Recurrent Aortic Thromboembolism Associated With TET2 Mutation in Chronic Myelomonocytic Leukemia

Ten-eleven translocation 2 (TET2) plays a pivotal role in epigenetic regulation, cell differentiation, and the inflammatory response. It also mediates the transcriptional regulation for inflammatory cytokines, particularly interleukin-6. While loss-of-function mutation in TET2 has been associated with hematological malignancies, it has been increasingly recognized to cause atherosclerotic disease. The increased atherogenicity is thought to be the result of increased production of pro-inflammatory interleukin-1β cytokines following activation of NLRP3 inflammasomes. We present a unique case of recurrent atherothrombosis in an elderly man who was diagnosed with chronic myelomonocytic leukemia in the setting of TET2 mutation.

Data-driven modeling of core gene regulatory network underlying leukemogenesis in IDH mutant AML

Acute myeloid leukemia (AML) is characterized by uncontrolled proliferation of poorly differentiated myeloid cells, with a heterogenous mutational landscape. Mutations in IDH1 and IDH2 are found in 20% of the AML cases. Although much effort has been made to identify genes associated with leukemogenesis, the regulatory mechanism of AML state transition is still not fully understood. To alleviate this issue, here we develop a new computational approach that integrates genomic data from diverse sources, including gene expression and ATAC-seq datasets, curated gene regulatory interaction databases, and mathematical modeling to establish models of context-specific core gene regulatory networks (GRNs) for a mechanistic understanding of tumorigenesis of AML with IDH mutations. The approach adopts a novel optimization procedure to identify the optimal network according to its accuracy in capturing gene expression states and its flexibility to allow sufficient control of state transitions. From GRN modeling, we identify key regulators associated with the function of IDH mutations, such as DNA methyltransferase DNMT1, and network destabilizers, such as E2F1. The constructed core regulatory network and outcomes of in-silico network perturbations are supported by survival data from AML patients. We expect that the combined bioinformatics and systems-biology modeling approach will be generally applicable to elucidate the gene regulation of disease progression.

TET2 Mutation May Be More Valuable in Predicting Thrombosis in ET Patients Compared to PV Patients: A Preliminary Report

Thrombosis is a common complication of myeloproliferative neoplasm (MPN), and it is a major cause of disability and death. With the development of next-generation gene-sequencing technology, the relationship between non-driver mutations and thrombotic risk factors has also attracted considerable attention. To analyze the risk factors of thrombosis in patients with essential thrombocythemia (ET) and polycythemia vera (PV), we retrospectively analyzed the clinical data of 125 MPN patients (75 ET and 50 PV) and performed a multivariate analysis of the risk factors of thrombosis using a Cox proportional risk model. Among the 125 patients, 35 (28.0%) had thrombotic events, and the incidence of thrombotic events was 21.3% and 38.0% in ET and PV patients, respectively. In ET patients, the multivariate analysis showed that a TET2 mutation and history of remote thrombosis were independent risk factors for thrombosis in ET patients, with an HR of 4.1 (95% CI: 1.40-12.01; p = 0.01) for TET2 mutation and 6.89 (95% CI: 1.45-32.68; p = 0.015) for a history of remote thrombosis. In PV patients, the multivariate analysis presented the neutrophil-to-lymphocyte ratio (NLR) (HR: 4.77, 95% CI: 1.33-17.16; p = 0.017) and a history of remote thrombosis (HR: 1.67, 95% CI: 1.03-1.32; p = 0.014) as independent risk factors for thrombosis, with no significant change in the risk of thrombosis in patients with TET2 mutations. A further analysis of the clinical characteristics and coagulation occurring in ET patients with a TET2 mutation revealed that the values of age and D-dimer were significantly higher and antithrombin III was significantly lower in TET2-mutated ET patients compared to TET2-unmutated patients. In summary, TET2 mutation may be more valuable in predicting thrombosis in ET patients than in PV patients. ET patients with a TET2 mutation are older and present differences in coagulation compared to TET2-unmutated patients.

Increased Apoptotic Activity in Low-Risk Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a heterogeneous hematopoietic disorder associated with cellular proliferative and apoptotic activity. We retrospectively investigated these activities in bone marrow samples from 76 MDS patients using immunohistochemical staining for Ki-67 and cleaved caspase-3. We divided cleaved caspase-3 into two groups based on median value and compared the differences according to MDS risk scoring systems. We compared MDS patient indices with idiopathic cytopenia of undetermined significance (ICUS) and healthy control (HC) indices using our previously published data. Cleaved caspase-3 immunohistochemistry was highest in MDS patients, followed by ICUS patients and HCs. Similarly, the mean Ki-67 grade was also highest in MDS patients, followed by ICUS patients and HCs. Higher cleaved caspase-3 grade was significantly associated with lower IPSS-R score (p = 0.020), whereas Ki-67 was not associated with MDS. Interestingly, TET2 mutation was associated with decreased cleaved caspase-3 levels (p = 0.03). However, there was no significant association between proliferative/apoptotic activity and survival. Our results suggest that apoptotic activity gradually increases from healthy controls and ICUS patients to MDS patients. Furthermore, higher apoptotic activity was associated with better MDS patient prognostic scores. Further studies are needed to reveal the differences in apoptotic activity between lower- and higher-risk MDS.

Detection of TET2 Mutation in Patients with De Novo Acute Myeloid Leukemia: A Mutation Analysis of 51 Iranian Patients

Acute myeloid leukemia (AML) is a heterogeneous clonal disease that is considered to originate from hematopoietic stem cells, which are characterized by impaired myelopoiesis and blast proliferation. TET oncogene family member 2 (TET2) mutations are frequent in myeloid malignancies and several studies have assessed the clinical importance of TET2 mutations. However, its frequency ratio has not yet been fully clarified.

METHOD

Hence, our study was aimed to analyze TET2mut in patients with de-novo AML and their association with clinical, molecular characteristics and Nucleophosmin 1 (NPM1), Fms-like tyrosine kinase 3 (FLT3), CCAAT Enhancer Binding Protein Alpha (CEBPA) and Wilms' tumor protein (WT1) gene expression. Fifty-one Iranian patients were screened by polymerase chain reaction (PCR) and direct sequencing to evaluate TET2 mutations frequency.

RESULTS

Out of all patients, 10 mutations in 8 patients (15.6%) were detected and closely associated with higher age and higher hemoglobin levels (p-value <0.05). Although FLT3, NPM1 and CEBPA gene expression did not show any significant correlation with TET2mut, cytogenetically normal acute myeloid leukemia (CN-AML)  patients appear to bear TET2mut more frequently with lower platelet counts. Monocyte-lineages leukemia has seemed to be more linked with TET2mut in these patients.

CONCLUSION

Our study suggests the frequency of TET2mut in our study (15.6%) is in line with previous studies and reveals the critical role of TET2 in myeloid transformation, especially in leukemia with monocytic subtypes. <br />.

Atypical CML with TET2 mutation, associated with NRAS and KRAS: A case report and literature review

Background

Atypical chronic myeloid leukemia (BCR-ABL1 negative) is a rare myeloid neoplasm with poor prognosis and no current standard of treatment. It features both myelodysplastic and myeloproliferative characteristics with little data regarding mutations playing a role in the disease.

Presentation of case

We present a case of a 55-year-old female complaining of fever, cough, general weakness and night sweats. Examinations showed leukocytosis with a left shift, thrombocytopenia, hypercellular bone marrow with marked granulocytic hyperplasia and a negative BCR-ABL. After ruling out myelodysplastic and other myeloproliferative diseases the patient was finally diagnosed as aCML according to the WHO criteria with mutations in the TET2 gene, the NRAS gene and in the KRAS gene. The patient was started on Hydroxyurea for a duration of 9 months with an excellent initial response leading to normalization of her platelets and WBCs. However, in the last month she stopped responding to therapy and her state of health started declining once again.

Conclusion

Atypical chronic myeloid leukemia (BCR-ABL1 negative with presence of TET2 gene mutation) is an unusual finding in myeloid neoplasms, have unknown prognosis and no current standard of treatment. It features both myelodysplastic and myeloproliferative characteristics with little data regarding mutations playing a role in the disease.

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Atypical CML is challenging to diagnose and can be misdiagnosed with CMML.

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Careful history taking, meticulous physical examination, and investigations are necessary.

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A treatment is not yet stipulated; however, researchers are working on it.

Angioimmunoblastic T-cell lymphoma contains multiple clonal T-cell populations derived from a common TET2 mutant progenitor cell

Angioimmunoblastic T‐cell lymphoma (AITL) is a neoplastic proliferation of T follicular helper cells with clinical and histological presentations suggesting a role of antigenic drive in its development. Genetically, it is characterized by a stepwise acquisition of somatic mutations, with early mutations involving epigenetic regulators (TET2, DNMT3A) and occurring in haematopoietic stem cells, with subsequent changes involving signaling molecules (RHOA, VAV1, PLCG1, CD28) critical for T‐cell biology. To search for evidence of potential oncogenic cooperation between genetic changes and intrinsic T cell receptor (TCR) signaling, we investigated somatic mutations and T‐cell receptor β (TRB) rearrangement in 119 AITL, 11 peripheral T‐cell lymphomas with T follicular helper phenotype (PTCL‐TFH), and 25 PTCL‐NOS using Fluidigm polymerase chain reaction (PCR) and Illumina MiSeq sequencing. We confirmed frequent TET2, DNMT3A, and RHOA mutations in AITL (72%, 34%, 61%) and PTCL‐TFH (73%, 36%, 45%) and showed multiple TET2 mutations (2 or 3) in 57% of the involved AITL and PTCL‐TFH. Clonal TRB rearrangement was seen in 76 cases with multiple functional rearrangements (2–4) in 18 cases (24%). In selected cases, we confirmed bi‐clonal T‐cell populations and further demonstrated that these independent T‐cell populations harboured identical TET2 mutations by using BaseScope in situ hybridization, suggesting their derivation from a common TET2 mutant progenitor cell population. Furthermore, both T‐cell populations expressed CD4. Finally, in comparison with tonsillar TFH cells, both AITL and PTCL‐TFH showed a significant overrepresentation of several TRB variable family members, particularly TRBV19*01. Our findings suggest the presence of parallel neoplastic evolutions from a common TET2 mutant haematopoietic progenitor pool in AITL and PTCL‐TFH, albeit to be confirmed in a large series of cases. The biased TRBV usage in these lymphomas suggests that antigenic stimulation may play an important role in predilection of T cells to clonal expansion and malignant transformation. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

[Diagnosis and treatment of angioimmunoblastic T-cell lymphoma and related cancers]

Gene and protein expression profiling has clarified that tumor cells in angioimmunoblastic T-cell lymphoma (AITL) have T follicular helper (TFH) cell characteristics. In AITL, typical genomic abnormalities have been reported that combine G17V RHOA mutations, gene mutations involved in epigenetic pathways, and those involved in T-cell receptor signal pathways. Besides AITL, some lymphomas display a TFH phenotype, prompting the proposal of a new disease classification encompassing those. Interestingly, lymphomas with TFH phenotype characteristics also share most genomic abnormalities with AITL. Furthermore, because AITL genomic abnormalities are highly disease specific, they can be used for diagnosis. Although AITL is a refractory disease, several new drugs have been approved for relapsed and refractory cases. Precision medicine targeting genomic aberrations characteristic of AITL is being investigated.

The prognostic impact of tet oncogene family member 2 mutations in patients with acute myeloid leukemia: a systematic-review and meta-analysis

Background

The impact of Tet oncogene family member 2 (TET2) mutations on the prognosis of acute myeloid leukemia (AML) is still controversial. A meta analysis is needed in order to assess the prognostic significance of TET2 mutation in AML.

Methods

Five databases including PubMed, Cochrane, EMBase, China National Knowledge Internet (CNKI) and Wanfang database were retrieved to search studies that investigated the correlation between TET2 mutations and outcomes of AML patients. Pooled hazard ratios (HRs) and odds ratios (ORs) were used to assess the effects of TET2 mutations.

Results

Sixteen studies were included. TET2 mutation was an unfavorable prognostic factor for overall survival (OS: HR = 1.386; P < 0.001) and event-free survival (EFS: HR = 1.594; P = 0.002) in patients with AML. For patients under 65 years of age, TET2 mutation predicted an inferior OS (HR = 1.310, P = 0.051) and EFS (HR = 1.429, P = 0.027). For patients with intermediate-risk cytogenetics (IR-AML), mutant TET2 had a significant association with adverse OS (HR = 0.474; P < 0.001). For patients with normal cytogenetics (CN-AML), mutant TET2 also conferred adverse OS (HR = 1.425; P < 0.001) and EFS (HR = 1.450, P < 0.001). Further, among patients with CN-AML, mutant TET2 was associated with inferior OS (HR = 2.034, P < 0.001) and EFS (HR = 2.140, P < 0.001) in the ELN favorable-risk subgroup and an inferior EFS (HR = 1.487; P < 0.001) in the ELN intermediate-Isubgroup. With respect to treatment outcome, TET2 mutation predicted a significantly lower rate of complete remission (CR) in cases with ELN favorable-risk cytogenetics (OR = 0.460, P = 0.011).

Conclusions

TET2 mutation had adverse impacts on survival and treatment response in AML patients and will contribute to risk-stratification, prognosis prediction and therapy guidance.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5602-8) contains supplementary material, which is available to authorized users.

Prognostic role of TET2 deficiency in myelodysplastic syndromes: A meta-analysis

Tet methylcytosine dioxygenase2 gene (TET2) is one of the most frequently mutated gene in myeloid neoplasm, but the prognostic role of TET2 aberrations in myelodysplastic syndromes (MDS) remains unclear. Therefore, we performed a meta-analysis. Fourteen eligible studies with 1983 patients were included in this meta-analysis. Among these, 2 studies evaluated the impact that the TET2 expression level had on the prognosis. The combined hazard ratios (HR) estimated for overall survival (OS) was 1.00 (95%CI: 0.74 to 1.37; p=0.989) when comparing those with TET2 mutations with those without. Among the patients treated with hypomethylating agents (HMAs) or hematopoietic stem cell transplantation (HSCT), the pooled HR for OS was 1.02 (95% CI: 0.77-1.35, p=0.89) and 1.54 (95%CI: 0.69 to 3.44; p=0.29), respectively. We also conducted an analysis of the response rate to HMAs, and the OR was 1.73 (95%CI: 1.11 to 2.70; p=0.016). Additionally, subgroup analyses showed the pooled HR for OS was 0.93(95%CI: 0.44 to 1.98; P=0.849) in WHO-classified CMML patients and 1.02(95%CI: 1.02 to 3.46; p=0.042) in studies evaluated TET2 expression level. The analysis suggested TET2 mutations had no significant prognostic value on MDS. However, the response rates to HMAs were significantly different between those with and without TET2 mutations, and the low expression level of TET2 gene was significantly associated with a poor OS in MDS patients.

BCL6 locus is hypermethylated in angioimmunoblastic T-cell lymphoma

BCL6, a master transcription factor for differentiation of follicular helper T (TFH) cells, is highly expressed in angioimmunoblastic T-cell lymphoma (AITL) and peripheral T-cell lymphomas (PTCL) containing tumor cells with TFH features. TET2, encoding an epigenetic regulator, is frequently mutated in AITL/PTCL. We previously reported that Tet2 knockdown mice developed T-cell lymphomas with TFH features. Hypermethylation of the Bcl6 locus followed by BCL6 upregulation was thought to be the key event for lymphoma development in mice. The mechanisms by which BCL6 expression is upregulated in human AITL/PTCL, however, have not been elucidated. Here, we investigated the impact of TET2 mutations on methylation of BCL6 locus in human AITL/PTCL samples. Hypermethylation of the BCL6 locus was more frequent in PTCL samples than B-cell lymphoma samples (PTCL vs B-cell lymphomas: 9/42 vs 0/35). PTCL samples with TET2 mutations were more frequently hypermethylated than those without TET2 mutations (PTCL with TET2 mutations vs without mutations: 6/22 vs 0/17). BCL6 expression in hypermethylated samples was higher than that in low methylated samples. Deregulated BCL6 expression caused by hypermethylation and TET2 mutations may result in skewed TFH differentiation and eventually contribute to AITL/PTCL development in patients, as well as lymphoma development in Tet2 knockdown mice.

Identifying Inherited and Acquired Genetic Factors Involved in Poor Stem Cell Mobilization and Donor-Derived Malignancy

Analysis of the clinical characteristics of hematopoietic stem cell transplant (HSCT) donors has proven beneficial for identifying cases of heritable hematopoietic disorders. This study examines poor peripheral blood hematopoietic stem cell mobilization after granulocyte colony-stimulating factor administration among 328 donors as a potential marker for suspected familial predisposition to myeloid malignancies. Here, we present data comparing the clinical characteristics of poor-mobilizing versus nonpoor-mobilizing donors and the results of panel-based sequencing of hematopoietic genes in poor-mobilizing donors. From this analysis, we identified a novel case of a donor-derived myelodysplastic syndrome in an HSCT recipient that is consistent with clonal evolution of TET2-mutated clonal hematopoiesis of indeterminate potential (CHIP) within the donor. This study demonstrates the potential risk of using hematopoietic stem cells from a donor with CHIP and raises the question of whether there should be increased screening measures to identify such donors.

Discordant intracellular and plasma D-2-hydroxyglutarate levels in a patient with IDH2 mutated angioimmunoblastic T-cell lymphoma

OBJECTIVES

Angioimmunoblastic T-cell lymphoma (AITL) is an aggressive peripheral T-cell lymphoma with mutations in genes encoding isocitrate dehydrogenase1 and 2 (IDH1 and IDH2). Mutant IDH generates the oncometabolite D-2-hydroxyglutarate (D-2HG). We report the first case of discordant intracellular and plasma D-2HG levels in a patient with IDH2 R172S mutated AITL.

METHODS

An 87-year-old woman was diagnosed with AITL in the groin lymph node by morphologic and immunophenotypic analyses, and molecular studies by DNA sequencing. D-2HG was measured in both tumoral tissue and in pre-treatment plasma by liquid chromatography-tandem mass spectrometry.

RESULTS

While D-2HG was markedly elevated in the tissue sample, its level in plasma was normal. We discuss this discordant D-2HG result within the context of previously reported discordant 2HG results in other IDH mutated tumors, and its implication for using circulating D-2HG as a biomarker of IDH mutation. In addition, this case also harbored mutations in RHOA, TET2, and TP53. The molecular pathogenesis is briefly discussed.

CONCLUSION

While our case suggests that circulating D-2HG is not a reliable marker of IDH mutation in AITL, more cases need to be studied to arrive at a definite conclusion.

Genome sequencing in myelodysplastic syndromes: can molecular mutations predict benefit from hypomethylating agent therapy?

Evaluation of: Bejar R, Lord A, Stevenson K, et al. TET2 mutations predict response to hypomethylating agents in myelodysplastic syndrome patients. Blood 2014 Oct 23;124(17):2705-12. Patients with myelodysplastic syndromes (MDS) have clinically variable courses even within the same prognostic subgroups. Although hypomethylating agents (HMAs) have been shown to improve outcomes in patients with high-risk MDS, many patients do not derive benefit. There is an urgent clinical need to identify patients with low probability of benefiting from HMAs but no reliable clinical predictors or biomarkers have been discovered to date. Although some recurrent molecular mutations in MDS carry independent prognostic value, their ability to predict benefit from HMAs is not clear. Here, we discuss an important article in which sequencing from samples of 213 patients identified recurrent mutations associated with response to HMAs. Although an important step in the right direction, the clinical implications of these findings are far from optimal and identification of biomarkers that can reliably predict benefit from HMAs and other therapies in patients with MDS remains a top clinical and a research priority.