Characterization of KMT2A :: MATR3 fusion in a patient with acute lymphoblastic leukemia and monitoring of minimal residual disease by nanoplate digital PCR.
Characterization of KMT2A :: MATR3 fusion in a patient with acute lymphoblastic leukemia and monitoring of minimal residual disease by nanoplate digital PCR.
复制标题
急性淋巴细胞白血病患者 KMT2A::MATR3 融合的表征以及通过纳米板数字 PCR 监测微小残留病。
DOI：
10.1002/pbc.30120
复制
发表时间：
2022
影响因子：
3.2
通讯作者：
Saitsu H
中科院分区：
文献类型：
--
作者：
Komatsu K;Sakaguchi K;Shimizu D;Yamoto K;Kato F; Ogata T;Saitsu H
致编辑：赖氨酸甲基转移酶2A （KMT2A）重排有超过90种不同的伴侣基因。在一项大型队列研究中，报道了一例急性淋巴细胞白血病（ALL）患者中KMT2A:：基质-3 （Matrin-3）融合2；然而，患者也有MEF2D:: DAZAP1融合，KMT2A:: mat3融合的细节和临床特征不详。在本研究中，我们描述了一例ALL与KMT2A:: mat3融合的患者。此外，使用纳米板数字聚合酶链反应（PCR）监测的最小残留病（MRD）在复发后的再诱导治疗结束时显示为阴性。7岁男性，面色苍白，胸痛。全血分析显示他的白细胞计数为14010 /µl，其中胚细胞占56%。骨髓淋巴细胞占92.7%。流式细胞术检测显示，母细胞CD19、细胞质CD79a、CD24表达阳性，NG2表达阴性。患者被诊断为前体- b ALL。骨髓样品g带显示47，XY, t (5; 11)（q31; q23）。3)(图1)。此外，荧光原位杂交在98%的细胞中显示KMT2A的分裂信号（图1B）。患者在中枢神经系统及其他区域均未出现髓外病变。采用ALL-BFM95标准化疗方案。3泼尼松龙单药治疗7天后第8天外周血检查未见白血病母细胞。诱导治疗后，患者完全缓解，并被分类为中危。化疗在初次诊断后28个月完成。然而，白血病在一年后复发，复发时，淋巴细胞流式细胞检查显示除了NG2阳性和细胞质CD79a阴性外，几乎与初始诊断相似。这一发现与急性未分类白血病的诊断一致。g带检测结果与初诊一致。患者接受改良的ALL R3方案4的再诱导治疗和一个周期的blinatumumab治疗。给予blinatumumab后，IgH/TCR PCR-MRD结果为阴性。脐带血移植使用HLA - 3抗原错配供体，患者已完全缓解2年。本研究经滨松大学医学院机构审查委员会批准。在获得患者父母的知情同意后，我们从原代和复发白血病细胞中提取基因组DNA，并使用淋巴细胞技术（STEMCELL Technologies）进行分离。使用DNBSEquation （MGI TECH）对原代白血病细胞的基因组DNA进行全基因组测序分析，并使用Manta分析其结构变异。5我们鉴定出KMT2A:: mat3融合基因（图1C， D）。发现断点位于KMT2A （NM_001197104）的内含子8上。2)和MATR3 （NM_018834）的外显子2。6)。RNA分析显示帧内的KMT2A:: MATR3融合转录物，导致产生具有menin-binding motif和KMT2A的CXXC结构域以及MATR3的RRM1、RRM2和ZF2结构域的嵌合蛋白（图1E）。没有迹象表明致病的单核苷酸变异、indel和拷贝数变异与恶性肿瘤有关。为了评估MRD，使用QIAquity （QIAGEN）对26,000个分区的纳米板进行了针对KMT2A:: matri3融合断点的数字PCR。PCR引物设计…
To the Editor: There are more than 90 different partner genes for lysine methyltransferase 2A (KMT2A) rearrangements. 1 KMT2A:: Matrin-3 (MATR3) fusion has been reported in a patient with acute lymphoblastic leukemia (ALL) in a large cohort study 2; however, the patient also had MEF2D:: DAZAP1 fusion, and the details of KMT2A:: MATR3 fusion and clinical features were unavailable. In the present study, we characterized a patient with ALL and KMT2A:: MATR3 fusion. Furthermore, minimal residual disease (MRD) monitoring using nanoplate digital polymerase chain reaction (PCR) showed negative MRD at the end of re-induction therapy following relapse. A 7-year-old male presented with a pale complexion and chest pain. The complete blood analysis showed that his white blood cell count was 14,010/µl, with 56% blast cells. The bone marrow contained 92.7% lymphoblasts. Flow cytometry (FCM) showed that the blast cells were positive for CD19, cytoplasmic CD79a, and CD24, while negative for NG2. The patient was diagnosed with precursor-B ALL. Moreover, G-banding of bone marrow samples showed 47, XY, t (5; 11)(q31; q23. 3)(Figure 1A). Further, fluorescence in situ hybridization showed a split signal of KMT2A in 98% cells (Figure 1B). The patient presented no extramedullary disease in the central nervous system nor other regions. The patient was treated with the standard chemotherapy based on ALL-BFM95 protocol. 3 No leukemic blasts were indicated in the peripheral blood test at day 8 following 7 days of prednisolone monotherapy. After induction therapy, the patient achieved complete remission and was classified as medium risk. The chemotherapy was completed 28 months after the initial diagnosis. However, the leukemia relapsed after a year, and at relapse, the FCM of lymphoblasts showed an almost similar diagnosis to that of the initial, except for the positive NG2 and negative cytoplasmic CD79a indications. This finding is consistent with the diagnosis of acute unclassified leukemia. The result of G-banding was consistent with that of the initial diagnosis. The patient was treated with re-induction therapy of modified ALL R3 protocol 4 and one cycle of blinatumomab. The IgH/TCR PCR-MRD result was negative following blinatumomab administration. Umbilical cord blood transplantation was performed using an HLA 3 antigen-mismatched donor, and the patient has been in complete remission for 2 years. This study was approved by the Institutional Review Board of Hamamatsu University School of Medicine. After obtaining an informed consent from his parents, we extracted genomic DNA from primary and relapsed leukemic cells, which were isolated using Lymphoprep (STEMCELL Technologies). Genomic DNA from primary leukemic cells was analyzed by whole-genome sequencing using DNBSEquation (MGI TECH) with 150-bp paired-end reads, and the structural variants were analyzed by Manta. 5 We identified a KMT2A:: MATR3 fusion gene (Figure 1C, D). The breakpoint was found to reside in intron 8 of KMT2A (NM_001197104. 2) and exon 2 of MATR3 (NM_018834. 6). The RNA analysis showed an in-frame KMT2A:: MATR3 fusion transcript, leading to the production of a chimeric protein with menin-binding motif and CXXC domain of KMT2A, as well as RRM1, RRM2, and ZF2 domains of MATR3 (Figure 1E). There were no indications for pathogenic singlenucleotide variants, indel, and copy number variations associated with malignancy. To assess MRD, digital PCR targeting KMT2A:: MATR3 fusion breakpoint was performed using QIAquity (QIAGEN) with a nanoplate of 26,000 partitions. PCR primers were designed …