A Designer Nanoparticle Platform for Controlled Intracellular Delivery of Bioactive Macromolecules: Inhibition of Ubiquitin-Specific Protease 7 in Breast Cancer Cells

Biological therapeutics represent an increasing and critical component of newly approved drugs; however, the inability to deliver biologics intracellularly in a controlled manner remains a major limitation. We have developed a semi-synthetic, tunable phage-like particle (PLP) platform derived from bacteriophage λ. The shell surface can be decorated with small-molecule, biological and synthetic moieties, alone or in combination and in defined ratios. Here, we demonstrate that the platform can be used to deliver biological macromolecules intracellularly and in a controlled manner. Ubiquitin-specific protease 7 (USP7) is a deubiquitinating enzyme that has been widely recognized as an ideal target for the treatment of a variety of cancers. Recently, UbV.7.2, a novel biologic derived from the ubiquitin scaffold, was developed for inhibition of USP7, but issues remain in achieving efficient and controlled intracellular delivery of the biologic. We have shown that decoration of PLPs with trastuzumab (Trz), a HER2-targeted therapeutic used in the treatment of various cancers, results in specific targeting and uptake of Trz-PLPs into HER2-overexpressing breast cancer cells. By simultaneously decorating PLPs with Trz and UbV.7.2, we now show that these particles are also internalized by HER2-positive cells, thus providing a means for intracellular delivery of the biologic in a controlled fashion. Internalized particles retain USP7 inhibition activity of UbV.7.2 and alter the metabolic and proteomic landscapes of these cells. This study demonstrates that the λ "designer nanoparticles" represent a powerful system for the intracellular delivery of biologics in a defined dose.