Twenty-year persistence of WT1-specific cytotoxic T lymphocytes in peritumoral brain tissue by peptide vaccine therapy: Transcriptomic evidence for resident memory T-cell induction.

Background: Sustained immune surveillance at tumor sites is considered essential for effective cancer immunotherapy; however, direct evidence of immune surveillance in humans is limited due to difficulty obtaining tumor and peritumoral tissues through invasive procedures. Methods: Peritumoral brain tissue was obtained during reoperation from a patient with Results: A high level of T-cell infiltration was observed in peritumoral brain tissue, despite the immune-privileged nature of the central nervous system. Notably, 38.4% of CD8 Conclusion: These findings provide in situ evidence of long-term persistence of WT1-specific CTLs in the human brain by continuous WT1 peptide vaccination. Such local immune surveillance may have contributed to the prevention of relapse in this patient. Single-cell RNA sequencing suggests that long-lived Trm may contribute to the persistence of immune surveillance through self-renewal and generation of cytotoxic TEMRA. This study offers insights into long-term anti-tumor immunity and may inform future optimization of cancer vaccine therapy.