Bioengineered factor VIII gene therapy for hemophilia A

描述（由申请人提供）：本提案的总体目标是进行后期临床前研究，以支持血友病A造血干细胞移植基因治疗的初步临床试验。在最近的一系列研究中，我们已经表明，基因工程造血干细胞的移植可以恢复因子VIII（fVIII）的活性，在血友病A小鼠的治疗水平，人造血干细胞很容易与重组慢病毒编码基因工程fVIII转基因转导。迄今为止，我们是唯一一个使用常规临床实践中的非清髓性移植方案在血友病A小鼠中获得持续治疗性fVIII表达水平的组。我们的基因治疗方法使用生物工程fVIII转基因（称为ET-3），其在造血干细胞转导效率（1-5%）下实现正常fVIII活性水平（1单位/ml），这是目前在人类基因治疗临床试验中实现的。我们已经使用ET-3产生了大量的临床前数据，证明了用编码ET-3的慢病毒载体基因工程改造的造血干细胞，加上非清髓性移植方案，可用于治疗血友病A。我们现在建议首先与FDA进行IND前会议，以指导ET-3的最终临床前测试。因此，我们的后期测试将基于FDA指南。其次，我们将使用编码ET-3的临床级（GMP）慢病毒载体生成我们的最终临床前数据集，这将专门测试临床产品的安全性和有效性。预计将提交后续II期项目，以支持实际临床试验。有四个组织为实现这些目标结成了伙伴关系，其中包括：i）Expression Therapeutics，LLC，一家基于高表达fVIII技术成立的生物技术公司，ii）Emory大学，高表达fVIII技术的概念和概念证明发生在那里，iii）亚特兰大儿童保健，Emory大学基因治疗计划的财政支持者和Expression Therapeutics，LLC的投资者，和iv）Lentigen Corporation，一家致力于慢病毒载体的成功临床应用的公司，并且是最大的慢病毒载体知识产权组合的保持器持有者。Lentigen将产生 临床级重组慢病毒载体，将用于包括临床试验在内的拟定研究。 公共卫生相关性：凝血因子VIII表达不足导致出血性疾病血友病A。目前对这种疾病的治疗包括血浆衍生或重组因子VIII的困难、长期、静脉输注以恢复循环因子VIII活性水平，并且由于产品成本高和可用性有限，目前提供给不到三分之一的所有血友病A患者。基因疗法为这种使人衰弱的疾病提供了一种潜在的治疗方法，在世界许多地方，这种疾病是致命的。我们已经证明，骨髓细胞移植基因修饰表达工程因子VIII蛋白是一种可行的治疗血友病A。在目前的申请中，我们建议进行后期临床前试验，以支持批准首次用于人类临床的基因治疗 审判

DESCRIPTION (provided by applicant): The overall goal of this proposal is to conduct late-stage preclinical studies to support a pilot clinical trial of hematopoietic stem cell transplantaton gene therapy for hemophilia A. In a series of recent studies, we have shown that the transplantation of genetically-engineered hematopoietic stem cells can restore factor VIII (fVIII) activity to curative levels in hemophilia A mice and that human hematopoietic stem cells are readily transduced with recombinant lentivirus encoding a genetically-engineered fVIII transgene. To date, we are the only group that has obtained sustained therapeutic fVIII expression levels in hemophilia A mice using non- myeloablative transplantation regimens that are in routine clinical practice. Our gene therapy approach uses a bioengineered fVIII transgene (termed ET-3) that achieves normal fVIII activity levels (1 unit/ml) at hematopoietic stem cell transduction efficiencies (1-5%), which are achieved currently in human gene therapy clinical trials. We have generated extensive preclinical data using ET-3 demonstrating proof-of-concept that hematopoietic stem cells genetically engineered with a lentivirus vector encoding ET-3, coupled with a non-myeloablative transplant regimen, can be used to treat hemophilia A. We now propose to first conduct pre-IND meetings with the FDA to direct final preclinical testing of ET-3. Therefore, our late stage testing will be based on FDA guidance. Second, we will generate our final preclinical data set using clinical- grade (GMP) lentiviral vector encoding ET-3, which will specifically test the safety and effectiveness of the clinical product. It is anticipted that a follow up phase II project will be submitted in support of the actual clinical trial. Four organizations have partnered to accomplish these goals, including: i) Expression Therapeutics, LLC, a biotechnology company founded on the high expression fVIII technology, ii) Emory University, where the conception and proof of concept of high expression fVIII technology occurred, iii) Children's Healthcare of Atlanta, financial supporter of the Gene Therapy Program at Emory University and investor in Expression Therapeutics, LLC, and iv) Lentigen Corporation, a company dedicated to the successful clinical application of lentiviral vectors and holder of the largest lentiviral vector intellectual property portfolio. Lentigen will generate the clinical-grade recombinant lentivector that will be used in the proposed studies including the clinical trial. PUBLIC HEALTH RELEVANCE: Insufficient expression of the blood clotting factor VIII results in the bleeding disorder hemophilia A. Current treatment for this disease consists of difficult, lie-long, intravenous infusion of plasma-derived or recombinant factor VIII to restore circulating factor VIII activity levels and is currently offered to less than one-third of all hemophilia A patients due to high product cost and limited availability. Gene therapy offers a potential cure fo this debilitating and, in many parts of the world, lethal disease. We have shown that transplantation of bone marrow cells genetically-modified to express an engineered factor VIII protein is a feasible treatment for hemophilia A. In the current application, we propose to conduct late-stage pre-clinical testing to support approval of a first in man clinical gene therapy trial.