Targeted Therapy for AML Stem Cells

描述（由申请人提供）：每年约有12，000名新的AML患者被诊断出来，9，000人死于AML复发和/或治疗毒性。开发新型、靶向和更安全的AML疗法的需求尚未得到满足。在所有成人AML中，约50%具有正常核型（NK），其中三分之一表达具有内部串联重复（ITD）的FLT 3，这与不良临床结局相关。AML干细胞/早期祖细胞能够无限自我更新和增殖，并且是相对难治的。经典的WNT-β-连环蛋白通路对于AML干/祖细胞的自我更新、生长和存活至关重要。在AML中，失调的WNT信号传导抑制<$-连环蛋白的降解，导致<$-连环蛋白与二分TCF/LEF转录因子的核定位和相互作用增加。这导致参与AML干/祖细胞生长和存活的基因上调。衔接蛋白TBL 1（转导蛋白样蛋白1）是连环蛋白介导的靶基因转录所必需的， 促进AML表型。我们的初步研究表明，BC 2059（<$-Cat Pharmaceuticals）是一种新型小分子蒽醌肟类似物，可有效破坏TBL 1与<$-连环蛋白的结合，促进蛋白酶体降解<$-连环蛋白。这代表了一种新的和创新的方法，以减弱核水平和转录活性的连环蛋白。我们的初步研究结果还表明，BC 2059对培养的和原代人NK-AML原始祖细胞（BPC）（包括表达FLT 3-ITD的细胞）发挥体外和体内抗AML活性，而不诱导宿主毒性。此外，我们的初步研究表明，与组蛋白脱乙酰酶抑制剂（HDI）帕比司他（PS）或FLT 3拮抗剂AC-220的共处理增强了BC 2059诱导的人AML BPC的凋亡。因此，我们建议检验BC 2059介导的ω-连环蛋白水平/活性敲低将与组蛋白脱乙酰酶抑制剂（HDI）协同相互作用的假设。 或FLT 3拮抗剂对有或无（w/wo）FLT 3-ITD的AML发挥抗AML功效。目的1：进一步阐明BC 2059在体外培养和原代人AML BPC中的生长抑制、分化和凋亡作用及其潜在机制，并评估BC 2059在小鼠模型中对已建立的人AML的体内疗效。目的2：确定BC 2059和HDI联合治疗对人AML BPC的体外和体内疗效。目标3：确定BC 2059和FLT 3拮抗剂对表达FLT 3-ITD的培养和原代人AML BPC的体外和体内抗AML疗效。这些临床前研究将生成支持性体外和体内数据，作为基于BC 2059的AML治疗（不表达FLT 3-ITD）临床转化的概念验证。

DESCRIPTION (provided by applicant): Approximately 12,000 new patients of AML are diagnosed each year and 9,000 die due to AML relapse and/or toxicity of the therapy. There is an unmet need to develop novel, targeted and safer therapies for AML. Of all adult AML, approximately 50% have normal karyotype (NK) and one-third of these express FLT3 with internal tandem duplication (ITD), which is associated with a poor clinical outcome. AML stem/early progenitor cells are capable of limitless self-renewal and proliferation, and are relatively treatment-refractory. The canonical WNT- ¿-catenin pathway is essential for self-renewal, growth and survival of AML stem/progenitor cells. In AML, deregulated WNT signaling inhibits degradation of ¿-catenin, causing increased nuclear localization and interaction of ¿-catenin with the bipartite TCF/LEF transcription factor. This results in up regulation of genes involved in the growth and survival of AML stem/progenitor cells. An adaptor protein TBL1 (Transducin ¿-like protein 1) is required for ¿-catenin mediated transcription of target genes that promote the AML phenotype. Our preliminary studies demonstrate that BC2059 (¿-Cat Pharmaceuticals), a novel, small molecule, anthraquinone oxime-analog, potently disrupts the binding of TBL1 with ¿-catenin, promoting the proteasomal degradation ¿-catenin. This represents a novel and innovative approach to attenuate the nuclear levels and transcriptional activity of ¿-catenin. Our preliminary findings also demonstrate that BC2059 exerts in vitro and in vivo anti-AML activity against cultured and primary human NK-AML blast progenitor cells (BPCs), including those expressing FLT3-ITD, without inducing host toxicity. Additionally, our preliminary studies show that co- treatment with the histone deacetylase inhibitor (HDI) panobinostat (PS) or FLT3 antagonist AC-220 enhances BC2059-induced apoptosis of human AML BPCs. Therefore, we propose to test the hypothesis that BC2059 mediated knockdown of ¿-catenin levels/activity would synergistically interact with a histone deacetylase inhibitor (HDI) or FLT3 antagonist in exerting anti-AML efficacy against AML with or without (w/wo) FLT3-ITD. The aims of the proposal are: AIM 1: To further elucidate the in vitro growth inhibitory, differentiation and apoptotic effects of BC2059, and the underlying mechanisms, in cultured and primary human AML BPCs, as well as evaluate the in vivo efficacy of BC2059 against established human AML in mouse models. AIM 2: To determine the in vitro and in vivo efficacy of co-treatment with BC2059 and HDI against human AML BPCs. AIM 3: To determine the in vitro and in vivo anti-AML efficacy of BC2059 and a FLT3 antagonist against cultured and primary human AML BPCs expressing FLT3-ITD. These pre-clinical studies will generate the supportive in vitro and in vivo data as proof-of-concept for the clinical translation of BC2059-based therapy for AML w/wo FLT3-ITD expression.