Homoharringtonine for the treatment of chronic myelogenous leukemia

Background: The anticancer activity of the natural alkaloid homoharringtonine (HHT) was first recognized by Chinese investigators. HHT exerts its activity through inhibition of protein synthesis and promotion of apoptosis. Methods: The authors reviewed the most relevant preclinical and clinical studies involving patients with chronic myelogenous leukemia (CML) receiving therapy with either natural HHT or omacetaxine mepesuccinate (Ceflatonin, Myelostat, CGX-653), a semisynthetic subcutaneously bioavailable form of HHT presently under development for the treatment of CML. Results: Prior to the advent of the tyrosine kinase inhibitor (TKI) imatinib mesilate, controlled clinical studies established HHT as the most active therapy in CML after failure of IFN-a for patients who were not candidates for allogeneic stem cell transplantation. Preliminary results from Phase II studies suggest that omacetaxine mepesuccinate is active in patients with imatinib-resistant CML, including those carrying the T315I mutation, which renders imatinib and second-generation TKIs ineffective. Conclusion: These encouraging results have propelled the development of several Phase II/III trials both in Europe and in the US to further delineate the activity of omacetaxine mepesuccinate in patients with CML who are resistant to TKI therapy.     

Omacetaxine mepesuccinate for the treatment of leukemia

Introduction: Omacetaxine mepesuccinate, formerly known as homoharringtonine, is a first-in-class cephalotaxine that has experienced phases of increasing and waning interest since its first use in traditional Chinese medicine. With activity being reported in patients with chronic myeloid leukemia (CML) resistant to currently available tyrosine kinase inhibitors, renewed interest has recently been generated.

Areas covered: The development of omacetaxine mepesuccinate, with emphasis on synthesis and mode of administration, is addressed. An overview on current clinical results as a single agent or within combination regimens in patients with acute myeloid leukemia (AML) and CML is given.

Expert opinion: Omacetaxine mepesuccinate has a unique mode of action and appreciable activity in AML and CML with generally mild nonhematologic toxicity. In patients with AML, results indicate a role within combination regimens in selected, possibly elderly patient populations. In CML, patients with resistance to tyrosine kinase inhibitors, especially due to the T315I mutation, are the most intensively studied. Despite successful results in some patients, single-agent therapy with omacetaxine mepesuccinate has resulted in modest results. However, upfront combination with tyrosine kinase inhibitor represents an attractive option due their differing mechanisms of action.     

Nilotinib for the treatment of Philadelphia-chromosome-positive chronic myeloid leukemia

Importance of the field: Although the introduction of imatinib revolutionized the management of chronic myeloid leukemia (CML), some patients exhibit resistance or intolerance to the drug. Nilotinib induces high and rapid rates of cytogenetic and molecular responses. With recent approval for newly diagnosed patients with chronic phase CML, the current algorithm for treatment will probably be transformed.

Areas covered in this review: This review will describe evaluations of nilotinib in all phases of CML from 1995 to the present. Early preclinical data and Phase I, Phase II and Phase III evaluations will demonstrate the role of nilotinib in newly diagnosed CML, as well as in imatinib-resistant or imatinib-intolerant disease.

What the reader will gain: Mutations in the BCR-ABL kinase domain are responsible for the majority of resistance to imatinib. In comparison with imatinib, nilotinib displays increased selectivity and potency at inhibiting proliferation of BCR-ABL expressing cells. Although several mutations, including T315I, remain resistant to nilotinib, activity in all phases of CML has been reported.

Take home message: Nilotinib induces high and rapid rates of cytogenetic and molecular response, with less progression to advanced forms of disease compared with imatinib. Considering that the rapid achievement of these clinical milestones has been associated with positive long-term outcomes, nilotinib as initial therapy in patients with CML in chronic phase represents the future in CML treatment. Longer follow-up is necessary to recognize survival advantages.     

索拉非尼治疗急性髓系白血病的研究进展

作为一种新型多激酶抑制剂,索拉非尼(sorafenib)已被美国FDA批准用于治疗肾细胞癌、肝细胞癌和分化甲状腺癌。而近年来的研究显示通过抑制FMS样酪氨酸激酶-3的活性,该药可发挥一定的抗白血病作用,特别是FMS样酪氨酸激酶-3近膜区的内部串联重复序列(FMS-like tyrosine kinase-3-internal tandem duplication,FLT3-ITD)突变阳性的急性髓系白血病。笔者通过查阅国内外相关文献,对其在治疗急性髓系白血病的药理作用、药物代谢动力学、临床疗效和安全性等方面的研究进展作一综述。     

针对Abl-T315I突变的Bcr-Abl蛋白激酶抑制剂的研究进展

Bcr-Abl融合基因与慢性粒细胞白血病(CML)的发病发展密切相关.直接作用于Bcr-Abl蛋白的小分子药物是目前治疗CML的重要方法,受到广泛的关注.伊马替尼作为首个上市的Bcr-Abl蛋白激酶抑制剂,在靶向治疗慢性粒细胞白血病上取得了很大成功,但Bcr-Abl基因的突变导致其出现耐药性,尤其以Abl-T315I突变的耐药程度最高.本文综述了近年正在开发中的针对Abl-T315I突变的Bcr-Abl蛋白激酶抑制剂.     

Omacetaxine mepesuccinate (synribo) – newly launched in chronic myeloid leukemia

GABA has been implicated in both the aetiology and treatment of anxiety. Tiagabine is currently the only selective GABA reuptake inhibitor available in US markets; it exerts its action via GAT-1 transporter blockade presynaptically, facilitating GABA neurotransmission. Preclinical studies and current human studies suggest tiagabine possesses anxiolytic properties. The anxiolytic properties of tiagabine have also been suggested in a number of case series, open-label studies and placebo-controlled studies in patients with different anxiety disorders. Throughout these studies, tiagabine has been reasonably tolerated; the most commonly reported adverse events include dizziness, headache and nausea. Tiagabine may be a useful addition to currently available drugs for anxiety; however, the data from small open-label investigations remain to be confirmed in larger controlled studies.     

高三尖杉酯碱联合伊马替尼治疗非Abl-T315I突变进展期慢性髓细胞白血病的临床疗效

目的 探讨高三尖杉酯碱治疗非Abl-T315I突变进展期慢性髓细胞白血病（CML）的临床疗效。方法 选取榆林市第二医院自2014年2月—2017年2月收治的非T315I突变进展期CML患者65例作为研究对象,按照双盲随机原则分成两组,对照组患者32例使用伊马替尼治疗,观察组患者33例在对照组基础上加用高三尖杉酯碱治疗,持续滴注7～11 d为1个治疗周期,每个月治疗1个周期,直至血液学指标缓解。对比两组患者治疗后细胞遗传学变化和血液学改变情况,记录两组患者毒副反应发生率情况。结果 两组患者治疗后血液学指标缓解率差异无统计学意义;观察组患者治疗12个月时遗传细胞学完全缓解率优于对照组,差异有统计学意义（P<0.05）。两组患者毒副作用差异无统计学意义。结论 高三尖杉酯碱的毒性小,对CML患者而言长期使用对血液学毒副作用较小,同时能够提升CML患者个细胞遗传学的缓解率,值得推广使用。     

Benefits and risks of ponatinib versus bosutinib following treatment failure of two prior tyrosine kinase inhibitors in patients with chronic phase chronic myeloid leukemia: a matching-adjusted indirect comparison

Objective: Comparing the benefit–risk profiles of ponatinib vs. bosutinib in third-line (3L) treatment of chronic phase chronic myeloid leukemia (CP-CML) is challenging because their pivotal trials lacked comparator arms. To characterize the overall benefit–risk profile in 3L CP-CML patients treated with bosutinib vs. ponatinib, a matching-adjusted indirect comparison (MAIC) was performed to compare efficacy outcomes and treatment duration after adjusting for trial subjects’ baseline characteristics, and tolerability was assessed with an unadjusted comparison of study-drug discontinuation.

Methods: The MAIC was performed using published data from the pivotal bosutinib trial and the most recent individual-patient-level data on file from the pivotal ponatinib trial.

Results: Responses were more frequent and durable with ponatinib (n?=?70 MAIC-adjusted) than with bosutinib (n?=?119) – complete cytogenetic response (CCyR): 61% vs. 26%; Kaplan–Meier estimate of maintaining CCyR at 4 years: 89% vs. 54%. Median treatment duration was longer with ponatinib than with bosutinib: 38.4 vs. 8.6 months. Only 9% of ponatinib patients (n?=?97 unadjusted) vs. 42% of bosutinib patients discontinued due to death, disease progression or unsatisfactory response; 19% vs. 24% discontinued due to adverse events.

Conclusions: Based on these surrogate measures of patient benefit–risk profiles, ponatinib appears to provide a net overall benefit vs. bosutinib in 3L CP-CML.     

Emerging alternatives to tyrosine kinase inhibitors for treating chronic myeloid leukemia

Introduction: BCR-ABL-directed tyrosine kinase inhibitors (TKIs) have revolutionised therapy for chronic myeloid leukemia. However, despite the availability and efficacy of this class of agents, lifelong treatment is still required in a significant proportion of patients

Areas covered: We give an overview of the currently available BCR-ABL-directed TKIs and other conventional therapies for CML. We proceed to review the current market and some of the scientific rationale for new drug development before outlining a number of novel therapies, considered broadly as immunotherapies and targeted agents. Published English-language literature was reviewed regarding currently available TKIs; clinical trials repositories were reviewed to identify novel agents recently investigated or under active study.

Expert opinion: We recommend discussion with patients and enrolment on an appropriate clinical trial where feasible. In situations where no trials are available, or if patients decline enrolment, we recommend use of an appropriate BCR-ABL directed TKI, selected on the basis of an evaluation of patient risk factors and side effect profile. Allogeneic stem cell transplant continues to have a role though this is generally limited to cases with advanced phases of disease or in cases with resistance-conferring mutations.     

The expanding role of nilotinib in chronic myeloid leukemia

Importance of the field: Several therapeutic options, including tyrosine kinase inhibitors, exist for the treatment of patients with Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML). Despite impressive results, there is room for improvement for those patients who are either resistant or intolerant to imatinib.

Areas covered in this review: An overview is given on the clinical results with nilotinib, a rationally designed second-generation tyrosine kinase inhibitor, as first- and second-line therapy in patients with Ph-positive CML. Important factors in predicting resistance to nilotinib and guiding therapeutic decisions are addressed.

What the reader will gain: Knowledge on the clinical efficacy and safety of nilotinib after imatinib failure and as first-line treatment. Point mutations in the kinase domain (KD) of BCR-ABL1 are important determinants of clinical sensitivity to currently available tyrosine kinase inhibitors, including nilotinib. Information on specific BCR-ABL1 KD mutations and safety profiles assist in therapeutic decision making.

Take home message: Nilotinib is a highly effective and well-tolerated therapeutic option in patients with Ph-positive CML after imatinib failure. Early evidence demonstrating increased efficacy has allowed expanding nilotinib to previously untreated patients in chronic phase. Insights into mechanisms of resistance to tyrosine kinase inhibitors and predictive factors for response will allow for a more individualized use of these agents.     

伊马替尼治疗Ph染色体阳性慢性粒细胞白血病的临床观察

目的:评价酪氨酸激酶抑制剂伊马替尼治疗Ph染色体阳性慢性粒细胞白血病的有效性及安全性。方法:90例慢性粒细胞白血病患者,其中慢性期67例,非慢性期23例(加速期14例,急变期9例),每天应用剂量分别为400,600mg。每周复查血常规,每3个月进行骨髓象及细胞遗传学检查,根据血象和骨髓象调整剂量。结果:观察截止时,84例(93.3%)获得血液学完全缓解;68例可评价遗传学效应,35例(51.5%)发生主要遗传学效应(慢性期30例,加速期3例,急变期2例),其中31例(88.6%)为遗传学完全缓解(慢性期27例,加速期2例,急变期2例)。11例(12.2%)患者发生严重白细胞和/或血小板减少,但可通过调整剂量控制。严重非血液学不良反应发生较少。结论:伊马替尼治疗Ph染色体阳性慢性粒细胞白血病患者疗效较好,可获得较高的完全血液学缓解率和主要细胞遗传学缓解率,起效迅速,且不良反应较少,可耐受或自行消失。     

Second line small molecule therapy options for treating chronic myeloid leukemia

Introduction: Approximately 33% of chronic myeloid leukemia (CML) patients discontinue treatment with imatinib in the long-term due to resistance and/or intolerance. Second-generation tyrosine kinase inhibitors (TKIs) (dasatinib, nilotinib, bosutinib) and third-generation (ponatinib) have added complexity to the treatment paradigm for this disease.

Areas covered: Second generation TKIs, approved as second-line treatment in all phases of the disease, are highly effective in patients resistant to and/or intolerant to imatinib and are extremely active against all the resistant BCR-ABL1 mutations, with the exception of T3151. Ponatinib, active against all BCR-ABL1 mutants including T315I, became widely used for resistant patients in all phases of disease after previous therapies. Other drugs, such as ABL001, which targets the myristoyl pocket of the ABL1 kinase, are currently in development, to offer therapeutic alternatives for resistant patients to ATP-binders.

Expert opinion: In this review, we summarize the efficacy of second line small molecules available. Specific safety profiles have emerged for each drug from sponsored clinical trials in the long-term. Stratification of patients according to comorbidities and cardiovascular risk is now needed to individualize second line treatment. Combinations of different drugs with different mechanisms of action will be used in the future to decrease the incidence of resistance.     

BCR-ABL蛋白激酶抑制剂的研究进展

伊马替尼是首个上市的BCR-ABL蛋白激酶抑制剂,在靶向治疗慢性粒细胞白血病上取得了很大成功.随着临床应用的增加,部分患者产生了耐药性.伊马替尼耐药性的产生与BCR-ABL激酶的突变有关,第二代激酶抑制剂达沙替尼和尼罗替尼能克服大部分突变产生的耐药性,但不能有效克服T315I突变.AP245234、达努塞替等针对T3151突变的BCR-ABL蛋白激酶抑制剂相继出现,展现出较好的临床应用前景.     

Gilteritinib for the treatment of relapsed and/or refractory FLT3-mutated acute myeloid leukemia

ABSTRACT

Introduction: The receptor tyrosine kinase FLT3 is the most commonly mutated gene in acute myeloid leukemia (AML). FLT3-internal tandem duplication mutations are associated with an increased risk of relapse, and a number of small molecule inhibitors of FLT3 have been developed. The highly potent and selective FLT3 kinase inhibitor gilteritinib is the first tyrosine kinase inhibitor approved as monotherapy for the treatment of relapsed and/or refractory FLT3-mutated AML.

Areas covered: We review the biology and prognostic significance of FLT3 mutations in AML and discuss the pharmacology, clinical efficacy, and toxicity profile of gilteritinib. We also summarize important differences among the various FLT3 inhibitors that are currently approved or under development and highlight areas of ongoing research.

Expert opinion: Gilteritinib has been shown to improve survival compared to salvage chemotherapy in relapsed and/or refractory FLT3-mutated AML. Gilteritinib is orally available with a favorable toxicity profile and as such is quickly becoming the standard of care for this patient population. Ongoing clinical trials are evaluating gilteritinib in combination with frontline chemotherapy, in combination with other agents such as venetoclax and azacitidine for patients who are ineligible for standard induction therapy, and as a maintenance agent.     

小分子Bcr-Abl激酶抑制剂在Ph+白血病中的研究进展

Bcr-Abl(breakpoint cluster region-Abelson)是一种异常的融合蛋白,与费城染色体(Philadelphia chromosome,Ph)阳性白血病紧密相关.作为全球十大恶性肿瘤之一,白血病严重危害着人们的健康.因此,Bcr-Abl是治疗Ph+白血病比较理想的靶点.本文简单介绍了Bcr-Abl的结构、致病机制,并归纳了小分子Bcr-Abl激酶抑制剂的研发现状.     

Intolerance to tyrosine kinase inhibitors in chronic myeloid leukemia: the possible role of ponatinib

Introduction: In spite of the proven efficacy of the tyrosine kinase inhibitor (TKI), imatinib, in chronic myeloid leukemia (CML), many patients develop intolerance and discontinue therapy in the long-term. Second-generation TKIs (dasatinib, nilotinib, bosutinib) and the third-generation TKI, ponatinib, have added opportunities but also complexity in the settings of CML treatment.

Areas covered: Different definitions of intolerance have been used through several clinical trials, making the published data non homogenous. In most cases, only the severity of acute adverse events (AEs), graded by conventional scales such as Common Terminology Criteria for Adverse Events, was reported. Limited attention to long-term events or more in general, to the impact of AEs on patient quality of life (QoL), remains a problem. Ponatinib is active against all BCR-ABL1 mutants, including T315I, and is widely used to treat patients who developed resistance to other TKIs in any CML phase; however, only limited data is available on the possible role of ponatinib for intolerant patients.

Expert opinion: We review the different definitions of intolerance used in sponsored trials and in clinical practice, and we discuss how such definitions impact on the management of AEs. We summarize how to evaluate QoL during treatment with TKIs and how to include ponatinib among possible option for intolerant patients.     

Bcr-Abl tyrosine kinase inhibitors: a patent review

Introduction: Breakpoint cluster region Abelson (Bcr-Abl) tyrosine kinase (TK) is a constitutively activated cytoplasmic TK and is the underlying cause of chronic myeloid leukemia (CML). To date, imatinib represents the frontline treatment for CML therapy. The development of resistance has prompted the search for novel Bcr-Abl inhibitors.

Areas covered: This review presents a short overview of drugs already approved for CML therapy and of the compounds that are in clinical trials. The body of the article deals with Bcr-Abl inhibitors patented since 2008, focusing on their chemical features.

Expert opinion: The search for Bcr-Abl inhibitors is very active. We believe that a number of patented compounds could enter clinical trials and some could be approved for CML therapy in the next few years. Overall, Bcr-Abl inhibitors constitute a very appealing research field that can be expected to expand further.     

Treatment options for chronic myeloid leukemia

Introduction : The bcr-abl tyrosine kinase inhibitors (TKIs) are the cornerstone treatment for chronic myeloid leukemia (CML). However, there are many topics related to therapy that remain debated.

Areas covered : The aim of this paper is to give the reader a comprehensive review of how to treat CML at diagnosis, how to monitor the disease and a brief read of special populations and case scenarios. It describes the first-line (imatinib) and second-line (nilotinib and dasatinib) TKIs currently used for the treatment of CML, including landmark studies proving their efficacy, side effect profile, dosage and use in special populations. It also reviews the current guidelines regarding treatment and monitoring of the disease while on TKIs, along with an overview of treatment in advanced stages, the role of allogeneic stem cell transplantation and investigational drugs.

Expert opinion : Although imatinib represented a mayor therapeutic advancement over conventional chemotherapy, second-generation TKIs offer higher rates of optimal response and should be used as the frontline therapy. Patients with the T315I mutation carry a worse prognosis and should be offered allogeneic stem cell transplantation. The treatment in advanced stages of CML remains suboptimal and bench, translational and clinical research is encouraged.     

Bcr-AblT315I突变慢性髓系白血病靶向治疗的研究进展

慢性髓细胞白血病(chronic myeloid leukemia,CML)是一种自我更新的造血干细胞恶性增殖肿瘤.第一代酪氨酸激酶抑制剂伊马替尼的问世,为慢性髓细胞白血病患者带来了福音,但随之后来的耐药是一个巨大的挑战,尤其是Bcr-AblT315I突变引发的耐药程度最高.目前已有多种针对T315I突变的靶向治疗药物的研究,包括已上市的Ponatinib等,本文就近年来针对T315I突变的靶向治疗药物做一综述.