新型双特异纳米抗体的研制

抗体介导的肿瘤免疫治疗在临床上取得了显著成效，而且我们参与研发的国际上首个靶向PD-L1的纳米抗体KN035以及靶向CTLA-4的纳米抗体KN044也已经进入临床试验。我们前期针对KN035/PD-L1和KN044/CTLA-4复合物晶体结构的研究揭示，KN035主要通过纳米抗体表面较长的CDR3片段结合PD-L1，而KN044主要通过CDR1和CDR2片段识别CTLA-4。通过简单嫁接CDR区域，我们获得了亲和力较低但能够同时识别PD-L1和CTLA-4的双功能纳米抗体。基于此发现，我们计划鉴定出这两个抗体结合抗原的热点氨基酸，进一步利用噬菌体展示技术优化改造非热点氨基酸，建立通用的双功能纳米抗体筛选改造平台；通过结构分析及CDR片段嫁接改造，制备PD-L1/CTLA4及其它免疫检查点受体的双功能纳米抗体，并验证其体内外活性，为后续相关免疫治疗药物的研制奠定基础。

Antibody-mediated tumor immunotherapy has achieved significant clinical results, and the world's first Nanobody KN035 targeting PD-L1 and KN044 targeting CTLA-4 have also entered clinical trials. Our previous research on the crystal structure of the KN035 / PD-L1 and KN044 / CTLA-4 complexes revealed that KN035 mainly binds PD-L1 through the longer CDR3 fragments on the surface of the nanobody, while KN044 recognizes CTLA-4 mainly through the CDR1 and CDR2 fragments. By simply grafting the CDR regions, we obtained bifunctional Nanobodies with lower affinity but are able to recognize both PD-L1 and CTLA-4. Based on this finding, we plan to identify the hot amino acids of these two antibodies that bind to the antigen. We will use phage display technology to optimize and transform non-hot amino acids and establish a universal bifunctional nanobody antibody screening and transformation platform. We will prepare high-affinity bifunctional Nanobodies of PD-L1 / CTLA-4 and other immune checkpoint receptors, and verify their activities in vivo and in vitro, laying a foundation for the subsequent development of related immunotherapy drugs.