Preclinical evaluation of rAAV encoding a novel highly expressed Factor VIII molecule for haemophilia A gene therapy

在拟议的研究中，我们希望测试一种新的方法，称为基因疗法，用于治疗血友病A患者。这种在没有创伤的情况下发生危及生命的出血的遗传性疾病是由称为因子FVIII（FVIII）的凝血蛋白的缺失或缺陷引起的，所述凝血蛋白是由于FVIIIX基因突变而产生的。因此，我们的基因治疗方法的目标是通过转移到病人身上来治疗疾病。在患者的肝脏中，FVIII基因的正常拷贝，以便患者可以持续产生正常的FVIII蛋白？自己的细胞。为此，我们开发了一种基于腺相关病毒的新型载体（rAAV 8-HLP-codop-hFVIII），其在将正常FVIII基因转移到肝脏（其天然合成位点）方面是高效的。重要的是，在病毒来源的基因转移载体中，AAV具有最好的安全性。在鼠模型中，我们始终实现了人FVIII的长期表达，其水平足以在单次注射rAAV 8-HLP-codop-hFVIII后预防血友病A患者中自发性危及生命的出血。在对甲型血友病患者评价这种新载体之前，我们必须使用高质量的临床级载体而不是研究级载体，按照监管机构要求的严格标准确定其安全性和有效性。因此，本申请被设计为产生足够量的临床级rAAV 8-HLP-codop-hFVIII载体，然后在与人类相关的背景下仔细和严格地评估其安全性和有效性。本研究的结果将用于支持在重度血友病A患者中启动临床试验。我们的方法的成功可能会对多种危及生命的遗传性疾病产生显着影响，包括α-1抗胰蛋白酶缺乏症，溶酶体贮积症和尿素循环障碍。

In the proposed study we wish to test a new approach called gene therapy for the treatment of patients with haemophilia A. This inherited disorder in which life threatening bleeding occurs without trauma results from an absence or defect of a blood clotting protein called Factor FVIII (FVIII) that arises due to mutations in the FVIIIX gene. The goal of our gene therapy approach, therefore, is to treat the disease by transferring to the patient?s liver, a normal copy of the FVIII gene so that normal FVIII protein can be continuously produced by the patient?s own cells. To this end we have developed a novel vector based on adeno-associated virus (rAAV8-HLP-codop-hFVIII) which is highly efficient at transferring the normal FVIII gene to the liver, its natural site of synthesis. Importantly, AAV has the best safety profile among gene transfer vectors of viral origin. In murine models we have consistently achieved long-term expression of human FVIII at levels that would be sufficient to prevent spontaneous life threatening bleeding in haemophilia A patients following a single injection of rAAV8-HLP-codop-hFVIII. Prior to evaluating this new vector in patients with haemophilia A, we have to establish its safety and efficacy to the rigorous standards required by the regulators using high quality clinical grade vector as opposed to research grade vector. This application is therefore designed to generate sufficient quantities of clinical grade rAAV8-HLP-codop-hFVIII vector and then carefully and critically evaluate its safety and efficacy in a context relevant to humans. The results of this study will be used to support the initiation of a clinical trial in patients with severe haemophilia A. Success with our approach could significantly impact on a wide variety of life threatening genetic disorders including alpha-1 antitrypsin deficiency, lysosomal storage and urea cycle disorders.