Evaluation of Cereblon-Directing Warheads for the Development of Orally Bioavailable PROTACs.

PROTACs usually occupy physicochemical space outside the one defined by classical drug-like molecules, which often presents considerable challenges in their optimization and development for oral administration. We have previously reported phenyl glutarimide (PG)-based BET PROTAC SJ995973, with improved overall degradation and antiproliferative activities compared to its direct thalidomide-based analogue dBET1, but similarly poor pharmacokinetic profile. To further demonstrate the PG utility, we describe here optimization efforts that led to the discovery of an orally bioavailable BET-PROTAC SJ44236 (), and results of a comprehensive comparative study with analogues containing alternative CRBN-directing warheads.

Leveraging Dual-Ligase Recruitment to Enhance Protein Degradation via a Heterotrivalent Proteolysis Targeting Chimera.

Proteolysis targeting chimera (PROTAC) degraders are typically bifunctional with one E3 ligase ligand connected to one target protein ligand via a linker. While augmented valency has been shown with trivalent PROTACs targeting two binding sites within a given target protein, or used to recruit two different targets, the possibility of recruiting two different E3 ligases within the same compound has not been demonstrated. Here we present dual-ligase recruitment as a strategy to enhance targeted protein degradation.

Structure-Activity Relationship of Potent, Selective, and Orally Bioavailable Molecular Glue Degraders of CK1α.

The original molecular glue degraders (thalidomide, lenalidomide, and pomalidomide) are known to bind to cereblon (CRBN) and alter its surface to induce recruitment, ubiquitination, and degradation of therapeutically valuable neosubstrates (IKZF1, IKZF3, and CK1α). With the aim of understanding and modulating neosubstrate specificity, we recently reported the discovery of SJ3149 (), a selective and potent molecular glue degrader of CK1α, that is active in multiple cancer cell lines. Herein, we describe the medicinal chemistry efforts that resulted in the discovery of SJ3149 as well as other potent and selective CK1α degraders.

Addressing common challenges of biotherapeutic protein peptide mapping using recombinant trypsin.

Peptide mapping is the key method for characterization of primary structure of biotherapeutic proteins. This method relies on digestion of proteins into peptides that are then analyzed for amino acid sequence and post-translational modifications. Owing to its high activity and cleavage specificity, trypsin is the protease of choice for peptide mapping.

Selective CK1α degraders exert antiproliferative activity against a broad range of human cancer cell lines.

Molecular-glue degraders are small molecules that induce a specific interaction between an E3 ligase and a target protein, resulting in the target proteolysis. The discovery of molecular glue degraders currently relies mostly on screening approaches. Here, we describe screening of a library of cereblon (CRBN) ligands against a panel of patient-derived cancer cell lines, leading to the discovery of SJ7095, a potent degrader of CK1α, IKZF1 and IKZF3 proteins.