Targeted Therapy for AML Stem Cells

描述(由申请人提供)：每年约有12,000名新确诊的急性髓细胞白血病患者，其中9,000人死于急性髓细胞白血病复发和/或治疗的毒性。为急性髓细胞白血病开发新颖、有针对性和更安全的治疗方法是一个尚未得到满足的需求。在所有成人AML中，约50%具有正常核型(NK)，其中三分之一表达Flt3并伴有内部串联重复(ITD)，这与不良的临床结局有关。急性髓系白血病干细胞/早期祖细胞具有无限的自我更新和增殖能力，且相对耐药。规范的WNT-β-连环蛋白通路对于AML干/祖细胞的自我更新、生长和存活是必不可少的。在AML中，失控的WNT信号抑制了β-catenin的降解，导致β-catenin的核定位增加，并与两部分Tcf/Lef转录因子相互作用。这导致参与AML干细胞/祖细胞生长和存活的基因上调。连接蛋白介导的靶基因转录需要接头蛋白TBL1(转导素样蛋白1)。 推广AML表型。我们的初步研究表明，BC2059(？-Cat PharmPharmticals)是一种新型的小分子类似物，它能有效地破坏TBL1与？-连环蛋白的结合，促进蛋白酶体降解-连环蛋白。这代表了一种新颖和创新的方法来减弱连环蛋白的核水平和转录活性。我们的初步研究结果还表明，BC2059在体外和体内对培养和原代培养的人NK-AML原始祖细胞(BPC)具有抗AML活性，包括表达Flt3-ITD的BPC，而不会引起宿主毒性。此外，我们的初步研究表明，与组蛋白去乙酰酶抑制剂(HDI)Panobinostat(PS)或Flt3拮抗剂AC-220共同处理可增强BC2059诱导的人AML BPC的凋亡。因此，我们建议检验这样一种假设，即BC2059介导的连环蛋白水平/活性的下调将与组蛋白脱乙酰酶抑制剂(HDI)协同作用。 或Flt3拮抗剂对有或无(w/wo)Flt3-ITD的AML发挥抗AML作用。本研究的目的是：1.进一步阐明BC2059在体外对培养和原代培养的人AML BPC的生长抑制、分化和凋亡作用及其机制，并在小鼠模型中评价BC2059对已建立的人AML的体内疗效。目的：检测BC2059联合HDI对人急性髓系白血病(AML)BPC的体内外效应。目的：检测BC2059和Flt3拮抗剂对培养和原代表达Flt3-ITD的人AML BPC的体内外抗AML作用。这些临床前研究将产生支持性的体外和体内数据，作为基于BC2059的AML治疗方法临床翻译的概念验证。

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.