer of CXCR6⁺ T cells markedly augmented the antitumor efficacy of anti-PD-1 therapy. Moreover, PD-1⁺ CXCR6⁺ CD8⁺ T cells demonstrated a prominent interaction with CXCL16⁺ macrophages in HBV⁺ HCC. Taken together, we identified a novel exhausted T cell subset, PD-1⁺ CXCR6⁺ CD8⁺ T cells, that are enriched in HBV⁺ HCC patients and maintained by CXCL16⁺ macrophages. The enrichment of PD-1⁺ CXCR6⁺ CD8⁺ T cells and their interaction with CXCL16⁺ macrophages may contribute to the enhanced immunotherapy response observed in HBV⁺ HCC.