Translational Development of Replication-Competent Retrovirus Vectors

描述(申请人提供)：多形性胶质母细胞瘤(GBM)是成人最常见的原发脑肿瘤，尽管进行了积极的手术、放疗和化疗，但预后仅为12-15个月。缺乏有效的治疗选择使这种疾病成为基因治疗等新策略的目标。然而，基因治疗的唯一重大第三阶段临床试验，涉及在GBM患者中使用传统的复制缺陷逆转录病毒载体，导致令人失望的低转导水平和治疗不足，仅为0.02%。因此，标准复制缺陷逆转录病毒载体无法在体内实现对肿瘤的有效转导是胶质瘤基因治疗的主要障碍。使用具有复制能力的载体进行基因转移将更加有效，因为每个成功转导的肿瘤细胞本身都会成为产生病毒的细胞，即使在最初给药后也能维持进一步的转导事件。我们先前已经证明，直接瘤内注射基于小鼠白血病病毒(MLV)的复制能力强的逆转录病毒(RCR)载体制剂可以在胶质瘤中实现非常有效的自杀基因转移，转导严格限制在活跃分裂的肿瘤细胞而没有明显扩散到肿瘤外的证据，并导致前药给药显著延长生存期，没有检测到全身副作用。在与加州大学洛杉矶分校、南加州大学和加州大学旧金山分校的神经外科小组以及国家基因载体实验室(NGVL)的合作下，我们提议开发和实施临床级RCR载体生产(Aim 1)，通过在啮齿动物脑胶质瘤模型和更大的犬模型(Aim‘2)中进行疗效确证测试来验证这些临床级RCR载体的有效性，根据FDA指南的要求优化监测方法，并制定临床试验方案(Aim 3)。因此，我们建议通过U01机制进行这些必要的临床前转化研究，最终目标是提交IND并获得FDA的批准，以启动临床试验。

DESCRIPTION (provided by applicant): Glioblastoma multiforme (GBM), the most common primary brain tumor in adults, is associated with a dismal prognosis of only 12-15 months despite aggressive surgery, radiation, and chemotherapy. The lack of effective treatment options has made this disease a target for new strategies such as gene therapy. However, the only major Phase III clinical trial of gene therapy, involving the use of conventional replication-defective retrovirus vectors in GBM patients, resulted in disappointingly low and therapeutically inadequate transduction levels on the order of only 0.02%. The inability of standard replication-defective retroviral vectors to achieve effective transduction of tumors in vivo is therefore a major obstacle to gene therapy for gliomas. The use of replication-competent vectors for gene transfer would be more efficient, as each tumor cell that is successfully transduced would itself become a virus-producing cell, sustaining further transduction events even after initial administration. We have previously demonstrated that direct intratumoral injection of murine leukemia virus (MLV)-based replication-competent retrovirus (RCR) vector preparations can achieve tremendously efficient suicide gene transfer in gliomas, with transduction stringently restricted to the actively dividing tumor cells without evidence of significant spread to extratumoral sites, and resulting in significantly prolonged survival upon prodrug administration, without detectable systemic side effects. In collaboration with neurosurgery groups at UCLA, USC, and UCSF, and the National Gene Vector Laboratory (NGVL), here we propose to develop and implement clinical grade RCR vector production (Aim 1), to validate these clinical grade vectors by confirmatory testing of therapeutic efficacy in rodent intracranial glioma models, and in larger canine models (Aim'2), to optimize monitoring methodologies as mandated by FDA guidelines, and to develop clinical trial protocols (Aim 3). Hence, we propose to perform these necessary preclinical translational studies through this U01 mechanism, with the final goal of filing an IND and obtaining approval from the FDA to initiate clinical trials.