Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK.
Program of Immunology and Immunotherapy, CIMA, Universidad de Navarra, Pamplona, Spain; Navarra Institute for Health Research (IDISNA), Pamplona, Spain.
J Biol Chem. 2022 Aug;298(8):102153. doi: 10.1016/j.jbc.2022.102153. Epub 2022 Jun 16.
The generation of bispecific antibodies (bsAbs) targeting two different antigens opens a new level of specificity and, compared to mAbs, improved clinical efficacy in cancer therapy. Currently, the different strategies for development of bsAbs primarily focus on IgG isotypes. Nevertheless, in comparison to IgG isotypes, IgE has been shown to offer superior tumor control in preclinical models. Therefore, in order to combine the promising potential of IgE molecules with increased target selectivity of bsAbs, we developed dual tumor-associated antigen-targeting bispecific human IgE antibodies. As proof of principle, we used two different pairing approaches - knobs-into-holes and leucine zipper-mediated pairing. Our data show that both strategies were highly efficient in driving bispecific IgE formation, with no undesired pairings observed. Bispecific IgE antibodies also showed a dose-dependent binding to their target antigens, and cell bridging experiments demonstrated simultaneous binding of two different antigens. As antibodies mediate a major part of their effector functions through interaction with Fc receptors (FcRs) expressed on immune cells, we confirmed FcεR binding by inducing in vitro mast cell degranulation and demonstrating in vitro and in vivo monocyte-mediated cytotoxicity against target antigen-expressing Chinese hamster ovary cells. Moreover, we demonstrated that the IgE bsAb construct was significantly more efficient in mediating antibody-dependent cell toxicity than its IgG1 counterpart. In conclusion, we describe the successful development of first bispecific IgE antibodies with superior antibody-dependent cell toxicity-mediated cell killing in comparison to IgG bispecific antibodies. These findings highlight the relevance of IgE-based bispecific antibodies for clinical application.
针对两种不同抗原的双特异性抗体（bsAbs）的产生开辟了一个新的特异性水平，与单克隆抗体（mAbs）相比，在癌症治疗中提高了临床疗效。目前，bsAbs 的不同开发策略主要集中在 IgG 同型上。然而，与 IgG 同型相比，IgE 在临床前模型中已被证明具有更好的肿瘤控制作用。因此，为了将 IgE 分子的有前途的潜力与 bsAbs 的更高靶向选择性相结合，我们开发了靶向两种肿瘤相关抗原的双特异性人 IgE 抗体。作为原理验证，我们使用了两种不同的配对方法 - 旋钮入孔和亮氨酸拉链介导的配对。我们的数据表明，这两种策略都非常有效地驱动了双特异性 IgE 的形成，没有观察到不需要的配对。双特异性 IgE 抗体也表现出对其靶抗原的剂量依赖性结合，并且细胞桥接实验证明了两种不同抗原的同时结合。由于抗体通过与表达在免疫细胞上的 Fc 受体（FcRs）相互作用介导其大部分效应功能，我们通过诱导体外肥大细胞脱颗粒并证明体外和体内单核细胞介导对表达靶抗原的中国仓鼠卵巢细胞的细胞毒性来证实 FcεR 结合。此外，我们证明了与 IgG1 相比，IgE bsAb 构建体在介导抗体依赖性细胞毒性方面更有效。总之，我们描述了首例成功开发的双特异性 IgE 抗体，与 IgG 双特异性抗体相比，其具有更好的抗体依赖性细胞毒性介导的细胞杀伤作用。这些发现强调了 IgE 为基础的双特异性抗体在临床应用中的相关性。
