Clinical trial of AAV8-mediated FVIII gene transfer for hemophilia A

摘要 我们提出了一个开放标签，剂量递增，I/II期研究，其中单剂量的新的 重组AAV载体AAV 2/8 HLP FVIII-V3 co将被施用到患者的外周静脉中。 重度血友病A成人受试者。我们的前提是，这将是一个安全有效的 限制这些患者出血倾向的方法。血友病A（HA）是一种X-连锁 一种由凝血因子VIII（FVIII）基因缺陷引起的隐性出血性疾病。FVIII编码 一种糖蛋白原辅因子，当被凝血酶激活时，与凝血因子IXa相互作用 级联，导致凝块形成。临床上，该病的特点是频繁自发性 出血，可能危及生命。我们的肝脏靶向治疗方法有几个新颖的方面， AAV介导的FVIII基因转移，包括1）符合AAV大小限制的独特FVIII cDNA 并介导全功能FVIII蛋白的合成，2）提高效率的表达盒， 和3）重组AAV载体生产的改进方法。我们 在鼠模型和恒河猴中的广泛研究表明，AAV 2/8 HLP FVIII-V3 co载体 在这些动物中安全地确定FVIII的治疗水平。此外，我们现在拥有独特的 成功开展肝脏靶向、AAV介导的FIX基因I/II期临床试验的经验 这为我们设计AAV介导的FVIII基因转移提供了新的见解 审判我们建议测试三个剂量水平：6x 1011、2x 1012和6x 1012 vg/kg。的主要目的 本研究旨在评估该载体全身给药的安全性，而次要目的是： 1)确定实现FVIII稳定表达所需的载体颗粒剂量≥正常值的5%; 2） 探讨对生活质量、情绪健康和神经认知功能的影响; 3）描述 对FVIII转基因产物和AAV衣壳蛋白的免疫应答和4）评估病毒脱落 变成各种体液招募仅限于确诊的成人（≥18岁） 由FVIII基因突变引起的重度HA与抑制剂的高发生率无关 阵此外，受试者必须接受≥50天的FVIII蛋白治疗暴露 浓缩而不产生抑制剂。将根据安全性（主要）进行剂量递增 和功效（次要）标准。免疫抑制剂将不常规给予接受 最低剂量的载体;相反，仅适用于发生ALT升高>1.5倍的低剂量患者 基线。然而，根据我们的AAV 2/8 FIX经验，中等和高剂量组的所有患者均接受了治疗。 从第6-13周，组群将接受预防性类固醇。停止规则包括：1） 在给定剂量水平下，1例患者发生IV级或V级毒性，或2例患者发生III级毒性，或 2)1例患者出现FVIII中和抗体。

Abstract We propose an open label, dose-escalation, phase I/II study in which a single dose of the novel recombinant AAV vector, AAV2/8 HLP FVIII-V3co, will be administered into a peripheral vein of adult subjects with severe hemophilia A . Our premise is that this will be a safe and efficacious approach for limiting the bleeding propensity of these patients . Hemophilia A (HA) is an X-linked recessive bleeding disorder that results from a defect in the factor VIII (FVIII) gene. FVIII encodes a glycoprotein procofactor which, when activated by thrombin, interacts with factor IXa in the coagulation cascade, leading to clot formation. Clinically, the disease is characterized by frequent spontaneous bleeding, which can be life-threatening. There are several novel aspects to our approach to liver-targeted AAV-mediated FVIII gene transfer, including 1) a unique FVIII cDNA that meets the size constraints of AAV and mediates synthesis of fully functional FVIII protein, 2) an expression cassette that improves the efficiency of FVIII expression and secretion and 3) an improved method of recombinant AAV vector production. Our extensive studies in murine models and rhesus macaques have shown that AAV2/8 HLP FVIII-V3co vector safely establishes therapeutic levels of FVIII in these animals. In addition, we now have the unique experience of having conducted a successful phase I/II clinical trial of liver-targeted, AAV-mediated FIX gene transfer for hemophilia B that has provided new insights to the design of our AAV-mediated FVIII gene transfer trial. We propose to test three dose levels: 6x1011, 2x1012 and 6x1012 vg/kg. The primary objective of the study is to assess the safety of systemic administration of this vector while the secondary objectives are: 1) to determine the dose of vector particles required to achieve stable expression of FVIII ≥5% of normal; 2) to explore the impact on quality of life, emotional health and neurocognitive function; 3) to describe the immune responses to the FVIII transgene product and AAV capsid proteins and 4) to assess viral shedding into various body fluids. Recruitment will be limited to adults (≥18 years of age) with a confirmed diagnosis of severe HA caused by a mutation in the FVIII gene not associated with a high incidence of inhibitor formation. In addition, participants must have had ≥50 exposure days of treatment with FVIII protein concentrate without having developed an inhibitor. Dose escalation will proceed based on safety (primary) and efficacy (secondary) criteria. Immunosuppression will not be given routinely to patients receiving the lowest dose of vector; rather, only for those low dose patients who develop ALT elevation >1.5-times baseline. However, based on our AAV2/8 FIX experience, all patients in the intermediate and high dose cohorts will receive prophylactic steroids from weeks 6-13. Stopping rules are in place which include: 1) the occurrence of Grade IV or V toxicity in one patient or Grade III toxicity in two patients at a given dose level or 2) the development of neutralizing antibodies to FVIII in one patient.