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）是一种毁灭性的疾病，尽管使用了包括手术、放疗和化疗在内的标准治疗方法，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，基因疗法有望治疗GBM，但有效基因传递的障碍仍然存在。高度减毒的复制能力强的HSV-1载体除了具有天然的裂解特性（溶瘤）外，还为提供有效的基因传递提供了强有力的机会，并且早期人体试验支持该方法的安全性。在本提案中，实验概述了探索增强HSV溶瘤载体效力的方法，通过改善载体在肿瘤块内的分布，测试额外的突变载体骨干，其性能可能通过增强和更特异性的肿瘤内复制来改善，并通过使用额外的转基因来更有效地破坏肿瘤块，包括局部浸润肿瘤细胞进入正常脑组织。在整个研究过程中，将结合放射手术评估载体的表现和肿瘤杀伤。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)利用胶原酶来增强先进生命显微镜可视化的肿瘤内载体分布；（ii）检查HSV基因组中的新遗传改变，以寻找与目前在早期患者研究中使用的载体（例如G207）具有相同或更好安全性的更活跃的突变溶瘤载体；（iii）制定重靶向策略，通过识别肿瘤细胞受体实现肿瘤特异性HSV感染；（iv）在载体主干中引入新的抗肿瘤转基因，包括(a)嘌呤核苷磷酸化酶（PNP）联合6-甲基嘌呤（MeP）治疗，(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，这些共同可能提供基因治疗作为一种有效的方法，至少可以延长复发性GBM患者的生存期，而不是目前可用的治疗方法。

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.