Shalaby M R, Shepard H M, Presta L, Rodrigues M L, Beverley P C, Feldmann M, Carter P
Department of Cell Biology, Genentech, Inc., South San Francisco, California 94080.
J Exp Med. 1992 Jan 1;175(1):217-25. doi: 10.1084/jem.175.1.217.
The HER2 protooncogene encodes a 185-kD transmembrane phosphoglycoproteins, human epidermal growth factor receptor 2 (p185HER2), whose amplified expression on the cell surface can lead to malignant transformation. Overexpression of HER2/p185HER2 is strongly correlated with progression of human ovarian and breast carcinomas. Recent studies have shown that human T cells can be targeted with bispecific antibody to react against human tumor cells in vitro. We have developed a bispecific F(ab')2 antibody molecule consisting of a humanized arm with a specificity to p185HER2 linked to another arm derived from a murine anti-CD3 monoclonal antibody that we have cloned from UCHT1 hybridoma. The antigen-binding loops for the anti-CD3 were installed in the context of human variable region framework residues, thus forming a fully humanized BsF(ab')2 fragment. Additional variants were produced by replacement of amino acid residues located in light chain complementarity determining region 2 and heavy chain framework region 3 of the humanized anti-CD3 arm. Flow cytometry analysis showed that the bispecific F(ab')2 molecules can bind specifically to cells overexpressing p185HER2 and to normal human peripheral blood mononuclear cells bearing the CD3 surface marker. In additional experiments, the presence of bispecific F(ab')2 caused up to fourfold enhancement in the cytotoxic activities of human T cells against tumor cells overexpressing p185HER2 as determined by a 51Cr release assay. These bispecific molecules have a potential use as therapeutic agents for the treatment of cancer.
HER2原癌基因编码一种185-kD跨膜磷酸糖蛋白，即人表皮生长因子受体2（p185HER2），其在细胞表面的扩增表达可导致恶性转化。HER2/p185HER2的过表达与人类卵巢癌和乳腺癌的进展密切相关。最近的研究表明，人T细胞可被双特异性抗体靶向，从而在体外与人类肿瘤细胞发生反应。我们开发了一种双特异性F(ab')2抗体分子，它由一个对p185HER2具有特异性的人源化臂与另一个源自我们从UCHT1杂交瘤克隆的鼠抗CD3单克隆抗体的臂连接而成。抗CD3的抗原结合环被安装在人可变区框架残基的背景下，从而形成一个完全人源化的BsF(ab')2片段。通过替换人源化抗CD3臂的轻链互补决定区2和重链框架区3中的氨基酸残基产生了其他变体。流式细胞术分析表明，双特异性F(ab')2分子可特异性结合过表达p185HER2的细胞以及带有CD3表面标志物的正常人外周血单个核细胞。在另外的实验中，通过51Cr释放试验测定，双特异性F(ab')2的存在使人类T细胞对过表达p185HER2的肿瘤细胞的细胞毒活性增强了多达四倍。这些双特异性分子有作为癌症治疗药物的潜在用途。
