Enhancing immune responses of ESC-based TAA cancer vaccines with a novel OMV delivery system

Area of Science:

• Immunology
• Biotechnology
• Oncology

Background:

• Embryonic stem cell (ESC)-derived epitopes show promise as cancer vaccines but suffer from poor immunogenicity and weak CD8+ T cell responses.
• Bacterial outer membrane vesicles (OMVs) are effective immunoadjuvants and delivery vectors for tumor antigens.

Purpose of the Study:

• To develop an engineered OMV platform for co-delivery of ESC-derived tumor antigens (TAAs) and PD-L1 antibodies to enhance anti-tumor immunity.
• To improve the efficacy of ESC-based cancer vaccines by enhancing T cell responses and increasing antigen residence time.

Main Methods:

• Engineered bacterial outer membrane vesicles (OMVs) by fusing SpyCatcher (SpC) and Staphylococcal Protein A (SpA) to OmpA.
• Developed a system for OMV conjugation with ESC-derived TAAs and anti-PD-L1 antibody using SpyTag-peptide and SpA-antibody interactions.
• Evaluated the therapeutic efficacy of the OMV-based combination therapy in a mouse tumor model.

Main Results:

• The engineered OMVs efficiently conjugated with TAAs and PD-L1 antibody, increasing TAA residence time.
• Combination therapy significantly inhibited tumor growth in mice.
• Treatment enhanced IFN-γ-producing CD8+ T cell responses, increased CD8+ memory cells, and boosted antigen-specific T cells.

Conclusions:

• The novel OMV platform enables effective co-delivery of ESC-derived TAAs and immune checkpoint inhibitors.
• This OMV-based delivery system enhances anti-tumor immune responses and holds potential for developing effective cancer vaccines.