Molecular Combinatorial Therapy of Glioblastoma Multiforme

描述（由申请人提供）：分子靶向蛋白细胞毒素治疗多形性胶质母细胞瘤（GBM）的临床应用取得了实质性进展。就新型抗癌药物而言，一些细胞毒素从实验室到临床的进展相对较快，这些研究带来了宝贵的转化信息。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效用有关。一是目标特异性。影响细胞毒素疗效的另一个因素是可以预测对细胞毒素有反应的患者群体的相对百分比。第三个因素，使用对流增强递送（CED）将细胞毒素直接有效地递送到肿瘤部位，在许多情况下已被证明是有效的，但通常没有监测到。这些假设将通过实验来解决，因为我们拥有这样做所需的所有工具。在靶向特异性方面，我们发现绝大多数GBM患者过表达白细胞介素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GBM标本和细胞系中被发现升高，但在正常脑中没有。一种靶向EphA2的细胞毒素原型已经成功生成。关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的过表达，因此这是一个理想的情况，所有患者都可以预测有反应或有资格接受治疗。关于重组细胞毒素给药GBM的研究表明，使用钆和标记的人血清白蛋白（HSA）可以获得通过CED的药物分布的可靠监测。此外，一些品种的狗表达的分子指纹与人类GBM相似，代表了一种有吸引力的人类疾病的大型动物临床前模型；CED已经被应用于狗的中枢神经系统。因此，本文提出了三个具体目标。具体目标#1是优化一种新的分子靶向抗GBM药物，利用EphA2受体在GBM中的特异性过表达。我们将继续研究一种以ephrina1为基础的含有细菌毒素的细胞毒素，这种细胞毒素具有强效和特异性的GBM细胞杀伤作用。具体目标2是探索细胞毒素联合靶向EphA2和IL- 13Ra2受体。该联合疗法将在体外和体内人体GBM模型中进行抗肿瘤疗效测试。在Specific Aim #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。通过MRI和PET以及Gd-HSA和[68]Ga-HSA分别监测CED递送药物的长期和短期分布。这个项目的结果将允许重组细胞毒素进一步成功的临床应用，这是一种非常有前途的抗gbm药物。

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.