Application of Strain-Promoted Azide鈥揂lkyne Cycloaddition and Tetrazine Ligation to Targeted Fc-Drug Conjugates

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• 作者：Joshua D. Thomas ; Huiting Cui ; Patrick ; J. North ; Thomas Hofer ; Christoph Rader ; Terrence R. Burke ; Jr.
• 刊名：Bioconjugate Chemistry
• 出版年：2012
• 出版时间：October 17, 2012
• 年：2012
• 卷：23
• 期：10
• 页码：2007-2013
• 全文大小：428K
• 年卷期：v.23,no.10(October 17, 2012)
• ISSN：1520-4812

文摘

We have previously described an approach whereby antibody Fc fragments harboring a single C-terminal selenocysteine residue (Fc-Sec) are directed against a variety of targets by changing the peptide or small molecule to which they are conjugated. In the present work, we describe methodology for improving the efficacy of these Fc-Sec conjugates by incorporating cytotoxic drugs. The Fc-Sec protein is first programmed to target specific tumor cell types by attachment of a bifunctional linker that contains a 鈥渃lickable鈥?handle (e.g., cyclobutane or cyclooctyne) in addition to a tumor cell-binding peptide or small molecule. Following Fc-Sec conjugation, a cytotoxic warhead is then attached by cycloaddition reactions of tetrazine or azide-containing linker. To validate this approach, we used a model system in which folic acid (FA) is the targeting moiety and a disulfide-linked biotin moiety serves as a cytotoxic drug surrogate. We demonstrated successful targeting of Fc-Sec proteins to folate-receptor expressing tumor cells. Tetrazine ligation was found to be an efficient method for biotin 鈥渁rming鈥?of the folate-targeted Fc-Sec proteins. We also report novel bioconjugation methodologies that use [4 + 2] cycloaddition reactions between tetrazines and cyclooctynes.