Hamster Model for Oncolytic Adenovirus Vectors

描述(由申请人提供)：腺病毒载体已被评估其治疗癌症的效果。由于癌症是美国第二大死亡原因，而目前的治疗方法并不总是足够的，因此需要新的癌症治疗方法。具有复制能力的溶瘤腺病毒载体被设计成作为病毒生命周期的一部分来杀死癌细胞。我们实验室基于腺病毒编码的ADP蛋白的过度表达，开发了一系列独特的溶瘤腺病毒载体。ADP促进病毒在感染后期从细胞中释放，并助助腺病毒在细胞间传播。我们的假设是，ADP的高水平表达将增加载体在肿瘤细胞之间传播的能力，从而摧毁肿瘤。我们的载体有效地摧毁了细胞培养中的人类癌细胞，并抑制了免疫缺陷(裸)小鼠的肿瘤生长。人类异种移植-裸鼠模型通常被用来评价溶瘤腺病毒载体，因为这个教条认为人腺病毒不能在动物体内复制。一个对人腺病毒复制是允许的或至少是半允许的，并且具有完整的免疫系统的更真实的动物模型将对溶瘤腺病毒癌症基因治疗领域具有重要的价值。我们已经将叙利亚仓鼠确定为溶瘤腺病毒载体的动物模型，结果令人振奋。我们发现，腺病毒能够在这种动物的癌细胞系中感染、复制和在细胞之间传播。腺病毒在肺、肝和其他器官中复制。我们的溶瘤腺病毒载体可以抑制三种不同仓鼠肿瘤的生长，并在这些肿瘤中复制。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注射这些病毒后被确定。我们建议进一步发展这种溶瘤腺病毒癌基因治疗的动物模型。在特定目标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，识别限制载体疗效的因素，如肿瘤结构、载体抵抗或免疫，并研究免疫系统在抑制肿瘤生长中的作用。在特定的目标2中，我们将在细胞培养和动物模型中确定放射和化疗对Ad载体效果的影响。在具体目标3中，我们将研究复制选择载体在该模型中的有效性，并尝试在仓鼠体内建立原位肺转移和胰腺癌模型。这些研究应该有助于推动我们的载体，以及可能来自其他研究小组的溶瘤腺病毒载体进行临床试验。虽然在本申请中没有特别提出，但这些研究也应该提供对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.