Mechanistic and Translational Studies of PR-104:A New Hypoxia Activated Cytotoxin

该项目的目标是用一种新的、高效的方法进行机理和转化研究。 低氧激活药物PR-104，特别是在评估其与放射治疗组合的潜力方面， 吉西他滨PR-104是我们的合作者最近发现的二硝基苯甲酰胺类化合物（DNBM） Drs.丹尼和威尔逊，与目前的缺氧细胞毒素原型相比， 替拉扎明（TPZ），包括大量的旁观者杀伤，使其对有氧以及 实体瘤中的低氧细胞。它于2006年1月进入1期临床试验。结合一个 低氧细胞毒素与常规抗癌疗法的结合是基于大多数人实体瘤 具有低氧水平（缺氧）的区域，并且这些区域中的细胞对辐射杀伤具有抗性 和许多化疗药物。TPZ已经证明了与 放疗和顺铂化疗。我们的初步研究表明，PR-104优于上级 TPZ与分次放疗联合治疗两种不同的人肿瘤异种移植物， 大量的单一代理活动。我们将重点关注头颈癌和胰腺癌，前者与 分次放疗和后者与吉西他滨。放射治疗的肿瘤疗效研究将 用PR-104与TPZ平行的不同人头颈肿瘤异种移植物进行， 比较它们的相对疗效，PR-104与吉西他滨联合使用的研究将在 用胰腺异种移植物作为皮下和原位模型进行。我们的具体目标是：（1） 比较PR-104和TPZ在增强头颈部分次照射中的疗效 异种移植物，2）通过测定DMA来测量活性PR-104代谢物在肿瘤中的分布 通过碱性彗星试验测定链间交联3）以测定PR-1的功效和作用机制。 104与吉西他滨联合治疗胰腺肿瘤异种移植物，4）以确定 PR-104在有或没有辐射的情况下的活性可以通过使用血管内皮细胞增加肿瘤缺氧来增加， 靶向剂5），以确定使用NTR可以增加PR-104活性的程度 6）检验PR-104的GI毒性可以通过以下方式降低的假设： 减少肠道菌群。该项目直接适用于人类健康：其基本原理是 与TPZ相同，TPZ是第一种显示临床益处的缺氧细胞毒素，但PR-104似乎上级TPZ。 因此，与TPZ相比，TPZ具有更大程度上提高癌症治愈率的潜力

The goal of this project is to perform mechanistic and translational studies with a new and highly effective hypoxia-activated drug, PR-104, particularly in evaluating its potential for combination with radiotherapy and with gemcitabine. PR-104 is a dinitrobenzamide mustards (DNBM), recently discovered by our collaborators Drs. Denny and Wilson, with improved properties over the current prototype of a hypoxic cytotoxin, tirapazamine (TPZ), including a substantial bystander killing that gives it activity against aerobic as well as hypoxic cells in solid tumors. It entered Phase 1 clinical trials in January 2006. The benefit of combining a hypoxic cytotoxin with conventional anticancer therapy is based on the fact that most human solid tumors have regions at low oxygen levels (hypoxia) and the cells in these regions are resistant to killing by radiation and many chemotherapeutic drugs. TPZ has already demonstrated clinical benefit in combination with radiotherapy and cisplatin based chemotherapy. Our preliminary studies show that PR-104 is superior to TPZ in combination with fractionated radiation with two different human tumor xenografts as well as having substantial single agent activity. We will focus on head and neck and pancreatic cancers, the former with fractionated radiation and the latter with gemcitabine. The tumor efficacy studies with radiation will be performed with different human head and neck tumor xenografts with PR-104 in parallel with TPZ in order to compare their relative efficacies, and the studies with PR-104 in combination with gemcitabine will be performed with pancreatic xenografts both as subcutaneous and orthotopic models. Our specific aims are 1) to compare the efficacy of PR-104 and TPZ in potentiating fractioned irradiation to head and neck xenografts, 2) to measure the distribution of active PR-104 metabolites in tumors by assaying DMA interstrand crosslinks by the alkaline comet assay 3) to assay the efficacy and mechanism of action of PR- 104 in combination with gemcitabine with pancreatic tumor xenografts, 4) to determine the extent to which the activity of PR-104 with or without irradiation can be increased by increasing tumor hypoxia using vascular targeting agents 5) to determine the extent to which the activity of PR-104 can be increased using NTR expressing C.sporogenes, and 6) to test the hypothesis that the Gl toxicity of PR-104 can be reduced by reduction of intestinal microflora. This project has direct applicability to human health: It's rationale is the same as that of TPZ, the first hypoxic cytotoxin to show clinical benefit, yet PR-104 appears to be superior to TPZ, and therefore has the potential of improving cancer cure rates to a greater extent than does TPZ