Thermally Targeted Delivery of c-Myc Inhibitory Polypeptides to Malignant Gliomas

描述（由申请人提供）：恶性胶质瘤是胶质瘤中最大的一组，由于其高增殖潜力、颅内扩散的强烈倾向以及常规治疗的严重不良反应，其预后不良。虽然手术切除联合辅助化疗和/或放疗用于治疗恶性胶质瘤，但肿瘤对放疗或化疗的固有抗性以及全身给药化疗药物的毒性通常会阻碍成功结局。因此，由于目前神经胶质瘤治疗方法的局限性，我们的长期目标是开发一种针对局部肿瘤的靶向治疗方法，提高治疗的特异性和有效性，并降低正常组织中的细胞毒性。我们已经开发了一种热响应多肽（CPP-ELP-H1），抑制c-Myc转录活性和恶性胶质瘤细胞增殖。所提出的研究的目的是证明在体内全身给药后，这些基因工程多肽可以通过施加局部热疗靶向脑肿瘤部位并抑制肿瘤生长。热响应多肽的氨基酸序列基于弹性蛋白样（ELP）生物聚合物，其在低于生理温度（37 ℃）的水溶液中可溶，但当温度升高到41 ℃以上时聚集。将细胞穿透肽（CPP）、Bactenecin（Bac）或达特与ELP缀合以增强多肽穿过血脑屏障的递送并促进细胞进入。向CPP-ELP中加入衍生自c-Myc的螺旋-环-螺旋结构域的螺旋1（H1）的肽，其抑制c-Myc的转录激活并因此抑制癌细胞增殖。我们的假设是静脉内递送的热响应c-Myc抑制多肽可能在生理条件下（37 ℃）被清除。然而，它们将在大鼠脑中生长的胶质瘤中积累，其中将施加外部诱导的局部加热（40-42 ° C）。积累的多肽将阻断c-Myc活性，从而抑制癌细胞的增殖。为了解决这一假设，将解决以下具体目标：（1）测量CPP-ELP-H1在正常和肿瘤组织中的血浆动力学和体内分布，以及（2）通过重复施用该药剂并结合和不结合局部热疗，评价CPP-ELP-H1在治疗大鼠肿瘤性脑肿瘤中的治疗功效。拟议研究的成功完成将提供ELP可以以热靶向方式提供治疗分子并减小脑肿瘤大小的第一个证据，这项工作将获得必要的毒性，药代动力学，生物分布和有效性数据，以推动这项技术朝着人类治疗的最终目标发展。因此，拟议的研究可能会产生重大影响，将这项技术引入临床试验，并可能为治疗和管理脑肿瘤提供强大的技术。 公共卫生相关性：胶质母细胞瘤是最常见和最具侵袭性的原发性脑肿瘤。尽管在包括手术、放疗和化疗的联合治疗方案方面取得了进展，但由于治疗剂的血脑屏障渗透性差、对化疗剂的抗性和正常组织中的非特异性细胞毒性，胶质母细胞瘤诊断的预后仍然暗淡。由于目前胶质母细胞瘤治疗方法的局限性，本研究的目的是开发一种热响应性治疗多肽，其可以通过局部热疗靶向脑肿瘤部位并抑制其生长。

DESCRIPTION (provided by applicant): Malignant gliomas represent the largest group of glial tumors, and they have a poor prognosis because of their high proliferation potential, strong tendency for intracranial dissemination, and the severe adverse effects of conventional therapies. Although surgical resection with adjuvant chemotherapy and/or radiotherapy is used to treat malignant gliomas, inherent tumor resistance to radiation or chemotherapy and toxicity from systemic administration of antineoplastic agents often hinders a successful outcome. Therefore, motivated by the limitations of current therapeutic approaches for gliomas, our long term goal is to develop a targeted therapeutic approach for localized tumors that increases the specificity and efficacy of the therapy and reduces the cytotoxicity in normal tissues. We have developed a thermally responsive polypeptide (CPP-ELP-H1) that inhibits c-Myc transcriptional activity and malignant glioma cell proliferation. The objective of the proposed research is to demonstrate that after systemic administration in vivo, these genetically engineered polypeptides can be targeted to the brain tumor site by applying local hyperthermia and inhibit tumor growth. The amino acid sequence of the thermally responsive polypeptides is based on the elastin-like (ELP) biopolymer, which is soluble in aqueous solution below physiological temperature (37 0C), but aggregates when the temperature is raised above 41 0C. A cell-penetrating peptide (CPP), Bactenecin (Bac) or Tat, is conjugated to the ELP to enhance delivery of the polypeptide across the blood brain barrier and to facilitate cell entry. To the CPP-ELP is added a peptide derived from helix 1 (H1) of the helix-loop-helix domain of c-Myc, which inhibits transcriptional activation by c-Myc and consequently inhibits cancer cell proliferation. Our hypothesis is that intravenously delivered thermally responsive c-Myc inhibitory polypeptides are likely to be cleared under physiological conditions (37 0C). However, they will accumulate in gliomas grown in rat brains, where externally induced local heat (40-42 0C) will be applied. The accumulated polypeptides will block c-Myc activity and consequently inhibit proliferation of the cancer cells. In order to address this hypothesis, the following specific aims will be addressed: (1) measure the plasma kinetics and in vivo distribution of CPP-ELP-H1 in normal and neoplastic tissue and (2) evaluate the therapeutic efficacy of CPP-ELP-H1 in the treatment of neoplastic brain tumors in rats through repeated administration of the agent coupled with and without local hyperthermia. Successful completion of the proposed study will provide the first evidence that ELP can deliver a therapeutic molecule and reduce brain tumor size in a thermally targeted manner, and this work will obtain the necessary toxicity, pharmacokinetic, biodistribution, and efficacy data necessary to advance this technology toward the ultimate goal of human therapeutics. Therefore, proposed research may have a significant impact, leading this technology into clinical trials, and it may provide a powerful technology to treat and manage brain tumors. PUBLIC HEALTH RELEVANCE: Glioblastoma is the most common and most aggressive of the primary brain tumors. Despite advances in combined treatment regimens including surgery, radio- and chemotherapy, the prognosis of a glioblastoma diagnosis is still bleak due to poor blood- brain barrier penetration of therapeutics, resistance to chemotherapeutic agents and nonspecific cytotoxicity in normal tissues. Motivated by the limitations of current therapeutic approaches for treatment of glioblastoma, the objective of the proposed research is to develop a thermally responsive therapeutic polypeptide which can be targeted to the brain tumor site by applying local hyperthermia and inhibit its growth.