Foamy Viral Gene Therapy for X-linked Severe Combined Immune Deficiency

描述（由申请人提供）：我们提出了一个基础和转化研究的综合计划，以开发泡沫病毒（FV）载体为基础的基因替代疗法，用于患有遗传性严重联合免疫缺陷SCID-X1的患者。该计划涉及三个科学项目和四个核心。其中两个科学项目专注于使用动物模型研究FV载体SCID-X1基因治疗：项目1 -小鼠和人类SCID-X1的FV基因治疗的临床前建模，以及项目2 -犬SCID-X1模型中的FV介导的基因治疗。这些项目将测试关键假设的安全性和有效性的FV载体应用结合先进的非清髓性预处理方案？c基因替代疗法。另一个科学项目，项目3 -FV载体SCID-X1基因治疗的第二代方法，将测试与FV载体系统和技术相关的关键假设，目的是进一步提高FV载体的安全性和性能。这三个项目将得到四个核心项目的支持，以便有效地利用共同的方法和技术。在五年的支持期内，该计划旨在为SC 1D-X1提供一种综合基因替代疗法，包括具有良好特征的第一代临床？c FV载体和先进的预处理方案，完全准备好用于人类SCID-X1临床试验。此外，该计划将提高我们对FV载体系统和FV载体技术的认识;并启动第二代？c FV载体系统和综合疗法预计将在安全性和有效性方面取得进一步进展。总体而言，我们的工作预计将导致安全和新的未来疗法，包括直接体内FV载体基因递送的有效方法， 人类SCID-X1以及其他遗传疾病所需的基因。 相关性：该项目将为患有灾难性免疫缺陷SC 1D-X1的患者创造一种新型的基因疗法。它还将在基因治疗和干细胞移植方面取得进展，有可能为许多其他类型的血液和免疫系统遗传性疾病提供更安全，更有效的治疗方法。 项目1 -泡沫病毒基因治疗的临床前建模 项目负责人（PL）：大卫J.罗林斯 （申请人提供的描述）：SCID-X1是由常见γ链（？c）基因。虽然使用匹配的同胞供体进行干细胞移植可以治愈，但大多数患者缺乏最佳供体，导致预后较差。基因置换作为SCID-X1的替代治疗方法具有许多理论优势;使用γ逆转录病毒的开创性临床研究？C递送导致显著的益处以及由于病毒增强剂触发的白血病发生而导致的意外不良事件。该PPG的总体假设是，？使用基于重组泡沫病毒（FV）的载体可以显著改善c基因递送。项目1中的研究旨在检验以下假设：不含病毒增强子的cFV载体（具有或不具有位于转录盒侧翼的另外的增强子阻断元件）将表现出足以在体内进行功能拯救的转基因表达水平，同时显示出降低的遗传毒性。项目1的目的是通过详细的表型，功能和分子分析来测试这些假设：1）SCID-X1的小动物模型和2）来自SCID-X1患者的造血干细胞（HSC）。我们的具体研究将包括1）EF 1？-什么？c FV载体在骨髓清除与非骨髓清除小鼠SCID-X1受体中的体内研究;以及替代的体外反式激活试验; 2）临床前和GMP级第1代？c转导的SCID-X1患者CD 34 + BM细胞中的FV;和3）候选绝缘的第2代？c来自SCID-X1小鼠和人类患者的HSC中的FV载体。项目1将使用所有4个核心，并将在多个层面上与项目2和项目3内的工作进行对接。结合项目2和项目3的数据，我们的研究将为未来的第一代和第二代SCID-X1 FV载体临床试验提供有关有效性、安全性和最佳载体设计的关键数据。 相关性：SCID-X1是严重的免疫系统疾病，由？c基因。基因治疗预计将为SCID-X1提供有益的治疗。然而，以前的方法虽然有益，但也导致高频率的不良事件。本PPG的目标是使用基于重组泡沫病毒（FV）的载体开发安全有效的SCID-X1基因递送。项目1中的研究旨在测试候选临床SCID-X1 FV载体将在SCID-X1的小鼠和人类模型中拯救功能，同时显示遗传毒性降低的想法。

DESCRIPTION (provided by applicant): We propose an integrated program of basic and translational research to develop foamy virus (FV) vector- based gene replacement therapy for patients who suffer from the inherited severe combined immunodeficiency SCID-X1. The program involves three scientific Projects and four Cores. Two of the scientific projects are focused on studying FV vector SCID-X1 gene therapy using animal models: Project 1 - Pre-clinical modeling of FV gene therapy for murine and human SCID-X1, and Project 2 - FV mediated gene therapy in the canine SCID-X1 model. These projects will test key hypotheses regarding the safety and efficacy of FV vectors applied in conjunction with advanced non-myeloablative conditioning regimens for ?c gene replacement therapy. The other scientific project, Project 3 - Second generation approaches to FV vector SCID-X1 gene therapy, will test key hypotheses related to FV vector systems and technology, with the goal of further enhancing FV vector safety and performance. The three Projects will be supported by four Cores to provide for efficient use of common methods and technology. Over the five year period of support, the program is designed to yield an integrated gene replacement therapy for SC1D-X1 consisting of a well characterized 1st generation clinical ?c FV vector and an advanced conditioning regimen that is fully ready for translation to a human SCID-X1 clinical trial. In addition, the program wil advance our knowledge of FV vector systems and FV vector technology; and initiate pre-clinical evaluation of 2nd generation ?c FV vector systems and integrated therapies anticipated to lead to future further advances in safety and efficacy. Overall, our work is predicted to lead to safe and novel future therapies, including efficient methods for direct in vivo FV vector gene delivery, needed for human SCID-X1 as well other genetic disorders. RELEVANCE: This project will create a new type of gene therapy for patients who suffer from the catastrophic immunodeficiency SC1D-X1. It will also generate advances in gene therapy and stem cell transplantation that have the potential to lead to safer and more effective therapies for many other types of inherited diseases of the blood and immune system. PROJECT 1 - Pre-clinical Modeling of Foamy Viral Gene Therapy Project Leader (PL): David J. Rawlings (Description as provided by applicant): SCID-X1 is catastrophic immunodeficiency disorder caused by mutations within the common gamma chain (?c) gene. While stem cell transplantation using a matched sibling donor can be curative, most patients lack optimal donors leading to poorer outcomes. Gene replacement has many theoretical advantages as an alternative therapeutic approach for SCID-X1; and pioneering clinical studies using gammaretroviral ?c delivery lead to both significant benefit as well as unanticipated adverse events due to viral enhancer triggered leukemogenesis. The overarching hypothesis of this PPG is that both the efficacy and safety of ?c gene delivery can be significantly improved using recombinant foamy virus (FV) based vectors. Studies in Project 1 are designed to test the hypotheses that ?c FV vectors devoid of viral enhancers (with or without additional enhancer blocking elements flanking the transcriptional cassette) will exhibit levels of transgene expression sufficient for functional rescue in vivo while concurrently showing reduced genotoxicity. The aims of Project 1 are designed to test these hypotheses via detailed phenotypic, functional, and molecular analysis in both: 1) a small animal model of SCID-X1 and 2) hematopoietic stem cells (HSC) derived from SCID-X1 patients. Our specific studies will include efficacy and safety assessment of 1) EF1?-hu-?c FV vectors in vivo in myeloablated vs. non-myeloablated murine SCID-X1 recipients; and in alternative in vitro transactivation assays; 2) Preclinical and GMP-grade 1st generation ?c FV in transduced SCID-X1 patient CD34+ BM cells; and 3) Candidate insulated 2nd generation ?c FV vectors in HSC from SCID-X1 mice and human patients. Project 1 will utilize all 4 Cores and will interface on multiple levels with work within both Projects 2 and 3. In conjunction with data derived from Projects 2 and 3, our studies will provide key data regarding efficacy, safety and optimal vector design for future 1st and 2nd generation SCID-X1 FV vector clinical trials. RELEVANCE: SCID-X1 is severe immune disorder caused by mutations in the ?c gene. Gene therapy is predicted to provide a beneficial treatment for SCID-X1. However, previous approaches, while beneficial, also lead to a high frequency of adverse events. The goal of this PPG is develop safe and effective SCID-X1 gene delivery using recombinant foamy virus (FV) based vectors. Studies in Project 1 are designed to test the idea that candidate clinical SCID-X1 FV vectors will rescue function in mouse and human models of SCID-X1 while concurrently showing reduced genotoxicity.