Treatment of Leukocyte Adhesion Deficiency by Foamy Virus Vectors

描述（由申请人提供）：白细胞粘附缺乏症（LAD）是造血干细胞（HSC）基因治疗可能治愈的许多疾病之一。在LAD中，CD18基因的突变阻止血细胞的表达，从而无法迁移到组织中，导致危及生命的细菌感染。同种异体骨髓移植治疗LAD，但可能存在显著的方案相关毒性和移植物抗宿主病，并且许多患者缺乏hla匹配的供体。虽然干细胞基因疗法在治疗某些遗传疾病方面取得了显著的成功，但使用的病毒载体激活原癌基因可能导致恶性肿瘤。因此，需要一种基因毒性较小的载体来有效地转导造血干细胞。泡沫病毒（FV）载体是一种替代逆转录病毒载体系统，它比其他类型的逆转录病毒或慢病毒载体具有更小的遗传毒性。已有研究表明，表达CD18的FV载体可以治愈犬LAD （CLAD）模型。本文提出的实验将开发和测试FV载体治疗人类LAD。这些载体将分析其在人类细胞（包括LAD患者的造血细胞）中的有效性和安全性。将探讨诸如绝缘体之类的特定遗传因素对降低FV载体的遗传毒性负责的可能性。准备用于临床使用的GMP级载体库存。还将对先前用流行性出血热病媒治疗过的确诊犬再进行5年随访，以在大型动物模型中提供长期数据。拟议的实验将为LAD基因治疗试验提供必要的临床前数据，它们对有前途的FV载体系统的未来发展至关重要。

DESCRIPTION (provided by applicant): Leukocyte adhesion deficiency (LAD) is one of many diseases with the potential to be cured by hematopoietic stem cell (HSC) gene therapy. In LAD, mutations in the CD18 gene prevent expression in blood cells that then fail to migrate into tissues, resulting in life-threatening bacterial infections. LAD has been treated with allogeneic bone marrow transplantation, but there can be significant regimen-related toxicity and graft-versus-host disease, and many patients lack an HLA-matched donor. While there have been notable successes in treating some genetic diseases with stem cell gene therapy, proto-oncogene activation by the viral vectors used can cause malignancies. Thus there is a need for less genotoxic vectors that efficiently transduce HSCs. Foamy Virus (FV) vectors are an alternative retroviral vector system that is less genotoxic than other types of retroviral or lentiviral vectors. Prior research showed that the canine model of LAD (CLAD) could be cured by FV vectors expressing CD18. The experiments proposed here will develop and test FV vectors to treat human LAD. These vectors will be analyzed for efficacy and safety in human cells, including hematopoietic cells from LAD patients. The possibility that specific genetic elements such as insulators are responsible for the reduced genotoxicity of FV vectors will be explored. A GMP grade stock of the vector intended for clinical use will be prepared. The CLAD dogs previously treated with FV vectors will also be followed for 5 additional years to provide long-term data in a large animal model. The proposed experiments will generate essential preclinical data for an LAD gene therapy trial and they are crucial for the future development of the promising FV vector system.