Novel Therapy for Preeclampsia

描述（由申请人提供）：先兆子痫（PE）是一种严重的妊娠并发症，表现为高血压、蛋白尿和水肿，有时伴有脑病、癫痫发作和肝功能衰竭。PE使5%至10%的妊娠并发症，并且是全球孕产妇和胎儿发病率和死亡率的主要原因。然而，这种疾病的有效治疗方法并不存在。目前尚无明确的治疗方法，但可通过抗高血压药物、镁和类固醇等姑息性措施以及早期分娩改善结局。内源性“地高辛样”因子（EDLF）的循环水平升高是在20世纪80年代首次发现的，EDLF是一种与抗地高辛抗体交叉反应并抑制Na+/K+ ATP酶（NKA）的未知物质。大量文献支持这一假设，即EDLF水平的增加可能是高血压发病机制中的致病因素。近年来，内源性强心类固醇（CTS）--海蟾毒配基（MBG）已被鉴定为EDLF。妊娠合并PE患者血浆MBG水平升高，提示MBG可能参与PE的病理生理过程。Digibind（GlaxoSmithKline）是一种市售抗地高辛绵羊多克隆抗体，获批用于治疗地高辛过量。Digibind与MBG和其他CTS发生交叉反应。Digibind可降低PE啮齿动物模型的血压。Digibind已被证明可逆转PE患者红细胞中NKA的抑制作用。除了这一广泛的临床前文献外，在8例人类PE病例中获得了令人鼓舞的结果，无不良反应。Digibind在51例重度PE患者中的临床试验显示，与安慰剂相比，肾功能显著改善，无不良反应。本项目的总体目标是开发和表征人抗MBG单克隆抗体（humAb）作为PE的创新治疗。地高辛的小鼠单克隆抗体（mAb）已作为模型系统进行了广泛研究，已知与所有其他已检测的CTS以及相关类固醇交叉反应。在第一阶段，我们将把这种鼠抗地高辛mAb改造成对MBG具有高特异性的人mAb。亲和力成熟与已知修饰地高辛结合位点特异性的特定氨基酸的靶向体外诱变组合将产生多克隆。克隆将通过其对MBG的亲和力和特异性进行等级排序。最后，我们将在NKA测定中评价功能。生产具有纳摩尔Kd、对MBG的高特异性和逆转MBG对NKA抑制的能力的humAb将值得提交2期申请。II期工作将集中于获得提交IND所需的临床前数据。将进行药代动力学和毒性研究以及证明疗效的动物研究。 公共卫生相关性：先兆子痫（PE）是一种妊娠并发症，影响5-10%的妊娠，可能危及生命。PE患者给予支持性治疗，如抗高血压药和类固醇。除分娩外，没有具体有效的治疗方法。最近，洋地黄样因子，海蟾毒配基（MBG）被认为是PE的致病因子。抗地高辛绵羊多克隆抗体Digibind也与MBG反应。Digibind在临床试验中对PE有效。我们将开发一种新的人单克隆抗体，其特异性高于Digibind。这种创新的治疗性humAb将成为首个有效治疗PE的药物。

DESCRIPTION (provided by applicant): Preeclampsia (PE) is a serious complication of pregnancy manifested by high blood pressure, proteinuria, and edema, sometimes with encephalopathy, seizures, and hepatic failure. PE complicates from 5 to 10% of pregnancies, and is a major cause of maternal and fetal morbidity and mortality worldwide. Nevertheless, an effective therapy for this disorder does not exist. There is no known specific treatment, although palliative measures such as antihypertensive drugs, magnesium, and steroids, and early delivery improve outcomes. Elevation in the circulating level of an endogenous "digoxin-like" factor (EDLF), an unknown substance that cross reacts with anti-digoxin antibodies and inhibits the Na+/K+ ATPase (NKA) was first noted in the 1980s. An extensive literature supports the hypothesis that increased levels of EDLF may be a causative factor in the pathogenesis of hypertension. Recently, marinobufagenin (MBG), an endogenous cardiotonic steroid (CTS), has been identified as the EDLF. Plasma MBG is elevated in pregnancy complicated by PE, suggesting it might play a role in the pathophysiology of PE. Digibind (GlaxoSmithKline) is a commercially available anti-digoxin sheep polyclonal antibody approved for the treatment of digoxin overdose. Digibind cross-reacts with MBG and other CTS. Digibind lowers blood pressure in rodent models of PE. Digibind has been shown to reverse inhibition of the NKA in erythrocytes from patients with PE. In addition to this extensive pre-clinical literature, encouraging results with no adverse effects were obtained in 8 human cases of PE. A clinical trial of Digibind in 51 patients with severe PE showed significant improvement in renal function relative to placebo, with no adverse effects. The overall goal of this project is to develop and characterize a human anti-MBG monoclonal antibody (humAb) as an innovative treatment for PE. A mouse monoclonal antibody (mAb) to digoxin has been extensively studied as a model system and is known to cross-react with all other CTS that have been tested, as well as related steroids. In phase I, we will engineer this murine anti-digoxin mAb into a human mAb with high specificity for MBG. Affinity maturation, in combination with targeted in vitro mutagenesis of specific amino acids known to modify specificity of the binding site for digoxin, will yield multipe clones. Clones will be rank ordered by their affinity and specificity for MBG. Finally, we will evaluate function in an NKA assay. Production of a humAb with a nanomolar Kd, high specificity for MBG, and ability to reverse MBG inhibition of the NKA, will merit submission of a phase 2 application. Phase II work will focus on obtaining the preclinical data necessary for submission of an IND. Pharmacokinetics and toxicity studies, as well as animal studies to demonstrate efficacy, will be performed. PUBLIC HEALTH RELEVANCE: Preeclampsia (PE) is a complication of pregnancy that affects 5-10% of pregnancies and can be life- threatening. PE patients are given supportive therapy, such as anti-hypertensives and steroids. No specific and effective therapy, other than delivery, exists. Recently, a digitalis-like factor, marinobufagenin (MBG) has been implicated as a causative factor in PE. An anti-digoxin sheep polyclonal antibody, Digibind, also reacts with MBG. Digibind was effective for PE in a clinical trial. We will develop a novel human monoclonal antibody with higher specificity than Digibind for MBG. This innovative therapeutic humAb will be the first effective treatment of PE.