Designing Programmable Peptide Nucleic Acid-based Nanovaccines for Anticancer Immune Activation

Targeted delivery of antigens and adjuvants to the immune cells without eliciting uncontrolled inflammation is a major challenge in cancer vaccine development. Here, a highly versatile and programmable peptide nucleic acid (PNA)-based vaccine nanoplatform (PVN) is reported to elicit a robust anti-tumor immune response against B16-OVA syngeneic melanoma model. The PVN is built on an 11-mer PNA scaffold, enabling efficient "one-pot" loading of a PNA-modified ovalbumin antigenic peptide (SIINFEKL), CpG adjuvant, and a PNA-derivatized LLP2A ligand (an immune cell and melanoma cell targeting ligand). Super-resolution fluorescence imaging reveals the spatial arrangement of OVA₈ within LP_10-12[OVA₈/CpG/LLP2A], while circular dichroism spectroscopy confirmsparalleled binding of complementary PNA strands in LP₁₁[OVA₈/CpG/LLP2A]. LLP2A displayed on PVNs target activated α4β1 integrin expressed by immune and melanoma cells, boosting antigen presentation by dendritic cells and eliciting strong CD8+T cell   and natural killer cell responses. This amplified antitumor immune response leads to significant tumor regression and prolonged survival of mice bearing syngeneic B16-OVA melanoma. The modular nature and versatility of PVN allow convenient one-pot assembling of peptide antigens, immunomodulators, immune cell and tumor cell targeting ligands, making it practical for the custom design and preparation of personalized cancer vaccines.