Oncolytic VSV for Hepatocellular Carcinoma

描述（由申请人提供）：肝细胞癌（HCC）是世界上第三大癌症死亡原因，未经治疗的患者中位生存时间仅为7.8个月。靶向肿瘤的连续复制病毒正在被开发为一类新型的用于癌症治疗的溶瘤剂。水泡性口炎病毒（VSV）是一种细胞质RNA病毒，由于其减弱的抗病毒应答，对肿瘤细胞中的复制具有固有特异性。我们在培养的大鼠和人HCC细胞中证明了强大的VSV复制和细胞病变效应，而正常大鼠和人肝细胞是难治性的。我们已经构建了一个融合rVSV载体，并表明通过肝动脉输注，它到达并复制在大的多灶性肝癌病灶在同基因和免疫功能正常的大鼠，导致大规模的肿瘤破坏和生存期延长，而没有肝脏病理。虽然令人鼓舞，但肿瘤内病毒复制仅在一天后达到峰值，并且仅在一小部分治疗动物中实现了长期存活。肿瘤内病毒滴度的对数下降超过一天与NK细胞、中性粒细胞和巨噬细胞在肿瘤部位的浸润和积聚同时发生，并且在病毒治疗前通过抗体介导的这些炎性细胞的消耗显著增强了溶瘤作用。我们假设，VSV的溶瘤效力可以通过载体介导的来自抑制NK细胞活性和炎性细胞趋化性的异源病毒的基因表达而显著提高，使得肿瘤内病毒复制将从宿主建立中和抗体应答所需的一天延长至几天，这将导致稳健的溶瘤和显著延长的存活。此外，在高于最大耐受剂量的病毒剂量下，一些给药大鼠表现出神经病理学体征，表现为肢体瘫痪，并且在脑和脊髓的神经元中检测到病毒。我们假设，神经元病毒的复制和传播可以通过分子工程的VSV基因组，使相关的病毒mRNA的翻译将被抑制的指导下的内部核糖体进入位点的异源病毒，在神经元中是非功能性的，但在肝癌细胞中是活跃的。拟议研究的成功进行可能会导致未来开发有效和神经减毒的rVSV载体作为有效和安全的溶瘤药物，用于治疗晚期HCC和其他癌症患者。

DESCRIPTION (provided by applicant): Hepatocellular Carcinoma (HCC) is the third leading cause of cancer deaths in the world with a median survival time of only 7.8 months in untreated patients. Conditionally replicating viruses targeted to tumors are being developed as a novel class of oncolytic agents for cancer treatment. Vesicular Stomatitis Virus (VSV) is a cytoplasmic RNA virus with inherent specificity for replication in tumor cells due to their attenuated anti- viral responses. We demonstrated robust VSV replication and cytopathic effects in cultured rat and human HCC cells, while normal rat and human hepatocytes were refractory. We have constructed a fusogenic rVSV vector and showed that through hepatic artery infusion, it reached and replicated in large multi-focal HCC lesions in the livers of syngeneic and immune-competent rats that led to massive tumor destruction and survival prolongation, and without liver pathology. While encouraging, intratumoral virus replication peaked after only one day and long-term survival was achieved in only a minor fraction of the treated animals. The logarithmic decline in intratumoral virus titers beyond one-day was co-incidental with the infiltration and accumulation of NK cells, neutrophils and macrophages at the tumor sites, and oncolysis was substantially enhanced by antibody-mediated depletion of these inflammatory cells prior to virus treatment. We hypothesize that the oncolytic potency VSV can be significantly elevated by vector-mediated expression of genes from heterologous viruses that suppress NK cell activity and chemotaxis of inflammatory cells, so that intratumoral virus replication will be extended from one to several days needed by the host to mount a neutralizing antibody response, which will lead to robust oncolysis and substantially prolonged survival. Additionally, at virus dosages above the maximum tolerated dose some treated rats exhibited signs of neuro-pathology manifested by limb paralysis, and virus was detected in neurons in the brain and spinal cord. We hypothesize that neuronal virus replication and spread can be inhibited by molecularly engineering the VSV genome so that the translation of pertinent viral mRNAs will be under the direction of internal ribosome entry sites of heterologous viruses that are non-functional in neurons but active in HCC cells. The successful conduct of the proposed research may lead to the future development of potent and neuro-attenuated rVSV vectors as effective and safe oncolytic agents to treat patients with advanced HCC and other cancers.