IDH mutations and trisomy 8 in myelodysplastic syndromes and acute myeloid leukemia

IDH2 mutations in acute myeloid leukemia

Advances in the treatment of acute myeloid leukemia (AML) over the last 40 years have been limited. With an improved understanding of the pathophysiology of the disease, the advent of new treatment options has enriched the armamentarium of the physician to combat the disease. Mutations of the isocitrate dehydrogenase (IDHs) genes are common in AML and occur in 20-30% of cases. These mutations lead to DNA hypermethylation, aberrant gene expression, cell proliferation, and abnormal differentiation. Targeting mutant IDH, either as monotherapy or in combination with hypomethylating agents (HMAs) or BCL-2 inhibitors, has opened new avenues of therapy for these patients.This review will outline the function of IDHs and focus on the biological effects of IDH2 mutations in AML, their prognosis and treatment options.

Molecular genetic and clinical characterization of acute myeloid leukemia with trisomy 8 as the sole chromosome abnormality

INTRODUCTION

The aim of the study was to determine molecular genetic and clinical characterization of acute myeloid leukemia (AML) with trisomy 8 as the sole chromosome abnormality, a recurrent but rare chromosomal abnormality in AML.

METHODS

Interphase fluorescence in situ hybridization, reverse transcriptase-quantitative polymerase chain reaction for gene rearrangement and next-generation sequencing (NGS) were performed on sole trisomy 8 AML patients.

RESULTS

A total of 35 AML patients with trisomy 8 as the sole chromosome abnormality were screened. The most frequently mutated genes were DNMT3A(37.1%), RUNX1(28.6%), FLT3-ITD(28.6%), IDH2(22.9%), NPM1(17.1%), and ASXL1 (14.3%). The sole +8 AML patients exhibited more mutations in RUNX1 (28.6% vs. 4.8%, P = 0.001) and ASXL1 (14.3% vs. 4.8%, P = 0.039) by comparing with normal karyotype AML (NK AML) patients(n = 63). The sole +8 AML patients(n = 35) with RUNX1 or IDH2 mutations showed significantly lower WBC counts, while FLT3-ITD showed higher white blood cell (WBC) counts as compared to the corresponding wild-type groups. Total of 45.7% patients achieved complete remission (CR) after the first induction therapy. The CR rate of patients with FLT3-ITD or IDH1 mutation was significantly lower than that in the corresponding wild-type cases (P = 0.047, 0.005, respectively). The median overall survival (OS) and disease-free survival (PFS) were 18.0 (95% CI: 10.8-25.2) and 10 (95% CI: 6.7-13.3) months, respectively. FLT3-ITD mutations and allogeneic hematopoietic stem cell transplantation (allo-HSCT) were independent prognostic markers for OS in multivariable analysis.

CONCLUSION

The results suggest a possible association between trisomy 8 and additional mutations that may influence clinical feature and prognosis.

Clinical significance of cytogenetic and molecular genetic abnormalities in 634 Chinese patients with myelodysplastic syndromes

Purpose

To explore the relevance of cytogenetic or molecular genetic abnormalities to clinical variables, including clinical and laboratory characteristics and prognosis in Chinese patients with myelodysplastic syndromes (MDS).

Methods

A total of 634 consecutive patients diagnosed with MDS at The First Affiliated Hospital, Zhejiang University School of Medicine from June 2008 to May 2018 were retrospectively included in this study. All patients had evaluable cytogenetic analysis, and 425 patients had MDS‐related mutations sequencing.

Results

38.6% of patients displayed abnormal karyotypes. The most common cytogenetic abnormality was +8 (31%). Sole +8 was related to female (p = 0.002), hemoglobin >10 g/dL (p = 0.03), and <60 years old (p = 0.046). TP53 mutations were associated with complex karyotype (CK) (p < 0.001). DNMT3A mutations correlated with ‐Y (p = 0.01) whereas NRAS mutations correlated with 20q‐ (p = 0.04). The overall survival (OS) was significantly inferior in patients with +8 compared with those with normal karyotype (NK) (p = 0.003). However, the OS of sole +8 and +8 with one additional karyotypic abnormality was not different from NK (p = 0.16), but +8 with two or more abnormalities had a significantly shorter OS than +8 and +8 with one additional karyotypic abnormality (p = 0.02). In multivariable analysis, ≥60 years old, marrow blasts ≥5% and TP53 mutations were independent predictors for poor OS (p < 0.05), whereas SF3B1 mutations indicated better prognosis. Male IDH1 and IDH2 mutations and marrow blasts ≥5% were independent risk factors for worse leukemia free survival (LFS) (p < 0.05).

Conclusion

In this population of Chinese patients, trisomy 8 is the most common karyotypic abnormality. Patients with +8 showed a poorer OS compared with patients with NK. Sole +8 and +8 with one additional karyotypic abnormality had similar OS with NK, whereas +8 with two or more abnormalities had a significantly shorter OS. DNMT3A mutations correlated with ‐Y and NRAS mutations correlated with 20q‐. TP53 mutations were associated with CK and had a poor OS. SF3B1 mutations indicated a favorable OS. IDH1 and IDH2 mutations independently indicated inferior LFS.

Trisomy 8 in acute myeloid leukemia

Introduction: Trisomy 8 is one of the most common cytogenetic alterations in acute myeloid leukemia (AML), with a frequency between 10% and 15%.Areas covered: The authors summarize the latest research regarding biological, translational and clinical aspects of trisomy 8 in AML.Expert opinion: Trisomy 8 can be found together with other karyotypes, although it also occurs as a sole aberration. The last decade's research has brought attention to molecular genetic alterations as strong contributors of leukemogenesis. AML with trisomy 8 seems to be associated with mutations in DNA methylation genes, spliceosome complex genes, and myeloid transcription factor genes, and these alterations probably have stronger implication for leukemic pathogenesis, treatment and hence prognosis, than the existence of trisomy 8 itself. Especially mutations in the RUNX1 and ASXL1 genes occur in high frequencies, and search for such mutations should be mandatory part of the diagnostic workup. AML with trisomy 8 is classified as intermediate-risk AML after recent European Leukemia Net (ELN) classification, and hence allogenic hematopoietic stem cell transplantation (Allo-HSCT) should be consider as consolidation therapy for this patient group.Trisomy 8 is frequently occurring in AML, although future molecular genetic workup should be performed, to optimize the diagnosis and treatment of these patients.

Monozygotic twins with shared de novo GATA2 mutation but dissimilar phenotypes due to differential promoter methylation

A revised WHO classification of hematopoietic neoplasm introduced the new category 'Myeloid Neoplasms with Germline Predisposition', reflecting the growing importance of genetic testing for myeloid neoplasms. Here, we investigated monozygotic twins with the same de novo mutation in GATA2 but different phenotypes. The patient suffering a bleeding tendency was diagnosed with myelodysplastic syndrome (MDS), and her monozygotic twin showed dysmegakaryopoietic features in the bone marrow. Targeted sequencing revealed the same germline mutation in GATA2, c.1192C > T, in both sisters and different somatic mutations in 14 genes between the sisters. The GATA2 mutation was absent in both parents, and their hemograms were normal. The methylation profile of the GATA2 promoter region was different between the twins, showing denser promoter methylation in the patient, correlated with MDS. Thus, we concluded that the twins had acquired a de novo GATA2 mutation but showed different phenotypes, possibly due to the critical role of epigenetic changes.

Assessing copy number aberrations and copy neutral loss of heterozygosity across the genome as best practice: An evidence based review of clinical utility from the cancer genomics consortium (CGC) working group for myelodysplastic syndrome, myelodysplastic/myeloproliferative and myeloproliferative neoplasms

Multiple studies have demonstrated the utility of chromosomal microarray (CMA) testing to identify clinically significant copy number alterations (CNAs) and copy-neutral loss-of-heterozygosity (CN-LOH) in myeloid malignancies. However, guidelines for integrating CMA as a standard practice for diagnostic evaluation, assessment of prognosis and predicting treatment response are still lacking. CMA has not been recommended for clinical work-up of myeloid malignancies by the WHO 2016 or the NCCN 2017 guidelines but is a suggested test by the European LeukaemiaNet 2013 for the diagnosis of primary myelodysplastic syndrome (MDS). The Cancer Genomics Consortium (CGC) Working Group for Myeloid Neoplasms systematically reviewed peer-reviewed literature to determine the power of CMA in (1) improving diagnostic yield, (2) refining risk stratification, and (3) providing additional genomic information to guide therapy. In this manuscript, we summarize the evidence base for the clinical utility of array testing in the workup of MDS, myelodysplastic/myeloproliferative neoplasms (MDS/MPN) and myeloproliferative neoplasms (MPN). This review provides a list of recurrent CNAs and CN-LOH noted in this disease spectrum and describes the clinical significance of the aberrations and how they complement gene mutation findings by sequencing. Furthermore, for new or suspected diagnosis of MDS or MPN, we present suggestions for integrating genomic testing methods (CMA and mutation testing by next generation sequencing) into the current standard-of-care clinical laboratory testing (karyotype, FISH, morphology, and flow).

The role of mutant IDH1 and IDH2 inhibitors in the treatment of acute myeloid leukemia

For decades, researchers have looked into the pathophysiology of acute myeloid leukemia (AML). With the advances in molecular techniques, the two-hit hypothesis was replaced by a multi-hit model, which also emphasizes the importance of aberrant epigenetic regulation in the pathogenesis of AML. IDH1 and IDH2 are two isoforms of isocitrate dehydrogenase that perform crucial roles in cellular metabolism. Somatic mutations in either of these two genes impart a neomorphic enzymatic activity upon the encoded enzymes resulting in the ability to convert α-ketoglutarate (αKG) into the oncometabolite R2-hydroxyglutarate (R2-HG), which can competitively inhibit multiple αKG-dependent dioxygenases. Inhibition of various classes of αKG-dependent dioxygenases results in dramatic epigenetic changes in hematopoietic cells, which has been found to directly impair differentiation. In addition to a global dysregulation of gene expression, other mechanisms have been described through which R2-HG promotes leukemic transformation including the induction of B cell lymphoma 2 dependency and stimulation of the EglN family of prolyl 4-hydroxylases (EglN). Due to the fact that mutations in IDH1 and IDH2 are acquired early during AML clonal evolution as well as because these mutations tend to remain stable during AML progression, the pharmaceutical industry has prompted the development of specific mutant IDH enzyme inhibitors. More recently, the FDA approved the first mutant IDH2 inhibitor, enasidenib (AG-221), for patients with relapsed or refractory IDH2-mutated AML (RR-AML). This has brought a lot of excitement to researchers, clinicians, and patients, especially because the treatment of AML remains challenging and is still associated with a high mortality.

IDH1 Mutation Is an Independent Inferior Prognostic Indicator for Patients with Myelodysplastic Syndromes

BACKGROUND

Genomic sequencing technologies have identified isocitrate dehydrogenase (IDH) mutations in haematological malignancies. The prognostic implications of somatic IDH mutation (mIDH) in myelodysplastic syndromes (MDS) remain controversial.

METHODS

Mutations in IDH1 and IDH2 were detected using genomic sequencing technologies in 97 patients with MDS.

RESULTS

Seven (7.2%) mutations were identified: 3 in IDH1 (all R132C) and 4 in IDH2 (3 R140Q and 1 R140L). The frequency of mutation was 16.6% (2/12) in refractory anaemia with excess blasts (RAEB)-1 and 14.7% (5/34) in RAEB-2. IDH1/2 mutations were closely associated with higher bone marrow blast counts (median 10.0 vs. 2.3%; p = 0.019) and lower absolute neutrophil counts (median 0.44 × 109/L vs. 1.21 × 109/L; p = 0.027). All IDH mutations were mutually exclusive and heterozygous. IDH mutations were not significantly correlated with any specific karyotype. Patients with IDH1 mutations exhibited shorter overall and progression-free survival (OS and PFS; p = 0.039 and p = 0.042, respectively), whereas IDH2 mutations did not affect OS or PFS (p = 0.560 and p = 0.218, respectively). Multivariate analysis indicated that IDH1 mutation (p = 0.018; hazard ratio [HR] 4.735; 95% confidence interval [CI] 1.299-17.264), karyotype risk (p = 0.036; HR 1.619; 95% CI 1.033-2.539) and the revised International Prognostic Scoring System risk category (p < 0.0001; HR 2.122; 95% CI 1.401-3.213) were independent inferior prognostic factors.

CONCLUSIONS

IDH1 mutation is associated with a poor prognosis.

Techniques for detecting chromosomal aberrations in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of heterogeneous hematologic diseases. Chromosomal aberrations are important for the initiation, development, and progression of MDS. Detection of chromosomal abnormalities in MDS is important for categorization, risk stratification, therapeutic selection, and prognosis evaluation of the disease. Recent progress of multiple techniques has brought powerful molecular cytogenetic information to reveal copy number variation, uniparental disomy, and complex chromosomal aberrations in MDS. In this review, we will introduce some common chromosomal aberrations in MDS and their clinical significance. Then we will explain the application, advantages, and limitations of different techniques for detecting chromosomal abnormalities in MDS. The information in this review may be helpful for clinicians to select appropriate methods in patient-related decision making.

A Zebrafish Model for Evaluating the Function of Human Leukemic Gene IDH1 and Its Mutation

The recent advent of next-generation sequencing (NGS) has greatly accelerated identification of gene mutations in myeloid malignancies at unprecedented speed that will soon outpace their functional validation by conventional laboratory techniques and animal models. A high-throughput whole-organism model is useful for the functional validation of new mutations. We recently reported the use of zebrafish to evaluate the hematopoietic function of isocitrate dehydrogenase 1 (IDH1) and the effects of expressing human IDH1-R132H that is frequently identified in human acute myeloid leukemia (AML), in myelopoiesis, with a view to develop zebrafish as a model of AML. Here, we use IDH1 as an example to describe a comprehensive approach to evaluate hematopoietic gene function and the effects of mutations using zebrafish as a model.

Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Adult Patients with Myelodysplastic Syndrome Harboring Trisomy 8

Trisomy 8 (+8) is 1 of the most common cytogenetic abnormalities in adult patients with myelodysplastic syndrome (MDS). However, the outcome of allogeneic hematopoietic stem cell transplantation (HSCT) in adult patients with MDS harboring +8 remains unclear. To evaluate the outcome and prognostic factors in patients with MDS harboring +8 as the sole cytogenetic abnormality or in association with other abnormalities, we retrospectively analyzed the Japanese registration data of 381 adult patients with MDS harboring +8 treated with allogeneic HSCT between 1990 and 2013. With a median follow-up period of 53 months, the probability of overall survival and cumulative incidence of relapse at 4 years were 51% and 22%, respectively. In the multivariate analysis, age > 50 years, 2 or more additional cytogenetic abnormalities, and a high risk at the time of HSCT according to the FAB/WHO classification were significantly associated with a higher overall mortality. Nevertheless, no significant impact of the outcome was observed in patients with 1 cytogenetic abnormality in addition to +8. Although 221 patients (58%) had advanced MDS at the time of HSCT, allogeneic HSCT offered a curative option for adult patients with MDS harboring +8.

Metabolic interactions with cancer epigenetics

Cancer cells have epigenetic alterations that are known to drive cancer progression. The reversibility of the epigenetic posttranslational modifications on chromatin and DNA renders targeting these modifications an attractive means for cancer therapy. Cellular epigenetic status interacts with cell metabolism, and we are now beginning to understand the nature of how this interaction occurs and the biological contexts that mediate its function. Given the tremendous interest in understanding and targeting metabolic reprogramming in cancer, this nexus also provides opportunities for exploring the liabilities of cancers. This review summarizes recent developments in our understanding of the interaction of cancer metabolism and epigenetics.

5-hydroxymethylcytosine in cancer: significance in diagnosis and therapy

Emerging data have demonstrated that 5-methylcytosine (5-mC) and its oxidized products 5-hydroxymethylcytosine (5-hmC), 5-formylcytosine (5-fC), and 5-carboxylcytosine (5-CaC) play unique roles in several biological processes, including the control of gene expression and in the pathogenesis of cancer. In this review, we focus on 5-hmC and the disruption of its distribution in several cancers, including hematological malignancies and solid tumors. We present an outline of how 5-hmC is closely associated with metabolic pathways and may be the missing link connecting epigenetics with metabolism in the context of cancer cells. Finally, we discuss the diagnostic and prognostic importance of 5-mC and 5-hmC patterning, and how we may be able to establish new paradigms in cancer therapy based on these alterations.

Prognostic value of isocitrate dehydrogenase mutations in myelodysplastic syndromes: a retrospective cohort study and meta-analysis

Background

Recent genomic sequencing efforts have identified a number of recurrent mutations in myelodysplastic syndromes (MDS) that may contribute to disease progression and overall survival, including mutations in isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2).

Methods

Pretreatment bone marrow (BM) samples were acquired from mononuclear cells in 146 adult patients with de novo MDS from January 2006 to June 2013. Polymerase chain reaction (PCR) and direct sequencing were performed on exon 4 of IDH1/2 genes and mutation status was correlated with overall survival (OS) and leukemia-free survival (LFS). We then performed a meta-analysis combining previously published and current studies to explore the effect of IDH mutations on OS and LFS in MDS.

Results

In our study, somatic mutations of either IDH gene were discovered in 11 MDS patients (7.53%) and were significantly correlated with poorer OS (P = 0.007). IDH mutations were specifically associated with a poorer OS in the intermediate-1 risk group by the International Prognostic Scoring System (IPSS) (P = 0.039). In addition, we discovered decitabine achieved a better therapeutic effect compared to other treatments in IDH mutation-positive patients (P = 0.023). We identified six previous studies of IDH mutations in MDS. A meta-analysis of these studies included 111 MDS patients IDH mutations and 1671 MDS patients with wild-type IDH1/2. The hazard ratios (HRs) of OS and LFS for patients with IDH mutations were 1.62 (95% CI, 1.27–2.09) and 2.21 (95% CI, 1.48–3.30), respectively.

Conclusion

The results from our study and the meta-analysis provide firm evidence that IDH mutations are significantly associated with poorer clinical outcomes in MDS. Identification of IDH mutations may be pivotal for better risk stratification in MDS patients and improving IPSS score. Additionally, hypomethylating agents may be an effective treatment option for MDS patients with IDH mutations.

DNMT3A and IDH mutations in acute myeloid leukemia and other myeloid malignancies: associations with prognosis and potential treatment strategies

The development of effective treatment strategies for most forms of acute myeloid leukemia (AML) has languished for the past several decades. There are a number of reasons for this, but key among them is the considerable heterogeneity of this disease and the paucity of molecular markers that can be used to predict clinical outcomes and responsiveness to different therapies. The recent large-scale sequencing of AML genomes is now providing opportunities for patient stratification and personalized approaches to treatment that are based on individual mutational profiles. It is particularly notable that studies by The Cancer Genome Atlas and others have determined that 44% of patients with AML exhibit mutations in genes that regulate methylation of genomic DNA. In particular, frequent mutation has been observed in the genes encoding DNA methyltransferase 3A (DNMT3A), isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2), as well as Tet oncogene family member 2. This review will summarize the incidence of these mutations, their impact on biochemical functions including epigenetic modification of genomic DNA and their potential usefulness as prognostic indicators. Importantly, the presence of DNMT3A, IDH1 or IDH2 mutations may confer sensitivity to novel therapeutic approaches, including the use of demethylating agents. Therefore, the clinical experience with decitabine and azacitidine in the treatment of patients harboring these mutations will be reviewed. Overall, we propose that understanding the role of these mutations in AML biology will lead to more rational therapeutic approaches targeting molecularly defined subtypes of the disease.

Perturbations of 5-hydroxymethylcytosine patterning in hematologic malignancies

The recent identification of covalent cytosine modifications derived from the metabolism of 5-methylcytosine (5-mC) and catalyzed by the TET proteins has facilitated molecular insight into a new subclass of acute myeloid leukemias (AMLs). TET2-mutant AMLs have the predicted hypermethylation phenotype expected given the inability of the mutant TET2 protein to convert 5-mC to 5-hydroxymethylcytosine (5-hmC). In addition, IDH1/2 mutations confer a gain-of-function, allowing the enzymes to process α-ketoglutarate to 2-hydroxyglutarate, which inhibits the TET proteins and ultimately induces the same hypermethylation phenotype. New techniques are being developed rapidly that have the unprecedented capacity to distinguish among the various covalent cytosine modifications now known to exist. Soon, these methods will be harnessed to yield a new level of insight into AMLs with altered distribution of 5-hmC, information that may allow new diagnostic and therapeutic approaches for patients with this subtype of AML.

Isocitrate dehydrogenase mutations in leukemia

Recent genome-wide discovery studies have identified a spectrum of mutations in different malignancies and have led to the elucidation of novel pathways that contribute to oncogenic transformation. The discovery of mutations in the genes encoding isocitrate dehydrogenase (IDH) has uncovered a critical role for altered metabolism in oncogenesis, and the neomorphic, oncogenic function of IDH mutations affects several epigenetic and gene regulatory pathways. Here we discuss the relevance of IDH mutations to leukemia pathogenesis, therapy, and outcome and how mutations in IDH1 and IDH2 affect the leukemia epigenome, hematopoietic differentiation, and clinical outcome.

Potential application of IDH1 and IDH2 mutations as prognostic indicators in non-promyelocytic acute myeloid leukemia: a meta-analysis

Recurrent mutations of isocitrate dehydrogenase isoforms 1 and 2 (IDH1 and IDH2) have recently been studied in adult patients with acute myeloid leukemia (AML). A meta-analysis was performed to demonstrate their controversial prognostic impacts. The associations of IDH1 or IDH2 mutations with other molecular abnormalities were also investigated. In patients with AML, IDH1/2 mutations were significantly associated with normal karyotype and isolated trisomy 8 (p < .05). After adjusting for well-studied prognostic factors, IDH1 mutation seems to be associated with subtle but significantly inferior event-free survival (EFS) (p = 0.02) and possible adverse overall survival (OS) (p = 0.13) in patients with AML, especially in the favorable genotype subset with mutated NPM1 but without FLT3-ITD mutation (p < 0.05). Longer OS (p = 0.01) and better EFS tendency (p = 0.18) are implicated in patients with IDH2 mutations, which suggests that IDH2 mutations appear to confer a favorable prognosis. Moreover, IDH1 and IDH2 mutations may play a more important role in abnormal cytogenetics subgroups such as isolated trisomy 8. Screening of IDH1/2 mutations could help to identify patients at high risk within some subsets of AML.

Differential prognostic effect of IDH1 versus IDH2 mutations in myelodysplastic syndromes: a Mayo Clinic study of 277 patients

Unlike the case with acute myeloid leukemia, there is limited information on the prognostic impact of isocitrate dehydrogenase (IDH) mutations in myelodysplastic syndromes (MDS). In the current study of 277 patients with MDS, IDH mutations were detected in 34 (12%) cases: 26 IDH2 (all R140Q) and 8 IDH1 (6 R132S and 2 R132C). Mutational frequency was 4% (2 of 56) in refractory anemia with ring sideroblasts, 12% (16 of 130) in refractory cytopenia with multilineage dysplasia, 14% (2 of 14) in MDS-unclassifiable, 14% (6 of 42) in refractory anemia with excess blasts (RAEB)-1 and 23% (8 of 35) in RAEB-2. Normal karyotype was noted in all but one IDH1-mutated cases and 13 IDH2-mutated cases. Multivariable analysis identified presence of mutant IDH1 (P=0.0004; hazard ration 4.0, 95% confidence interval 1.9-8.8), revised International Prognostic Scoring System risk category (P<0.0001), and red cell transfusion need (P=0.002) as independent predictors of inferior survival. In a similar multivariable analysis, mutant IDH1 was the only variable associated with shortened leukemia-free survival (P=0.001; hazard ration 7.0, 95% confidence interval 2.3-20.8). The presence of IDH2R140Q did not affect the overall (P=0.54) or leukemia-free (P=0.81) survival. The current study suggests a powerful adverse prognostic effect for mutant IDH1 in MDS.

IDH1 and IDH2 mutation analysis in Chinese patients with acute myeloid leukemia and myelodysplastic syndrome

The somatic mutations of isocitrate dehydrogenase genes (IDH1 and IDH2) have been identified in a proportion of hematologic malignancies. We examined IDH1 R132 and IDH2 R140/R172 mutations by high resolution melting analysis and direct sequencing in Chinese patients with different myeloid malignancies including 198 acute myeloid leukemia (AML), 82 myelodysplastic syndrome (MDS), 85 chronic myeloid leukemia, and 57 myeloproliferative neoplasms. IDH1 and IDH2 mutations were found in four (2.0%) and ten (5.0%) AML and in two (2.4%) and three (3.6%) MDS cases, but not in other patients. IDH1 and IDH2 mutations were heterozygous and mutually exclusive. IDH1/2 mutations were significantly more frequently observed in cytogenetically normal AML or MDS compared to those without mutations. There was no difference in overall survival of both AML and MDS patients with or without IDH1/2 mutations (P = 0.177 and 0.407, respectively). In conclusion, IDH1/2 mutations are recurrent but rare molecular aberrations in Chinese AML and MDS.

IDH mutations in primary myelofibrosis predict leukemic transformation and shortened survival: clinical evidence for leukemogenic collaboration with JAK2V617F

Isocitrate dehydrogenase (IDH) mutations are frequent in blast-phase myeloproliferative neoplasms and might therefore contribute to leukemic transformation. We examined this possibility in 301 consecutive patients with chronic-phase primary myelofibrosis (PMF). The mutant IDH was detected in 12 patients (4%): 7 IDH2 (5 R140Q, 1 R140W and 1 R172G) and 5 IDH1 (3 R132S and 2 R132C). In all, 6 (50%) of the 12 IDH-mutated patients also expressed JAK2V617F. Overall, 18 (6%) patients displayed only MPL and 164 (54.3%) only JAK2 mutations. Multivariable analysis that accounted for conventional risk factors disclosed inferior overall survival (OS; P=0.03) and leukemia-free survival (LFS; P=0.003) in IDH-mutated patients: OS hazard ratio (HR) was 0.39 (95% confidence interval (95% CI) 0.2–0.75), 0.50 (95% CI 0.27–0.95) and 0.53 (95% CI 0.23–1.2) for patients with no, JAK2 or MPL mutations, respectively. Further analysis disclosed a more pronounced effect for the mutant IDH on OS and LFS in the presence (P=0.0002 and P<0.0001, respectively) as opposed to the absence (P=0.34 and P=0.64) of concomitant JAK2V617F. Analysis of paired samples obtained during chronic- and blast-phase disease revealed the presence of both IDH and JAK2 mutations at both time points. Our observations suggest that IDH mutations in PMF are independent predictors of leukemic transformation and raise the possibility of leukemogenic collaboration with JAK2V617F.

Mutations in epigenetic modifiers in myeloid malignancies and the prospect of novel epigenetic-targeted therapy

In the recent years, the discovery of a series of mutations in patients with myeloid malignancies has provided insight into the pathogenesis of myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), and acute myeloid leukemia (AML). Among these alterations have been mutations in genes, such as IDH1/2, TET2, DNMT3A, and EZH2, which appear to affect DNA and/or histone lysine methylation. Large clinical correlative studies are beginning to decipher the clinical importance, prevalence, and potential prognostic significance of these mutations. Additionally, burgeoning insight into the role of epigenetics in the pathogenesis of myeloid malignancies has prompted increased interest in development of novel therapies which target DNA and histone posttranslational modifications. DNA demethylating agents have been demonstrated to be clinically active in a subset of patients with MDS and AML and are used extensively. However, newer, more specific agents which alter DNA and histone modification are under preclinical study and development and are likely to expand our therapeutic options for these diseases in the near future. Here, we review the current understanding of the clinical importance of these newly discovered mutations in AML and MDS patients. We also discuss exciting developments in DNA methyltransferase inhibitor strategies and the prospect of novel histone lysine methyltransferase inhibitors.

Mutations with epigenetic effects in myeloproliferative neoplasms and recent progress in treatment: Proceedings from the 5th International Post-ASH Symposium

Immediately following the 2010 annual American Society of Hematology (ASH) meeting, the 5th International Post-ASH Symposium on Chronic Myelogenous Leukemia and BCR-ABL1-Negative Myeloproliferative Neoplasms (MPNs) took place on 7–8 December 2010 in Orlando, Florida, USA. During this meeting, the most recent advances in laboratory research and clinical practice, including those that were presented at the 2010 ASH meeting, were discussed among recognized authorities in the field. The current paper summarizes the proceedings of this meeting in BCR-ABL1-negative MPN. We provide a detailed overview of new mutations with putative epigenetic effects (TET oncogene family member 2 (TET2), additional sex comb-like 1 (ASXL1), isocitrate dehydrogenase (IDH) and enhancer of zeste homolog 2 (EZH2)) and an update on treatment with Janus kinase (JAK) inhibitors, pomalidomide, everolimus, interferon-α, midostaurin and cladribine. In addition, the new ‘Dynamic International Prognostic Scoring System (DIPSS)-plus' prognostic model for primary myelofibrosis (PMF) and the clinical relevance of distinguishing essential thrombocythemia from prefibrotic PMF are discussed.