Two mechanisms of the enhanced antibody-dependent cellular cytotoxicity (ADCC) efficacy of non-fucosylated therapeutic antibodies in human blood.
Two mechanisms of the enhanced antibody-dependent cellular cytotoxicity (ADCC) efficacy of non-fucosylated therapeutic antibodies in human blood.
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DOI：
10.1186/1471-2407-9-58
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发表时间：
2009-02-18
期刊：
影响因子：
3.8
通讯作者：
Satoh M
中科院分区：
文献类型：
--
作者：
Iida S;Kuni-Kamochi R;Mori K;Misaka H;Inoue M;Okazaki A;Shitara K;Satoh M
抗体依赖性细胞毒性（Antibody-dependent cellular cytotoxicity， ADCC）最近被认为是影响治疗性抗体，尤其是抗癌抗体临床疗效的关键机制之一。研究发现，完全缺乏Fc低聚糖核心焦点的治疗性抗体在人类中表现出比其聚焦对应物高得多的ADCC。然而，显示完全非聚焦抗体如何在人全血中达到如此高的ADCC的数据尚未披露。完全非聚焦性治疗性抗体介导的高ADCC的确切机制，即使在人血浆中也存在，应该基于人血液中非聚焦性抗体作用的直接证据来解释。利用非聚焦和聚焦抗cd20 IgG1s利妥昔单抗的人体外b细胞消耗试验，我们监测了治疗药物与靶细胞上抗原（靶侧相互作用）和效应细胞上白细胞受体（FcγR）的结合（效应侧相互作用），比较了人血液中ADCC的强度。在靶侧相互作用中，未观察到抗CD20介导的CD20对B细胞的下调。在人血液中检测到聚焦型和非聚焦型抗cd20与靶B细胞抗原结合的简单竞争，从而抑制非聚焦型抗cd20增强的ADCC。在效应副相互作用中，非聚焦的抗cd20显示出足够高的FcγRIIIa结合活性，以克服血浆IgG在自然杀伤细胞（NK）上与FcγRIIIa结合的竞争，而聚焦的抗cd20与FcγRIIIa的结合在人血浆存在下几乎被消除，无法有效招募NK细胞。健康供体个体血清IgG1的核心聚焦水平存在微小差异，因此不会影响聚焦抗cd20对ADCC的抑制作用。我们的研究结果表明，从抗体疗法中去除集中的抗体成分通过两种机制引起人血液中的高ADCC：即，通过逃避血浆IgG对FcγRIIIa结合（效应侧相互作用）和集中抗体对抗原结合（靶侧相互作用）的抑制作用。
Antibody-dependent cellular cytotoxicity (ADCC) has recently been identified as one of the critical mechanisms underlying the clinical efficacy of therapeutic antibodies, especially anticancer antibodies. Therapeutic antibodies fully lacking the core fucose of the Fc oligosaccharides have been found to exhibit much higher ADCC in humans than their fucosylated counterparts. However, data which show how fully non-fucosylated antibodies achieve such a high ADCC in human whole blood have not yet been disclosed. The precise mechanisms responsible for the high ADCC mediated by fully non-fucosylated therapeutic antibodies, even in the presence of human plasma, should be explained based on direct evidence of non-fucosylated antibody action in human blood. Using a human ex vivo B-cell depletion assay with non-fucosylated and fucosylated anti-CD20 IgG1s rituximab, we monitored the binding of the therapeutic agents both to antigens on target cells (target side interaction) and to leukocyte receptors (FcγR) on effector cells (effector side interaction), comparing the intensities of ADCC in human blood. In the target side interaction, down-modulation of CD20 on B cells mediated by anti-CD20 was not observed. Simple competition for binding to the antigens on target B cells between fucosylated and non-fucosylated anti-CD20s was detected in human blood to cause inhibition of the enhanced ADCC of non-fucosylated anti-CD20 by fucosylated anti-CD20. In the effector side interaction, non-fucosylated anti-CD20 showed sufficiently high FcγRIIIa binding activity to overcome competition from plasma IgG for binding to FcγRIIIa on natural killer (NK) cells, whereas the binding of fucosylated anti-CD20 to FcγRIIIa was almost abolished in the presence of human plasma and failed to recruit NK cells effectively. The core fucosylation levels of individual serum IgG1 from healthy donors was found to be so slightly different that it did not affect the inhibitory effect on the ADCC of fucosylated anti-CD20. Our results demonstrate that removal of fucosylated antibody ingredients from antibody therapeutics elicits high ADCC in human blood by two mechanisms: namely, by evading the inhibitory effects both of plasma IgG on FcγRIIIa binding (effector side interaction) and of fucosylated antibodies on antigen binding (target side interaction).