基于药物代谢激活转化的肿瘤靶向性核苷药物的发现及生物活性研究

Nucleoside antimetabolite drugs, the indispensible components of cancer treatment, are vitally needed to be rediscovered for improved therapeutic effect and safety. Focusing on the metabolic activation of nucleoside drug and targeting the unique abnormal accumulation of hydrogen peroxide in cancer cells, we described a novel tumor-targeting nucleotide prodrug initiated by hydrogen peroxide. A range of dFdC derivatives with arylboronic esters and cyclophosphate moiety will be designed and synthesized, one of which has been found with potential tumor selectivity and moderate cytotoxicity. Based on the pharmacokinetic research platform in our lab, the following emphasis in our project is the achievement of collaborative innovation between nucleoside medicinal chemistry and cellular pharmacokinetics. For a start, SARs around the arylboronic esters will be deeply exploited. Furthermore, proof-of-concept studies, including exploration of the metabolic mechanism and correlation between intracellular concentration of hydrogen peroxide and tumor selectivity, will be performed to validate the druglikeness of our prodrugs in normal/tumor/3D tumor cells. Most of all, as the core issue in our project, the feasibility of this novel strategy will be confirmed, the key technology in the practicability of tumor selectivity evaluation will be developed and some candidate compounds will stand out with efficient tumor-targeting property and potent antitumor activity for further preclinical exploration.

核苷类抗代谢药物在临床肿瘤治疗中不可或缺，提高其安全性与有效性迫切而有必要。申请人聚焦核苷类药物体内代谢激活转化过程，以肿瘤细胞特征性的过氧化氢异常累积为突破口，首次提出过氧化氢激活的肿瘤靶向性核苷单磷酸前药策略。本项目以dFdC为先导化合物，设计了一类含硼酸酯结构的环磷酸dFdC衍生物。前期初步实验表明，衍生物抗肿瘤作用及肿瘤靶向性趋势理想，具有深入探索价值。后期拟协同核苷药物化学与细胞药代动力学手段，对前药策略进行深层次研究：首先，拓展前药结构多样性，充分揭示SAR；其次，在正常/肿瘤/3D肿瘤细胞中，发掘前药细胞毒性与胞内过氧化氢水平的关联性，借助细胞药代动力学策略将两者桥接，阐明前药药效物质基础与代谢激活转化机制并实现成药性优化；最终解决核心科学问题，即确证新型前药策略的可行性，发展评价药物肿瘤靶向性的关键技术，并筛选出肿瘤靶向性高、抗肿瘤作用强的候选化合物以进一步开展临床前研究。

HCV基因组变异性高，药物易诱导病毒耐药。体外及临床研究（Antiviral Ther. 2013, 18, A9）均证实，索非布韦可诱导产生S282T突变耐药病毒（HCVS282T），从而导致索非布韦活性代谢物M2对NS5B聚合酶的结合力（Ki）降低50倍（J. Biol. Chem. 2007, 282, 29812）。值注意的是，M2的胞苷类似物M1对野生型HCV及突变型HCVS282T的活性（Ki值）差异却很小（图1）。据此，我们以M1为先导化合物，采用双前药策略研制了化合物4c，其对野生型HCV的抑制活性（EC50 = 0.113 μM）与索非布韦（EC50 = 0.073 μM）相当，而对HCVS282T耐药病毒的抑制活性（EC50 = 0.366 μM）要优于索非布韦（EC50 = 0.589 μM）。.本研究共合成前药衍生物32个，化合物经1H NMR、13C NMR、31P NMR、HRMS确证。本研究深入而系统地探讨了核苷酰胺结构的构效关系，重新理解了酰胺类前药在核苷类抑制剂中的应用，为今后的结构改造奠定了基础。..本研究从前药的设计合成角度，探索了①ROS激活型N4位衍生化dFdC前药的设计与合成以及②dFdC的ProTide前药NUC-1031及其衍生物的合成。为后续开展ROS激活的ProTide前药提供了坚实的理论依据与技术支持。.本研究从前药的生物活性研究角度，建立了SD大鼠血浆中Cbz-dFdC、dFdC和dFdU（2', 2'-二氟脱氧尿苷）共检测的方法学，并对该方法进行了全面的考证。所建立的同时检测SD大鼠血浆中Cbz-dFdC、dFdC和dFdU的LC-MS/MS方法可靠性良好。基于此，本研究开展了Cbz-dFdC在SD大鼠中的体内血浆药动学评价。.本研究在前药研究的同时，关注相关的有机合成领域。受到前药基团代谢激活的启发，从QMs角度，实现了两类负氢迁移反应。在负氢迁移研究过程中，本研究结合N-苯基叔胺类化合物的氧化反应与多组分Ugi反应，实现了DEAD介导的新型Ugi反应。