Safer Vectors and Strategies For Gene Therapy

描述（由申请人提供）：逆转录病毒载体是将基因产物稳定地传递到治疗目的细胞的优秀工具。然而，在临床环境中使用这些载体最近被证明是有问题的。在一项纠正严重联合免疫缺陷（SCID）的基因治疗试验中，11名患者中有2名患者直接由于综合逆转录病毒载体而患上了t细胞白血病。为了防止在未来的基因治疗试验中出现不良后果，本研究的主要目标是开发和测试新的载体和策略，旨在提高安全性而不丧失有效性。新的载体将被开发，不太可能导致插入突变，同时仍然保留治疗的好处。这将需要具有增强子阻断活性的DMA元件的工程来抑制基因组DMA中邻近基因的转激活。纳入可调节的自杀基因（在出现不良结果时可被激活）将提供额外的安全功能。最后，上述讨论的载体和策略以及有限数量的转基因细胞的使用将在小鼠免疫缺陷模型中测试它们拯救遗传缺陷的能力。这个项目的目的是在保证有效性的同时保证安全性，生产最安全、最有效的逆转录病毒载体，用于人类基因治疗试验。

DESCRIPTION (provided by applicant): Retroviral vectors are excellent tools for the stable delivery of gene products into cells of therapeutic interest. However, use of these vectors in a clinical setting has recently been shown to be problematic. In a gene therapy trial for the correction of Severe Combined Immune Deficiency (SCID), two patients, out of eleven, developed T-cell leukemia as a direct result of an integrated retroviral vector. In an effort to prevent undesirable outcomes in future gene therapy trials, a primary goal of this study is the development and testing of novel vectors and strategies aimed at increased safety without the loss of effectiveness. New vectors will be developed that are less likely to lead to insertional mutagenesis while still retaining the therapeutic benefits. This will require the engineering of DMA elements with enhancer-blocking activity to inhibit transactivation of adjacent genes in genomic DMA. Incorporation of a regulatable suicide gene, which could be activated in the case of an adverse outcome, will provide an additional safety feature. Lastly, the vectors and strategies discussed above along with the use of limited numbers of genetically modified cells will be tested for their ability to rescue a genetic defect in a murine model of immunodeficiency. This project is aimed at tempering efficacy with safety in producing the safest, most potent retroviral vectors for use in human gene therapy trials.