composition of antibody versus protein scaffold

Compared with the other protein based affinity tools (for example, monoclonal antibodies and their fragments), Affibody molecules have very small size and hence have favorable properties for diagnostic imaging. There are several metabolic markers that have been developed (the most used one is fluorodeoxyglucose-positron emission tomography (FDG-PET) 13), but a scarcity of tumor receptor-specific tracers. Imaging is an important tool to identify, characterize and monitor tumors. The potential for translation to clinical use is being explored and can be categorized in engineered molecules for diagnostic imaging, use for improving therapeutic outcome by providing guidance during surgery, and therapeutically active molecules to be used as drugs. The Affibody molecule is very robust, and has generated useful biotech tools, for example, as the alkali-resistant active component in MabSelect SuRe for affinity purification of mAbs (MabSelect SuRe, Catalog number 17-5438-01, GE Healthcare, Chicago, IL, USA) or as part of a hot start PCR kit, where the Affibody molecule improves the fidelity of the DNA polymerase by binding to it at ambient temperature, and by surviving a large number of heat cycles (Phusion Hot Start II DNA Polymerase, Catalog number: F549L, Thermofisher Scientific, Waltham, MA, USA). 8 Affibody molecules can be selected to a large variety of different proteins, and can be functionalized with genetic fusions to protein modules 9, 10 or by chemical conjugation to toxic molecules, 11 reviewed in Löfblom et al. By randomizing amino acids on two of the three helices, large libraries can be constructed, from which potent binders can be isolated by a variety of display methods, 5, 6, 7 and the scaffold has been engineered for improved synthesis and solubility. 4 demonstrated that a small three-helical subdomain of a natural receptor for the Fc-portion of IgG could be utilized as a general scaffold for diversity. In this review, recent advances of the Affibody technology will be reviewed with an emphasis on translational research.

1, 2 A few of the scaffolds have reached early clinical development stage, 3 and the Affibody molecule class is among those. Advances in protein engineering technology in the late 90s and early 2000 allowed the generation of several non-antibody protein scaffold formats.

Composition of antibody versus protein scaffold