NEW APPROACHES TO ANTIFOLATE CHEMOTHERAPY

抗叶酸化疗的新方法

• 批准号: 2330679
• 负责人: ANDRE ROSOWSKY
• 金额: $ 25.35万
• 依托单位: DANA-FARBER CANCER INST
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-04-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2330679
• 关键词: aminopterin; dihydrofolate reductase; drug adverse effect; drug design /synthesis /production; drug metabolism; drug resistance; drug screening /evaluation; enzyme inhibitors; folate antagonist; homocysteine; laboratory mouse; ligands; membrane transport proteins; methotrexate analog; neoplasm /cancer pharmacology; pharmacokinetics; prodrugs

This laboratory has been engaged in a program of design, synthesis, and biological evaluation of derivatives and structural analogs of classical and nonclassical antifolates with the aim of generating new agents with improved pharmacological and therapeutic properties or a qualitatively altered spectrum of antitumor activity. The research involves collaborative interactions with a number of other groups sharing an interest in innovative approaches to antifolate drug discovery. A major goal of the work is to find compounds with increase ability to accumulate in tumor cells resistant to classical antifolates like methotrexate (MTX) by virtue of a defect in drug uptake. It is expected that cross resistance between such compounds and MTX will be low, and that they will have potential clinical utility against tumors with either natural or acquired MTX resistance based on defects in transport and/or polyglutamylation. Secondly, since an important form of MTX resistance is known to involve structural mutations in dihydrofolate reductase (DHFR) resulting in weak binding of classical antifolates of the MTX type, another goal of the work is to find compounds that will bind more tightly than MTX to these DHFR variants. Finally, since it has become widely recognized that inhibition of folate pathway enzymes other than DHFR, especially thymidylate synthase (TS) and glycinamide ribotide formyltransferase (GART), offers a powerful alternative approach to the selective killing of tumor cells and the circumvention of MTX resistance based on DHFR mutation or increased production of wild-type enzyme, a third goal of research is to generate compounds that inhibit these enzymes instead of, or in addition to, DHFR. An important lead already uncovered during this project has been the water-soluble nonclassical DHFR inhibitor N-alpha-(4-amino-4- deoxypteroyl)-N-delta-hemiphthaloyl-L-ornithine (PT523, NSC633713 ). This structurally unique antifolate is more potent than MTX against a broad range of cultured human solid tumor cells, including cells 10- to 30-fold resistant to MTX by virtue of either impaired transport or increased DHFR activity -- a level of MTX resistance typically associated with acquired resistance in patients. Greater potency and decreased growth has also been shown with PT523 in vivo against murine tumors and human tumor xenografts in athymic nude mice. Because PT523 lacks a glutamate side chain it cannot form polyglutamates; thus, unlike classical antifolates, it is not a prodrug and does not rely on polyglutamation to manifest its full impact on one-carbon metabolism. Moreover, unlike lipophilic nonclassical antifolates such as trimetrexate and piritrexim, PT523 retains activity against cells with the classical multidrug resistance (MDR) phenotype based on high P-glycoprotein expression; thus it is unlikely to be cross- resistant to a number of widely prescribed antineoplastic natural products such as anthracyclines, vinca alkaloids, podophyllotoxins camptothecins, and taxanes. On the basis of these very exciting results, a major focus of the next grant cycle will be the synthesis of second-generation analogs and targeted prodrugs of PT523 for in vitro/in vivo testing and SAR analysis. Structural modification of PT523 will feature changes in the side chain, aryl moiety, bridge, and B-ring. Targeted prodrugs will include peptide derivatives that are designed to release the parent drug in vivo after cleavage by tumor-targeted MoAb-conjugated peptidases. Efforts will also be made to discover analogs that bind well to mutant DHFRs that are insensitive to standard classical and nonclassical antifolates. The focus of this effort will be on the synthesis of molecules in which the bridge has been moved from the 6- to the 5- position of the B-ring. The longterm goal of this program is to discover and develop new and novel antifolates for the treatment of human cancer.

该实验室一直致力于设计、合成和研究项目 经典衍生物和结构类似物的生物学评价 和非经典抗叶酸剂，旨在产生新的药物 改善药理和治疗特性或定性 改变抗肿瘤活性谱。研究涉及 与许多其他共享同一个群体的协作互动 对抗叶酸药物发现的创新方法感兴趣。一个专业 这项工作的目标是寻找具有增强积累能力的化合物 对甲氨蝶呤 (MTX) 等经典抗叶酸药物耐药的肿瘤细胞 由于药物吸收缺陷。预计交叉阻力 此类化合物与 MTX 之间的差异会很低，并且它们会具有 针对天然或获得性肿瘤的潜在临床用途 基于运输和/或多聚谷氨酰化缺陷的 MTX 耐药性。 其次，由于已知 MTX 耐药性的一种重要形式涉及 二氢叶酸还原酶（DHFR）的结构突变导致弱 MTX 类型的经典抗叶酸剂的结合，是该工作的另一个目标 就是找到比 MTX 与这些 DHFR 结合更紧密的化合物 变种。最后，由于人们普遍认识到抑制 除 DHFR 之外的叶酸途径酶，尤其是胸苷酸合酶 (TS) 和甘氨酰胺核苷酸甲酰基转移酶 (GART)，提供了强大的 选择性杀死肿瘤细胞的替代方法 基于 DHFR 突变或增加来规避 MTX 耐药性 生产野生型酶，研究的第三个目标是产生 替代 DHFR 或与 DHFR 一起抑制这些酶的化合物。 在这个项目中已经发现的一个重要线索是 水溶性非经典 DHFR 抑制剂 N-α-(4-氨基-4- 脱氧蝶酰基）-N-δ-半邻苯二甲酰基-L-鸟氨酸（PT523，NSC633713）。这 结构独特的抗叶酸药比 MTX 更有效地对抗广泛的 一系列培养的人类实体瘤细胞，包括 10 至 30 倍的细胞 由于转运受损或 DHFR 增加而对 MTX 产生耐药性 活动——通常与获得性相关的 MTX 耐药水平 患者的抵抗力。更大的效力和更低的增长也已被 显示 PT523 在体内对抗小鼠肿瘤和人类肿瘤异种移植物 在无胸腺裸鼠中。因为 PT523 缺乏谷氨酸侧链，所以不能 形成聚谷氨酸盐；因此，与经典的抗叶酸剂不同，它不是 前药，不依赖多聚谷氨酸来发挥其全部作用 关于一碳代谢。此外，与亲脂性非经典 抗叶酸剂，如三甲曲沙和吡曲辛，PT523 保留活性 针对具有经典多药耐药性 (MDR) 表型的细胞 基于高 P-糖蛋白表达；因此它不可能是交叉的 对许多广泛使用的抗肿瘤天然产物具有耐药性 例如蒽环类、长春花生物碱、鬼臼毒素、喜树碱、 和紫杉烷类。在这些非常令人兴奋的结果的基础上，一个主要焦点 下一个资助周期将是第二代类似物的合成 以及用于体外/体内测试和 SAR 的 PT523 靶向前药 分析。 PT523的结构修改将带来以下变化： 侧链、芳基部分、桥和B环。靶向前药将 包括旨在释放母体药物的肽衍生物 在体内被靶向肿瘤的 MoAb 缀合肽酶裂解后。 还将努力发现与突变体良好结合的类似物 对标准经典和非经典不敏感的 DHFR 抗叶酸剂。 这项工作的重点将是综合 桥已从 6- 移至 5- 的分子 B 环的位置。 该计划的长期目标是发现 并开发用于治疗人类癌症的新型抗叶酸剂。