Department of Drug Metabolism and Pharmacokinetics, AbbVie, Inc., North Chicago, Illinois.
Process R&D Department, AbbVie, Inc., North Chicago, Illinois.
Mol Cancer Ther. 2018 Jun;17(6):1341-1351. doi: 10.1158/1535-7163.MCT-17-0672. Epub 2018 Mar 28.
Antibody-drug conjugates (ADC) offer an avenue for specific drug delivery to target cells. Here, parameters with important roles in the cellular processing of ADCs were quantitatively measured for Ab033, an antibody against EGFR. In EGFR-overexpressing cancer cell lines, Ab033 internalized at rates of 0.047/min and 0.15/min for A431 and H441 cells, respectively. Once internalized, Ab033 either trafficked to the lysosome or was recycled; up to 45% of internalized Ab033 returned to the cell surface. Despite such recycling, intracellular accumulation of Ab033 continually increased over 24 hours. Ab033 was conjugated to form a dual toxin ADC containing both cleavable and non-cleavable linker-drug payloads for release rate comparisons. Intracellular concentrations of freed drug from cleavable linker were greater than from non-cleavable linker and exceeded 5 × 10 drug molecules per A431 cell after 24 hours. Compared with intracellular antibody accumulation, formation of released drug was delayed, likely due to the time needed for endo-lysosomal trafficking and subsequent linker/antibody proteolysis. Informed by the quantitative data, a cellular ADC model was constructed and used to summarize processing inefficiencies. Modeling simulations were conducted to determine parameter sensitivity on intracellular drug concentrations, with rates of EGFR internalization and recycling as well as ADC trafficking found to be the most sensitive toward final intracellular drug concentrations. Overall, this study shows Ab033 ADCs to be a viable strategy for delivery of cytotoxic drugs into tumor cells with subsequent modeling efforts able to highlight key processing steps to be improved for increased drug delivery. .
抗体药物偶联物（ADC）为靶向细胞的特异性药物递送提供了一种途径。在这里，定量测量了针对 EGFR 的抗体 Ab033 的细胞内处理中具有重要作用的参数。在 EGFR 过表达的癌细胞系中，Ab033 的内化速率分别为 A431 和 H441 细胞的 0.047/min 和 0.15/min。一旦内化，Ab033 要么转运到溶酶体，要么被回收；多达 45%的内化 Ab033 回到细胞表面。尽管有这种回收，Ab033 的细胞内积累在 24 小时内仍持续增加。Ab033 被共轭形成含有可切割和不可切割连接子-药物有效载荷的双重毒素 ADC，用于释放率比较。从可切割连接子释放的游离药物的细胞内浓度大于从不可切割连接子的释放浓度，并且在 24 小时后超过每个 A431 细胞 5×10 个药物分子。与细胞内抗体积累相比，释放药物的形成被延迟，可能是由于需要内体溶酶体运输和随后的连接子/抗体蛋白水解的时间。根据定量数据，构建了细胞 ADC 模型并用于总结处理效率低下。进行了建模模拟以确定细胞内药物浓度的参数敏感性，发现 EGFR 内化和回收以及 ADC 转运的速率对最终细胞内药物浓度最敏感。总体而言，这项研究表明 Ab033 ADC 是将细胞毒性药物递送到肿瘤细胞的可行策略，随后的建模工作能够突出需要改进的关键处理步骤，以提高药物递送效率。
