(623e) Engineering of Virus-like Particles Functionalized with CD47 Extracellular Domain to Improve Targeted Delivery By Avoiding Macrophages

Targeted drug delivery is important to both improve the drug efficacy and reduce side effects. Virus-like particles (VLPs) have been engineered to be used as targeted drug delivery vehicles. VLPs are self-assembled, homogeneous nanoparticles derived from the viral capsid and contain no genetic material. The Swartz Lab has engineered Hepatitis B core VLPs to be stable during manufacture and storage, but to lose stability under cytoplasmic conditions, allowing us to release the drug cargo once the VLP is inside the cells. Additionally, the Swartz Lab has developed a process to functionalize the VLP surface by incorporating non-natural amino acids (nnAAs) using cell-free protein synthesis technology. By incorporating a nnAA with an azide group on the VLP and a nnAA with an alkyne group on the ligands, we can decorate the VLP surface with multiple ligands using the copper(I)-catalyzed azide-alkyne cycloaddition (â??clickâ?) reaction. With this approach, each VLP can accommodate up to 120 ligands including targeting molecules such as antibody fragments on the surface.

One major challenge in using VLPs as a drug delivery vehicle is avoiding phagocytic clearance before reaching the targeted cells. For this purpose, the CD47 extracellular domain will be displayed on the VLP surface. CD47 is known as the â??marker of selfâ?, because its extracellular domain interacts with SIRPα on phagocytes to inhibit phagocytosis. Several CD47 extracellular domain variants have been produced using cell-free protein synthesis and displayed on the VLP surface using the â??clickâ? reaction. These VLPs will be further functionalized with targeting molecules for specific delivery to prostate cancer cells. The CD47-functionalization will enhance the delivery efficiency of the VLPs by avoiding macrophage engulfment.