Carboxylesterase-activated Doxazolidine-prodrug for Hepatocellular Carcinoma

描述（由申请人提供）：肝细胞癌（HCC）是全世界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，但预计其发生率在未来几十年内将会加速。拟议的研究旨在体内评估一种新设计的靶向前药疗法，用于治疗过度表达羧酸酯酶 CES2 的癌症，重点关注 HCC。该疗法基于多恶唑烷，这是一种阿霉素的甲醛缀合物，对多种敏感和耐药（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比阿霉素小。多恶唑烷的前药 N-(戊氧基羰基-对氨基苄氧基羰基)多恶唑烷 (戊基 PABC-Doxaz，PPD) 被肝癌、结肠癌、肺癌、肾癌、甲状腺癌和胰腺癌细胞中的 CES2 激活。该药物在被 CES2 裂解之前处于非活性状态。特异性的关键是人血浆的稳定性，可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最大限度地减少包括心脏毒性在内的副作用。 CES2 在大鼠心肌细胞中表达非常少，并且该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。实验旨在改进合成和配方，建立 PPD 的旁观者效应，测量药代动力学，并评估 HCC 原位小鼠模型的功效和毒性。功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以及 DNA 交联的彗星测定。毒性终点将包括超声心动图检查、总体毒性测量、白细胞计数和治疗后器官组织的病理学评估。初步皮下异种移植实验表明，使用表达 CES2 的癌细胞可抑制肝癌和非小细胞肺癌小鼠模型中的肿瘤生长。

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.