Virotherapy for pancreatic cancer with wildtype and armed Myxoma viruses

描述（由申请人提供）：本申请的目的是在临床前动物模型中研究MYXV作为胰腺癌潜在溶瘤病毒治疗剂的使用。该建议的重点是MYXV，并以我们以前发表的报告和支持性初步研究为基础。MYXV是一种兔特异性痘病毒，在体内对多种人类癌症模型具有溶瘤活性，包括脑肿瘤、黑色素瘤和横纹肌样肿瘤。此外，我们最近报道了MYXV能够在体外感染和杀死胰腺癌细胞。我们在提案主体中提供的初步研究表明，MYXV在免疫缺陷和免疫正常的胰腺癌动物模型中都表现出强大的溶瘤活性。基于这些结果，我们试图评估MYXV与当前化疗方案（特别是吉西他滨）联合治疗胰腺癌的疗效。我们假设MYXV在体内对胰腺癌具有强大的溶瘤活性，并且可能联合和/或改造以增强当前的化疗治疗。野生型MYXV和携带化疗致敏基因的重组MYXV将被评估为单药治疗和与目前批准用于治疗胰腺癌的化疗药物联合治疗。为了这项资助的目的，我们提出：1)评估野生型MYXV溶瘤剂在小鼠胰腺癌模型中的疗效。将评估MYXV: a)与标准化疗相比，作为单药治疗，b)与吉西他滨和/或厄洛替尼联合，以及c)化疗耐药肿瘤的二线治疗。这些实验涉及使用最常见的胰腺癌一线化疗，因此将在临床相关情况下评估MYXV。将建立免疫缺陷和免疫正常的胰腺癌小鼠模型，并通过腹腔注射途径局部给药。肿瘤负担和生存曲线将在存在或不存在吉西他滨和吉西他滨难治性肿瘤的治疗组之间进行比较，以确定上述三种方案下的MYXV病毒治疗是否能通过肿瘤负担和生存来提高治疗效益。2)产生带有化疗致敏基因的重组MYXV，增强吉西他滨化疗。将设计表达脱氧胞苷激酶（CDK）或人平衡核苷转运蛋白1（hnt -1）的重组“武装”myxv。这些病毒将在体内进行表征，以确定转基因的表达是否增强了上述特异性目的1中描述的两种模型中基于吉西他滨的胰腺癌细胞的肿瘤溶解。将比较武装MYXV和野生型MYXV治疗组的肿瘤负荷和生存曲线，以确定使用武装MYXV是否通过增强吉西他滨为基础的体内化疗而比野生型MYXV提供治疗优势。该提案将是第一个评估MYXV在胰腺癌临床前动物模型中作为单药治疗和与化疗药物联合治疗的溶瘤潜力的研究，以及能够使细胞对吉西他滨化疗敏感的武装MYXV的特性。因此，如果成功，这些试点实验将确定MYXV是一种有效的溶瘤病毒，可以进一步开发为一种新的、安全的治疗胰腺癌的病毒疗法。特别是，如果结果像我们预期的那样积极，并且考虑到MYXV的优异安全性，我们将在拟议的研究完成后继续生产临床级MYXV库存并提交新药研究申请（IND）。

DESCRIPTION (provided by applicant): The objective of this proposal is to investigate the use of MYXV as potential oncolytic virotherapy agent against pancreatic cancer in preclinical animal models. The proposal focuses on MYXV, and is based on our previously published reports and supporting preliminary studies. MYXV is a rabbit-specific poxvirus with oncolytic activity against many types of human cancer models in vivo, including brain tumors, melanoma and rhabdoid tumors. In addition, we reported recently that MYXV is able to infect and kill pancreatic cancer cells in vitro. Our preliminary studies provided in the main body of the proposal show that MYXV exhibits potent oncolytic activity in both immunodeficient and immunocompetent animal models of pancreatic cancer. Based on these results, we seek to evaluate MYXV in combination with current chemotherapy regimens, especially gemcitabine, for pancreatic cancer. We hypothesize that MYXV will have potent oncolytic activity against pancreatic cancer in vivo and may be combined and/or engineered to enhance current chemotherapy treatments. Wildtype MYXV and recombinant MYXV "armed" with chemosensitizing gene(s) will be evaluated as single agent therapies and in combination with current chemotherapy drugs approved for the treatment of pancreatic cancer. For the purposes of this grant, we propose to: 1) Evaluate the efficacy of wildtype MYXV oncolysis in murine models of pancreatic carcinoma. MYXV will be evaluated: a) as a single agent therapy compared to standard chemotherapies, b) in combination with gemcitabine and/or erlotinib, and as c) second line treatment therapy for chemotherapy resistant tumors. These experiments involve the use of the most common first line chemotherapies for pancreatic cancer and will therefore evaluate MYXV in the context of a clinically relevant scenario. Immunodeficient and immunocompetent murine models of pancreatic cancer will be established intraperitoneally (IP) and virus will be administered locally by the IP route. Tumor burden and survival curves will be compared between treatment groups in the presence or absence of gemcitabine and in gemcitabine refractory tumors to determine if MYXV virotherapy under the three regimes mentioned above results in an enhancement of therapeutic benefits as measured by tumor burden and survival. 2) Generate recombinant MYXV armed with chemosensitizing genes that will enhance gemcitabine-based chemotherapy. Recombinant "armed" MYXVs that express deoxycytidine kinase (CDK) or the human equilibrative nucleoside transporter 1(hENT-1) will be engineered. These viruses will be characterized in vivo to determine if the expression of the transgenes enhances gemcitabine-based oncolysis of pancreatic cancer cells in the two models described above in Specific Aim 1. Tumor burden and survival curves will be compared between armed and wildtype MYXVs treated groups to determine if the use of an armed MYXV provides a therapeutic advantage over wildtype MYXV by enhancing gemcitabine-based chemotherapy in vivo. This proposal will be the first study to evaluate the oncolytic potential of MYXV in preclinical animal models of pancreatic cancer as single agent therapy and in combination with chemotherapy drugs, as well as the characterization of armed MYXV capable of sensitizing cells to gemcitabine chemotherapy. Thus, if successful, these pilot experiments will identify MYXV as an effective oncolytic virus that can be further developed as a novel, safe virotherapy for the treatment of pancreatic cancer. In particular, if the results are as positive as we anticipate, and given the excellent safety profile of MYXV, we will pursue the production of clinical grade stocks of MYXV and the filing for an investigational new drug application (IND) at the completion of the proposed study.