Targeting Ral GTPases in Bladder Cancer

转移性膀胱癌（BC）治疗的最后一个重大进展发生在1997年， 吉西他滨的出现尽管有这种进展，内脏转移通常是致命的。的总体目标 所提议的研究是开发阻断转移过程中的关键节点的小分子抑制剂。 我们发现Rai GTP酶作为一个治疗上易处理的信号通路的分子开关 使UC细胞在肺中生长，肺是最常见的内脏转移部位。其临床意义 Rai作为治疗靶点的有效性得到了以下结果的支持： 肿瘤使患者处于更高的转移风险和肺转移对Rai表达的需求。 在UC的动物模型中发生转移。我们对这个应用程序的指导假设是， 靶向Rai的分子为转移性UC提供了有效的治疗。在医学博士安德森的支持下 膀胱孢子发育研究计划（DRP），我们评估了> 500 K化合物的能力， 在计算和组合筛选中结合RalA或RalB，并选择99个“命中”。这些是 在一系列二级测定中进行评估，允许我们选择Rai结合化合物（RUC）8和10， 在这个应用程序中。选择RUC 8和10是因为它们：1）抑制RalA与RalBPI的结合， 人UC细胞和RalA诱导的在鼠胚胎成纤维细胞中的扩散; 2）抑制体外单层 人UC细胞的生长（IC 50 0.5-1.9 pM）; 3）通过核磁共振（NMR）直接结合RalB 光谱学;和4）在小鼠中具有良好的药代动力学（PK）性质（Cmax 1.3-23 pM，T1/2 3.7-4.6 小时）。为了开发这类新的代理，我们提出了以下具体目标：目标1：表征 基于RUC 8和10的更高效力的第二代化合物，使用药物化学，计算 基于片段的设计和化学数据库的相似性搜索。在不太可能的情况下， 目标1中没有发现有效化合物，我们将使用RUC 8和10追求目标2和3，因为它们 足够的IC 50和体内PK。目的2：评价2””代化合物的体内治疗作用 在内脏转移的新型人类UC模型中的功效。目标3：开发预测性生物标志物 在人体组织中对antlRal疗法的反应，这将使我们在今年年底前进入1期试验。 项目阿斯利康对我们工作的兴趣记录提高了整体成功的机会， 将我们的新型Rai抑制剂转化为抗癌治疗剂的临床环境。

The last major advance in the treatment of metastatic bladder cancer (BC) took place in 1997 with the advent of gemcitabine. Despite this advance, visceral metastases are usually fatal. The overall goal of the proposed studies is to develop small molecule inhibitors that block a critical node in the metastatic process. We found that Rai GTPases serve as the molecular switches of a therapeutically tractable signaling pathway that allows UC cells to grow in the lung, the most common visceral metastatic site. The clinical significance of this pathway and validity of Rai as a therapeutic target is supported by finding that high Rai expression in tumors places patients at higher risk for metastasis and the requirement of Rai expression for lung metastasis to occur in animal models of UC. Our Guiding Hypothesis for this application is that small molecules targeting Rai provide effective therapy for metastatic UC. With support from the MD Anderson Bladder SPORE Developmental Research Program (DRP), we evaluated >500K compounds for their ability to bind RalA or RalB in computational and combinatorial screens and selected 99 "hits". These were evaluated in a series of secondary assays allowing us to select Rai Binding Compound (RUC)8 and 10 to be pursued in this application. RUC8 and 10 were selected because they: 1) inhibit RalA to RalBPI binding in human UC cells and RalA induced spreading in murine embryo fibroblasts; 2) inhibit in vitro monolayer growth (IC50 0.5-1.9 pM) of human UC cells; 3) bind RalB directly by nuclear magnetic resonance (NMR) spectroscopy; and 4) have good pharmacokinetic (PK) properties in mice (Cmax 1.3-23 pM, T1/2 3.7-4.6 hrs). To develop this novel class of agents we propose the following Specific Aims: Aim 1: Characterize higher potency 2"^* generation compounds based on RUC8 and 10 using medicinal chemistry, computational fragment-based design, and similarity search of chemical databases. In the unlikely situation that higher potency compounds are not found in Aim 1, we will pursue Aim 2 and 3 using RUC8 and 10, given their adequate IC50 and in vivo PK. Aim 2: Evaluate 2"" generation compounds for their in vivo therapeutic efficacy in novel human UC models of visceral metastasis. Aim 3: Develop predictive biomarkers of response to antlRal therapeutics in human tissues that will position us for Phase 1 trials by end of this project. Documented interest by Astra Zeneca in our work improves overall chances for success in translating our novel Rai inhibitors into the clinical setting as anticancer therapeutics.