Antibody engineering for tumor immunotherapy

Antibodies have been used as cancer therapeutics for several decades. One area in which this therapy may be improved is the retention time of antibody in the tumor relative to normal tissue. In this Thesis, we have attempted to elucidate the mechanisms that are most influential to improving antibodies as cancer therapeutics. Carcinoembryonic antigen (CEA) has long been identified as a tumor-associated antigen. CEA is also quite stable, with a cell-surface shedding half-life of approximately 7 days. Directed evolution methodology has been utilized to design an antibody fragment with properties that would improve tumor retention. Specifically, antibody engineering methods were used to produce a humanized, extremely high affinity and stable single chain antibody fragment (scFv) against CEA. Several mutant scFv libraries were constructed and screened against soluble CEA with yeast surface display and fluorescent activated cell sorting (FACS). A series of antibodies were engineered that span three orders of magnitude in off-rate improvement. These antibody fragments show excellent stability at physiologically relevant temperatures. In addition, soluble protein expression levels were greatly improved. The final product has a dissociation half-life of approximately 7 days, currently the longest engineered half-life of an scFv against a tumor-associated antigen. Binding and diffusion in micrometastases was also modeled to gain an improved understanding of the quantitative interplay among the rate processes of diffusion, binding, degradation, and plasma clearance in tumor microspheroids.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Graff, Christilyn Paula

Advisor dc:contributor.advisor

• K. Dane Wittrup.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29279

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29279