Sandler Center for Drug Discovery, University of California, San Francisco, California, USA.
Antimicrob Agents Chemother. 2012 Nov;56(11):5450-7. doi: 10.1128/AAC.00643-12. Epub 2012 Aug 6.
Primary amebic meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living ameba Naegleria fowleri. The drug of choice in treating PAM is the antifungal antibiotic amphotericin B, but its use is associated with severe adverse effects. Moreover, few patients treated with amphotericin B have survived PAM. Therefore, fast-acting and efficient drugs are urgently needed for the treatment of PAM. To facilitate drug screening for this pathogen, an automated, high-throughput screening methodology was developed and validated for the closely related species Naegleria gruberi. Five kinase inhibitors and an NF-kappaB inhibitor were hits identified in primary screens of three compound libraries. Most importantly for a preclinical drug discovery pipeline, we identified corifungin, a water-soluble polyene macrolide with a higher activity against Naegleria than that of amphotericin B. Transmission electron microscopy of N. fowleri trophozoites incubated with different concentrations of corifungin showed disruption of cytoplasmic and plasma membranes and alterations in mitochondria, followed by complete lysis of amebae. In vivo efficacy of corifungin in a mouse model of PAM was confirmed by an absence of detectable amebae in the brain and 100% survival of mice for 17 days postinfection for a single daily intraperitoneal dose of 9 mg/kg of body weight given for 10 days. The same dose of amphotericin B did not reduce ameba growth, and mouse survival was compromised. Based on these results, the U.S. FDA has approved orphan drug status for corifungin for the treatment of PAM.
原发性阿米巴脑膜脑炎（PAM）是一种由自由生活的阿米巴 Naegleria fowleri 引起的快速致命感染。治疗 PAM 的首选药物是抗真菌抗生素两性霉素 B，但它的使用与严重的不良反应有关。此外，接受两性霉素 B 治疗的少数患者已存活下来 PAM。因此，迫切需要快速有效的药物来治疗 PAM。为了促进针对这种病原体的药物筛选，开发并验证了一种针对密切相关物种 Naegleria gruberi 的自动化高通量筛选方法。在三个化合物文库的初步筛选中，发现了五种激酶抑制剂和一种 NF-κB 抑制剂。最重要的是，对于临床前药物发现管道，我们发现了 corifungin，一种水溶性多烯大环内酯类化合物，对 Naegleria 的活性高于两性霉素 B。用不同浓度的 corifungin 孵育的 N. fowleri 滋养体的透射电子显微镜显示细胞质和质膜破裂，线粒体改变，随后阿米巴完全裂解。在 PAM 小鼠模型中，corifungin 的体内疗效通过在感染后 17 天内大脑中未检测到阿米巴和 100%的小鼠存活得到证实，每天腹腔内给予 9mg/kg 体重的 corifungin 10 天。相同剂量的两性霉素 B 不能减少阿米巴的生长，并且小鼠的生存受到影响。基于这些结果，美国 FDA 已批准 corifungin 作为治疗 PAM 的孤儿药。
