Lentiviral Gene Therapy and Genome Editing for X-linked Severe Combined Immunodeficiency

项目摘要--项目3 该项目的总体目标是确定慢病毒基因治疗联合亚消融白花丹 条件反射可用于治疗多种严重联合免疫缺陷(XSCID)患者。 这种儿童时期的灾难性疾病是由IL2RG基因突变引起的，这种突变导致严重的缺陷 在T细胞、NK细胞和B细胞介导的免疫。异基因移植是标准的治疗方法，但会导致 在缺乏匹配兄弟姐妹捐赠者的患者中，结果不佳。虽然之前的伽马基因治疗试验- 逆转录病毒载体显示临床益处，不完全免疫重建和载体相关白血病 在相当多的案例中都可以看到。我们提出了一种新的方法，使用安全修饰的慢病毒载体和 经骨髓移植建立长期矫正的低强度调理 造血干细胞。在过去的资助期间，我们开启了第一批慢病毒临床试验 消融治疗XSCID，迄今已治疗12例，效果显著。这个 NIH临床中心的LVXSCID-OC试验招募了8名免疫力减弱的XSCID患者，尽管 曾接受过同种异体移植。这些病例显示出高水平的髓系标志 在以前的XSCID基因治疗试验中是史无前例的，在某些情况下是完全免疫重建。在……里面 特别是，在前两个病例中，B细胞功能恢复，导致脱离丙种球蛋白 替代疗法，这在以前的基因治疗试验中没有得到。我们还新开了一家 在圣犹大、加州大学旧金山分校和西雅图的诊断方案(LVXSCID-ND)，并治疗了四名转换的婴儿 在过去的七个月里，定向亚消融条件下的骨髓细胞。中国的基因标记技术 血液和骨髓髓系细胞一直很高，并与快速重建 T细胞和NK细胞的数量和功能。B细胞标记水平平均为0.8拷贝/细胞，并已注意到 其中一例有内源性丙种球蛋白产生的初步证据。基于这些结果，我们 现在寻求支持以通过验证更多GMP级载体批次来完成这两个阶段的研究， 完成两个方案的登记，并执行详细的、长期的免疫重建分析， 媒介标记/克隆研究，以及这些病例的临床安全性。我们预计这些研究将提供 一种治疗XSCID的新疗法，并导致这种基因疗法的商业化，从而使这种疗法 可以被广泛使用。

PROJECT SUMMARY – PROJECT 3 The overall goal of this project is to determine if lentiviral gene therapy combined with subablative busulfan conditioning can be used to treat a broad spectrum of patients with severe combined immunodeficiency (XSCID). This catastrophic disease of childhood is caused by mutations in the IL2RG gene that lead to profound defects in T cell, NK cell, and B-cell mediated immunity. Allogeneic transplant is the standard therapy, but results in suboptimal outcomes in patients that lack matched sibling donors. While prior gene therapy trials with gamma- retroviral vectors showed clinical benefit, incomplete immune reconstitution and vector-related leukemia was seen in a significant number of cases. We propose a new approach using a safety-modified lentiviral vector and reduced intensity conditioning in order establish long-term correction via bone marrow engraftment of transduced hematopoietic stem cells. During the past funding period, we opened the first clinical lentiviral trials with subablative busulfan for XSCID and have obtained remarkable success in 12 cases treated thus far. The LVXSCID-OC trial at the NIH Clinical Center has enrolled eight XSCID patients who had waning immunity despite having undergone a prior allogeneic transplant. These cases have shown high levels of myeloid marking that are unprecedented in prior XSCID gene therapy trials and complete immune reconstitution in some cases. In particular, B cell function was restored in the first two cases leading to independence from gamma-globulin replacement therapy, which has not been obtained in prior gene therapy trials. We have also opened a newly diagnosed protocol (LVXSCID-ND) at St. Jude, UCSF, and Seattle and have treated four infants with transduced bone marrow cells following targeted subablative conditioning over the past seven months. Gene marking in blood and bone marrow myeloid cells has been very high and has been associated with rapid reconstitution of T and NK cell numbers and function. B cell marking levels have averaged 0.8 copies/cell and have been noted with preliminary evidence of endogenous gamma-globulin production in one case. Based on these results, we now seek support to complete both of these Phase I studies by validating more GMP-grade vector batches, completing enrollment on both protocols, and performing detailed, long term analyses of immune reconstitution, vector marking/clonality studies, and clinical safety in these cases. We anticipate that these studies will provide a new therapy for XSCID and leading to commercialization of this gene therapy approach so that this treatment can be made widely available.