Tunable antigen density improves a cancer vaccine in mice

An MIT team repurposed the harmless-to-humans M13 bacteriophage as a personalized cancer-vaccine carrier. The phage forms a long nanofiber; by changing charge and expression speed in its pVIII coat protein, researchers tuned tumor-antigen density from 6% to 70%. Its single-stranded DNA also activates TLR9, putting antigen display and adjuvant activity in one particle. In mice, a 35% density vaccine was taken up more readily by dendritic cells than a 6% version, generated more targeted T cells, and reduced formation of melanoma expressing a model antigen. Swapping in the colon-cancer neoantigen ADPGK also reduced colon-tumor formation. The platform could exchange antigens for an individual tumor, but the evidence is still a preventive mouse model, not a human treatment result. Efficacy against established tumors, loading of diverse antigens, manufacturing consistency, toxicity, immune escape and clinical trials remain unproven.