Potent and Selective Mitogen-Activated Protein Kinase Kinase 1/2 (MEK1/2) Heterobifunctional Small-molecule Degraders.

Previously, we reported a first-in-class von Hippel-Lindau (VHL)-recruiting mitogen-activated protein kinase kinases 1 and 2 (MEK1/2) degrader, MS432. To date, only two MEK1/2 degrader papers have been published and very limited structure-activity relationships (SAR) have been reported. Here, we describe our extensive SAR studies exploring both von Hippel-Lindau (VHL) and cereblon (CRBN) E3 ligase ligands and a variety of linkers, which resulted in two novel, improved VHL-recruiting MEK1/2 degraders, (MS928) and (MS934), and the first CRBN-recruiting MEK1/2 degrader (MS910).

Discovery of a First-in-Class Mitogen-Activated Protein Kinase Kinase 1/2 Degrader.

MEK1 and MEK2 (also known as MAP2K1 and MAP2K2) are the "gatekeepers" of the ERK signaling output with redundant roles in controlling ERK activity. Numerous inhibitors targeting MEK1/2 have been developed including three FDA-approved drugs. However, acquired resistance to MEK1/2 inhibitors has been observed in patients, and new therapeutic strategies are needed to overcome the resistance.