Suppression of BCR-ABL by siRNA-loaded Nanoparticles for the Treatment of CML

描述（由申请人提供）：慢性髓系白血病（CML）是一种造血细胞疾病，其中费城染色体的出现（染色体9和22的易位）导致融合癌蛋白BCR-ABL的表达，其酪氨酸激酶活性失调导致该疾病特征的髓系细胞异常生长。在过去的20年里，靶向BCR-ABL治疗CML取得了实质性进展；目前该疾病的治疗包括每日给予酪氨酸激酶抑制剂甲磺酸伊马替尼（格列卫）和/或几种第二代抑制剂（达沙替尼，尼洛替尼）。然而，对当前系列atp竞争性BCR-ABL抑制剂的耐药性增加，需要发现能够以高特异性靶向所有BCR-ABL蛋白的新疗法。最近，利用融合连接靶向小干扰RNA （siRNA）沉默BCR-ABL的潜力已在体外和离体实验中得到证实。这项技术可以用来设计一种强大的治疗方法，抑制所有活化Abl的变体，甚至是伊马替尼/达沙替尼耐药形式。但是，这种方法在体内基因沉默的进展需要开发优化连接靶向siRNA效率、特异性和递送的方法。本研究的目的1是设计一种有效的特异性连接靶向小沉默RNA来抑制BCR-ABL的主要转录本变体（b3a2），并应用技术将这种结构加载到聚合物纳米颗粒中进行递送。在目标2中，将探索利用微尺度流体通过表面修饰来增强聚合纳米颗粒向白血病细胞的递送的策略

DESCRIPTION (provided by applicant): Chronic Myeloid Leukemia (CML) is a disorder of hematopoietic cells wherein the appearance of the Philadelphia chromosome (a translocation of chromosomes 9 and 22) results in expression of the fusion oncoprotein BCR-ABL, whose disregulated tyrosine kinase activity causes the abnormal myeloid cell growth characteristic of the disease. In the last 20 years, substantial advances have been made in targeting BCR-ABL therapeutically to treat CML; current therapy for the disease involves daily administration of the tyrosine kinase inhibitor Imatinib Mesylate (Gleevec) and/or several second-generation inhibitors (Dasatinib, Nilotinib). However, increasing resistance to the current line of ATP-competitive inhibitors of BCR-ABL warrants discovery of novel therapeutics that can target all BCR-ABL proteins with high specificity. Recently the potential of using fusion junction-targeted small interfering RNA (siRNA) to silence BCR-ABL has been demonstrated in vitro and ex vivo. This technology could be used to design a powerful line of therapeutics that suppresses all variants of activated Abl, even imatinib/dasatinib resistant forms. But advancement of this approach toward gene silencing in vivo requires developing methods for optimizing junction-targeted siRNA efficiency, specificity, and delivery. Aim 1 of this proposed research is to design a potent and specific junction-targeted small silencing RNA for suppression of the predominant transcript variant of BCR-ABL (b3a2) and to apply techniques to load this construct into polymeric nanoparticles for delivery. In Aim 2, strategies for enhancing delivery of polymeric nanoparticles to leukemic cells via surface modification will be explored using a micro-scale fluid flow device that mimics nanoparticle-cell interactions expected in the circulatory system. After optimization of the small silencing RNA and its delivery vehicle, Aim 3 seeks to assess the efficacy of the engineered therapeutic in a humanized mouse model of leukemia. Through these aims, significant progress will be made toward the discovery and optimization of an RNAi based therapeutic for more broad, but equally potent, treatment of CML.