Carboxylesterase-activated Doxazolidine-prodrug for Hepatocellular Carcinoma

描述(申请人提供)：肝细胞癌(HCC)是全球最常见的癌症相关死亡原因之一。尽管它在美国的发病率相对较低，但预计未来几十年它的发病率将会加快。有人建议在体内评估一种新设计的、有针对性的前药疗法，用于过度表达羧酸酯酶CES2的癌症，重点是肝细胞癌。这种疗法是基于多沙唑胺的，这是一种阿霉素的甲醛结合物，对各种敏感和耐药(MDR表型)癌细胞的活性比阿霉素高一个数量级以上。多沙唑胺通过不同的机制诱导癌细胞死亡，对心肌细胞的毒性低于阿霉素。多沙唑胺的前体药物N-(pentyloxycarbonyl-p-aminobenzyloxycarbonyl)doxazolidine可被存在于肝、结肠、肺、肾、甲状腺和胰腺癌细胞中的CES2激活。该药物在被CES2切割之前是无效的。特异性的关键是人体血浆的稳定性预测血管系统的稳定性。该疗法旨在最大限度地提高疗效，并将包括心脏毒性在内的副作用降至最低。CES2在大鼠心肌细胞中的表达非常少，并且该前药对大鼠心肌细胞的毒性比通常用于治疗肝癌的阿霉素低两个数量级。实验的目的是改进合成和处方，建立PPD的旁观者效应，测量药代动力学，并评价其在原位小鼠肝癌模型中的疗效和毒性。疗效终点将包括肿瘤生长、存活率和细胞增殖的药效学终点，治疗后收集的肿瘤切片中的凋亡，以及DNA交联物的彗星试验。毒性终点将包括超声心动图检查、肉眼毒性测量、白细胞计数和治疗后器官组织的病理评估。初步的异种皮下移植实验表明，使用表达CES2的癌细胞抑制了小鼠肝癌和非小细胞肺癌模型的肿瘤生长。

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.