The inhibitory receptor NKG2A-CD94 is mainly expressed on NK cells and some T cell and mediates an inhibitory signal through association with a non-classical MHC class I molecule HLA-E, which is commonly over-expressed in human cancers. Targeting NKG2A with monoclonal antibody holds potentials in immunotherapy of cancer. However, proteins with homologous sequences such as NKG2C/CD94 or NKG2E/CD94 complexes generally deliver an activating signal upon ligand binding. NKG2A-specific antagonizing antibodies would be needed to further explore therapeutic potentials of targeting NKG2A for immunotherapy of cancer. We have developed and characterized panels of monoclonal antibodies (mAbs) that specifically recognize NKG2A. Balb/c and SJL mice had been immunized with recombinant NKG2A/CD94 protein, recombinant plasmids encoding hNKG2A or stable cell line with ectopic expression of hNKG2A. Splenocytes from such immunized animals were collected for construction of phage-displayed antibody library in a single chain variable fragment (scFv) format. The NKG2A-specific antibodies, that had no detectable binding to NKG2C, NKG2E or CD94, were isolated through multiple rounds of phage panning and ELISA-based screening. Such antibodies also block HLA-E ligand binding and enhanced cytotoxicity of NK cell lines and primary NK cells on cancer cells. The final lead is a humanized antibody which behaves well in stability test. Lab scale processes are successfully developed and confirmed. The safety and efficacy will be further validated.

Citation Format: Teddy Yang, Jing Gao, Jingyun Yao, Dongxu Wang, Ken Dai. Discovery of Anti-NKG2A antibody from immunized phage display approach [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5653.