A Monoclonal Cocktail for CDI

描述(申请人提供)：艰难梭菌相关性疾病(CDI)是医院和疗养院患者发病率的重要原因，并日益被认为是死亡的重要原因。据估计，仅在美国，CDI的经济负担就高达10-30亿美元。该项目的总体目标是开发一种用于预防和/或治疗艰难梭菌感染的抗毒素HUMN单抗产品。由于特异性、稳定性、安全性和针对毒素的特异性(而不是对细菌的选择性压迫)，mAb产品是预防和治疗艰难梭菌引起的疾病的理想产品。抗体是FDA批准的唯一一类专门中和毒素的治疗药物。我们已经分离出一组识别艰难梭菌毒素的中和人类单抗(MAbs)。就其体外中和效力而言，这些单抗优于先前报道的处于临床开发中的单抗[1]。初步的体内试验表明，在仓鼠模型中的保护作用优于万古霉素。我们将在一个可扩展的生产系统中生产我们的每个人抗艰难梭菌毒素A和B(TcdA，TcdB)的单抗，该系统可以为治疗或预防适应症提供抗体。将在仓鼠模型中评估每一种单抗以及单抗的组合在预防和治疗艰难梭菌感染方面的有效性，以选择用于继续开发的主要单抗鸡尾酒。具体目标#1.在一种新的制造系统中，大量生产抗TcdA和抗TcdB的人源单抗，用于体外鉴定和动物试验。用含有人免疫球蛋白基因座的转基因小鼠(HuMab-Mouse(R))制备了人源性抗TcdA和抗TcdB单抗。三个抗TcdA和三个抗TcdB的单抗已经在MAPP的许可下开发出来。所有单抗都显示出强大的中和活性，随后已在可扩展的植物系统中生产。结合起来，这些单抗在仓鼠挑战模型中是有效的免疫保护剂。具体目的#2.评价单个单抗和体内单抗组合预防和治疗CDI的作用。在艰难梭菌感染的仓鼠模型中，将比较在特定目标#1中生产的单抗。首先将对抗TcdA单抗进行单独评估，以确定保护基线。仅观察到抗TcdA单独提供显著保护，而抗TcdB可延长抗TcdA保护的持续时间和有效性[1]。然后，将进一步测试最佳的抗TcdA mAb与每个抗TcdB mAb的组合，以确定mAb对的协同潜力。最佳单抗对将被挑选出来，用于临床前和临床方案的进一步开发，主要由SBIR第二阶段拨款资助。 公共卫生相关性：这项提案中的努力将有助于开发一种药物产品，用于预防和/或治疗艰难梭菌感染(CDI)，CDI是医院和疗养院严重致病和死亡的原因。在美国，CDI的经济成本保守地估计为每年10-30亿美元。最近，一种流行的艰难梭菌菌株的毒力和抗生素耐药性增加，这使得开发替代疗法变得更加紧迫。

DESCRIPTION (provided by applicant): Clostridium difficile associated disease (CDI) is an important cause of morbidity in hospital and nursing home patients, and is being increasingly recognized as an important cause of mortality. Estimates put the economic burden of CDI at 1-3 billion dollars in the U.S. alone. The overall goal of this project is to develop an anti-toxin humn monoclonal antibody product for prevention and/or treatment of C. difficile infection. Due to specificity, stability, safety, and the specific targeting of toxins (as opposed to selective pressre on the bacterium), a mAb product is ideal for prevention and treatment of the diseases caused by C. difficile. Antibodies are the only category of FDA-approved therapeutic that specifically neutralize toxins. We have isolated a panel of neutralizing human monoclonal antibodies (mAbs) that recognize the toxins of C. difficile. In terms of their neutralizing potency in vitro, these mAbs are superior to mAbs previously reported that are in clinical development [1]. Preliminary testing in vivo has demonstrated protection in the hamster model that was superior to vancomycin. We will produce each of our human mAbs against C. difficile toxins A and B (TcdA, TcdB) in a scalable production system that can provide antibodies for therapeutic or prophylactic indications. Each mAb, as well as the combination of mAbs, will be evaluated for effectiveness in preventing and treating C. difficile infection in the hamster model to select the lead mAb cocktail for continued development. Specific Aim #1. Produce quantities of each anti-TcdA and anti-TcdB human mAb for in vitro characterization and animal testing in a novel manufacturing system. Human anti-TcdA and anti-TcdB mAbs have been generated using transgenic mice containing human immunoglobulin loci (HuMab-Mouse(r)). Three anti-TcdA and three anti-TcdB mAbs have been developed under license by Mapp. The mAbs all exhibited potent neutralizing activity and have subsequently been produced in a scalable plant-based system. Combined, these mAbs are potent immunoprotectants in the hamster challenge model. Specific Aim #2. Evaluate individual mAbs and combinations of mAbs in vivo for prevention and treatment of CDI. MAbs produced in Specific Aim #1 will be compared in the hamster model of C. difficile infection. The anti-TcdA mAbs will first be evaluated individually to determine the baseline of protection. Only anti-TcdA has been observed to provide significant protection alone, whereas anti-TcdB may extend the duration and effectiveness of anti-TcdA protection [1]. The best anti- TcdA mAb will then be further tested in combination with each anti-TcdB mAb to determine the synergistic potential of mAb pairs. The best mAb pair will be selected for further development in pre-clinical and clinical protocols largely funded by a Phase II SBIR grant. PUBLIC HEALTH RELEVANCE: The efforts in this proposal will help in the development of a drug product for preventing and/or treating Clostridium difficile infection (CDI), a cause of significant morbidity and mortality in hospitals and nursing homes. The economic cost of CDI has been conservatively estimated at $1-3 billion per year in the U.S. The recent characterization of an epidemic C. difficile strain with increased virulence and antibiotic resistance has made the development of alternative therapies even more pressing.