A Novel Gain-of-Signal Assay to Detect Targeted Protein Degradation.

Targeted protein degradation offers a promising avenue for expanding therapeutic development to previously inaccessible proteins of interest by regulating the target abundance rather than activity. However, current methods to screen for effective degraders serve as major bottlenecks for the development of degrader therapies. Here, we develop a novel assay platform for identification and characterization of macromolecules capable of inducing targeted degradation of oncogenic phosphatase SHP2. Unlike traditional reporter assays that utilize loss-of-signal readouts to detect degradation, our assay platform expresses a robust fluorescence signal in response to the depletion of a target protein and incorporates additional measures intended to prevent undesirable false positives. Using this gain-of-signal assay, we successfully identified novel macromolecule SHP2 degraders from a screen of 192 candidates and proposed design principles for further development of macromolecule degraders. This work demonstrates a proof of concept for gain-of-signal assays as a tool for screening targeted degrader candidates.