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

项目概要-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消安是否 预处理可用于治疗广泛的严重联合免疫缺陷（XSCID）患者。 这种灾难性的儿童疾病是由IL 2 RG基因突变引起的，导致严重的缺陷 在T细胞、NK细胞和B细胞介导免疫中。同种异体移植是标准疗法，但结果 缺乏匹配的同胞供体的患者的次优结果。先前的基因治疗试验- 逆转录病毒载体显示出临床效益，不完全免疫重建和载体相关白血病， 在很多情况下都可以看到。我们提出了一种新的方法，使用安全修饰的慢病毒载体， 降低强度的预处理，以便通过骨髓移植转导的 造血干细胞在过去的资助期间，我们启动了第一个临床慢病毒试验， 12例治疗均获显著疗效。的 NIH临床中心的LVXSCID-OC试验招募了8名免疫力下降的XSCID患者， 之前接受过同种异体移植这些病例显示出高水平的骨髓标记， 在先前的XSCID基因治疗试验中是前所未有的，并且在某些情况下完全免疫重建。在 特别是，前两个病例中B细胞功能恢复，导致不依赖于γ-球蛋白 替代疗法，这在先前的基因治疗试验中尚未获得。我们还新开了一家 诊断方案（LVXSCID-ND）在圣裘德，加州大学旧金山分校和西雅图，并已治疗了四名婴儿与转导 在过去的七个月里，骨髓细胞在靶向亚烧蚀处理后。基因标记 血液和骨髓的髓样细胞已经非常高，并已与快速重建， T和NK细胞数量和功能。B细胞标记水平平均为0.8拷贝/细胞， 在一个病例中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，通过验证更多GMP级载体批次来完成这两项I期研究， 完成两种方案的入组，并进行详细的长期免疫重建分析， 载体标记/克隆性研究以及这些情况下的临床安全性。我们预计，这些研究将提供 一种新的XSCID治疗方法，并导致这种基因治疗方法的商业化， 可以广泛使用。

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.