Design and validation of a novel GPCR antibody screening method based on tripartite fluorescence complementation...

G protein-coupled receptors (GPCRs) are important drug targets involved in various physiological and pathological processes. GPCR-targeting antibody drugs offer notable advantages in terms of specificity, half-life, and reduced toxic side effects, thereby attracting increasing attention. However, the development of GPCR antibodies faces significant challenges, primarily due to the difficulty in obtaining stable antigens and the existence of interspecies homology. In this study, we developed a novel antibody screening approach that combines fluorescence complementation technology with antibody phage display technology. We use cells expressing GPCR on their surface as antigens, preserving the receptors in their native conformation. The phage display library enables in vitro screening, thereby circumventing the interspecies homology issues associated with in vivo immunization. The feasibility of this method was validated using the marketed GPCR antibody drug Mogamulizumab as a model system. The utilization of a tripartite split EGFP (enhanced green fluorescent protein) ensured high detection specificity. Collectively, the establishment of this method provides a new technical approach and conceptual framework for the screening of GPCR-targeting antibody drugs.