(789h) Engineering Functionalized Virus-like-Particles with Antibody Fragments to Target Cancer Biomarkers

Swartz, J. R., Stanford University
Functionalized Virus-Like particles (VLPs) are promising nano-particle vehicles for drug delivery or diagnostic applications. Our lab has done extensive work in developing a Hepatitis B core protein based VLP, with an artificially introduced disulfide bond network for added stability. These particles can target cancer cells by functionalizing their surface with antibody fragments, DNA or RNA aptamers using Cu(II) catalyzed click chemistry. The presence of multiple targeting agents on each VLP enhances targeting specificity due to avidity effects. In this paper, we present work on developing antibody fragments with non-natural amino acids (nnAAs), based on the J591 antibody, to target Prostate Specific Membrane Antigen (PSMA), a protein over-expressed on prostate cancer cell-lines. Using our E. coli based Cell Free Protein Synthesis (CFPS) platform, we incorporate nnAAs on both the spikes of the VLP (azide side chain) and the antibody fragments (alkyne side chain). Using metabolically engineering cell lines, we are able to express full-length single chain variable fragments (scFvs) and Fragment Antigen-binging (Fab) proteins containing nnAAs. These antibody fragments have been used in developing luminescent nanoparticles to detect and enumerate Circulating Tumor Cells. This work can be extended to target other cancer biomarkers for drug delivery.