Dual Function pH Responsive Bispecific Antibodies for Tumor Targeting and Antigen Depletion in Plasma
Dual Function pH Responsive Bispecific Antibodies for Tumor Targeting and Antigen Depletion in Plasma
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DOI：
10.3389/fimmu.2019.01892
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发表时间：
2019-08-09
影响因子：
7.3
通讯作者：
Kolmar, Harald
中科院分区：
文献类型：
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作者：
Bogen, Jan P.;Hinz, Steffen C.;Kolmar, Harald
膜结合的细胞表面蛋白的脱落是一种常见现象，其中细胞外结构域被释放并在循环中发现。一个突出的例子是CEACAM 5（CEA，CD 66 e），其中脱落结构域在肿瘤进展和转移中起关键作用。对于实体瘤的治疗，血浆中肿瘤特异性抗原的存在可能是有问题的，因为肿瘤特异性抗体可能在侵入其期望的肿瘤靶区域之前被可溶性抗原拦截。为了克服这个问题，我们开发了产生双特异性抗体的通用程序，其中一个臂以pH依赖性方式结合抗原，从而增强内体摄取后的抗原清除，而另一个臂能够不依赖于pH靶向肿瘤细胞。这通过将pH敏感性结合模式并入仅结合CEACAM 5重链的抗体的共同轻链IGKV 3 -15*01中来实现。使用酵母表面展示筛选组氨酸掺杂的轻链文库使得能够分离pH依赖性结合剂。当这样的轻链用作双特异性抗体形式中的共同轻链时，只有在选择期间鉴定的相应重链/轻链组合显示pH响应性结合。此外，我们发现改变的共同轻链不会负面影响其他仅重链结合物对其各自抗原的亲和力。我们的策略可能为产生双特异性开辟新的途径，其中一个臂有效地从循环中去除脱落抗原，而另一个臂以pH非依赖性方式靶向肿瘤标志物。
Shedding of membrane-bound cell surface proteins, where the extracellular domain is released and found in the circulation is a common phenomenon. A prominent example is CEACAM5 (CEA, CD66e), where the shed domain plays a pivotal role in tumor progression and metastasis. For treatment of solid tumors, the presence of the tumor-specific antigen in the plasma can be problematic since tumor-specific antibodies might be intercepted by the soluble antigen before invading their desired tumor target area. To overcome this problem, we developed a generic procedure to generate bispecific antibodies, where one arm binds the antigen in a pH-dependent manner thereby enhancing antigen clearance upon endosomal uptake, while the other arm is able to target tumor cells pH-independently. This was achieved by incorporating pH-sensitive binding modalities in the common light chain IGKV3-15*01 of a CEACAM5 binding heavy chain only antibody. Screening of a histidine-doped light chain library using yeast surface display enabled the isolation of pH-dependent binders. When such a light chain was utilized as a common light chain in a bispecific antibody format, only the respective heavy/light chain combination, identified during selections, displayed pH-responsive binding. In addition, we found that the altered common light chain does not negatively impact the affinity of other heavy chain only binders toward their respective antigen. Our strategy may open new avenues for the generation of bispecifics, where one arm efficiently removes a shed antigen from the circulation while the other arm targets a tumor marker in a pH-independent manner.