Development and pharmacology of novel lipidic rAHF

描述(由申请人提供)：针对治疗蛋白的抗体反应的发展，如因子VIII(FVIII)，是一个主要的临床并发症，损害了基于蛋白质的疗法的安全性和有效性。我们的目标是通过开发非免疫原性形式的分子来提高蛋白质的治疗效果。FVIII是一种多结构域蛋白，在凝血级联反应中起关键作用。FVIII的缺乏和功能障碍会导致血友病A，一种出血性疾病。给予重组FVIII是甲型血友病(HA)患者的一线治疗方法。这种替代疗法的安全性和有效性因出现抑制性抗体反应而严重受损，这种抗体反应发生在接受FVIII治疗的15%-30%的HA患者中。我们已经证实，通过将蛋白质与磷脂酰丝氨酸(FVIII-PS)或磷脂酰肌醇(FVIII-PI)络合，对FVIII的抗体反应显著降低。为了利用这一新的发现来开发更有效的FVIII形式，并确定这种脂质修饰如何与其他治疗性蛋白一起使用，必须确定降低免疫原性的机制。因此，在目标1中，我们建议确定抗体反应的降低是否由于脂类复合体改变抗原处理和蛋白质呈递的能力，从而主动诱导HA小鼠的免疫耐受。或者，我们将确定它是否是由于免疫原性决定簇的脂质屏蔽导致的被动过程。这些研究将揭示观察到的降低的抗体反应的稳健性、特异性、安全性和持久性，并将确定脂类复合体降低或消除已经建立的抗FVIII抗体反应的程度。因为给药的频率增加了免疫原性反应，所以减少给药频率的长效脂质-FVIII复合体是有用的。在目标2中，将研究脂头基团和聚乙二醇化修饰对FVIII的药代动力学的影响。PK特性，如循环半衰期、平均滞留时间和静脉或sc注射后FVIII的暴露，将通过量化和比较脂类FVIII制剂与单独使用FVIII观察到的FVIII水平来确定。FVIII的止血效果是具有临床意义的关键终点。目的3将通过体内标准化的尾静脉横断试验，确定脂质络合如何影响脂质络合FVIII的药效学和治疗效果。在SA 4中，FVIII-脂质复合体降低免疫原性和PK的翻译效用将在灵长类动物模型猕猴中进行测试。这些研究有望阐明脂类FVIII复合体降低免疫原性、改善动物模型的药代动力学和治疗效果的机制，以便将这一观察扩展到临床试验，并应用于其他治疗性蛋白的设计、配方和给药，以克服对其临床应用产生负面影响的问题。

DESCRIPTION (provided by applicant): The development of antibody responses against therapeutic proteins such as Factor VIII (FVIII) is a major clinical complication that compromises the safety and efficacy of protein based therapeutics. Our goal is to improve upon the therapeutic efficacy of proteins by developing non-immunogenic forms of the molecules. FVIII is a multi-domain protein that plays a critical role in blood coagulation cascade. The deficiency and dysfunction of FVIII causes Hemophilia A, a bleeding disorder. Administration of recombinant FVIII is the first line of therapy for Hemophilia A (HA) patients. The safety and efficacy of this replacement therapy is severely compromised by the development of inhibitory antibody responses that occur in 15-30% of HA patients treated with FVIII. We have established that the antibody response to FVIII is reduced significantly by complexing the protein with phosphatidylserine (FVIII-PS) or phosphatidylinositol (FVIII-PI). To exploit this novel finding for developing a more therapeutically effective form of FVIII, and to determine how such lipid modifications may be used with other therapeutic proteins, it is imperative to determine the mechanisms by which the reduction of immunogenicity is achieved. Therefore, in Aim 1 we propose to establish whether the decrease in the antibody response is due to the lipid complexes' ability to alter antigen processing and presentation of the protein, resulting in active induction of immunological tolerance in HA mice. Alternatively we will determine whether it is due to a passive process that results from lipid shielding of immunogenic determinants. These studies will reveal the robustness, specificity, safety and durability of the reduced antibody responses observed, and will establish the degree to which the lipid complexes reduce or eliminate an already-established anti-FVIII antibody response. Because the frequency of administration increases immunogenic response, long acting lipid-FVIII complexes that reduce the frequency of administration are useful. In Aim 2, the effect of lipid headgroup and PEG modification upon the pharmacokinetics (PK) of FVIII will be investigated. PK properties, such as circulation half-life, mean residence time and exposure of FVIII following iv or sc injection, will be established by quantifying and comparing the FVIII levels achieved with lipidic FVIII formulations to those observed with FVIII alone. The haemostatic efficacy of FVIII is the key endpoint of clinical significance. Aim 3 will establish how lipid complexation affects the pharmacodynamics and therapeutic efficacy of the lipid- complexed FVIII by using an in vivo standardized tail vein transection assay. In SA 4, the translational utility of reduction in immunogenicity and PK of FVIII-lipid complex will be tested in a primate model, Macaque mulatta. These studies are expected to elucidate the mechanistic basis by which lipidic FVIII complexes decrease immunogenicity, and improve pharmacokinetics and therapeutic efficacy in animal models, so that this observation may be extended to clinical trial, and applied also to the design, formulation and delivery of other therapeutic proteins, so as to overcome issues that negatively impact their clinical use.