Decade-long WT1-specific CTLs induced by WT1 peptide vaccination

Area of Science:

• Immunology
• Oncology
• Vaccinology

Background:

• Peptide-based cancer vaccines targeting Wilms' tumor 1 (WT1) show promise for hematological malignancies.
• The long-term persistence and extent of WT1-specific CD8+ cytotoxic T lymphocytes (CTLs) after vaccination remain unclear.

Purpose of the Study:

• To investigate the long-term persistence of WT1-specific CTLs after peptide vaccination in a patient with chronic myeloid leukemia (CML).
• To analyze the T-cell receptor (TCR) repertoire and functional cytotoxicity of these persistent CTLs.

Main Methods:

• Administration of a WT1 peptide vaccine to a CML patient.
• Longitudinal immune monitoring for over 12 years post-vaccination.
• Specific amplification of WT1-specific CTLs and TCR repertoire analysis using next-generation sequencing.

Main Results:

• WT1-specific CTLs persisted at low frequencies (less than 5 cells/1,000,000 CD8+ T cells) for over 10 years.
• TCR repertoire analysis confirmed the diversity of WT1-specific CTLs 11 years post-vaccination.
• In vitro assays demonstrated WT1 peptide-specific cytotoxicity of the CTLs.

Conclusions:

• The WT1 peptide vaccine induces a durable immune response in CML patients.
• WT1-specific CD8+ CTLs can persist for more than a decade after vaccination cessation.
• This study highlights the potential for long-term immunotherapeutic efficacy of WT1 peptide vaccines.