Wu Lee, Y.-H.; Chang, P.-C.; Yan, Z.-C.; Hong, Y.-C.; Yu, K.-T.; Hu, T.-Y.; Wu, P.-S.; Lin, C.-C.; Ko, T.-M.; Yang, J.-M.; Yang, M.-H.; Wu, C.-Y.; Lin, J.-C.

Background Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy by restoring anti-tumor immunity. However, persistent antigen exposure drives T cell exhaustion, limiting the effectiveness of ICIs. Ignorant T cells are antigen-specific T cells that maintain a naive state by regaining stem-like properties, allowing them to remain fully responsive to subsequent immunization. Virus-related hepatocellular carcinoma (HCC) demonstrates superior responses to ICIs compared to non-viral HCC, prompting us to investigate whether immunologically ignorant T cells exist in HBV-associated HCC and represent a promising target for improving immunotherapy outcomes. Methods Single-cell RNA sequencing (scRNA-seq) was performed on tumor tissues from patients with HBV-associated HCC. For validation, immunostaining was conducted on the discovery cohort and an independent cohort of 16 non-B non-C HCC and 22 HBV HCC. The enrichment of TIGIT and NECTIN3 in the proposed ignorant T cell was further validated using the TCGA database. Results scRNA-seq identified distinct HBV-infected HCC populations and revealed NECTIN3 upregulation in HBV-enriched subsets. CellChat analysis uncovered a novel NECTIN3-TIGIT tumor-immune interaction in HBV-enriched subsets, which shifted toward TIGIT-NECTIN2 as viral transcription declines. Trajectory analysis revealed the emergence of ignorant CD8 T cells following T cell exhaustion. TIGIT-NECTIN2/3 interactions deliver a weak exhaustion signal. This allows T cells to survive and regain naive-like properties as ignorant cells. Integration of bulk RNA-seq data identified CD24, STMN1, and EZH2 as potential biomarkers of ignorant CD8 T cells. Conclusions TIGIT-NECTIN2/3 interactions present a promising axis for preserving immunologically ignorant T cells and sustaining ICI responsiveness in HBV-associated HCC.