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

描述（由申请人提供）：我们提出一个综合的基础和转化研究项目，开发基于泡沫病毒（FV）载体的基因替代疗法，用于遗传性严重联合免疫缺陷SCID-X1患者。该计划涉及三个科学项目和四个核心。两个科学项目主要研究猪瘟病毒载体SCID-X1基因治疗动物模型：项目1 -小鼠和人SCID-X1的猪瘟病毒基因治疗临床前建模，项目2 -猪瘟病毒介导的SCID-X1犬模型的基因治疗。这些项目将测试关于FV载体与先进的非清髓性调节方案联合应用的安全性和有效性的关键假设。C基因替代疗法。另一个科学项目，项目3 -第二代FV载体SCID-X1基因治疗方法，将测试与FV载体系统和技术相关的关键假设，目标是进一步提高FV载体的安全性和性能。这三个项目将得到四个核心的支持，以便有效地利用共同的方法和技术。在5年的支持期内，该项目旨在为SC1D-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载体和一种先进的调理方案，已经完全准备好转化为人类SCID-X1临床试验。此外，该计划将推进我们对FV矢量系统和FV矢量技术的了解；启动第二代的临床前评估？FV载体系统和综合疗法有望在安全性和有效性方面取得进一步进展。总的来说，我们的工作预计将导致安全和新颖的未来治疗，包括直接在体内传递FV载体基因的有效方法，

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.