Associate Principal Scientist AstraZeneca CAMBRIDGE, England, United Kingdom
Abstract: The landscape of drug discovery is rapidly changing, as many validated drug targets are becoming exceedingly difficult to address with traditional small molecules inhibitors. In this context, PROteolysis Targeting Chimeras (PROTACs) and molecular glue degraders are emerging as promising novel therapeutic modalities to expand the scope of the “druggable” proteome. They function by inducing or stabilizing an interaction between an E3 ligase and the target protein, leading to the ubiquitination and proteasomal degradation of the protein of interest. To develop such compounds, one key parameter to optimize is their ability to form a stable ternary complex both with the target protein and the E3 ligase. We have recently expanded our portfolio of techniques to characterize these complexes in vitro by acquiring a novel technology termed Flow Induced Dispersion Analysis (FIDA). FIDA uses Taylor dispersion analysis to measure the hydrodynamic radius of fluorescently-labelled molecules in solution. We will present how we established a FIDA assay to characterize a protein – E3 ligase interaction and to support the identification and optimization of molecular glue compounds against an “undruggable” target. FIDA was used as a biophysical orthogonal method to validate findings from a Fluorescence Resonance Energy Transfer (FRET) assay and showed that the affinity of a protein – E3 ligase interaction could be enhanced by small molecules, thereby providing evidence that a molecular glue mechanism could be a promising strategy to address this challenging target. Furthermore, the FIDA assay was instrumental to distinguish true hits from false positives following a FRET pilot screen. This work exemplified how FIDA can complement standard biochemical and biophysical methods in drug discovery projects, particularly against intractable targets.
