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对a型血友病患者进行基因治疗临床试验，结合转基因造血干细胞（hsc）。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移植可以将血友病a小鼠的因子VIII （fVIII）活性恢复到治疗水平，并且人类造血干细胞很容易用编码基因工程fVIII转基因的重组慢载体进行转导。我们的基因治疗方法使用由埃默里大学设计的生物工程fVIII转基因，包含关键的高表达序列，我们已经证明这是达到治疗/治愈性fVIII表达水平所必需和充分的。使用生物工程fVIII构建物，命名为ET-3，在临床前小鼠研究中，我们在植入1 - 5%的转基因造血细胞的小鼠中常规观察正常的fVIII活性水平（1单位/ml）。这些植入水平与基于人类造血干细胞的临床基因治疗试验已经达到的水平相似。相比之下，我们和其他人已经证明，使用完全人类fVIII序列的类似策略在血友病A小鼠临床前模型中不能达到这些强大的fVIII活性水平。我们已经使用ET-3转基因产生了大量的临床前数据，这些数据证明了用ET-3编码慢载体进行基因工程的造血干细胞，加上非清髓性移植方案，可用于治疗并可能治愈a型血友病。此外，召开了一次有利的ind前会议，为最终确定我们的临床前数据包和载体制造提供了必要的指导。我们现在建议1)使用临床级（GMP）慢载体产品生成后期临床前数据，2)完成批准进行试点基因治疗临床试验所需的监管文件，3)在拟议的试验中招募和治疗7名血友病a患者。为实现这些目标，四个组织建立了伙伴关系，包括：i) Expression Therapeutics， LLC，一家建立在高表达fVIII技术基础上的生物技术公司；ii) Emory大学，在那里进行了大部分临床前研究；iii) Children's Healthcare of Atlanta，一家Emory大学基因治疗项目的财务支持者和Expression Therapeutics的投资者；iv) Lentigen Corporation，一家致力于lentivector成功临床应用的公司。Lentigen将生产临床lentivecto产品，该产品将用于包括临床试验在内的拟议研究，该试验将在Emory大学由具有干细胞移植和血友病a治疗临床专业知识的专家首席研究员进行。目前SBIR II期提案的主要里程碑是将ET-3基因治疗概念和项目从临床前后期研究阶段转化为首次人体试验。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to conduct a gene therapy clinical trial incorporating genetically modified hematopoietic stem cells (HSCs) for persons with hemophilia A. In a series of recent studies, we have shown that the transplantation of genetically-engineered HSCs can restore factor VIII (fVIII) activity to curative levels in hemophilia A mice and that human HSCs are readily transduced with recombinant lentivector encoding a genetically-engineered fVIII transgene. Our gene therapy approach uses a bioengineered fVIII transgene designed at Emory University and contains critical high-expression sequences, which we have shown are necessary and sufficient to achieve therapeutic/curative fVIII expression levels. Using the bioengineered fVIII construct, designated ET-3, in preclinical murine studies we routinely observe normal fVIII activity levels (1 unit/ml) i mice engrafted with 1 - 5% genetically-modified hematopoietic cells. These engraftment levels are similar to those that have already been achieved in human HSC-based clinical gene therapy trials. In contrast, we and others have shown that similar strategies using fully human fVIII sequences do not achieve these robust fVIII activity levels in the hemophilia A mouse preclinical model. We have generated extensive preclinical data using the ET-3 transgene, which demonstrate proof-of-concept that HSCs genetically engineered with ET-3-encoding lentivector, coupled with a non-myeloablative transplant regimen, can be used to treat and possibly cure hemophilia A. In addition, a favorable pre-IND meeting was held that provided the necessary guidance needed to finalize our preclinical data package and vector manufacturing. We now propose to 1) generate late-stage preclinical data using clinical-grade (GMP) lentivector product, 2) complete the regulatory submissions necessary for approval to conduct a pilot gene therapy clinical trial and 3) recruit and treat 7 patients with hemophilia A in the proposed trial. Four organizations have partnered to accomplish these aims, including: i) Expression Therapeutics, LLC, a biotechnology company founded on the high expression fVIII technology, ii) Emory University, where the majority of the preclinical studies have been performed, iii) Children's Healthcare of Atlanta, a financial supporter of the Gene Therapy Program at Emory University and investor in Expression Therapeutics, and iv) Lentigen Corporation, a company dedicated to the successful clinical application of lentivectors. Lentigen will generate the clinical lentivecto product that will be used in the proposed studies including the clinical trial, and the trial will e conducted at Emory University by expert principal investigators with clinical expertise in stem cell transplantation and the treatment of hemophilia A. The chief milestone of the current Phase II SBIR proposal is the translation of the ET-3 gene therapy concept and project from the late-pre-clinical study phase into a first-in-man trial.