Targeted EGFR Antisense Gene Therapy of Brain Cancer

描述(申请人提供)：美国的脑癌发病率惊人地高，包括每年15,000例高度恶性的原发脑癌，多形性胶质母细胞瘤(GBM)，以及每年约150,000例脑转移癌。表皮生长因子受体(EGFR)每年在超过10万例脑癌患者中发挥致癌作用，是正在开发的癌症新疗法的头号靶点。高达50%的脑癌患者表达突变形式的EGFR，这种突变形式通常对阻断野生型EGFR的药物具有耐药性。此外，脑部抗EGFR癌症治疗的成功受到血脑屏障(BBB)的存在的限制，血脑屏障在脑癌早期仍有可能治疗时是完好无损的。没有一种大分子药物(单抗、癌症疫苗、基因疗法)跨越血脑屏障，而98%的小分子癌症治疗药物没有跨越血脑屏障。因此，血脑屏障药物/基因靶向技术的发展是抗击脑癌的关键一步。目前的工作将开发一种新的非病毒、非侵入性脑基因疗法，用于治疗依赖EGFR的基底膜或转移性癌症。新的基因传递技术采用聚乙二醇化免疫脂质体(PILS)，是非侵入性的，只需要每周静脉注射。PIL基因转移技术将与反义机制的力量相结合，开发出能够将野生型或突变型EGFR基因压低90%的脑癌新基因疗法。由于基于RNA的反义药物在体内不稳定，目前的工作将开发新的基于质粒的基因药物，在靶细胞内产生反义RNA，特异性攻击野生型或突变型EGFR mRNA。EGFR反义编码基因药物将与一种充当分子特洛伊木马(MTH)的基因工程重组蛋白一起传递给脑癌。这种MTH运送携带基因药物的PIL穿过体内的膜屏障，将血液与脑癌细胞的细胞核分开。MTH触发受体介导的PIL跨血脑屏障的顺序转运，以及受体介导的PIL内吞进入脑癌细胞。

DESCRIPTION (provided by applicant): The incidence of brain cancer in the U.S. is surprisingly high, and includes 15,000 new cases per year of the highly malignant primary brain cancer, glioblastoma multiforme (GBM), and about 150,000 cases per year of metastatic cancer to brain. The epidermal growth factor receptor (EGFR) plays an oncogenic role in over 100,000 cases of brain cancer per year, and is the number 1 target of new cancer therapeutics in development. Up to 50% of patients with brain cancer express mutant forms of the EGFR, which are generally resistant to drugs that block the wild type EGFR. Moreover, the success of anti-EGFR cancer therapeutics for the brain is limited by the presence of the blood-brain barrier (BBB), which is intact in the early phase of brain cancer, when treatment is still possible. None of the large molecule drugs (monoclonal antibodies, cancer vaccines, gene therapies) cross the BBB, and >98% of small molecule cancer therapeutics do not cross the BBB. Therefore, the development of BBB drug/gene targeting technologies is a crucial step in the war against cancer of the brain. The present work will exploit a new form of non-viral, non-invasive gene therapy of the brain for the treatment of EGFR-dependent GBM or metastatic cancer. The new gene delivery technology employs pegylated immunoliposomes (PILs) and is non-invasive, requiring only weekly intravenous injections. The PIL gene transfer technology will be combined with the power of antisense mechanisms to develop new gene therapies of brain cancer that are capable of >90% knockdown of either the wild type or mutant EGFR. Since RNA-based forms of antisense drugs are unstable in vivo, the present work will develop new plasmid based gene medicines that produce antisense RNA within the target cancer cell that specifically attack either the wild type or mutant EGFR mRNA. The EGFR antisense encoding gene medicine will be delivered to brain cancer with a genetically engineered recombinant protein that acts as a molecular Trojan horse (MTH). This MTH ferries the PIL carrying the gene medicine across the membrane barriers in the body that separate the blood from the nucleus of the brain cancer cell. The MTH triggers the sequential receptor-mediated transcytosis of the PIL across the BBB, and the receptor-mediated endocytosis of the PIL into the brain cancer cell.