Intravenous Nanoparticle Vaccination Generates Stem-Like TCF1(+) Neoantigen-Specific CD8(+) T Cells

Personalized cancer vaccines are a promising approach for inducing T cell immunity to tumor neoantigens. Using a self-assembling nanoparticle vaccine that links neoantigen peptides to a TLR7/8 agonist (SNP-7/8a), we show how the route and dose alter the magnitude and quality of neoantigen-specific CD8(+) T cells. Intravenous vaccination (SNP-IV) induced a higher proportion of TCF1(+)PD-1(+) CD8(+) T cells compared to subcutaneous immunization (SNP-SC). Single cell RNA-seq showed that SNP-IV induced stem-like genes (Tcf7, Slamf6, Xcl1) whereas SNP-SC enriched for effector genes (Gzmb, Klrg1, Cx3cr1). Stem-like cells generated by SNP-IV proliferated and differentiated into effector cells upon checkpoint blockade leading to superior antitumor response compared to SNP-SC in a therapeutic model. The duration of antigen presentation by dendritic cells controlled the magnitude and quality of CD8(+) T cells. These data demonstrate how to optimize antitumor immunity by modulating vaccine parameters for specific generation of effector or stem-like CD8(+) T cells.