Development of Trabectedin Analogs that Target the EWS-FLI1 Transcription Factor

 描述(申请人提供)：尤文肉瘤是一种骨和软组织肿瘤，预后很差，特别是对于复发或转移性疾病的患者，其总存活率不到30%。自目前采用的5种药物化疗方案建立以来的25年里，患者的生存几乎没有改善，治疗方法也没有改变。因此，迫切需要新的化合物和方法，直接针对尤文肉瘤细胞存活的基因。这项提议的目标是建立一种以抑制这种肿瘤的决定性分子特征--EWS-FLI1转录因子为中心的治疗方法。尤文肉瘤的生存完全依赖于EWS-FLI1的持续表达。这种致癌转录因子改变了500多个基因的表达，创建了负责尤文肉瘤细胞持续增殖、耐药甚至转移的转录程序。靶向EWS-FLI1的挑战是该蛋白是一种转录因子，人们普遍认为它是一个“无法下药的靶点”。在这项建议中，我们采用床边到板凳再回来的方法来开发一种以EWS-FLI1为靶点的疗法，使用一种名为Trabectedin的化合物作为主干。在早期的I期研究中，用曲贝替丁治疗的一名尤文肉瘤患者对这种药物完全有效。与这一结果一致，我们之前已经证明Trabectedin干扰EWS-FLI1转录因子的活性。不幸的是，一项后续的II期试验没有证实TH药物对尤文肉瘤的活性。在这项建议中，我们假设尤文肉瘤患者在II期研究中对Trabectedin没有反应是由于药物的治疗指数较差，将Trabectein的暴露限制在不足以阻断EWS-FLI1的水平。我们认为，限制这些血清水平的药物相关毒性是在正常细胞和尤文肉瘤细胞中引起毒性的附带DNA损伤。因此，为了与NIH了解极端临床应答者的倡议保持一致，在这个 根据该提案，我们将对82个曲贝替丁类似物进行评估，以确定具有改进的治疗指数的化合物(S)，该指数将允许阻断患者的EWS-Fli 1。在这个过程中，我们将确定药物是如何作用于阻断EWS-FLI1活性的，以及药物相关的DNA损伤对这一活性的相对贡献是什么。最后，我们将提出一种新的联合疗法，通过改进EWS-FLI1抑制，将药物相关的DNA损伤集中在尤文肉瘤细胞上。总之，这些结果将为以EWS-FLI1阻断为中心的以Trabectedin为基础的疗法的临床翻译提供基础，以提高患者的存活率。

 DESCRIPTION (provided by applicant): Ewing sarcoma is a bone and soft tissue tumor with a poor prognosis, particularly for patients with relapsed or metastatic disease, where overall survival is less than 30%. In the last 25 years since the establishment of the currently employed 5-drug chemotherapeutic regimen, there has been very little improvement in survival and no change in the therapy for patients with this disease. Therefore, there is a great need for new compounds and approaches that directly target the genes responsible for Ewing sarcoma cell survival. The goal of this proposal is to build a therapy centered on the suppression of the defining molecular feature of this tumor, the EWS-FLI1 transcription factor. Ewing sarcoma absolutely depends on continued expression of EWS-FLI1 for cell survival. This oncogenic transcription factor alters the expression of more than 500 genes to create the transcriptional program responsible for the continued proliferation of Ewing sarcoma cells, drug resistance and even metastasis. The challenge in targeting EWS-FLI1 is that the protein is a transcription factor and widely believed to be an "undruggable target". In this proposal, we employ a bedside-to-bench and back again approach to develop a therapy that targets EWS-FLI1 using a compound called trabectedin as the backbone. In an early phase I study, a patient with Ewing sarcoma treated with Trabectedin achieved a complete response to this drug. Consistent with this result, we have previously shown that trabectedin interferes with the activity of the EWS-FLI1 transcription factor. Unfortunately, a follow-up phase II trial did not confirm that activity of th drug in Ewing sarcoma. In this proposal, we hypothesize that the failure of Ewing sarcoma patients to respond to the trabectedin in the phase II study was due to a poor therapeutic index of the drug that limited the exposure of trabectedin to levels that were not high enough to block EWS-FLI1. We believe that the drug associated toxicity that limited these serum levels was the collateral DNA damage that caused toxicity in normal cells as well as Ewing sarcoma cells. Therefore, in keeping with the NIH initiative of understanding extreme clinical responders, in this proposal, we will evaluate 82 analogs of trabectedin to identify compound(s) with an improved therapeutic index that will allow the blockade of EWS-FLI1 in patients. In the process, we will establish exactly how the drug works to block EWS-FLI1 activity and what the relative contribution of the drug associated DNA damage is to this activity. Finally, we will propose a novel combination therapy with improved EWS-FLI1 suppression that focuses the drug associated DNA damage specifically on Ewing sarcoma cells. Together, these results will provide the basis for the clinical translation of a trabectedin- based therapy centered on EWS-FLI1 blockade to improve patient survival.