Retroviral Replicating Vector-mediated Gene Therapy for Ovarian Cancer

在美国，卵巢癌是妇科恶性肿瘤妇女的主要死亡原因，与 总体5年生存率<50%。复发性常为局部性，累及腹膜和腹部 器官，特别是对化疗反应率降低的铂耐药疾病， 需要改进的治疗。我们开发了一种新的策略，使用逆转录病毒复制载体（RRV）， 前药激活剂（“自杀”）基因如胞嘧啶脱氨酶高效和肿瘤选择性递送 (CD)根据我们的临床前研究结果，RRV-CD自杀基因的首次人体多中心临床试验 通过局部肿瘤部位注射递送的治疗在整个美国开始用于复发性高级别神经胶质瘤， 并显示出非常有希望的临床获益、放射学反应和生存率增加的迹象， a目前正在进行IIB/III期注册试验。此外，根据我们最近的临床前数据显示， 即使使用全身静脉内递送，RRV也高度限制于活跃分裂的肿瘤细胞， 在免疫活性宿主中扩散到正常组织，并导致前药后存活延长 FDA最近批准了一项新的静脉给药临床试验， 的RRV。既然有了临床先例，现在是考虑全身或局部应用的时候了 RRV也可用于全身性恶性肿瘤，如卵巢癌。因此，我们在此提出 第一个临床前研究，以评估RRV介导的自杀基因治疗的可行性，安全性和有效性， 难治性复发性卵巢癌在细胞水平，我们将进行基因表达谱分析， 评估原发性患者来源的卵巢癌细胞是否表达候选抗病毒限制因子 这可能会影响该策略的未来临床应用，并经验性地测试RRV复制和 卵巢癌细胞中自杀基因活性与RRV基因表达谱结果相关 用不同的信封进行假型化，以实现共同感染（目标1）。转移性卵巢癌需要 通过静脉内或腹膜内给药进行广泛的载体递送，并将对两种途径进行评价 对于卵巢癌腹膜癌病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异种移植物和免疫活性小鼠中的同基因模型（Aim 2）。接下来， 我们将评估使用临床RRV-CD（Toca 511）载体和新开发的 RRV编码细菌硝基还原酶（NTR），其在RRV内产生促免疫原性烷化剂。 感染的癌细胞，单独和组合（目的3）。通过RRV的肿瘤局部前药转化 破坏免疫抑制性肿瘤基质，同时引起最小的全身性骨髓毒性并维持免疫抑制性肿瘤基质。 完整的免疫系统，我们还将测试前免疫原性RRV自杀基因治疗联合 基因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， 该方法可以迅速转化为临床治疗难治性晚期卵巢癌。

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.