Comprehensive Identification of Tumor-associated Antigens via Isolation of Human Monoclonal Antibodies that may be Therapeutic

Abstract

Although the success of trastuzumab and rituximab for treatment of breast cancer and non-Hodgkins lymphoma, respectively, suggests that monoclonal antibodies (mAbs) will become important therapeutic agents against a wider range of cancers, useful therapeutic Abs are not yet available for the majority of the human cancers because of our lack of knowledge of which antigens (Ags) are likely to become useful targets. We established a procedure for comprehensive identification of such Ags through the extensive isolation of human mAbs that may be therapeutic. Using the phage-display Ab library we isolated a large number of human mAbs that bind to the surface of tumor cells. They were individually screened by immunostaining, and clones that preferentially and strongly stained the malignant cells were chosen. The Ags recognized by those clones were isolated by immunoprecipitation and identified by mass spectrometry (MS). We isolated 2,114 mAbs with unique sequences and identified 25 distinct Ags highly expressed on several carcinomas. Of those 2,114 mAbs 434 bound to specifically to one of the 25 Ags. I am going to discuss how we could select proper target Ags for therapeutic Abs and candidate clones as therapeutic agents.

Antibody-dependent cell-mediated cytotoxicity is induced by a single-chain Fv-protein III fusion in the presence of a rabbit anti-protein III polyclonal antibody

“…Progress has been made in the development of phage-display antibody technology that has enabled the isolation of cancerspecific fully human monoclonal antibodies more readily [1]. Moreover, extensive screenings for mAbs that are specific for the cell-surface antigens of various types of cancer-derived cell lines have increased the number of candidate clones that may have therapeutic value.…”

“…In a number of attempts to isolate antibodies from phage libraries, many groups have focused on a single or a small number of well-known cancerspecific antigens. Other laboratories have succeeded in isolating a large number of mAb clones against all possible target antigens on the surfaces of cancer cells [1]. However, a comprehensive isolation of candidate mAbs such as this necessitates a high-throughput method for the evaluation of their therapeutic potential.…”