A Bioluminescence Resonance Energy Transfer-Based Approach for Determining Antibody-Receptor Occupancy In Vivo

Yu Tang; Kshitij Parag-Sharma; Antonio L Amelio; Yanguang Cao

doi:10.1016/j.isci.2019.05.003

A Bioluminescence Resonance Energy Transfer-Based Approach for Determining Antibody-Receptor Occupancy In Vivo

iScience. 2019 May 31:15:439-451. doi: 10.1016/j.isci.2019.05.003. Epub 2019 May 8.

Authors

Yu Tang¹, Kshitij Parag-Sharma², Antonio L Amelio³, Yanguang Cao⁴

Affiliations

¹ Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, 2318 Kerr Hall, Chapel Hill, NC 27599-7569, USA.
² Graduate Curriculum in Cell Biology & Physiology, Biological & Biomedical Sciences Program, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
³ Biomedical Research Imaging Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
⁴ Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, 2318 Kerr Hall, Chapel Hill, NC 27599-7569, USA; Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: yanguang@unc.edu.

Abstract

Elucidating receptor occupancy (RO) of monoclonal antibodies (mAbs) is a crucial step in characterizing the therapeutic efficacy of mAbs. However, the in vivo assessment of RO, particularly within peripheral tissues, is greatly limited by current technologies. In the present study, we developed a bioluminescence resonance energy transfer (BRET)-based system that leverages the large signal:noise ratio and stringent energy donor-acceptor distance dependency to measure antibody RO in a highly selective and temporal fashion. This versatile and minimally invasive system enables longitudinal monitoring of the in vivo antibody-receptor engagement over several days. As a proof of principle, we quantified cetuximab-epidermal growth factor receptor binding kinetics using this system and assessed cetuximab RO in a tumor xenograft model. Incomplete ROs were observed, even at a supratherapeutic dose of 50 mg/kg, indicating that fractional target accessibility is achieved. The BRET-based imaging approach enables quantification of antibody in vivo RO and provides critical information required to optimize therapeutic mAb efficacy.

Keywords: Biological Sciences; Cell Biology; Optical Imaging.

Abstract

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