Molecular Approach in Predicting 5-Fluorouracil Efficacy

人类基因组计划的进展以及基因芯片、自动基因测序仪和实时定量PCR （RT -QPCR）等新技术的发展，导致了一个快速发展的学科，致力于研究影响个体对药物反应的遗传差异，即基因基因组学。本研究的长期目标是研究是否可以使用基因组学方法来预测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。最初的努力将在一项有希望的初步研究中进行后续研究，该研究是在一小部分使用RT- PCR回顾性检查肿瘤的弥散性结直肠癌患者中进行的。该研究表明，通过定量检测二氢嘧啶脱氢酶（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）。当前申请的具体目的包括：目标1)在一项III期疾病患者的前瞻性临床研究中，确定肿瘤内DPD和TS表达在预测5-FU反应（复发时间）中的作用——后续研究将检验氟嘧啶途径中其他关键酶的添加价值；明确目标2)测定DPD和TS在正常组织（如正常肠、肝、外周血单核细胞）中的表达，并与肿瘤表达水平和宿主毒性进行比较；目的3)与同时收集的快速冷冻组织相比，测定石蜡包埋组织样本中的DPD和TS表达，以证明该诊断方法在档案组织研究中的实用性和有效性。如果这种药物基因组学方法在5-FU中被证明是可行的，那么它就可以在未来扩展到其他潜在的癌症化疗药物，使针对个体患者的替代疗法成为可能。

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.