A nanoparticle vaccine that targets neoantigen peptides to lymphoid tissues elicits robust antitumor T cell responses

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Clinical trials with synthetic long peptides (SLP) for cancer vaccines have yielded limited success, potentially due to a predominant CD4+ T cell response.
• Effective cancer vaccines require robust CD8+ and CD4+ T cell activation for improved anti-tumor efficacy.

Purpose of the Study:

• To investigate if enhanced delivery of peptide antigens to secondary lymphoid tissues can elicit stronger T cell responses and better anti-tumor effects.
• To design and evaluate SLP-containing cationic lipoplexes (SLP-Lpx) for improved antigen presentation and immune stimulation.

Main Methods:

• Development of SLP-containing lipoplexes (SLP-Lpx) for targeted delivery of neoantigens to myeloid cells in lymphoid tissues.
• Immunization of mice with naked synthetic peptides versus SLP-Lpx using G12D KRAS mutations as neoantigens.
• Assessment of CD4+ and CD8+ T cell responses and tumor growth inhibition.
• Evaluation of combination therapy with SLP-Lpx vaccines and checkpoint inhibitors.

Main Results:

• Naked synthetic peptides with CpG adjuvant primarily induced CD4+ T cell responses and showed limited tumor growth inhibition.
• SLP-Lpx vaccination stimulated both CD4+ and CD8+ T cells, leading to CD8+ T cell-dependent tumor growth suppression.
• Combining SLP-Lpx vaccines with checkpoint inhibitors resulted in significant suppression of established tumors.

Conclusions:

• Targeting neoantigen-derived peptides to the spleen using lipoplexes elicits potent CD4+ and CD8+ T cell responses.
• SLP-Lpx vaccines represent a promising strategy for enhancing anti-tumor immunity, particularly when combined with immune checkpoint inhibitors.