Novel Substrate Competitive Bcr-Abl Inhibitor Active Against Gleevec-Resistant CM

伊马替尼是一种BCR-ABL酪氨酸激酶抑制剂，用于治疗人CML， 取得了巨大的成功然而，很大一部分长期接受 伊马替尼由于BCR-ABL激酶结构域的突变而产生耐药性。 最近开发了一种化合物（ON 012380），其在不同于伊马替尼的位点与BCR-ABL结合， 在5-10 nM的浓度下诱导Ph+ CML细胞的凋亡（其效力是对照的10-50倍）。 伊马替尼）。更有趣的是，这种化合物被发现是非常有效的诱导死亡的所有 对伊马替尼耐药的CML突变体。在本申请中，我们建议进行一项 该化合物作用机制的详细生化表征和 受这种化合物影响的信号通路。目标是：1.为了确定 通过ON 012380抑制BCR-ABL并进行诱变BCR-ABL克隆体外筛选， 获得可能影响ON 012380结合的氨基酸取代的理解。 2.确定ON 012380对（a）BCR-ABL野生型和伊马替尼耐药突变体的影响 对激酶活性的影响;（B）下游信号传导，如MAPK、AKT和STATS活化;（c）细胞 周期进展;和（d）在表达野生型CD 4 + T细胞的肿瘤细胞中激活的凋亡途径的性质 或突变BCR-ABL蛋白。3.确定ON 012380是否诱导Lynoverexpressing的细胞死亡， 伊马替尼耐药细胞，如果是，确定作用机制。4.进行药代动力学研究 通过用于功效研究的途径和时间表，和5.在已建立的异种移植物中进行疗效试验 CML模型

Imatinib, which is an inhibitor of BCR-ABL tyrosine kinase and used for the treatment of human CML, has been a spectacular success. However, a significant proportion of patients chronically treated with imatinib develop resistance due to acquisition of mutations in the kinase domain of BCR-ABL. We have recently developed a compound (ON012380) that binds to BCR-ABL at a site different from imatinib and induces apoptosis of Ph+ CML cells at a concentration of 5-10 nM (which is 10-50 fold more potent than imatinib). More interestingly, this compound was found to be very effective in inducing the death of all of the imatinib-resistant mutants of CML identified so far. In this application, we propose to carry out a detailed biochemical characterization of the mechanism of action of this compound and the nature of signaling pathways that are affected by this compound. The aims are:1. To determine the kinetics of inhibition of BCR-ABL by ON012380 and carry out in vitro screen of mutagenizedBCR-ABL clones to gain an understanding of the amino acid substitutions that are likely to imapir the binding of ON012380. 2. To determine the effects of ON012380 on (a) wild-type and imatinib-resistant mutants of BCR-ABL on the kinase activity; (b) downstream signaling such as MAPK, AKT and STATS activation (c) cell cycle progression; and (d) the nature of apoptotic pathways activated in tumor cells that express wild-type or mutant BCR-ABL protein. 3. Determine whether ON012380 induces cell death of Lynoverexpressing, imatinib resistant cells and if so, determinethe mechanismof action. 4. Conduct pharmacokinetic studies by the route and schedule used for efficacy studies, and 5. Conduct efficacy trials in established xenograft models of CML.