Amphotericin B Analogs

描述（由申请人提供）：目前的抗真菌治疗受到现有药物类型的限制，这些药物可用于治疗由新兴的和相对罕见的真菌引起的全身感染，这些真菌不同于常见的致病性念珠菌、曲霉、隐球菌和联合菌科。中性粒细胞减少和免疫功能低下的患者，如血液癌、艾滋病或器官移植患者，特别容易发生侵袭性真菌感染。两性霉素B （AMB）仍然是侵袭性曲霉病、念珠菌病、毛霉病、镰孢病和隐球菌脑膜炎的重要药物，因为它的效力、广谱的活性和与它的使用相关的耐药发生率低。尽管如此，众所周知的肾毒性严重限制了这种多烯大环内酯类抗生素的长期使用。其毒性与AMB的高亲脂性有关，这使其在细胞膜上定位，破坏膜的完整性并引起离子泄漏。到目前为止，AMB的结构改变还没有产生一种被批准的药物，既能保留母体药物的效力和活性谱，又能最大限度地减少其肾毒性，并提高其水溶性，从而便于配方。Centrose建议使用其CarboConnectTM技术快速合成具有不同结构的附着糖的小分子文库，以寻求具有较小毒性和较大水溶性的新型AMB类似物，同时具有足够的效力和活性谱。在其他类型的小分子药物中，通过添加或修饰糖来改善其效力和药代动力学（PK）或减少其毒性的先例为我们的信念提供了额外的支持，即可以通过这种方式发现有吸引力的AMB类似物。我们对药物先导物发现的快速经验方法对于已知现有糖对抗真菌活性至关重要的分子是明智的，但其作用机制模型不足以为系统探索和药物先导物鉴定设计基于结构的基本原理。对文库成员体外抗真菌效力和活性谱的测定，以及潜在肾毒性的体外替代测定的结果，应该可以用于体内试验的鉴定。这将包括确定啮齿动物的急性肾毒性，抗真菌功效和PK特性。Phase的具体目标是：1)从AMB甲酯聚乙二醇的19-肟胺- och2ch2n (H)OCH3衍生物中合成一个50个成员的糖偶联物文库，代表各种单糖和双糖；2)研究了以新型单糖为原料，用氨基重排法合成AMB甲酯3′- n -糖基衍生物40元文库的可行性；3)筛选得到的新糖苷和3′- n -糖偶联物对六种重要真菌病原体的体外抗真菌活性（MIC值）；4)测定MIC =5微克/毫升化合物的红细胞溶血IC50，作为体内肾毒性的替代指标；5)在此基础上，选择多达5种AMB类似物，测定其急性肾毒性、对两种真菌病原体的抗真菌活性和啮齿动物的PK特性。公共卫生相关性：该研究旨在发现广谱抗真菌药物两性霉素B的新形式，它具有较小的毒性和较大的水溶性，以及足够的效力和活性谱，可以选择开发成一种新的抗真菌药物。

DESCRIPTION (provided by applicant): Current antifungal therapy is limited by the types of drugs available to treat systemic infections due to emerging and comparatively rare fungi different from the common strains of pathogenic Candida, Aspergillus, Cryptococcus and the Zygomycoses. Neutropenic and immunocompromised patients, such as those with hematologic cancer, AIDS or an organ transplant, are especially prone to invasive fungal infection. Amphotericin B (AMB) continues to be an important drug for invasive aspergillosis, candidemia, mucormycosis, fusariosis and Cryptococcosis meningitis because of its potency, broad spectrum of activity and the low incidence of drug resistance associated with its use. Nonetheless, the well-known nephrotoxicity of AMB severely limits long term use of this polyene macrolide antibiotic. The toxicity is related to AMB's high lipophilicity, which causes it to localize in cell membranes, disrupting membrane integrity and causing leakage of ions. The structural alterations of AMB carried out to date have not resulted in an approved drug that retains the potency and activity spectrum of the parent drug while minimizing its nephrotoxicity and improving its water solubility for ease of formulation. Centrose proposes to use its CarboConnectTM technology for rapidly synthesizing libraries of small molecules with attached sugars of diverse structure to seek novel AMB analogs with lesser toxicity and greater water solubility, together with sufficient potency and spectrum of activity. Precedents among other types of small molecule drugs for improvement of their potency and pharmacokinetics (PK), or diminishment of their toxic liability, by sugar addition or modification provide additional support for our belief that attractive AMB analogs can be discovered in this way. Our rapid, empirical approach to drug lead discovery is sensible for a molecule in which the existing sugar is known to be vital for antifungal activity, yet for which the models of the mechanism of action are inadequate to design a structure-based rationale for systematic exploration and drug lead identification. Assays of library members for antifungal potency and spectrum of activity in vitro together with the results of an in vitro surrogate assay for potential nephrotoxicity should allow identification of leads for in vivo testing. That will involve determining the acute nephrotoxicity, antifungal efficacy and PK characteristics in a rodent. The specific aims of Phase are: 1) to synthesize a 50 member library of sugar conjugates representing a diverse array of mono- and disaccharides from the 19- oximino-OCH2CH2N(H)OCH3 derivative of AMB methyl ester aglycon; 2) to examine the feasibility of synthesizing a 40 member library of 3'-N-glycosyl derivatives of AMB methyl ester by the Amidori rearrangement using novel monosaccharides; 3) to screen the resulting neoglycosides and 3'-N-sugar conjugates for antifungal activity in vitro (MIC values) against a panel of six important fungal pathogens; 4) to determine the IC50 for red blood cell hemolysis of the compounds with MIC's =5 micrograms/ml as a surrogate for in vivo nephrotoxicity; and 5) based on all of the results, to select up to 5 AMB analogs for determination of their acute nephrotoxicity, antifungal activity against two fungal pathogens and PK characteristics in a rodent. PUBLIC HEALTH RELEVANCE:The research aims to discover new forms of the broad spectrum antifungal drug, amphotericin B, with lesser toxicity and greater water solubility, together with sufficient potency and spectrum of activity to be selected for development into an new antifungal drug.