Antibody-maytansinoid conjugates are activated in targeted cancer cells by lysosomal degradation and linker-dependent intracellular processing
Antibody-maytansinoid conjugates are activated in targeted cancer cells by lysosomal degradation and linker-dependent intracellular processing
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DOI：
10.1158/0008-5472.can-05-4489
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发表时间：
2006-04-15
期刊：
影响因子：
11.2
通讯作者：
Blättler, WA
中科院分区：
文献类型：
--
作者：
Erickson, HK;Park, PU;Blättler, WA
抗体-药物结合物是一种靶向抗癌药物，由一种细胞毒药物共价连接到一种具有肿瘤抗原特异性活性的单抗上。一旦与靶细胞表面抗原结合，必须对结合物进行处理，以释放药物的一种活性形式，从而达到细胞内的目标。在这里，我们使用了生物学和生物化学的方法来更好地定义抗体-美丹素结合物的这一过程。特别是，我们研究了含有二硫键连接物(huC242-SPDB-dm4)或硫醚修补剂(huC242-SMCC-DM1)的huC242-美丹素结合物在细胞中的代谢命运。结合细胞周期分析和溶酶体抑制剂，我们发现，无论连接物是什么，抗体-蛋氨酸偶联物的活性都需要溶酶体处理。我们还鉴定和表征了从这些结合物中释放的美丹素分子，并测量了它们的释放速率，与细胞周期停滞的动力学进行了比较。这两种结合物在溶酶体中被有效地降解，以产生由完整的美坦辛药物和连接到赖氨酸上的连接物组成的代谢物。赖氨酸加合物是硫醚连接的结合物的唯一代谢物。然而，从二硫键连接的偶联物产生的赖氨酸代谢物被还原并被S甲基化，以产生亲脂和有效的细胞毒性代谢物S-甲基-DM4。这些发现提供了对抗体-蛋氨酸结合物作用机制的一般洞察，更具体地说，确定了可能解释二硫键连接的结合物显著增强抗肿瘤疗效的生化机制。
Antibody-drug conjugates are targeted anticancer agents consisting of a cytotoxic drug covalently linked to a monoclonal antibody for tumor antigen-specific activity. Once bound to the target cell-surface antigen, the conjugate must be processed to release an active form of the drug, which can reach its intracellular target. Here, we used both biological and biochemical methods to better define this process for antibody-maytansinoid conjugates. In particular, we examined the metabolic fate in cells of huC242-maytansinoid conjugates containing either a disulfide linker (huC242-SPDB-DM4) or a thioether tinker (huC242-SMCC-DM1). Using cell cycle analysis combined with lysosomal inhibitors, we showed that lysosomal processing is required for the activity of anti body-maytansinoid conjugates, irrespective of the linker. We also identified and characterized the released maytansinoid molecules from these conjugates, and measured their rate of release compared with the kinetics of cell cycle arrest. Both conjugates are efficiently degraded in lysosomes to yield metabolites consisting of the intact maytansinoid drug and linker attached to lysine. The lysine adduct is the sole metabolite from the thioether-linked conjugate. However, the lysine metabolite generated from the disulfide-linked conjugate is reduced and S-methylated to yield the lipophilic and potently cytotoxic metabolite, S-methyl-DM4. These findings provide insight into the mechanism of action of antibody-maytansinoid conjugates in general, and more specifically, identify a biochemical mechanism that may account for the significantly enhanced antitumor efficacy observed with disulfide-linked conjugates.