Selection and analysis of anti‐cancer antibodies for cancer therapy obtained from antibody phage library

Abstract

The search for effective antibodies (Ab) for curable cancer immunotherapy has been a quest of many research groups in order to find an effective target that exists on the cancer cell surface. So far there have been no conclusive answers to shed light on the search. This study therefore aimed to bridge the gap of cancer therapy. Screening against 49 kinds of cell lines belonging to 11 kinds of solids cancers was performed. Isolation and characterization for approximately 4200 monoclonal antibodies (mAb) was also performed thereafter. Of those mAb 488 clones that turned out to bind to 29 tumor-associated antigens (TAA) were subjected to immunohistochemical (IHC) analyses. Selection of target antigens (Ag) and a potential antibody for cancer therapy was conducted prior to clinical examinations. In order to find predictably effective targets for therapeutic Ab against solid cancers, expression of the Ag on the surface of cancer and normal cells was extensively examined by IHC analyses using fresh cancer specimens resected from patients. In this study, the tendencies of all staining patterns and distribution of the Ab are reported. While all of the TAA appeared to be involved in tumorigenesis, their expression was not restricted to some specific tumor types but rather randomly distributed among various cancers. Some kinds of Ab including anti-epidermal growth factor receptor (EGFR) and anti-human epidermal growth factor receptor 2 (HER2) indicated the frequency of expression in normal cells was generally low. We concluded that identification of 488 mAb and the accumulated results of IHC analyses in this study could be the key for further therapeutic Ab against cancers. The targets that showed cancer-specific expression are expected to be better for therapeutic Ab than the other Ab. Moreover, further investigation into the growth of cancer cell lines using full human IgG form of Ab shows available efficacy in specific cases. (Cancer Sci 2011; 102: 175-181)

A 3D matrix platform for the rapid generation of therapeutic anti-human carcinoma monoclonal antibodies

“…Recent interest has focused on designing unbiased phenotypic screens wherein the identification of function-blocking effects precede efforts to dissect the underlying molecular mechanisms that give rise to the desired outcomes (13,15,31,32). With increasing evidence that cell behavior in 3D culture systems more faithfully recapitulates in vivo function, greater emphasis has been placed on developing improved in vitro models for screening purposes, including the use of basement membranelike gels, pepsin extracts of dermal collagen, and synthetic hydrogels (1, 2, 6, 33-35).…”

Screening for antibodies against intact cancer cells with a na�ve large phage antibody library

“…However, the composition of the cell surface is very complex, with many types of proteins, carbohydrates and lipids, but with a low number of tumor-specific antigens. Non-specific adhesion and loss of specific ligand are among the problems often faced when intact cancer cells are used as the target to screen an antibody library (15). Under these conditions, an antibody library of high diversity and library size is particularly important.…”

Phenotypic screening: the future of antibody discovery

“…To date, most antibodies identified by phenotypic screens have been found using a two-step process. First, antibody populations have been enriched against a target cell or tissue type before being screened for function [11][12][13][14][15][16][17][18]. A two-step process is dependent on the efficiency of both steps; however, the functional screen poses the greatest challenge and is often the bottleneck in the process.…”

“…There have been several successful phenotypic screens, performed on these enriched populations, which have generated antibodies against cancer cells and infectious agents. As early as 1995, de Kruif et al [11] screened for target cell specificity and more recent examples have followed [12][13][14]. Functional screens have also been performed that have identified antibodies that induce apoptosis [15], inhibit cell proliferation [16], or internalise [17,18].…”