慢性髓系白血病首发血小板显著增多

本研究探讨以血小板显著增多首发的慢性髓系白血病（CML）临床、细胞遗传学及分子生物学特征。应用骨髓细胞涂片、骨髓活检观察细胞形态学改变;RT-PCR检测bcr／abl融合基因;常规染色体核型分析及FISH检测细胞遗传学变化。结果发现：以血小板显著增多为首发表现的CML是一组具有独特临床和生物学特点的疾病,骨髓细胞涂片和骨髓活检表明,骨髓增生活跃,以巨核系异常增生为主,血小板大片戍堆,可见圆形核小巨核细胞,中等度白细胞增多,经细胞遗传学和分子生物学检测均证实存在有Ph染色体和（或）表达bcr／abl融合基因,对此类患者应该早期进行积极治疗,甚至进行分子生物学水平的干预;而原发性血小板增多症（ET）患者则不宜过多地使用化疗药物,否则反而诱致白血病的发生。结论：对血小板明显增多的患者应及时进行Ph染色体及bcr／abl融合基因表达水平的检测．这对于ET及CML的诊断和鉴别诊断极为重要,以避免误诊、误治。     

慢性髓系白血病急变期分子遗传学研究进展

9号和22号染色体相互易位产生Ph染色体及BCR-ABL融合基因,几乎在所有慢性髓系白血病（CML）出现,BCR-ABL编码的蛋白具有持续增高的酪氨酸激酶活性,使白血病细胞异常增殖。急变期是CML的晚期,在此期间常常出现其它附加染色体和分子的改变。大量研究表明,BCR-ABL基因与其他失调的基因共同作用并异常激活下游的信号传导通路,促进了疾病的进展。酪氨酸激酶抑制剂伊马替尼对大多数慢性期CML患者治疗效果显著。IRIS5年的临床试验显示：用伊马替尼治疗的98%患者达血液学完全缓解,92%患者达主要细胞遗传学缓解,87%患者达完全细胞遗传学缓解。然而,仍有少数慢性期和大多数进展期患者用伊马替尼治疗疗效欠佳。在耐药机制的研究中发现ABL激酶区点突变与临床耐药关系密切。第二代酪氨酸激酶抑制剂可改善伊马替尼耐药,本文就急性变的分子机制、伊马替尼耐药等做一综述。     

罕见的ins(22;9)t(9;13)/Ph~-慢性髓系白血病实验研究

本文报告1例罕见的具有ins(22;9)t(9;13)的Ph(-)慢性髓系白血病。骨髓细胞经24小时短期培养法制备染色体标本,采用G显带技术进行核型分析;用9号、22号全染色体涂染探针进行染色体涂染;用LSI bcr/abl双色双融合探针进行FISH分析;用实时荧光定量PCR法检测bcr/abl融合基因转录本及其拷贝数。结果表明,染色体核型为45,XX,der(9)t(9;13)(q34;q10),-13[20],abl基因插入到der(22)形成插入性的bcr/abl基因重排;实时荧光定量PCR检测到bcr/abl融合基因。结论:插入性的bcr/abl基因重排是t(9;22)的一种罕见的变异类型,可用分子学方法检测,但全染色体涂染及常规的染色体显带分析容易导致误诊。     

Kaposi's sarcoma in a patient treated with imatinib mesylate for chronic myeloid leukemia

Background: Chronic myeloid leukemia (CML) is a myeloproliferative disorder primarily characterized by the presence of the Philadelphia chromosome resulting from a reciprocal translocation between the long arms of chromosomes 9 and 22. This translocation determines a fusion gene, bcr-abl, which encodes a constitutively active protein, tyrosine kinase, resulting in decreased apoptosis, defective adhesion, and genomic instability in transformed cells. The tyrosine kinase activity and its effects represent a potential pharmacologic target of tyrosine kinase inhibitors, such as imatinib. Flare of Kaposi's sarcoma (KS) is well described in immunosuppressed patients treated with corticosteroids and rituximab, but has not yet been reported during treatment with imatinib.Objective: We report a case of cutaneous KS lesions in a patient affected by CML treated with imatinib.Case summary: A 61-year-old white male patient (weight, 90 kg) was diagnosed with CML in March 2006 at the Division of Hematology, University of Rome “Tor Vergata,” Rome, Italy. He was treated with imatinib 400 mg/d, which improved his general condition with few adverse effects. After 12 months of treatment, molecular biology showed an important reduction in the peripheral blood of the fusion oncoprotein bcr-abl p210-b3a2. However, at the same time, multiple cutaneous violaceous papular-nodular lesions appeared on his left forearm. A punch biopsy showed the presence of KS, whereas a polymerase chain reaction assay documented the presence of human herpes virus type 8 (HHV8) DNA in the skin lesion. Serologic HIV was negative and HHV8 viremia was under the limit of quantitation of the assay. Total body computed tomography scan did not reveal any mucosal or visceral lesion.Conclusions: We present a case of a patient with CML who developed KS 12 months after starting treatment with imatinib 400 mg/d. The mechanism behind the development of the cutaneous lesions is unclear, and could have either a casual clinical association or be related to the study drug. According to the Naranjo adverse drug reaction probability scale, the development of KS in this case was probably associated with the imatinib treatment (score, 5–8).     

Treating chronic myeloid leukaemia: NICE guidance

Chronic myeloid leukaemia (CML) affects approximately 560 people annually in the UK. Although median age at diagnosis is 60 years (National Institute for Health and Clinical Excellence (NICE), 2012), CML occurs in all age groups (National Comprehensive Cancer Network (NCCN), 2012). It is a clonal myeloproliferative disorder which is characterized by a reciprocal translocation between chromosomes 9 and 22, resulting in the formation of the Philadelphia chromosome (Ph Chromosome) and the development of an unregulated tyrosine kinase (BCR-ABL) which is responsible for the pathogenesis of CML (NCCN, 2012).     

Dasatinib treatment for imatinib resistant or intolerant patients with chronic myeloid leukaemia

Chronic myeloid leukaemia (CML) is a genetically associated malignancy of haematopoietic stem cells, characterized by a t(9;22) translocation that forms the Philadelphia chromosome and creates a novel fusion gene, BCR-ABL. Treatment with molecular-targeted therapy is usually initiated with imatinib, an inhibitor of BCR-ABL tyrosine kinase. Imatinib resistance is, however, observed in some CML patients, especially in those with advanced disease. Through computerized literature searches, a systematic analysis was conducted to examine the efficacy and benefits of dasatinib therapy for imatinib resistant or intolerant CML patients in the chronic phase (CP), accelerated phase (AP) and fatal blast crisis phase (BC). In terms of major haematological and cytogenetic responses, this meta-analysis showed no significant differences in dasatinib treatment between myeloid BC-CML and lymphoid BC-CML patients with imatinib resistance or intolerance. Dasatinib therapy was, however, significantly more effective in improving major haematological and cytogenetic responses for CP-CML patients than for AP-CML patients with imatinib resistance or intolerance.     

Oncogenes and their involvement in chronic myelogenous leukemia

This review highlights recent developments in the oncogene field relating to the molecular biology of chronic myelogenous leukemia (CML). At least 90% of patients diagnosed with CML carry an abnormal chromosome within their tumor cells. This chromosome is known as the Philadelphia chromosome. It results in most cases from an exchange of genetic material between chromosomes 9 and 22. As a result of this exchange the cellular abl gene from chromosomes 9, which is related to a viral oncogene, becomes fused to a region of chromsome 22 called the breakpoint cluster region (bcr). The hybrid bcr-abl gene is believed to play an important role in the disease process. The product of the fused bcr and abl genes is a 210,000 mol. wt. protein termed P210^bcr-abl. It has an associated protein kinase activity that phosphorylates tyrosine residues. Tyrosine protein kinases are thought to play an important role in the formation of tumors by rapidly acting RNA tumor viruses such as Abelson mouse leukemia virus. This virus has acquired part of the cellular abl gene from the mouse genome; viral infected tumor cells express a hybrid protein called P120^gag-abl, a tyrosine kinase believed to be responsible for the tumor phenotype. Similarly, P210^bcr-abl may play a key role in maintaining the tumor properties of leukemic cells of the CML patient.     

Chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) represents about 14% of all leukemias and occurs with a frequency of about 1 in 100,000. It is rare in children. Symptoms include fatigue, weight loss, sweating, and abdominal discomfort from an enlarged spleen. The white blood cell count can range from 100-600 ul. CML has three phases: the chronic phase, accelerated phase, and blast phase. Most patients are diagnosed during the chronic phase. Ionizing radiation has been implicated in some cases of CML, but in most individuals no cause is known. The Philadelphia chromosome, an acquired genetic mutation represented by a translocation of chromosome 22 and chromosome 9, drives the leukemic changes in CML. Imatinib mesylate, a tyrosine kinase inhibitor, was approved in 2002 for the treatment of all phases of CML. Because of its effectiveness, imatinib has become the treatment of choice for most patients with CML. Stem cell transplantation also is an option for eligible patients. It is the only curative treatment for CML. Two drugs under study for patients who cannot tolerate or who become resistant to imatinib are BMS-354825 and AMN107. Oncology nurses who are knowledgeable about new therapies for CML can be effective resources for their patients.     

Growth Arrest of BCR-ABL Positive Cells with a Sequence-Specific Polyamide-Chlorambucil Conjugate

Chronic myeloid leukemia (CML) is characterized by the presence of a constitutively active Abl kinase, which is the product of a chimeric BCR-ABL gene, caused by the genetic translocation known as the Philadelphia chromosome. Imatinib, a selective inhibitor of the Bcr-Abl tyrosine kinase, has significantly improved the clinical outcome of patients with CML. However, subsets of patients lose their response to treatment through the emergence of imatinib-resistant cells, and imatinib treatment is less durable for patients with late stage CML. Although alternative Bcr-Abl tyrosine kinase inhibitors have been developed to overcome drug resistance, a cocktail therapy of different kinase inhibitors and additional chemotherapeutics may be needed for complete remission of CML in some cases. Chlorambucil has been used for treatment of B cell chronic lymphocytic leukemia, non-Hodgkin's and Hodgkin's disease. Here we report that a DNA sequence-specific pyrrole-imidazole polyamide-chlorambucil conjugate, 1R-Chl, causes growth arrest of cells harboring both unmutated BCR-ABL and three imatinib resistant strains. 1R-Chl also displays selective toxicities against activated lymphocytes and a high dose tolerance in a murine model.     

1例伴有t(9;22)和ins(3;8)的慢性粒细胞白血病的临床和实验研究

目的报道1例伴有ins(3;8)的慢性粒细胞白血病(CML)病例及其3号、8号全染色体涂染、双色间期荧光原位杂交(FISH)、实时荧光定量PCR研究结果。方法骨髓细胞经直接法或24 h短期培养法制备染色体标本,R显带技术进行核型分析;3号、8号全染色体涂染探针进行染色体涂染;bcr/abl双色双融合探针进行FISH分析;实时荧光定量PCR检测bcr/abl融合基因转录本及其拷贝数。结果骨髓细胞R显带核型分析提示,除t(9;22)外,所有细胞伴ins(3;8);全染色体涂染证实3号染色体上插入一段8号来源的染色体片段;双色FISH检测到bcr/abl基因重排;实时荧光定量PCR检测到bcr/abl融合基因(b3a2)转录本。结论ins(3;8)是CML患者罕见的附加染色体异常;全染色体涂染是明确染色体插入易位的可靠手段。     

Antileukemic drug--a selective inhibitor of BCR-ABL tyrosine kynase, imatinib(STI571)]

Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell disorder characterized by Philadelphia chromosome and resultant production of the constitutively activated BCR-ABL tyrosine kinase. Imatinib (STI571), selective inhibitor of the ABL-tyrosine kinase, inhibits the activity of BCR-ABL tyrosine kinase. A phase I and II study of STI571 showed remarkable cytogenetic effect in patients with interferon-refractory CML, offering new hope for therapy for CML. It will, however, require long-term follow-up data from phase II and III clinical studies to validate the effect of STI571 on survival. As therapy for CML improves, monitoring minimal residual disease will be important.     

8p11骨髓增殖综合征的研究现状

8p11骨髓增殖综合征(8p11 myeloproliferative syndrome,EMS)是与定位于髓系和淋巴系细胞8号染色体短臂(8p11)的成纤维细胞生长因子受体1(FGFR1)基因易位相关的侵袭性肿瘤。EMS以外周血白细胞计数明显增高、骨髓中髓系增生、嗜酸细胞增多和淋巴母细胞淋巴瘤/白血病为特征。EMS短期内将进展为急性白血病。EMS预后差,目前只有异基因造血干细胞移植能有效控制该病。在分子水平,所有病例均涉及8p11的FGFR1基因易位,新融合蛋白通过诱导FGFR1基因二聚体化,组成性激活酪氨酸激酶活性,导致细胞增殖及恶性转化。迄今,已鉴定出的与FGFR1形成融合蛋白的伙伴基因有14例(包括13例易位与1例插入),现就其分子生物学特征、发病机制和治疗等的研究现状作一综述。     

New insights into small‐molecule inhibitors of Bcr‐Abl

Chronic myelogenous leukemia (CML) is a myeloproliferative disease associated with a defined genetic abnormality, the Bcr‐Abl fusion gene on the Philadelphia chromosome that expresses the constitutively activated tyrosine kinase (TK) Bcr‐Abl. This enzyme leads to the malignant transformation of primitive hematopoietic cells and to the consequent disease. The central role of Bcr‐Abl in the pathogenesis of CML culminated in the discovery of imatinib (an ATP‐competitive inhibitor), which is currently the frontline therapy for CML. Unfortunately, the initial enthusiasm generated by its high response rate has been dampened by the development of resistance, especially in the advanced phases of CML. To overcome imatinib resistance, several second‐generation ATP‐competitive inhibitors endowed with increased potency against imatinib‐resistant mutants have been developed: the dual Src/Abl inhibitor dasatinib and the Abl inhibitor nilotinib have been recently approved by US‐FDA for the treatment of imatinib‐resistant CML, and many other compounds are currently in clinical trial. Although second‐generation TK inhibitors have shown to be clinically effective against most of the imatinib‐resistant mutants, to date poor results have been obtained in the treatment of the Bcr‐Abl T315I mutant. In this review we will report the most interesting second‐generation Abl and dual Src/Abl inhibitors recently entered in clinical trial, but also the new ATP‐competitive and uncompetitive inhibitors published in the last few years, focusing on their chemical structure, mechanism of action, and structure–activity relationship. © 2009 Wiley Periodicals, Inc. Med Res Rev, 31, No. 1, 1–41, 2010     

Dasatinib: a tyrosine kinase inhibitor for the treatment of chronic myelogenous leukemia and philadelphia chromosome-positive acute lymphoblastic leukemia

BACKGROUND: The Philadelphia chromosome is formed from a translocation of genetic material involving human chromosomes 9 and 22. The resulting gene product, BCR-ABL, encodes for an abnormal tyrosine kinase (TK) that is a factor in the pathology of chronic myelogenous leukemia (CML). Use of targeted therapy that inhibits BCR-ABL kinase activity may lead to hematologic and cytogenetic responses in affected individuals. The oral TK inhibitor dasatinib was approved in 2006 for use in patients with CML or Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) who are unable to tolerate or have not responded to other treatments. OBJECTIVE: This paper reviews the available data on dasatinib, including its pharmacokinetic and pharmacodynamic properties, findings of in vitro and in vivo studies, adverse effects, and potential place in therapy. METHODS: Pertinent information was identified through searches of MEDLINE (1966-May 2007), EMBASE (1980-first quarter 2007), and International Pharmaceutical Abstracts (1970-May 2007) using the terms dasatinib, BMS-354825, chronic myelogenous leukemia, Sprycel, Philadelphia chromosome, and acute lymphoblastic leukemia. All clinical studies and case reports published at the time of the search were included in this review. RESULTS: Observed mutations in the amino acid sequence of BCR-ABL cause the failure of treatment with existing TK inhibitors. Dasatinib has shown in vitro and in vivo activity against BCR-ABL, including mutations that are resistant to other available TK inhibitors. Preliminary results are available from several noncomparative studies of dasatinib in patients who were unable to tolerate or were resistant to previous therapies. The 5 phases of START (SRC/ABL Tyrosine kinase inhibition Activity Research Trials of dasatinib) represent the largest and most comprehensive evaluation of dasatinib in the treatment of patients in all stages of CML or Philadelphia chromosome-positive ALL who had undergone previous treatment for leukemia. Dasatanib had the greatest benefit in patients in the chronic phase of CML, with complete hematologic responses in 90% of patients, 52% of whom achieved a major hematologic response. Compared with those in the chronic phase, patients in the accelerated phase or blast crisis of CML, or with Philadelphia chromosome-positive ALL had lower responses. In the START-R trial, which compared the response to dasatinib and high-dose imatinib (800 mg/d), both regimens had comparable ability to induce a complete hematologic response (95% and 93%, respectively), although more patients achieved a major cytogenetic response with dasatinib (32% vs 7%). Adverse effects include significant myelosuppression. Dasatinib may have the potential for use in the management of nonleukemic malignancies. CONCLUSIONS: Dasatinib has a wider spectrum of activity against a broader range of BCR-ABL forms than existing TK inhibitors. It has shown clinical benefit and tolerability in patients in all phases of CML, as well as in those with Philadelphia chromosome-positive ALL. Dasatinib illustrates the potential for targeted drug development based on an understanding of the genetic alterations leading to CML and the development of resistance to treatment.     

Molecular methods to detect the Philadelphia chromosome

The Ph1 chromosome has two molecular subtypes: a bcr-positive seen in CML and some cases of ALL, and the bcr-negative subtype mainly seen in ALL. In CML, because of the restriction of chromosome 22 breakpoints to the bcr, Southern analysis to detect bcr rearrangements also can be used to detect the Ph1 chromosome. In contrast, the translocation breakpoints on the Ph1 chromosome are scattered in ALL, so that other methods such as PFGE and PCR are necessary to detect the Ph1 chromosome. In both CML and ALL, use of these methods to detect molecular abnormalities may be superior to cytogenetics in detecting chromosomal abnormalities. Southern analysis also can be used in CML to map breakpoint locations within the bcr. This may offer prognostic information as to the length of chronic phase, but there is conflicting information as to the validity of this approach. The modified PCR (using cDNA from mRNA) can be used to detect the Ph1 chromosome and to define which of the molecular subtypes are present. The exquisite sensitivity of this method, which is capable of detecting as little as a single abnormal molecule of RNA or DNA, makes it suited for the detection of minimal residual disease in both CML and ALL. This is particularly useful after intensive therapies, such as bone marrow transplantation. Whether these low levels of fusion gene expression are of prognostic significance is still unclear.     

CXCR4 up-regulation by imatinib induces chronic myelogenous leukemia (CML) cell migration to bone marrow stroma and promotes survival of quiescent CML cells

Chronic myelogenous leukemia (CML) is driven by constitutively activated Bcr-Abl tyrosine kinase, which causes the defective adhesion of CML cells to bone marrow stroma. The overexpression of p210Bcr-Abl was reported to down-regulate CXCR4 expression, and this is associated with the cell migration defects in CML. We proposed that tyrosine kinase inhibitors, imatinib or INNO-406, may restore CXCR4 expression and cause the migration of CML cells to bone marrow microenvironment niches, which in turn results in acquisition of stroma-mediated chemoresistance of CML progenitor cells. In KBM5 and K562 cells, imatinib, INNO-406, or IFN-alpha increased CXCR4 expression and migration. This increase in CXCR4 levels on CML progenitor cells was likewise found in samples from CML patients treated with imatinib or IFN-alpha. Imatinib induced G0-G1 cell cycle block in CML cells, which was further enhanced in a mesenchymal stem cell (MSC) coculture system. MSC coculture protected KBM-5 cells from imatinib-induced cell death. These antiapoptotic effects were abrogated by the CXCR4 antagonist AMD3465 or by inhibitor of integrin-linked kinase QLT0267. Altogether, these findings suggest that the up-regulation of CXCR4 by imatinib promotes migration of CML cells to bone marrow stroma, causing the G0-G1 cell cycle arrest and hence ensuring the survival of quiescent CML progenitor cells.     

成人慢性髓性白血病骨髓细胞血管内皮生长因子的表达

血管生成出现于实体瘤生长的早期,抗血管生成可能成为治疗实体瘤的一个新的策略。血管内皮生长因子（vascular endothelial growth factor,VEGF）是人类实体瘤中主要的促血管生成细胞因子之一,其在慢性髓性白血病（chronic myelogenous leukemia,CML）病程进展中是否呈现过度表达尚不清楚。为此,本研究采用RT-PCR和ELISA方法对CML病人骨髓细胞及血浆VEGF的表达进行了研究。结果表明,多数CML细胞、白血病细胞系及正常人骨髓细胞均表达VEGF,CML病人VEGF mRNA检测阳性率（93.1%)高于骨髓移植后的CML病人（50%）及正常人（60%）;未治CML病人血浆VEGF浓度（380.6pg/ml）比CML骨髓移植后病人血浆的VEGF浓度（38.0%pg/ml)高9倍;未治CML骨髓细胞分泌的VEGF（499.8pg/ml)比正常人骨髓细胞分泌的（141.3pg/ml)多2.5倍,两之间有显性差异（P＜0.05)。研究结果说明VEGF在CML病人中确实存在过度表达,其在CML发病机制中的作用值得进一步深入研究。