Selective Killing of Mixed Lineage Leukemia Cells by a Potent Small-Molecule DOT1L Inhibitor

Abstract

SUMMARY Mislocated enzymatic activity of DOT1L has been proposed as a driver of leukemogenesis in mixed lineage leukemia (MLL). The characterization of EPZ004777, a potent, selective inhibitor of DOT1L is reported. Treatment of MLL cells with the compound selectively inhibits H3K79 methylation and blocks expression of leukemogenic genes. Exposure of leukemic cells to EPZ004777 results in selective killing of those cells bearing the MLL gene translocation, with little effect on non-MLL-translocated cells. Finally, in vivo administration of EPZ004777 leads to extension of survival in a mouse MLL xenograft model. These results provide compelling support for DOT1L inhibition as a basis for targeted therapeutics against MLL.

Catalytic site remodelling of the DOT1L methyltransferase by selective inhibitors

“…Indeed, SGC0946 is a more potent DOT1L inhibitor than EPZ004777. Surface plasmon resonance (SPR) and a homogeneous biochemical assay with recombinant, purified DOT1L acting on a nucleosomal substrate yielded a K D of 0.25 ± 0.02 nM and IC 50 of 0.5 ± 0.1 nM for EPZ004777 (in agreement with previous work 17 ), while a K D of 0.06 nM and IC 50 0.3 ± 0.1 nM were measured for SGC0946 (Table 1; Fig. 3a,b).…”

“…EPZ004777 (Fig. 1c) is a near chemical derivative of SAM that inhibits DOT1L with extraordinary potency in a radionuclide homogeneous assay (IC 50 ¼ 400 pM), and possesses surprising selectivity for DOT1L compared with other SAM-dependent lysine and arginine methyltransferases 17 . Limited information is available regarding the design of EPZ004777, but most striking is the para-tert-butylphenyl appending group coupled via a urea linkage.…”

“…A subset of MLL fusion partners, including AF4, AF9 and AF10, aberrantly recruit DOT1L to select genomic loci leading to increased H3K79 methylation and transcriptional activation of genes essential for leukemogenesis 16 . Recently, the antileukemic activity of DOT1L inhibition by either genetic or pharmacological approaches resulted in selective killing of MLL-AF4/9/10 translocation carrying cells 10,17 . In particular, EPZ004777 (Fig.…”

“…In particular, EPZ004777 (Fig. 1c), a picomolar, specific, SAM-competitive inhibitor of DOT1L, selectively kills cells bearing MLL chromosomal rearrangements and extends survival in a murine xenograft model of MLL 17 . DOT1L inhibition by EPZ004777 also accelerated reprogramming of somatic cells into induced pluripotent stem cells 18 , suggesting that DOT1L inhibition may be useful in regenerative medicine.…”

Epigenetic cancer therapy: rationales, targets and drugs

“…For example, chromosomal translocations affecting the MLL gene cause mixed lineage leukemia that is characterized by highly defined gene expression changes associated with aberrant H3K79 methylation (Bernt et al, 2011). In agreement with this notion, a potent small-molecule inhibitor of the H3K79 methyltransferase DOT1L selectively killed cancer cells that harbored the MLL gene translocation (Daigle et al, 2011); thus providing a compelling paradigm for epigenetic therapy with a very high degree of cancer specificity.…”