The assembly of bispecific antibodies (bsAb) that retain the structure of a standard IgG can be challenging as the correct pairing of the different heavy and light chains has to be ensured while unwanted side products kept to a minimum. The use of antibodies sharing a common chain facilitates assembly of such bsAb formats but requires additional efforts during the initial discovery phase. We have developed a native bsAb format called κλ body based on antibodies that, while being specific for different antigens, share the same heavy chain. Such antibodies can readily be isolated from antibody libraries incorporating a single VH combined with light chain diversity. However, in order to improve the discovery process of such fixed VH antibodies, we developed a method to optimize populations of light chains by recovering and shuffling CDRL3 sequences that have been enriched for antigen binding by phage display selection. This approach allowed for the isolation of a more diverse and potent panel of antibodies blocking the interaction between PD-1 and PD-L1 when compared to our standard in vitro selection approach, thus providing better building blocks for subsequent bsAb generation.

中文翻译：

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改进天然双特异性抗体发现的轮次优化

保留标准 IgG 结构的双特异性抗体 (bsAb) 的组装可能具有挑战性，因为必须确保不同重链和轻链的正确配对，同时将不需要的副产物保持在最低限度。使用共享公共链的抗体有助于组装此类 bsAb 格式，但在初始发现阶段需要额外的努力。我们开发了一种称为 κλ 体的天然 bsAb 格式，其基于抗体，虽然对不同抗原具有特异性，但具有相同的重链。此类抗体可以容易地从结合了单个 VH 与轻链多样性的抗体文库中分离。然而，为了改进这种固定 VH 抗体的发现过程，我们开发了一种方法，通过回收和改组已经通过噬菌体展示选择富集抗原结合的 CDRL3 序列来优化轻链群体。与我们的标准体外选择方法相比，这种方法允许分离出更多样化和更有效的抗体组，阻断 PD-1 和 PD-L1 之间的相互作用，从而为后续的 bsAb 生成提供更好的构建模块。