TUMOR SENSITIZATION TO PURINE ANALOGS BY E.COLI PNP

申请人的描述（Applicant's Description） 正在考虑在肿瘤细胞中选择性表达可产生毒性药物的非人基因，用于治疗现有化疗剂难治的各种实体瘤。 我们开发了一种利用E. coli嘌呤核苷磷酸化酶（PNP）活化嘌呤核苷前药（E. 大肠杆菌PNP识别含腺嘌呤的核苷作为底物，而人PNP不识别）。 我们的方法具有许多将其与其他自杀基因治疗策略区分开的特征（例如，高旁观者活性、所产生的毒性嘌呤的效力、针对非增殖肿瘤细胞的活性、1剂化合物后的有效抗肿瘤作用）。 在过去的四年中，我们已经从一个新的体外观察进展到成功证明这种方法在动物肿瘤模型中的可行性。 我们相信，E.大肠杆菌PNP基因治疗策略联合 一些现有的载体可导致抗肿瘤治疗的显著改进。 本申请的长期目标是将这一想法发展成一种有用的抗肿瘤疗法。 为了达到这一目标，我们有三个主要目标：1）证明这种方法在动物肿瘤模型中的可行性; 2）创造更好的前药/酶组合，以改善我们在E. coli PNP;和3.以加深对这一战略的基本理解。 该NCDDG由4个程序和一个核心组成。 本组织的目标是：分子生物学项目是开发选择性地将基因递送到整个动物的肿瘤细胞中的程序;生物化学项目是充分表征嘌呤核苷类似物及其各自的碱基的生化药理学，以帮助合理设计新的前药; 化学程序是设计和合成无毒的嘌呤核苷前药，这些前药被本申请中开发的新酶裂解为毒性嘌呤; X射线晶体学程序是确定PNP的结构，以帮助设计新化合物和酶;和化疗的核心是评价在该NCDDG中开发的前药在借助本发明开发的相关动物肿瘤模型中的抗肿瘤活性。分子生物学计划。 因此，整体NCDDG旨在利用将基因递送至既存肿瘤的新兴机制、令人兴奋的临床前疗效数据以及新型酶/前药组合的发现。

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.