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Abstract：
Stem cell gene therapy using the MFGS-gp91phox retroviral vector was performed on a 27-year-old patient with X-linked chronic granulomatous disease (X-CGD) in 2014. The patient\'s refractory infections were resolved, whereas the oxidase-positive neutrophils disappeared within 6 months. Thirty-two months after gene therapy, the patient developed myelodysplastic syndrome (MDS), and vector integration into the MECOM locus was identified in blast cells. The vector integration into MECOM was detectable in most myeloid cells at 12 months after gene therapy. However, the patient exhibited normal hematopoiesis until the onset of MDS, suggesting that MECOM transactivation contributed to clonal hematopoiesis, and the blast transformation likely arose after the acquisition of additional genetic lesions. In whole-genome sequencing, the biallelic loss of the WT1 tumor suppressor gene, which occurred immediately before tumorigenesis, was identified as a potential candidate genetic alteration. The provirus CYBB cDNA in the blasts contained 108 G-to-A mutations exclusively in the coding strand, suggesting the occurrence of APOBEC3-mediated hypermutations during the transduction of CD34-positive cells. A hypermutation-mediated loss of oxidase activity may have facilitated the survival and proliferation of the clone with MECOM transactivation. Our data provide valuable insights into the complex mechanisms underlying the development of leukemia in X-CGD gene therapy.
摘要：
2014年，对一名27岁的X连锁慢性肉芽肿病（X-CGD）患者进行了使用MFGS-gp91phox逆转录病毒载体的干细胞基因治疗。患者的难治性感染得到解决，而氧化酶阳性中性粒细胞在6个月内消失。基因治疗32个月后,患者出现骨髓增生异常综合征(MDS),并且在胚细胞中鉴定了载体整合到MECOM基因座中。在基因治疗后12个月，在大多数骨髓细胞中可检测到载体整合到MECOM中。然而,患者表现出正常的造血，直到MDS发作，表明MECOM反式激活有助于克隆造血，并且爆炸转化可能在获得额外的遗传损伤后出现。在全基因组测序中，WT1抑癌基因的双等位基因缺失，发生在肿瘤发生之前，被确定为潜在的候选遗传改变。原始细胞中的前病毒CYBBcDNA仅在编码链中包含108个G到A突变，提示在CD34阳性细胞转导过程中发生APOBEC3介导的超突变。超突变介导的氧化酶活性丧失可能促进了具有MECOM反式激活的克隆的存活和增殖。我们的数据为X-CGD基因治疗中白血病发展的复杂机制提供了有价值的见解。
