EPZ011989 trifluoroacetate is a potent, selective orally bioavailable EZH2 inhibitor with Ki 3000-fold selectivity over other HMTase.IC50 value: 15-fold selectivity over EZH1 and >3000-fold selectivity relative to the Ki of 20 other histone methyltransferases (HMTs) tested. EPZ011989 also exhibits metabolic stability. Furthermore, EPZ011989 reduces cellular H3K27 methylation in the Y641F, mutant-bearing human lymphoma cell line, WSU-DLCL2, with an IC50 below 100 nM. This functional response translates to activity in a long-term proliferation assay where EPZ011989 demonstrates an average lowest cytotoxic concentration (LCC) in WSU-DLCL2 cells of 208 nM. In vivo: The LCC parameter, when corrected for plasma protein-binding, predicts an efficacious plasma level in mouse for EPZ011989 of 158 ng/mL. The pharmacokinetics in SCID mice following oral administration of 125, 250, 500, and 1000 mg/kg indicated that the 1000 mg/kg dose provided coverage over the LCC for 24 h, while the 250 and 500 mg/kg doses provided coverage over this value for approximately 8 h. EPZ011989 demonstrates significant tumor growth inhibition in a mouse xenograft model of human B cell lymphoma.

[1]. Campbell JE, et al. EPZ011989, A Potent, Orally-Available EZH2 Inhibitor with Robust in Vivo Activity. ACS Med Chem Lett. 2015 Mar 4;6(5):491-495.