Identification of Novel Breast Cancer Antigens Using Phage Antibody Libraries.

摘要

The purpose of this project is to use phage antibody libraries to identify novel breast tumor antigens. The antibodies could be used for breast cancer immunotherapy and the antigens could be used as cancer vaccines. In the first year, we used a model system to identify the factors allowing successful phage antibody library selection on tumor cell lines. Multivalent display of phage antibodies led to more efficient selection of cell binding antibodies, as did recovery of phage from within the cell after binding to an internalizing cell surface receptor. The methods were used to select a panel of phage antibodies which bound the breast tumor cell line SKBR3. Some of the antibodies bound ErbB2, some the transferring receptor, and one a novel antigen overexpressed on breast tumor cells. All were efficiently endocytosed as native antibody fragments and thus potentially useful for targeted cancer therapy. To widen the utility of this approach, a large human phage antibody library was constructed in a true phage vector in which multiple copies of antibody fragment are displayed on each phage. We have validated the utility of this library and are currently in the process of characterizing a large panel of breast tumor cell specific antibodies. We also developed a high throughput assay which allows rapid screening of unpurified antibody fragments for endocytosis into tumor cells.