Novel approaches to develop a treatment for cryptosporidiosis

描述（由申请方提供）：隐孢子虫病，由于肠道感染细胞内寄生虫隐孢子虫或隐孢子虫。在美国，人型痢疾是由水传播疾病引起的腹泻的主要原因，并且是发展中国家儿童感染性腹泻的主要原因。这种感染是慢性的，对免疫功能低下的患者来说往往是致命的，在艾滋病患者中，隐孢子虫病引起的慢性腹泻多达50%。不幸的是，硝唑尼特，唯一已知疗效的药物，对免疫功能正常的人的治疗效果仅为中等，对严重免疫功能低下的人的治疗效果与安慰剂相当。隐孢子虫病主要影响发展中国家的人们，并且从头药物开发的高成本是开发有效治疗的主要障碍。使用药物再利用方法来解决这一经济障碍，该项目的最终目标是开发一种有效的隐孢子虫病治疗方法。目标产品要求治疗安全，成本低，在小肠和胆道内相关浓度下对隐孢子虫具有选择性毒性，并且能够在缺乏有效宿主免疫力的情况下从患者体内消除寄生虫。为此，提供了初步数据，记录：1）一个强大的，基于细胞的，高通量筛选（HTS）试验的开发和验证; 2）FDA批准的药物与选择性抗隐孢子虫活性的鉴定;和3）体外试验，以比较不同的治疗方法，以消除C。从基于细胞的组织培养系统中分离小孢子。 目标1：所鉴定的抗隐孢子虫药物的能力导致消除隐孢子虫。将在体外测定微小孢子虫，然后在严重免疫受损小鼠中使用隐孢子虫病模型在体内测试药物先导物。协同药物组合有时具有杀菌抗微生物活性（即，杀死微生物而不仅仅是抑制微生物生长），尽管单独使用的每种药物具有静态活性，并且在某些情况下，药物组合能够成功治疗其中任一种药物单独使用无效的免疫功能低下的患者。因此，在目标2中，将进行组合药物筛选以鉴定当与硝唑尼特或初步筛选命中物一起使用时具有协同抗隐孢子虫活性的药物。作为概念证明，在亚抑制浓度的硝唑尼特存在下进行筛选，其产生五种批准的药物，当单独使用时没有抗隐孢子虫活性，其是强隐孢子虫。与低剂量硝唑尼特组合的小孢子生长抑制剂。有希望的药物组合的协同作用将通过棋盘测定来确认，并且最有希望的将如目的1中在体外和体内进行随访。这些特定目标的成功完成将导致确定至少一种FDA批准的药物或药物组合，治愈感染C.并且适合于在人类临床试验中测试。

DESCRIPTION (provided by applicant): Cryptosporidiosis, due to intestinal infection with the intracellular parasites Cryptosporidium parvum or C. hominis, is the leading cause of diarrhea resulting from waterborne outbreaks in the United States, and it is a major cause of pediatric infectious diarrhea in the developing world. The infection is chronic and often fatal for immunocompromised patients, and cryptosporidiosis causes as much as 50% of chronic diarrhea in AIDS patients. Unfortunately, nitazoxanide, the only drug with known efficacy, is only moderately effective for treatment of immunocompetent people, and it is equivalent to placebo in severely immunocompromised people. Cryptosporidiosis predominantly affects people in the developing world, and the high cost of de novo drug development is a major barrier to developing an effective treatment. Using a drug repurposing approach to address this economic barrier, the ultimate goal of this project is to develop an effective therapy for cryptosporidiosis The target product profile requires that the treatment be safe, low in cost, selectively toxic for Cryptosporidium at concentrations relevant within the small intestine and biliary tract, and capable of eliminating the parasite from patients in the absence of effective host immunity. Towards this end, preliminary data are presented documenting: 1) development and validation of a robust, cell-based, high-throughput screening (HTS) assay; 2) identification of FDA-approved drugs with selective anti-Cryptosporidium activity; and 3) an in vitro assay to compare the ability of different treatments to eliminate C. parvum from a cell-based tissue culture system. In aim 1, the abilities of the identified anti-Cryptosporidium drug leads to eliminate C. parvum will be determined in vitro, and then the drug leads will be tested in vivo using a model of cryptosporidiosis in severely immunocompromised mice. Synergistic drug combinations sometimes possess cidal antimicrobial activity (i.e., kill microbes rather than merely inhibit microbial growth) at achievable tissue concentrations despite static activity of each drug used alone, and, in some cases, drug combinations enable successful treatment of immunocompromised patients where either drug alone is ineffective. Therefore, in aim 2, combinatorial drug screens will be undertaken to identify drugs with synergistic anti-Cryptosporidium activity when used with nitazoxanide or the primary screening hits. As proof of concept, a screen was conducted in the presence of a sub-inhibitory concentration of nitazoxanide, which yielded five approved drugs with no anti-cryptosporidial activity when used alone that were strong C. parvum growth inhibitors in combination with low dose nitazoxanide. Synergy of promising drug combinations will be confirmed with checkerboard assays, and the most promising will be followed up in vitro and in vivo as in aim 1. Successful completion of these specific aims will result in identification of at least one FDA-approved drug or a combination of drugs that cures immunocompromised mice infected with C. parvum and is suitable for testing in human clinical trials.