Carboxylesterase-activated Doxazolidine-prodrug for Hepatocellular Carcinoma

描述（由申请人提供）：肝细胞癌（HCC）是世界范围内癌症相关死亡的最常见原因之一。尽管其在美国的发生率相对较低，据预测，在今后几十年中，其发病率将加速上升。研究拟在体内评估一种新设计的、靶向的前药疗法，用于过表达羧酸酯酶CES 2的癌症，重点是HCC。该疗法基于多唑烷，多柔比星的甲醛缀合物，其对多种敏感和耐药（MDR表型）癌细胞的活性比多柔比星高一个数量级以上。多恶唑烷通过不同的机制诱导癌细胞死亡，并且对心肌细胞的毒性低于阿霉素。多沙唑烷的前药，N-（戊氧基羰基-对氨基苄氧基羰基）多沙唑烷（戊基PABC-Doxaz，PPD），被存在于肝、结肠、肺、肾、甲状腺和胰腺癌细胞中的CES 2激活。该药物在被CES 2裂解前无活性。特异性的关键是人血浆中的稳定性，可预测血管系统中的稳定性。该疗法旨在最大限度地提高疗效并最大限度地减少副作用，包括心脏毒性。在大鼠心肌细胞中表达非常少的CES 2，并且前药对大鼠心肌细胞的毒性比常用于治疗HCC的阿霉素低两个数量级。设计实验以改进合成和配制，建立PPD的旁观者效应，测量药代动力学，并评估HCC原位小鼠模型中的功效和毒性。疗效终点将包括肿瘤生长、存活和细胞增殖的药效学终点、治疗后收集的肿瘤切片中的细胞凋亡和DNA交联的彗星试验。毒性终点将包括超声心动图检查、大体毒性测量、白色血细胞计数和治疗后器官组织的病理学评价。初步的皮下异种移植实验表明，使用表达CES 2的癌细胞在肝癌和非小细胞肺癌的小鼠模型中抑制肿瘤生长。

DESCRIPTION (provided by applicant): Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related deaths world-wide. In spite of its relatively low occurrence in the U.S., its incidence is predicted to accelerate during the next decades. Research is proposed to evaluate in vivo a newly designed, targeted, prodrug therapy for cancers that overexpress the carboxylesterase, CES2, with focus on HCC. The therapy is based upon doxazolidine, a formaldehyde conjugate of doxorubicin that is more than an order of magnitude more active against a variety of both sensitive and resistant (MDR phenotype) cancer cells than doxorubicin. Doxazolidine induces cancer cell death by a different mechanism and is less toxic to cardiomyocytes than doxorubicin. The prodrug of doxazolidine, N-(pentyloxycarbonyl-p-aminobenzyloxycarbonyl)doxazolidine (pentyl PABC- Doxaz, PPD), is activated by CES2 present in liver, colon, lung, kidney, thyroid, and pancreatic cancer cells. The drug is inactive until cleaved by CES2. Critical to specificity is stability in human plasma predicting stability in the vascular system. The therapy is designed to maximize efficacy and minimize side effects including cardiotoxicity. Very little CES2 is expressed in rat cardiomyocytes and the prodrug is two orders of magnitude less toxic to rat cardiomyocytes than doxorubicin which is commonly used for treatment of HCC. Experiments are designed to improve the synthesis and formulation, to establish a bystander effect for PPD, to measure the pharmacokinetics, and to evaluate the efficacy and toxicity in orthotopic mouse models of HCC. Efficacy endpoints will include tumor growth, survival and pharmacodynamic endpoints of cell proliferation, apoptosis in tumor sections collected after treatment, and Comet assay for DNA crosslinks. Toxicity endpoints will include echocardiogram examination, measures of gross toxicity, white blood cell counts and pathological evaluation of organ tissues following treatment. Preliminary subcutaneous xenograft experiments indicate tumor growth inhibition in mouse models of liver cancer and non-small cell lung cancer using cancer cells that express CES2.