Engineering an IgG Scaffold Lacking Effector Function with Optimized Developability
Engineering an IgG Scaffold Lacking Effector Function with Optimized Developability
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DOI：
10.1074/jbc.m116.748525
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发表时间：
2017-02-03
影响因子：
4.8
通讯作者：
Gunasekaran, Kannan
中科院分区：
文献类型：
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作者：
Jacobsen, Frederick W.;Stevenson, Riki;Gunasekaran, Kannan
IgG同型可以不同地与Fc受体和补体结合，这使得选择哪种同型来开发特定的治疗性抗体对于确定药物的安全性和有效性非常重要。IgG2和IgG4同型对Fc受体的结合亲和力显著降低。最近的证据表明，IgG2同型并非完全没有效应功能，而IgG4同型可以在体内进行Fab臂交换，从而产生双特异性抗体和脱靶效应。本研究尝试设计一种基于IgG1的支架，该支架缺乏效应功能，但具有与母体IgG1相当的稳定性。注意确保以最少的突变数实现稳定性和缺乏效应功能。在Asn（297）突变体中，我们发现N297G突变体比N297Q或N297A突变体具有更好的稳定性和可发展性。为了进一步提高N297G的稳定性，我们在CH2结构域溶剂不可接近的位置引入了一种新的工程二硫键。所得支架的稳定性大于或等于亲本IgG1支架。在小鼠、大鼠和猴子身上进行的广泛的生物物理分析和药代动力学（PK）研究进一步证实了这种独特支架的可发展性，并表明它可用于所有需要缺乏效应功能或消除与Fc受体结合的含Fc的治疗药物（例如抗体、双特异性抗体和Fc融合物）。
IgG isotypes can differentially bind to Fc receptors and complement, making the selection of which isotype to pursue for development of a particular therapeutic antibody important in determining the safety and efficacy of the drug. IgG2 and IgG4 isotypes have significantly lower binding affinity to Fc receptors. Recent evidence suggests that the IgG2 isotype is not completely devoid of effector function, whereas the IgG4 isotype can undergo in vivo Fab arm exchange leading to bispecific antibody and off-target effects. Here an attempt was made to engineer an IgG1-based scaffold lacking effector function but with stability equivalent to that of the parent IgG1. Care was taken to ensure that both stability and lack of effector function was achieved with a minimum number of mutations. Among the Asn(297) mutants that result in lack of glycosylation and thus loss of effector function, we demonstrate that the N297G variant has better stability and developability compared with the N297Q or N297A variants. To further improve the stability of N297G, we introduced a novel engineered disulfide bond at a solvent inaccessible location in the CH2 domain. The resulting scaffold has stability greater than or equivalent to that of the parental IgG1 scaffold. Extensive biophysical analyses and pharmacokinetic (PK) studies in mouse, rat, and monkey further confirmed the developability of this unique scaffold, and suggest that it could be used for all Fc containing therapeutics (e.g. antibodies, bispecific antibodies, and Fc fusions) requiring lack of effector function or elimination of binding to Fc gamma receptors.