Retroviral Replicating Vector-mediated Gene Therapy for Ovarian Cancer

卵巢癌是美国妇科恶性肿瘤患者的主要死亡原因， 总体5年存活率为50%。复发通常是局部的，累及腹膜和腹部。 器官，特别是对铂耐药疾病，它对化疗的应答率降低， 需要改进治疗方法。我们开发了一种使用逆转录病毒复制载体(RRV)的新策略 胞嘧啶脱氨酶等前药物激活剂(自杀)基因的高效和肿瘤选择性传递 (CD)，并基于我们的临床前发现，首个人类RRV-CD自杀基因的多中心临床试验 全美各地都开始对复发的高级别胶质瘤进行局部肿瘤部位注射的治疗， 并显示出非常有希望的临床益处、放射学反应和提高存活率的迹象，以及 目前正在进行第二阶段B/第三阶段的注册试验。此外，根据我们最近的临床前数据显示 即使是全身静脉注射，RRV也高度受限于活跃地分裂肿瘤细胞，而不是 扩散到免疫活性宿主的正常组织，并导致使用前药延长存活时间 给药没有全身副作用，FDA最近批准了一项新的静脉注射临床试验 房车。现在已经有了临床先例，现在是时候考虑系统地或局部地应用了 RRV也用于全身恶性肿瘤，如卵巢癌。因此，我们在此建议 首次临床前研究评估轮状病毒介导的自杀基因治疗的可行性、安全性和有效性 治疗-难治性复发性卵巢癌。在细胞水平上，我们将进行基因表达谱分析 评估原代患者来源的卵巢癌细胞是否表达候选抗病毒限制因子 这可能会影响这一策略的未来临床应用，并经验性地测试RRV复制和 利用RRV，卵巢癌细胞中自杀基因的活性与基因表达谱结果相关 用不同的信封进行假定型，以实现共同感染(目标1)。转移性卵巢癌将需要 通过静脉或腹腔给药广泛传播媒介，将对这两种途径进行评估 为了在卵巢癌腹膜癌模型中的转导效率和生物分布/安全性，使用 免疫缺陷小鼠中的人类异种移植和免疫活性小鼠中的同基因模型(目标2)。下一首, 我们将评估临床RRV-CD(TOCA511)载体和一种新开发的自杀基因治疗 编码细菌硝基还原酶(NTR)的RRV，它在体内产生一种促进免疫原性的烷化剂 单独和联合感染癌细胞(目标3)。作为肿瘤定位的RRV前药转化 破坏免疫抑制的肿瘤间质，同时引起最小的全身骨髓毒性并维持 在免疫系统完好的情况下，我们还将测试亲免疫原性RRV自杀基因联合治疗的疗效 带有遗传免疫检查点抑制。如果目前提出的临床前研究证明是成功的，这些 治疗难治性晚期卵巢癌的方法可能会迅速转化为临床。

Ovarian cancer is the leading cause of death in women with gynecological malignancies in the U.S., with an overall 5-year survival of <50%. Recurrences are often locoregional, involving peritoneum and abdominal organs, and especially for platinum-resistant disease which shows reduced response rates to chemotherapy, improved treatments are needed. We developed a novel strategy using retroviral replicating vectors (RRV) for highly efficient and tumor-selective delivery of prodrug activator (`suicide') genes such as cytosine deaminase (CD), and based on our preclinical findings, first-in-human multi-center clinical trials of RRV-CD suicide gene therapy delivered by local tumor site injection were initiated throughout the U.S. for recurrent high-grade glioma, and have shown highly promising signs of clinical benefit, radiographic responses, and increased survival, and a Phase IIB/III registrational trial is now on-going. Furthermore, based on our recent preclinical data showing that, even with systemic intravenous delivery, RRV is highly restricted to actively dividing tumor cells, without spread to normal tissues in immunocompetent hosts, and results in prolonged survival upon prodrug administration without systemic side effects, FDA recently approved a new clinical trial for intravenous delivery of RRV. Now that there is clinical precedent, it is timely to consider applying systemically or locoregionally administered RRV also to systemic malignancies such as ovarian cancer. Accordingly, here we propose the first preclinical studies to evaluate the feasibility, safety, and efficacy of RRV-mediated suicide gene therapy for treatment-refractory recurrent ovarian cancer. At the cellular level, we will perform gene expression profiling to evaluate whether primary patient-derived ovarian cancer cells express candidate anti-viral restriction factors that might impact future clinical application of this strategy, and empirically test whether RRV replication and suicide gene activity in ovarian cancer cells correlates with gene expression profiling results, using RRV pseudotyped with different envelopes to enable co-infection (Aim 1). Metastatic ovarian cancer will necessitate widespread vector delivery via intravenous or intraperitoneal administration, and both routes will be evaluated for transduction efficiency and biodistribution/safety in ovarian cancer peritoneal carcinomatosis models, using human xenografts in immunodeficient mice and syngeneic models in immunocompetent mice (Aim 2). Next, we will evaluate suicide gene therapy with both the clinical RRV-CD (Toca 511) vector and a newly developed RRV encoding bacterial nitroreductase (NTR), which generates a pro-immunogenic alkylating agent within infected cancer cells, individually and in combination (Aim 3). As tumor-localized prodrug conversion by RRV destroys immunosuppressive tumor stroma, while incurring minimal systemic myelotoxicity and maintaining an intact immune system, we will also test the efficacy of pro-immunogenic RRV suicide gene therapy combined with genetic immune checkpoint inhibition. If the currently proposed preclinical studies prove successful, these approaches could be rapidly translated to the clinic for treatment-refractory advanced ovarian cancer.