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.