Discovery of molecular glue degraders via isogenic morphological profiling

Molecular glue degraders (MGDs) are small molecules that degrade proteins-of-interest via the ubiquitin-proteasome system. Historically, MGDs were discovered serendipitously. Current approaches for MGD discovery include cell-viability based drug screens or data mining of public transcriptomics and drug response datasets. The explored target space is consequently re-stricted to the essential proteins. Here we develop a high-throughput workflow for MGD discovery that also reaches the non-essential proteome. This workflow begins with the rapid synthesis of a compound library by Sulfur(VI) Fluoride Exchange chemistry coupled to a morphological profiling assay in isogenic cell lines that vary in levels of the E3 ligase CRBN. By com-paring the morphological changes induced by compound treatment across the isogenic cell lines, we were able to identify FL2-14 as a CRBN-dependent MGD targeting the non-essential protein GSPT2. We envision that this workflow would con-tribute to the discovery and characterization of MGDs targeting a wider range of proteins.