作者:Brendon E. Cook、Rosemery Membreno、Brian M. Zeglis
DOI:10.1021/acs.bioconjchem.8b00385
日期:2018.8.15
The development of immunoconjugates requires a careful balance between preserving the functionality of the antibody and modifying the immunoglobulin with the desired cargo. Herein, we describe the synthesis, development, and in vivo evaluation of a novel bifunctional dendrimeric scaffold and its application in pretargeted PET imaging. The site-specific modification of the huA33 antibody with this dendrimeric scaffold yields an immunoconjugate—sshuA33-DEN-TCO—decorated with ∼8 trans-cyclooctene (TCO) moieties, a marked increase compared to the ∼2 TCO/mAb of a nondendrimeric control immunoconjugate (sshuA33-PEG12-TCO). Pretargeted PET imaging and biodistribution experiments were used to compare the in vivo performance of these two immunoconjugates in athymic nude mice bearing subcutaneous SW1222 human colorectal cancer xenografts. To this end, the mice were administered 100 μg of each immunoconjugate followed 120 h later by the injection of a tetrazine-bearing radioligand, [64Cu]Cu-SarAr-Tz. Pretargeting with sshuA33-DEN-TCO produced excellent tumoral uptake at 24 h (8.9 ± 1.9 %ID/g), more than double that created by sshuA33-PEG12-TCO (4.1 ± 1.3 %ID/g). Critically—and somewhat surprisingly—the attachment of the G0.5 dendrimeric structures did not hamper the in vivo behavior of the immunoconjugate, suggesting that this versatile bifunctional scaffold may have applications beyond pretargeting.
免疫结合剂的开发需要在保持抗体的功能性和用所需载体修饰免疫球蛋白之间取得谨慎的平衡。在本文中,我们介绍了一种新型双功能树枝状分子支架的合成、开发和体内评估及其在正电子发射计算机断层显像前的应用。用这种树状分子支架对 huA33 抗体进行位点特异性修饰后,免疫结合物-sshuA33-DEN-TCO-被装饰了 8 个反式环辛烯(TCO)分子,与非树状分子对照免疫结合物(sshuA33-PEG12-TCO)的 2 个 TCO/mAb 相比,有了明显增加。在皮下注射了 SW1222 人结肠直肠癌异种移植物的无胸腺裸鼠体内进行了 PET 预定位成像和生物分布实验,以比较这两种免疫轭合物的体内表现。为此,先给小鼠注射每种免疫结合剂 100 μg,120 小时后再注射含有四嗪的放射性配体 [64Cu]Cu-SarAr-Tz。用 sshuA33-DEN-TCO 进行预定位在 24 小时后产生了极好的肿瘤摄取率(8.9 ± 1.9 %ID/g),是 sshuA33-PEG12-TCO 产生的摄取率(4.1 ± 1.3 %ID/g)的两倍多。令人惊讶的是,G0.5 树枝状结构的附着并没有影响免疫共轭物在体内的表现,这表明这种多功能双功能支架的应用可能超出了预靶向的范围。