Division of Stem Cell Transplantation and Immunotherapy, 2nd Department of Medicine, Christian-Albrechts-University, Kiel, Germany.
J Immunol Methods. 2011 Aug 31;371(1-2):122-33. doi: 10.1016/j.jim.2011.06.023. Epub 2011 Jun 30.
Antibody-drug conjugates (ADC) represent promising agents for targeted cancer therapy. To allow rational selection of human antibodies with favorable characteristics for ADC development a screening tool was designed obviating the need of preparing individual covalently linked conjugates. Therefore, α-kappa-ETA' was designed as a fusion protein consisting of a human kappa light chain binding antibody fragment and a truncated version of Pseudomonas exotoxin A. α-kappa-ETA' specifically bound to human kappa light chains of human or human-mouse chimeric antibodies and Fab fragments. Antibody-redirected α-kappa-ETA' specifically inhibited proliferation of antigen-expressing cell lines at low toxin and antibody concentrations. Selected antibodies that efficiently delivered α-kappa-ETA' in the novel assay system were used to generate scFv-based covalently linked immunotoxins. These molecules efficiently triggered apoptosis of target cells, indicating that antibodies identified in our assay system can be converted to functional immunoconjugates. Finally, a panel of human epidermal growth factor receptor (EGFR) antibodies was screened--demonstrating favorable characteristics with antibody 2F8. These data suggest that antibodies with potential for Pseudomonas exotoxin A-based ADC development can be identified using the novel α-kappa-ETA' conjugate.
抗体药物偶联物（ADC）是一种有前途的靶向癌症治疗药物。为了能够合理选择对 ADC 开发具有有利特性的人源抗体，设计了一种筛选工具，该工具避免了制备单个共价连接偶联物的需要。因此，设计了 α-κ-ETA'作为一种融合蛋白，由与人κ轻链结合的抗体片段和假单胞菌外毒素 A 的截断版本组成。α-κ-ETA'特异性结合人源或人源嵌合抗体和 Fab 片段的 κ 轻链。抗体导向的 α-κ-ETA'在低毒素和抗体浓度下特异性抑制表达抗原的细胞系的增殖。在新型测定系统中有效递送 α-κ-ETA'的选定抗体被用于生成 scFv 为基础的共价连接免疫毒素。这些分子有效地引发靶细胞凋亡，表明在我们的测定系统中鉴定的抗体可以转化为功能性免疫偶联物。最后，筛选了一组人表皮生长因子受体（EGFR）抗体——抗体 2F8 表现出良好的特性。这些数据表明，使用新型 α-κ-ETA'缀合物可以鉴定出具有假单胞菌外毒素 A 为基础的 ADC 开发潜力的抗体。
