Designing durable apoptosis-targeting therapies for acute myeloid leukemia

 描述(由申请人提供)：尽管对新的和重新调整用途的小分子抑制剂继续感兴趣，但在过去的30年里，诊断为初发急性髓系白血病(AML)的成年患者的护理标准基本保持不变。最近的发展揭示了AML细胞对抗凋亡蛋白bcl2的依赖性，揭示了一种可以利用的分子依赖性。与此同时，一类被称为BH3模拟物的靶向治疗已经被开发出来，目的是抑制抗凋亡的bcl2家族蛋白。其中一种名为ABT-199的药物是bcl2的特异性抑制剂，目前正在进入治疗急性髓细胞白血病的第三阶段临床试验。鉴于到目前为止所有的靶向治疗都会产生耐药性，AML细胞能够获得对ABT-199的耐药性也就不足为奇了。最近，我们使用一种以通路为中心的功能获得筛查来提名MCL-1和BCL-XL作为AML对ABT-199耐药的主要驱动因素。此外，我们证明了在6个通过慢性药物暴露而产生的独立的ABT-199耐药AML细胞系中，其中一个或两个蛋白质都上调，并且与ABT-199共同靶向这些蛋白质可以延迟甚至阻止获得性耐药的发生。然而，目前，由于缺乏有效的口服生物可用化合物，我们直接靶向这些蛋白质的能力受到限制。在拟议的工作中，我们将使用药理学的、基于候选的方法和基于CRISPR/Cas9的无偏见的筛选来确定通过抑制bclxl和mcl1来增强AML中ABT-199活性的治疗靶点。这些检测的结果将通过一系列计算和体外方法进行鉴定，以确定那些具有最大翻译潜力的组合，这些领先组合随后将在急性髓细胞白血病的活体小鼠模型中进行研究。总之，这里提出的研究有望确定有效地针对急性髓细胞白血病细胞凋亡的新的联合疗法，目标是为患者带来更具穿透性和持久性的疗法。

 DESCRIPTION (provided by applicant): Despite continued interest in novel and repurposed small molecule inhibitors, the standard of care for adult patients diagnosed with de novo acute myeloid leukemia (AML) has remained largely unchanged over the last three decades. Recent developments have shed light on the dependence of AML cells on the antiapoptotic protein BCL-2, revealing a molecular dependency that can be exploited. Concurrently, a class of targeted therapies, termed BH3 mimetics, have been developed for the purpose of inhibiting antiapoptotic BCL-2 family proteins. One of these agents, ABT-199, is a specific inhibitor of BCL-2 and is moving into phase III clinical trials for treatment of AML. Given that all targeted therapies to date are subject to resistance, it is not surprising that AML cells are capable of acquiring resistance to ABT-199. Recently, we used a pathway-centric, gain-of-function screen to nominate MCL-1 and BCL-XL as major drivers of resistance to ABT-199 in AML. Further, we demonstrated that one or both proteins were upregulated in six independent ABT-199-resistant AML cell lines derived through chronic drug exposure and that co-targeting these proteins with ABT-199 can delay or even forestall the onset of acquired resistance. Presently, however, our ability to directly target these proteins is limited by the lack of potent and orally bioavailable compounds. In the proposed work, we will use both pharmacological, candidate-based methods and unbiased, CRISPR/Cas9-based screens to identify therapeutic targets that enhance the activity of ABT-199 in AML through their inhibition of BCL-XL and MCL-1. Hits from these assays will be credentialed through a series of computational and in vitro approaches to identify those combinations with greatest translational potential, and these lead combinations will subsequently be studied in an in vivo murine model of AML. Together, the studies proposed here promise to identify new combination therapies that efficiently target apoptosis in AML with the goal of leading to more penetrant and durable therapies for patients