Leptomycin B Development for Cancer Therapy

描述（由申请人提供）： 长期目标：Leptomycin B（LMB）为将聚酮化合物天然产物开发成具有新作用机制的抗癌药物提供了机会。这种微生物代谢物通过与CRM 1（syn.输出蛋白1）并抑制其穿梭蛋白复合物穿过核膜的能力。 许多细胞信号传导过程可能受到影响，包括癌症发生和发展以及病毒复制中的特定步骤所必需的过程。LMB与伊马替尼（格列卫）（一种用于治疗慢性粒细胞白血病（CML）的蛋白酪氨酸激酶抑制剂）协同作用并克服其获得性耐药性的能力已在体外得到证实。这表明LMB可以与其他通过癌细胞特异性机制起作用的药物有效结合。 LMB生产批次的质量变异性阻碍了临床前研究，这可能是由于杂质或次要同系物造成的。这也可能损害了LMB在1994-95年进行的I期临床试验中的性能。为了克服这一局限性，我们建议（i）开发一种可靠的发酵工艺来生产高纯度的LMB，以及（ii）使用Kosan专有的聚酮合酶（PKS）基因操作技术 在异源宿主中表达LMB生物合成基因或合适的工程化形式，以便仅产生LMB。圣地亚哥大学和国家癌症研究所的合作者将评估格列卫与纯化LMB在CML动物模型中联合给药的疗效，并在合适的动物系统中进行LMB的临床前药代动力学和毒理学研究。 第一阶段研究的具体目标：（1）利用链霉菌ATCC 39366通过优化的发酵工艺生产至少95%化学纯度的LMB。(2)在天蓝色链霉菌中表达天然LMB生物合成基因，或设计用于增强LMB选择性形成的工程化形式，以便专门生产LMB。(3)向UCSD和NCI合作者提供纯化的LMB进行生物学评价。如果我们能在本地生产商或S.我们将继续进行LMB的临床前开发或在II期研究中发现和开发LMB类似物。

DESCRIPTION (provided by applicant): Long-range goals: Leptomycin B (LMB) offers the opportunity to develop a polyketide natural product into a cancer drug with a novel mechanism of action. This microbial metabolite inhibits protein export from the cell nucleus by binding tightly to CRM1 (syn. exportin 1) and inhibiting its ability to shuttle protein complexes across the nuclear membrane. Numerous cell signalling processes can be affected, including ones essential to specific steps in the onset and development of cancer as well as viral replication. The ability of LMB to synergize with and overcome acquired resistance to imatinib (Gleevec), a protein tyrosine kinase inhibitor used to treat chronic myelogenous leukemia (CML), has been demonstrated in vitro. This suggests that LMB could be combined effectively with other drugs that act by cancer cell specific mechanisms. Preclinical studies have been hampered by variability of the quality of LMB production lots, which were probably due to impurities or minor congeners. This may have also compromised the performance of LMB in a Phase I clinical trial carried out in 1994-95. To overcome this limitation, we propose (i) to develop a reliable fermentation process for producing highly pure LMB and (ii) to use Kosan's proprietary polyketide synthase (PKS) gene manipulation technology to express the LMB biosynthesis genes, or a suitably engineered form, in a heterologous host so as to produce only LMB. Collaborators at the University of San Diego and the National Cancer Institute will assess the efficacy of co-administration of Gleevec with purified LMB in an animal model of CML, and conduct preclinical pharmacokinetic and toxicology studies of LMB in a suitable animal system. Specific aims of Phase I research: (1) Produce LMB of at least 95% chemical purity by an optimized fermentation process with Streptomyces sp ATCC 39366. (2) Express the native LMB biosynthetic genes, or an engineered form designed to enhance the selective formation of LMB, in Streptomyces coelicolor so as to produce LMB exclusively. (3) Provide purified LMB to UCSD and NCI collaborators for biological evaluation. If we can produce highly pure LMB in consistent quality in the native producer or in S. coelicolor, we will proceed with preclinical development of LMB or the discovery and development of an LMB analog in Phase II research.