Treatment Of MLL-rearranged Leukemia Research Articles

Uncovering NOTCH1 as a Promising Target in the Treatment of MLL-Rearranged Leukemia.

MLL rearrangement (MLLr) is responsible for the development of acute leukemias with poor outcomes. Therefore, new therapeutic approaches are urgently needed. The NOTCH1 pathway plays a critical role in the pathogenesis of many cancers including acute leukemia. Using a CRISPR/Cas9 MLL-AF4/-AF9 translocation model, the newly developed NOTCH1 inhibitor CAD204520 with less toxic side effects allowed us to unravel the impact of NOTCH1 as a pathogenic driver and potential therapeutic target in MLLr leukemia. RNA sequencing (RNA-seq) and RT-qPCR of our MLLr model and MLLr cell lines showed the NOTCH1 pathway was overexpressed and activated. Strikingly, we confirmed this elevated expression level in leukemia patients. We also demonstrated that CAD204520 treatment of MLLr cells significantly reduces NOTCH1 and its target genes as well as NOTCH1 receptor expression. This was not observed with a comparable cytarabine treatment, indicating the specificity of the small molecule. Accordingly, treatment with CAD204520 resulted in dose-dependent reduced proliferation and viability, increased apoptosis, and the induction of cell cycle arrest via the downregulation of MLL and NOTCH1 target genes. In conclusion, our findings uncover the oncogenic relevance of the NOTCH1 pathway in MLLr leukemia. Its inhibition leads to specific anti-leukemic effects and paves the way for further evaluation in clinical settings.

Abstract 3943: Discovery of a novel menin-MLL inhibitor for potential treatment of MLLr leukemias and NPM1c AML

Abstract Rearrangement of the mixed lineage leukemia (MLL) gene occurs in up to 10% of acute leukemias and is particularly prevalent in infant acute leukemias (~80% of infant ALL cases). MLL-rearranged (MLLr) leukemia is one of the high-risk types of leukemia with aggressive nature, resistance to therapy, and high frequency of early relapse, and currently there are no targeted therapies for its treatment. So, there is huge unmet medical needs for MLLr leukemias. The protein protein interaction (PPI) between menin and MLLr is critical to the pathogenesis of MLLr-driven leukemias by deregulation of the HOXA and MEIS1 genes. It has been demonstrated by both preclinical and clinical studies that blockage of this PPI with menin inhibitors has potential therapeutic effects on MLLr associated acute leukemias. NPM1 mutation (NMP1c) is a frequently mutated gene found in AML, and NMP1 mutated AML depends on menin-MLL interaction for leukemogenesis. Given the fact that wild type MLL and MLLr have similar leukemogenesis-driven target genes like HOXA and MEIS1, as well as the same binding pocket on menin, it was therefore conceived that menin inhibitor could be useful to the treatment of NPM-mutated AML, which was again supported by both preclinical and clinical data. Herein, we would like to report the discovery of our proprietary menin inhibitor. Taking advantage of a couple of key interactions with menin protein, our compounds has relatively low molecular weight for a challenging PPI target, however, demonstrated comparable to or even better potency than those menin inhibitors in clinical trials. Besides in vitro pharmacology data, the DMPK, PK/PD and in vivo efficacy in animal model will be discussed too. Citation Format: Taishan Hu, Zhilin Deng, Honghai Li, Xiaochu Ma, Quanrong Shen, Lei Zhang, Peihua Sun, Ye Hua, Byran Huang. Discovery of a novel menin-MLL inhibitor for potential treatment of MLLr leukemias and NPM1c AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3943.

Affinity switching of the LEDGF/p75 IBD interactome is governed by kinase-dependent phosphorylation

Lens epithelium-derived growth factor/p75 (LEDGF/p75, or PSIP1) is a transcriptional coactivator that tethers other proteins to gene bodies. The chromatin tethering function of LEDGF/p75 is hijacked by HIV integrase to ensure viral integration at sites of active transcription. LEDGF/p75 is also important for the development of mixed-lineage leukemia (MLL), where it tethers the MLL1 fusion complex at aberrant MLL targets, inducing malignant transformation. However, little is known about how the LEDGF/p75 protein interaction network is regulated. Here, we obtained solution structures of the complete interfaces between the LEDGF/p75 integrase binding domain (IBD) and its cellular binding partners and validated another binding partner, Mediator subunit 1 (MED1). We reveal that structurally conserved IBD-binding motifs (IBMs) on known LEDGF/p75 binding partners can be regulated by phosphorylation, permitting switching between low- and high-affinity states. Finally, we show that elimination of IBM phosphorylation sites on MLL1 disrupts the oncogenic potential of primary MLL1-rearranged leukemic cells. Our results demonstrate that kinase-dependent phosphorylation of MLL1 represents a previously unknown oncogenic dependency that may be harnessed in the treatment of MLL-rearranged leukemia.

Abstract 5077: A novel small molecule menin-MLL inhibitor for potential treatment of MLL-rearranged leukemias

Abstract Patients with MLL-rearranged leukemia typically have a poor prognosis. With chemotherapy and stem cell transplantation as current standard of care, the 5-year survival rate is estimated to be only about 35%. As the leukemogenic activity of MLL fusion proteins has been shown to be dependent on their direct interaction with menin, development of small molecules that block the menin-MLL interaction is a promising therapeutic strategy for the treatment of this disease. Although small molecule menin-MLL inhibitors have been reported, previously published compounds exhibited modest cellular potency and/or poor pharmacokinetic properties. We now describe a novel, potent, and selective small molecule menin-MLL inhibitor that effectively treats MLL leukemias in in vivo models and demonstrate its potential clinical utility. The compound selectively inhibits the growth of a panel of MLL-rearranged cell lines relative to non MLL-rearranged cell lines, displays favorable pharmacokinetic properties, and induces tumor regression in an MV4;11 subcutaneous xenograft mouse model, with durable tumor suppression even after dosing is discontinued. In both the MV4;11 and MOLM13 disseminated leukemia models, the compound confers a prolonged survival benefit compared to an untreated group when dosed orally once daily at doses that are well-tolerated in the animals. We have used this potent and selective menin inhibitor to investigate the functional cellular response of MLL-rearranged cell lines to menin inhibition, assessing cell growth, cell cycle and gene expression responses over time, and compared that response to other epigenetic inhibitors and demonstrate significantly increased apoptosis which correlates with tumor regression measured both in early and long term readouts in xenograft and systemic leukemia models. We describe a menin-MLL inhibitor with optimized drug-like properties that demonstrates potential clinical utility in preclinical models of MLL leukemias. The compound is currently under further preclinical evaluation. Citation Format: Tao Wu, Linda Kessler, Shuangwei Li, Trupta Purohit, Shisheng Li, Hongzhi Miao, Brian Linhares, Rasmus Hansen, Jeff Kucharski, Yi Wang, Ke Yu, Katarzyna Kempinska, Tess Ely, Szymon Klossowski, Ata Zarieh, Ulf Peters, Jun Feng, Yvonne Yao, Yuan Liu, Bo Wen, Francis Burrows, Duxin Sun, Jingchuan Zhang, Levan Darjania, Dana Hu-Lowe, Patrick Zarrinkar, Liansheng Li, Tomasz Cierpicki, Jolanta Grembecka, Pingda Ren, Yi Liu. A novel small molecule menin-MLL inhibitor for potential treatment of MLL-rearranged leukemias [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5077. doi:10.1158/1538-7445.AM2017-5077

Preclinical Characterization of a Potent, Selective Inhibitor of the Protein Methyltransferase DOT1L for Use in the Treatment of MLL-Rearranged Leukemia.

AbstractAbstract 2379The enzymatic activity of the protein methyltransferase (PMT) DOT1L has been shown to be a driver of cell proliferation in MLL-rearranged leukemia. Our group has previously reported the design of potent and selective aminonucleoside inhibitors of DOT1L [Daigle et al. (2011) Cancer Cell 20: 53–65; Basavapathruni et al. (2012) Chem. Biol. Drug Design, in press]. Structure-guided design, together with robust biochemical and biological assays, was used to optimize the potency, selectivity and pharmacological features of the aminonucleosides, resulting in the compound EPZ-5676. EPZ-5676 is an S-adenosyl methionine (SAM) competitive inhibitor of DOT11L that displays a Ki value of 80 pM and a drug-target residence time of > 24 hours. The compound is highly selective for DOT1L, demonstrating > 37,000-fold selectivity against all other PMTs tested. Crystallographic studies reveal that the high affinity, durable inhibition of DOT1L by EPZ-5676 has its origin in a conformational adaptation of the protein that attends inhibitor binding, extending the compound binding pocket to include novel recognition elements beyond the SAM binding active site. Treatment of leukemia cells with EPZ-5676 results in concentration- and time-dependent reduction of H3K79 methylation without effect on the methylation status of other histone sites. The reduction of H3K79 methylation leads to inhibition of key MLL target genes and selective, apoptotic cell killing in MLL-rearranged leukemia cells, but has minimal impact on non-rearranged cells. EPZ-5676 is highly soluble in aqueous solution and can thus be formulated for intravenous administration. The effective pharmacokinetic half-life of EPZ-5676 in systemic circulation has been measured to be 0.25 and 1.5 h in rats and dogs, respectively. A nude rat subcutaneous xenograft model of MLL-rearranged leukemia has been established. Continuous intravenous infusion of EPZ-5676 for 21 days in this model leads to dose-dependent anti-tumor activity. At the highest dose, complete tumor regressions are achieved with no regrowth for up to 32 days after the cessation of treatment (Figure 1). [Display omitted] Disclosures:Pollock:Epizyme: Employment, Equity Ownership. Daigle:Epizyme: Employment, Equity Ownership. Therkelsen:Epizyme: Employment, Equity Ownership. Basavapathruni:Epizyme: Employment, Equity Ownership. Jin:Epizyme: Employment, Equity Ownership. Allain:Epizyme: Employment, Equity Ownership. Klaus:Epizyme, Inc.: Employment, Equity Ownership. Raimondi:Epizyme: Employment, Equity Ownership. Porter Scott:Epizyme: Employment, Equity Ownership. Chesworth:Epizyme: Employment, Equity Ownership. Moyer:Epizyme: Employment, Equity Ownership. Copeland:Epizyme Inc.: Employment, Equity Ownership. Richon:Epizyme, Inc.: Employment, Equity Ownership. Olhava:Epizyme: Employment.