Heterologous arenavirus vector prime-boost overrules self-tolerance for efficient tumor-specific CD8 T cell attack

Area of Science:

• Immunology
• Virology
• Oncology

Background:

• Inducing effective tumor-specific CD8+ T lymphocyte (CTL) responses for cancer therapy remains a significant challenge.
• Current therapeutic vaccination strategies often struggle to overcome self-tolerance and achieve robust anti-tumor immunity.

Purpose of the Study:

• To engineer arenavirus vectors for therapeutic cancer vaccination.
• To evaluate the efficacy of a heterologous prime-boost regimen using engineered arenaviruses in controlling established solid tumors.

Main Methods:

• Two distantly related arenaviruses (Pichinde virus and lymphocytic choriomeningitis virus) were engineered as life-replicating vectors.
• A heterologous prime-boost vaccination strategy was employed in mice, delivering a self-antigen.
• Tumor-specific CTL responses, tumor elimination, and protection against rechallenge were assessed.

Main Results:

• The engineered arenavirus vectors induced potent tumor-specific CTL responses, reaching up to 50% of the circulating CD8 T cell pool.
• This immunotherapy regimen led to the elimination of established solid tumors in a significant proportion of treated mice.
• Animals receiving the therapy were protected against subsequent tumor rechallenge.

Conclusions:

• Arenavirus-based immunotherapy, utilizing distantly related viral vectors in a heterologous prime-boost regimen, can effectively break self-tolerance and induce potent anti-tumor CTL responses.
• This approach demonstrates significant potential for controlling established tumors and warrants further investigation as a novel cancer immunotherapy strategy.