Clonal evolution of acute myeloid leukemia from diagnosis to relapse

Based on the individual genetic profile, acute myeloid leukemia (AML) patients are classified into clinically meaningful molecular subtypes. However, the mutational profile within these groups is highly heterogeneous and multiple AML subclones may exist in a single patient in parallel. Distinct alterations of single cells may be key factors in providing the fitness to survive in this highly competitive environment. Although the majority of AML patients initially respond to induction chemotherapy and achieve a complete remission, most patients will eventually relapse. These points toward an evolutionary process transforming treatment‐sensitive cells into treatment‐resistant cells. As described by Charles Darwin, evolution by natural selection is the selection of individuals that are optimally adapted to their environment, based on the random acquisition of heritable changes. By changing their mutational profile, AML cell populations are able to adapt to the new environment defined by chemotherapy treatment, ultimately leading to cell survival and regrowth. In this review, we will summarize the current knowledge about clonal evolution in AML, describe different models of clonal evolution, and provide the methodological background that allows the detection of clonal evolution in individual AML patients. During the last years, numerous studies have focused on delineating the molecular patterns that are associated with AML relapse, each focusing on a particular genetic subgroup of AML. Finally, we will review the results of these studies in the light of Darwinian evolution and discuss open questions regarding the molecular background of relapse development.     

Transformation of diffuse large B-cell lymphoma into pre-B acute lymphoblastic leukemia: clinicopathologic features and clonal relationship

A patient with fibrosing alveolitis developed a diffuse large B-cell (DLBC) lymphoma that expressed CD20 and CD30. After an initial response, the lymphoma relapsed and was salvaged with further chemotherapy. After another remission of 3 years, a pre-B-cell acute lymphoblastic leukemia (ALL), which expressed CD10, CD19, CD22, CD79a, CD34 and terminal deoxyribonucleotidyl transferase, developed and led to death. Molecular analysis of the immunoglobulin heavy-chain gene showed that the initial lymphoma and its relapse were clonally related. At leukemic relapse, 2 clones related to the initial and relapsed lymphoma clones were present. DLBC lymphomas arise from post-follicle center B cells, whereas ALL arises from pregerminal B cells. Therefore, a direct transformation of DLBC lymphoma to ALL appears unlikely. The overall features suggest instead separate lymphoma and leukemic evolution from a common mutated B-cell precursor rather than transformation of DLBC lymphoma to ALL.     

A hybrid form of myeloid/NK-cell acute leukemia and myeloid/NK-cell precursor acute leukemia

Natural killer (NK)-cell leukemia/lymphoma is a rare entity that has been defined only in recent years. In the Revised European-American Lymphoma and World Health Organization classifications, only the mature NK-cell malignancies are included. However, at least 3 types of precursor NK-cell neoplasms have been reported in the literature. These include myeloid/NK-cell acute leukemia, myeloid/NK-cell precursor acute leukemia, and blastic NK-cell lymphoma/leukemia. These leukemias are characterized by the presence of blasts, which express CD56, in the peripheral blood, bone marrow, lymph nodes, and/or extranodal tissues. We report a case that is morphologically consistent with myeloid/NK-cell acute leukemia but immunologically is myeloid/NK-cell precursor acute leukemia. This case is unique in its cutaneous presentation without involvement of the peripheral blood. Extensive flow cytometric studies were performed on the skin biopsy and bone marrow aspirate specimens, which included many markers that had not been tested before in these entities. The clinical implications of these findings are discussed.     

急性淋巴细胞白血病患者BAALC基因表达水平也许有临床意义

目的研究急性淋巴细胞白血病（ALL）患者脑和急性白血病细胞胞浆（BAALC）基因的表达水平及其临床意义。方法57例经细胞形态学、组织化学染色及流式细胞术免疫学分型确诊的ALL患者,其中男性35例,女性22例;中位年龄23（14～66）岁。FAB分型L19例。L245例,L33例。建立实时荧光定量PCR检测BAALC基因表达的技术,并定量检测57例初发ALL患者BAALC基因的表达水平及进一步分析其与临床疗效的关系。结果57例初发ALL患者BAALC基因表达水平显著高于对照组。FAB各亚型中BAALC基因表达水平差异无统计学意义（P〉0．05）,BAALC基因表达水平的高低与初发AI上患者的免疫表型具有显著性相关．T—ALL患者和伴有髓系抗原表达ALL患者BAALC基因表达水平显著高于B—ALL（P〈0．05）和不伴有髓系抗原表达ALL患者（P〈0．01）。ALL中BAALC基因表达的水平与外周血白细胞计数（WBC）、血红蛋白（Hb）、血小板计数（Plt）及骨髓白血病细胞比例无明显相关性（P〉0．05）。BAALC基因高表达ALL患者的完全缓解率（73．3％）同低表达组f81．0％）比较差异无统计学意义（P〉0．05）,但BAALC基因高表达患者1年复发率（81．8％）明显高于低表达组（44．1％）（P〈0．05）。结论BAALC基因高表达提示可能是ALL患者一个不良预后因素,检测ALL患者BAALC基因表达水平可能有助于指导治疗。     

Increased expression of miR-24 is associated with acute myeloid leukemia with t(8;21)

This study was designed to learn the expression status of miR-24 and its clinical relevance in patients with acute myeloid leukemia (AML). We detected the miR-24 expression levels using real-time quantitative PCR in 84 AML patients and investigated the clinical significance of miR-24 expression in AML. There was no difference in clinical parameters between cases with miR-24 high expression and with miR-24 low expression. The frequency of miR-24 high expression was higher in patients with t(8;21) than in others (82% (9/11) versus 44% (32/72), P=0.026). The levels of miR-24 expression had no correlation with the mutations of nine genes (FLT3-ITD, NPM1, C-KIT, IDH1/IDH2, DNMT3A, N/K-RAS and C/EBPA). Meanwhile, among the group who obtained CR, the cases with miR-24 high expression had no difference in overall survival (OS) and relapse-free survival (RFS) than those with miR-24 low expression (P=0.612 and 0.665, respectively). These findings implicated that miR-24 high regulation is a common event in AML with t(8;21), and it might serve as a novel and selective therapeutic target for the treatment of AML with t(8;21).     

获得性21三体恶性血液病的临床和细胞遗传学特征

目的 分析21三体恶性血液病患者的临床及细胞遗传学特点.方法 采用骨髓直接法和(或)培养法制备染色体标本,采用R显带技术进行核型分析,并进行临床随访.结果 共发现25例患者存在21三体,其中急性髓系白血病(acute myeloid leukemia,AML)13例,占同期进行染色体检查的AML患者总数的1.5%,包括M5h6例;急性淋巴细胞(acute lymphoblastic leukemia,ALL)8例,占同期进行染色体检查的ALL患者总数的2.2%,其它类型4例.25例中13例为单纯获得性21三体,其余病例均合并其它异常.随访的19例患者的中位生存期为9个月.结论 单纯21三体在AML中以M5b多见,伴21三体异常的恶性血液病预后还存在争议.     

Prospective cytomegalovirus monitoring during first‐line chemotherapy in patients with acute myeloid leukemia

Little is known about the incidence and clinical impact of cytomegalovirus (CMV) infection in patients with acute myeloid leukemia at the time of diagnosis and during chemotherapy. The aims of the present study were to assess prospectively the incidence of active CMV infection in 69 consecutive patients with acute myeloid leukemia and to describe the outcomes of treatment. pp65 antigenemia was monitored at diagnosis, post‐induction and post‐consolidation chemotherapy, and whenever CMV reactivation was suspected. Patients with pp65 antigenemia received pre‐emptive anti‐CMV treatment. Fifty‐nine patients achieved complete remission. Baseline CMV serology results were available for 56 of the 59 patients: 52 patients (93%) were IgG positive. The overall incidence of pp65 antigenemia in patients in complete remission after chemotherapy was 35% (21/59): 9 patients after induction and 12 post‐consolidation. Sixteen of the 21 pp65‐positive patients received anti‐CMV treatment: 15 as pre‐emptive therapy and 1 for interstitial CMV pneumonitis. Five patients received no anti‐CMV treatment and did not develop CMV disease. Patients with pp65 antigenemia had more hospital admissions (2.57 vs. 2.16; P = 0.009), while patients with >10 pp65‐positive cells had more clinical complications (8/9 vs. 2/12; P = 0.002). In conclusion, patients with acute myeloid leukemia receiving chemotherapy should be monitored for active CMV infection. CMV reactivation in these patients was associated with an increased number of hospital admissions, and high levels of pp65 antigenemia were associated with more clinical complications. Controlled studies are needed to assess the relevance of pre‐emptive anti‐CMV therapy in patients with acute myeloid leukemia receiving chemotherapy. J. Med. Virol. 82: 1201–1207, 2010. © 2010 Wiley‐Liss, Inc.     

混合型急性白血病临床病理探讨并文献复习

目的：探讨混合型急性白血病的临床病理特征、诊断和鉴别诊断、治疗及预后。方法：回顾性分析1例混合型急性白血病患者的临床资料、组织病理形态、免疫组织化学染色、流式细胞学、染色体核型分析、治疗及随访结果,并回顾相关文献。结果：光镜下,颈部淋巴结活检示淋巴结基本结构被破坏,不见明显的淋巴滤泡及套区,代之以小-中等大小的比较均匀一致的异型淋巴样细胞,其细胞质较少,细胞核圆形或卵圆形,染色质比较均匀细腻,核仁不明显或偶见,核分裂象可见。免疫组织化学染色结果显示异型淋巴样细胞LCA散在较多(+),CD7弥漫较多(+),TdT弥漫较多(+),CD10弥漫较多(+),MPO散在(+);外周血涂片和骨髓涂片可见原始幼稚细胞;第一次化疗前后流式细胞学检测分别提示急性髓系白血病和急性B淋巴母细胞白血病。第一次化疗前骨髓短期培养法染色体核型分析提示46、XY、del(11q)。上述淋巴结活检形态学、免疫组织化学染色结果、外周血及骨髓涂片、骨髓流式细胞学及染色体核型分析均支持混合型急性白血病(转换型)的诊断。虽已更换不同的化疗方案,患者化疗效果不明显,反复出现肺部感染及骨髓抑制,均提示其预后比较差。结论：混合型急性白血病十分少见,一般需要结合形态学、免疫表型及细胞遗传学等检查才能做出诊断,对该病的鉴别诊断、治疗方案的选择及预后具有重要意义。     

Correlation between acute myeloid leukemia and IL-17A,IL-17F,and IL-23R gene polymorphism

Recent studies have shown that Th17 cells may be involved in the pathological process of acute myeloid leukemia. This CD4+ cell subgroup secretes highly homologous interleukin (IL)-17A and IL-17F, and also expresses IL-23 receptor (IL-23R) on the cell surface. Our study aims to investigate the relationship of IL-17A, IL-17F, and IL23R with disease susceptibility, and clarify the relationship between gene polymorphism variation and serum IL-17 level. 62 acute myeloid leukemia patients and 125 healthy controls were included in this study. Restriction fragment length polymorphism polymerase chain reaction (PCR-RFLP) was applied to analyze IL-17A (rs2275913; G-197A), IL17F (rs763780; A7488G; His161Arg), and IL-23R (rs11209026, G1142A; Arg381Gln) alleles. At the same time, enzyme-linked immunoassay analysis (ELISA) was used to test serum IL-17 level in patients. Acute myeloid leukemia patients presented higher rate of IL-17F G single mutant (RR = 4.75, P < 0.001) and GG mutation homozygote (RR = 23.01, P < 0.005). While IL-17A, IL-23R A single mutant and purified AA mutation homozygote showed no correlation with acute myeloid leukemia susceptibility. In addition, ELISA showed that serum IL-17 exhibited no significant difference between acute myeloid leukemia patients and healthy controls had (8.8 ± 7.19 pg/ml vs. 1.4 ± 0.2 pg/ml, P > 0.05). IL-17F G single mutant and GG mutation homozygote were correlated with acute myeloid leukemia susceptibility, while IL-17 gene polymorphism and serum IL-17 level were not. Furthermore, IL-17A and IL-23R gene polymorphism were not associated with acute myeloid leukemia susceptibility.     

A case report on a patient who presented with myelofibrosis,developed breast cancer with myeloid metaplasia,and finally showed immature NK-cell leukemia or AML without maturation with CD56 expression transformation in the pleura with extramedullary hematopoiesis: A 25-year course

This study reports a female patient who suffered from primary myelofibrosis at 38 years of age, breast cancer with myeloid metaplasia at 49 years of age, and pleural effusion and multiple subcutaneous nodules at 62 years of age. She was finally diagnosed with immature NK-cell leukemia or AML without maturation with CD56 expression transformation of extramedullary hematopoiesis that developed in the pleura, and died 11 months later. Atypical cells in the pleural effusion had surface markers of CD13, CD33, CD34, and CD56 using a fluorescence-activated cell sorter analysis, and were positive for myeloperoxidase, CD34, CD43, and CD56 in a cell block material using an immunohistochemical method. Megakaryocytic and erythroblastic cells were also seen in the pleural effusion.     

六例伴t(6;9)(p23;q34)急性髓细胞白血病患者的临床和实验研究

目的 探讨伴t(6;9)(p23;q34)急性髓细胞白血病(acute myeloid leukemia,AML)患者的临床和生物学特点.方法 抽取骨髓细胞按常规制备染色体标本,采用R显带技术进行核型分析;采用标准流式细胞仪和一组单抗检测白血病细胞的抗原表达;应用6号与9号全染色体涂染探针进行染色体荧光原位杂交(fluorescence in situ hybridization,FISH)分析;应用逆转录-PCR技术进行DEK/CAN融合基因和FLT3-ITD突变的检测.结果 t(6;9)易位主要见于M2和M4(M2 4例,M4 2例).所有病例的原始细胞均高表达CD13、CD33,其中4例同时表达HLA-DR、3例同时表达CD34和CD117,1例同时表达CD38,1例同时表达CD15.涂染证实6例患者均涉及6和9号染色体的易位,逆转录-PCR检测显示6例患者的DEK/CAN融合基因均为阳性,其中3例同时存在FLT-ITD突变,6例中的3例经治疗后死亡,生存期分别为3、5和6个月,其余病例仍在缓解中.结论 t(6;9)(p23;q34)为AML少见的再现性异常,伴有t(6;9)(p23;q34)易位的AML具有独特的生物学特征和临床特点,预后大多不良.     

伴11号染色体异常的急性髓系白血病的临床和细胞遗传学研究

目的 研究11号染色体异常在急性髓系白血病中的发生率及与临床和预后的关系.方法 采用R带常规显带技术进行染色体检查,对356例急性髓系白血病患者的核型进行分析.结果 356例急性髓系白血病患者中检出11号染色体异常患者34例,占9.55%;其中20例(58.8%)涉及11q23,7例11p15易位(20.6%),5例-11(14.7%),其他少见的核型改变有:+11,t(11;14).11q23中,M4、M5占70%;且有10例同时合并有其他染色体异常.30例进行正规化疗的患者,13例缓解,缓解率低于同期急性髓系白血病的总缓解率(43.3% vs64.0%);伴11q23的急性髓系白血病的缓解率低于染色体正常的急性髓系白血病患者(45% vs67%);11q23伴其他染色体异常的缓解率低于伴单纯11q23者(30% vs60%).7例涉及11p15易位患者3例缓解,2例早期复发.5例-11患者缓解2例.结论 11q23是11号染色体异常中最为常见的核型改变,且多见于急性髓系白血病的M5型,并可能与急性单核细胞白血病的发病有关;伴11号染色体异常的急性髓系白血病患者预后较差.     

Immunophenotypic, cytogenetic and clinical features of 192 AML patients in China

Immunophenotypic characterization of the leukemic cells has been widely used as a tool for diagnosis, classification and prognosis of leukaemia. A total of 192 Chinese patients with acute myeloid leukemia (AML) were immunophenotyped by flow cytometry using a panel of monoclonal antibodies. Among the 192 patients enrolled in this study, 125 cases were also subjected to karyotype analysis by G-banding technology. We found that CD33, CD13, MPO and CD117 were the most commonly expressed antigens in AML. A combination of intensive autofluorescence, both CD34⁻ and HLA-DR⁻, and high expression of CD13, CD33 and MPO had significant value for M3 diagnosis. CD14 was expressed only in M4 and M5, and both intensive positivity of CD64 and CD15 with high expression of HLA-DR may suggest great possibility for diagnosis of M5. Lymphoid markers expression was documented in 47.9% of the 192 AML cases analyzed. CD56 (26.0%) and CD7 (20.8%) were the most commonly expressed lymphoid markers in AML patients. Abnormal karyotypes were detected in 76 out of 125 (60.8%). Higher CD34 positivity was found in LymAg⁺ group (77.2%) than in LymAg⁻ group (48.0%). Our results indicate that immunophenotype analysis was useful for AML diagnosis and classification and the immunophenotype did have relevance to the abnormal cytogenetic changes and clinical features in AML.     

Formaldehyde and leukemia: Epidemiology,potential mechanisms,and implications for risk assessment

Formaldehyde is widely used in the United States and other countries. Occupational and environmental exposures to formaldehyde may be associated with an increased risk of leukemia in exposed individuals. However, risk assessment of formaldehyde and leukemia has been challenging due to inconsistencies in human and animal studies and the lack of a known mechanism for leukemia induction. Here, we provide a summary of the symposium at the Environmental Mutagen Society Meeting in 2008, which focused on the epidemiology of formaldehyde and leukemia, potential mechanisms, and implication for risk assessment, with emphasis on future directions in multidisciplinary formaldehyde research. Updated results of two of the three largest industrial cohort studies of formaldehyde‐exposed workers have shown positive associations with leukemia, particularly myeloid leukemia, and a recent meta‐analysis of studies to date supports this association. Recent mechanistic studies have shown the formation of formaldehyde‐induced DNA adducts and characterized the essential DNA repair pathways that mitigate formaldehyde toxicity. The implications of the updated findings for the design of future studies to more effectively assess the risk of leukemia arising from formaldehyde exposure were discussed and specific recommendations were made. A toxicogenomic approach in experimental models and human exposure studies, together with the measurement of biomarkers of internal exposure, such as formaldehyde‐DNA and protein adducts, should prove fruitful. It was recognized that increased communication among scientists who perform epidemiology, toxicology, biology, and risk assessment could enhance the design of future studies, which could ultimately reduce uncertainty in the risk assessment of formaldehyde and leukemia. Environ. Mol. Mutagen., 2010. Published 2009 Wiley‐Liss, Inc.     

Clonal evolution through genetic bottlenecks and telomere attrition: Potential threats to in vitro data reproducibility

Tissue cultures of immortalized human cells, also known as established cell lines, are broadly accessible and cost‐efficient tools for biomedical research. We here review potential genetic sources of systematic error in cell line experiments due to clonal evolution in vitro. In particular, the authors highlight alterations in telomere function over prolonged culture and population bottlenecks, respectively, as two commonly overlooked phenomena that can result in significant alterations in cell line genotypes over just one or a few passages in vitro. These alterations may include changes in mutation status of oncogenes and large scale chromosomal imbalances. We introduce a simple list of factors to be avoided in order to reduce the risk of data misinterpretation due to clonal evolution, including unacknowledged in vitro selection pressures, prolonged culture per se, harsh population size reductions, experiments at early phases after establishment, and the employment of cell lines not sufficiently analyzed by high resolution genetic techniques.