Clinical trial of self complementary AAV8-mediated gene transfer for hemophilia B

我们提出了一个开放标签，剂量递增，I/II期研究，其中单剂量的新的自我， 将互补AAV载体scAAV 2/8 LP 1 hFIXco施用到成年受试者的外周静脉中 患有严重的血友病B血友病B（HB）是一种X连锁隐性出血性疾病， 因子IX（FIX）基因缺陷，该基因编码对适当的纤维蛋白凝块形成至关重要的丝氨酸蛋白酶。 在临床上，该病的特征是频繁的自发性出血，最常见的部位是 关节和软组织，但也可能发生在大脑中，并可能危及生命。我们广泛 在鼠模型和恒河猴中的研究表明，scAAV 2/8 LP 1 hFIXco载体建立了 与先前研究中评价的载体相比，这些动物中相对低剂量的FIX治疗水平 临床试验这项研究与以前使用AAV载体的HB临床试验在三个重要方面不同。 首先，将使用AAV 8假型化载体代替AAV 2，主要是因为AAV 8假型化载体显著较低的表达量。 在人类中对该AAV血清型的预先存在的免疫力的流行。第二个区别是使用 含有自身互补基因组的载体，由于其快速形成稳定， 在靶组织中具有转录活性的双链线性分子，提供了独特的机会， 介导有效的治疗基因转移的载体可能在较低的剂量。最后因为 无论施用途径如何，载体的生物分布主要是肝脏，scAAV颗粒 将通过外周静脉给药我们建议测试三个剂量水平：2x 1010、6x 1010和2x 1011 每公斤体重的载体基因组。本研究的主要目的是评估 而次要目的是1）确定载体的剂量 颗粒需要达到稳定表达的hFIX在或高于正常的3%; 2）描述免疫 对hFIX转基因产物和AAV衣壳蛋白的应答和3）获得病毒脱落到各种细胞中， 体液招募将限于成年人（大于或等于18岁）， hFIX基因错义突变导致的严重HB诊断。将观察患者， 在载体施用后至少42天，然后招募下一个患者。可将剂量继续递增 基于安全性（主要）和有效性（次要）标准。不常规给予免疫抑制; 相反，只有当患者发生急性，显著的转氨酶升高（ALT或胆红素> 10倍正常值）或持续性 （>16周）ALT或胆红素升高。发生以下任何一种情况将导致立即 暂停试验：1）1例患者发生IV级毒性或2例患者发生III级毒性 在给定的剂量水平下。2)基因转移后FIX中和抗体的产生， 话题吧5)患者在基因转移后的任何时间点死亡，可能、很可能或肯定相关 给研究代理人。目前血友病B治疗的不足激发了人们对替代疗法的兴趣。 治疗方法，包括基因转移。成功的AAV介导的基因转移 对于血友病B提供了有效的终身预防出血的潜力， 这种疾病的患者的并发症。此外，从这方面获得的信息 这项研究在计划未来使用AAV载体的其他策略中将是重要的，其中 其它影响肝脏的疾病，如溶酶体贮积症和尿素循环障碍， 是有针对性的。

We propose an open label, dose-escalation, phase I/II study in which a single dose of the novel self- complementary AAV vector, scAAV2/8 LP1 hFIXco, will be administered into a peripheral vein of adult subjects with severe hemophilia B. Hemophilia B (HB) is an X-linked recessive bleeding disorder that results from a defect in the factor IX (FIX) gene which encodes a serine protease critical for appropriate fibrin clot formation. Clinically the disease is characterized by frequent spontaneous bleeding, most commonly into such sites as joints and soft tissues, but which can also occur in the brain and potentially be life threatening. Our extensive studies in murine models and rhesus macaques have shown that scAAV2/8 LP1 hFIXco vector establishes therapeutic levels of FIX at relatively low doses in these animals, compared to vectors evaluated in previous clinical trials. This study differs from previous HB clinical trials with AAV vectors in three important aspects. Firstly, an AAV8 pseudotyped vector will be used instead of AAV2, primarily because of the substantially lower prevalence of pre-existing immunity to this AAV serotype in humans. The second difference relates to the use of a vector containing a self-complementary genome which, because of its ability to rapidly form stable, transcriptionally active, double stranded linear molecules in target tissues, offers the unique opportunity to mediate efficient therapeutic gene transfer potentially at lower doses of vector. Finally, because the biodistribution of vector is predominantly to the liver regardless of the route of administration, scAAV particles will be administered via a peripheral vein. We propose to test three dose levels: 2x1010, 6x1010 and 2x1011 vector genomes per kilogram body weight. 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 hFIX at or above 3% of normal; 2) to describe the immune responses to the hFIX transgene product and AAV capsid proteins and 3) to access viral shedding into various body fluids. Recruitment will be limited to adults (greater than or equal to 18 years of age) with a confirmed diagnosis of severe HB resulting from a missense mutation in the hFIX gene. Patients will be observed for at least 42 days following vector administration before enrollment of the next patient. Dose escalation will proceed based on safety (primary) and efficacy (secondary) criteria. Immunosupression will not be given routinely; rather, only if a patient develops acute, significant transaminitis (ALT or bilirubin >10X normal) or persistent (>16 weeks) ALT or bilirubin elevation. The occurrence of any of the following will result in immediate suspension of the trial: 1) The occurrence of Grade IV toxicity in one patient or Grade III toxicity in two patients at a given dose level. 2) The development of neutralizing antibodies to FIX following gene transfer in one subject. 5) Death of a patient at any time point after gene transfer that is possibly, probably, or definitely related to the study agent. The inadequacies of current therapy for hemophilia B have fuelled interest in alternative treatment approaches, including gene transfer. Successful AAV-mediated gene transfer for hemophilia B offers the potential of effective lifetime prevention of bleeding and its complications for patients with this disorder. In addition, the information gained from this study will be important in planning additional future strategies with AAV vectors in which other disorders affecting the liver, such as lysosomal storage and urea cycle disorders, are targeted.