<i>In Situ</i> Tumor Surface Modification with Antibody Fragments for Antigen-Independent Versatile Cancer Immunotherapy

Natural killer (NK) cells exert potent cytotoxic effects by releasing perforin, granzyme B, and immune-boosting cytokines upon recognition of antibody-coated targets. However, the heterogeneous expression of tumor antigens poses a major limitation to NK-mediated antibody-dependent cell-mediated cytotoxicity (ADCC). To overcome this challenge, we developed a Universal Antibody (Univody), a recombinant fusion protein that enables an antigen-independent presentation of Fc fragments on the surface of cancer cells. Specifically, the Fc region of human IgG1 was fused with a transmembrane domain and delivered in the form of plasmid DNA, ensuring stable membrane localization and interaction with NK cell receptors. For efficient and selective delivery, we employed a phenylboronic acid (PBA)-modified lipopolyplex (LPP-PBA), which significantly enhanced cellular uptake and transfection efficiency while reducing cytotoxicity. The plasmid DNA encoding Univody (pUnivody) effectively decorated a variety of heterogeneous tumor types with Fc fragments, leading to NK cell activation and enhanced immune responses in the tumor microenvironment. <i>In vivo</i>, pUnivody@LPP-PBA treatment resulted in marked tumor inhibition in both triple-negative breast cancer and melanoma models. This antigen-independent platform broadens the scope of antibody therapy and immunotherapy, offering a versatile approach to treating multiple types of cancers.