Development of tolerogenic Factor VIII as immunotherapy to prevent inhibitor development in Hemophilia A

血友病A（HA）是由凝血因子VIII（FVIII）缺乏或功能障碍引起的出血性疾病，凝血因子VIII是重要的免疫调节因子。 凝血蛋白使用外源性FVIII的替代疗法是第一线疗法。然而，在这方面， 这种挽救生命的疗法的主要临床并发症是产生中和性抗FVIII抗体， 称为抑制剂，可消除FVIII的生物活性并增加出血相关风险 发病率和死亡率。抑制剂开发后的当前临床选择是昂贵的（>$700，000 每年每名患者），并且在一些患者中无效。因此，防止抑制剂的产生是成本有效的 但是目前没有安全有效的预防性治疗来避免抑制剂 发展本申请的总体目标是开发FVIII的致耐受性形式（TOLIP-FVIII）， 一种新的免疫疗法，以防止抑制剂的发展，在HA。该平台技术已开发 通过NHLBI对PI的支持，利用我们专有的溶血磷脂酰丝氨酸的致耐受性 （lysoPS）纳米颗粒。我们观察到，口服和静脉（IV）预先给予FVIII， 当用游离FVIII攻击时，lysoPS有效地减少了幼稚HA小鼠中抑制物的形成，表明 FVIII-lysoPS（TOLIP-FVIII）是FVIII的一种致耐受性形式，可以防止抑制剂的产生。为 在FVIII的前20次暴露期间，抑制物形成的风险要高得多，我们设想这种致耐受性 在高风险暴露期间，对于既往未经治疗的患者， （PUP），以持久地防止抑制剂的发展。此外，由于血浆存活率提高，这也可能是一种治疗方法。 所有HA患者的长效FVIII。在R61阶段，我们建议（1）制定持久免疫方案， 耐受性;（2）通过进行TOLIP-FVIII静脉给药的半衰期和止血功效测定， 在HA小鼠中的药代动力学和药效学研究和（3）研究iv施用的 小鼠和非人灵长类动物中的TOLIP-FVIII。这些SA提供了可衡量的里程碑， 持久耐受性、非劣效PK和止血疗效的最佳免疫/治疗方案，以及 可接受的安全性。作为R33的一部分，在第3年，我们将（1）研究这种TOLIP-FVIII方法是否 在HA小鼠中成功的方法可以转化为HA狗，和（2）表征这种致耐受性形式的PK/PD HA犬的FVIII。与国家灵长类动物中心建立了合作关系， TOLIP-FVIII在非人灵长类动物中的应用，并与北卡罗来纳州大学合作进行HA犬研究。我们 提出详细的项目管理计划，并与帝国探索研究所合作， 项目该项目的成功完成将导致一种新的免疫治疗平台，以防止抑制剂 发展HA，也可以奠定基础，创新的治疗方案，广泛的临床 潜在的，如预防其他治疗性蛋白质的免疫原性，改善基因治疗和CRISPR 治疗自身免疫性疾病和过敏症。

Hemophilia A (HA) is a bleeding disorder caused by deficiency or dysfunction of Factor VIII (FVIII), an important blood coagulation protein. The replacement therapy using exogenous FVIII is the first line of therapy. However, a major clinical complication of this life-saving therapy is the development of neutralizing anti-FVIII antibodies, referred to as inhibitors, that abrogates the biological activity of FVIII and increases the risk of bleeding related morbidity and mortality in HA patients. Current clinical options after inhibitor development are costly (>$700,000 per patient annually) and in some patients, ineffective. Thus, prevention of inhibitor development is cost-effective in terms of patient care but there are no safe and effective preventive therapy currently available to avoid inhibitor development. The overall objective of this application is to develop a tolerogenic form of FVIII (TOLIP-FVIII) as a novel immunotherapy to prevent inhibitor development in HA. This platform technology has been developed with NHLBI support to PI that harnesses the tolerogenic property of our proprietary lysophosphatidylserine (lysoPS) nanoparticle. We observed that an oral and intravenous (IV) pre-administration of FVIII associated with lysoPS effectively reduced inhibitor development in naïve HA mice when challenged with free FVIII, suggesting that FVIII-lysoPS (TOLIP-FVIII) is a tolerogenic form of FVIII that could prevent inhibitor development. As the risk of inhibitor development is much higher during the first 20 exposures of FVIII, we envision this tolerogenic form as beginner replacement therapy during high-risk exposure period, for previously untreated patients (PUPs), to durably prevent inhibitor development. Further, due to improved plasma survival, this could also be a longer acting FVIII for all HA patients. In R61 phase, we propose to (1) develop immunization protocol for durable tolerance; (2) determine the half-life and hemostatic efficacy of IV administered TOLIP-FVIII by conducting pharmacokinetic and pharmacodynamic studies in HA mice and (3) to investigate the toxicity of iv administered TOLIP-FVIII in mice and in non-human primates. These SAs present measurable milestones, identification of optimal immunization/treatment protocol for durable tolerance, non-inferior PK and hemostatic efficacy and acceptable safety profile. As part of R33, in year 3, we will (1) investigate whether this TOLIP-FVIII approach that is successful in HA mice can be translated to HA dogs and (2) characterize PK/PD of this tolerogenic form of FVIII in HA dogs. Collaborations have been established with National Primate Center to investigate toxicity of TOLIP-FVIII in non-human primates and with the University of North Carolina to conduct HA dog studies. We propose a detailed project management plan and partnered with Empire Discovery Institute for R33 phase of the project. Successful completion of the project will lead to a novel immunotherapy platform to prevent inhibitor development in HA and could also lay the foundation for innovative therapeutic options with broad clinical potential, such as prevention of immunogenicity of other therapeutic proteins, improve gene therapy and CRISPR outcomes, and treat autoimmune conditions and allergies.