Engineering the Human Fc Region Enables Direct Cell Killing by Cancer Glycan-Targeting Antibodies without the Need for Immune Effector Cells or Complement.
Engineering the Human Fc Region Enables Direct Cell Killing by Cancer Glycan-Targeting Antibodies without the Need for Immune Effector Cells or Complement.
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DOI：
10.1158/0008-5472.can-19-3599
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发表时间：
2020-08-15
期刊：
影响因子：
11.2
通讯作者：
Durrant LG
中科院分区：
文献类型：
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作者：
Vankemmelbeke M;McIntosh RS;Chua JX;Kirk T;Daniels I;Patsalidou M;Moss R;Parsons T;Scott D;Harris G;Ramage JM;Spendlove I;Durrant LG
鼠IgG 3聚糖靶向mAb通常在不存在免疫效应细胞或补体的情况下通过类似肿瘤坏死的促炎机制诱导直接细胞杀伤。这种癌细胞杀伤是由于相邻抗体的Fc区之间的非共价缔合，导致亲和力增强。人同种型不含这种协同结合模式下的残基;因此，小鼠IgG 3 mAb的直接细胞杀伤在嵌合或人源化后丧失。使用Lewisa/c/x -靶向88 mAb，我们鉴定了直接细胞杀伤和增加亲合力的鼠IgG 3残基，其通过一系列恒定区改组和亚结构域交换方法产生体外和体内具有增强的肿瘤杀伤的改进的（“i”）嵌合mAb。恒定区改组确定了主要的CH 3和次要的CH 2贡献，其进一步映射到残基286-306和339-378之间的不连续区域，当引入88 hIgG 1时，再现了88 mIgG 3的直接细胞杀伤和亲合力。更令人感兴趣的是通过将这些选择的残基引入129 hIgG 1中，将其转化为具有增强的亲合力和显著的体内肿瘤控制的直接细胞杀伤mAb，从而产生唾液酸-二-Lewisa -靶向i129 G1 mAb。人iG 1 mAb（称为Avidimabs）保留了效应子功能，为促炎性直接细胞杀伤铺平了道路，从而通过缓解免疫抑制促进ADCC和CDC。最终，人聚糖靶向IgG 1 mAb的Fc工程赋予了促炎性直接细胞杀伤和增强的亲合力，这种方法可用于改善具有治疗潜力的其他mAb的亲合力。
Murine IgG3 glycan-targeting mAb often induces direct cell killing in the absence of immune effector cells or complement via a proinflammatory mechanism resembling oncotic necrosis. This cancer cell killing is due to non-covalent association between Fc regions of neighboring antibodies, resulting in enhanced avidity. Human isotypes do not contain the residues underlying this cooperative binding mode; consequently, the direct cell killing of mouse IgG3 mAb is lost upon chimerization or humanization. Using the Lewisa/c/x -targeting 88mAb, we identified the murine IgG3 residues underlying the direct cell killing and increased avidity via a series of constant region shuffling and subdomain swapping approaches to create improved (‘i’) chimeric mAb with enhanced tumor killing in vitro and in vivo. Constant region shuffling identified a major CH3 and a minor CH2 contribution, which was further mapped to discontinuous regions among residues 286-306 and 339-378 that, when introduced in 88hIgG1, recapitulated the direct cell killing and avidity of 88mIgG3. Of greater interest was the creation of a sialyl-di-Lewisa -targeting i129G1 mAb via introduction of these selected residues into 129hIgG1, converting it into a direct cell killing mAb with enhanced avidity and significant in vivo tumor control. The human iG1 mAb, termed Avidimabs, retained effector functions, paving the way for the proinflammatory direct cell killing to promote ADCC and CDC through relief of immunosuppression. Ultimately, Fc engineering of human glycan-targeting IgG1 mAb confers proinflammatory direct cell killing and enhanced avidity, an approach that could be used to improve the avidity of other mAb with therapeutic potential.