Utilizing VEGF165b mutant as an effective immunization adjunct to augment antitumor immune response

Area of Science:

• Immunology
• Oncology
• Vaccinology

Background:

• Vascular Endothelial Growth Factor (VEGF) blockade shows promise in cancer therapy by inhibiting angiogenesis and reducing immune suppression.
• VEGF antibodies can promote T cell infiltration into tumors, suggesting a role in enhancing anti-tumor immunity.
• Developing adjuncts to peptide cancer vaccines is crucial for augmenting immune responses and overcoming tumor-induced tolerance.

Purpose of the Study:

• To evaluate the potential of a novel mutant VEGF165b as a co-immunization adjunct for a peptide-based cancer vaccine.
• To determine if co-immunization with mVEGF165b enhances the immune response against a MUC1 peptide vaccine in a mouse model of breast cancer.
• To investigate the impact of mVEGF165b on regulatory T cells (Tregs) and effector T cell responses.

Main Methods:

• Mice with breast cancer were co-immunized with mVEGF165b and a MUC1 peptide vaccine.
• VEGF antibody titers were measured to assess the immune response to mVEGF165b.
• The frequency of regulatory T cells (Tregs) and MUC1-specific CD8+ T cell responses (IFN-γ production) were analyzed.
• Antitumor efficacy and survival rates were evaluated in tumor-bearing mice.

Main Results:

• Co-immunization with mVEGF165b resulted in a dramatic increase (approx. 600,000-fold) in VEGF antibody titers.
• The anti-VEGF antibody treatment significantly reduced the frequency of Tregs in both preventive and therapeutic settings.
• A notable increase in MUC1-specific IFN-γ-producing CD8+ T cells and anti-MUC1 humoral response was observed.
• Combination therapy led to superior antitumor responses and significantly prolonged survival in tumor-bearing mice.

Conclusions:

• The mutant mVEGF165b serves as an effective immunization adjunct to enhance peptide cancer vaccine immunogenicity.
• mVEGF165b overcomes immune tolerance, likely by reducing Tregs and promoting effector T cell responses.
• This combination strategy holds promise for improving the efficacy of peptide-based tumor vaccines in cancer immunotherapy.