EPZ011989 equipotently inhibits mutant and wild-type EZH2 with an inhibition constant (Ki) of <3 nM. EPZ011989 is also a specific EZH2 inhibitor with a >15-fold selectivity over EZH1 and >3000-fold selectivity relative to the Ki of 20 other histone methyltransferases (HMTs) tested. As evidenced by the human and rat liver microsomal turnover, EPZ011989 also exhibits metabolic stability. EPZ011989 reduces cellular H3K27 methylation in the Y641F, mutant-bearing human lymphoma cell line, WSU-DLCL2, with an IC50 below 100 nM. EPZ011989 inhibits H3K27me3 in wild-type EZH2 AML cell lines (Kasumi-1, MOLM-13, and MV4-11) at a concentration of 0.625 μM after only four days of treatment. At these concentrations and this time point, no change in viability among these three cell lines is observed and only minimal proliferation inhibition in MV4-11 and MOLM-13 cells.
In vivo
EPZ011989 demonstrates significant tumor growth inhibition in a mouse xenograft model of human B cell lymphoma. EPZ011989 is able to elicit robust methyl mark inhibition and antitumor activity.
