Hamster Model for Oncolytic Adenovirus Vectors

描述（由申请人提供）：已评价了腺病毒载体在治疗癌症中的功效。由于癌症是美国的第二大死亡原因，并且目前的治疗方法并不总是足够的，因此需要新的癌症疗法。作为病毒生命周期的一部分，具有复制能力的溶瘤腺病毒载体已被设计用于杀死癌细胞。我们实验室已经开发了一系列独特的溶瘤腺病毒载体的基础上过表达的腺病毒编码的蛋白命名为ADP。ADP在感染后期促进病毒从细胞中释放，并有助于腺病毒的细胞间传播。我们的假设是ADP的高水平表达将增加载体在肿瘤中从细胞到细胞扩散的能力，从而破坏肿瘤。我们的载体可有效破坏细胞培养中的人类癌细胞，并抑制免疫缺陷（裸）小鼠中的肿瘤生长。人异种移植物-裸鼠模型通常用于评价溶瘤腺病毒载体，因为教条认为人腺病毒不在动物中复制。允许或至少半允许人腺病毒复制并具有完整免疫系统的更现实的动物模型对于溶瘤腺病毒癌症基因治疗领域具有重要价值。我们已经确定叙利亚仓鼠作为溶瘤腺病毒载体的动物模型，具有良好的效果。我们发现，腺病毒能够感染，复制，并在这种动物的癌细胞系中从细胞传播到细胞。腺病毒在肺、肝和其他器官中复制。我们的溶瘤腺病毒载体抑制三种不同仓鼠肿瘤的生长并在这些肿瘤内复制。我们的载体以及野生型腺病毒和复制缺陷型腺病毒对照的毒性和药代动力学生物分布已经在静脉内施用这些病毒后确定。我们建议进一步发展这种溶瘤腺病毒肿瘤基因治疗的动物模型。在具体目标1中，我们将研究宿主、载体和肿瘤细胞之间的相互作用。我们将研究载体在肿瘤中的复制和扩散，确定限制载体功效的因素，如肿瘤结构，载体抗性或免疫力，并研究免疫系统在抑制肿瘤生长中的作用。在具体目标2中，我们将确定放疗和化疗对Ad载体在细胞培养物和动物模型中的功效的影响。在具体目标3中，我们将研究复制选择性载体在该模型中的功效，并尝试在仓鼠中开发原位肺转移和胰腺癌模型。这些研究应该有助于推进我们的载体和可能的溶瘤腺病毒载体从其他研究小组走向临床试验。虽然在本申请中没有特别提出，但这些研究也应该提供关于腺病毒发病机制的新信息。

DESCRIPTION (provided by applicant): Adenovirus vectors have been evaluated for their efficacy in treating cancer. As cancer is the second leading cause of death in the U.S. and current therapeutics are not always sufficient, new cancer therapies are desired. Replication-competent oncolytic adenovirus vectors have been designed to kill cancer cells as part of the virus life cycle. Our laboratory has developed a series of unique oncolytic adenovirus vectors based on the overexpression of an adenovirus-coded protein named ADP. ADP promotes virus release from the cell late in infection and aids in the cell-to-cell spread of adenovirus. Our hypothesis is that high level of expression of ADP will increase the ability of the vector to spread from cell-to-cell in the tumor and thereby destroy the tumor. Our vectors are efficacious in destroying human cancer cells in cell culture and suppressing the growth of tumors in immunodeficient (nude) mice. The human xenograft-nude mouse model is commonly used to evaluate oncolytic adenovirus vectors because the dogma holds that human adenoviruses do not replicate in animals. A more realistic animal model that is permissive or at least semi-permissive for human adenovirus replication and that has an intact immune system would be of great value to the field of oncolytic adenovirus cancer gene therapy. We have identified the Syrian hamster as an animal model for oncolytic adenovirus vectors with promising results. We found that adenovirus is able to infect, replicate, and spread from cell-to-cell in cancer cell lines of this animal. Adenovirus replicates in the lungs, liver, and other organs. Our oncolytic adenovirus vector suppresses the growth of three different hamster tumors and replicates within these tumors. The toxicity and pharmacokinetic biodistribution of our vector as well as wild-type adenovirus and replication-defective adenovirus controls have been determined following intravenous administration of these viruses. We propose to further develop this animal model for oncolytic adenovirus cancer gene therapy. In Specific Aim 1 we will investigate the interaction between the host, vector, and tumor cells. We will examine vector replication and spreading in tumors, identify factors such as tumor architecture, vector resistance, or immunity that limit the efficacy of vectors, and study the role of the immune system in suppressing tumor growth. In Specific Aim 2 we will determine the effect of radiation and chemotherapy on the efficacy of Ad vectors, both in cell culture and in the animal model. In Specific Aim 3 we will investigate the efficacy of replication-selective vectors in this model and attempt to develop orthotopic lung metastasis and pancreatic cancer models in the hamster. These studies should help advance our vectors and possibly oncolytic adenovirus vectors from other research groups toward clinical trials. Although not proposed specifically in this application, these studies should also provide novel information on adenovirus pathogenesis.