Targeting DOT1L for Degradation in MLL-rearranged Leukemia

项目摘要/摘要 尽管急性白血病患者的治愈率取得了显著进展，但染色体易位 涉及混合血统白血病基因(MLL1)导致高度侵袭性急性白血病相关 对于儿童和成人患者来说，临床结果很差。目前的治疗选择效果有限； 因此，迫切需要治疗这种疾病的新方法。遗传学研究已经证明， 组蛋白甲基转移酶DOT1L是MLL重排(MLL-r)形成和维持所必需的 模型系统中的白血病。同样，前一个供资周期的工作清楚地定义了DOT1L的作用 高效、特异性DOT1L抑制剂EPZ-5676对MLL-r白血病的抑制作用 对MLL重排有显著选择性的抗增殖和促凋亡作用 细胞。随着匹米托定在I期临床试验中的进展，反应和随后的复发意味着 对抑制剂的获得性耐药性的发展。在这个提案中，我们试图了解生物 DOT1L抑制剂抗性的基础和开发一类新型小分子DOT1L降解剂以 克服阻力。在具体目标1中，我们试图通过详细的研究了解抗性的机制。 DOT1L获得性抗性发生过程中染色质结构和基因表达的研究 抑制物疗法。我们还将研究DOT1L在MLL-r白血病中的非酶作用，并确定 在抵抗状态下获得的依赖项。在具体目标2中，我们将领导一门化学和化学生物学 宣传和开发用于鉴定和优化第一个小分子的分析平台 内源性DOT1L蛋白的降解者。在具体目标3中，我们将利用我们的细胞培养和患者来源 探索DOT1L降解对基因表达和肿瘤影响的MLL-r白血病异种移植模型 在推动DOT1L降解物的点击到领先优化的同时，可以促进临床研究。我们 还将测试关于DOT1L降解物与DOT1L降解物的组合药物作用的药理学假设 MLL-r白血病的预测性人体模型。我们期待这些目标将带来更有效、毒性更低的新产品 对被诊断患有这种毁灭性疾病的儿童和成人的治疗。

Project Summary/Abstract Despite marked progress in the rate of cure among patients with acute leukemia, chromosomal translocations involving the mixed lineage leukemia gene (MLL1) give rise to highly aggressive acute leukemias associated with poor clinical outcomes for pediatric and adult patients. Current treatment options are of limited effectiveness; thus, there is a pressing need for new therapies for this disease. Genetic studies have demonstrated that the histone methyltransferase DOT1L is required for the development and maintenance of MLL-rearranged (MLL-r) leukemia in model systems. Likewise, work from the previous funding cycle clearly defined a role for DOT1L inhibition in MLL-r leukemia through characterization of a potent, specific DOT1L inhibitor, EPZ-5676 (pinometostat), that has remarkably selective anti-proliferative and pro-apoptotic effects on MLL-rearranged cells. As pinometostat has progressed through Phase I clinical trials, responses and subsequent relapses imply the development of acquired resistance to the inhibitor. In this proposal, we seek to understand the biological underpinnings of DOT1L inhibitor resistance and develop a novel class of small molecule DOT1L degraders to overcome resistance. In Specific Aim 1, we seek to understand the mechanisms of resistance through detailed studies of chromatin structure and gene expression following the development of acquired resistance to DOT1L inhibitor therapy. We will also investigate the non-enzymatic role of DOT1L in MLL-r leukemia and define dependencies acquired in the resistant state. In Specific Aim 2, we will lead a chemistry and chemical biology campaign and develop an assay platform for the identification and optimization of the first small molecule degraders of endogenous DOT1L protein. In Specific Aim 3, we will utilize our cell culture and patient-derived xenograft models of MLL-r leukemia to explore the impact of DOT1L degradation on gene expression and tumor progression while driving hit-to-lead optimization of DOT1L degraders that can prompt clinical investigation. We will also test pharmacological hypotheses regarding combinatorial drug action with DOT1L degraders in predictive human models of MLL-r leukemia. We expect these aims to bring new more efficacious, less toxic therapies to children and adults diagnosed with this devastating disease.