Discovery and characterization of a VHL molecular glue degrader for cysteine dioxygenase 1

The Von Hippel-Lindau tumor suppressor (VHL) is one of the most widely exploited E3 ligases for inducing targeted protein degradation. Over the past several years, VHL chemical probes have been conjugated to various ligands to generate Proteolysis Targeting Chimeras, or PROTACs, which are hetero-bifunctional molecules that bind both VHL and the intended target independently to form a ternary complex leading to selective targeted protein degradation. However, to date no bona fide molecular glue degraders for VHL have been reported. Molecular glues overcome several shortcomings of PROTACs due to their conventional drug-like small molecule character.

We describe the discovery of a bona fide VHL molecular glue degrader for CDO1 by screening protein arrays with VHL chemical matter. We demonstrate using biochemical, biophysical and cellular assays that this molecular glue degrader facilitates the assembly of a VHL-Compound-CDO1 ternary complex and brings about VHL-dependent degradation of exogenously expressed CDO1 in engineered 786-0 cells, and endogenous CDO1 in HUH7 liver cells. Applying SAR, we developed an improved molecular glue molecule which results in higher ternary complex affinity. The x-ray structure of the ternary complex reveals key interactions that drive the recruitment of CDO1 to the novel protein interaction surface created on VHL by the glue degrader molecule.