PFOR inhibitor amixicile for treatment of drug resistant parasites and bacteria

描述（由申请人提供）：丙酮酸：铁氧还蛋白氧化还原酶（PFOR）是所有严格厌氧细菌、厌氧人类寄生虫和epsilon变形杆菌（幽门螺杆菌和弯曲杆菌）中心代谢的必需酶。Amixicile是我们团队开发的一种一流的氨基硝基噻唑丙胺抗生素，专门抑制PFOR和相关酶，其中机制酶学和模型研究表明，化学抑制机制涉及活化的焦磷酸硫胺素（TPP，维生素B1的衍生物）辅助因子的去质子化，从而使PFOR催化循环失活1。意义：由于维生素如TPP的化学变化被认为是致命的，这种机制似乎可以避免基于突变的耐药性。重要的是，没有观察到艰难梭菌临床分离株或幽门螺杆菌体外突变体生成方法对氨苄西林的耐药性。不具有氧化还原活性，不具有诱变性，也不是硝基还原酶的底物；与fda批准的母体药物nitazoxanide （NTZ）相比，具有更高的靶向选择性、生物利用度和更低的毒性。Amixicile被开发用于治疗艰难梭菌感染（CDI），在小鼠CDI模型中，被认为可以预测人类疗效，Amixicile在第5天表现出优于NTZ和与标准疗法（非达霉素和万古霉素）等效的优势，第14天优于两种药物，CDI没有复发。氨甲氧嘧啶不会损害有益的益生菌群。Amixicile已经完成了临床前评估，具有出色的药理学指标（ADME、毒理学和PK），并正在进行1期临床试验。本研究将验证PFOR药物靶点，评估amixicile对细小隐孢子虫、贾第鞭毛虫、阴道毛滴虫、溶组织内阿米巴和幽门螺杆菌的治疗效果，以满足新的干预措施的可行性或使用目标，并为先导物优化和筛选不断发展

DESCRIPTION (provided by applicant): Pyruvate: ferredoxin oxidoreductase (PFOR) is an essential enzyme of central metabolism in all strictly anaerobic bacteria, anaerobic human parasites and in epsilon proteobacteria (Helicobacter and Campylobacter). Amixicile, a first-in-class amino-nitrothiazole propylamine antibiotic developed by our team, specifically inhibits PFOR and related enzymes, where both mechanistic enzymology and modeling studies suggest a chemical inhibition mechanism involving deprotonation of the activated thiamine pyrophosphate (TPP, a derivative of vitamin B1) cofactor, thus inactivating the PFOR catalytic cycle1. Significance: This mechanism appears to escape mutation based drug resistance as chemical changes to vitamins like TPP are believed to be lethal. Importantly, resistance to amixicile has not been observed with Clostridium difficile clinical isolates or through in vitro mutant generation methods with H. pylori. Amixicile is not redox-active, mutagenic or a substrate of nitroreductases; and demonstrates greater target selectivity, bioavailability and lower toxicity compared to parent FDA-approved drug nitazoxanide (NTZ). Amixicile was developed to treat C. difficile infections (CDI) and in a mouse CDI model, considered predictive of human efficacy, amixicile showed superiority to NTZ and equivalence to standard therapies (fidaxomicin and vancomycin) at 5 days and superiority over both drugs by day 14 with no recurrence of CDI. Amixicile does not harm beneficial probiotic microflora. Amixicile has completed preclinical evaluation with excellent pharmacological metrics (ADME, toxicology and PK) and is on track for phase 1 clinical trials. The proposed studies will validate the PFOR drug target and assess therapeutic efficacy of amixicile against Cryptosporidium parvum, Giardia lamblia, Trichomonas vaginalis, Entamoeba histolytica and Helicobacter pylori to meet the "feasibility or use in new interventions objective, and for lead optimization and screens to evolve more potent analogues". We have assembled a collaborative team of experts in medicinal chemistry, parasitology, microbial biochemistry and animal models and have developed a pipeline approach to fast track second generation leads as outlined below in the specific aims for R21 and R33 enabling studies. The R21 phase of these studies will include: Aim 1 to evaluate amixicile in mouse models of infection for Cryptosporidium parvum, Giardia lamblia, Entamoeba histolytica, and Helicobacter pylori; Aim 2 performs a medicinal chemistry directed lead optimization of amixicile by structure activity relationships and begins exploring coupling of amino nitro-thiazole to existing antibiotics based on the success of creating ciprothiazole from ciprofloxacin and aim 3 will complete the R33 portion of the studies by in vitro and in vivo testin of developed leads from amixicile and novel multi- target therapeutics created in Aim 2. Efficacy studies and preliminary PK studies with new analogues will be prioritized for further preclinical evaluation. Our strategy of developing new therapeutics that target vitamin cofactors and multiple drug targets is designed to overcome typical pathways of drug resistance.