Potentiating cancer immunotherapy using an oncolytic virus

Area of Science:

• Immunology
• Virology
• Oncology

Background:

• Oncolytic viruses (OVs) are potent anti-cancer agents but their immunogenicity limits efficacy in immune-competent hosts.
• Strategies to overcome OV immunogenicity, such as immunosuppression, may compromise anti-tumor immunity.
• A novel approach is needed to harness the immune response against OVs for enhanced therapeutic outcomes.

Purpose of the Study:

• To develop and evaluate a strategy where the immune response against an oncolytic virus leads to improved therapeutic results.
• To investigate the combined effect of adenoviral (Ad) immunization and oncolytic vesicular stomatitis virus (VSV) treatment expressing a shared tumor antigen.
• To assess the impact of treatment intervals on viral replication, anti-tumor immunity, and safety.

Main Methods:

• Immunization of hosts with an Ad vaccine expressing a tumor antigen.
• Subsequent treatment with an oncolytic VSV expressing the same tumor antigen.
• Evaluation of viral replication, anti-tumoral immune responses, and therapeutic efficacy in tumor-bearing models.

Main Results:

• Ad immunization followed by VSV treatment significantly enhanced anti-tumoral immunity.
• Intratumoral VSV replication was minimally affected by Ad immunization, and longer intervals increased efficacy.
• The combination therapy shifted immune responses from viral to tumor antigens, improving safety and efficacy.

Conclusions:

• Pre-existing anti-viral immunity can be leveraged to boost anti-tumor responses using oncolytic viruses.
• This strategy enhances both the efficacy and safety of oncolytic virus therapy.
• The approach shows promise for various vector combinations, tumor antigens, and cancer types.