RETROVIRAL VECTOR-MEDIATED LIVER GENE THERAPY FOR MPS I

描述（由申请人提供）：粘多糖病I （MPS I）是一种溶酶体贮积病，由a- l -伊杜糖醛酸酶（IDUA）活性不足引起，导致糖胺聚糖肝素和硫酸皮聚糖的积累。严重的形式，被称为Hurler综合征，会导致骨骼和关节异常，肺部和心脏疾病，听力和视力缺陷，智力迟钝，如果不治疗，会在5岁左右死亡。造血干细胞移植可以减少一些症状，但死亡率为15%，费用为13万美元，并且需要匹配的供体。酶替代疗法也可以减轻一些症状，但成年人每年的费用超过50万美元，需要每周输液，并不是所有患者都可以使用。开发一种有效而安全的基因疗法来治疗MPS I，可能会对患者和照顾他们的家庭的生活产生巨大的积极影响。在之前的资助期内，我们证明了新生儿静脉注射具有完整长端重复序列（LTR）表达犬IDUA的γ逆转录病毒载体（g-RV）对患有MPS I的小鼠和犬具有真正显着的效果，消除或减少了所有主要临床表现。这至少部分是由于肝细胞的有效转导，其分泌甘露糖6-磷酸（M6P）修饰的IDUA进入血液，扩散到其他器官并通过M6P受体被吸收。还有一些血细胞的转导和大脑中一种未定义的细胞类型，这可能有助于治疗反应。虽然这种方法在小鼠或狗身上没有发生肿瘤，但ltr完整载体的插入突变风险令人担忧。另一个问题是，将这种载体应用于成年MPS I小鼠或新生MPS I猫，会导致强烈的细胞毒性T淋巴细胞（CTL）反应，破坏换能器细胞。这项更新申请的目的是：1)通过开发具有3' LTR增强子缺失的自我失活g-RV来降低插入突变的风险；2)试图通过避免抗原呈递细胞的表达来阻止免疫反应；3)在长寿大型动物模型（犬）上分析其药效持续时间和毒性评价。如果成功，这项研究可能会加速开发一种简单有效的新生儿治疗方法，减少或预防MPS I的破坏性临床表现。

DESCRIPTION (provided by applicant): Mucopolysaccharidosis I (MPS I) is a lysosomal storage disease caused by deficient a-L-iduronidase (IDUA) activity, which results in the accumulation of the glycosaminoglycans heparan and dermatan sulfate. The severe form, known as Hurler syndrome, causes bone and joint abnormalities, pulmonary and cardiac disease, hearing and visual deficiencies, mental retardation, and death around age 5 if untreated. Hematopoietic stem cell transplantation can reduce some manifestations, but has a 15% mortality rate, costs $130,000, and requires a compatible donor. Enzyme replacement therapy can also reduce some symptoms, but costs over $500,000 per year for an adult, requires a weekly infusion, and is not available to all patients. The development of an effective and safe gene therapy for MPS I could have a dramatic positive impact on the lives of patients and the families that care for them. In the previous funding period, we demonstrated that neonatal intravenous injection of a gamma retroviral vector (g-RV) with an intact long-terminal repeat (LTR) expressing canine IDUA had a truly remarkable effect in both mice and dogs with MPS I, with elimination or reduction in all major clinical manifestations. This was due at least in part to efficient transduction of liver cells, which secreted mannose 6-phosphate (M6P)-modified IDUA into blood, which diffused to other organs and was taken up via the M6P receptor. There was also some transduction of blood cells and an undefined cell type in brain, which may have contributed to the therapeutic response. Although no tumors developed in mice or dogs with this approach, the risk of insertional mutagenesis with an LTR-intact vector is a concern. Another problem is that administration of this vector to adult MPS I mice or newborn MPS I cats resulted in a potent cytotoxic T lymphocyte (CTL) response that destroyed transducer cells. The aims of this renewal application are to: 1) reduce the risk of insertional mutagenesis by developing a self-inactivating g-RV with a deletion in the enhancer of the 3' LTR; 2) attempt to prevent an immune response by avoiding expression in antigen-presenting cells; and 3) analyze the duration of efficacy and evaluate for toxicity in a long-lived large animal model (dog). If successful, this study may hasten the development of a simple and effective treatment for newborn patients that will reduce or prevent the devastating clinical manifestations of MPS I. Public Health Relevance: The goal of this project is to develop a simple and effective treatment for patients with mucopolysaccharidosis I (MPS I). MPS I results in heart, lung, bone, joint, and neurological disease, and in the severe form known as Hurler syndrome is fatal around age 5 if untreated. The goal of this project is to develop a retroviral vector that can be administered shortly after birth, and will result in long-standing correction of the clinical manifestations. This study will also test to see if there are any adverse effects of gene therapy. This may result in a treatment for patients with this severe genetic disease.