Development of Potent and Selective CK1α Molecular Glue Degraders.

Molecular glue degraders (MGDs) are small molecules that facilitate proximity between a target protein and an E3 ubiquitin ligase, thereby inducing target protein degradation. Glutarimide-containing compounds are MGDs that bind cereblon (CRBN) and recruit neosubstrates. Through explorative synthesis of a glutarimide-based library, we discovered a series of molecules that induce casein kinase 1 alpha (CK1α) degradation. By scaffold hopping and rational modification of the chemical scaffold, we identified an imidazo[1,2-a]pyrimidine compound that induces potent and selective CK1α degradation. A structure-activity relationship study of the lead compound, QXG-6442, identified the chemical features that contribute to degradation potency and selectivity compared to other frequently observed neosubstrates. The glutarimide library screening and structure-activity relationship medicinal chemistry approach we employed is generally useful for developing new molecular glue degraders toward new targets of interest.