Catalytic site remodelling of the DOT1L methyltransferase by selective inhibitors

Abstract

Selective inhibition of protein methyltransferases is a promising new approach to drug discovery. An attractive strategy towards this goal is the development of compounds that selectively inhibit binding of the cofactor, S-adenosylmethionine, within specific protein methyltransferases. Here we report the three-dimensional structure of the protein methyltransferase DOT1L bound to EPZ004777, the first S-adenosylmethionine-competitive inhibitor of a protein methyltransferase with in vivo efficacy. This structure and those of four new analogues reveal remodelling of the catalytic site. EPZ004777 and a brominated analogue, SGC0946, inhibit DOT1L in vitro and selectively kill mixed lineage leukaemia cells, in which DOT1L is aberrantly localized via interaction with an oncogenic MLL fusion protein. These data provide important new insight into mechanisms of cell-active S-adenosylmethioninecompetitive protein methyltransferase inhibitors, and establish a foundation for the further development of drug-like inhibitors of DOT1L for cancer therapy.

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].…”

Mixed-Lineage Leukemia Fusions and Chromatin in Leukemia

“…Of importance, no side effects of the inhibitor, EPZ-5676, have been reported despite initial concerns of potential transcriptional suppression of the 2 -5 Â 10 3 genes that are normally marked by H3K79me2 (Stein and Tallman 2016). The initial successful development of DOT1L inhibitors was followed by small molecule discovery by other groups and there are currently multiple DOT1L inhibitors with varying pharmacokinetic properties available for research (Yu et al 2012;Yi et al 2015;Chen et al 2016;Dafflon et al 2016;Spurr et al 2016). Although these initial results are encouraging, there is no doubt these approaches will need to be combined with other therapies to realize the maximal therapeutic benefit.…”

Epigenetic regulators and their impact on therapy in acute myeloid leukemia

“…Several DOT1L inhibitors have been successfully tested in MLL-rearranged AML (MLL-AF6 and MLL-AF9) cells in xenograft models, where they have impeded proliferation and caused cell cycle arrest in cells expressing the MLL fusion. [149][150][151][152][153] The DOT1L inhibitor Pinometostat (EPZ-5676) was able to cause sustained complete remission in a xenograft model. The first results from its phase I clinical trial for, thus far, 49 patients with advanced hematological malignancies, including relapsed/refractory MLL-rearranged AML (NCT01684150), revealed an overall response in 6 patients (2 of whom achieved a CR) with an acceptable safety profile.…”