伊马替尼治疗血小板增多症及其他骨髓增殖性疾病的研究及应用

临床数据显示,甲磺酸伊马替尼在治疗慢性髓系白血病(CML)过程中出现血小板降低等副反应,因此考虑将伊马替尼应用于血小板增多症及其他骨髓增殖性疾病(MPD)。研究证实,伊马替尼不仅可以抑制BCR/ABL突变基因,对其他酪氨酸激酶受体基因如PDGFR、JAK2V617F及C-KIT突变同样也有抑制作用,从而为MPD提供了重要的靶向治疗潜能。由于PDGFR、JAK2及C-KIT在骨髓造血中发挥着重要作用,提示伊马替尼可能正是通过阻滞PDGFR、JAK2V617F及C-KIT受体磷酸化阻断受体的信号传导通路,打断细胞分化增殖反应,从而起到治疗效果。本文总结伊马替尼在血小板增多症及其他骨髓增殖性疾病中的研究和应用,并探究其中的可能机制。     

甲磺酸伊马替尼治疗慢性髓性白血病的护理

近年来血液病临床医疗、科研进展很快，新的诊疗技术不断涌现，已使不少恶性难治性血液疾病被攻克成为可能，甲磺酸伊马替尼在体内外均可在细胞水平上抑制Bcr—Abl酪氨酸激酶，能选择性抑制Bcr—Abl阳性细胞系细胞、pH染色体阳性的慢性粒细胞白血病和急性淋巴细胞白血病病人的新鲜细胞的增殖和诱导其凋亡。此外，甲磺酸伊马替尼还可抑制血小板衍化生长因子（PDGF）受体、干细胞因子（SCF）、c-Kit受体的酪氨酸激酶，     

耐甲磺酸伊马替尼慢性髓系白血病治疗策略研究进展

抑制BCR—ABL酪氨酸激酶作为慢性髓系白血病的靶向治疗,已经取得了显著的临床疗效。但对现有药物甲磺酸伊马替尼逐渐显现的原发及继发耐药,为CML治疗带来了新的挑战。针对BCR—ABL酪氨酸激酶及耐伊马替尼机制寻找新的更为有效的治疗靶点是目前探索的热点。本文对目前伊马替尼失效的机制和影响BCR—ABL酪氨酸激酶途径新靶点的研究作一综述。     

甲磺酸伊马替尼治疗慢性髓性白血病的护理

近年来血液病临床医疗、科研进展很快,新的诊疗技术不断涌现,已使不少恶性难治性血液疾病被攻克成为可能,甲磺酸伊马替尼在体内外均可在细胞水平上抑制Bcr-Abl酪氨酸激酶,能选择性抑制Bcr-Abl阳性细胞系细胞、pH染色体阳性的慢性粒细胞白血病和急性淋巴细胞白血病病人的新鲜细胞的增殖和诱导其凋亡.此外,甲磺酸伊马替尼还可抑制血小板衍化生长因子(PDGF)受体、干细胞因子(SCF)、c-Kit受体的酪氨酸激酶,从而抑制由PDGF和干细胞因子介导的细胞行为.     

髓系肿瘤PDGFRB基因异常的多态性及临床特点

伴有PDGFRB基因异常及嗜酸细胞增多的髓系肿瘤是2008版WHO分类中提出的新的一类髓系肿瘤。检查我院2 000余例髓系细胞异常病例,共发现伴PDGFRB基因异常的髓系肿瘤12例。本研究归纳此12例伴PDGFRB基因异常的髓系肿瘤病例的临床及实验室检查特点,并根据文献进行总结分析。结果表明,12例PDGFRB基因异常中TEL/PDGFRB融合基因5例,HIP1/PDGFRB异常2例,PDGFRB突变1例、RABAPTIN-5/PDGFRB、GIT2/PDG-FRB、TP53/PDGFRB、WDR48/PDGFRB融合基因各1例,显示出该基因异常的多态性。此类髓系肿瘤绝大多数病例有不同程度单核细胞及嗜酸细胞增多,血小板异常增多主要见于不典型的MPN、AL、CMML患者。部分病例采用酪氨酸激酶抑制剂甲磺酸伊马替尼治疗有效。结论:PDGFRB基因异常髓系肿瘤是一类异质性的髓系肿瘤,其基因异常类型与临床表现呈多态性,常有不同程度的嗜酸细胞及单核细胞增多,采用酪氨酸激酶抑制剂治疗可能有效。     

酪氨酸激酶时代慢性粒细胞白血病治疗的选择

慢性粒细胞白血病（chronic myeloid leukemia,CML）是造血干细胞恶性克隆性增生疾病。约95%的CML患者都有特异的细胞遗传学改变,即产生BCR-ABL融合基因。甲磺酸伊马替尼的出现为CML的治疗带来了革命性的进展,但耐药及不耐受患者的出现使得二代酪氨酸激酶抑制剂（tyrosine kinase inhibiton,TKI）达沙替尼、尼洛替尼应运而生。二代TKI转化时机及如何选择二代TKI成为关注的热点。在酪氨酸激酶时代,造血干细胞地位又将如何被看待？我们应该怎样选择CML的治疗方案？     

伊马替尼体外诱导Kasumi-1细胞增殖、分化与凋亡作用

目的探讨酪氨酸激酶抑制剂伊马替尼诱导携带c-k it突变的细胞增殖、分化与凋亡的作用。方法应用MTT比色法观察伊马替尼对Kasum i-1细胞的生长抑制作用,流式细胞术分析细胞周期、c-k it抗原和髓系分化抗原CD11b、CD13和CD15的表达,AnnexinⅤ标记和DNA凝胶电泳分析细胞凋亡,应用W estern b lot方法分析Kasum i-1细胞c-k it蛋白酪氨酸磷酸化水平。结果伊马替尼呈时间和剂量依赖性抑制Kasum i-1细胞生长,72 h半数抑制浓度(IC50)为4.45μmol/L;伊马替尼5.00μmol/L使Kasum i-1细胞阻滞于G0/G1期,S期细胞减少;髓系分化抗原CD11b、CD13和CD15表达增加;作用24 h,早期凋亡细胞比例由9.04%升至86.84%(P<0.05),培养第5天出现明显DNA梯形条带;作用72 h,Kasum i-1细胞中c-k it蛋白酪氨酸磷酸化水平下降。结论酪氨酸激酶抑制剂伊马替尼能够抑制携带c-k it突变的细胞的生长,诱导细胞分化和凋亡。     

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。     

慢性粒细胞白血病干细胞生物学特性研究进展

慢性粒细胞白血病(CML)是一种造血干细胞(HSC)恶性克隆性疾病,其典型特征是费城染色体阳性(Ph+)并表达具有强酪氨酸激酶活性的BCR/ABL融合蛋白。近年来,BCR/ABL酪氨酸激酶的信号转导抑制剂甲磺酸伊马替尼在CML治疗中的成功应用,开辟了CML靶向治疗的新途径。然而,甲磺酸伊马替尼不能根除白血病细胞克隆,容易出现耐药与复     

PDGF/PDGFR在原发性血小板增多症中的作用及机制

目的:通过检测原发性血小板增多症(ET)患者骨髓中PDGF-BB及骨髓细胞中PDGFR-β的表达探讨PDGF/PDGFR在ET中的作用及机制;通过抑制巨核细胞PDGFR探索治疗ET新靶点。方法:用ELISA方法对比ET患者及健康人的骨髓血清中PDGF-BB的表达水平;用流式细胞技术检测PDGFR-β(CD140)在ET患者及健康人骨髓中的表达;用流式细胞术或Western blot检测PDGF-BB对JAK2/STAT3、AKT通路磷酸化水平表达的影响,并观察PDGFR抑制剂伊马替尼对该作用的影响。结果:PDGF-BB在ET患者骨髓血清中表达水平显著高于健康者,且ET患者骨髓中PDGFR-β的表达显著高于健康者;PDGF-BB可刺激巨核细胞JAK2/STAT3、PI3K/AKT信号通路的活化,但可被伊马替尼阻断。结论:PDGF-BB表达水平的异常增高可能是ET发生的潜在机制,其作用机制可能是通过结合PDGFR,进而激活JAK2/STAT3、PI3K/AKT信号通路,刺激巨核细胞的增殖并抑制其凋亡;而酪氨酸激酶抑制剂则可通过阻断PDGFR,发挥治疗原发性血小板增多症的作用。     

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     

慢性髓细胞白血病的酪氨酸激酶抑制剂耐药机制

近年,慢性髓细胞白血病(CML)的治疗方法不断取得进展,包括药物化疗、脾切除术、干扰素治疗、造血干细胞移植(HSCT)等方法.第一代酪氨酸激酶抑制剂(TKI)伊马替尼,可使CML患者的总体生存(OS)率与无事件生存(EFS)率均显著提高,已成为CML的一线治疗药物.然而,部分CML患者出现原发性或继发性TKI耐药,成为导致CML患者治疗失败的主要原因.探索TKI耐药机制、寻找应对TKI耐药的新策略成为CML相关研究热点.TKI耐药的机制复杂,与多种基因产物与细胞内信号分子相关,主要分为断裂点簇集区/Abelson白血病病毒(BCR/ABL)依赖途径与非BCR/ABL依赖途径,而这些耐药机制可以单独或同时存在于同一例CML患者.随着相关研究的深入,对CML患者TKI耐药机制的研究取得较大进展,笔者拟就相关研究进展进行综述.     

慢性粒细胞白血病患者酪氨酸激酶抑制剂的耐药管理

酪氨酸激酶抑制剂(TKI)的应用使慢性粒细胞白血病(CML)的治疗发生了革命性的变化,但是随着其在临床中的广泛应用,耐药成为临床治疗中面临的巨大挑战.二代、三代TKI.及某些新型药物的研发给一代TKI伊马替尼(IM)耐药的患者带来了新的治疗选择和希望.不断完善的疗效监测体系和ABL激酶区突变检测的应用为TKI的选择、疗效评价,以及药物转换提供了客观且敏感的指标.因此,只有将治疗药物与相应的监测体系相结合,才能使CML患者得到更为合理和规范的治疗.本文拟就CML患者使用TKI耐药后,治疗方案选择及疗效监测体系的研究进展进行阐述.     

Kinase inhibitors in chronic myelogenous leukemia

The Bcr-Abl tyrosine kinase inhibitor imatinib mesylate launched the era of molecular targeted therapy and constitutes a milestone in oncology history. However, despite impressive cytogenetic response rates achieved with this agent in patients with chronic myelogenous leukemia (CML) in chronic phase, those with advanced-stage CML frequently obtain more modest responses that are in many instances of short duration. Several mechanisms of resistance to imatinib have been described among patients that develop clinical resistance to imatinib. Point mutations in the Bcr-Abl kinase domain that impair the ability of imatinib to inhibit the kinase activity represent the leading cause of resistance. Several approaches are being pursued to overcome these mutations. In addition, many other protein kinases implicated in signaling transduction downstream Bcr-Abl play critical roles in the pathogenesis of CML, thus representing potential therapeutic targets. Multiple compounds are being screened to identify inhibitors of these kinases. This article focuses on the current state of development of new kinase inhibitors for the therapy of CML.     

Overview of second-generation tyrosine kinase inhibitors for patients with imatinib-resistant chronic myelogenous leukemia

Imatinib mesylate (Gleevec, Novartis Pharmaceuticals Corporation, East Hanover, NJ) has revolutionized the treatment of chronic myelogenous leukemia (CML) with marked improvement in survival in all three phases--chronic, accelerated, and blast. Most patients with CML now receive imatinib, which produces complete cytogenetic response in more than 80% of patients. About 10% of patients who initially respond to imatinib subsequently develop resistance. Mechanisms of imatinib resistance in CML include amplification, mutations, and additional chromosomal aberration. To date, more than 30 mutations have been identified in imatinib-resistant CML. Dasatinib and AMN107, second-generation tyrosine kinase inhibitors, are highly effective therapies for patients with CML experiencing imatinib resistance and mutation and offer new options for patients who do not achieve an optimal response to imatinib therapy. Studies found that dasatinib and AMN107 form tighter bonds, overcoming imatinib resistance and producing complete hematologic and cytogenetic remissions. Long-term observations are needed to determine the effectiveness of the treatment. Primary care providers need to follow patients receiving first- or second-generation tyrosine kinase inhibitors because unforeseen toxicity may surface, requiring accurate assessment, evaluation, and management. Oncology nurses will be actively involved in the symptom management of patients. Providing guidelines for symptom management and advanced knowledge of specific test results for monitoring CML may increase positive outcomes.     

Stem Cell Transplantation in Patients With Chronic Myelogenous Leukemia: When Should It Be Used?

Hematopoietic stem cell transplantation has been a cornerstone of therapy for chronic myelogenous leukemia (CML) for more than 15 years and is still a standard treatment option for patients with CML. The advent of imatinib mesylate, an inhibitor of the molecular defect driving CML, the BCR-ABL tyrosine kinase, has rewritten treatment algorithms for this disease and has shifted focus away from allografting. Despite advances in stem cell transplantation, such as broader availability with the use of modified conditioning regimens, use of allografting has diminished. Also, the nearly universal patient exposure to imatinib or other kinase inhibitors before transplantation may affect the biology of the disease that is currently being treated with an allograft and ultimately may affect outcomes. Exceedingly high rates of meaningful and stable response with longer follow-up continue to drive enthusiasm for imatinib use, and understanding of resistance mechanisms has driven rapid investigation of second-generation tyrosine kinase inhibitors to address imatinib failure and suboptimal response. In most patients, imatinib reduces CML to a minimal residual disease state in which options to further deepen remission, such as immunotherapy, are sought; monitoring techniques and interpretation of response advance in parallel to meet demands; and uncertainty remains as a new natural history of CML is defined in an era of kinase inhibitor therapy. This review summarizes the state of transplant and nontransplant therapy for CML and discusses the decision making for patients with an aim to optimize the use of our best therapies for CML in an era of uncertainty.     

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.     

Utility of Therapeutic Drug Monitoring of Imatinib,Nilotinib, and Dasatinib in Chronic Myeloid Leukemia: A Systematic Review and Meta-analysis

PurposeThis study examined the utility of therapeutic drug monitoring (TDM) of imatinib, nilotinib, and dasatinib in adult patients with chronic-phase chronic myeloid leukemia (CML). TDM in CML entails the measurement of plasma tyrosine kinase inhibitor (TKI) concentration to predict efficacy and tolerability outcomes and to aid in clinical decision making. TDM was to be deemed useful if it could be used for predicting the effectiveness of a drug and/or the occurrence of adverse reactions. It was expected that the findings from the present study would allow for the definition of a therapeutic range of each TKI.MethodsA systematic review of studies reporting trough TKI levels (C_min) and clinical outcomes was performed. We included randomized clinical trials, nonrandomized controlled studies, interrupted time series studies, and case series studies that provided information about plasma levels of imatinib, nilotinib, or dasatinib and relevant clinical end points in adult patients with chronic-phase CML treated with the corresponding TKI as the single antiproliferative therapy. Meta-analyses, Student t tests, and receiver operating characteristic analyses were performed to detect mean differences between groups of patients with or without: (1) the achievement of major molecular response and (2) adverse reactions.FindingsA total of 38 studies (28 for imatinib, 7 for nilotinib, and 3 for dasatinib) were included in the systematic review. TDM was found useful in predicting the efficacy of imatinib, with a C_min cutoff value of 1000 ng/mL, consistent with guideline recommendations. We suggest a therapeutic range of imatinib at a C_min of 1000–1500 ng/mL because higher concentrations did not increase efficacy. The findings from the rest of the comparisons were inconclusive.ImplicationsTDM is useful in predicting the efficacy of imatinib in CML. Further research is needed to determine its validity with nilotinib and dasatinib.     

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.