APL的发病分子机制和治疗进展

急性前髓细胞性白血病(APL)是急性髓细胞样白血病(AML)的一个亚型,它的分子生物学特征为95%的患者有15号染色体前髓细胞性白血病基因(PML)与17号染色体视黄酸受体(RARα)基因的融合易位表达.维甲酸(ATRA)单药治疗能使APL患者达90%的缓解率,化疗药物与ATRA的联合应用更能降低患者复发率,改善生存;三氧化二砷(ATO)能使复发患者缓解率达到90%.这篇文章主要综述APL的发病分子机制和治疗进展.     

异基因造血干细胞移植治疗耳道复发的急性早幼粒细胞白血病一例并文献复习

目的:探讨急性早幼粒细胞白血病(APL)髓外复发的相关因素及治疗。方法:对1例APL缓解后耳道复发患者的临床资料进行回顾性分析,并复习相关文献。结果:患者2015年8月诊断为APL(低危型),经诱导后达完全缓解,随后进行巩固、维持治疗,并多次行腰椎穿刺术及椎管内注射化疗药物预防中枢神经系统白血病。2017年3月发现左外耳道新生物,活检确诊外耳道髓系肉瘤,示髓外复发。随后出现骨髓复发。经诱导巩固化疗后行异基因造血干细胞移植,存活至今。结论:对于髓外复发的急性早幼粒细胞白血病,其预后较差,异基因造血干细胞移植治疗有较好疗效。     

急性前髓细胞性白血病细胞诱导分化实验的研究进展

急性前髓细胞性白血病或急性早幼粒细胞白血病（APL）是一种特殊类型的血液系统恶性克隆性疾病,其特点是异常早幼粒细胞无限增殖伴分化受阻,是白血病中最危重的一种类型。95%以上的APL患者具有（t15;17）染色体异常,形成PML/RAR融合基因,几乎存在于所有的APL细胞中,成为APL细胞的一个特异性标志,是APL发病重要分子基础。自从全反式维甲酸（ATRA）成功用于临床诱导APL分化以来,对诱导分化剂的作用机制的研究已取得很大的进展。本文主要对APL细胞遗传学和分子生物学特征、发病机制、诱导分化机制、分化后细胞表型变化等方面对APL细胞诱导分化实验的研究进展进行综述。     

浅议与APL预后密切相关的因子

急性早幼粒细胞白血病(APL)是急性髓系白血病(AML)的一种特殊亚型。近年来随着全反式维甲酸和三氧化二砷的靶向治疗日益规范化,APL的预后已很大程度上得到提高,成为AML中预后最好的亚型,但仍有15%的患者发生复发。越来越的学者致力于研究影响APL预后的因素,以往很多人们关注过的因子在近来的研究中也发现在APL中起着重要的作用,如FLT3、CD56、Fas等,以及新近证实的一些特殊基因的表达也影响着APL的预后,BAALC低表达与APL预后正相关,与其相反Ets相关基因(ERG)高表达与APL预后负相关。在此本文总结了近年来人们在APL预后研究的进展,这些因素的发现,使人们对APL发病机制有了更深一层的了解,便于临床上早期对APL患者进行危险分层,对高风险的APL患者采用个体化治疗,也可成为日后治疗APL的新靶点。     

白血病致病基因产物靶向治疗: 从急性早幼粒到其他类型白血病

近20年来, 上海血液学研究所应用全反式维甲酸(ATRA)作为分化诱导剂治疗急性早幼粒细胞性白血病(APL)获得了重大突破, 使肿瘤细胞逆转的设想从理论走向实践, 也使ATRA治疗APL成为肿瘤诱导分化疗法最成功的典范. 本研究组在国际上首先发现了APL变异型染色体易位t(11; 17)(q23; q21), 并克隆了APL特异的染色体易位t(15; 17), t(11; 17)和t(5; 17)所形成的PML-RARa, PLZF-RARa与NPM-RARa融合基因, 建立了APL系列转基因小鼠, 证实了其在白血病发病中的作用. 核受体共抑制物(CoR)与PML-RARa形成的复合物受ATRA调控, 而ATRA不能使PLZF-RARa与CoR形成的复合物发生解离, 不仅从分子水平阐明了ATRA治疗APL疗效的差异, 还开辟了针对细胞转录调控治疗的新途径. 从1994年起, 本研究组应用三氧化二砷(As₂O₃)治疗复发的APL取得成功, 完全缓解率可达70%~80%, 还发现As₂O₃对APL的治疗呈剂量依赖性的双重作用, 即小剂量时诱导细胞发生部分分化, 而较高剂量时诱导细胞凋亡. 进一步研究发现, As₂O₃可使PML的第160位赖氨酸与泛素样SUMO-1结合, 导致PML-RARa降解. 虽然ATRA与As₂O₃的作用靶点均为异常转录因子PML-RARa, 但前者通过针对RARa受体, 后者通过PML SUMO化后使PML-RARa致病蛋白发生降解, 进而诱导APL细胞分化或凋亡. 由于ATRA和As₂O₃作用途径不同且无交叉耐药, 最近本研究组对初发APL进行了联合用药的临床试验, 结果显示, 在随访18个月后, 20例接受ATRA与As₂O₃联合治疗的APL病人无一例复发, 而37例单独应用ATRA或As₂O₃的病人中有7例复发, 获得了迄今为止成人急性白血病治疗的最好疗效, 也使APL成为第一种可能被治愈的成人白血病. 白血病致病基因产物靶向疗法在APL的成功经验将扩展到其他白血病. 联合应用STI-571与砷剂治疗慢性粒细胞白血病已在临床和实验中崭露头角, 这一治疗方案是基于针对ABL异常的酪氨酸激酶活性与降解BCR-ABL融合蛋白的双重靶向作用. 在M2b型白血病中应用新型靶向降解AML1-ETO融合蛋白和降低C-KIT异常酪氨酸激酶活性的药物, 也将为该类白血病提供新的治疗方案.     

自噬与急性早幼粒细胞白血病

急性早幼粒细胞白血病(APL)是急性髓性白血病的一种亚型,其分子特征是具有t(15;17)(q22;q21)染色体易位,并形成融合肿瘤蛋白,进而阻止早幼粒细胞分化成熟。全反式维甲酸(ATRA)和三氧化二砷(ATO)作为经典的治疗APL的药物,能够通过转录调节并激活泛素-蛋白酶体通路,促进融合肿瘤蛋白降解,发挥其临床抗白血病的功效。最近的研究发现,ATRA与ATO均能够诱导APL细胞自噬,且自噬在融合肿瘤蛋白降解及诱导早幼粒细胞分化中发挥至关重要的作用。我们简要综述近年来APL的研究进展及自噬在APL治疗中的作用。     

难治性急性白血病研究现状与进展

难治性急性白血病治疗反应差,诱导缓解率低,复发率高,生存期短,因而是白血病治疗中的难题。本文从难治性急性白血病诊断标准与免疫学、细胞遗传学及分子生物学特征,多药耐药与难治性白血病,难治性急性白血病治疗现状以及治疗展望五大方面阐述了难治性急性白血病研究现状与进展。基础与初步临床研究显示中药配合化疗能够提高难治性急性白血病围化疗期临床缓解率。认为中药在提高难治性白血病临床疗效方面具有潜在临床应用前景和开发的商业价值,值得进行深入研究。     

亚砷酸诱导分化的急性早幼粒细胞白血病细胞浸润人脑膜组织的体外模拟及其分子机制研究

目的:探讨急性早幼粒细胞白血病(Acute promyelocytic leukemia,APL)合并中枢神经系统白血病的发病机制。方法:采用流式细胞术检测亚砷酸(Arsenious acid, ATO)诱导分化前后的APL细胞及人APL细胞株NB4细胞表面CD56、CXCR4的表达;用荧光染料-羧基荧光素二醋酸盐琥珀酰亚胺酯标记ATO分化的APL(APL/ATO)、NB4细胞(NB4/ATO);用微重力旋转培养法体外模拟APL细胞浸润人脑膜组织,观察组织学及超微结构。结果:ATO诱导后,APL/ATO细胞表面CXCR4的表达明显高于诱导前(35.2±9.5%vs. 18.6±4.9%);NB4/ATO细胞表面CXCR4的表达明显高于诱导前(39.6±2.6%vs. 21.0±7.3%);APL/ATO细胞表面CD56的表达明显高于诱导前(36.6±8.9%vs. 25.8±5.15%);NB4/ATO细胞表面CD56的表达明显高于诱导前(44.6±8.4%vs. 25.6±2.4%)。组织学实验结果显示对照组脑膜组织未见NB4、APL细胞浸润,实验组可见APL/ATO、NB4/ATO细胞浸润到人脑膜组织中;荧光显微镜下可见被标记的APL/ATO、NB4/ATO细胞浸润到人脑膜组织中,扫描电镜见APL/ATO、NB4/ATO细胞浸润到脑膜组织中。结论:本研究采用微重力旋转培养系统体外模拟了ATO诱导分化的异常早幼粒细胞浸润人脑膜组织,APL细胞和NB4细胞CXCR4、CD56的表达升高可能是ATO诱导治疗APL所致的中枢神经系统浸润的分子机制之一。     

急性髓系白血病的分子机制和靶向治疗

急性髓系白血病(AML)是一类具有异质性的造血系统恶性肿瘤,其分子机制涉及基因组和表观遗传学多个层面的改变.急性早幼粒细胞白血病(APL)是AML中的特殊类型,全反式维甲酸(ATRA)和亚砷酸(ATO)的联合应用使APL成为白血病靶向治疗史上最成功的范例.四十年来AML的标准化疗方案几近未变,近年来靶向新药的涌现和免疫...     

持续缓慢静脉输注三氧化二砷治疗急性早幼粒细胞白血病的临床护理效应

目的:观察持续缓慢输注三氧化二砷(As_2O_3)治疗急性早幼粒细胞白血病(APL)病人的临床护理效应。方法:对196例急性早幼粒细胞白血病患者(APL)给予持续缓慢静脉输注As_2O_3治疗,每例患者As_2O_3日治疗总量按0.16mg/kg计算,As_2O_3注射液10毫克(10 mg/支),加入5%葡萄糖500毫升(或生理盐水500毫升)静脉滴注,8-10滴/分钟,每次滴注约18-21小时,连续用药28-50天,至完全缓解(CR)。同时,注重心理护理,加强输液管理,在用药过程中严密观察药物的毒副作用和对不良反应的及时对症护理等措施。结果:177例病人完全缓解(CR),完全缓解率达90.3%。结论:应用持续缓慢静脉输注As_2O_3治疗APL,实施积极有效的护理措施是取得显著疗效的重要环节。     

ATO/ATRA/Anthracycline-Chemotherapy Sequential Consolidation Achieves Long-Term Efficacy in Primary Acute Promyelocytic Leukemia

The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (As₂O₃, ATO) has been effective in obtaining high clinical complete remission (CR) rates in acute promyelocytic leukemia (APL), but the long-term efficacy and safety among newly diagnosed APL patients are unclear. In this retrospective study, total 45 newly diagnosed APL patients received ATRA/chemotherapy combination regimen to induce remission. Among them, 43 patients (95.6%) achieved complete remission (CR) after induction therapy, followed by ATO/ATRA/anthracycline-based chemotherapy sequential consolidation treatment with a median follow-up of 55 months. In these patients, the estimated overall survival (OS) and the relapse-free survival (RFS) were 94.4%±3.9% and 94.6±3.7%, respectively. The toxicity profile was mild and reversible. No secondary carcinoma was observed. These results demonstrated the high efficacy and minimal toxicity of ATO/ATRA/anthracycline-based chemotherapy sequential consolidation treatment for newly diagnosed APL in long-term follow-up, suggesting a potential frontline therapy for APL.     

All-Trans Retinoic Acid Activity in Acute Myeloid Leukemia: Role of Cytochrome P450 Enzyme Expression by the Microenvironment

Differentiation therapy with all-trans retinoic acid (atRA) has markedly improved outcome in acute promyelocytic leukemia (APL) but has had little clinical impact in other AML sub-types. Cell intrinsic mechanisms of resistance have been previously reported, yet the majority of AML blasts are sensitive to atRA in vitro. Even in APL, single agent atRA induces remission without cure. The microenvironment expression of cytochrome P450 (CYP)26, a retinoid-metabolizing enzyme was shown to determine normal hematopoietic stem cell fate. Accordingly, we hypothesized that the bone marrow (BM) microenvironment is responsible for difference between in vitro sensitivity and in vivo resistance of AML to atRA-induced differentiation. We observed that the pro-differentiation effects of atRA on APL and non-APL AML cells as well as on leukemia stem cells from clinical specimens were blocked by BM stroma. In addition, BM stroma produced a precipitous drop in atRA levels. Inhibition of CYP26 rescued atRA levels and AML cell sensitivity in the presence of stroma. Our data suggest that stromal CYP26 activity creates retinoid low sanctuaries in the BM that protect AML cells from systemic atRA therapy. Inhibition of CYP26 provides new opportunities to expand the clinical activity of atRA in both APL and non-APL AML.     

Therapy for acute myeloid leukemia in 119 adults: a comparison of two treatment protocols

Of 119 patients with acute myeloid leukemia, 69 were treated with Adriamycin, Vincristine and Cytosine Arabinoside (Therapy 1) and 50 with Daunorubicin, Cytosine Arabinoside and 6-Thioguanine (Therapy 2) as well as a consolidation therapy. The maintenance therapy with Cytosine Arabinoside and 6-Thioguanine was the same for both groups. The complete remission rate was 44% for Therapy 1 and 68% for Therapy 2 (p less than 0.05). - The median values for remission duration were 7 and 13 months respectively (p = 0.10); for survival time the median values were 18 and 19 months. These figures show in retrospect that high remission rates can be attained through intensive induction therapy and that longer remission duration is correlated with more aggressive induction therapy. A mild form of maintenance therapy seems to have little effect on the duration of complete remission.     

FLT3 and NPM-1 mutations in a cohort of acute promyelocytic leukemia patients from India

Background:

Acute promyelocytic leukemia (APL) with t (15;17) is a distinct category of acute myeloid leukemia (AML) and is reported to show better response to anthracyclin based chemotherapy. A favorable overall prognosis over other subtypes of AML has been reported for APL patients but still about 15% patients relapse.

Methods:

This study evaluated the presence of Famus like tyrosine kinase-3 (FLT3) and nucleophosmin-1 (NPM1) gene mutations in a cohort of 40 APL patients. Bone marrow/peripheral blood samples from patients at the time of diagnosis and follow-up were processed for immunophenotyping, cytogenetic markers and isolation of DNA and RNA. Samples were screened for the presence of mutations in FLT3 and NPM1 genes using polymerase chain reaction followed by sequencing.

Results:

Frequency of FLT3/internal tandem duplication and FLT3/tyrosine kinase domain was found to be 25% and 7% respectively. We observed a high frequency of NPM1 mutation (45%) in the present population of APL patients.     

An abnormal CD34+ myeloid/CD34+ lymphoid ratio at the end of chemotherapy predicts relapse in patients with acute myeloid leukemia.

During conventional follow-up of patients with acute myeloid leukemia (AML), the emergence of cytopenias is considered to be a sign of impending relapse, and it represents an example of how leukemic hematopoiesis affects normal hemopoietic differentiation. In the present study, we have explored the possible value of the analysis of the distribution of CD34+ myeloid and CD34+ lymphoid progenitor cells in follow-up complete remission bone marrow samples from de novo AML patients as a prognostic parameter for predicting relapse. A total of 213 bone marrow samples from 36 AML patients in morphological complete remission, obtained at the end of induction, consolidation, and intensification therapy and every six months thereafter were analyzed. The normal CD34+ myeloid/CD34+ lymphoid ratio ranged between 2.4 and 8.9. In contrast, in most AML cases an abnormally high ratio (> or =10) was observed at the end of induction and consolidation therapy: 96% and 75% of cases, respectively. On the other hand, at the end of intensification, 70% of the patients displayed a normal CD34+ ratio. Patients with a myeloid/lymphoid CD34+ ratio higher than 10 at the end of intensification showed a significantly lower overall survival (median survival of 19 months versus median not reached, P = 0.05), as well as a lower disease-free survival (median of 7 months versus 30 months, P = 0.0001). Regarding sequential studies, 67% of the relapses were preceded by the re-appearance of an abnormal CD34 ratio, whereas relapse was not predicted in four patient with leukemia classified as M3 undergoing maintenance therapy. From the remaining 18 patients who are still in continuous complete remission, all except 3 cases (17%) displayed a normal CD34 myeloid/lymphoid ratio. In summary, the present study shows that the persistence at the end of chemotherapy of an abnormally high (> or =10) ratio between CD34+ myeloid and CD34+ lymphoid progenitors in the bone marrow of AML patients is associated with high risk of relapse and a shorter overall survival.