Genetic Factors in Acute Myeloid Leukemia With Myelodysplasia-Related Changes

OBJECTIVES

Acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) is a heterogeneous category with a broad range of underlying genetic abnormalities. We investigated the significance of genetic factors in a large series of AML-MRC cases.

METHODS

The morphologic findings, genetic data, and patient outcomes were assessed in 186 AML-MRC cases.

RESULTS

The median overall survival (OS) was dismal in AML-MRC patients (median, 7.6 months; 95% confidence interval, 5-10.6 months). Karyotypically normal cases and cytogenetically abnormal cases without myelodysplastic syndrome (MDS)-related cytogenetic abnormalities showed similar OS, significantly better than cases carrying MDS-related cytogenetic abnormalities. MDS-related cytogenetic abnormalities, monosomal or complex karyotype, and history of MDS or myelodysplastic/myeloproliferative neoplasm were all associated with dismal outcome.

CONCLUSIONS

AML-MRC predicts a poor prognosis. Our study supports the finding that the genetic profile plays a key role in determining prognosis in AML-MRC as defined according to the World Health Organization revised fourth edition (2017) diagnostic criteria.

The Prognostic Significance of the BMI-1 and BAALC Genes in Adult Patients with Acute Myeloid Leukemia

The aim of this work is to investigate the different expression patterns of B cell-specifics moloney murine Leukemia virus integration site-1 (BMI-1) and brain and acute leukemia, cytoplasmic (BAALC) genes, their prognostic and clinical significance in newly diagnosed cytogenetically heterogenous adult acute myeloid leukemia patients. BMI-1 and BAALC expression was detected in the bone marrow of patients using quantitative real-time reverse transcription polymerase chain reaction with cut off value set at 50th percentile for both genes. BMI-1 and BAALC overexpression was detected in 50% of cases which suggest their potential as molecular markers. A statistical significant correlation was found between BMI-1 expression with hepatomegaly (P value = 0.007), hemoglobin level-grouped (P value = 0.047) and cytogenetic risk groups (P value = 0.036). There was a statistically significant correlation between BAALC and age (P value = 0.015), lymphadenopathy (P value = 0.043), CD34 expression (P value = 0.003) and near statistical significance with FAB sub-groups (P value = 0.054). No statistical significance was noted for other hematological findings and response to treatment except for BAALC gene and treatment response (P value = 0.014). No statistical significance in overall survival and disease free survival for both genes was found. Their prospective screening in combination with other molecular markers can help refine myeloid leukemia staging and prognosis toward optimizing therapeutic interventions.

Clinical implications of recurrent gene mutations in acute myeloid leukemia

Acute myeloid leukemia (AML) is a genetically heterogeneous clonal malignancy characterized by recurrent gene mutations. Genomic heterogeneity, patients’ individual variability, and recurrent gene mutations are the major obstacles among many factors that impact treatment efficacy of the AML patients. With the application of cost- and time-effective next-generation sequencing (NGS) technologies, an enormous diversity of genetic mutations has been identified. The recurrent gene mutations and their important roles in acute myeloid leukemia (AML) pathogenesis have been studied extensively. In this review, we summarize the recent development on the gene mutation in patients with AML.

Genetic Characterization and Risk Stratification of Acute Myeloid Leukemia

The most common acute leukemia in adults is acute myeloid leukemia (AML). The pathophysiology of the disease associates with cytogenetic abnormalities, gene mutations and aberrant gene expressions. At the molecular level, the disease manifests as changes in both epigenetic and genetic signatures. At the clinical level, two aspects of AML should be taken into account. First, the molecular changes occurring in the disease are important prognostic and predictive markers of AML. Second, use of novel therapies targeting these molecular changes. Currently, cytogenetic abnormalities and molecular alterations are the common biomarkers for the prognosis and choice of treatment for AML. Finding a panel of multiple biomarkers is a crucial diagnostic step for patient classification and serves as a prerequisite for individualized treatment strategies. Furthermore, the most important way of identifying relevant targets for new treatment approaches is defining specific patterns or a spectrum of driver gene mutations occurring in AML. Then, an algorithm can be established by the use of several biomarkers, to be used for personalized medicine. This review deals with molecular alterations, risk stratification, and relevant therapeutic decision-making in AML.

Landscape of Tumor Suppressor Mutations in Acute Myeloid Leukemia

Acute myeloid leukemia is mainly characterized by a complex and dynamic genomic instability. Next-generation sequencing has significantly improved the ability of diagnostic research to molecularly characterize and stratify patients. This detailed outcome allowed the discovery of new therapeutic targets and predictive biomarkers, which led to develop novel compounds (e.g., IDH 1 and 2 inhibitors), nowadays commonly used for the treatment of adult relapsed or refractory AML. In this review we summarize the most relevant mutations affecting tumor suppressor genes that contribute to the onset and progression of AML pathology. Epigenetic modifications (TET2, IDH1 and IDH2, DNMT3A, ASXL1, WT1, EZH2), DNA repair dysregulation (TP53, NPM1), cell cycle inhibition and deficiency in differentiation (NPM1, CEBPA, TP53 and GATA2) as a consequence of somatic mutations come out as key elements in acute myeloid leukemia and may contribute to relapse and resistance to therapies. Moreover, spliceosomal machinery mutations identified in the last years, even if in a small cohort of acute myeloid leukemia patients, suggested a new opportunity to exploit therapeutically. Targeting these cellular markers will be the main challenge in the near future in an attempt to eradicate leukemia stem cells.

[CD7 expression and its prognostic significance in acute myeloid leukemia patients with wild-type or mutant CEBPA]

目的

分析CD7在初治急性髓系白血病（AML）患者中的表达和预后价值，进一步探讨CD7表达情况与CEBPA突变的相关性，明确其在CEBPA野生型和突变型AML患者中与预后的关系。

方法

回顾性分析2010年1月至2016年12月收治的298例初治AML患者（除外M₃亚型）的临床资料，在全部患者以及CEBPA野生型和突变型组中，分别比较CD7阳性（CD7⁺）和CD7阴性（CD7⁻）患者的临床特征及预后差异，并联合CD7表达情况和CEBPA突变状态初步建立新的危险分层模型。

结果

在CD7⁺组中，CEBPA单位点和双位点突变的发生率分别为10.1%和33.9%，显著高于CD7⁻组（5.3%和4.2%），差异具有统计学意义（P=0.000）。在CEBPA野生型患者中，CD7⁺组患者相较CD7⁻组患者完全缓解率低（P=0.001）、复发率高（P=0.023），而两组总生存（OS）期和无病生存（DFS）期差异无统计学意义（P值均>0.05）；在CEBPA突变患者中，CD7⁺组显示有更长的OS期（P=0.019）和DFS期（P=0.010）。根据CD7表达和CEBPA突变与否将AML患者分为三个亚组：CD7⁺伴CEBPA突变组、CD7⁻组和CD7⁺伴CEBPA野生型组。三组患者的3年OS率分别为80.2%、48.0%和30.6%（P<0.001），3年的DFS率分别为74.1%、37.4%和22.2%（P<0.001）。

结论

CD7⁺组中CEBPA突变率显著高于CD7⁻组，CD7⁺在CEBPA野生型组和突变组AML中存在截然相反的预后意义。根据CD7表达情况和CEBPA突变与否建立新的危险分层模型，有助于指导临床个体化治疗。

Identification of relapse-associated gene mutations by next-generation sequencing in low-risk acute myeloid leukaemia patients

Recommended genetic categorization of acute myeloid leukaemias (AML) includes a favourable-risk category, but not all these patients have good prognosis. Here, we used next-generation sequencing to evaluate the mutational profile of 166 low-risk AML patients: 30 core-binding factor (CBF)-AMLs, 33 nucleophosmin (NPM1)-AMLs, 4 biCEBPα-AMLs and 101 acute promyelocytic leukaemias (APLs). Functional categories of mutated genes differed among subgroups. NPM1-AMLs showed frequent variations in DNA-methylation genes (DNMT3A, TET2, IDH1/2) (79%), although without prognostic impact. Within this group, splicing-gene mutations were an independent factor for relapse-free (RFS) and overall survival (OS). In CBF-AML, poor independent factors for RFS and OS were mutations in RAS pathway and cohesin genes, respectively. In APL, the mutational profile differed according to the risk groups. High-risk APLs showed a high mutation rate in cell-signalling genes (P = 0·002), highlighting an increased incidence of FLT3 internal tandem duplication (ITD) (65%, P < 0·0001). Remarkably, in low-risk APLs (n = 28), NRAS mutations were strongly correlated with a shorter five-year RFS (25% vs. 100%, P < 0·0001). Overall, a high number of mutations (≥3) was the worst prognostic factor RFS (HR = 2·6, P = 0·003). These results suggest that gene mutations may identify conventional low-risk AML patients with poor prognosis and might be useful for better risk stratification and treatment decisions.

Mutation topography and risk stratification for de novo acute myeloid leukaemia with normal cytogenetics and no nucleophosmin 1 (NPM1) mutation or Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD)

About 25% of patients with newly diagnosed acute myeloid leukaemia (AML) have normal cytogenetics and no nucleophosmin 1 (NPM1) mutation or Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD). The prognosis and best therapy for these patients is controversial. We evaluated 158 newly diagnosed adults with this genotype who achieved histological complete remission within two cycles of induction therapy and were assigned to two post-remission strategies with and without an allotransplant. Targeted regional sequencing at diagnosis was performed and data were used to estimate their prognosis, including relapse and survival. In multivariable analyses, having wild-type or mono-allelic mutated CCAAT/enhancer-binding protein alpha (CEBPA) [hazard ratio (HR) 2·39, 95% confidence interval (CI) 1·08-5·30; P = 0·032), mutated NRAS (HR 2·67, 95% CI 1·36-5·25; P = 0·004), mutated colony-stimulating factor 3 receptor (CSF3R) (HR 2·85, 95% CI 1·12-7·27; P = 0·028) and a positive measurable residual disease (MRD)-test after the second consolidation cycle (HR 2·88, 95% CI 1·32-6·30; P = 0·008) were independently correlated with higher cumulative incidence of relapse (CIR). These variables were also significantly associated with worse survival (HR 3·02, 95% CI 1·17-7·78, P = 0·022; HR 3·62, 95% CI 1·51-8·68, P = 0·004; HR 3·14, 95% CI 1·06-9·31, P = 0·039; HR 4·03, 95% CI 1·64-9·89, P = 0·002; respectively). Patients with ≥1 of these adverse-risk variables benefitted from a transplant, whereas the others did not. In conclusion, we identified variables associated with CIR and survival in patients with AML and normal cytogenetics without a NPM1 mutation or FLT3-ITD.

Nanopore Targeted Sequencing for Rapid Gene Mutations Detection in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) clinical settings cannot do without molecular testing to confirm or rule out predictive biomarkers for prognostic stratification, in order to initiate or withhold targeted therapy. Next generation sequencing offers the advantage of the simultaneous investigation of numerous genes, but these methods remain expensive and time consuming. In this context, we present a nanopore-based assay for rapid (24 h) sequencing of six genes (NPM1, FLT3, CEBPA, TP53, IDH1 and IDH2) that are recurrently mutated in AML. The study included 22 AML patients at diagnosis; all data were compared with the results of S5 sequencing, and discordant variants were validated by Sanger sequencing. Nanopore approach showed substantial advantages in terms of speed and low cost. Furthermore, the ability to generate long reads allows a more accurate detection of longer FLT3 internal tandem duplications and phasing double CEBPA mutations. In conclusion, we propose a cheap, rapid workflow that can potentially enable all basic molecular biology laboratories to perform detailed targeted gene sequencing analysis in AML patients, in order to define their prognosis and the appropriate treatment.

Cooperation of Dnmt3a R878H with Nras G12D promotes leukemogenesis in knock-in mice: a pilot study

BACKGROUND

DNMT3A R882H, a frequent mutation in acute myeloid leukemia (AML), plays a critical role in malignant hematopoiesis. Recent findings suggest that DNMT3A mutant acts as a founder mutation and requires additional genetic events to induce full-blown AML. Here, we investigated the cooperation of mutant DNMT3A and NRAS in leukemogenesis by generating a double knock-in (DKI) mouse model harboring both Dnmt3a R878H and Nras G12D mutations.

METHODS

DKI mice with both Dnmt3a R878H and Nras G12D mutations were generated by crossing Dnmt3a R878H knock-in (KI) mice and Nras G12D KI mice. Routine blood test, flow cytometry analysis and morphological analysis were performed to determine disease phenotype. RNA-sequencing (RNA-seq), RT-PCR and Western blot were carried out to reveal the molecular mechanism.

RESULTS

The DKI mice developed a more aggressive AML with a significantly shortened lifespan and higher percentage of blast cells compared with KI mice expressing Dnmt3a or Nras mutation alone. RNA-seq analysis showed that Dnmt3a and Nras mutations collaboratively caused abnormal expression of a series of genes related to differentiation arrest and growth advantage. Myc transcription factor and its target genes related to proliferation and apoptosis were up-regulated, thus contributing to promote the process of leukemogenesis.

CONCLUSION

This study showed that cooperation of DNMT3A mutation and NRAS mutation could promote the onset of AML by synergistically disturbing the transcriptional profiling with Myc pathway involvement in DKI mice.

In Silico Genetics Revealing 5 Mutations in CEBPA Gene Associated With Acute Myeloid Leukemia

Background:

Acute myeloid leukemia (AML) is an extremely heterogeneous malignant disorder; AML has been reported as one of the main causes of death in children. The objective of this work was to classify the most deleterious mutation in CCAAT/enhancer-binding protein-alpha (CEBPA) and to predict their influence on the functional, structural, and expression levels by various Bioinformatics analysis tools.

Methods:

The single nucleotide polymorphisms (SNPs) were claimed from the National Center for Biotechnology Information (NCBI) database and then submitted into various functional analysis tools, which were done to predict the influence of each SNP, followed by structural analysis of modeled protein followed by predicting the mutation effect on energy stability; the most damaging mutations were chosen for additional investigation by Mutation3D, Project hope, ConSurf, BioEdit, and UCSF Chimera tools.

Results:

A total of 5 mutations out of 248 were likely to be responsible for the structural and functional variations in CEBPA protein, whereas in the 3′-untranslated region (3′-UTR) the result showed that among 350 SNPs in the 3′-UTR of CEBPA gene, about 11 SNPs were predicted. Among these 11 SNPs, 65 alleles disrupted a conserved miRNA site and 22 derived alleles created a new site of miRNA.

Conclusions:

In this study, the impact of functional mutations in the CEBPA gene was investigated through different bioinformatics analysis techniques, which determined that R339W, R288P, N292S, N292T, and D63N are pathogenic mutations that have a possible functional and structural influence, therefore, could be used as genetic biomarkers and may assist in genetic studies with a special consideration of the large heterogeneity of AML.

Genetic heterogeneity of cytogenetically normal AML with mutations of CEBPA

Biallelic mutations of the CCAAT/enhancer binding protein α (CEBPA) gene define a distinct genetic entity of acute myeloid leukemia (AML) with favorable prognosis. The presence of GATA2 and CSF3R mutations that are specifically associated with this subgroup but not mutated in all samples suggests a genetic heterogeneity of biCEBPA-mutated AML. We characterized the mutational landscape of CEBPA-mutated cytogenetically normal AML by targeted amplicon resequencing. We analyzed 48 biallelically mutated CEBPA (biCEBPA), 32 monoallelically mutated CEBPA (moCEBPA), and 287 wild-type CEBPA (wtCEBPA) patient samples from German AML Cooperative Group studies or registry. Targeted sequencing of 42 genes revealed that moCEBPA patients had significantly more additional mutations and additional mutated genes than biCEBPA patients. Within the group of biCEBPA patients, we identified 2 genetic subgroups defined by the presence or absence of mutations in chromatin/DNA modifiers (C), cohesin complex (C), and splicing (S) genes: biCEBPA ^CCSpos (25/48 [52%]) and biCEBPA ^CCSneg (23/48 [48%]). Equivalent subgroups were identified in 51 biCEBPA patients from the Cancer Genome Project. Patients in the biCEBPA ^CCSpos group were significantly older and had poorer overall survival and lower complete remission rates following intensive chemotherapy regimens compared with patients in the biCEBPA ^CCSneg group. Patients with available remission samples from the biCEBPA ^CCSpos group cleared the biCEBPA mutations, but most had persisting CCS mutations in complete remission, suggesting the presence of a preleukemic clone. In conclusion, CCS mutations define a distinct biological subgroup of biCEBPA AML that might refine prognostic classification of AML. This trial was registered at www.clinicaltrials.gov as #NCT00266136 and NCT01382147.

Molecular profiling of adult acute myeloid and lymphoid leukemia in a major referral center in Lebanon: a 10-year experience report and review of the literature

Recurrent genetic abnormalities confer distinct morphologic features and play a role in determining the clinical behavior, prognosis and adequate treatment of acute leukemia. In the MENA region, only one study targets the frequency of genetic modifications in AML, reporting a higher occurrence of acute promyelocytic leukemia in Lebanon. Determining the frequency of translocations and gene mutations in acute myeloid and lymphoid leukemia cases in an adult patients' population in Lebanon and comparing the resultant genetic profile with the published international molecular profile of adult acute leukemia. Laboratory results of adult patients diagnosed with AML or ALL presenting to AUBMC for genetic profiling between years 2006 until June 2016 were reviewed. Genetic profiling of AML cases in our CAP accredited molecular diagnostics laboratory consists of a validated lab developed RT-PCR for the detection of RUNX1/RUNX1T1, CBFB/MYH11, KMT2A/MLLT3, PML-RARA, and BCR-ABL and mutations in the FLT3 receptor, NPM1, c-kit and CEPBA genes. The ALL panel tests for the presence of BCR-ABL1, ETV6/RUNX1; KMT2A/AFF1, and TCF3-PBX1. We reviewed 580 AML and 175 ALL cases. In the AML cohort, the M:F ratio was 1.3:1 with a mean age of 50 years. t(15;17) was present in 7.6%, t(8;21) in 4.2%, inv(16) in 3.7%, t(9;22) in 2.2% and t(9;11) in 1.7% of cases. FLT3 mutation (ITD or TKD) was present in 25.2% of all cases and 30.1% of Cytogenetics-normal (CN) patients. Mutations of the NPM1 gene was present in 31.4% of AML cases and in 43.8% of CN patients. Double positive (NPM1+/FLT3+) cases accounted for 20% of NK patients. CEBPA and c-kit mutations were detected in 7.3% and 2.4% respectively. In the ALL cohort, the mean age was 37 years. B- and T-lymphoblastic leukemia constituted 84.6% and 15.4% of ALL cases and the M:F ratio was 1.2:1 and 2.86:1 respectively. B-ALL patients were positive for t(9;22) in 14.2%, t(4;11) in 5.4%, t(1;19) in 2.7% and t(12;21) in 1.4%. T-ALL patients were negative for translocations found in our ALL panel. A lower mean age was found in our adult leukemic Lebanese population as compared to the Western cases. Other interesting findings were the lower percentage of inv(16), lower incidence of TCF3-PBX1, and the mild increase in Philadelphia positivity in our AML cohort. In our ALL cohort, t(9;22) positivity was less than expected for adult lymphoblastic leukemia. Full molecular profiling by next generation sequencing is required for further classification of cases into prognostic categories. This study will be a baseline reference for future research and epidemiological data useful for transplant centers and oncologists both in Lebanon and the region.

Focal Adhesion Genes Refine the Intermediate-Risk Cytogenetic Classification of Acute Myeloid Leukemia

In recent years, several attempts have been made to identify novel prognostic markers in patients with intermediate-risk acute myeloid leukemia (IR-AML), to implement risk-adapted strategies. The non-receptor tyrosine kinases are proteins involved in regulation of cell growth, adhesion, migration and apoptosis. They associate with metastatic dissemination in solid tumors and poor prognosis. However, their role in haematological malignancies has been scarcely studied. We hypothesized that PTK2/FAK, PTK2B/PYK2, LYN or SRC could be new prognostic markers in IR-AML. We assessed PTK2, PTK2B, LYN and SRC gene expression in a cohort of 324 patients, adults up to the age of 70, classified in the IR-AML cytogenetic group. Univariate and multivariate analyses showed that PTK2B, LYN and PTK2 gene expression are independent prognostic factors in IR-AML patients. PTK2B and LYN identify a patient subgroup with good prognosis within the cohort with non-favorable FLT3/NPM1 combined mutations. In contrast, PTK2 identifies a patient subgroup with poor prognosis within the worst prognosis cohort who display non-favorable FLT3/NPM1 combined mutations and underexpression of PTK2B or LYN. The combined use of these markers can refine the highly heterogeneous intermediate-risk subgroup of AML patients, and allow the development of risk-adapted post-remission chemotherapy protocols to improve their response to treatment.

Clinical implications of molecular markers in acute myeloid leukemia

The recently updated World Health Organization (WHO) Classification of myeloid neoplasms and leukemia reflects the fact that research in the underlying pathogenic mechanisms of acute myeloid leukemia (AML) has led to remarkable advances in our understanding of the disease. Gene mutations now allow us to explore the enormous diversity among cytogenetically defined subsets of AML, particularly the large subset of cytogenetically normal AML. Despite the progress in unraveling the tumor genome, only a small number of recurrent mutations have been incorporated into risk-stratification schemes and have been proven to be clinically relevant, targetable lesions. We here discuss the utility of molecular markers in AML in prognostication and treatment decision making, specifically highlighting the aberrations included in the current WHO classification.

The 2016 WHO classification of acute myeloid leukemia: What the practicing clinician needs to know

In 2016 a revision of the World Health Organization (WHO) classification of acute myeloid leukemia (AML) was introduced that included changes to several disease categories. The WHO approach results in disease categories that are defined by a combination of clinical, morphologic, immunophenotypic, and genetic features in an attempt to define clinically relevant, biologic entities. This review summarizes the WHO approach as well as the priority of specific features for disease classification. Changes to specific categories, including AML with myelodysplasia-related changes, AML with mutated NPM1, AML with biallelic mutations of CEBPA and erythroleukemia are summarized. The importance of additional gene mutations as well as germline predisposition in AML is also reviewed.

Mutational spectrum and prognostic stratification of intermediate-risk acute myeloid leukemia

The mutational spectrum and prognostic stratification of intermediate-risk acute myeloid leukemia (IR-AML), which accounts for a substantial number of AML, are unclear. In order to explore the prognostic significance of the mutational spectrum in IR-AML, 106 IR-AML patients were collected from The Cancer Genome Atlas database. Sixty-two patients underwent chemotherapy-only, forty-four proceeded to allogeneic hematopoietic stem cell transplantation (allo-HSCT). Fifty-five patients had more than five recurrent genetic mutations. NPM1 had the highest mutation frequency, followed by DNMT3A, FLT3, RUNX1, IDH2, IDH1, and TET2. In all patients, allo-HSCT was an independent favorable factor for EFS and OS (P = 0.036, P = 0.001, respectively); age ≥60 years, FLT3-ITD and mutations in DNMT3A and RUNX1 were independent risk factors for survival (all P < 0.05). In the chemotherapy-only group, multivariate analysis showed that age ≥60 years was an independent risk factor for EFS and OS (P = 0.008, P = 0.017, respectively). In the allo-HSCT group, multivariate analysis indicated that MLL-PTD was an independent risk fact for EFS (P = 0.037), FLT3-ITD and RUNX1 mutations independently contributed to poor OS (P = 0.035, P = 0.014, respectively). In conclusion, older age was an important risk factor for IR-AML patients undergoing chemotherapy-only; FLT3-ITD, MLL-PTD and RUNX1 mutations were significant risk factors for IR-AML patients who received allo-HSCT.

Molecular Malfeasance Mediating Myeloid Malignancies: The Genetics of Acute Myeloid Leukemia

A remarkable number of different, but recurrent, structural cytogenetic abnormalities have been observed in AML, and the 2016 WHO AML classification system incorporates numerous distinct entities associated with translocations or inversions, as well as others associated with single gene mutations into a category entitled "AML with recurrent genetic abnormalities." The AML classification is heavily reliant on cytogenetic and molecular information based on conventional genetic techniques (including karyotype, fluorescence in situ hybridization, reverse transcriptase polymerase chain reaction, single gene sequencing), but large-scale next generation sequencing is now identifying novel mutations. With targeted next generation sequencing panels now clinically available at many centers, detection of mutations, as well as alterations in epigenetic modifiers, is becoming part of the routine diagnostic evaluation of AML and will likely impact future classification schemes.

Distinct genetic alteration profiles of acute myeloid leukemia between Caucasian and Eastern Asian population

Racial and ethnic disparities in malignancies attract extensive attention. To investigate whether there are racial and ethnic disparities in genetic alteration between Caucasian and Eastern Asian population, data from several prospective AML trials were retrospectively analyzed in this study. We found that there were more patients with core binding factor (CBF) leukemia in Eastern Asian cohorts and there were different CBF leukemia constitutions between them. The ratios of CBF leukemia are 27.7, 22.1, 21.1, and 23.4%, respectively, in our (ChiCTR-TRC-10001202), another Chinese, Korean, and Japanese Eastern Asian cohorts, which are significantly higher than those in ECOG1900, MRC AML15, UK NCRI AML17, HOVON/SAKK AML-42, and German AML2003 (15.5, 12.5, 9.3, 10.2, and 12%, respectively). And CBFbeta-MYH11 occurred more prevalently in HOVON/SAKK AML- 42 and ECOG1900 trials (50.0 and 54.3% of CBF leukemia, respectively) than in Chinese and Japanese trials (20.1 and 20.8%, respectively). The proportion of FLT3-ITD mutation is 11.2% in our cohort, which is lower than that in MRC AML15 and UK NCRI AML17 (24.6 and 17.9%, respectively). Even after excluding the age bias, there are still different incidence rates of mutation between Caucasian and Eastern Asian population. These data suggest that there are racial and ethnic disparities in genetic alteration between Caucasian and Eastern Asian population.

Genotypic and clinical heterogeneity within NCCN favorable-risk acute myeloid leukemia

The National Comprehensive Cancer Network (NCCN) defines the following types of acute myeloid leukemia (AML) as favorable-risk: acute promyelocytic leukemia with t(15;17) (APL); AML with core-binding factor (CBF) rearrangements, including t(8;21) and inv(16) or t(16;16) without mutations in KIT (CBF-KIT^wt); and AML with normal cytogenetics and mutations in NPM1 (NPM1^mut); or biallelic mutations in CEBPA (CEBPA^mut/mut), without FLT3-ITD. Although these AMLs are categorized as favorable risk by NCCN, clinical experience suggests that there are differences in clinical outcome amongst these cytogenetically and molecularly distinct leukemias. This study compared clinical and genotypic characteristics of 60 patients with favorable-risk AML, excluding APL, and demonstrated significant differences between them. Patients with NPM1^mut AML were significantly older than those in the other groups. Targeted next-generation sequencing on DNA from peripheral blood or bone marrow revealed significantly more mutations in NPM1^mut AML than the other favorable-risk diseases, especially in genes related to DNA splicing and methylation. CEBPA^mut/mut AMLs exhibited more mutations in transcription-related genes. Patients with NPM1^mut AML and CEBPA^mut/mut AML show significantly reduced overall survival in comparison with CBF-KIT^wt AML. These findings emphasize that favorable-risk AML patients have divergent outcomes and that differences in clinical and genotypic characteristics should be considered in their evaluation and management.

Variable outcome and methylation status according to CEBPA mutant type in double-mutated acute myeloid leukemia patients and the possible implications for treatment

Although CEBPA double-mutated (CEBPADM) acute myeloid leukemia is considered to be a favorable-risk disease, relapse remains a major cause of treatment failure. Most CEBPADM patients have a classic biallelic mutant combination with an N-terminal mutation leading to production of p30 protein plus a C-terminal loss-of-function in-frame indel mutation (CEBPAClassic-DM), but approximately one-third of cases have one or more non-classic mutations, with diverse combinations reported, and there is little information on the consequences of such mutants. We evaluated outcome in a cohort of 104 CEBPADM patients, 79 CEBPAClassic-DM and 25 with non-classic mutants, and found that the latter may have poorer survival (5-year overall survival 64% vs. 46%; P=0.05), particularly post relapse (41% vs. 0%; P=0.02). However, for this analysis, all non-classic cases were grouped together, irrespective of mutant combination. As CEBPADM cases have been reported to be hypermethylated, we used methylation profiling to assess whether this could segregate the different mutants. We developed a CEBPAClassic-DM methylation signature from a preliminary cohort of 10 CEBPADM (including 8 CEBPAClassic-DM) and 30 CEBPA wild-type (CEBPAWT) samples, and independently validated the signature in 17 CEBPAClassic-DM cases. Assessment of the signature in 16 CEBPADM cases with different non-classic mutant combinations showed that only 31% had a methylation profile equivalent to CEBPAClassic-DM whereas for 69% the profile was either intermediate between CEBPAClassic-DM and CEBPAWT or equivalent to CEBPAWT These results suggest that CEBPADM cases with non-classic mutants may be functionally different from those with CEBPAClassic-DM mutants, and should not automatically be included in the same prognostic group. (AML12 is registered under ISRCTN17833622 and AML15 under ISRCTN17161961).

Disruption of the C/EBPα-miR-182 balance impairs granulocytic differentiation

Transcription factor C/EBPα is a master regulator of myelopoiesis and its inactivation is associated with acute myeloid leukemia. Deregulation of C/EBPα by microRNAs during granulopoiesis or acute myeloid leukemia development has not been studied. Here we show that oncogenic miR-182 is a strong regulator of C/EBPα. Moreover, we identify a regulatory loop between C/EBPα and miR-182. While C/EBPα blocks miR-182 expression by direct promoter binding during myeloid differentiation, enforced expression of miR-182 reduces C/EBPα protein level and impairs granulopoiesis in vitro and in vivo. In addition, miR-182 expression is highly elevated particularly in acute myeloid leukemia patients with C-terminal CEBPA mutations, thereby depicting a mechanism by which C/EBPα blocks miR-182 expression. Furthermore, we present miR-182 expression as a prognostic marker in cytogenetically high-risk acute myeloid leukemia patients. Our data demonstrate the importance of a controlled balance between C/EBPα and miR-182 for the maintenance of healthy granulopoiesis.

C/EBPα is a critical transcription factor involved in myelopoiesis and its inactivation is associated with acute myeloid leukemia (AML). Here the authors show a negative feedback loop between C/EBPα and miR-182 and identify this miRNA as a marker of high-risk AML.

NEDD9, an independent good prognostic factor in intermediate-risk acute myeloid leukemia patients

Intermediate-risk acute myeloid leukemia (IR-AML) is the largest subgroup of AML patients and is highly heterogeneous. Whereas adverse and favourable risk patients have well-established treatment protocols, IR-AML patients have not. It is, therefore, crucial to find novel factors that stratify this subgroup to implement risk-adapted strategies. The CAS (Crk-associated substrate) adaptor protein family regulates cell proliferation, survival, migration and adhesion. Despite its association with metastatic dissemination and prognosis of different solid tumors, the role of these proteins in hematological malignancies has been scarcely evaluated. Nevertheless, previous work has established an important role for the CAS family members NEDD9 or BCAR1 in the migratory and dissemination capacities of myeloid cells. On this basis, we hypothesized that NEDD9 or BCAR1 expression levels could associate with survival in IR-AML patients and become new prognostic markers. To that purpose, we assessed BCAR1 and NEDD9 gene expression in a cohort of 73 adult AML patients validating the results in an independent cohort (n = 206). We have identified NEDD9, but not BCAR1, as a new a marker for longer overall and disease-free survival, and for lower cumulative incidence of relapse. In summary, NEDD9 gene expression is an independent prognostic factor for favourable prognosis in IR-AML patients.

Diagnosis and classification of hematologic malignancies on the basis of genetics

Genomic analysis has greatly influenced the diagnosis and clinical management of patients affected by diverse forms of hematologic malignancies. Here, we review how genetic alterations define subclasses of patients with acute leukemias, myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPNs), non-Hodgkin lymphomas, and classical Hodgkin lymphoma. These include new subtypes of acute myeloid leukemia defined by mutations in RUNX1 or BCR-ABL1 translocations as well as a constellation of somatic structural DNA alterations in acute lymphoblastic leukemia. Among patients with MDS, detection of mutations in SF3B1 define a subgroup of patients with the ring sideroblast form of MDS and a favorable prognosis. For patients with MPNs, detection of the BCR-ABL1 fusion delineates chronic myeloid leukemia from classic BCR-ABL1^- MPNs, which are largely defined by mutations in JAK2, CALR, or MPL In the B-cell lymphomas, detection of characteristic rearrangements involving MYC in Burkitt lymphoma, BCL2 in follicular lymphoma, and MYC/BCL2/BCL6 in high-grade B-cell lymphomas are essential for diagnosis. In T-cell lymphomas, anaplastic large-cell lymphoma is defined by mutually exclusive rearrangements of ALK, DUSP22/IRF4, and TP63 Genetic alterations affecting TP53 and the mutational status of the immunoglobulin heavy-chain variable region are important in clinical management of chronic lymphocytic leukemia. Additionally, detection of BRAFV600E mutations is helpful in the diagnosis of classical hairy cell leukemia and a number of histiocytic neoplasms. Numerous additional examples provided here demonstrate how clinical evaluation of genomic alterations have refined classification of myeloid neoplasms and major forms of lymphomas arising from B, T, or natural killer cells.

Retinoic acid and arsenic trioxide in the treatment of acute promyelocytic leukemia: current perspectives

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML) with a unique morphological appearance, associated coagulopathy and canonical balanced translocation of genetic material between chromosomes 15 and 17. APL was first described as a distinct subtype of AML in 1957 by Dr Leif Hillestad who recognized the pattern of an acute leukemia associated with fibrinolysis, hypofibrinogenemia and catastrophic hemorrhage. In the intervening years, the characteristic morphology of APL has been described fully with both classical hypergranular and variant microgranular forms. Both are characterized by a balanced translocation between the long arms of chromosomes 15 and 17, [t(15;17)(q24;q21)], giving rise to a unique fusion gene PML-RARA and an abnormal chimeric transcription factor (PML-RARA), which disrupts normal myeloid differentiation programs. The success of current treatments for APL is in marked contrast to the vast majority of patients with non-promyelocytic AML. The overall prognosis in non-promyelocytic AML is poor, and although there has been an improvement in overall survival in patients aged <60 years, only 30%-40% of younger patients are still alive 5 years after diagnosis. APL therapy has diverged from standard AML therapy through the empirical discovery of two agents that directly target the molecular basis of the disease. The evolution of treatment over the last 4 decades to include all-trans retinoic acid and arsenic trioxide, with chemotherapy limited to patients with high-risk disease, has led to complete remission in 90%-100% of patients in trials and rates of overall survival between 86% and 97%.

Biological and clinical consequences of NPM1 mutations in AML

Acute myeloid leukemia (AML) is characterized by accumulation of myeloid cells in the bone marrow because of impaired differentiation and proliferation, resulting in hematopoietic insufficiency. NPM1 is one of the most commonly mutated genes in AML, present in 20-30% of cases. Mutations in NPM1 represent a distinct entity in the World Health Organization (WHO) classification and commonly indicate a better risk prognosis. In this review, we discuss the many functions of NPM1, the consequence of mutations in NPM1 and possible mechanisms through which mutations lead to leukemogenesis. We also discuss clinical consequences of mutations, associated gene expression patterns and the role of NPM1 mutations in informing prognosis and therapeutic decisions and predicting relapse in AML.

Genetic Testing in Acute Myeloid Leukemia and Myelodysplastic Syndromes

Cytogenetic analysis of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) is essential for disease diagnosis, classification, prognostic stratification, and treatment guidance. Molecular genetic analysis of CEBPA, NPM1, and FLT3 is already standard of care in patients with AML, and mutations in several additional genes are assuming increasing importance. Mutational analysis of certain genes, such as SF3B1, is also becoming an important tool to distinguish subsets of MDS that have different biologic behaviors. It is still uncertain how to optimally combine karyotype with mutation data in diagnosis and risk-stratification of AML and MDS, particularly in cases with multiple mutations and/or several mutationally distinct subclones.

Diagnosis and management of AML in adults: 2017 ELN recommendations from an international expert panel

The first edition of the European LeukemiaNet (ELN) recommendations for diagnosis and management of acute myeloid leukemia (AML) in adults, published in 2010, has found broad acceptance by physicians and investigators caring for patients with AML. Recent advances, for example, in the discovery of the genomic landscape of the disease, in the development of assays for genetic testing and for detecting minimal residual disease (MRD), as well as in the development of novel antileukemic agents, prompted an international panel to provide updated evidence- and expert opinion-based recommendations. The recommendations include a revised version of the ELN genetic categories, a proposal for a response category based on MRD status, and criteria for progressive disease.

CEBPA-double-mutated acute myeloid leukemia displays a unique phenotypic profile: a reliable screening method and insight into biological features

Mutations in CCAAT/enhancer binding protein α (CEBPA) occur in 5-10% of cases of acute myeloid leukemia. CEBPA-double-mutated cases usually bear biallelic N- and C-terminal mutations and are associated with a favorable clinical outcome. Identification of CEBPA mutants is challenging because of the variety of mutations, intrinsic characteristics of the gene and technical issues. Several screening methods (fragment-length analysis, gene expression array) have been proposed especially for large-scale clinical use; although efficient, they are limited by specific concerns. We investigated the phenotypic profile of blast and maturing bone marrow cell compartments at diagnosis in 251 cases of acute myeloid leukemia. In this cohort, 16 (6.4%) patients had two CEBPA mutations, whereas ten (4.0%) had a single mutation. First, we highlighted that the CEBPA-double-mutated subset displays recurrent phenotypic abnormalities in all cell compartments. By mutational analysis after cell sorting, we demonstrated that this common phenotypic signature depends on CEBPA-double-mutated multi-lineage involvement. From a multidimensional study of phenotypic data, we developed a classifier including ten core and widely available parameters. The selected markers on blasts (CD34, CD117, CD7, CD15, CD65), neutrophil (SSC, CD64), monocytic (CD14, CD64) and erythroid (CD117) compartments were able to cluster CEBPA-double-mutated cases. In a validation set of 259 AML cases from three independent centers, our classifier showed excellent performance with 100% specificity and 100% sensitivity. We have, therefore, established a reliable screening method, based upon multidimensional analysis of widely available phenotypic parameters. This method provides early results and is suitable for large-scale detection of CEBPA-double-mutated status, allowing gene sequencing to be focused in selected cases.

Selecting initial treatment of acute myeloid leukaemia in older adults

More than half of the patients with acute myeloid leukaemia (AML) are older than 60years. The treatment outcomes in this group remain poor with a median overall survival of <1year. Selecting initial treatment for these patients involves an assessment of 'fitness' for induction chemotherapy. This is done based on patient and disease-related characteristics which help to estimate treatment-related mortality and chance of complete remission with induction chemotherapy. If the risk of treatment-related mortality is high and/or the likelihood of a patient achieving a complete remission is low, lower-intensity treatment (low-dose cytarabine, decitabine and azacitidine) should be discussed. As outcomes in both groups of patients remain poor, enrolment into clinical trials of novel agents with varying mechanisms of action should be considered for all older adults with AML. Novel agents in Phase III development include CPX-351, guadecitabine (SGI-110), quizartinib, crenolanib, sapacitabine, vosaroxin and volasertib.

Molecular biomarkers in acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. The pathophysiology of this disease is just beginning to be understood at the cellular and molecular level, and currently cytogenetic markers are the most important for risk stratification and treatment of AML patients. However, with the advent of new technologies, the detection of other molecular markers such as point mutations and characterization of epigenetic and proteomic profiles, have begun to play an important role in how the disease is approached. Recent evidence shows that the identification of new AML biomarkers contributes to a better understanding of the molecular basis of the disease, is significantly useful in screening, diagnosis, prognosis and monitoring of AML, as well as the possibility of predicting each individual's response to treatment. This review summarizes the most relevant molecular (genetic, epigenetic, and protein) biomarkers associated with acute myeloid leukemia and discusses their clinical importance in terms of risk prediction, diagnosis and prognosis.

Genetically distinct leukemic stem cells in human CD34- acute myeloid leukemia are arrested at a hemopoietic precursor-like stage

Quek and colleagues identify human leukemic stem cells (LSCs) present in CD34⁻ AML. In-depth characterization of the functional and clonal aspects of CD34⁻ LSCs indicates that most are similar to myeloid precursors.

Our understanding of the perturbation of normal cellular differentiation hierarchies to create tumor-propagating stem cell populations is incomplete. In human acute myeloid leukemia (AML), current models suggest transformation creates leukemic stem cell (LSC) populations arrested at a progenitor-like stage expressing cell surface CD34. We show that in ∼25% of AML, with a distinct genetic mutation pattern where >98% of cells are CD34⁻, there are multiple, nonhierarchically arranged CD34⁺ and CD34⁻ LSC populations. Within CD34⁻ and CD34⁺ LSC–containing populations, LSC frequencies are similar; there are shared clonal structures and near-identical transcriptional signatures. CD34⁻ LSCs have disordered global transcription profiles, but these profiles are enriched for transcriptional signatures of normal CD34⁻ mature granulocyte–macrophage precursors, downstream of progenitors. But unlike mature precursors, LSCs express multiple normal stem cell transcriptional regulators previously implicated in LSC function. This suggests a new refined model of the relationship between LSCs and normal hemopoiesis in which the nature of genetic/epigenetic changes determines the disordered transcriptional program, resulting in LSC differentiation arrest at stages that are most like either progenitor or precursor stages of hemopoiesis.

CEBPA mutations in patients with de novo acute myeloid leukemia: data analysis in a Chinese population

Background

This study was aimed to explore the clinical characteristics and prognoses of acute myeloid leukemia (AML) patients with CEBPA mutations.

Patients and methods

Three hundred and forty-five patients with de novo AML were retrospectively analyzed with regard to CEBPA mutations, clinical characteristics, therapeutic responses, and long-term outcomes.

Results

CEBPA mutations were detected in 59 patients (17.10%), with 47 cases harboring double mutations and 12 cases harboring single mutations. In those with a normal karyotype (NK), 44 cases (25.29%) were detected with CEBPA mutations. The following characteristics were observed in CEBPA-mutated patients: most (66.10%) of them were M₁ or M₂; they presented with higher peripheral white blood cell counts (23.71 [12.6, 60.02] ×10⁹/L versus 7.34 [2.38, 26.63] ×10⁹/L; u=4.944, P<0.001) and higher hemoglobin levels (89.64±23.05 g/L versus 75.65±23.65 g/L; t=4.156, P<0.001) than those observed in patients without the mutation; and the expression of CD7 and HLA-DR was higher, whereas that of CD34 and CD56 was lower in patients with the mutation than in those without the mutation. Compared with those without the mutation, patients with CEBPA mutations had a superior complete remission rate (75.0% versus 56.54%; χ²=6.185, P=0.013) and superior overall survival (P=0.034).

Conclusion

The frequency of CEBPA mutations may be higher in Chinese patients with AML than has been reported in populations of western countries, and the presence of CEBPA mutations is an indication of favorable prognoses for these patients.

Acute myeloid leukemia in the era of precision medicine: recent advances in diagnostic classification and risk stratification

Acute myeloid leukemia (AML) is a genetically heterogeneous myeloid malignancy that occurs more commonly in adults, and has an increasing incidence, most likely due to increasing age. Precise diagnostic classification of AML requires clinical and pathologic information, the latter including morphologic, immunophenotypic, cytogenetic and molecular genetic analysis. Risk stratification in AML requires cytogenetics evaluation as the most important predictor, with genetic mutations providing additional necessary information. AML with normal cytogenetics comprises about 40%-50% of all AML, and has been intensively investigated. The currently used 2008 World Health Organization classification of hematopoietic neoplasms has been proposed to be updated in 2016, also to include an update on the classification of AML, due to the continuously increasing application of genomic techniques that have led to major advances in our knowledge of the pathogenesis of AML. The purpose of this review is to describe some of these recent major advances in the diagnostic classification and risk stratification of AML.