Virotherapy for pancreatic cancer with wildtype and armed Myxoma viruses

描述（由申请方提供）：本提案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用途。该提案以多年期十五为重点，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，对多种类型的人类体内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能够在体外感染并杀死胰腺癌细胞。我们在提案主体中提供的初步研究表明，MYXV在胰腺癌的免疫缺陷和免疫活性动物模型中均表现出有效的溶瘤活性。基于这些结果，我们试图评估MYXV与目前的化疗方案，特别是吉西他滨，胰腺癌。我们假设MYXV在体内对胰腺癌具有有效的溶瘤活性，并且可以组合和/或工程化以增强当前的化疗治疗。野生型MYXV和“武装”有化学增敏基因的重组MYXV将作为单药疗法和与目前批准用于治疗胰腺癌的化疗药物组合进行评价。 为了这项资助的目的，我们建议：1）评估野生型MYXV溶瘤在胰腺癌小鼠模型中的疗效。将对MYXV进行评价：a）作为与标准化疗相比的单一药剂疗法，B）与吉西他滨和/或厄洛替尼组合，和c）用于化疗抗性肿瘤的二线治疗疗法。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价MYXV。将通过腹膜内（IP）建立胰腺癌的免疫缺陷和免疫活性鼠模型，并通过IP途径局部给予病毒。将在存在或不存在吉西他滨的治疗组之间以及在吉西他滨难治性肿瘤中比较肿瘤负荷和存活曲线，以确定在上述三种方案下的MYXV病毒疗法是否导致通过肿瘤负荷和存活测量的治疗益处的增强。2)产生重组MYXV武装与化疗增敏基因，将加强吉西他滨为基础的化疗。将对表达脱氧胞苷激酶（CDK）或人平衡型核苷转运蛋白1（hENT-1）的重组“武装”MYXV进行工程改造。将在体内表征这些病毒，以确定转基因的表达是否在上文具体目标1中描述的两种模型中增强胰腺癌细胞的基于吉西他滨的溶瘤作用。将比较武装和野生型MYXV治疗组之间的肿瘤负荷和存活曲线，以确定武装MYXV的使用是否通过增强体内基于吉西他滨的化疗而提供优于野生型MYXV的治疗优势。 该提案将是第一项评估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的表征。因此，如果成功的话，这些试验性实验将确定MYXV是一种有效的溶瘤病毒，可以进一步开发为一种新的、安全的胰腺癌病毒疗法。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，我们将继续生产MYXV的临床级库存，并在完成拟议研究时提交研究性新药申请（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.