Abstract LB210: RenNano® mice: A heavy-chain-only antibody platform for the generation of nanobody therapeutics

Abstract

Abstract Monoclonal antibodies have been used to successfully treat various diseases, including tumors, autoimmune diseases, and infectious diseases. Traditional antibodies are comprised of a tetramer of two heavy chains and two light chains, totaling 150 kDa in molecular weight. However, the large size of antibodies can limit the therapeutic application; in particular, the penetration of tumors and the blood brain barrier (BBB) is not always feasible. In contrast to traditional antibodies, heavy-chain-only antibodies (HCAbs) are significantly smaller (~75 kDa), as they contain only two heavy chains. Since the heavy chain variable domain of HCAbs (i.e., VHH or single domain antibody, sdAb, or nanobody) is solely responsible for antigen recognition, nanobodies can function independently as a therapeutic molecule, which may be advantageous for penetrating tumors or the BBB. Previously, we generated a fully human antibody mouse platform, RenMabTM, in which the murine heavy chain and kappa light chain variable domains were replaced by the full human heavy chain and kappa light chain V(D)J loci in situ. Here, we have further modified the RenMabTM model to generate a fully human heavy-chain-only antibody mouse model, termed RenNano®. The modified heavy chain constant regions of RenNano® mice allow them to spontaneously produce HCAbs. Flow cytometry and biolayer interferometry confirmed that RenNano®-derived HCAbs can bind antigens without light chains. Despite this reliance on the heavy chain only variable regions for antigen specificity, RenNano® mice can generate antigen-specific antibodies with high affinity (10−8 -10−9 KD) upon immunization with various antigens. In addition, many RenNano®-derived HCAbs exhibited a longer CDR3 length, which could promote the recognition of difficult-to-reach epitopes. Furthermore, RenNano®-derived HCAbs have favorable diversity, and excellent developability properties such as a higher degree of hydrophilicity. Anti-4-1BB HCAbs can also activate 4-1BB-NF-κB signaling in a dose-dependent manner, as demonstrated in reporter assays. In summary, the full human heavy-chain-only antibody mice, RenNano®, can produce human HCAb with high affinity and good efficacy. Thus, RenNano® is a powerful platform to discover HCAb/nanobodies for various therapeutic applications. Citation Format: Yiqing Hu, Qi Zhang, Lijun Zhang, Yabo Zhang, Huizhen Zhao, Jiawei Yao, Liu Yang, Baihong Liu, Shensen Wang, Zhengfang Su, Li Hui, Qingcong Lin, Qiangqiang Ma, Yuelei Shen. RenNano® mice: A heavy-chain-only antibody platform for the generation of nanobody therapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB210.