EEDi-5285: An Exceptionally Potent, Efficacious, and Orally Active Small-Molecule Inhibitor of Embryonic Ectoderm Development

Inhibition of embryonic ectoderm development (EED) is a new cancer therapeutic strategy. Herein, we report our discovery of EEDi-5285 as an exceptionally potent, efficacious, and orally active EED inhibitor. EEDi-5285 binds to the EED protein with an IC₅₀ value of 0.2 nM and inhibits cell growth with IC₅₀ values of 20 pM and 0.5 nM in the Pfeiffer and KARPAS422 lymphoma cell lines, respectively, carrying an EZH2 mutation. EEDi-5285 is approximately 100 times more potent than EED226 in binding to EED and >300 times more potent than EED226 in inhibition of cell growth in the KARPAS422 cell line. EEDi-5285 has excellent pharmacokinetics and achieves complete and durable tumor regression in the KARPAS422 xenograft model in mice with oral administration. The cocrystal structure of EEDi-5285 in a complex with EED defines the precise structural basis for their high binding affinity. EEDi-5285 is the most potent and efficacious EED inhibitor reported to date.