Therapeutic Exploitation of Mutant BRAF for Astrocytoma

突变 BRAF 对星形细胞瘤的治疗利用

基本信息

批准号：
8584135
负责人：
PETER J HOUGHTON
金额：
$ 31.9万
依托单位：
RESEARCH INST NATIONWIDE CHILDREN'S HOSP
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-07-01 至 2018-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8584135
关键词：
Adult Astrocytoma BRAF gene Biological CDKN2A gene Cell Line Cells Cephalic Characteristics Child Childhood Childhood Astrocytic Tumor Childhood Solid Neoplasm Cisplatin Clinical Clinical Trials Cognitive deficits Cytotoxic agent DNA Damage DNA repair protein Data Dependence Development Disease Dose Drug Kinetics Drug resistance Etoposide Event Family member Genes Genetic Transcription Genomics Glioma Growth Factor Receptors Immune Induced Mutation Interleukin-6 Ionizing radiation JAK2 gene Juvenile Pilocytic Astrocytomas Lead MAP Kinase Gene MEK inhibition MEKs Malignant - descriptor Malignant Childhood Neoplasm Malignant Neoplasms Modeling Molecular Profiling Morbidity - disease rate Mus Mutate Mutation Neoplasm Metastasis Neurosecretory Systems Oncogenes Outcome PIK3CA gene PTEN gene Pathway interactions Patients Pediatric Brain Tumor Consortium Pediatric Neoplasm Pharmaceutical Preparations Pharmacotherapy Phase Physiological Population Progression-Free Survivals Radiation Toxicity Radiation therapy Radio Rare Diseases Recurrence Refractory Regulation Reporting Residual Tumors Resistance Resistance development Role STAT3 gene STK11 gene Signal Pathway Signal Transduction Survival Rate Testing Therapeutic Translations Vascular Diseases Visual Xenograft procedure base chemotherapy clinical application conventional therapy drug sensitivity effective therapy fusion gene gain of function gain of function mutation in vivo inhibitor/antagonist killings mutant neoplastic cell novel outcome forecast prevent public health relevance research clinical testing resistance mechanism subcutaneous therapeutic target tumor tumor xenograft

项目摘要

DESCRIPTION (provided by applicant): Low-grade astrocytomas (LGA) of childhood present a significant clinical challenge. While 5-year progression-free survival rate for chemotherapy plus radiotherapy is ~ 68%, significant morbidity is associated with the presence of residual tumor and the current therapy that includes neuroendocrine- cognitive deficits, visual deficits, vasculopathy and secondary tumors. Moreover, the metastatic potential and malignant transformation to a high-grade astrocytoma further contributes to the poor prognosis. Recent data show that BRAF is mutated in ~23% of LGA's, and 60% of xanthoastrocytomas. We have established two of the only childhood LGA models as direct patient- xenografts in mice. These tumors retain expression profiles and genomic alterations characteristic of the original patient's tumor, thus present unique models to develop alternative, less debilitating, curative therapy. BT-40 xenografts are heterozygous for mutated BRAF (V600E) whereas BT-35 xenografts have wild type BRAF. BT-40 tumors are exquisitely sensitive to the MEK inhibitor AZD6244, whereas BT-35 tumors are unresponsive, typical of other childhood tumor xenografts with wild type BRAF. Resistance to AZD6244 is characterized by an increase in the MEK-dependent gene signature, enhanced IL-6 transcription and secretion, and activation of STAT3 signaling. Resistance to AZD6244 is unstable, as tumors passaged in untreated mice revert to drug sensitivity, and correlates with decreased IL-6 and STAT3 activation. Further, two BRAF (V600E) mutant astrocytic cell lines intrinsically resistant to AZD6244 induce STAT3 activation as MEK is inhibited. The role of STAT3 activation in resistance will be studied in Aim 1. For BT-40 tumors sensitivity to AZD6244 is characterized by complete inhibition of TORC1 signaling, suggesting that mutant BRAF controls the PI3K/TORC1 signaling axis. The role of Akt and STAT3 signaling in MEK regulation of TORC1, and the simultaneous inhibition of MEK and STAT3 to prevent development of resistance, or reverse resistance to AZD6244, will be studied in Aim 2. We plan to exploit the control of mutant BRAF over TORC1 signaling therapeutically. In BT-40 xenografts, MEK inhibition leads to rapid and complete loss of the DNA repair protein FANCD2, downstream of TORC1, thus potentially selectively sensitizing tumor cells to cisplatin, etoposide and ionizing radiation. Further, we will test the concept that combination of cisplatin o etoposide with AZD6244 will prevent the emergence of AZD6244 resistant cells, as mutant BRAF is required to maintain Akt signaling associated with survival in cells exposed to cisplatin or etoposide. We will establish additional models of mutant BRAF LGA's, and determine whether results from BT-40 xenografts are generally applicable. These data will form the basis for rapid translation of novel non-genotoxic and also more conventional therapies that are both effective and less debilitating compared to current therapeutic approaches, for children with recurrent or surgically non-resectable LGA.

描述（由申请人提供）：儿童时期的低度星形细胞（LGA）提出了重大的临床挑战。虽然化学疗法和放射疗法的5年无进展生存率约为68％，但显着的发病率与残留肿瘤的存在以及包括神经内分泌认知缺陷，视觉缺陷，血管疾病和次要肿瘤的当前疗法有关。此外，向高级星形胶质细胞瘤的转移潜力和恶性转化进一步有助于预后不良。最近的数据表明，BRAF在LGA的约23％和60％的Xanthostolocytomas中被突变。我们已经在小鼠中建立了两种唯一的儿童LGA模型作为直接患者 - 异种移植物。这些肿瘤保留了原始患者肿瘤的表达谱和基因组改变的特征，因此呈现出独特的模型，以发展替代性，令人衰弱的治疗疗法。 BT-40异种移植物是突变BRAF（V600E）的杂合子，而BT-35异种移植物具有野生型BRAF。 BT-40肿瘤对MEK抑制剂AZD6244非常敏感，而BT-35肿瘤无反应，这是野生型BRAF的其他儿童肿瘤异种移植物的典型特征。对AZD6244的抗性的特征是MEK依赖性基因特征，增强的IL-6转录和分泌以及STAT3信号传导的激活。随着肿瘤在未处理的小鼠中转移至药物敏感性，对AZD6244的耐药性是不稳定的，并且与IL-6和STAT3激活降低相关。此外，由于MEK抑制了两个BRAF（V600E）突变体星形胶质细胞系本质上抗AZD6244的抗性。 STAT3激活在AIM 1中的作用将在AIM 1中研究。对于BT-40肿瘤对AZD6244的敏感性的特征是完全抑制TORC1信号传导，表明突变体BRAF控制PI3K/TORC1信号轴。 AKT和STAT3信号在TORC1的MEK调节中的作用，以及对MEK和STAT3的同时抑制在AIM 2中研究了对AZD6244的抗性或对AZD6244的反向抗性。我们计划利用Mutant Braf的控制在Torc1上通过治疗方法来利用Mutant Braf的控制。在BT-40异种移植物中，MEK抑制作用导致DNA修复蛋白fancd2（Torc1下游）的快速和完全丧失，因此有可能选择性地将肿瘤细胞敏化对顺铂，依托泊苷和电离辐射。此外，我们将测试以下概念：顺铂O依托泊苷与AZD6244的组合将防止AZD6244抗药性细胞的出现，因为需要突变体BRAF来维持与接触顺铂或依托泊肽的细胞中与生存相关的AKT信号传导。我们将建立突变BRAF LGA的其他模型，并确定BT-40异种移植物的结果通常适用。这些数据将构成与当前的治疗方法相比，与当前的治疗方法相比，新型非生物毒性和更常规的疗法的快速转化是基础，对于复发性或外科手术不可切除的LGA的儿童而言。