ENABLING ENCAPSULATION OF BIOLOGICS IN POLYMERIC NANOCARRIERS: TECHNOLOGY DESIGN FROM PROCESS TO APPLICATION

Abstract

Proteins and peptides are therapeutic modalities employed with increasing frequency in the clinic because of their excellent specificity and potency. Microparticle depots and nanocarrier formulations, such as liposomes, are the two formulation technologies that have received the greatest attention for their potential to address challenges with rapid blood clearance and membrane permeability. Despite extensive work, no nanocarrier formulations for peptides or proteins have been marketed. A universal challenge with these technologies is that the fabrication processes are not scalable and are not economical. Inverse Flash NanoPrecipitation (iFNP) has been demonstrated to overcome these barriers for microparticle depots. The iFNP process uses rapid micromixing in specific mixing geometries to assemble “inverse nanocarriers” containing a water-soluble therapeutic within a core that is stabilized by an amphiphilic block copolymer in a hydrophobic solvent phase. These inverse nanocarriers can then be emulsified to form microparticles at 10-fold higher loadings than possible with existing techniques.

Herein, we describe the use of iFNP to form polymeric nanocarriers as a replacement for liposome formulations. We detail scalable processing methods to create water-dispersible nanocarriers and demonstrate that these methods achieve 5-15x higher loadings than alternative methods. We then develop design rules for key platform metrics: in vivo functionality, controlled release, and biologic stability during processing. We identify formulation properties that impart stability of nanocarrier surface charge and size in physiological buffers, which is crucial for in vivo efficacy. We establish the impact of polymer properties on release control, demonstrating a range of release rates, from minutes to days, as a function of formulation design. Finally, we assess chemical and physical stability of several model proteins. We first apply a combined experimental/simulations approach to understand folding behavior for a miniprotein. Based on suspected unfolding mechanisms, we also implement iFNP process modifications that result in complete activity retention for a 460 kDa protein initially denatured in the standard process. These advances demonstrate the economic viability and superiority of iFNP as a nanocarrier formulation and expand the classes of therapeutics that can be encapsulated using the technique.