Potent inhibition of DOT1L as treatment of MLL-fusion leukemia

Abstract

• EPZ-5676 is a potent DOT1Linhibitor that causes tumor regressions in a rat xenograft model of MLL-rearranged leukemia.Rearrangements of the MLL gene define a genetically distinct subset of acute leukemias with poor prognosis. Current treatment options are of limited effectiveness; thus, there is a pressing need for new therapies for this disease. Genetic and small molecule inhibitor studies have demonstrated that the histone methyltransferase DOT1L is required for the development and maintenance of MLL-rearranged leukemia in model systems. Here we describe the characterization of EPZ-5676, a potent and selective aminonucleoside inhibitor of DOT1L histone methyltransferase activity. The compound has an inhibition constant value of 80 pM, and demonstrates 37 000-fold selectivity over all other methyltransferases tested. In cellular studies, EPZ-5676 inhibited H3K79 methylation and MLL-fusion target gene expression and demonstrated potent cell killing that was selective for acute leukemia lines bearing MLL translocations. Continuous IV infusion of EPZ-5676 in a rat xenograft model of MLL-rearranged leukemia caused complete tumor regressions that were sustained well beyond the compound infusion period with no significant weight loss or signs of toxicity. EPZ-5676 is therefore a potential treatment of MLL-rearranged leukemia and is under clinical investigation. (Blood. 2013;122(6):1017-1025 Introduction Rearrangements in the MLL gene at position 11q23 occur in 5% to 10% of acute leukemias of lymphoid, myeloid, or mixed/ indeterminant lineage and are especially common in infant acute leukemias and in secondary acute myeloid leukemias arising in patients following treatment of other malignancies with topoisomerase II inhibitors. [1][2][3][4] Acute leukemias bearing MLL rearrangements are aggressive diseases. Current treatment options are limited to chemotherapy and allogeneic hematopoietic stem cell transplantation; however, these have significant side effects and outcomes remain poor. As a result, there is intense interest in developing novel therapeutic strategies for this disease. The MLL gene encodes a large multidomain protein (MLL) that regulates transcription of developmental genes including the HOX genes. 1 The amino terminal portion of the protein contains regions that target MLL to DNA directly, whereas the carboxyl terminal portion of the protein contains a Su(Var)3-9, Enhancer of zeste and Trithorax domain with methyltransferase activity specific for lysine 4 of histone H3 (H3K4).5-9 MLL rearrangements result in the loss of the carboxyterminal methyltransferase domain and an in-frame fusion of the amino-terminal region of MLL to 1 of more than 60 potential fusion partners. [1][2][3] The vast majority of translocations result in oncogenic fusion proteins in which the native methyltransferase domain is replaced by sequences derived from AF4, AF9, AF10, and ENL, which interact with DOT1L directly or indirectly in complexes that promote transcriptional elongation.10-18 DOT1L is a histone methyltransferase enz...

Up-regulation of Histone Methyltransferase, DOT1L, by Matrix Hyaluronan Promotes MicroRNA-10 Expression Leading to Tumor Cell Invasion and Chemoresistance in Cancer Stem Cells from Head and Neck Squamous Cell Carcinoma

“…For example, DOT1L-regulated H3K79 methylation promotes leukemia formation induced by MLL-AF9 translocations (21). Treatment of MLL-rearranged leukemia with EPZ00477 or EPZ-5676 (potent and selective aminonucleoside inhibitors of DOT1L histone methyltransferase activity) causes cell death in acute leukemia lines bearing MLL translocations (33,34). Down-regulation of H3K79 methyltransferase, DOT1L, using specific DOT1LsiRNA also reduced proliferation of lung cancer cells (22).…”

MLL1 and DOT1L cooperate with meningioma-1 to induce acute myeloid leukemia

“…We recently showed that the histone methyltransferase DOT1L is absolutely required in MLL-AF9 leukemia and that the mechanism involves a specific dependence of MLL fusion target gene expression on functional DOT1L (18). Based on these data, a small molecule inhibitor of DOT1L is currently in phase I/II clinical development for MLL-rearranged leukemia (19,20). DOT1L methylates histone 3 on lysine 79 (H3K79); it is the predominant H3K79 methyltransferase and responsible for monomethylation (me1), dimethylation (me2), and trimethylation (me3) of H3K79 (21).…”

DOT1L Inhibitor EPZ-5676 Displays Synergistic Antiproliferative Activity in Combination with Standard of Care Drugs and Hypomethylating Agents inMLL-Rearranged Leukemia Cells

“…It has therefore been speculated that DOT1L enzymatic activity represents an oncogenic driver of MLL-r leukemia, and that inhibition of the DOT1L enzyme would represent a cogent approach to therapeutic intervention for MLL-r patients. This hypothesis has gained significant support recently through the demonstration that genetic knockdown of DOT1L message or small-molecule inhibition of DOT1L catalysis led to robust antiproliferative effects in MLL-r leukemia cells, with minimal effect on non-MLL-r cells, both in vitro and in vivo (Bernt et al, 2011;Daigle et al, 2011Daigle et al, , 2013Nguyen et al, 2011;Basavapathruni et al, 2012;Yu et al, 2012;Chen et al, 2013;Deshpande et al, 2013). Daigle et al (2013) reported the discovery of an extremely potent and selective DOT1L inhibitor, EPZ-5676 [(2R,3R,4S,5R)-2-(6-amino-9H-purin-9-yl)-5-((((1r,3S)-3-(2-(5-(tert-butyl)-1H-benzo [d]imidazol-2-yl)ethyl)cyclobutyl)(isopropyl)amino)methyl) tetrahydrofuran-3,4-diol].…”