This communication describes the design, synthesis and biological activity of a megamolecule mimic of an anti-HER2 antibody. The antibody mimic was prepared by linking two Fabs from the therapeutic antibody trastuzumab, which are fused through the heavy chain variable domain to either cutinase or SnapTag, with a linker terminated in an irreversible inhibitor for each enzyme. This mimic binds HER2 with comparable avidity to trastuzumab, has similar activity in a cell-based assay, and can arrest tumor growth in a mouse xenograft BT474 tumor model. A panel of 16 bivalent anti-HER2 antibodies were prepared wherein each varied in the orientation of the fusion domain on the Fabs. The analogs displayed a range of cytotoxic activity and surprisingly, the most active mimic binds to cells with a ten-fold lower avidity than the least active variant suggesting that structure plays a large role in their efficacy. This work suggests that the megamolecule approach can be used to prepare antibody mimics having a broad structural diversity.

中文翻译：

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治疗性抗体的大分子模拟物的设计和合成

本通讯描述了抗 HER2 抗体的大分子模拟物的设计、合成和生物活性。抗体模拟物是通过连接来自治疗性抗体曲妥珠单抗的两个 Fab 来制备的，这些 Fab 通过重链可变域与角质酶或 SnapTag 融合，每个酶的不可逆抑制剂中都有一个接头。这种模拟物以与曲妥珠单抗相当的亲和力结合 HER2，在基于细胞的测定中具有相似的活性，并且可以在小鼠异种移植 BT474 肿瘤模型中阻止肿瘤生长。制备了一组 16 个二价抗 HER2 抗体，其中每个抗体在 Fab 上融合域的方向不同。类似物显示出一系列细胞毒活性，令人惊讶的是，最活跃的模拟物以比最不活跃的变体低十倍的亲和力与细胞结合，这表明该结构在其功效中起着重要作用。这项工作表明大分子方法可用于制备具有广泛结构多样性的抗体模拟物。