Glioma Therapy Using Targeted Oncolytic HSV Vectors

描述（由申请人提供）：多形性胶质母细胞瘤（GBM）是一种毁灭性疾病，尽管尽了最大努力使用标准疗法（包括手术、放疗和化疗），但几乎总是导致患者死亡。需要新的治疗干预措施，可与标准医疗实践结合使用。在这些治疗方法中，基因治疗可能有望治疗GBM，但有效的基因递送仍然存在障碍。高度减毒的复制型HSV-1载体提供了一个强大的机会，提供有效的基因递送，除了自然裂解功能（溶瘤）和早期人体试验支持这种方法的安全性。在该提议中，概述了实验以探索通过改善肿瘤块内的载体分布来增强HSV溶瘤载体效力的方法，测试另外的突变载体骨架，其性能可以通过增强的和更特异的内-肿瘤复制和通过使用额外的转基因，其可以更有效地破坏肿瘤块，包括局部浸润肿瘤细胞进入正常的脑组织在整个研究过程中，将结合放射外科手术评价载体性能和肿瘤杀伤。我们将使用G207的性能作为基准来比较任何矢量改进。在四个相关的具体目标中，我们将：（i）利用胶原酶来增强肿瘤内载体分布，如通过先进的活体显微镜观察到的;（ii）检查HSV基因组中的新的遗传改变，以寻找更具活性的突变体溶瘤载体，其具有与目前用于早期患者研究的载体相同或更好的安全性特征（iii）开发重靶向策略，以通过识别肿瘤细胞受体来实现肿瘤特异性HSV感染;和（iv）将新的抗肿瘤转基因引入载体骨架，包括（a）嘌呤核苷磷酸化酶（PNP）与6-甲基嘌呤（MeP）处理的组合，（B）氯毒素（CltX），一种抑制肿瘤细胞迁移并可能诱导肿瘤细胞凋亡的肽;（c）肿瘤坏死因子（TNF），其作用是使肿瘤细胞和肿瘤血管系统对放射外科方法敏感。这些研究的结果旨在发现新的载体、更有效的转基因和递送策略，这些载体、转基因和递送策略一起可以提供基因治疗作为一种有效的方法，至少延长复发性GBM患者的生存期。

DESCRIPTION (provided by applicant): Glioblastoma multiforme (GBM) is a devastating disease that almost invariably leads to patient death despite best efforts using standard therapies that include surgery, radiation and chemotherapy. New therapeutic interventions are needed which may be used in combination with standard medical practice. Among these treatments, gene therapy potentially holds promise for treatment of GBM however impediments to effective gene delivery remain. Highly attenuated replication competent HSV-1 vectors provide a powerful opportunity to provide effective gene delivery in addition to the natural lytic features (oncolysis) and early phase human trials support the safety of this approach. In this proposal, experiments are outlined to explore methods to enhance the potency of HSV oncolytic vectors through improved vector distribution within the tumor mass, the testing of additional mutant vector backbones whose performance may be improved by enhanced and more specific intra-tumoral replication and through the use of additional transgenes that may be more effective in destruction of the tumor mass including locally infiltrating tumor cells into normal brain tissue. Throughout this investigation vector performance and tumor killing will be evaluated in combination with radiosurgery. We will use the performance of G207 as a benchmark with which to compare any vector improvements. In four related specific aims we will: (i) Exploit the use of collagenases to enhance intra-tumoral vector distribution as visualized by advanced vital microscopy; (ii) Examine new genetic alterations in the HSV genome in a search for more active mutant oncolytic vectors that have the same or better safety profiles as vectors currently used in early phase patient studies (e.g. G207); (iii) Develop retargeting strategies to enable tumor-specific HSV infection through recognition of tumor-cell receptors; and (iv) Introduce novel anti-tumor transgenes into the vector backbone that include (a) purine nucleoside phosphorylase (PNP) in combination with 6-methylpurine (MeP) treatment, (b) chlorotoxin (CltX), a peptide that inhibits tumor cell migration and may induce tumor cell apoptosis (c) tumor necrosis factor (TNF() that acts to sensitize tumor cells and the tumor vasculature to radiosurgical methods. The outcome of these studies are intended to discover new vectors, more effective transgenes and delivery strategies which together may provide gene therapy as an effective approach to at least prolong the survival of patients with recurrent GBM over currently available treatment methods.