Engineered antibody domains with significantly increased transcytosis and half-life in macaques mediated by FcRn

Abstract

Engineered antibody domains (eAds) are promising candidate therapeutics but their half-life is relatively short partly due to weak or absent binding to the neonatal Fc receptor (FcRn). We developed a novel approach to increase the eAd binding to FcRn based on a combination of structure-based design, computational modeling and phage display methodologies. By using this approach, we identified 2 IgG1 CH2-derived eAds fused to a short FcRn-binding motif derived from IgG1 CH3 that exhibited greatly enhanced FcRn binding with strict pH dependency. Importantly, the increased affinity resulted in significantly enhanced FcRn-mediated epithelial transcytosis and prolonged elimination half-life (mean 44.1 hours) in cynomolgus macaques. These results demonstrate for the first time that the half-life of isolated eAds can be prolonged (optimized) by increasing their binding to FcRn while maintaining their small size, which has important implications for development of therapeutics, including eAd-drug conjugates with enhanced penetration in solid tissues.

Keywords:

• antibody domains
• FcRn
• half-life
• transcytosis
• CH2
• CH3
• macaques

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgements

We thank Tina W. Ju of Stanford University for help.

Funding

This work was supported by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research, Federal funds from the NIH, National Cancer Institute, under Contract No. N01-CO-12400, and the Shanghai Pujiang Talent Program.

Author Contributions

TY and DSD designed research; TY, YW, YF, RG, LW, KC performed experiments; and TY and DSD analyzed the data and wrote the paper.