Exploiting bacterial uptake as a universal platform for antibacterial development

 描述(申请人提供)：多重耐药革兰氏阴性病原体已被疾控中心和世卫组织宣布为一种主要的、新出现的健康危机。感染这些细菌，包括铜绿假单胞菌、鲍曼不动杆菌和超广谱β-内酰胺酶(ESBL)肠杆菌科细菌，与感染抗生素敏感的细菌相比，死亡率增加约60%。令人担忧的是，耐药感染的流行率正在稳步攀升，目前在美国一些地区达到了20%。在这种背景下，迫切需要新型抗菌剂。针对革兰氏阴性病原体的新的先导发现面临的最大障碍是药物通过外膜的渗透性差，以及由于多余的外排泵系统而导致的药物外排速度快，因为它阻止了药物在细胞内积累，从而阻止了整个细胞的活动。在靶向药物发现工作上的重大投资已经确定了许多针对保守的细菌酶靶点的有效线索，但革兰氏阴性病原体的低细胞内药物浓度注定了它们的发展。在将有效的生化效力转化为有效的细胞活性从而无毒性的体内活性方面的这些挑战已经在整个行业中被注意到，并一致导致战略决定放弃这一方法，尽管有大量其他有希望的抗菌线索。一种将这种药物引线输送到细菌细胞质中的方法将会发生变化，因为它将利用已经在优化这种引线方面进行的巨大投资。此外，可以应用于任何这种铅的这种输送的通用平台将改变抗生素流水线的状态。我们认为，开发天然的、活跃的细菌摄取系统是一个潜在的强大战略，可以作为一个通用的平台，将小分子输送到细菌细胞质中。通过将对其同源细菌酶靶标有效的小分子抗生素与这些摄取系统输入的因子结合，可以获得足够的细胞内抗生素浓度。我们提出了一个基于铜绿假单胞菌中高度保守和冗余的维生素B12摄取系统的新系统。这些系统有效地将钴胺衍生物从细胞外环境输送到细胞质，并能够输送一系列钴胺衍生物。我们将开发优化的维生素B12-抗菌结合物，这些结合物被编程为最佳暴露并将宿主细胞摄取的毒性降至最低。此外，我们将利用高度优化的新型抗菌药物和先导药物，这些药物和先导药物的研发障碍仅限于胞浆递送。该计划的成功实施不仅将为IND研究提供新的革兰氏阴性抗菌剂，还将展示主动转运结合药物输送方法改变抗菌药物发现的潜力。

 DESCRIPTION (provided by applicant): Multidrug resistant Gram-negative pathogens have been declared a leading, emerging health crisis by the CDC and WHO. Infections with these organisms, including Pseudomonas aeruginosa, Acinetobacter baumanni, and extended-spectrum beta-lactamase (ESBL) Enterobacteriaceae, carry ~60% increased mortality compared to infection with antibiotic-sensitive organism. Alarmingly, the prevalence of infection with resistant forms is steadily climbing, now >20% in some regions of the United States. In this setting, novel antibacterial agents are desperately needed. The most significant hurdle facing novel lead discovery against Gram-negative pathogens is poor drug permeation through the outer membrane, coupled with high rates of drug efflux due to redundant efflux pump systems, as it prevents intracellular drug accumulation and thus whole cell activity. Significant investments in target-based drug discovery efforts have identified many potent leads against conserved bacterial enzyme targets, but low intracellular drug concentrations in Gram-negative pathogens have doomed their development. These challenges in translating potent biochemical potency to effective cellular activity and thus in vivo activity without toxicity have been noted across the industry and uniformly resulted in strategic decisions to abandon this approach, despite the abundance of otherwise promising antibacterial leads. An approach to deliver such drug leads into the bacterial cytoplasm would be transforming, as it would leverage the tremendous investment that has already been made in the optimization of such leads. Further, a general platform for such delivery that could be applied to any such lead would transform the state of the antibiotic pipeline. We suggest that exploitation of native, active bacterial uptake systems is a potentially powerful strategy that can serve as a universal platform to deliver small molecules into the bacterial cytoplasm. By conjugating small molecule antibiotics that are potent for their cognate bacterial enzymatic target to the factor that is imported by these uptake systems, sufficient intracellular concentrations of the antibiotic can be achieved. We propose a novel system founded on the highly conserved and redundant Vitamin B12 uptake systems in P. aeruginosa. These systems efficiently transport cobalamin derivatives from the extracellular environment to the cytoplasm and are capable of transporting a range of cobalamin derivatives. We will develop optimized Vitamin B12-antibacterial conjugates that are programmed for optimal exposure and minimized toxicities from host cell uptake. In addition, we will leverage highly optimized, novel antibacterial drugs and leads whose barrier to development against Gram-negative bacteria is only cytoplasmic delivery as cargos. The successful delivery of this program will not only provide novel Gram-negative antibacterial agents poised for IND-enabling studies, but will also demonstrate the potential of active transport conjugate drug delivery approaches to transform antibacterial drug discovery.