Xencor, Inc., Monrovia, CA, United States.
Xencor, Inc., Monrovia, CA, United States.
Methods. 2019 Feb 1;154:38-50. doi: 10.1016/j.ymeth.2018.10.006. Epub 2018 Oct 23.
Bispecific monoclonal antibodies can bind two protein targets simultaneously and enable therapeutic modalities inaccessible by traditional mAbs. Bispecific formats containing a heterodimeric Fc region are of particular interest, as a heterodimeric Fc empowers both bispecificity and altered valencies while retaining the developability and druggability of a monoclonal antibody. We present a robust heterodimeric Fc platform, called the XmAb® bispecific platform, engineered for efficient development of bispecific antibodies and Fc fusions of multiple formats. First, we engineer a purification solution for proteins containing a heterodimeric Fc using engineered isoelectric point differences in the Fc region that enable straightforward purification of the heterodimeric species. Then, we combine this purification solution with a novel set of Fc substitutions capable of achieving heterodimer yields over 95% with little change in thermostability. Next, we illustrate the flexibility of our heterodimeric Fc with a case study in which a wide range of tumor-associated antigen × CD3 bispecifics are generated, differing in choice of tumor antigen, affinities for both tumor antigen and CD3, and tumor antigen valency. Finally, we present manufacturing data reinforcing the robustness of the heterodimeric Fc platform at scale.
双特异性单克隆抗体可以同时结合两个蛋白靶点，并使传统单克隆抗体无法实现的治疗方式成为可能。含有异二聚体 Fc 区的双特异性形式特别有趣，因为异二聚体 Fc 既能赋予双特异性，又能改变价态，同时保留单克隆抗体的可开发性和可用药性。我们提出了一个强大的异二聚体 Fc 平台，称为 XmAb®双特异性平台，专为高效开发双特异性抗体和多种形式的 Fc 融合物而设计。首先，我们使用 Fc 区域中的工程等电点差异为含有异二聚体 Fc 的蛋白质设计了一种纯化解决方案，这使得异二聚体物种的纯化变得简单。然后，我们将这种纯化解决方案与一组新的 Fc 取代结合使用，这些取代能够实现异二聚体产率超过 95%，而热稳定性的变化很小。接下来，我们通过一个案例研究说明了我们的异二聚体 Fc 的灵活性，该案例研究中生成了广泛的肿瘤相关抗原×CD3 双特异性抗体，其在肿瘤抗原的选择、对肿瘤抗原和 CD3 的亲和力以及肿瘤抗原价态方面存在差异。最后，我们提供了制造数据，证明了异二聚体 Fc 平台在大规模生产中的稳健性。
