Cytogenetics in acute leukemia

The G⁵¹⁶T CYP2B6 germline polymorphism affects the risk of acute myeloid leukemia and is associated with specific chromosomal abnormalities

The etiology of acute myeloid leukemia (AML) underlies the influence of genetic variants in candidate genes. The CYP2B6 enzyme detoxifies many genotoxic xenobiotics, protecting cells from oxidative damage. The CYP2B6 gene is subjected to a single-nucleotide polymorphism (G⁵¹⁶T) with heterozygotes (GT) and homozygotes (TT) presenting decreased enzymatic activity. This case-control study aimed to investigate the association of CYP2B6 G⁵¹⁶T polymorphism with the susceptibility of AML and its cytogenetic and clinical characteristics. Genotyping was performed on 619 AML patients and 430 healthy individuals using RCR-RFLP and a novel LightSNip assay. The major finding was a statistically higher frequency of the variant genotypes (GT and TT) in patients compared to the controls (GT:38.8% vs 29.8% and TT:9.3% vs 5.3% respectively) (p<0.001). More specifically, a significantly higher frequency of GT+TT genotypes in de novo AML patients (46.6%) and an immensely high frequency of TT in secondary AML (s-AML) (20.5%) were observed. The statistical analysis showed that the variant T allele was approximately 1.5-fold and 2.4-fold higher in de novo and s-AML respectively than controls. Concerning FAB subtypes, the T allele presented an almost 2-fold increased in AML-M2. Interestingly, a higher incidence of the TT genotype was observed in patients with abnormal karyotypes. In particular, positive correlations of the mutant allele were found in patients carrying specific chromosomal aberrations [-7/del(7q), -5/del(5q), +8, +21 or t(8;21)], complex or monosomal karyotypes. Finally, a strikingly higher frequency of TT genotype was also observed in patients stratified to the poor risk group. In conclusion, our results provide evidence for the involvement of the CYP2B6 polymorphism in AML susceptibility and suggest a possible role of the CYP2B6 genetic background on the development of specific chromosomal aberrations.

Aberrant DNA methylation and epigenetic inactivation of hMSH2 decrease overall survival of acute lymphoblastic leukemia patients via modulating cell cycle and apoptosis

OBJECTIVE

Altered regulation of many transcription factors has been shown to play important roles in the development of leukemia. hMSH2 can modulate the activity of some important transcription factors and is known to be a regulator of hematopoietic differentiation. Herein, we investigated epigenetic regulation of hMSH2 and its influence on cell growth and overall survival of acute lymphoblastic leukemia (ALL) patients.

METHODS

hMSH2 promoter methylation status was assessed by COBRA and pyrosequencing in 60 ALL patients and 30 healthy volunteers. mRNA and protein expression levels of hMSH2, PCNA, CyclinD1, Bcl-2 and Bax were determined by real time PCR and Western blotting, respectively. The influence of hMSH2 on cell proliferation and survival was assessed in transient and stable expression systems.

RESULTS

mRNA and protein expression of hMSH2 and Bcl-2 was decreased, and that of PCNA, CyclinD1 and Bax was increased in ALL patients as compared to healthy volunteers (P<0.05). hMSH2 was inactivated in ALL patients through promoter hypermethylation. Furthermore, hMSH2 hypermethylation was found in relapsed ALL patients (85.7% of all cases). The median survival of patients with hMSH2 methylation was shorter than that of patients without hMSH2 methylation (log-rank test, P=0.0035). Over-expression of hMSH2 in cell lines resulted in a significant reduction in growth and induction of apoptosis.

CONCLUSIONS

This study suggests that aberrant DNA methylation and epigenetic inactivation of hMSH2 play an important role in the development of ALL through altering cell growth and survival.

Prognostic implications of chromosome 17 abnormalities in the context of monosomal karyotype in patients with acute myeloid leukemia and complex cytogenetics

BACKGROUND

Chromosome 17 abnormalities are associated with poor outcome in leukemias including AML. Recently, MK was introduced as an independent predictor of dismal outcome in AML. The additional prognostic effect of C17 abns in patients with MK in a CK background is not clear.

PATIENTS AND METHODS

We conducted a retrospective analysis of 1086 patients with newly diagnosed AML treated between January 1998 and December 2007. Patients received treatment with one of the institution's first-line protocols.

RESULTS

Four hundred eighty-three patients had CK. Among them, 370 patients (77%) had CK-MK, and 195 patients (53%) had CK-MK-C17 abns. Patients with CK-MK had significantly shorter OS rates compared with patients with CK without MK (4.4 vs. 8 months, respectively; P = .002). The median OS for patients with CK-C17 abns was shorter than for patients without C17 abns (4 vs. 6.1 months, respectively; P = .004). In a multivariate analysis, the presence of MK among patients with CK was identified as an independent prognostic marker for OS. In addition, presence of C17 abns had a significant negative effect on OS among patients with CK-MK (P = .04).

CONCLUSION

Among patients with CK-AML, MK was associated with poor outcomes. Additional presence of C17 abns further worsens the outcome in these particularly poor-risk patients with AML.

BAALC expression: a suitable marker for prognostic risk stratification and detection of residual disease in cytogenetically normal acute myeloid leukemia

High brain and acute leukemia, cytoplasmic (BAALC) expression defines an important risk factor in cytogenetically normal acute myeloid leukemia (CN-AML). The prognostic value of BAALC expression in relation to other molecular prognosticators was analyzed in 326 CN-AML patients (<65 years). At diagnosis, high BAALC expression was associated with prognostically adverse mutations: FLT3 internal tandem duplication (FLT3-ITD) with an FLT3-ITD/FLT3 wild-type (wt) ratio of ⩾0.5 (P=0.001), partial tandem duplications within the MLL gene (MLL-PTD) (P=0.002), RUNX1 mutations (mut) (P<0.001) and WT1mut (P=0.001), while it was negatively associated with NPM1mut (P<0.001). However, high BAALC expression was also associated with prognostically favorable biallelic CEBPA (P=0.001). Survival analysis revealed an independent adverse prognostic impact of high BAALC expression on overall survival (OS) and event-free survival (EFS), and also on OS when eliminating the effect of allogeneic stem cell transplantation (SCT) (OS^TXcens). Furthermore, we analyzed BAALC expression in 416 diagnostic and follow-up samples of 66 patients. During follow-up, BAALC expression correlated with mutational load or expression levels, respectively, of other minimal residual disease markers: FLT3-ITD (r=0.650, P<0.001), MLL-PTD (r=0.728, P<0.001), NPM1mut (r=0.599, P<0.001) and RUNX1mut (r=0.889, P<0.001). Moreover, a reduction in BAALC expression after the second cycle of induction chemotherapy was associated with improved EFS. Thus, our data underline the utility of BAALC expression as a marker for prognostic risk stratification and detection of residual disease in CN-AML.

Early gene expression of acute myeloid leukemia in response to chemotherapy

The use of gene expression arrays in the evaluation and classification of tumors is becoming increasingly important in a number of malignancies. This is a powerful technique able to disclose interpatient variance in gene expression. Such variation in gene expression may be the cause of different disease outcome and may reflect disease phenotypes or chemoresistance. Acute myeloid leukemia is a malignant disease of the bone marrow where overall long-term disease-free survival is less than 50%. The need for better disease classification and evaluation is consequently evident. Gene expression profiling in acute myeloid leukemia has, in recent years, proven able to distinguish acute myeloid leukemia subclasses and predict clinical outcome and is, as such, a promising technique for improved disease evaluation. The early detection of gene expression in response to chemotherapy may be a novel way of monitoring disease management. The immediate gene response may be an indication of whether the drug of choice is efficient in leukemic cell eradication and may early indicate the need for other therapeutic measures. Furthermore, these early alterations in gene expression could facilitate identification of new treatment targets, thereby enabling better patient care and follow-up in the future.

Protective effect of cytomegalovirus reactivation on relapse after allogeneic hematopoietic cell transplantation in acute myeloid leukemia patients is influenced by conditioning regimen

Cytomegalovirus (CMV) reactivation after allogeneic hematopoietic cell transplant (allo-HCT) has been associated with a reduced risk of relapse in patients with acute myeloid leukemia (AML). However, the influence of the conditioning regimen on this protective effect of CMV reactivation after allo-HCT is relatively unexplored. To address this, we evaluated the risk of relapse in 264 AML patients who received T cell-replete, 6/6 HLA matched sibling or 10/10 HLA matched unrelated donor transplantation at a single institution between 2006 and 2011. Of these 264 patients, 206 received myeloablative (MA) and 58 received reduced-intensity conditioning (RIC) regimens. CMV reactivation was observed in 88 patients with MA conditioning and 37 patients with RIC. At a median follow-up of 299 days, CMV reactivation was associated with significantly lower risk of relapse in patients who received MA conditioning both in univariate (P = .01) and multivariate analyses (hazard ratio, .5246; P = .006); however, CMV reactivation did not significantly affect the risk of relapse in our RIC cohort. These results confirm the protective effect of CMV reactivation on relapse in AML patients after allo-HCT reported by previous studies but suggest this protective effect of CMV reactivation on relapse is influenced by the conditioning regimen used with the transplant.

Intensive induction is effective in selected octogenarian acute myeloid leukemia patients: prognostic significance of karyotype and selected molecular markers used in the European LeukemiaNet classification

We investigated whether octogenarian patients with acute myeloid leukemia enrolled onto Cooperative Group clinical trials and treated with intensive induction therapy could be cured, and whether karyotype and selected molecular markers had any prognostic significance in these patients. Among 138 patients with cytogenetic information, normal karyotype was the most common (47.1%) followed by complex karyotype (14.5%) and sole +8 (9.4%). Among these patients, the relapse-free survival rate at 1 year was 37% and 13% at 3 years, and the respective overall survival rates were 24% and 8%. Whereas the 90 patients who survived beyond 30 days had the same relapse-free survival rates, their 1-year and 3-year overall survival rates were 36% and 11%, respectively. Of the 66 patients surviving beyond 30 days who could be classified into European LeukemiaNet genetic groups, those in the intermediate-I group had better overall survival than patients in the adverse group (P=0.01). Among patients with cytogenetically normal acute myeloid leukemia who were tested for the European LeukemiaNet-associated molecular alterations, FLT3-internal tandem duplication and NPM1 mutations, it was found that FLT3-internal tandem duplication (detected in 29% of patients) did not associate with overall survival (P=0.31), whereas NPM1 mutations (30%) were associated with a significantly longer overall survival (P=0.002). We conclude that intensive induction is effective and indicated in selected octogenarians with acute myeloid leukemia, that their overall survival varies among the European LeukemiaNet genetic groups and that NPM1 mutations may be of prognostic significance among octogenarian patients with cytogenetically normal acute myeloid leukemia.

Acute myeloid leukemia with t(16;16) (p13;q22) showing a new CBFB-MYH11 fusion transcript associated with an atypical leukemic blasts morphology

Acute myeloid leukemia (AML) cases with inv(16)(p13q22) or t(16;16)(p13;q22) are characterized by multiple CBFB-MYH11 fusion transcripts, type A being the most frequent. Rare fusion variants are frequently correlated with an atypical cytomorphology, but their biologic and prognostic significance is unclear. We report a case of acute myeloid leukemia with a balanced t(16;16)(p13;q22) and additional monosomy 13 showing a new CBFB-MYH11 fusion transcript variant. The patient also showed an atypical morphology of bone marrow blasts, since about 15% of all blasts showed bilobed nuclei but there was no pathologic eosinophilia. The biologic and prognostic implications of this rare association are discussed.

CMV serostatus still has an important prognostic impact in de novo acute leukemia patients after allogeneic stem cell transplantation: a report from the Acute Leukemia Working Party of EBMT

We analyzed the prognostic impact of donor and recipient cytomegalovirus (CMV) serostatus in 16,628 de novo acute leukemia patients after allogeneic stem cell transplantation (allo-SCT). Compared with CMV-seronegative recipients who underwent allograft from a CMV-seronegative donor, cases of CMV seropositivity of the donor and/or the recipient showed a significantly decreased 2-year leukemia-free survival (44% vs 49%, P < .001) and overall survival (50% vs 56%, P < .001), and increased nonrelapse mortality (23% vs 20%, P < .001). Both groups showed a comparable relapse incidence and 2-year probability of graft-versus-host disease. The negative prognostic effects of CMV seropositivity of the donor and/or the recipient (vs CMV seronegativity of both) were significantly stronger for acute lymphoblastic leukemia (ALL) than for acute myeloid leukemia (AML), resulting in a markedly reduced 2-year overall survival (46% vs 55% for ALL compared with 52% vs 56% for AML). The important prognostic impact of donor/recipient CMV serostatus remained in a multivariate Cox regression analysis including the other prognostic variables. We conclude that donor and/or recipient CMV seropositivity is still associated with an adverse prognosis in de novo acute leukemia patients after allo-SCT despite the implementation of sophisticated strategies for prophylaxis, monitoring, and (preemptive) treatment of CMV.

FLT3-ITD and MLL-PTD influence the expression of MDR-1, MRP-1, and BCRP mRNA but not LRP mRNA assessed with RQ-PCR method in adult acute myeloid leukemia

Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) and mixed-lineage leukemia gene-partial tandem duplication (MLL-PTD) are aberrations associated with leukemia which indicate unsatisfactory prognosis. Downstream regulatory targets of FLT3-ITD and MLL-PTD are not well defined. We have analyzed the expression of MDR-1, multidrug resistant protein-1 (MRP-1), breast cancer resistance protein (BCRP), and lung resistance protein (LRP) messenger RNA (mRNA) in relation to the mutational status of FLT3-ITD and MLL-PTD in 185 acute myeloid leukemia (AML) adult patients. The real-time quantitative polymerase chain reaction method was performed to assess the expression of the MDR-1, MRP-1, BCRP, and LRP mRNA, and the results were presented as coefficients calculated using an intermediate method according to Pfaffl's rule. Significantly higher expressions of MDR-1 mRNA were found in patients who did not harbor FLT3-ITD (0.20 vs. 0.05; p = 0.0001) and MRP-1 mRNA in patients with this mutation (0.96 vs. 0.70; p = 0.002) and of BCRP mRNA in patients with MLL-PTD (0.61 vs. 0.38; p = 0.03). In univariate analysis, the high expression of MDR-1 mRNA (≥0.1317) negatively influenced the outcome of induction therapy (p = 0.05), whereas the high expression of BCRP mRNA (≥1.1487) was associated with a high relapse rate (RR) (p = 0.013). We found that the high expression of MDR-1 (≥0.1317), MRP-1 (≥0.8409), and BCRP mRNA (≥1.1487) significantly influenced disease-free survival (DFS; p = 0.059, 0.032, and 0.009, respectively) and overall survival (0.048, 0.014, and 0.059, respectively). Moreover, a high expression of BCRP mRNA (≥1.1487) proved to be an independent prognostic factor for RR (p = 0.01) and DFS (p = 0.002) in multivariate analysis. The significant correlation between the expression of MDR-1, MRP-1, and BCRP mRNA and FLT3-ITD or MLL-PTD in AML patients requires further investigation.

Circulating T cells in patients with untreated acute myelogenous leukemia are heterogeneous and can be activated through the CD3/TCR complex

T lymphocyte defects may contribute to the immune insufficiency seen in acute myelogenous leukemia (AML). We therefore characterized the T cell system for untreated AML patients. T lymphocyte subsets were analyzed by flow cytometry for 45 AML patients. The in vitro interferon-gamma (IFNgamma) release in response to stimulation with anti-CD3 plus anti-CD28 in the presence of autologous AML cells was examined for 31 patients. The majority of circulating lymphocytes were CD3(+)T cells, and CD19(+)B cells usually constituted < 10% of the lymphocytes. Most T cells expressed the alphabeta T cell receptor (TCRalphabeta(+)), and only a minority of the cells was TCRgammadelta(+). Both CD4(+) and CD8(+)T cells were detected, the CD4:CD8 ratio showed a wide variation but was generally >1.0. The majority of CD4(+) and CD8(+)T cells were CD45RA(+) cells. The T cells could be stimulated to release IFNgamma in response to anti-CD3 plus anti-CD28 ligation even in the presence of excess autologous AML blasts, and for a subset of patients (6 of 27) these IFNgamma levels could be further increased by the novel protein kinase C (PKC) agonist PEP005. In conclusion, circulating T cells in patients with untreated AML are mainly CD4(+) or CD8(+) TCRalphabeta(+); both CD45RA(+) and CD45R0(+) can be detected, and these cells can be activated through the CD3/TCR complex even in the presence of excess AML cells. For a subset of patients T cell responsiveness can be further increased by targeting PKC and these data therefore suggest that T cell function is not inhibited in AML patients.

A method to identify new molecular markers for assessing minimal residual disease in acute leukemia patients

Acute leukemias (AL) comprise a heterogeneous group of hematologic malignancies, and individual patient responses to treatment can be difficult to predict. Monitoring of minimal residual disease (MRD) is thus very important and holds great potential for improving treatment strategies. Common MRD targets include recurrent cytogenetic abnormalities and mutations in important hematological genes; unfortunately well-characterized targets are lacking in many AL patients. Here we demonstrate a technical approach for the identification and mapping of novel clone-specific chromosomal abnormalities down to the nucleotide level. We used molecular cytogenetics, chromosome microdissection, amplification of the microdissected material, and next-generation sequencing to develop PCR-based MRD assays based on unique breakpoint sequences.

Monosomal karyotypes among 1147 Chinese patients with acute myeloid leukemia: prevalence, features and prognostic impact

A monosomal karyotype (MK), defined as ≥2 autosomal monosomies or a single monosomy in the presence of additional structural abnormalities, was recently identified as an independent prognostic factor conveying an extremely poor prognosis in patients with acute myeloid leukemia (AML). In the present study, after excluding patients with t(15;17), t(8;21), inv(16) and normal karyotypes, 324 AML patients with cytogenetic abnormalities were the main subject of analysis. The incidences of MK were 13% in patients aged 15 to 60 years and 18% in those between 15 and 88 years old. MK was much more prevalent among elderly patients (p<0.001) and was significantly associated with the presence of -7, -5, del(5q), abn12p, abn17p, -18 or 18q-, -20 or 20q- and CK (for all p<0.001 except for abn12p p=0.009), and +8 or +8q was less frequent in MK+ AML(p=0.007). No correlation was noted between monosomal karyotype and FAB subtype (p>0.05); MK remained significantly associated with worse overall survival among patients with complex karyotype (p=0.032); A single autosomal monosomy contributed an additional negative effect in OS of patients with structural cytogenetic abnormalities (P=0.008). This report presents the prevalence, feature and prognostic impact of MK among a large series of Chinese AML patients from a single center for the first time.

Rapid induction of complete molecular remission by sequential therapy with LDAC and sorafenib in FLT3-ITD-positive patients unfit for intensive treatment: two cases and review of the literature

Treatment of acute myeloid leukemia remains a therapeutic challenge. Even in younger patients with a low rate of co-morbidities less than 50% of patients can be cured. For older patients or patients with significant co-morbidities, the situation appears even worse. In patients not eligible for intensive treatment approaches - e.g. due to underlying medical conditions - therapeutic approaches remain almost exclusively palliative. However, even with less intense treatment approaches, temporary remission can be achieved and this contributes to prolonged survival and improved quality of life of the respective patient. Targeted therapies have been widely used as palliative treatment in- and outside clinical trials as single agents. Combination with low-dose cytarabine (LDAC) potentially improves remission rates and can be safely administered in an outpatient setting.Previous studies showed that additive hematologic toxicity of combinatory therapeutic approaches may arise from simultaneous treatment (e.g. chemotherapy plus targeted therapies). However, sequential therapies have already proven their feasibility in clinical trials. Here, we report two cases of rapid induction of complete molecular remission by sequential therapy with LDAC and sorafenib in patients unfit for intensive chemotherapy without significant long-term toxicity.

FLT3 tyrosine kinase inhibitors in acute myeloid leukemia: clinical implications and limitations

Internal tandem duplications of the FMS-like tyrosine kinase 3 (FLT3) gene are one of the most frequent gene mutations in acute myeloid leukemia (AML) and are associated with poor clinical outcome. The remission rate is high with intensive chemotherapy, but most patients eventually relapse. During the last decade, FLT3 mutations have emerged as an attractive target for a molecularly specific treatment strategy. Targeting FLT3 receptor tyrosine kinases in AML has shown encouraging results in the treatment of FLT3 mutated AML, but in most patients responses are incomplete and not sustained. Newer, more specific compounds seem to have a higher potency and selectivity against FLT3. During therapy with FLT3 tyrosine kinase inhibitors (TKIs) the induction of acquired resistance has emerged as a clinical problem. Therefore, optimization of the targeted therapy and potential treatment options to overcome resistance is currently the focus of clinical research. In this review we discuss the use and limitations of TKIs as a therapeutic strategy for the treatment of FLT3 mutated AML, including mechanisms of resistance to TKIs as well as possible novel strategies to improve FLT3 inhibitor therapy.

Genomic and epigenomic landscapes of adult de novo acute myeloid leukemia

BACKGROUND

Many mutations that contribute to the pathogenesis of acute myeloid leukemia (AML) are undefined. The relationships between patterns of mutations and epigenetic phenotypes are not yet clear.

METHODS

We analyzed the genomes of 200 clinically annotated adult cases of de novo AML, using either whole-genome sequencing (50 cases) or whole-exome sequencing (150 cases), along with RNA and microRNA sequencing and DNA-methylation analysis.

RESULTS

AML genomes have fewer mutations than most other adult cancers, with an average of only 13 mutations found in genes. Of these, an average of 5 are in genes that are recurrently mutated in AML. A total of 23 genes were significantly mutated, and another 237 were mutated in two or more samples. Nearly all samples had at least 1 nonsynonymous mutation in one of nine categories of genes that are almost certainly relevant for pathogenesis, including transcription-factor fusions (18% of cases), the gene encoding nucleophosmin (NPM1) (27%), tumor-suppressor genes (16%), DNA-methylation-related genes (44%), signaling genes (59%), chromatin-modifying genes (30%), myeloid transcription-factor genes (22%), cohesin-complex genes (13%), and spliceosome-complex genes (14%). Patterns of cooperation and mutual exclusivity suggested strong biologic relationships among several of the genes and categories.

CONCLUSIONS

We identified at least one potential driver mutation in nearly all AML samples and found that a complex interplay of genetic events contributes to AML pathogenesis in individual patients. The databases from this study are widely available to serve as a foundation for further investigations of AML pathogenesis, classification, and risk stratification. (Funded by the National Institutes of Health.).

Molecular prognostic factors in cytogenetically normal acute myeloid leukemia

Chromosomal abnormalities are detected in 50-60% of patients with acute myeloid leukemia (AML) and are important predictors of prognosis and risk of relapse. The remaining patients, those with cytogenetically normal AML, are a seemingly homogeneous group that in fact consists of subsets of patients with distinct clinical outcomes. This heterogeneity is likely related to acquired gene mutations, as well as altered miRNA and gene-expression profiles, which occur within the group. The identification of recurrent molecular abnormalities has improved prognostication and provided insight into mechanisms of leukemogenesis for patients with cytogenetically normal AML, as well as led to the discovery of novel therapeutic targets. As the number of mutations continues to expand, bioinformatic algorithms that allow for integration of multiple markers will be necessary to provide optimal care for patients with this disease.

Characterization of chromosome 11 breakpoints and the areas of deletion and amplification in patients with newly diagnosed acute myeloid leukemia

Chromosome 11 abnormalities are found in many hematological malignancies. In acute myeloid leukemia (AML), a proto-oncogene MLL (11q23.3) is frequently altered. However, rearrangements involving other regions of chromosome 11 have been reported. Therefore, we have characterized the chromosome 11 breakpoints and common deleted and amplified areas in the bone marrow or peripheral blood cells of newly diagnosed patients with AML. Using molecular-cytogenetic methods (multicolor fluorescence in situ hybridization (mFISH), multicolor banding (mBAND), microarrays, and FISH with bacterial artificial chromosome (BAC) probes, chromosome 11 abnormalities were delineated in 54 out of 300 (18%) newly diagnosed AML patients. At least 36 different chromosome 11 breakpoints were identified; two were recurrent (11p15.4 in the NUP98 gene and 11q23.3 in the MLL gene), and three were possibly nonrandom: 11p13 (ch11:29.31-31.80 Mb), 11p12 (ch11:36.75-37.49 Mb) and 11q13.2 (68.31-68.52 Mb). One new MLL gene rearrangement is also described. No commonly deleted region of chromosome 11 was identified. However, some regions were affected more often: 11pter-11p15.5 (n = 4; ch11:0-3.52 Mb), 11p14.1-11p13 (n = 4; ch11:28.00-31.00 Mb) and 11p13 (n = 4; ch11:31.00-31.50 Mb). One commonly duplicated (3 copies) region was identified in chromosomal band 11q23.3-11q24 (n = 9; ch11:118.35-125.00 Mb). In all eight cases of 11q amplification (>3 copies), only the 5' part of the MLL gene was affected. This study highlights several chromosome 11 loci that might be important for the leukemogeneic process in AML.

New recurrent balanced translocations in acute myeloid leukemia and myelodysplastic syndromes: cancer and leukemia group B 8461

Acquired chromosome abnormalities in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are among the most valuable determinants of diagnosis and prognosis. In search of new recurrent balanced translocations, we reviewed the Cancer and Leukemia Group B (CALGB) cytogenetics database containing pretreatment and relapse karyotypes of 4,701 adults with AML and 565 with MDS who were treated on CALGB trials. We identified all cases with balanced structural rearrangements occurring as a sole abnormality or in addition to one other abnormality, excluded abnormalities known to be recurrent, and then reviewed the literature to determine whether any of what we considered unique, previously unknown abnormalities had been reported. As a result, we identified seven new recurrent balanced translocations in AML or MDS: t(7;11)(q22;p15.5), t(10;11)(q23;p15), t(2;12)(p13;p13), t(12;17)(p13;q12), t(2;3)(p21;p21), t(5;21)(q31;q22), and t(8;14)(q24.1;q32.2), and additionally, t(10;12)(p11;q15), a new translocation in AML previously reported in a case of acute lymphoblastic leukemia. Herein, we report hematologic and clinical characteristics and treatment outcomes of patients with these newly recognized recurrent translocations. We also report 52 unique balanced translocations, together with the clinical data of patients harboring them, which to our knowledge have not been previously published. We hope that once the awareness of their existence is increased, some of these translocations may become recognized as novel recurring abnormalities. Identification of additional cases with both the new recurrent and the unique balanced translocations will enable determination of their prognostic significance and help to provide insights into the mechanisms of disease pathogenesis in patients with these rare abnormalities.

Translocation t(5;18)(q35;q21) as a rare nonrandom abnormality in acute myeloid leukemia

Cytogenetic abnormalities play an important role in diagnosis, classification and prognosis in acute myeloid leukemia (AML). Nevertheless, several chromosome abnormalities have not been completely determined, and their prognostic significance is currently unknown due to their low incidence and the sporadic limited data. We report a case of AML-M2 with a novel, nonrandom translocation t(5;18)(q35;q21) in order to clarify the clinical features and outcome of these patients which could be advisable for prognostic and therapeutic purposes. This translocation has been reported only once in AML. Our patient received intensive chemotherapy, but he achieved a complete remission only initially. Eighteen months post diagnosis, t(3;12)(p23;p13) was detected as a secondary abnormality to t(5;18)(q35;q21) in the progression of the disease. FISH studies confirmed the reciprocal t(5;18)(q35;q21) and demonstrated a rearrangement of ETV6 gene as a consequence of t(3;12)(p23;p13). The patient died a few days later. In conclusion, t(5;18)(q35;q21) is a rare but nonrandom abnormality in AML, found in FAB M2 subtype, possibly associated with a rather poor prognosis, while t(3;12)(p23;p13) seems to contribute to the progression of the disease. The publication of rare, nonrandom chromosome abnormalities such as t(5;18)(q35;q21) contribute to the identification of the whole spectrum of cytogenetic abnormalities in AML and their prognostic significance.

The clinical characteristics and prognostic significance of MN1 gene and MN1-associated microRNA expression in adult patients with de novo acute myeloid leukemia

This study aimed to determine the clinical characteristics and prognostic significance of the meningioma 1 (MN1) gene and MN1-associated microRNA expression in Chinese adult de novo acute myeloid leukemia (AML) patients. The expression level of MN1, microRNA-20 (miR-20a), and microRNA-181b (miR-181b) in bone marrow mononuclear cells was measured in 158 newly diagnosed AML patients and 20 cases of normal healthy donors by real-time quantitative reverse transcriptase polymerase chain reaction. All AML patients significantly overexpressed MN1 at the level of 0.01983 (P < 0.001) compared with normal controls. High MN1 expression was associated with spleen involvement (P = 0.037), NPM1 wild type (P = 0.001), lower miR-20a expression levels (P = 0.015), and higher miR-181b expression levels (P = 0.035). MiR-20a (P = 0.029) and miR-181b (P = 0.017) overexpressed in the bone marrow cells of patients with certain subtypes of AML compared with healthy donors. High MN1 expressers had lower complete remission (CR) rates and shorter overall survival (OS) within the Southwest Oncology Group classification. In multivariable models, high MN1 expression was associated with worse CR rates (P = 0.01), relapse-free survival (RFS; P = 0.02), and OS (P = 0.02); high miR-20a expression was associated with higher CR rates (P = 0.008) and longer OS (P = 0.04), whereas high miR-181b expression was associated with lower CR rates (P = 0.03), and shorter RFS (P = 0.045) and OS (P = 0.017). High MN1 expression confers worse prognosis in Chinese adult patients with de novo AML. MN1 gene and MN1-associated microRNAs provide clinical prognosis of AML patients and may refine their molecular risk classification.

Development of gene expression-based risk score in cytogenetically normal acute myeloid leukemia patients

Patients with normal karyotype represent the single largest cytogenetic group of acute myeloid leukemia (AML), with highly heterogeneous clinical and molecular characteristics. In this study, we sought to determine new prognostic biomarkers in cytogenetically normal (CN)-AML patients. A gene expression (GE)-based risk score was built, summing up the prognostic value of 22 genes whose expression is associated with a bad prognosis in a training cohort of 163 patients. GE-based risk score allowed identifying a high-risk group of patients (53.4%) in two independent cohorts of CN-AML patients. GE-based risk score and EVI1 gene expression remained independent prognostic factors using multivariate Cox analyses. Combining GE-based risk score with EVI1 gene expression allowed the identification of three clinically different groups of patients in two independent cohorts of CN-AML patients. Thus, GE-based risk score is powerful to predict clinical outcome for CN-AML patients and may provide potential therapeutic advances.

Cytogenetic abnormalities and monosomal karyotypes in children and adolescents with acute myeloid leukemia: correlations with clinical characteristics and outcome

The whole spectrum of chromosomal abnormalities and their prognostic significance in children and adolescents with acute myeloid leukemia (AML) has not been fully elucidated yet, although a considerable amount of knowledge has been gained recently. Moreover, the incidence and prognostic impact of monosomal karyotypes (MKs), which are new cytogenetic categories reported recently in adults with AML, are currently unknown for childhood and adolescent AML. In this study, we investigated the cytogenetic and clinical characteristics of 140 children and adolescents (≤21 y) with AML, and correlated their cytogenetic features with both the clinical characteristics and outcomes of our patient cohort. The most frequent cytogenetic abnormality found in our study was the t(15;17), followed by the t(8;21). Striking differences in the genetic abnormalities and French-American-British subtypes were found among infants, children, and adolescents. Of 124 cases, 15 (12.1%) met the criteria of the MK definition, and 12 of the 15 MKs (80%) were complex karyotypes. Of 124 cases, 27 (21.8%) had cytogenetic abnormalities sufficient to be diagnosed as AML with myelodyspastic sydrome-related features. As expected, patients with the t(15;17) had the most favorable outcomes, whereas patients with 11q23 rearrangements and monosomy 7 had the worst outcomes. These data expand our knowledge by providing novel insights into the cytogenetic features and their correlations with clinical characteristics and outcomes in childhood and adolescent AML.

Meningioma 1 (MN1) expression: refined risk stratification in acute myeloid leukemia with normal cytogenetics (CN-AML)

Prognostic stratification of cytogenetic normal acute myeloid leukemia (CN-AML) is an area of active research. The aim of this study was to determine the prognostic importance of the meningioma 1 (MN1) gene expression levels in CN-AML. One hundred patients with CN-AML were diagnosed; MN1 expressions were analyzed using quantitative real-time polymerase chain reaction. High expressions were detected in 48 (48%) patients (expression range: 2.35-31.99, mean: 13.9 ± 8.49) in comparison with 52 (52%) patients with low expression (expression range: 0.02-2.3, mean: 0.68 ± 0.77). The course of the disease in patients with high MN1 expression was unfavorable. Patients with high MN1 expression was associated with significant low complete remission rate (62.5 vs. 8.4%, high vs. low MN1, P = 0.001) and high mortality rate (75% vs. 46.1, P = 0.03). AML patients with high MN1 expression tended to be refractory (37.5 vs. 19.2%, P = 0.00) and relapse risk (54.1 vs. 23%, P = 0.02). Multivariable analysis confirmed high MN1 expression as an independent risk factor for disease-free survival and overall survival. In conclusion, MN1 overexpression independently predicts bad clinical outcome in CN-AML patients.

Allo-HSCT for acute leukemia of ambiguous lineage in adults: the comparison between standard conditioning and intensified conditioning regimens

Knowledge concerning the clinical and biological characteristics of acute leukemia of ambiguous lineage (ALAL) is limited so that there has been a lack of uniformity in treatment. In this report, we retrospectively investigated the effect of intensified conditioning on adult ALAL undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). A total of 59 patients with ALAL (male in 37 cases and female in 22 cases) were consecutively enrolled in the data analyses. Twenty-four patients received the standard conditioning (total body irradiation (TBI) + cyclophosphamide (CY) or busulfan + CY protocol) and 35 received the intensified conditioning (TBI + CY + etoposide or fludarabine + cytarabine plus TBI + CY + etoposide protocol). Five-year transplant-related mortality was 17.6 ± 9.6 % and 25.5 ± 8.0 %, the 5-year overall survival (OS) post-transplantation was 23.8 ± 8.9 % and 64.0 ± 8.4 %, disease-free survival was 16.7 ± 7.6 % and 55.8 ± 9.4 %, the 5-year cumulative incidence of relapse was 80.8 ± 8.5 % and 28.8 ± 9.9 %, respectively, in the standard and the intensified group (P = 0.380, P = 0.029, P = 0.005, and P < 0.001). Both univariate and multivariate analysis indicated that the intensified conditioning regimen and acute graft-versus-host disease were favorable factors to reduce the relapse. The younger patients, patients with CR at the time of transplantation, and the intensified conditioning regimen were favorable factors to elevate the survival. In conclusion, intensified conditioning regimens followed by allo-HSCT might improve long-term survival and decrease relapse of leukemia in adult ALAL compared to the standard conditioning regimens.

Relative mitochondrial priming of myeloblasts and normal HSCs determines chemotherapeutic success in AML

Despite decades of successful use of cytotoxic chemotherapy in acute myelogenous leukemia (AML), the biological basis for its differential success among individuals and for the existence of a therapeutic index has remained obscure. Rather than taking a genetic approach favored by many, we took a functional approach to ask how differential mitochondrial readiness for apoptosis ("priming") might explain individual variation in clinical behavior. We found that mitochondrial priming measured by BH3 profiling was a determinant of initial response to induction chemotherapy, relapse after remission, and requirement for allogeneic bone marrow transplantation. Differential priming between malignant myeloblasts and normal hematopoietic stem cells supports a mitochondrial basis to the therapeutic index for chemotherapy. BH3 profiling identified BCL-2 inhibition as a targeted strategy likely to have a useful therapeutic index. BH3 profiling refines predictive information provided by conventional biomarkers currently in use and thus may itself have utility as a clinical predictive biomarker. PAPERCLIP:

Minimal residual disease detectable by quantitative assessment of WT1 gene before allogeneic stem cell transplantation in patients in first remission of acute myeloid leukemia has an impact on their future prognosis

Overall 42 patients (pts) transplanted in hematological CR1 were retrospectively analyzed. Median follow-up was 15 months (range 2-77). The expression of WT1 gene was measured according to the European Leukaemia Net recommendations. At the time of allogeneic stem cell transplantation (allo-SCT) 29 pts were WT1-negative and 13 pts were WT1-positive. In the univariate analysis, significantly better results were observed in the group of WT1 neg in terms of progression-free survival (in three yr 77% vs. 27%, p = 0.001). In multivariate analysis, the only significant feature in terms of better OS was WT1 negativity (p = 0.029). Our results show that minimal residual disease status measured by quantitative assessment of WT1 gene in acute myeloid leukemia pts in CR1 significantly affects their future prognosis after allo-SCT.

Treatment breakthroughs for the management of acute myeloid leukemia

SUMMARY Although there has been substantial improvement in the survival of younger patients with acute myeloid leukemia (AML) since the 1970s, over the past two decades subsequent gains have been modest. Survival rates in older patients with AML remain dismal and have seen minimal change since the advent of modern induction chemotherapy. However, over the past decade, there has been a dramatic increase in the development of new therapies that have promising potential to further improve survival in both older and younger patients with AML. In this review, we will examine recent and ongoing breakthroughs in genetic discovery and gene profiling, intensification of induction chemotherapy, the development of novel agents, the management of older adults and allogeneic hematopoietic cell transplantation. We will also discuss exciting advances in the management of acute promyelocytic leukemia; a disease that is now imminently curable.

Prognostic significance of flow cytometric minimal residual disease assessment after the first induction course in Chinese childhood acute myeloid leukemia

Flow cytometry based minimal residual disease (MRD) was evaluated for outcome prediction in childhood acute myeloid leukemia (AML). The median levels of MRD in relapsed and nonrelapsed patients were different after the first induction (0.64% vs. 0.18%, P=0.030). A cutoff level of ≥ 0.25% after the first course of induction was correlated with a high risk of relapse in both univariate analysis (5-year cumulative incidence of relapse: 66.8% vs. 21.2%, P=0.002) and multivariate analyses (hazard ratio: 3.70, 95% CI, 1.23-11.08, P=0.020). Our results showed that MRD level after the first induction therapy provides important information for risk assessment in childhood AML.

inv(16)/t(16;16) acute myeloid leukemia with non-type A CBFB-MYH11 fusions associate with distinct clinical and genetic features and lack KIT mutations

The inv(16)(p13q22)/t(16;16)(p13;q22) in acute myeloid leukemia results in multiple CBFB-MYH11 fusion transcripts, with type A being most frequent. The biologic and prognostic implications of different fusions are unclear. We analyzed CBFB-MYH11 fusion types in 208 inv(16)/t(16;16) patients with de novo disease, and compared clinical and cytogenetic features and the KIT mutation status between type A (n = 182; 87%) and non-type A (n = 26; 13%) patients. At diagnosis, non-type A patients had lower white blood counts (P = .007), and more often trisomies of chromosomes 8 (P = .01) and 21 (P < .001) and less often trisomy 22 (P = .02). No patient with non-type A fusion carried a KIT mutation, whereas 27% of type A patients did (P = .002). Among the latter, KIT mutations conferred adverse prognosis; clinical outcomes of non-type A and type A patients with wild-type KIT were similar. We also derived a fusion-type-associated global gene-expression profile. Gene Ontology analysis of the differentially expressed genes revealed-among others-an enrichment of up-regulated genes involved in activation of caspase activity, cell differentiation and cell cycle control in non-type A patients. We conclude that non-type A fusions associate with distinct clinical and genetic features, including lack of KIT mutations, and a unique gene-expression profile.

Cerebriform variant type of T cell prolymphocytic leukemia with complex karyotype including an additional segment at 1p36.1

We describe two patients with T cell prolymphocytic leukemia (T-PLL) who exhibited the same complex karyotype, including an additional segment at 1p36.1. One presented with secondary progression following an initial stable clinical course, and the other with typically progressive disease. Features of the cerebriform variant were identified in the peripheral blood of both patients. Aggressive symptoms, such as lymphocytosis, lymphadenopathy, pleural effusion, cutaneous involvement and hepatosplenomegaly, developed during the progressive phases. Levels of serum soluble interleukin 2 receptor increased when symptoms worsened. These patients did not have the karyotypic 14q11 abnormality and trisomy 8q that are features of non-Japanese patients. The prognoses of these patients were poor; one survived for 2 months and the other survived for 10 months after progression. A chromosomal abnormality may occur in other types of aggressive T-PLL, particularly when extramedullary infiltration is a feature.

Rapid detection of prognostically significant fusion transcripts in acute leukemia using simplified multiplex reverse transcription polymerase chain reaction

Multiplex reverse transcription polymerase chain reaction (mRT-PCR) has recently emerged as an alternative to cytogenetics. We designed and used simplified mRT-PCR system as a molecular screen for acute leukemia. Fifteen fusion transcripts were included: BCR-ABL1, PML-RARA, ZBTB16-RARA, RUNX1-RUNX1T1, CBFB-MYH11, DEK-NUP214, TCF3-PBX1, ETV6-RUNX1, MLL-AFF1, MLL-MLLT4, MLL-MLLT3, MLL-MLLT10, MLL-ELL, MLL-MLLT1, and MLL-MLLT6. A total of 121 diagnostic acute leukemia specimens were studied, comparing the mRT-PCR system with standard cytogenetics. Fifty-six cases (46.3%) had fusion transcripts revealed by our mRT-PCR assay. The concordance rate between mRT-PCR and cytogenetics was 91.7%. However, false negative results were found in three cases who have inv(16), t(4;11) or t(11;19)(q23;p13.1), respectively. Seven cryptic translocations including ETV6-RUNX1, MLL-MLLT3, MLL-MLLT4, and PML-RARA were detected. This mRT-PCR assay is a useful screening tool in acute leukemia because it provides rapid and reliable detection of clinically important chimeric transcripts. In addition, cryptic translocations provide additional genetic information that could be clinically useful.

MicroRNA control of myelopoiesis and the differentiation block in acute myeloid leukaemia

In the relatively short period of time since their discovery, microRNAs have been shown to control many important cellular functions such as cell differentiation, growth, proliferation and apoptosis. In addition, microRNAs have been demonstrated as key drivers of many malignancies and can function as either tumour suppressors or oncogenes. The haematopoietic system is not outside the realm of microRNA control with microRNAs controlling aspects of stem cell and progenitor self-renewal and differentiation, with many, if not all, haematological disorders associated with aberrant microRNA expression and function. In this review, we focus on the current understanding of microRNA control of haematopoiesis and detail the evidence for the contribution and clinical relevance of aberrant microRNA function to the characteristic block of differentiation in acute myeloid leukaemia.

Prognostic significance of the European LeukemiaNet standardized system for reporting cytogenetic and molecular alterations in adults with acute myeloid leukemia

PURPOSE

To evaluate the prognostic significance of the international European LeukemiaNet (ELN) guidelines for reporting genetic alterations in acute myeloid leukemia (AML).

PATIENTS AND METHODS

We analyzed 1,550 adults with primary AML, treated on Cancer and Leukemia Group B first-line trials, who had pretreatment cytogenetics and, for cytogenetically normal patients, mutational status of NPM1, CEBPA, and FLT3 available. We compared complete remission (CR) rates, disease-free survival (DFS), and overall survival (OS) among patients classified into the four ELN genetic groups (favorable, intermediate-I, intermediate-II, adverse) separately for 818 younger (age < 60 years) and 732 older (age ≥ 60 years) patients.

RESULTS

The percentages of younger versus older patients in the favorable (41% v 20%; P < .001), intermediate-II (19% v 30%; P < .001), and adverse (22% v 31%; P < .001) genetic groups differed. The favorable group had the best and the adverse group the worst CR rates, DFS, and OS in both age groups. Both intermediate groups had significantly worse outcomes than the favorable but better than the adverse group. Intermediate-I and intermediate-II groups in older patients had similar outcomes, whereas the intermediate-II group in younger patients had better OS but not better CR rates or DFS than the intermediate-I group. The prognostic significance of ELN classification was confirmed by multivariable analyses. For each ELN group, older patients had worse outcomes than younger patients.

CONCLUSION

The ELN classification clearly separates the genetic groups by outcome, supporting its use for risk stratification in clinical trials. Because they have different proportions of genetic alterations and outcomes, younger and older patients should be reported separately when using the ELN classification.

Molecular genetics of acute myeloid leukemia: clinical implications and opportunities for integrating genomics into clinical practice

Advances in sequencing technologies have led to the discovery of a series of mutations in a sizeable proportion of patients with acute myeloid leukemia (AML) over the last 10 years. Clinical correlative studies are now beginning to decipher the clinical importance, prevalence and potential prognostic significance of these mutations in AML but few studies have assessed the clinical implications of these mutations in a comprehensive fashion. Nonetheless, mutations in DNMT3A, TET2, and ASXL1 are emerging as important adverse prognosticators in subsets of patients with AML independent of FLT3 mutations whereas mutations in IDH2 at residue 140 are potential predictors of improved outcome in AML. Further improvements in cost, throughput, and clinical validation of second-generation sequencing technologies may allow for clinical implementation of comprehensive genetic profiling in the clinical care of AML patients.

Image cytometry-based detection of aneuploidy by fluorescence in situ hybridization in suspension

Cytogenetic abnormalities are important diagnostic and prognostic criteria for hematologic malignancies. Karyotyping and fluorescence in situ hybridization (FISH) are the conventional methods by which these abnormalities are detected. The sensitivity of these microscopy-based methods is limited by the abundance of the abnormal cells in the samples and therefore these analyses are commonly not applicable to minimal residual disease (MRD) stages. A flow cytometry-based imaging approach was developed to detect chromosomal abnormalities following FISH in suspension (FISH-IS), which enables the automated analysis of several log-magnitude higher number of cells compared with the microscopy-based approaches. This study demonstrates the applicability of FISH-IS for detecting numerical chromosome aberrations, establishes accuracy, and sensitivity of detection compared with conventional FISH, and feasibility to study procured clinical samples of acute myeloid leukemia (AML). Male and female healthy donor peripheral blood mononuclear cells hybridized with combinations of chromosome enumeration probes (CEP) 8, X, and Y served as models for disomy, monosomy, and trisomy. The sensitivity of detection of monosomies and trisomies amongst 20,000 analyzed cells was determined to be 1% with a high level of precision. A high correlation (R(2) = 0.99) with conventional FISH analysis was found based on the parallel analysis of diagnostic samples procured from 10 AML patients with trisomy 8 (+8). Additionally, FISH-IS analysis of samples procured at the time of clinical remission demonstrated the presence of residual +8 cells indicating that this approach may be used to detect MRD and associated chromosomal defects.

RUNX1 mutations are associated with poor outcome in younger and older patients with cytogenetically normal acute myeloid leukemia and with distinct gene and MicroRNA expression signatures

PURPOSE

To determine the association of RUNX1 mutations with therapeutic outcome in younger and older patients with primary cytogenetically normal acute myeloid leukemia (CN-AML) and with gene/microRNA expression signatures.

PATIENTS AND METHODS

Younger (< 60 years; n = 175) and older (≥ 60 years; n = 225) patients with CN-AML treated with intensive cytarabine/anthracycline-based first-line therapy on Cancer and Leukemia Group B protocols were centrally analyzed for RUNX1 mutations by polymerase chain reaction and direct sequencing and for established prognostic gene mutations. Gene/microRNA expression profiles were derived using microarrays.

RESULTS

RUNX1 mutations were found in 8% and 16% of younger and older patients, respectively (P = .02). They were associated with ASXL1 mutations (P < .001) and inversely associated with NPM1 (P < .001) and CEBPA (P = .06) mutations. RUNX1-mutated patients had lower complete remission rates (P = .005 in younger; P = .006 in older) and shorter disease-free survival (P = .058 in younger; P < .001 in older), overall survival (P = .003 in younger; P < .001 in older), and event-free survival (P < .001 for younger and older) than RUNX1 wild-type patients. Because RUNX1 mutations were more common in older patients and almost never coexisted with NPM1 mutations, RUNX1 mutation-associated expression signatures were derived in older, NPM1 wild-type patients and featured upregulation of genes normally expressed in primitive hematopoietic cells and B-cell progenitors, including DNTT, BAALC, BLNK, CD109, RBPMS, and FLT3, and downregulation of promoters of myelopoiesis, including CEBPA and miR-223.

CONCLUSION

RUNX1 mutations are twice as common in older than younger patients with CN-AML and negatively impact outcome in both age groups. RUNX1-mutated blasts have molecular features of primitive hematopoietic and lymphoid progenitors, potentially leading to novel therapeutic approaches.