慢性粒细胞白血病治疗新进展:第52届美国血液学年会热点

慢性粒细胞白血病(chronic myelogenous leukemia,CML)是一种起源于造血干细胞的恶性增殖性疾病,以9号和22号染色体异位形成费城染色体(Ph)为特征,该异位形成一种新的bcr-abl融合基因,此基因编码的融合型蛋白能导致髓系造血的异常克隆性增殖.     

塞来昔布对慢性粒细胞白血病原代细胞bcr-abl融合蛋白的影响

目的 探讨塞来昔布对慢性粒细胞白血病(CML)原代细胞bcr-abl融合基因的mRNA表达、p210蛋白表达和蛋白质酪氨酸激酶(PTK)活性的影响.方法 以不同浓度的塞来昔布(0、10、20、40、80、160 μmol/L)分别干预CML原代细胞36 h,进行荧光实时定量反转录聚合酶链反应(RQ-RTPCR)、Western blotting和PTK活性检测.结果 80～160μmol/L的塞来昔布下调bcr-abl的mRNA表达;随着塞来昔布浓度增加,p210蛋白表达逐步下调;40μmol/L以上的塞来昔布能明显抑制PTK活性,但非浓度依耐性.结论 塞来昔布能不同程度地下调CML原代细胞bcr-abl的mRNA和蛋白表达,并抑制PTK活性.     

Ph阴性伴Y染色体缺失的不典型慢性粒细胞白血病一例并文献复习

目的 对一例Ph阴性、bcr-abl融合基因阴性伴Y染色体缺失的不典型慢性粒细胞白血病(CML)患者进行荧光原位杂交(FISH)分析,以检测其是否存在隐蔽的bcr-abl基因重排,排除bcr-abl融合基因假阴性可能,验证其Y染色体缺失的异常核型.方法 采用位点特异性探针GLPbcr-abl(绿/红)额外信号(ES)探针检测bcr-abl基因重排;采用着丝粒探针CSP 18/CSP X/CSP Y(蓝/绿/红)检测Y染色体缺失.结果 GLP bcr-abl ES探针计数200个间期细胞,100%为两红、两绿信号,Ph染色体为阴性;着丝粒CSP 18/CSPX/CSP Y探针计数200个间期细胞,67%细胞为两蓝一绿信号,色信号丢失,存在Y染色体缺失.结合其病情特点,Y染色体缺失为后天获得性.该例Ph阴性、bcr-abl融合基因阴性伴Y染色体缺失的不典型CML患者预后差.结论 Ph阴性、bcr-abl融合基因阴性伴Y染色体缺失的不典型CML患者病情进展凶险,预后差;FISH技术检测染色体异常特异、可靠,有助于对不典型CML患者确诊,关于不典型CML患者的分子生物学本质有待进一步病例积累及研究揭示.     

异基因造血干细胞移植在慢性粒细胞白血病治疗中仍有一定地位

慢性粒细胞白血病(CML)是成年人常见的白血病,我国CML的年发病率稍低于西方国家.对CML的治疗而言,酪氨酸激酶抑制剂(TKI)--伊马替尼(imatinb mesylate,IM)的问世是继白消安(myleran,busulfan)、羟基脲(hydroxyurea)、干扰素(IFN-α)、异基因造血干细胞移植(allo-BMT)之后的又一个新的里程碑[1].IM对CML的治疗取得了卓越的治疗效果,其对初治的慢性期CML血液学的缓解率达90%以上,细胞遗传学缓解率可达80%以上,甚至部分病例可获得分子学的缓解(CMoR)[2-3].     

伊马替尼联合粒细胞集落刺激因子治疗慢性粒细胞白血病11例

目的 研究伊马替尼(IM)联合粒细胞集落刺激因子(G-CSF)降低单药IM疗效欠佳的慢性粒细胞白血病(CML)残留病的疗效.方法 采用IM联合G-CSF治疗11例IM治疗后Ph染色体转阴率≥35%的CML患者.起始治疗量为IM 400或600 mg/d,G-CSF 5μg·kg-1·d-1,皮下注射.白细胞计数≥30×109/L者,延迟或间断使用G-CSF直至白细胞＜20×109/L.治疗过程中定期检测外周血bcr-abl转录水平,治疗6个月后转录水平降低未超过0.5个对数(log)者,停用G-CSF.bcr-abl转录水平持续下降但仍未获得完全分子生物学缓解者,继续使用该方案治疗1～6个月.结果 11例患者中9例出现bcr-abl转录水平的明显下降(包括7例下降＞1个对数和2例下降＞0.5个对数),2例出现bcr-abl转录水平的下降小于0.5个对数.7例下降＞1个对数者,其中2例获得完全分子生物学缓解,5例原为部分细胞遗传学缓解的患者获得完全细胞遗传学缓解.所有患者均能耐受,未出现因不良反应中断治疗和治疗相关性死亡病例.结论 IM联合G-CSF方案治疗单药lM治疗反应欠佳的CML患者有效、安全.     

急性白血病造血干细胞移植后胸壁粒细胞肉瘤复发一例并文献复习

目的 观察急性白血病造血干细胞移植(HSCT)后孤立性胸壁粒细胞肉瘤(GS)复发的临床特点.方法 回顾性分析1例急性髓系白血病(AML)患者异基因HSCT(allo-HSCT)后3年并发孤立性胸壁GS的临床资料.结果 患者胸部CT发现心膈角处肿物,经手术发现肿物原发于胸壁,切除后病理诊断为GS,经化疗以及局部放疗后治愈,目前无复发迹象,仍在定期随访中.结论 化疗联合局部放疗是治疗髓外孤立性GS的较好的方法,对于AML-HSCT的患者,需要注意髓外复发病灶的检测.     

低剂量地西他滨联合伊马替尼对K562细胞的增殖抑制作用

目的 研究低剂量地西他滨(DAC)联合伊马替尼(IM)对K562细胞株的增殖抑制作用及对bcr-abl表达的影响.方法 单药及两药联合后,通过四甲基偶氮唑蓝(MTT)法观察药物对K562细胞株的增殖抑制作用,流式细胞术检测药物对K562细胞株早期凋亡率及细胞周期,巢式反转录-聚合酶链反应(RT-PCR)半定量检测药物对K562细胞株bcr-abl mRNA表达.结果 DAC与IM单药对K562细胞的抑制作用呈浓度时间依赖性.两药联合用药抑制作用较单药组明显(F=43.947、165.580、321.193、296.101,均P<0.05),24、48、72 h各浓度组与对照组比较差异均有统计学意义(F=202.759、168.457、417.538,均P<0.05).DAC及IM单药作用药物对K562细胞株均使G,期细胞明显增多,IM0.2μmol/L作用于K562细胞株48 h可见6.7%早期凋亡细胞,IM 0.2 μmol/L联合DAC 4μmol/L早期凋亡细胞增加至8.4%.bcr-abl mRNA表达水平降低,DAC 4 μmol/L作用48 h后可降低K562细胞中bcr-abl mRNA表达(约14%),IM 0.2 μmol/L降低约40%,联合用药表达量明显降低(约60%).联合用药组与单药组比较差异有统计学意义(F=71.981,P<0.05).结论 DAC对K562细胞的增殖抑制作用与细胞周期阻滞、诱导凋亡及降低bcr-abl mRNA表达有关,两药联合可显著抑制K562细胞增殖.     

应用LSI9q34探针及ES/DCDF探针检测慢性粒细胞白血病患者der(9)缺失的研究

目的 研究慢性粒细胞性白血病(CML)患者衍生9号染色体[der(9)]部分序列缺失情况,探讨LSI 9q34探针在检测der(9)缺失中的联合应用价值.方法 对52例CML患者采用不加任何刺激剂的骨髓进行24 h短期培养法制备染色体,吉姆萨显带进行核型分析.应用ES/DCDF探针及LSI 9q34探针对骨髓间期细胞进行荧光原位杂交,并检测der(9)部分序列缺失.结果 52例中经ES/DCDF探针检测全部为ber-abl融合基因阳性,其中12例患者伴有der(9)部分缺失,占23.0%,经LSI 9q34探针检测有11例患者伴有der(9)部分缺失.结论 LSI9q34探针在判断CML患者是否伴有der(9)缺失方面有较好的特异性.伴有缺失的患者疾病进展较快,预后较差,甲磺酸依马替尼治疗不能完全逆转其负性作用,建议所有bcr-abl融合基因阳性的CML患者均应行 LSI 9q34探针检测,以指导临床治疗.     

急性髓系白血病自体造血干细胞移植后长期生存并正常生育三例

目的 探讨造血干细胞移植(HSCT)对患者生育功能的影响.方法 回3例接受自体造血干细胞移植(auto-HSCT)后长期生存并正常生育的急性髓系白血病(AML)患者的临床资料,并复习相关文献.结果 3例AML患者中,女1例,男2例,接受不含全身放疗预处理方案的auto-HSCT,分别在停止治疗后68、65和65个月生育一健康小孩.结论 育龄期接受HSCT患者的生育问题在制定治疗方案时应引起重视.     

粒细胞集落刺激因子对供体造血干细胞移植物中树突状细胞的影响

目的 探讨粒细胞集落刺激因子(G-CSF)对正常异基因造血干细胞移植供者外周血与骨髓移植物中Ⅰ型树突状细胞(DC1)、Ⅱ型树突状细胞(DC2)的数量及DC2/DC1比例的影响.方法 以G-CSF每天10μg/kg动员5 d后,以流式细胞术(FCM)检测11例G-CSF动员的异基因外周血造血干细胞移植物及20例G-CSF动员的异基因骨髓移植物中的DC1、DC2数量及DC2/DC1比例,并与8例正常供者动员前外周血及10例健康者动员前骨髓进行比较.结果 动员前后骨髓DC2由14.37×106/L增至29.68×106/L(t=2.433,P=0.022),而骨髓DC1分别为13.77×10a/L和18.88×106/L(t=0.625,P=0.541);DC2/DC1比例在动员后为1.83±0.81,较动员前的1.12±0.32明显升高(t=2.685,P=0.013).正常供者以G-CSF动员前、后移植物中外周血DC2数量分别为14.92×106/L和26.76×106/L(t=2.390,P=0.029),DC2/DC1比例分别为1.00±0.37和2.02±1.43(t=2.158,P=0.044),但外周血DC1分别为14.21×106/L和18.02×106/L(t=0.625,P=0.541).结论 移植前以G-CSF动员正常异基因干细胞移植供者,可选择性提高外周血及骨髓移植物中DC2的数量,而DC1数量无明显增加.     

Genetic marking shows that Ph+ cells present in autologous transplants of chronic myelogenous leukemia (CML) contribute to relapse after autologous bone marrow in CML

Relapse after autologous bone marrow transplantation for chronic myelogenous leukemia (CML) can be due either to the persistence of leukemia cells in systemic tissues following preparative therapy, or due to the persistence of leukemia cells in the autologous marrow used to restore marrow function after intensive therapy. To help distinguish between these two possible causes of relapse, we used safety-modified retroviruses, which contain the bacterial resistance gene NEO, to mark autologous marrow cells that had been collected from patients early in the phase of hematopoietic recovery after in vivo chemotherapy. The cells were then subjected to ex vivo CD34 selection following collection and 30% of the bone marrow were exposed to a safety-modified virus. This marrow was infused after delivery of systemic therapy, which consisted of total body irradiation (1,020 cGy), cyclophosphamide (120 mg/kg), and VP-16 (750 mg/m2). RT PCR assays specific for the bacterial NEO mRNA, which was coded for by the virus, and the bcr-abl mRNA showed that in two evaluable CML patients transplanted with marked cells, sufficient numbers of leukemia cells remained in the infused marrow to contribute to systemic relapse. In addition, both normal and leukemic cells positive for the retroviral transgenome persisted in the systemic circulation of the patients for at least 280 days posttransplant showing that the infused marrow was responsible for the return of hematopoiesis following the preparative therapy. This observation shows that it is possible to use a replication-incompetent safety-modified retrovirus in order to introduce DNA sequences into the hematopoietic cells of patients undergoing autologous bone marrow transplantation. Moreover, this data suggested that additional fractionation procedures will be necessary to reduce the probability of relapse after bone marrow transplantation in at least the advanced stages of the disease in CML patients undergoing autologous bone marrow transplantation procedures.     

Bcr-Abl efficiently induces a myeloproliferative disease and production of excess interleukin-3 and granulocyte-macrophage colony-stimulating factor in mice: a novel model for chronic myelogenous leukemia

The bcr-abl oncogene plays a critical role in causing chronic myelogenous leukemia (CML). Effective laboratory animal models of CML are needed to study the molecular mechanisms by which the bcr-abl oncogene acts in the disease progression of CML. We used a murine stem cell retroviral vector (MSCV) to transduce the bcr-abl/p210 oncogene into mouse bone marrow cells and found that expression of Bcr-Abl/p210 induced a myeloproliferative disorder that resembled the chronic phase of human CML in 100% of bone marrow transplanted mice in about 3 weeks. This CML-like disease was readily transplanted to secondary recipient mice. Multiple clones of infected cells were expanded in the primary recipients, but the leukemia was primarily monoclonal in the secondary recipient mice. Mutation analysis demonstrated that the protein tyrosine kinase activity of Bcr-Abl/p210 was essential for its leukemogenic potential in vivo. Interestingly, we found that the leukemic cells expressed excess interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the diseased mice. These studies demonstrate that expression of Bcr-Abl can induce a CML-like leukemia in mice much more efficiently and reproducibly than in previously reported mouse CML models, probably due to efficient expression in the correct target cell(s). Our first use of this model for analysis of the molecular mechanisms involved in CML raises the possibility that excess expression of hematopoietic growth factors such as IL-3 and GM-CSF may contribute to the clinical phenotype of CML.