Genetically Encoded Azide Containing Amino Acid in Mammalian Cells Enables Site-Specific Antibody鈥揇rug Conjugates Using Click Cycloaddition Chemistry

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• 作者：Michael P. VanBrunt ; Kurt Shanebeck ; Zachary Caldwell ; Jeffrey Johnson ; Pamela Thompson ; Thomas Martin ; Huifang Dong ; Gary Li ; Hengyu Xu ; Francois D鈥橦ooge ; Luke Masterson ; Pauline Bariola ; Arnaud Tiberghien ; Ebele Ezeadi ; David G. Williams ; John A. Hartley ; Philip W. Howard ; Kenneth H. Grabstein ; Michael A. Bowen ; Marcello Marelli
• 刊名：Bioconjugate Chemistry
• 出版年：2015
• 出版时间：November 18, 2015
• 年：2015
• 卷：26
• 期：11
• 页码：2249-2260
• 全文大小：472K
• ISSN：1520-4812

文摘

Antibody鈥揹rug conjugates (ADC) have emerged as potent antitumor drugs that provide increased efficacy, specificity, and tolerability over chemotherapy for the treatment of cancer. ADCs generated by targeting cysteines and lysines on the antibody have shown efficacy, but these products are heterogeneous, and instability may limit their dosing. Here, a novel technology is described that enables site-specific conjugation of toxins to antibodies using chemistry to produce homogeneous, potent, and highly stable conjugates. We have developed a cell-based mammalian expression system capable of site-specific integration of a non-natural amino acid containing an azide moiety. The azide group enables click cycloaddition chemistry that generates a stable heterocyclic triazole linkage. Antibodies to Her2/neu were expressed to contain N6-((2-azidoethoxy)carbonyl)-l-lysine at four different positions. Each site allowed over 95% conjugation efficacy with the toxins auristatin F or a pyrrolobenzodiazepine (PBD) dimer to generate ADCs with a drug to antibody ratio of >1.9. The ADCs were potent and specific in in vitro cytotoxicity assays. An anti Her2/neu conjugate demonstrated stability in vivo and a PBD containing ADC showed potent efficacy in a mouse tumor xenograph model. This technology was extended to generate fully functional ADCs with four toxins per antibody. The high stability of the azide鈥揳lkyne linkage, combined with the site-specific nature of the expression system, provides a means for the generation of ADCs with optimized pharmacokinetic, biological, and biophysical properties.