TUMOR SENSITIZATION TO PURINE ANALOGS BY E.COLI PNP

描述(申请人的描述) 在肿瘤细胞中选择性表达可产生有毒药物的非人类基因正被考虑用于治疗各种对现有化疗药物无效的实体肿瘤。我们开发了一种利用大肠杆菌嘌呤核苷磷酸化酶(PNP)底物特性来激活嘌呤核苷前体药物(E. 大肠杆菌PNP识别含腺嘌呤核苷为底物，而人PNP不识别底物)。我们的方法具有许多区别于其他自杀基因治疗策略的特点(例如，高旁观者活性、产生的有毒嘌呤的效力、对非增殖肿瘤细胞的活性、1剂化合物后的强大抗肿瘤效果)。在过去的四年里，我们从一项新的体外观察到在动物肿瘤模型中成功地展示了这种方法的可行性。我们认为，大肠杆菌PNP基因治疗策略的独特属性与 一些现有的载体可能会在抗肿瘤治疗方面产生重大改进。这一应用的长期目标是将这一想法发展成一种有用的抗肿瘤疗法。为了实现这一目标，我们有三个主要目标：1)在动物肿瘤模型中证明这种方法的可行性；2)创造更好的前药/酶组合，以改进我们在大肠杆菌PNP方面所取得的成功；以及3.增加对这一策略的基本理解。 该NCDDG由4个程序和一个内核组成。分子生物学计划的目标是开发选择性地将基因输送到整个动物的肿瘤细胞中的程序；生物化学计划是充分描述嘌呤核苷类似物的生化药理及其各自的基础，以帮助合理设计新的前药； 化学计划是设计和合成无毒的嘌呤核苷前药，这些药物被在这一应用中开发的新酶切割成有毒的嘌呤；X射线结晶学计划是确定PNP的结构，以帮助设计新的化合物和酶；化疗的核心是在分子生物学计划的帮助下，在相关动物肿瘤模型中评估NCDDG开发的前药的抗肿瘤活性。因此，NCDDG的总体目的是利用新出现的向先前存在的肿瘤输送基因的机制、令人兴奋的临床前疗效数据以及发现新的酶/前体药物组合。

DESCRIPTION (Applicant's Description) The selective expression in tumor cells of non-human genes that can produce toxic drugs is being considered for the treatment of various solid tumors that are refractory to existing chemotherapeutic agents. We have developed a strategy utilizing the substrate characteristics of E. coli purine nucleoside phosphorylase (PNP) to activate purine nucleoside prodrugs (E. coli PNP recognizes adenine-containing nucleosides as substrates whereas human PNP does not). Our approach has numerous characteristics that distinguish it from the other suicide gene therapy strategies (for example, high bystander activity, potency of the toxic purines generated, activity against non-proliferating tumor cells, potent anti-tumor effects after 1 dose of compound). During the last four years we have progressed from a new in vitro observation to successful demonstration of the feasibility of this approach in animal tumor models. We believe that the unique attributes of the E. coli PNP gene therapy strategy in conjunction with some of the existing vectors could result in significant improvements in antitumor therapy. The long-term objective of this application is to develop this idea into a useful anti-tumor therapy. To reach this objective we have three major goals: 1) to demonstrate the feasibility of this approach in animal tumor models; 2) to create better prodrug/enzyme combinations to improve upon the success that we have had with E. coli PNP; and 3. to generate an increased basic understanding of this strategy. This NCDDG is composed of 4 programs and one core. The objective of the: Molecular Biology Program is to develop procedures to selectively deliver genes into tumor cells of whole animals; Biochemistry Program is to fully characterize the biochemical pharmacology of the purine nucleoside analogs and their respective bases to aid in the rational design of new prodrugs; Chemistry Program is to design and synthesize nontoxic purine nucleoside prodrugs that are cleaved to toxic purines by new enzymes developed in this application; X-ray Crystallography Program is to determine the structure of PNP's to aid in the design of new compounds and enzymes; and Chemotherapy Core is to evaluate the antitumor activity of the prodrugs developed in this NCDDG in relevant animal tumor models developed with the aid of the Molecular Biology Program. The overall NCDDG is therefore intended to capitalize on emerging mechanisms for delivery of genes to pre-existing tumors, exciting preclinical efficacy data, and the discovery of novel enzyme/prodrug combinations.