Millions of people in the United States suffer from neurological diseases such as Alzheimer's disease, stroke, and brain cancer. Advances in protein/gene profiling techniques and high throughput drug screening technologies have spawned many new drug candidates. However, the blood-brain barrier (BBB) will hamper the development and clinical realization of this new generation of neurotherapeutics. This is because unless a drug is small (<500 Da) and lipophilic, it does not effectively transport from the bloodstream, across the BBB, and into the brain. As a consequence of these restrictions on brain drug attributes, the uptake of most small molecule therapeutics is extremely limited, while protein and gene medicines are not BBB permeable. A noninvasive delivery method with considerable promise involves the employ of endogenous BBB transport mechanisms as a means to shuttle drug cargo from the blood to the brain. Such receptor-mediated transport systems can be targeted using the exquisite specificity of antibodies that are in turn linked to a drug payload that can include small molecules, proteins, or DNA therapeutics. After binding to the receptor on the blood side, the antibody-drug conjugate acts as an artificial substrate for the transporter and will transcytose across the BBB into the brain. Current approaches have yielded limited brain uptake because the targeted transporters are ubiquitously expressed, and the antibody targeting reagents have a lower than expected BBB permeability. Therefore, this proposal is focused on the discovery and characterization of novel antibody delivery vectors having improved brain specificity and transport efficiency. Large human single- chain antibody (scFv) libraries will be searched for novel antibodies that bind to and endocytose into brain endothelial cells via cognate cell surface transport systems. These antibodies will be tested for their ability to transcytose across an in vitro BBB model, and will be quantitatively ranked for transport efficiency based their BBB permeability. Finally, the brain targeting and transcytosing scFv will be grafted onto a human IgG scaffold for in vivo testing. Pharmacokinetic profiling will be performed to determine organ uptake of brain targeting IgG in the rat. Those antibodies exhibiting significant and specific brain uptake will have excellent potential as noninvasive brain drug delivery vectors.

Public Health Relevance

Identification of novel noninvasive routes for drug delivery to the brain would have a significant impact on our ability to translate new therapeutics into clinically viable drugs for the treatment of millions of patients who suffer from debilitating neurological diseases. In particular, delivery approaches coupling antibodies with BBB-specific transport systems would be no more invasive than an intravenous injection and allow delivery of a variety of drug cargoes including small molecules, genes, and proteins. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21EY018506-02
Application #
7477497
Study Section
Special Emphasis Panel (ZRG1-GGG-S (52))
Program Officer
Oberdorfer, Michael
Project Start
2007-08-01
Project End
2010-07-31
Budget Start
2008-08-01
Budget End
2010-07-31
Support Year
2
Fiscal Year
2008
Total Cost
$179,990
Indirect Cost
Name
University of Wisconsin Madison
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Tillotson, Benjamin J; Cho, Yong Ku; Shusta, Eric V (2013) Cells and cell lysates: a direct approach for engineering antibodies against membrane proteins using yeast surface display. Methods 60:27-37
Cho, Yong Ku; Shusta, Eric V (2010) Antibody library screens using detergent-solubilized mammalian cell lysates as antigen sources. Protein Eng Des Sel 23:567-77
Cho, Yong Ku; Chen, Irene; Wei, Xin et al. (2009) A yeast display immunoprecipitation method for efficient isolation and characterization of antigens. J Immunol Methods 341:117-26