Targeted Prodrug Therapy of Liver Cancers

描述（由申请人提供）：肝细胞癌（HCC）和 晚期结肠直肠癌（CRC）是人类最致命的疾病之一。 CRC是美国癌症相关死亡的第二大原因， 主要是因为转移肝转移是成功治疗的主要威胁。 CRC的治疗。5-氟尿嘧啶（5-FU）。仍然是组合的主体 不能切除的肝转移的化疗。最近的研究 表明通过直接肝融合的区域性5-FU化疗 显示晚期CRC患者的缓解率和生存率有所提高， 与接受全身输注治疗的患者相比。但这 输送系统在技术上是复杂的并且是高度侵入性的。本 该申请描述了一种用于药物的新型递送系统的开发。 CRC肝转移的治疗。该方法涉及使用 由疟疾环子孢子（CS）组成的重组融合蛋白 一种与细菌胞嘧啶连接的肝细胞特异性靶向配体蛋白 脱氨酶（CD），一种“自杀基因”产物，催化合成 5-氟尿嘧啶（5-FU）从其前药5-氟胞嘧啶（5-FC）。我们有 在培养的细胞中证明，CD-CS融合蛋白可以被 通过细胞类型特异性方式内化。更重要的是， 重组蛋白稳定至少四周，并发挥旁观者细胞 前药5-FC给药后的杀伤作用。长期 稳定性可能归因于内在融合的机制， 重组蛋白包埋在游离的特定隔室中 从细胞质降解机制。为了进一步开发这个系统，我们 提出以下三个具体目标：（A）阐明机制 作为培养细胞中CD-CS长期稳定性的基础;（B） 研究靶向特异性、蛋白质稳定性和酶促活性。 正常小鼠中CD-CS的活性;以及（C）研究 CDCS/5-FC方案治疗结直肠癌肝转移 在动物模型中。我们设想，新的肝前药靶向治疗， 这里提出的战略，如果成功的话，在技术上是简单的， 非侵入性，成本效益，因此，应大大提高 治疗这些威胁生命的疾病。

DESCRIPTION (provided by applicant): Hepatocellular carcinoma (HCC) and advanced colorectal cancer (CRC) are among the most deadly diseases of mankind. CRC is the second leading cause of cancer-related death in the United States, mostly due to metastases. Hepatic metastases are the main threat for successful treatment of CRC. 5-fluorouracil (5-FU). remains the mainstay of combination chemotherapy for nonresectable liver metastases. Recent studies have demonstrated that regional 5-FU-based chemotherapy by directly hepatic fusion showed improved response rates and survival for advanced CRC patients as compared with those undergone systemic infusion treatment. However, this delivery system is technically complicated and highly invasive. The present application describes the development of a novel delivery system for the treatment of hepatic metastases of CRC. The approach involves the use of a recombinant fusion protein consisting of malarial circumsporozoite (CS) protein, a hepatocyte-specific targeting ligand, linked to bacterial cytosine deaminase (CD), a "suicide gene" product which catalyzes the synthesis of 5-fluorouracil (5-FU) from its prodrug 5-fluorocytosine (5-FC). We have demonstrated in cultured cells that the CD-CS fusion protein can be internalized by a cell type-specific manner. More importantly, the internalized recombinant protein is stable for at least four weeks and exerts bystander cell killing effects upon the administration of prodrug 5-FC. The prolonged stability is probably attributed to the mechanism that the internalized fusion recombinant protein is entrapped in particular compartment(s) that are free from cytoplasmic degradation machinery. To further develop this system, we propose the following three specific aims: (A) to elucidate the mechanism(s) underlying the prolonged stability of CD-CS in cultured cells; (B) to investigate the targeting specificity, protein stability, and enzymatic activity of CD-CS in normal mice; and (C) to investigate the efficacy of CDCS/5-FC strategy in the treatment of liver metastases of colorectal cancers in animal model. We envision that the novel hepatic prodrug targeted therapy strategy proposed here, if successfully, is technically simple and non-invasive, and cost effective, therefore, should greatly improve the treatment efficacy of these life threatening diseases.