Abstract 2511: Tumor cell-specific full-length human antibodies from Epstein-Barr virus-immortalized sentinel node B lymphocytes from breast cancer patients

Abstract

Abstract It has been demonstrated that patients do develop autoantibodies to a solid tumor, but the level of the antibody response is too low to have significant antitumor effect. This means that there are B cell clones producing antitumor antibodies, but they are suppressed (or not activated sufficiently) by the complex immunoregulatory systems in cancer patients. When the B cell repertoire is transferred out of the human cancer patient, in vitro methods allow the selection of anti-tumor antibodies and can then allow unrestricted production of sufficient quantities for clinical use. There are a variety of options available for the in vitro generation of antibodies from human B cells that are basically based on the recombinant production following gene cloning, and on B cell immortalization, their propagation and antibody secretion in cell culture. Most popular forms of recombinant expression of antibodies are phage displayed scFv and Fab antibody libraries, which have disadvantage of loss of original heavy and light chain pairings, inability to display full antibody, and production in bacterial host cells. The antibodies produced by B cell immortalization do not suffer from these drawbacks and retain their original heavy and light chain pairings. We collected fresh sentinel nodes and breast tumor specimens from cancer patients and following B lymphocyte separation from sentinel nodes they were immortalized using Epstein-Barr virus (EBV). The antibodies secreted from the immortalized B cells were studied for binding to the tumor cells of established cell lines and to the tumor cell surface protein preparations from the same patient that the B cells were derived. Using cell-ELISA and dot blot techniques, we identified several antibodies that were found to bind intact tumor cells and to the cell surface protein preparations derived from patient's tumors. It is expected that cancer-specific antibodies identified by B cell immortalization method will be candidates for therapeutic and diagnostic applications and further studies to identify their target antigens and bioactivity will help in understanding the humoral immune response to these breast cancer antigens and their role in the cell proliferation and tumor growth. An innovative aspect of this study is the exploitation of the cancer patients’ own immune repertoire for generating therapeutic antibodies. This is in contrast to most of the currently available therapeutic antibodies for clinical use, which are derived from chimerization or humanization of rodent antibodies. Currently no commercially available mAb has been developed through the selective and regulatory processes of the human immune system. The ability to reliably and rapidly generate tumor-binding antibodies from patients’ own B cells will have broad applicability and provide a platform for developing innovative therapeutic and diagnostic reagents. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2511. doi:1538-7445.AM2012-2511