DNA-mediated assembly of multi-specific antibodies for T cell engaging and tumor killing

Targeting T-cells against cancer cells is a direct means of treating cancer, and already showed great responses in clinical treatment of B-cell malignancies. A simple way to redirect T-cells to cancer cells is using multi-specific antibody (MsAb) that contains different arms for specifically “grabbing” the T-cells and cancer cells; as such, the T-cells are activated upon target engagement and the killing begins. Here, a Nucleic Acid mediated Protein-Protein Assembly (NAPPA) approach is implemented to construct a MsAb for T-cell engaging and tumor killing. Anti -CD19 and -CD3 single-chain variable fragments (scFvs) each are conjugated to different L-DNAs with sequences that form the Holliday junction, thus allowing spontaneous assembly of homogeneous protein-DNA oligomers containing two anti-CD19 and one anti-CD3 scFvs. The new MsAb shows strong efficacy in inducing Raji tumor cell cytotoxicity in the presence of T-cells with EC 50 ~ 0.2 nM; it also suppresses tumor growth in the Raji xenograft mouse model. The data indicate that MsAbs assembled from protein-DNA conjugates are effective macromolecules for directing T-cells for tumor killing. The modular nature of the NAPPA platform allows rapid generation of complex MsAbs from simple antibody fragments, while offering a general solution for preparing antibodies with high-order specificity.