The Need

Liposome drug delivery systems play a significant role in the formulation of new therapies. These liposome-encapsulated drugs are used to treat a wide range of diseases such as cancer, influenza, and hepatitis. While endogenous liposomes are recognized by the mononuclear phagocyte system and cleared from the blood stream, the development of high-stability, long-circulating liposomes (i.e. ‘stealth liposomes’) was a substantial improvement in lipid-based drug delivery technology. This improvement emerged from using lipids of the liposome membrane to anchor polyethylene glycol (PEG) compounds by a single covalent bond to the liposome surface. Used in this way, the presence of PEG prevents serum protein from binding to the liposome and precipitating immunoclearance. However, all PEG-incorporated stealth liposome technologies have a practical weakness: they cannot tolerate dehydration and therefore cannot tolerate anhydrous storage. Therefore, the state of liposome drug delivery technology would be improved by a technology that performs at least as well as PEG-dependent technology and also addresses this fundamental flaw.

The Technology

Researchers at The Ohio State University, led by Dr. Dennis Bong, have developed a new variety of stealth liposome technology that uses sugar-based polymers rather than PEG. These sugar-based polymers provide stability to liposomes during anhydrous storage, therefore addressing the flaw of PEG-dependent stealth liposomes. This increased stability occurs because each sugar-based polymer binds numerous lipid anchors of the liposome membrane, as opposed to PEG’s single bond. This cross-linking results in a highly-branched structure that is substantially more-stable than is possible using PEG-dependent technology. Additionally, relative to currently-used, PEG-dependent stealth liposomes, this new sugar-based polymer technology both elicits less immunoactivity from the mononuclear phagocyte system and also has an increased period of circulation.

Commercial Applications

• Improvement to liposome-based drug delivery systems

• Minimizing the immune-footprint of stealth liposome technology

Benefits/Advantages

• While currently-used PEG-dependent stealth liposomes are unstable in dry storage, this new stealth liposome technology uses sugar-based polymers to provide stability during dry storage

• New stealth liposomes that incorporate sugar-based polymers have a longer period of circulation for effective drug delivery versus PEG technology.