Alternative Binding Scaffolds: Multipurpose Binders for Applications in Basic Research and Therapy

Abstract

What You Will Learn in This ChapterNext to monoclonal antibodies (mAbs), alternative binding scaffolds have proven to be powerful tool reagents and therapeutic entities over the past decades. In contrast to their hetero-tetrameric, macromolecular counterparts, these affinity reagents are based on non-antibody structures and provide several advantages, like a smaller size, improved biophysical properties as well as the possibility to engage difficult-to-address target proteins through surface-exposed binding sites. With three alternative binding scaffolds being approved by the US Food and Drug Administration (FDA) to date and many more currently investigated in clinical trials, scaffold proteins are on a rise to become promising next-generation therapeutics. Additionally, these binders have successfully been employed (pre)clinically in a variety of applications, e.g., as imaging reagents for the detection and monitoring of various cancers, given that their small format enables an efficient distribution in cancerous tissue while at the same time ensuring a rapid elimination from the system by the kidney. In addition, alternative scaffolds are often more robust than mAbs and have also proven to be versatile and efficient affinity reagents for applications in basic research, such as affinity purifications and structural biology. Advances in high-throughput screening using different display technologies and protein engineering have facilitated the generation of novel binding scaffolds with high affinities and specificities and have paved the way for the expansion of the alternative binding scaffold toolbox.