Molecular Approach in Predicting 5-Fluorouracil Efficacy

人类基因组计划的进展沿着新技术如基因芯片、自动基因测序仪和真实的时间定量PCR（RT-QPCR）的发展，导致致力于研究影响个体对药物应答的遗传差异的学科迅速扩展，称为药物基因组学。 本提案的长期目标是检查药物基因组学方法是否可用于预测III期结直肠癌患者对化疗药物5-氟尿嘧啶（5-FU）的反应和/或毒性。 最初的努力将跟进一个有希望的初步研究，在一小部分患者的肿瘤进行回顾性检查，播散性结直肠癌使用逆转录聚合酶链反应。 这项研究表明，通过定量二氢嘧啶脱氢酶（DPD）和胸苷酸合成酶（TS）的表达水平，可以确定超过90%的5-FU治疗应答者（中位生存期比无应答者长3倍以上）。 本申请的具体目的包括：具体目的1）确定肿瘤内DPD和TS表达在预测反应中的作用（至复发时间）与5-FU在III期疾病患者的前瞻性临床研究中的比较-后续研究将检查氟嘧啶途径中其他关键酶的附加值;规格目的2）测定正常组织（例如，正常肠、肝、外周血单核细胞），并与肿瘤表达水平和宿主毒性进行比较;和Spec. Aim 3）测定石蜡包埋的组织样品中的DPD和TS表达，与同时收集的快速冷冻组织进行比较，以证明该诊断方法在存档组织研究中的实用性和验证。 如果这种药物基因组学方法被证明是可行的5-FU，那么它可以扩展到潜在的其他癌症化疗药物在未来，使可能的替代疗法量身定制的个别患者。

The advancement of the Human Genome Project along with the development of new techniques such as gene chips, automated gene-sequencers and real time quantitative PCR (RT -QPCR) have resulted in a rapidly expanding discipline devoted to the study of genetic differences that affect an individual's response to drugs tenned phannacogenomics. The long-term objective of this proposal is to examine if a phannacogenomic approach can be used to predict response and/or toxicity in patients with stage III colorectal cancer to the chemotherapy drug 5-Fluorouracil (5-FU). Initial efforts will follow up on a promising preliminary study in a small population of patients with disseminated colorectal cancer whose tumors were retrospectively examined using RT- PCR. This study suggested that over 90 percent of the responders to 5-FU therapy (with a median survival over 3 times longer than non-responders) could be identified by quantitating the expression levels of dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS). The specific aims of the current application include: Spec. Aim 1) Determine the role of intratumor DPD and TS expression in predicting response (time to relapse) to 5-FU in a prospective clinical study of patients presenting with stage III disease -subsequent studies will examine the additive value of other critical enzymes in the fluoropyrimidine pathway; Spec. Aim 2) Determine DPD and TS expression in normal tissues (e.g., normal intestine, liver, peripheral blood mononuclear cells) and compare with tumor expression levels and host toxicity; and Spec. Aim 3) Determine DPD and TS expression in paraffin embedded tissue samples compared to simultaneously collected snap frozen tissue in order to demonstrate the utility and validate this diagnostic approach in studies of archival tissue. If this pharmacogenomic approach is shown to be feasible with 5-FU, it could then be extended to potentially other cancer chemotherapy agents in the future, making possible alternative therapies tailored to the individual patient.