Development of novel selective Rac inhibitors for refractory leukemias

项目摘要/摘要 Rac属于Rho GTP酶家族，是调节关键细胞的蛋白质 整合细胞外信号和协调下游激活的功能 效应器。在几种白血病模型(BCR-ABL、MLL-重排和RAS突变)中 白血病)，RAC被异常激活，其基因缺失可减弱 致癌基因的转化效应。此外，由于以下原因，RAC的激活增加 选择性剪接版本的表达或其编码序列的突变 已被证明在一些实体肿瘤的恶性进展中起着关键作用， 包括乳腺癌、肺癌和结肠癌以及黑色素瘤。由于它的生化特性 尽管RAC具有多种特性，但尚未被充分开发为癌症的治疗靶点。然而， 一种工具化合物(NSC 23766)，在高浓度时抑制Rac的激活 哺乳动物细胞之前已经被开发出来，可以抑制恶性转化 由bcr-abl介导的体内外。 在目前的项目中，在Rho GTP酶生物学方面处于领先地位的威廉姆斯实验室 造血干细胞，正在与Evotec合作(一家药物化学公司， 在药物发现方面拥有深厚的专业知识)，以采用正交方法开发小型 用于治疗难治性白血病的RAC分子抑制剂(特别是MLL- 重排和RAS突变)。我们提出了以下方法来确定新的 抑制剂，并将最近发现的化合物开发成铅分子： 1)对先导化合物DW_0069进行了优化 筛选RAC抑制剂。该化合物在体外和体内均能抑制Rac的激活 体内，在白血病异种移植模型中耐受性良好。我们已经确定了 几种效力更强的类似物。在这个项目中，我们建议进一步 对该化合物进行优化，并探讨其作用机理。 2)扩大基于片段的RAC抑制剂药物发现计划，以及 开发由基于片段的核磁共振屏幕识别的其他命中。 确定复合体开发优先顺序的标准将涉及延长的搜救研究， 良好的吸收、分布、代谢和排泄(ADME)特性和活性 在RAS突变和MLL重排的高级细胞和动物模型中 白血病。该项目提案包括提名先导化合物的时间表。 用于人体试验，以及拟议的第一阶段人体试验大纲。

Project summary/abstract Rac belongs to the family of Rho GTPases, proteins that regulate critical cellular functions by integrating extracellular signals and coordinating activation of downstream effectors. In several models of leukemia (BCR-ABL, MLL-rearranged and RAS-mutated leukemia), Rac is aberrantly activated and its genetic deletion can attenuate the transforming effect of driver oncogenes. Moreover, increased activation of Rac due to the expression of an alternative splicing version or to mutations in its coding sequence has been shown to play a critical role in the malignant progression of some solid tumors, including breast, lung and colon cancer as well as melanoma. Due to its biochemical properties, Rac has not been fully exploited as a therapeutic target in cancer. However, a tool compound (NSC 23766) that inhibits Rac activation at high concentration in mammalian cells has been previously developed and inhibits malignant transformation mediated by BCR-ABL in vitro and in vivo. In the present project, the Williams laboratory, a leader in Rho GTPase biology in hematopoietic stem cells, is partnering with Evotec (a medicinal chemistry company with deep expertise in drug discovery) to carry out orthogonal approaches to develop small molecule inhibitors of Rac for the treatment of refractory leukemias (in particular, MLL- rearranged and RAS-mutated). We propose the following approaches to identify new inhibitors and develop recently identified compounds into lead molecules: 1) Optimization of DW_0069, the lead compound previously identified by a virtual screening for Rac inhibitors. This compound inhibits Rac activation in vitro and in vivo, and is well tolerated in leukemia xenograft models. We have already identified several analogues with increased potency. In this project, we propose to further optimize this compound and to investigate its mechanism of action. 2) Expansion of a fragment-based drug discovery program for Rac inhibitors, and development of additional hits identified by a fragment-based NMR screen. Criteria for prioritization of compound development will involve extended SAR studies, good absorption, distribution, metabolism, and excretion- (ADME) properties, and activity in advanced cellular and animal models of RAS-mutated and MLL-rearranged leukemias. The project proposal includes a timeline for nomination of lead compounds for human testing and an outline of a proposed phase I human trial.