DIOXOLANE NUCLEOSIDES AS ANTIVIRAL AGENTS

描述（由申请人提供）：随着时间的推移，HIV有效地对抗病毒药物产生耐药性。因此，迫切需要更好的药物来治疗艾滋病毒，特别是耐药的艾滋病毒菌株。最近，D-FDOC，（-）-β-D-5-氟-1-[2-（羟甲基）-1，3-二氧戊环-4-基]胞嘧啶，显示出对HIV耐药株具有有效的体外活性（对HIV-1 LAI的EC 50为0.04 μ M），而不与3 TC、AZT或奈韦拉平产生交叉耐药性。D-FDOC在培养物中对HBV也有效。在原代小鼠骨髓细胞中，即使在300 μ M下，D-FDOC也没有表现出乳酸产生的增加。相比之下，用L-FDOC处理导致相对于未处理的对照增加> 300倍。制备对映体纯的D-FDOC以避免合成中污染的L-FDOC的潜在毒性是重要的。然而，D-FDOC的临床前和临床开发由于缺乏大规模制备这种核苷的有效方法而受到阻碍。因此，在第一阶段，我们将开发用于大规模合成D-二氧戊环核苷的简便方法。这种化学方法不仅对Pharmasset有用，而且对开发二氧戊环核苷的其他公司也有用，例如Triangle Pharmaceuticals的（-）-beta-D-2，6-二氨基-9-[2-（羟甲基）-1，3-二氧戊环-4-基]嘌呤（DAPD）。Ohrui等人报道，2 '-脱氧-4'-C-乙炔基-核糖核苷在体外显示出有效的抗HIV-1活性，EC 50值范围为0.0003-0.03 μ M。 还显示2 '-C-甲基-核糖-戊呋喃糖基胞嘧啶具有有效的抗黄病毒活性。基于这些发现，我们提出设计和合成新的外消旋二氧戊环核苷，特别是2 ′-C-乙炔基和5 ′-C-甲基取代的二氧戊环核苷作为丙型肝炎病毒（HCV）和/或HIV的I期抗病毒剂。根据这些化合物的生物学测试结果，我们将使用新的工艺化学来鉴定用于合成的更具活性的对映异构体。在第二阶段，我们将采用我们最好的方法大规模合成D-FDOC以及最有前途的新二氧戊环核苷，以进一步开发IND申请。

DESCRIPTION (provided by applicant): HIV efficiently develops resistance to antiviral agents over time. Thus, there is an urgent need for better agents to treat HIV, especially drug-resistant strains of HIV. Recently, D-FDOC, (-)-beta-D-5-fluoro-1-[2-(hydroxymethyl)-1,3-dioxolan-4-yl]cytosine, was shown to have potent in vitro activity against drug-resistant strains of HIV (EC50 against HIV-1LAI is 0.04, mu M) without producing cross-resistance with 3TC, AZT or nevirapine. D-FDOC is also effective against HBV in culture. In primary mouse bone marrow cells, D-FDOC demonstrated no increase in lactic acid production even at 300 mu M. In contrast, treatment with L-FDOC resulted in a > 300-fold increase relative to untreated control. It is important to prepare enantiomerically pure D-FDOC to avoid potential toxicity from contaminated L-FDOC in the synthesis. However, pre-clinical and clinical development of D-FDOC has been hampered by the lack of an efficient procedure for large-scale preparation of this nucleoside. Thus, during Phase I, we will develop facile methods for the large-scale synthesis of D-dioxolane nucleosides. This chemistry will be useful not only to Pharmasset, but to other companies developing dioxolane nucleosides such as (-)-beta-D-2,6- diamino-9-[2-(hydroxymethyl)-1,3-dioxolan-4-yl]purine (DAPD) by Triangle Pharmaceuticals. Ohrui et al reported that 2'-deoxy-4'-C-ethynyl-ribo-nucleosides showed potent activity against HIV-1 in vitro with EC50 values ranging from 0.0003-0.03 mu M. 2'-C-Methyl-ribo-pentofuranosylcytosine was also shown to have potent anti-flavivirus activity. Based on these findings, we propose to design and synthesize novel racemic dioxolane nucleosides, in particular 2'-C-ethynyl and 5'-C-methyl substituted dioxolane nucleosides as antiviral agents for hepatitis C virus (HCV) and/or HIV in Phase I. Based on results from the biological testing of these compounds, we will then identify more active enantiomers for synthesis using the new process chemistry. In Phase II, we will apply our best methodology for large-scale synthesis of D-FDOC as well as the most promising new dioxolane nucleoside for further development towards an IND application.