BACKGROUND With the rapid development of immune checkpoint inhibitors and neoantigen (NeoV)-based personalized tumor vaccines,tumor immunotherapy has shown promising therapeutic results. However,the limited efficacy of available tumor vaccines impedes the development of personalized tumor immunotherapy. In this study,we developed a novel tumor vaccine system and proposed combined therapeutic strategies for improving treatment effects. METHODS We developed a novel tumor vaccine system comprising a newly synthesized peptidic microarchitecture (PMA) with high assembly efficacy. The PMA-trapped neoantigen vaccine was developed to codeliver tumor neoantigen and the Toll-like receptor 9 agonist CpG (NeoV),abbreviated as PMA-NeoV. A microfluidic chip was used to produce PMA particles in a uniform and precise manner. Vaccine effectiveness was investigated both in vitro and in vivo. The combined immunotherapeutic effect of PMA-NeoV with anti-programmed cell death ligand 1 antibody (aPD-L1) or with the phosphatidylinositol 3?‘kinase $\gamma$ (PI3K$\gamma$) inhibitor IPI-549 was further tested in MC38 mouse tumor model. RESULTS PMA-NeoV not only promoted codelivery of the tumor vaccine but also potentiated vaccine immunogenicity. Moreover,compared with free NeoV,PMA-NeoV significantly increased the number of tumor-infiltrating lymphocytes,promoted the neoantigen-specific systemic immune response,and suppressed murine colon MC38 tumor growth. Furthermore,PMA-NeoV increased the expression of programmed cell death receptor-1 on T lymphocytes,and in combination with aPD-L1 eradicated seven of eight MC38 tumors by rescuing exhausted T lymphocytes. Moreover,we combined the PMA-NeoV with the IPI-549,a molecular switch that controls immune suppression,and found that this combination significantly suppressed tumor growth and eradicated five of eight inoculated tumors,by switching suppressive macrophages to their active state and activating T cells to prime a robust tumor immune microenvironment. CONCLUSIONS We developed a tumor vaccine delivery system and presented a promising personalized tumor vaccine-based therapeutic regimen in which a tumor vaccine delivery system is combined with an aPD-L1 or PI3K$\gamma$ inhibitor to improve tumor immunotherapy outcomes.
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