Targeting invasion and DNA DSB repair in glioma with a multi-pronged approach.

描述(申请人提供)：我们最近证明ATM抑制剂(ATMI)KU-60019是一种有效的放射增敏剂，这是关于这种新化合物的第一篇报道。简而言之，KU-60019是一种非常特异的ATMK抑制剂，优于其前身KU-55933，在体外显示出至少10倍于放射增敏人胶质瘤细胞的效果。此外，通过AKT和ERK通路的促生存信号也被KU-60019抑制。ATMI的作用与PTEN和P53的状态无关。我们的研究还表明，在ATMI存在的情况下，胶质瘤细胞在体外的迁移和侵袭受到很大程度的抑制，可能是通过干扰AKT和ERK信号转导。因此，KU-60019作为基底膜放射增敏剂的潜在益处不仅限于其阻断DDR和有效地放射增敏胶质瘤细胞的能力，而且还具有抑制肿瘤侵袭和扩散的能力。KU-60019作为神经胶质瘤放射增敏剂的临床前试验正在进行中。我们现在想要确定PARP抑制剂(PARPI)AZD2281/KU-59436单独与KU-60019和/或放射联合使用是否会在临床前胶质瘤模型中显示出更好的治疗效果。AZD2281靶向并杀死BRCA1/BRCA2突变的肿瘤细胞，或在复制过程中未能修复DNA双链断裂(DSB)的同源重组修复(HRR)缺陷的细胞。因此，即使在没有辐射的情况下，AZD2281和KU-60019处理的胶质瘤细胞在DNA合成过程中也应该发生协同杀伤。低剂量辐射(d2Gy射线)可增强对AZD2281和KU-60019细胞的毒性，并进一步增加对S期细胞的杀伤作用和促进放射增敏作用。事实上，我们的初步数据显示，这种多管齐下的方法在共培养中杀死人类胶质瘤细胞，对正常细胞几乎没有毒性。因此，在动物胶质瘤模型中对这一策略进行原则证明测试是必要的。除了干细胞和神经前体细胞(NPs)外，大脑主要由不会增殖的终末分化细胞组成。因此，位于脑实质的侵袭性生长的胶质脑瘤将非常有利于AZD2281联合ATMI的治疗干预，辐射可能提供进一步的增强。然而，非常重要的是要研究这种治疗可能会对NPs产生什么影响，以便采取适当的步骤来保护正常的大脑。人们对正常大脑对辐射的反应所发生的分子过程知之甚少，但一般认为，神经干细胞的辐射会由于辐射、迟发效应和炎症而导致神经发生受损。我们希望，从拟议的动物研究中获得的见解将证明治疗GBM的一种新的药物组合策略是有效和安全的，并且在Kudos制药公司/阿斯利康的全力支持下，可以相对较快地转化为临床试验。 公共卫生相关性：多形性胶质母细胞瘤(GBM)的标准治疗充其量可以将患者的生存期延长一年多一点。因此，非常需要开发和测试新的治疗方法来对抗这种可怕的疾病。我们已经开发了一种针对侵袭、有利于生存的信号以及DNA修复的多管齐下的策略来治疗GBM，现在建议在动物模型中测试这种方法的原理证明。

DESCRIPTION (provided by applicant): We recently showed that the ATM inhibitor (ATMi), KU-60019, is a potent radiosensitizer, the first report published on this novel compound. Briefly, KU-60019 is a very specific ATM kinase inhibitor and superior over its predecessor KU-55933 and shows at least 10-fold better efficacy in vitro for radio sensitizing human glioma cells. In addition, pro-survival signaling through the AKT and ERK pathways is also inhibited by KU-60019. The ATMi does so irrespective of PTEN and p53 status. Our studies also showed that glioma cells migration and invasion in vitro were inhibited to a large extent perhaps by interfering with AKT and ERK signaling in the presence of ATMi. Thus, the potential benefit of KU-60019 as a radiosensitizer for GBM is not limited to its ability to block the DDR and potently radiosensitize glioma cells but also having the ability to inhibit invasion and spread of the cancer. Preclinical testing of KU-60019 as a radiosensitizer for glioma is ongoing. We would now like to determine whether the PARP inhibitor (PARPi) AZD2281/KU-59436 alone, in combination with KU-60019 and/or radiation would show improved therapeutic efficacy in a preclinical glioma model. AZD2281 targets and kills tumor cells with mutations in BRCA1/BRCA2, or cells that are defective in homologous recombination repair (HRR) failing to repair DNA double-strand breaks (DSBs) during replication. Thus, synergistic killing should occur in glioma cells treated with AZD2281 and KU-60019 during DNA synthesis even in the absence of radiation. Low dose radiation (d 2 Gy) is expected to enhance the toxicity to AZD2281 and KU-60019 and further increase killing and promote radiosensitization of cells in S-phase, the most radioresistant cell cycle phase. In fact, our preliminary data show that this multi-pronged approach kills human glioma cells with little to no toxicity to normal cells in co-cultures. Thus, proof-of-principle testing of this strategy in an animal glioma model is warranted. Except for stem cells and neural progenitors (NPs), the brain consists mostly of terminally differentiated cells that do not proliferate. Thus, aggressively growing glial brain tumors residing in the brain parenchyma would be very favorable for therapeutic intervention with AZD2281 in combination with the ATMi with radiation perhaps providing further potentiation. However, it is very important to examine what impact this treatment might have on the NPs so that appropriate steps can be taken to spare normal brain. Little is known about the molecular processes occurring in normal brain in response to radiation but in general it is believed that radiation of neural stem cell compartments results in impaired neurogenesis due to radiation late effects and inflammation. We hope that insights gained from the proposed animal studies will demonstrate proof-of-principle of a novel drug combination strategy for the treatment of GBM that would be effective and safe and with the full support of KuDOS Pharmaceuticals/AstraZeneca can relatively quickly be translated into a clinical trial. PUBLIC HEALTH RELEVANCE: At best, standard treatment of glioblastoma multiforme (GBM) prolongs patient survival by a little more than a year. Thus, there is great need for developing and testing novel therapeutic approaches to combat this dreadful disease. We have developed a multi-pronged strategy targeting invasion, pro-survival signaling as well as DNA repair for treating GBM and now propose to test this approach for proof-of-principle in an animal model.