PROTAC‐Engineered Protein/DNA Nanoantigen is a Potent Booster for Dendritic Cell Vaccines in Cancer Immunotherapy

ABSTRACT

The efficacy of dendritic cell (DC) vaccines in cancer immunotherapy is often limited by weak immunogenicity due to inefficient antigen cross‐presentation (XPT). We previously combined a calcium carbonate (CaCO ₃ ) delivery system with a proteolysis‐targeting chimera (PROTAC) to enhance antigen degradation. Along this line, we developed a protein/DNA‐integrated nanoantigen platform (HpOAC) co‐loading CaCO ₃ with a His‐tagged ovalbumin (O) modified with the von Hippel‐Lindau (VHL) E3 ligase‐recruiting peptide ALAPYIP (HOA) and a eukaryotic plasmid encoding O‐ALAPYIP (pOA). HpOAC promoted DC maturation and migration via Ca ²⁺ release. Mechanistically, HOA provided an immediate antigen source, while pOA enabled sustained expression; both underwent ALAPYIP‐mediated VHL recruitment, enhancing O ubiquitination and proteasomal degradation, thereby amplifying XPT. Consequently, HpOAC‐DCs induced strong OT‐I/OT‐II T cell proliferation in vitro. In vivo, a single immunization with HpOAC‐DCs significantly suppressed tumor growth and elicited durable antigen‐specific T helper type 1 and cytotoxic T lymphocyte responses, outperforming single‐antigen vaccines. Under a two‐dose regimen, its anti‐tumor efficacy was improved compared to non‐PROTAC and in situ antigen vaccines. Thus, we constructed a PROTAC‐enhanced, protein/DNA‐integrated DC vaccine platform that synergizes immediate and sustained antigen supply with Ca ²⁺ ‐mediated adjuvanticity, offering a highly promising strategy for novel DC vaccine design.