Molecular Combinatorial Therapy of Glioblastoma Multiforme

描述(申请人提供)：分子靶向蛋白类细胞毒素在治疗多形性胶质母细胞瘤(GBM)的临床应用方面取得了实质性进展。一些细胞毒素的进展相对较快，就像新型抗癌药物一样，从试验台到临床，这些研究带来了宝贵的翻译信息。根据临床试验和实验室研究，我们假设有三个重要因素与细胞毒素的整体临床用途有关。其一是靶标的特异性。另一个影响细胞毒素疗效的因素是可以预测的对细胞毒素有反应的患者群体的相对百分比。第三个因素是，使用对流增强递送(CED)将细胞毒素直接高效地递送到肿瘤部位已被证明在许多情况下是有效的，但通常没有监测。这些假设将在实验中解决，因为我们拥有这样做所需的所有工具。关于靶点特异性，研究发现绝大多数GBM患者过度表达IL-13(IL-13)、IL-13Ra2的结合位点。此外，另一种受体EphA2酪氨酸激酶受体在大量的GBM标本和细胞系中被发现升高，但在正常脑中不表达。已成功制备了针对EphA2的细胞毒素原型。对于对细胞毒素有潜在反应的患者群体，几乎100%的GBM患者同时存在IL-13Ra2和EphA2的过度表达，因此这是一个理想的情况，在这种情况下，所有患者都可以预测到有反应或有资格接受治疗。关于重组细胞毒素向GBM的传递，研究表明，使用Gd和标记的人血清白蛋白(HSA)可以真实地监测药物通过CED的分布。此外，一些品种的狗表现出类似于人类GBM的分子指纹，代表了一种有吸引力的大型动物临床前人类疾病模型；CED已经应用于狗的中枢神经系统。因此，提出了三个具体目标。具体目标#1是优化一种新型的分子靶向抗GBM药物，该药物利用GBM中EphA2受体的特异性过表达。我们将继续研究一种基于ewitinA1的细菌毒素，它含有细胞毒素，显示出强大和特异的GBM细胞杀伤能力。具体目标2是探索EphA2和IL-13Ra2受体与细胞毒素的联合靶向。这种联合疗法将在人体GBM的体外和体内模型中测试抗肿瘤效果。在具体目标#3中，将使用组合重组细胞毒素方法对患有恶性胶质瘤的狗进行I期临床试验。CED释放药物的分布将通过使用MRI和PET以及分别使用Gd-HSA和[68]Ga-HSA进行长期和短期监测。该项目的结果将使重组细胞毒素进一步成功地应用于临床，这是一类非常有前途的抗基底膜药物。 公共卫生相关性：大多数脑部恶性肿瘤，包括多形性胶质母细胞瘤(GBM)，仍然无法治愈，因此在医学上代表着未得到满足的需求。我们已经找到了一种结合有效的肿瘤细胞杀伤剂来靶向肿瘤细胞的方法，这种方法适用于几乎所有的GBM患者。我们还在努力以一种受控的方式将这些药物输送到脑瘤。预计这种方法将对GBM患者的总体生存产生影响。

DESCRIPTION (provided by applicant): There has been a substantial progress in clinical application of molecularly targeted proteinaceous cytotoxins for the treatment of glioblastoma multiforme (GBM). Several cytotoxins have moved relatively quickly, as for novel anti-cancer drugs, from bench to clinic and these studies brought invaluable translational information. Based on clinical trials and laboratory research, we hypothesize that there are three important factors linked to the overall cytotoxins' clinical utility. One is the target specificity. Another factor impacting efficacy of cytotoxins is the relative percentage of patients' population that can be predicted to be the responders to a cytotoxin. And the third factor, an efficient delivery of the cytotoxin directly to the tumor site using convection-enhanced delivery (CED) has been proven to be effective in many cases, but it is ordinarily not monitored. These hypotheses will be tackled experimentally, since we have all the tools needed to do so. With regard to target specificity, it was found that a vast majority of GBM patients over-express binding sites for interleukin 13 (IL-13), IL-13Ra2. Furthermore, another receptor, EphA2 tyrosine kinase receptor, was found to be elevated in a large number of GBM specimens and cell lines, but not in normal brain. A prototype cytotoxin targeting EphA2 has been successfully generated. With regard to the population of patients being potential responders to the cytotoxins, over-expression of IL-13Ra2 and Epha2 together is present in almost 100% of patients with GBM and thus it is an ideal situation in which all patients could be predictably responders or eligible for treatment. With regard to recombinant cytotoxins' delivery to GBM, it was demonstrated that using gadolinium and labeled human serum albumin (HSA) a faithful monitoring of drug distribution through CED can be obtained. In addition, some breeds of dogs express molecular fingerprints similarly to human GBM and represent an attractive, large animal pre-clinical model of human disease; the CED has already been applied to the central nervous system of dogs. Therefore, three Specific Aims are proposed. Specific Aim #1 is to optimize a novel molecularly targeted anti-GBM agent that exploits specific over-expression of EphA2 receptor in GBM. We will continue the work on an ephrinA1-based bacterial toxin-containing cytotoxin that exhibit potent and specific GBM cell killing. Specific Aim #2 is to explore combinatorial targeting of EphA2 and IL- 13Ra2 receptors with the cytotoxins. The combination therapy will be tested for an anti-tumor efficacy in in vitro and in vivo models of human GBM. In Specific Aim #3, Phase I clinical trial in dogs with malignant gliomas using combinatorial recombinant cytotoxins approach will be performed. The distribution of the CED- delivered drugs will be monitored long- and short-term by employing MRI and PET and using Gd-HSA and [68]Ga-HSA, respectively. The results of this project will permit further successful clinical application of recombinant cytotoxins, a highly promising class of anti-GBM drugs. PUBLIC HEALTH RELEVANCE: Most malignant tumors of the brain, including glioblastoma multiforme (GBM) remain incurable and thus represent unmet need in medicine. We have found a way to target specifically tumor cells with potent tumor cell killing agents in combination that would be applicable to almost all patients with GBM. We are also working on a controlled way to deliver these agents to brain tumors. It is expected that this approach will have impact on the overall survival of patients with GBM.