Differential responses of human tumor cell lines to anti-p185HER2 monoclonal antibodies

Abstract

The HER2 protooncogene encodes a receptor tyrosine kinase, p185HER2. The overexpression of p185HER2 has been associated with a worsened prognosis in certain human cancers. In the present work we have screened a variety of different tumor cell lines for p185HER2 expression using both enzyme-linked immunosorbent and fluorescence-activated cell sorting assays employing murine monoclonal antibodies directed against the extracellular domain of the receptor. Increased levels of p185HER2 were found in breast (5/9), ovarian (1/6), stomach (2/3) and colorectal (5/16) carcinomas, whereas all kidney and submaxillary adenocarcinoma cell lines tested were negative. Some monoclonal antibodies directed against the extracellular domain of p185HER2 inhibited growth in monolayer culture of breast and ovarian tumor cell lines overexpressing p185HER2, but had no effect on the growth of colon or gastric adenocarcinomas expressing increased levels of this receptor. The most potent growth-inhibitory anti-p185HER2 monoclonal antibody in monolayer culture, designated mumAb 4D5 (a murine IgG1 kappa antibody), was also tested in soft-agar growth assays for activity against p185HER2-overexpressing tumor cell lines of each type, with similar results. In order to increase the spectrum of tumor types potentially susceptible to monoclonal antibody-mediated anti-p185HER2 therapies, to decrease potential immunogenicity issues with the use of murine monoclonal antibodies for human therapy, and to provide the potential for antibody-mediated cytotoxic activity, a mouse/human chimeric 4D5 (chmAb 4D5) and a "humanized" 4D5 (rhu)mAb 4D5 HER2 antibody were constructed. Both engineered antibodies, in combination with human peripheral blood mononuclear cells, elicited antibody-dependent cytotoxic responses in accordance with the level of p185HER2 expression. Since this cytotoxic activity is independent of sensitivity to mumAb 4D5, the engineered monoclonal antibodies expand the potential target population for antibody-mediated therapy of human cancers characterized by the overexpression of p185HER2.

Targeting the function of the HER2 oncogene in human cancer therapeutics

“…HER2 oncogene in human cancer therapeutics MM Moasser were engineered for optimum participation in antibodydependent cellular cytotoxicity (ADCC) or complementdependent cytotoxicity (CDC), and indeed trastuzumab is much more efficient than its murine counterpart in mediating ADCC (Carter et al, 1992;Lewis et al, 1993;Tokuda et al, 1996). Trastuzumab has reduced cell culture antiproliferative activity compared with the murine 4D5, but equally potent antitumor efficacy in mouse xenograft models (Tokuda et al, 1996;Baselga et al, 1998;Clynes et al, 2000).…”

Recombinant humanised anti-HER2/neu antibody (Herceptin®) induces cellular death of glioblastomas

“…It derivates from a murine antibody (called 4D5 (Fendly et al, 1990;Lewis et al, 1993) and it was humanised for clinical administration. The hypervariable domain remains similar to the animal domain, but the other 95% is similar to human IgG1.…”

Differential subcellular localization, expression and biological toxicity of BRCA1 and the splice variant BRCA1-Δ11b

“…However, the entire BRCA1 protein sequence is claimed to be present in both forms based on comparisons with recombinant protein produced in vitro or in vivo. We have shown that the analysis of BRCA1 subcellular localization has been complicated by the fact that a crucial antibody (C-20, Santa Cruz) crossreacts with the epidermal growth factor receptor (EGFR) and Her2 (Wilson et al, 1996) which are frequently overexpressed in human breast and ovarian cancers and malignant cell lines (Lewis et al, 1993;Earp et al, 1995). The level of EGFR expression in the MDA-MB-468 cells used to characterize BRCA1 secretion is particularly high (Wilson et al, 1996;Filmus et al, 1985).…”