Virotherapy for pancreatic cancer with wildtype and armed Myxoma viruses

描述(由申请人提供)：这项建议的目的是在临床前动物模型中研究MYXV作为潜在的溶瘤病毒治疗药物治疗胰腺癌的应用。该提案侧重于MYXV，并基于我们以前发表的报告和辅助的初步研究。MYXV是一种兔特异性痘病毒，对体内多种类型的人类癌症模型具有溶瘤活性，包括脑瘤、黑色素瘤和横纹肌样瘤。此外，我们最近报道了MYXV在体外能够感染和杀伤胰腺癌细胞。我们在提案正文中提供的初步研究表明，MYXV在免疫缺陷和免疫活性良好的胰腺癌动物模型中都显示出强大的溶瘤活性。基于这些结果，我们试图评估MYXV联合目前的化疗方案，特别是吉西他滨治疗胰腺癌。我们推测MYXV将在体内对胰腺癌具有强大的溶瘤活性，并可能被联合和/或设计以加强目前的化疗治疗。野生型MYXV和携带化疗增敏基因的重组MYXV(S)将作为单药疗法进行评估，并与目前批准用于治疗胰腺癌的化疗药物联合使用。为此，我们建议：1)评估野生型MYXV溶瘤在小鼠胰腺癌模型中的疗效。MYXV将被评估为：a)作为与标准化疗相比的单一药物疗法，b)与吉西他滨和/或厄洛替尼联合使用，以及c)作为化疗耐药肿瘤的二线疗法。这些实验涉及对胰腺癌最常见的一线化疗的使用，因此将在临床相关方案的背景下评估MYXV。将建立免疫缺陷和免疫活性的小鼠胰腺癌模型(IP)，病毒将通过IP途径局部给药。在存在或不存在吉西他滨的情况下，以及在吉西他滨难治性肿瘤中，治疗组之间的肿瘤负担和生存曲线将进行比较，以确定上述三种方案下的MYXV病毒疗法是否能够提高以肿瘤负担和存活率衡量的治疗效益。2)产生携带化疗增敏基因的重组MYXV，以加强基于吉西他滨的化疗。表达脱氧胞苷激酶(CDK)或人类平衡核苷转运蛋白1(hent-1)的重组“武装”MYXV将被设计出来。这些病毒将在体内进行表征，以确定在上述两种模型中，转基因的表达是否在特定目的1中增强了基于吉西他滨的胰腺癌细胞的裂解。将比较武装和野生型MYXV治疗组的肿瘤负担和生存曲线，以确定使用武装MYXV是否通过增强体内基于吉西他滨的化疗而提供比野生型MYXV更好的治疗优势。这项建议将是第一次评估MYXV在胰腺癌临床前动物模型中作为单一药物治疗和与化疗药物联合使用的溶瘤潜力，以及武装MYXV能够使细胞对吉西他滨化疗敏感的特征。因此，如果成功，这些试验性实验将确定MYXV是一种有效的溶瘤病毒，可以进一步开发为治疗胰腺癌的新型、安全的病毒疗法。特别是，如果结果如我们预期的那样积极，并考虑到MYXV良好的安全性，我们将继续生产MYXV的临床级库存，并在拟议的研究完成后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.