Novel mutations and their functional and clinical relevance in myeloproliferative neoplasms: JAK2, MPL, TET2, ASXL1, CBL, IDH and IKZF1

Therapeutic potential of anticancer activity of nitrogen-containing heterocyclic scaffolds as Janus kinase (JAK) inhibitor: Biological activity, selectivity, and structure-activity relationship

The JAK-STAT signalling pathway is primarily involved in cytokine signalling and induces various factors namely, erythropoietin, thrombopoietin, interferons, interleukins, and granulocyte colony-stimulating factors. These factors tremendously influenced understanding human health and illness, specifically cancer. Inhibiting the JAK/STAT pathway offers enormous therapeutic promises against cancer. Many JAK inhibitors are now being studied due to their efficacy in various cancer treatments. Further, the Nitrogen-heterocyclic (N-heterocyclic) scaffold has always shown to be a powerful tool for designing and discovering synthetic compounds with diverse pharmacological characteristics. The review focuses on several FDA-approved JAK inhibitors and their systematic categorization. The medicinal chemistry perspective is highlighted and classified review on the basis of N-heterocyclic molecules. Several examples of designing strategies of N-heterocyclic rings including pyrrolo-azepine, purine, 1H-pyrazolo[3,4-d]pyrimidine, 1H-pyrrolo[2,3-b]pyridine, pyrazole, thieno[3,2-d] pyrimidine, and, pyrimidine-based derivatives and their structure-activity relationships (SAR) are discussed. Among the various N-heterocyclic-based JAK inhibitors pyrimidine-containing compound 1 exhibited excellent inhibition activity against JAK2WT and mutated-JAK2V617F with IC50 of 2.01 and 18.84 nM respectively. Amino pyrimidine-containing compound 6 and thiopheno[3,2-d]pyrimidine-containing compound 13 expressed admirable JAK3 inhibition activity with IC50 of 1.7 nM and 1.38 nM respectively. Our review will support the medicinal chemists in refining and directing the development of novel N-heterocyclic-based JAK inhibitors.

TLR2 Derangements Likely Play a Significant Role in the Inflammatory Response and Thrombosis in Patients with Ph(-) Classical Myeloproliferative Neoplasm

We investigated the role of toll-like receptors (TLRs) in inflammatory pathways in Philadelphia chromosome-negative myeloproliferative neoplasms (Ph(-)MPNs). TLR2 expression was increased in ET, PV, and MPN (grouped as (PV + (ET) + MF)), whereas TLR4 was elevated only in MPN. TLR3, 7, and 9 were not elevated. Cultured monocyte-derived dendritic cells and plasma assays in TLR2-elevated patients were found to secrete more cytokines than those from TLR2-normal patients. These facts suggest that TLR2 is the major inflammatory pathways in MPN. We also measured S100A9 and reactive oxygen species (ROS), revealing increased S100A9 in PV, MF, and MPN, while ROS were only increased in MF. These data suggests that MPNs initially involve TLR2, with minor contributions from TLR4, and with S100A9, leading to ROS formation, JAK2 mutation, and progression to MF or leukemia. Furthermore, patients with JAK2 mutations or leukocytosis exhibited higher TLR2 expression. In leukocyte-platelet interactions, cells from MPN patients displayed a stronger response to a TLR2 agonist than TLR4 agonist. A TLR2 inhibitor (but not a TLR4 inhibitor) attenuated this response. Thrombosis incidence was higher in TLR2-elevated patients (29%) than in TLR2-normal patients (19%). These findings suggest that TLR2 likely contributes to thrombosis in MPN.

STAT5a and SH2B3 novel mutations display malignancy roles in a triple-negative primary myelofibrosis patient

Primary myelofibrosis (PMF) patients frequently have JAK2 (V617F), CALR (exon 9), or MPL (W515 or exon 10) strong driver gene mutation, which triggers abnormal activation of the JAK2-STATs signaling pathway that plays a complex role in the occurrence of PMF. However, about 10-15% of PMF patients have no above typical mutations in these strong driver genes, known as being "triple-negative", which are associated with poor prognosis. In this paper, we reported a unique secondary acute myeloid leukemia (sAML) case transformed from triple-negative PMF combined with lung cancer and erythroderma occurrence at the same time, which has not been reported so far. Through whole blood exome sequencing, four novel noncanonical mutations were detected in key regulatory genes SH2B3 (Q748 and S710) and STAT5a (C350 and K354). Meanwhile, STAT5a-S710 and SH2B3-K354 noncanonical mutations gained strong malignant biofunction on promoting cell growth and tumorigenesis by accelerating the G1/S transition. In the mechanistic study, these pernicious phenotypes driven by noncanonical mutations might be initial PMF by activating p-STAT5a/c-Myc/CyclinD1 and p-STAT3/p-AKT/p-ERK1/2 signaling axes. Therefore, our study explored the deleterious roles of novel noncanonical mutations in STAT5a and SH2B3, which may serve as susceptibility genes and display the oncogenic biofunction in the progression of PMF to acute myeloid leukemia-M2a (AML-M2a).

High-risk and silent clonal hematopoietic genotypes in patients with nonhematologic cancer

ABSTRACT

Clonal hematopoiesis (CH) identified by somatic gene variants with variant allele fraction (VAF) ≥ 2% is associated with an increased risk of hematologic malignancy. However, CH defined by a broader set of genotypes and lower VAFs is ubiquitous in older individuals. To improve our understanding of the relationship between CH genotype and risk of hematologic malignancy, we analyzed data from 42 714 patients who underwent blood sequencing as a normal comparator for nonhematologic tumor testing using a large cancer-related gene panel. We cataloged hematologic malignancies in this cohort using natural language processing and manual curation of medical records. We found that some CH genotypes including JAK2, RUNX1, and XPO1 variants were associated with high hematologic malignancy risk. Chronic disease was predicted better than acute disease suggesting the influence of length bias. To better understand the implications of hematopoietic clonality independent of mutational function, we evaluated a set of silent synonymous and noncoding mutations. We found that silent CH, particularly when multiple variants were present or VAF was high, was associated with increased risk of hematologic malignancy. We tracked expansion of CH mutations in 26 hematologic malignancies sequenced with the same platform. JAK2 and TP53 VAF consistently expanded at disease onset, whereas DNMT3A and silent CH VAFs mostly decreased. These data inform the clinical and biological interpretation of CH in the context of nonhematologic cancer.

JAK/STAT in leukemia: a clinical update

Over the past three decades, considerable efforts have been expended on understanding the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in leukemia, following the identification of the JAK2V617F mutation in myeloproliferative neoplasms (MPNs). The aim of this review is to summarize the latest progress in our understanding of the involvement of the JAK/STAT signaling pathway in the development of leukemia. We also attempt to provide insights into the current use of JAK/STAT inhibitors in leukemia therapy and explore pertinent clinical trials in this field.

Differences in Clinical Outcomes Between Hydroxyurea-Resistant and -Intolerant Polycythemia Vera Patients

BACKGROUND

Previous studies have suggested that patients with polycythemia vera (PV) who exhibit hydroxyurea-resistance (HU-R) and -intolerance (HU-I) may have distinct characteristics and clinical outcomes. However, to date, no studies have reported a comparison between these two groups or assessed prognostic factors in these patients.

METHODS

The objective of this study was to evaluate clinical outcomes and identify prognostic factors among PV patients with HU-R or HU-I. We conducted a review of PV patients who received frontline treatment with HU from nine centers and identified 90 patients with HU-R or HU-I.

RESULTS

The cumulative incidence of thrombosis after 7 years of HU-R/I was 21.4%, and the incidence of disease progression was 22.5%. Comparing the HU-R and HU-I groups, the HU-R group had a significantly higher rate of disease progression (36.7% vs. 0.56%, P = 0.009), while there was no significant difference in thrombosis incidence (19.0% vs. 22.9%, P = 0.463). Multivariate analysis revealed that HU-R was an independent prognostic factor for progression-free survival (hazard ratio, 6.27, 95% confidence interval, 1.83-21.47, P = 0.003). Additionally, higher lactate dehydrogenase levels, multiple cardiovascular risk factors, and prior thrombosis were identified as unfavorable predictors of overall survival.

CONCLUSION

These findings suggest that patients with HU-R face a higher risk of hematological transformation, but have a comparable risk of thrombosis to patients with HU intolerance. These distinctions should guide decisions on second-line treatment options and clinical trials involving these patients.

[Mastocytosis-a frequently unrecognized disease]

Mastocytosis is a rare disease characterized by clonal expansion and accumulation of mast cells (MC) in various organs. Mastocytosis results from an activating mutation of the KIT surface receptor leading to an increased proliferation of MC. There are significant differences between children and adult patients with mastocytosis. Children mainly present the cutaneous form, whereas adults more often exhibit the systemic form of mastocytosis. Patients with mastocytosis may be asymptomatic or affected by a variety of symptoms. Treatment is primarily supportive and aims at symptom control. New approved targeted therapies such as midostaurin and avapritinib changed the treatment paradigm in advanced forms of the disease, and next-generation inhibitors currently in clinical trials are expected in the near future.

Expanded molecular detection of MPL codon p.W515 and p.S505N mutations in myeloproliferative neoplasms

BACKGROUND

Patients negative for the JAK2 p.V617F somatic variant are frequently reflexed to testing for MPL exon 10 variants. Detection of these variants via multiplexed allele-specific PCR followed by fragment analysis has been previously published. The present study builds on this concept by improving the detection of the p.W515A variant, adding a second allele-specific primer to detect the p.W515R variant, and incorporating an improved primer for p.S505N detection.

METHODS

The W515 amplification employs 5'-labeled allele-specific forward primers to detect p.W515K, p.W515L, p.W515R, and p.W515A. The p.S505N amplification includes an allele-specific reverse primer with a tail extension. Fragments were subject to capillary electrophoresis on an ABI 3500 Genetic Analyzer and analyzed using GeneMapper 6.0 (Thermo Fisher Scientific).

RESULTS

Thirty MPL-negative and 13 MPL-positive samples previously tested by a reference laboratory were tested with the MPL LDT. Results were 100% concordant. The MPL LDT has a limit of detection of at least 5% VAF for the p.W515 variants and 10% VAF for the p.S505N variant.

CONCLUSION

Current MPL assays are predominantly focused on p.W515L/K and p.S505N mutations. We have engineered an MPL test for detecting p.W515A/L/K/R and p.S505N variants, thereby increasing the diagnostic yield with little additional expense or technician time.

Management of classical Philadelphia chromosome-negative myeloproliferative neoplasms in Asia: consensus of the Asian Myeloid Working Group

Myeloproliferative neoplasms (MPN) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized clinically by the proliferation of one or more hematopoietic lineage(s). The classical Philadelphia-chromosome (Ph)-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The Asian Myeloid Working Group (AMWG) comprises representatives from fifteen Asian centers experienced in the management of MPN. This consensus from the AMWG aims to review the current evidence in the risk stratification and treatment of Ph-negative MPN, to identify management gaps for future improvement, and to offer pragmatic approaches for treatment commensurate with different levels of resources, drug availabilities and reimbursement policies in its constituent regions. The management of MPN should be patient-specific and based on accurate diagnostic and prognostic tools. In patients with PV, ET and early/prefibrotic PMF, symptoms and risk stratification will guide the need for early cytoreduction. In younger patients requiring cytoreduction and in those experiencing resistance or intolerance to hydroxyurea, recombinant interferon-α preparations (pegylated interferon-α 2A or ropeginterferon-α 2b) should be considered. In myelofibrosis, continuous risk assessment and symptom burden assessment are essential in guiding treatment selection. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in MF should always be based on accurate risk stratification for disease-risk and post-HSCT outcome. Management of classical Ph-negative MPN entails accurate diagnosis, cytogenetic and molecular evaluation, risk stratification, and treatment strategies that are outcome-oriented (curative, disease modification, improvement of quality-of-life).

Frequency and prognostic influence of ASXL1 mutations and its potential association with BCR-ABL1 transcript type and smoke in chronic myeloid leukemia patients

BACKGROUND

Heterogeneous response to tyrosine kinase inhibitors (TKIs) and progress to advance phases, still is a significant clinical problem. These are attributed to additional mutations in mutated non-ABL1 genes. we aimed to determine prognostic effects of ASXL1 mutations as a biomarker for diverse treatment response and disease progression to aid clinical management.

METHODS

We performed ASXL1 gene mutational screening in 80 Ph+CML patients at different phases and 10 healthy control by direct sequencing method. Multiplex and qRT-PCR, standard chromosome banding analysis were used to determine BCR-ABL1 transcript type, molecular and cytogenetic responses respectively.

RESULTS

overall, four type mutations were identified in 11.25% of the patients. There was significant difference regarding mutation frequency between chronic and advance phases (P = 0.0002), sokal risk score (P = 0.0001), smoking (P = 0.02) and mean of during time of imatinib treatment (P = 0.009) between patients with and without ASXL1 mutations. ASXL1 mutations frequency had a bias toward younger than older and women than men, but no significant (P > 0.05). ASXL1 mutations were found more recurrently in patients carrying ABL1 KD mutations (P = 0.003). The risk of increasing resistance and disease progression in patients with ASXL1 mutations was 32 and 63 fold higher than those without mutations respectively (P = 0.01; P = 0.0002). The risk of ASXL1 mutations presence in patients with b2a2 transcript type was much higher than b3a2 type (P = 0.02, OR = 10).

CONCLUSION

Our findings suggest that ASXL1 mutations may be favorable predictive biomarkers to determine the best TKI for each patient, and to prevent CML progression.

The JAK2V617F mutation and the role of therapeutic agents in alleviating myeloproliferative neoplasm symptom burden

Alleviating symptom burden in patients with myeloproliferative neoplasms (MPNs) is imperative to achieving optimal management. Research remains to elucidate the relationship between the JAK2V617F (Janus kinase 2) mutation present in many MPN patients, and the symptomatology they experience. This retrospective study analysed data collected from MPN patients included in the Myeloproliferative Neoplasms: An In-depth Case-Control (MOSAICC) pilot study. The MPN Symptom Assessment Form was administered, and median symptom scores were compared between JAK2V617F-positive and JAK2V617F-negative groups. Multivariate logistic regression analysis adjusted for confounding variables. Overall, 106 MPN patients participated: 65.1% were JAK2V617F positive, 30.2% were JAK2V617F negative and 4.7% had an unknown status. Multivariate analysis revealed a low symptom burden for early satiety (p < 0.01), dizziness (p < 0.05), cough (p < 0.05) and bone pain (p < 0.01) in those receiving venesection alone. Interferon alpha was significantly associated (p < 0.05) with severe burden for 16 of the 27 symptoms. JAK2V617F-positive females experienced a greater symptom burden than JAK2V617F-positive males. There was no discernible relationship between the JAK2V617F mutation and symptom burden in MPN patients, unlike the therapeutic agents investigated. Larger studies are required to validate these results and identify mechanisms of symptom development and control in MPN patients.

The telomerase inhibitor imetelstat differentially targets JAK2V617F versus CALR mutant myeloproliferative neoplasm cells and inhibits JAK-STAT signaling

Imetelstat shows activity in patients with myeloproliferative neoplasms, including primary myelofibrosis (PMF) and essential thrombocythemia. Here, we describe a case of prolonged disease stabilization by imetelstat treatment of a high-risk PMF patient enrolled into the clinical study MYF2001. We confirmed continuous shortening of telomere length (TL) by imetelstat treatment but observed emergence and expansion of a KRAST58I mutated clone during the patient's clinical course. In order to investigate the molecular mechanisms involved in the imetelstat treatment response, we generated induced pluripotent stem cells (iPSC) from this patient. TL of iPSC-derived hematopoietic stem and progenitor cells, which was increased after reprogramming, was reduced upon imetelstat treatment for 14 days. However, while imetelstat reduced clonogenic growth of the patient's primary CD34+ cells, clonogenic growth of iPSC-derived CD34+ cells was not affected, suggesting that TL was not critically short in these cells. Also, the propensity of iPSC differentiation toward megakaryocytes and granulocytes was not altered. Using human TF-1MPL and murine 32DMPL cell lines stably expressing JAK2V617F or CALRdel52, imetelstat-induced reduction of viability was significantly more pronounced in CALRdel52 than in JAK2V617F cells. This was associated with an immediate downregulation of JAK2 phosphorylation and downstream signaling as well as a reduction of hTERT and STAT3 mRNA expression. Hence, our data demonstrate that imetelstat reduces TL and targets JAK/STAT signaling, particularly in CALR-mutated cells. Although the exact patient subpopulation who will benefit most from imetelstat needs to be defined, our data propose that CALR-mutated clones are highly vulnerable.

Comprehensive Next-Generation Sequencing Testing in a Patient with TEMPI Syndrome

TEMPI syndrome is a new and poorly understood disease that is currently considered a type of plasma cell neoplasm with paraneoplastic manifestations. The TEMPI acronym defines the hallmarks of the syndrome: T for telangiectasia; E for erythrocytosis with elevated erythropoietin; M, monoclonal gammopathy; P, perinephric collections; and I, intrapulmonary shunting. Due to the marked erythrocytosis as the most common presenting feature, TEMPI is often misdiagnosed as polycythemia vera. However, unlike polycythemia vera, TEMPI is not associated with a JAK2 mutation. The pathogenesis of TEMPI syndrome is unknown, although a few hypothetical disease mechanisms have been previously discussed. Here we present a new case of TEMPI syndrome, discuss results of a next-generation sequencing (NGS) panel covering 1,425 known cancer-related genes, and review the current literature with focus on an update of the genetics of TEMPI syndrome. This is the first report of TEMPI that includes results of comprehensive NGS testing.

Effect of hypoxia on HIF-1α and NOS3 expressions in CD34+ cells of JAK2V617F-positive myeloproliferative neoplasms

PURPOSE

Myeloproliferative neoplasms (MPN) are a heterogeneous group of hematopoietic stem-cell diseases with excessive proliferation of one or more blood cell lines. In this study, we evaluated the effect of different oxygen concentrations on HIF-1α and NOS3 gene expression to determine the effect of the bone marrow microenvironment on JAK2V617F positive Philadelphia chromosome negative (Ph-) MPNs.

PATIENTS AND METHODS

Peripheral blood mononuclear cells (MNC) of 12 patients with Ph- MPN were collected. The presence of JAK2V617F allele status was determined with allele-specific nested PCR analysis. MPN CD34+ and CD34depleted populations were isolated from MNC by magnetic beads. Separate cell cultures of CD34+/depleted populations were managed at different oxygen concentrations including anoxia (∼0%), hypoxia (∼3%), and normoxia (∼20%) conditions for 24 ​h. HIF-1α and NOS3 gene expression changes were examined in each population related to JAK2V617F status with real time RT-PCR.

RESULT

It was revealed that relative HIF-1α and NOS3 expressions were significantly increased in response to decreased oxygen concentration in all samples. Relative HIF-1α and NOS3 expressions were found to be higher especially in CD34+ and CD34depleted populations carrying JAK2V617F mutations compared to MPN patients carrying wild-type JAK2.

CONCLUSION

JAK2V617F might have specific role in HIF-1α and NOS3 regulations with respect to low oxygen concentrations in Ph- MPN. Further evaluations might reveal the effect of JAK2V617F on Ph- MPN pathogenesis in bone marrow microenvironment.

Individual with concurrent chest wall tuberculosis and triple-negative essential thrombocythemia: A case report

BACKGROUND

Chest wall tuberculosis (TB) and triple-negative essential thrombocythemia (TN-ET) are rare medical conditions, and their combination is extremely rare globally. Only one case of TB peritonitis with thrombocytosis has been reported, which was identified in 1974.

CASE SUMMARY

Herein, we report the case of a 23-year-old man with concurrent chest wall mass and TN-ET. The patient presented to a local hospital due to having a headache and low-grade fever for 2 d, with their bodily temperature fluctuating at around 36.8 °C. Hematological analysis showed a high platelet count of 1503 × 109/L. Subsequently, the patient visited our hospital for further investigation. Computed tomography of the chest suggested a submural soft tissue density shadow in the left lower chest wall. After surgical resection, the pathological findings of the swelling were reported as TB with massive caseous necrosis. According to the World Health Organization diagnostic criteria, the patient was diagnosed with TN-ET, as they met the requirement of four main criteria or the first three main criteria and one secondary criterion. The patient was eventually diagnosed with chest wall TB with TN-ET, which is extremely rare.

CONCLUSION

Chest wall TB is rare. TN-ET diagnosis requires secondary factor exclusion and satisfaction of primary diagnostic criteria. miRNA, combined with the methylation process, could explain suppressor of cytokine signaling (SOCS) 1 and SOCS3 downregulation in ET-JAK2V617F-negative patients. The miRNA could participate in JAK2 pathway activation. SOCS3 may be a novel MPN biomarker.

Individual with concurrent chest wall tuberculosis and triple-negative essential thrombocythemia: A case report

BACKGROUND

Chest wall tuberculosis (TB) and triple-negative essential thrombocythemia (TN-ET) are rare medical conditions, and their combination is extremely rare globally. Only one case of TB peritonitis with thrombocytosis has been reported, which was identified in 1974.

CASE SUMMARY

Herein, we report the case of a 23-year-old man with concurrent chest wall mass and TN-ET. The patient presented to a local hospital due to having a headache and low-grade fever for 2 d, with their bodily temperature fluctuating at around 36.8 °C. Hematological analysis showed a high platelet count of 1503 × 10⁹/L. Subsequently, the patient visited our hospital for further investigation. Computed tomography of the chest suggested a submural soft tissue density shadow in the left lower chest wall. After surgical resection, the pathological findings of the swelling were reported as TB with massive caseous necrosis. According to the World Health Organization diagnostic criteria, the patient was diagnosed with TN-ET, as they met the requirement of four main criteria or the first three main criteria and one secondary criterion. The patient was eventually diagnosed with chest wall TB with TN-ET, which is extremely rare.

CONCLUSION

Chest wall TB is rare. TN-ET diagnosis requires secondary factor exclusion and satisfaction of primary diagnostic criteria. miRNA, combined with the methylation process, could explain suppressor of cytokine signaling (SOCS) 1 and SOCS3 downregulation in ET-JAK2V617F-negative patients. The miRNA could participate in JAK2 pathway activation. SOCS3 may be a novel MPN biomarker.

Evolving cognition of the JAK-STAT signaling pathway: autoimmune disorders and cancer

The Janus kinase (JAK) signal transducer and activator of transcription (JAK-STAT) pathway is an evolutionarily conserved mechanism of transmembrane signal transduction that enables cells to communicate with the exterior environment. Various cytokines, interferons, growth factors, and other specific molecules activate JAK-STAT signaling to drive a series of physiological and pathological processes, including proliferation, metabolism, immune response, inflammation, and malignancy. Dysregulated JAK-STAT signaling and related genetic mutations are strongly associated with immune activation and cancer progression. Insights into the structures and functions of the JAK-STAT pathway have led to the development and approval of diverse drugs for the clinical treatment of diseases. Currently, drugs have been developed to mainly target the JAK-STAT pathway and are commonly divided into three subtypes: cytokine or receptor antibodies, JAK inhibitors, and STAT inhibitors. And novel agents also continue to be developed and tested in preclinical and clinical studies. The effectiveness and safety of each kind of drug also warrant further scientific trials before put into being clinical applications. Here, we review the current understanding of the fundamental composition and function of the JAK-STAT signaling pathway. We also discuss advancements in the understanding of JAK-STAT-related pathogenic mechanisms; targeted JAK-STAT therapies for various diseases, especially immune disorders, and cancers; newly developed JAK inhibitors; and current challenges and directions in the field.

[Clinical and genetic characteristics of young patients with myeloproliferative neoplasms]

Objectives: To investigate the clinical and genetic features of young Chinese patients with myeloproliferative neoplasms (MPN). Methods: In this cross-sectional study, anonymous questionnaires were distributed to patients with MPN patients nationwide. The respondents were divided into 3 groups based on their age at diagnosis: young (≤40 years) , middle-aged (41-60 years) , and elderly (>60 years) . We compared the clinical and genetic characteristics of three groups of MPN patients. Results: 1727 assessable questionnaires were collected. There were 453 (26.2%) young respondents with MPNs, including 274 with essential thrombocythemia (ET) , 80 with polycythemia vera (PV) , and 99 with myelofibrosis. Among the young group, 178 (39.3%) were male, and the median age was 31 (18-40) years. In comparison to middle-aged and elderly respondents, young respondents with MPN were more likely to present with a higher proportion of unmarried status (all P<0.001) , a higher education level (all P<0.001) , less comorbidity (ies) , fewer medications (all P<0.001) , and low-risk stratification (all P<0.001) . Younger respondents experienced headache (ET, P<0.001; PV, P=0.007; MF, P=0.001) at diagnosis, had splenomegaly at diagnosis (PV, P<0.001) , and survey (ET, P=0.052; PV, P=0.063) . Younger respondents had fewer thrombotic events at diagnosis (ET, P<0.001; PV, P=0.011) and during the survey (ET, P<0.001; PV, P=0.003) . JAK2 mutations were found in fewer young people (ET, P<0.001; PV, P<0.001; MF, P=0.013) ; however, CALR mutations were found in more young people (ET, P<0.001; MF, P=0.015) . Furthermore, mutations in non-driver genes (ET, P=0.042; PV, P=0.043; MF, P=0.004) and high-molecular risk mutations (ET, P=0.024; PV, P=0.023; MF, P=0.001) were found in fewer young respondents. Conclusion: Compared with middle-aged and elderly patients, young patients with MPN had unique clinical and genetic characteristics.

Leukocytosis and MPNs: Where do we stand?

The Philadelphia-negative myeloproliferative neoplasms (MPNs)-essential thrombocythemia (ET), polycythemia vera (PV) and myelofibrosis (MF), are characterized by a propensity for thrombotic events and variable risks for transformation to MF (for ET and PV) and acute leukemia. Leukocytosis, which serves a minor criterion for the diagnosis of MF, is present in a significant portion of patients with MPNs. The relation and impact of leukocytosis on disease course and outcomes of patients with MPNs has been studied in multiple, large retrospective and prospective studies. Despite this, the association of leukocytosis and thrombosis, fibrosis and leukemic transformation remains unclear. This article details the published investigations regarding the impact of leukocytosis in MPNs and explores the changing role of leukocytosis in disease prognostication as increasing emphasis is placed on molecular and genetic studies.

New Insights into the Pathogenesis of Mastocytosis: Emerging Concepts in Diagnosis and Therapy

Mastocytosis is a heterogeneous group of neoplasms defined by a numerical increase and accumulation of clonal mast cells (MCs) in various organ systems. The disease may present as cutaneous mastocytosis or systemic mastocytosis (SM). On the basis of histopathological and molecular features, clinical variables, and organ involvement, SM is divided into indolent SM, smoldering SM, SM with an associated hematologic neoplasm, aggressive SM, and MC leukemia. Each variant is defined by unique diagnostic criteria and a unique spectrum of clinical presentations. A key driver of MC expansion and disease evolution is the oncogenic machinery triggered by mutant forms of KIT. The genetic background, additional somatic mutations, and comorbidities also contribute to the course and prognosis. Patients with SM may also suffer from mediator-related symptoms or even an MC activation syndrome. This article provides an update of concepts on the genetics, etiology, and pathology of mastocytosis, with emphasis on diagnostic criteria and new treatment concepts.

Germline-somatic JAK2 interactions are associated with clonal expansion in myelofibrosis

Myelofibrosis is a rare myeloproliferative neoplasm (MPN) with high risk for progression to acute myeloid leukemia. Our integrated genomic analysis of up to 933 myelofibrosis cases identifies 6 germline susceptibility loci, 4 of which overlap with previously identified MPN loci. Virtual karyotyping identifies high frequencies of mosaic chromosomal alterations (mCAs), with enrichment at myelofibrosis GWAS susceptibility loci and recurrently somatically mutated MPN genes (e.g., JAK2). We replicate prior MPN associations showing germline variation at the 9p24.1 risk haplotype confers elevated risk of acquiring JAK2^V617F mutations, demonstrating with long-read sequencing that this relationship occurs in cis. We also describe recurrent 9p24.1 large mCAs that selectively retained JAK2^V617F mutations. Germline variation associated with longer telomeres is associated with increased myelofibrosis risk. Myelofibrosis cases with high-frequency JAK2 mCAs have marked reductions in measured telomere length – suggesting a relationship between telomere biology and myelofibrosis clonal expansion. Our results advance understanding of the germline-somatic interaction at JAK2 and implicate mCAs involving JAK2 as strong promoters of clonal expansion of those mutated clones.

Myelofibrosis is a risk factor for the development of Acute Myeloid Leukaemia. Here, the authors carry out an integrated genomic investigation of 933 myelofibrosis patients, and identified interactions between germline and somatic variation in patients who required haematopoietic cell transplantation.

Genetics and Epigenetics in Neoplasms with Plasmacytoid Dendritic Cells

Simple Summary

Differential diagnosis between Blastic pDC Neoplasm (BPDCN) and Acute Myeloid Leukemia with pDC expansion (pDC-AML) is particularly challenging, and genomic features can help in diagnosis. This review aims at clarifying recent data on genomics features because the past five years have generated a large amount of original data regarding pDC neoplasms. The genetic landscape of BPDCN is now well-defined, with important updates concerning MYC/MYC rearrangements, but also epigenetic defects and novel concepts in oncogenic and immune pathways. Concerning pDC-AML, they now appear to exhibit an original mutation landscape, especially with RUNX1 mutations, which is of interest for diagnostic criteria and for therapeutic purposes. We highlight here these two different profiles, which contribute to differential diagnosis between BPDCN and pDC-AML. This point is particularly important for the study of different therapeutic strategies between BPDCN and AML.

Abstract

Plasmacytoid Dendritic Cells (pDC) are type I interferon (IFN)-producing cells that play a key role in immune responses. Two major types of neoplastic counterparts for pDC are now discriminated: Blastic pDC Neoplasm (BPDCN) and Mature pDC Proliferation (MPDCP), associated with myeloid neoplasm. Two types of MPDCP are now better described: Chronic MyeloMonocytic Leukemia with pDC expansion (pDC-CMML) and Acute Myeloid Leukemia with pDC expansion (pDC-AML). Differential diagnosis between pDC-AML and BPDCN is particularly challenging, and genomic features can help for diagnosis. Here, we systematically review the cytogenetic, molecular, and transcriptional characteristics of BPDCN and pDC-AML. BPDCN are characterized by frequent complex karyotypes with recurrent MYB/MYC rearrangements as well as recurrent deletions involving ETV6, IKZF1, RB1, and TP53 loci. Epigenetic and splicing pathways are also particularly mutated, while original processes are dysregulated, such as NF-kB, TCF4, BCL2, and IFN pathways; neutrophil-specific receptors; and cholinergic signaling. In contrast, cytogenetic abnormalities are limited in pDC-AML and are quite similar to other AML. Interestingly, RUNX1 is the most frequently mutated gene (70% of cases). These typical genomic features are of potential interest for diagnosis, and also from a prognostic or therapeutic perspective.

Case Report: A Case of Myeloproliferative Neoplasm Complicated by Alopecia Areata

Myeloproliferative neoplasms (MPNs) are caused by genetic abnormalities in the stem cells and manifest with various systemic symptoms. Here, we describe a case of MPN complicated by alopecia areata. A 51-year-old woman visited our hematology department for further evaluation of a slight platelet elevation. Her recent medical history included 3 years of concurrent severe alopecia, mild fatigue, and hot flashes but no fever and weight loss. Physical examination revealed unilateral hair loss on the entire body but no hepatosplenomegaly. Laboratory analysis revealed a normal hemoglobin level, normal white blood cell count, and platelet count of 377,000/μL. Genetic testing confirmed the presence of the JAK2 V617F mutation. Bone marrow examination revealed no morphologic dysplasia in any stem cell lineage and no fibrotic change. Skin biopsy revealed lymphocyte infiltration around the hair follicles. We diagnosed MPN, unclassifiable, which was believed to be the cause of alopecia. About 6 months after treatment with ruxolitinib began, the patient's hair growth dramatically improved. The differential diagnosis of MPNs should include hematological diseases when affected patients have alopecia areata.

The Application of NextGen Sequencing in the Diagnosis of Myeloid Neoplasms in Myeloma Patients With Cytopenia

BACKGROUND

Multiple myeloma (MM) is an incurable clonal neoplasm that usually requires long-term treatment, which may result in secondary cytopenia(s) and myeloid neoplasms. We investigated the landscape of mutations detected by NextGen sequencing (NGS) in myeloma patients with cytopenia.

METHODS AND MATERIALS

MM patients (n = 196) with cytopenia(s) and NGS results were identified and divided into 4 groups: 1) patients with myeloma only and no myeloid neoplasms; 2) patients with myeloid neoplasms but no myeloma; 3) patients with concurrent myeloma and myeloid neoplasms; and 4) patients with no myeloma or myelodysplasia.

RESULTS

The most frequently mutated genes were TP53, DNMT3A, TET2, ASXL1, and KRAS. TP53 mutations were predominantly found among patients with myeloid neoplasms with or without concomitant MM. SF3B1 and TET, the genes most commonly mutated in myelodysplastic syndromes, were less frequently identified among MM patients. ASXL1 mutations were more commonly associated with myeloid neoplasms, whereas KRAS and DNMT3A mutations were more closely associated with MM than myeloid neoplasms. RUNX1 mutations showed closer association with myeloid neoplasms. Fifty-eight patients harbored clonal myeloid gene mutations but no overt morphologic or cytogenetic abnormalities, of which 7 patients had myelodysplastic syndromes that was missed by the original pathologists. Thrombocytopenia appeared to be a more reliable marker than anemia or neutropenia to trigger work-up for myeloid neoplasms.

CONCLUSION

NGS could greatly help with diagnosing myeloid neoplasms in MM patients with cytopenia(s). The depicted gene landscape may facilitate our daily interpretation of NextGen sequencing (NGS).

Comprehensive Analysis of Acquired Genetic Variants and Their Prognostic Impact in Systemic Mastocytosis

Systemic mastocytosis (SM) is a rare clonal haematopoietic stem cell disease in which activating KIT mutations (most commonly KIT D816V) are present in virtually every (>90%) adult patient at similar frequencies among non-advanced and advanced forms of SM. The KIT D816V mutation is considered the most common pathogenic driver of SM. Acquisition of this mutation early during haematopoiesis may cause multilineage involvement of haematopoiesis by KIT D816V, which has been associated with higher tumour burden and additional mutations in other genes, leading to an increased rate of transformation to advanced SM. Thus, among other mutations, alterations in around 30 genes that are also frequently mutated in other myeloid neoplasms have been reported in SM cases. From these genes, 12 (i.e., ASXL1, CBL, DNMT3A, EZH2, JAK2, KRAS, NRAS, SF3B1, RUNX1, SF3B1, SRSF2, TET2) have been recurrently reported to be mutated in SM. Because of all the above, assessment of multilineage involvement of haematopoiesis by the KIT D816V mutation, in the setting of multi-mutated haematopoiesis as revealed by a limited panel of genes (i.e., ASXL1, CBL, DNMT3A, EZH2, NRAS, RUNX1 and SRSF2) and associated with a poorer patient outcome, has become of great help to identify SM patients at higher risk of disease progression and/or poor survival who could benefit from closer follow-up and eventually also early cytoreductive treatment.

Mutational landscape of blast phase myeloproliferative neoplasms (MPN-BP) and antecedent MPN

Myeloproliferative neoplasms (MPN) have an inherent tendency to evolve to the blast phase (BP), characterized by ≥20% myeloblasts in the blood or bone marrow. MPN-BP portends a dismal prognosis and currently, effective treatment modalities are scarce, except for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in selected patients, particularly those who achieve complete/partial remission. The mutational landscape of MPN-BP differs from de novo acute myeloid leukemia (AML) in several key aspects, such as significantly lower frequencies of FLT3 and DNMT3A mutations, and higher incidence of IDH1/2 and TP53 in MPN-BP. Herein, we comprehensively review the impact of the three signaling driver mutations (JAK2 V617F, CALR exon 9 indels, MPL W515K/L) that constitutively activate the JAK/STAT pathway, and of the other somatic non-driver mutations (epigenetic, mRNA splicing, transcriptional regulators, and mutations in signal transduction genes) that cooperatively or independently promote MPN progression and leukemic transformation. The MPN subtype, harboring two or more high-molecular risk (HMR) mutations (epigenetic regulators and mRNA splicing factors) and "triple-negative" PMF are among the critical factors that increase risk of leukemic transformation and shorten survival. Primary myelofibrosis (PMF) is the most aggressive MPN; and polycythemia vera (PV) and essential thrombocythemia (ET) are relatively indolent subtypes. In PV and ET, mutations in splicing factor genes are associated with progression to myelofibrosis (MF), and in ET, TP53 mutations predict risk for leukemic transformation. The advent of targeted next-generation sequencing and improved prognostic scoring systems for PMF inform decisions regarding allo-HSCT. The emergence of treatments targeting mutant enzymes (e.g., IDH1/2 inhibitors) or epigenetic pathways (BET and LSD1 inhibitors) along with new insights into the mechanisms of leukemogenesis will hopefully lead the way to superior management strategies and outcomes of MPN-BP patients.

Myelofibrosis: Genetic Characteristics and the Emerging Therapeutic Landscape

Primary myelofibrosis (PMF) is one of three myeloproliferative neoplasms (MPN) that are morphologically and molecularly inter-related, the other two being polycythemia vera (PV) and essential thrombocythemia (ET). MPNs are characterized by JAK-STAT-activating JAK2, CALR, or MPL mutations that give rise to stem cell-derived clonal myeloproliferation, which is prone to leukemic and, in case of PV and ET, fibrotic transformation. Abnormal megakaryocyte proliferation is accompanied by bone marrow fibrosis and characterizes PMF, while the clinical phenotype is pathogenetically linked to ineffective hematopoiesis and aberrant cytokine expression. Among MPN-associated driver mutations, type 1-like CALR mutation has been associated with favorable prognosis in PMF, while ASXL1, SRSF2, U2AF1-Q157, EZH2, CBL, and K/NRAS mutations have been shown to be prognostically detrimental. Such information has enabled development of exclusively genetic (GIPSS) and clinically integrated (MIPSSv2) prognostic models that facilitate individualized treatment decisions. Allogeneic stem cell transplantation remains the only treatment modality in MF with the potential to prolong survival, whereas drug therapy, including JAK2 inhibitors, is directed mostly at the inflammatory component of the disease and is therefore palliative in nature. Similarly, disease-modifying activity remains elusive for currently available investigational drugs, while their additional value in symptom management awaits controlled confirmation. There is a need for genetic characterization of clinical observations followed by in vitro and in vivo preclinical studies that will hopefully identify therapies that target the malignant clone in MF to improve patient outcomes.

Understanding Aberrant Signaling to Elude Therapy Escape Mechanisms in Myeloproliferative Neoplasms

Aberrant signaling in myeloproliferative neoplasms may arise from alterations in genes coding for signal transduction proteins or epigenetic regulators. Both mutated and normal cells cooperate, altering fragile balances in bone marrow niches and fueling persistent inflammation through paracrine or systemic signals. Despite the hopes placed in targeted therapies, myeloid proliferative neoplasms remain incurable diseases in patients not eligible for stem cell transplantation. Due to the emergence of drug resistance, patient management is often very difficult in the long term. Unexpected connections among signal transduction pathways highlighted in neoplastic cells suggest new strategies to overcome neoplastic cell adaptation.

The Role of LNK (SH2B3) in the Regulation of JAK-STAT Signalling in Haematopoiesis

LNK is a member of the SH2B family of adaptor proteins and is a non-redundant regulator of cytokine signalling. Cytokines are secreted intercellular messengers that bind to specific receptors on the surface of target cells to activate the Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signalling pathway. Activation of the JAK-STAT pathway leads to proliferative and often inflammatory effects, and so the amplitude and duration of signalling are tightly controlled. LNK binds phosphotyrosine residues to signalling proteins downstream of cytokines and constrains JAK-STAT signalling. Mutations in LNK have been identified in a range of haematological and inflammatory diseases due to increased signalling following the loss of LNK function. Here, we review the regulation of JAK-STAT signalling via the adaptor protein LNK and discuss the role of LNK in haematological diseases.

Is It Possible to Predict Clonal Thrombocytosis in Triple-Negative Patients with Isolated Thrombocytosis Based Only on Clinical or Blood Findings?

JAK2, MPL, and CALR mutations define clonal thrombocytosis in about 90% of patients with sustained isolated thrombocytosis. In the remainder of patients (triple-negative patients) diagnosing clonal thrombocytosis is especially difficult due to the different underlying conditions and possible inconclusive bone marrow biopsy results. The ability to predict patients with sustained isolated thrombocytosis with a potential clonal origin has a prognostic value and warrants further examination. The aim of our study was to define a non-invasive clinical or blood parameter that could help predict clonal thrombocytosis in triple-negative patients. We studied 237 JAK2 V617-negative patients who were diagnosed with isolated thrombocytosis and referred to the haematology service. Sixteen routine clinical and blood parameters were included in the logistic regression model which was used to predict the type of thrombocytosis (reactive/clonal). Platelet count and lactate dehydrogenase (LDH) were the only statistically significant predictors of clonal thrombocytosis. The platelet count threshold for the most accurate prediction of clonal or reactive thrombocytosis was 449 × 10⁹/L. Other tested clinical and blood parameters were not statistically significant predictors of clonal thrombocytosis. The level of LDH was significantly higher in CALR-positive patients compared to CALR-negative patients. We did not identify any new clinical or blood parameters that could distinguish clonal from reactive thrombocytosis. When diagnosing clonal thrombocytosis triple-negative patients are most likely to be misdiagnosed. Treatment in patients with suspected triple negative clonal thrombocytosis should not be delayed if cardiovascular risk factors or pregnancy coexist, even in the absence of firm diagnostic criteria. In those cases the approach “better treat more than less” should be followed.

Comparative Mutational Profiling of Hematopoietic Progenitor Cells and Circulating Endothelial Cells (CECs) in Patients with Primary Myelofibrosis

A role of endothelial cells (ECs) in Primary Myelofibrosis (PMF) was supposed since JAK2 mutation was found in endothelial precursor cells (EPCs) and in ECs captured by laser microdissection. By Cell Search method, the circulating endothelial cells (CECs) from 14 PMF patients and 5 healthy controls have been isolated and compared by NGS with CD34+Hematopoietic stem and progenitors cells (HSPCs) for panel of 54 myeloid-associated mutations. PMF patients had higher levels of CECs. No mutation was found in HSPCs and CECs from controls, while CECs from PMF patients presented several somatic mutations. 72% of evaluable patients shared at least one mutation between HSPCs and CECs. 2 patients shared the JAK2 mutation, together with ABL1, IDH1, TET2 and ASXL1, KMT2A, respectively. 6 out of 8 shared only NON MPN-driver mutations: TET2 and NOTCH1 in one case; individual paired mutations in TP53, KIT, SRSF2, NOTCH1 and WT1, in the other cases. In conclusion, 70% of PMF patients shared at least one mutation between HSPCs and CECs. These latter harbored several myeloid-associated mutations, besides JAK2V617F mutation. Our results support a primary involvement of EC in PMF and provide a new methodological approach for further studies exploring the role of the “neoplastic” vascular niche.

Philadelphia-Negative MPN: A Molecular Journey, from Hematopoietic Stem Cell to Clinical Features

Philadelphia negative Myeloproliferative Neoplasms (MPN) are a heterogeneous group of hematopoietic stem cell diseases. MPNs show different risk grades of thrombotic complications and acute myeloid leukemia evolution. In the last couple of decades, from JAK2 mutation detection in 2005 to the newer molecular trademarks studied through next generation sequencing, we are learning to approach MPNs from a deeper perspective. Here, we intend to elucidate the important factors affecting MPN clonal advantage and the reasons why some patients progress to more aggressive disease. Understanding these mechanisms is the key to developing new treatment approaches and targeted therapies for MPN patients.

Sequential Development of JAK2V617F Mutation and BCR-ABL1 Fusion in Individual Patients With Myeloproliferative Neoplasms: A Linear Clonal Evolution or Parallel Clonal Competition?

CONTEXT.—

Concomitant BCR-ABL1 and JAK2V617F in myeloproliferative neoplasms (MPNs) is rare, and its pathogenesis and clinical significance are unclear.

OBJECTIVE.—

To investigate the clonal relationship between the 2 genomic alterations, as well as the clinicopathologic impact.

DESIGN.—

Retrospective analysis of MPNs with sequential development of BCR-ABL1 and JAK2V617F.

RESULTS.—

Of 6 cases, 5 had JAK2V617F-positive MPN diagnosed before acquiring BCR-ABL1 years later, and 1 had BCR-ABL1+ chronic myeloid leukemia before JAK2V617F-positive myelofibrosis completely replaced the BCR-ABL1+ clone 1 year after tyrosine kinase inhibitor therapy. Among the former group, treatment for the initial MPN involved hydroxyurea, ruxolitinib, and/or supportive care, and the latency to the development of JAK2V617F ranged from 4 to 13 years (median of 9 years). Four cases showed retention of JAK2V617F, whereas BCR-ABL1 emerged as the major clone, including 2 that exhibited parallel increases in JAK2V617F and BCR-ABL1 burdens, with both genomic markers exceeding 50%. Three patients received stem cell transplants and demonstrated sustained engraftment, with the genomic markers below detectable levels.

CONCLUSIONS.—

Most MPNs with concomitant JAK2V617F and BCR-ABL1 are actually composite MPNs with a "second hit" residing on a different clone. Rare cases demonstrate a subclone harboring a "double-hit" in a background of a JAK2V617F-positive stem line clone. The probability of a "double-hit" with a BCR-ABL1+ stem line clone is probably reduced by effective tyrosine kinase inhibitor treatment. The treatment often involves combined kinase inhibitors and/or hydroxyurea, but the outcome is unpredictable; hematopoietic stem cell transplantation may be the ultimate therapeutic option for this complicated disease.

CBL aggravates Ang II-induced cardiac hypertrophy via the VHL/HIF-1α pathway

CBL (Casitas B cell lymphoma), an important ubiquitin protein ligase, is involved in protein folding, protein maturation, and proteasome-dependent protein catabolism in different cells. However, its role in cardiac hypertrophy is still unclear. In this study, we found that expression of CBL is increased in an Ang II-induced mouse cardiac hypertrophy animal model and in Ang II-treated H9C2 cells. Interference with CBL expression attenuates the degree of myocardial hypertrophy as well as the expression of hypertrophy-related genes in H9C2 cells. Further research found that CBL aggravates myocardial hypertrophy by activating HIF-1α, which is an aggravating factor for hypertrophy. The effect of CBL on promoting myocardial hypertrophy was reversed by interference with HIF-1α. Mechanistically, we found that CBL directly interacted with and degraded VHL by increasing its ubiquitination level, which is a widely accepted regulatory factor of HIF-1α. Finally, our results showed that CBL was partially dependent on degradation of VHL and that activation of HIF-1α promoted myocardial hypertrophy. Collectively, these findings suggest that strategies based on activation of the CBL/HIF-1α axis might be promising for the treatment of hypertrophic cardiomyopathy.

Early and late stage MPN patients show distinct gene expression profiles in CD34+ cells

Myeloproliferative neoplasms (MPN), comprising essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF), are hematological disorders of the myeloid lineage characterized by hyperproliferation of mature blood cells. The prediction of the clinical course and progression remains difficult and new therapeutic modalities are required. We conducted a CD34⁺ gene expression study to identify signatures and potential biomarkers in the different MPN subtypes with the aim to improve treatment and prevent the transformation from the rather benign chronic state to a more malignant aggressive state. We report here on a systematic gene expression analysis (GEA) of CD34⁺ peripheral blood or bone marrow cells derived from 30 patients with MPN including all subtypes (ET (n = 6), PV (n = 11), PMF (n = 9), secondary MF (SMF; post-ET-/post-PV-MF; n = 4)) and six healthy donors. GEA revealed a variety of differentially regulated genes in the different MPN subtypes vs. controls, with a higher number in PMF/SMF (200/272 genes) than in ET/PV (132/121). PROGENγ analysis revealed significant induction of TNFα/NF-κB signaling (particularly in SMF) and reduction of estrogen signaling (PMF and SMF). Consistently, inflammatory GO terms were enriched in PMF/SMF, whereas RNA splicing–associated biological processes were downregulated in PMF. Differentially regulated genes that might be utilized as diagnostic/prognostic markers were identified, such as AREG, CYBB, DNTT, TIMD4, VCAM1, and S100 family members (S100A4/8/9/10/12). Additionally, 98 genes (including CLEC1B, CMTM5, CXCL8, DACH1, and RADX) were deregulated solely in SMF and may be used to predict progression from early to late stage MPN.

Bleeding diathesis in mice lacking JAK2 in platelets

The tyrosine kinase JAK2 is a critical component of intracellular JAK/STAT cytokine signaling cascades that is prevalent in hematopoietic cells, such as hematopoietic stem cells and megakaryocytes (MKs). Individuals expressing the somatic JAK2 V617F mutation commonly develop myeloproliferative neoplasms (MPNs) associated with venous and arterial thrombosis, a leading cause of mortality. The role of JAK2 in hemostasis remains unclear. We investigated the role of JAK2 in platelet hemostatic function using Jak2fl/fl Pf4-Cre (Jak2Plt-/-) mice lacking JAK2 in platelets and MKs. Jak2Plt-/- mice developed MK hyperplasia and splenomegaly associated with severe thrombocytosis and bleeding. This notion was supported by failure to occlude in a ferric chloride carotid artery injury model and by a cremaster muscle laser-induced injury assay, in which Jak2Plt-/- platelets failed to form stable thrombi. Jak2Plt-/- platelets formed thrombi poorly after adhesion to type 1 collagen under arterial shear rates. Jak2Plt-/- platelets spread poorly on collagen under static conditions or on fibrinogen in response to the collagen receptor GPVI-specific agonist, collagen-related peptide (CRP). After activation with collagen, CRP, or the CLEC-2 agonist rhodocytin, Jak2Plt-/- platelets displayed decreased α-granule secretion and integrin αIIbβ3 activation or aggregation, but showed normal responses to thrombin. Jak2Plt-/- platelets had impaired intracellular signaling when activated via GPVI, as assessed by tyrosine phosphorylation. Together, the results show that JAK2 deletion impairs platelet immunoreceptor tyrosine-based activation motif signaling and hemostatic function in mice and suggest that aberrant JAK2 signaling in patients with MPNs affects GPVI signaling, leading to hemostatic platelet function.

Combined Ruxolitinib and Venetoclax Treatment in a Patient with a BCR-JAK2 Rearranged Myeloid Neoplasm

Hematological malignancies with a BCR-JAK2 rearrangement have been described only sporadically in the literature over the last three decades. Although most patients suffer from a chronic myeloid neoplasm with marked eosinophilia, the clinical presentation varies significantly and can even manifest as a lymphoid malignancy. In this case report, we present a patient with a therapy-related BCR-JAK2⁺ myeloid neoplasm with extensive extramedullary disease localizing in the lymph nodes. While treatment with a JAK2 inhibitor (ruxolitinib) was not able to stop disease progression, combination treatment with inhibitors of both JAK2 and BCL2 (venetoclax) resulted in disease control for over 1.5 years. Combining these two inhibitors might be strategic in these patients, not only because BCL2 is a downstream target of JAK/STAT signaling but also because BCL2 is crucial for JAK2 inhibitor resistance. The recent inclusion of JAK2-rearranged malignancies in major classification systems and guidelines emphasizes the importance of not only getting a better understanding of the clinical phenotype of these rare disorders but also of identifying alternative treatment options for patients ineligible for allogeneic stem cell transplantation. Considering the low toxicity of combination treatment with these two small molecule inhibitors, this regimen could be further explored in future studies.

Isolated ten-eleven translocation 2 positive in triple negative essential thrombocythemia: Case report and literature review

Essential thrombocythemia is one of the famous diseases under the category of myeloproliferative disorder. It is an end result of a genetic mutation of one or more of the most frequent oncogenes such as Janos kinase 2 (JAK2), MPL proto-oncogene, thrombopoietin receptor (MPL), and calreticulin (CALR). However, negative genetic markers, so-called (triple negative disease), can happen in the presence of other uncommon types of mutation. TET2 (ten-eleven translocation 2) positive as isolated genetic marker in triple negative essential thrombocythemia is uncommon genetic presentation. For that, we are reporting a 22-year-old lady who presented with a feature of dyspepsia and accidentally found to have persistently high platelet count, even after treating her mild iron deficiency anemia with no other secondary causes. Further investigations and bone marrow biopsy supported the diagnosis of isolated TET2 positive in triple negative essential thrombocythemia. We treated her conservatively with good hydration and low dose of aspirin. In conclusion, isolated TET2 positive in triple negative essential thrombocythemia at presentation is uncommon with no clear management or risk stratification guideline. However, it is hypothesized that TET2 mutation precedes JAK2; therefore, the detection of isolated TET2 in a triple negative essential thrombocythemia case should be closely followed for clonal evolution in long term. Further study and guidelines required in this area.

Synoptic Diagnostics of Myeloproliferative Neoplasms: Morphology and Molecular Genetics

Simple Summary

The diagnosis of myeloproliferative neoplasms requires assessment of a combination of clinical, morphological, immunophenotypic and genetic features, and this integrated, multimodal approach forms the basis for precise classification. Evaluation includes cell counts and morphology in the peripheral blood, bone marrow aspiration and trephine biopsy, and may encompass flow cytometry for specific questions. Diagnosis nowadays is completed by targeted molecular analysis for the detection of recurrent driver and, optionally, disease-modifying mutations. According to the current World Health Organization classification, all myeloproliferative disorders require assessment of molecular features to support the diagnosis or confirm a molecularly defined entity. This requires a structured molecular analysis workflow tailored for a rapid and cost-effective diagnosis. The review focuses on the morphological and molecular features of Ph-negative myeloproliferative neoplasms and their differential diagnoses, addresses open questions of classification, and emphasizes the enduring role of histopathological assessment in the molecular era.

Abstract

The diagnosis of a myeloid neoplasm relies on a combination of clinical, morphological, immunophenotypic and genetic features, and an integrated, multimodality approach is needed for precise classification. The basic diagnostics of myeloid neoplasms still rely on cell counts and morphology of peripheral blood and bone marrow aspirate, flow cytometry, cytogenetics and bone marrow trephine biopsy, but particularly in the setting of Ph− myeloproliferative neoplasms (MPN), the trephine biopsy has a crucial role. Nowadays, molecular studies are of great importance in confirming or refining a diagnosis and providing prognostic information. All myeloid neoplasms of chronic evolution included in this review, nowadays feature the presence or absence of specific genetic markers in their diagnostic criteria according to the current WHO classification, underlining the importance of molecular studies. Crucial differential diagnoses of Ph− MPN are the category of myeloid/lymphoid neoplasms with eosinophilia and gene rearrangement of PDGFRA, PDGFRB or FGFR1, or with PCM1-JAK2, and myelodysplastic/myeloproliferative neoplasms (MDS/MPN). This review focuses on morphological, immunophenotypical and molecular features of BCR-ABL1-negative MPN and their differential diagnoses. Furthermore, areas of difficulties and open questions in their classification are addressed, and the persistent role of morphology in the area of molecular medicine is discussed.

Identification of Potential Key Genes and Regulatory Markers in Essential Thrombocythemia Through Integrated Bioinformatics Analysis and Clinical Validation

Introduction

Essential thrombocytosis (ET) is a group of myeloproliferative neoplasms characterized by abnormal proliferation of platelet and megakaryocytes. Research on potential key genes and novel regulatory markers in essential thrombocythemia (ET) is still limited.

Methods

Downloading array profiles from the Gene Expression Omnibus database, we identified the differentially expressed genes (DEGs) through comprehensive bioinformatic analysis. GO, and REACTOME pathway enrichment analysis was used to predict the potential functions of DEGs. Besides, constructing a protein–protein interaction (PPI) network through the STRING database, we validated the expression level of hub genes in an independent cohort of ET, and the transcription factors (TFs) were detected in the regulatory networks of TFs and DEGs. And the candidate drugs that are targeting hub genes were identified using the DGIdb database.

Results

We identified 63 overlap DEGs that included 21 common up-regulated and 42 common down-regulated genes from two datasets. Functional enrichment analysis shows that the DEGs are mainly enriched in the immune system and inflammatory processes. Through PPI network analysis, ACTB, PTPRC, ACTR2, FYB, STAT1, ETS1, IL7R, IKZF1, FGL2, and CTSS were selected as hub genes. Interestingly, we found that the dysregulated hub genes are also aberrantly expressed in a bone marrow cohort of ET. Moreover, we found that the expression of CTSS, FGL2, IKZF1, STAT1, FYB, ACTR2, PTPRC, and ACTB genes were significantly under-expressed in ET (P<0.05), which is consistent with our bioinformatics analysis. The ROC curve analysis also shows that these hub genes have good diagnostic value. Besides, we identified 4 TFs (SPI1, IRF4, SRF, and AR) as master transcriptional regulators that were associated with regulating the DEGs in ET. Cyclophosphamide, prednisone, fluorouracil, ruxolitinib, and lenalidomide were predicted as potential candidate drugs for the treatment of ET.

Discussion

These dysregulated genes and predicted key regulators had a significant relationship with the occurrence of ET with affecting the immune system and inflammation of the processes. Some of the immunomodulatory drugs have potential value by targeting ACTB, PTPRC, IL7R, and IKZF1 genes in the treatment of ET.

Molecular pathogenesis of the myeloproliferative neoplasms

The Philadelphia negative myeloproliferative neoplasms (MPN) compromise a heterogeneous group of clonal myeloid stem cell disorders comprising polycythaemia vera, essential thrombocythaemia and primary myelofibrosis. Despite distinct clinical entities, these disorders are linked by morphological similarities and propensity to thrombotic complications and leukaemic transformation. Current therapeutic options are limited in disease-modifying activity with a focus on the prevention of thrombus formation. Constitutive activation of the JAK/STAT signalling pathway is a hallmark of pathogenesis across the disease spectrum with driving mutations in JAK2, CALR and MPL identified in the majority of patients. Co-occurring somatic mutations in genes associated with epigenetic regulation, transcriptional control and splicing of RNA are variably but recurrently identified across the MPN disease spectrum, whilst epigenetic contributors to disease are increasingly recognised. The prognostic implications of one MPN diagnosis may significantly limit life expectancy, whilst another may have limited impact depending on the disease phenotype, genotype and other external factors. The genetic and clinical similarities and differences in these disorders have provided a unique opportunity to understand the relative contributions to MPN, myeloid and cancer biology generally from specific genetic and epigenetic changes. This review provides a comprehensive overview of the molecular pathophysiology of MPN exploring the role of driver mutations, co-occurring mutations, dysregulation of intrinsic cell signalling, epigenetic regulation and genetic predisposing factors highlighting important areas for future consideration.

Quantification of JAK2V617F mutation load by droplet digital PCR can aid in diagnosis of myeloproliferative neoplasms

INTRODUCTION

This study developed a method for quantifying the JAK2V617F mutation load in patients with myeloproliferative neoplasm (MPN) using droplet digital PCR (ddPCR), which provides a new laboratory method for diagnosing polycythemia vera (PV), essential thrombocythemia (ET), and pre-primary myelofibrosis (pre-PMF).

METHODS

Patients with MPN who had JAK2V617F mutations from March 2013 to August 2019 were enrolled in this study. JAK2V617F mutation loads were quantified using ddPCR technology.

RESULTS

The study examined 225 patients, including 135 with ET, 58 with PV, and 32 with PMF. JAK2V617F mutation loads significantly differed (P < .001) between the ET and PV groups and between the ET and PMF groups. Bone marrow biopsies were reclassified in accordance with the 2016 World Health Organization diagnostic criteria, which revealed 132 patients with MPN: 62 with ET, 35 with PV, 17 with pre-PMF, and 18 with overt-PMF. JAK2V617F mutation loads significantly differed (P < .001) between the ET and PV groups and between the ET and pre-PMF groups. The cutoff value between the ET and pre-PMF groups was 49.9.

CONCLUSION

JAK2V617F mutation loads provide an additional basis for diagnosis of ET, PV, and PMF, particularly regarding differentiation between ET and pre-PMF.

Important Pathologic Considerations for Establishing the Diagnosis of Myelofibrosis

Diagnostic criteria for primary myelofibrosis as defined by the 2017 revised World Health Organization (WHO) classification system incorporate clinical and laboratory findings, including driver mutational status (JAK2, MPL, CALR. and triple negative). The WHO emphasized the role of histopathology in making an accurate diagnosis of primary myelofibrosis and successfully incorporated a fibrosis scoring system and scoring schemas for collagen fibrosis and osteosclerosis. These steps represent a significant addition to the standardization of myelofibrosis evaluation and minimize the risk for misdiagnosis. This article reviews important pathologic considerations along with highlights of potentially relevant pitfalls relevant to histopathological diagnosis of myelofibrosis.

Gene expression profiling of CD34(+) cells from patients with myeloproliferative neoplasms

Myeloproliferative neoplasms (MPN) are clonal disorders characterized by the increased proliferation of hematopoietic stem cell precursors and mature blood cells. Mutations of Janus kinase 2 (JAK2), Calreticulin (CALR) and MPL (myeloproliferative leukemia virus) are key driver mutations in MPN. However, the molecular profile of triple negative MPN has been a subject of ambiguity over the past few years. Mutations of, methylcytosine dioxygenase TET2, polycomb group protein ASXL1 and histone-lysine N-methyltransferase EZH2 genes have accounted for certain subsets of triple negative MPNs but the driving cause for majority of cases is still unexplored. The present study performed a microarray-based transcriptomic profile analysis of bone marrow-derived CD34(+) cells from seven MPN samples. A total of 21,448 gene signatures were obtained, which were further filtered into 472 upregulated and 202 downregulated genes. Gene ontology and protein-protein interaction (PPI) network analysis highlighted an upregulation of genes involved in cell cycle and chromatin modification in JAK2V617F negative vs. positive MPN samples. Out of the upregulated genes, seven were associated with the hematopoietic stem cell signature, while forty-seven were associated with the embryonic stem cell signature. The majority of the genes identified were under the control of NANOG and E2F4 transcription factors. The PPI network indicated a strong interaction between chromatin modifiers and cell cycle genes, such as histone-lysine N-methyltransferase SUV39H1, SWI/SNF complex subunit SMARCC2, SMARCE2, chromatin remodeling complex subunit SS18, tubulin β (TUBB) and cyclin dependent kinase CDK1. Among the upregulated epigenetic markers, there was a ~10-fold increase in MYB expression in JAK2V617F negative samples. A significant increase in total CD34 counts in JAK2V617F negative vs. positive samples (P<0.05) was also observed. Overall, the present data showed a distinct pattern of expression in JAK2V617F negative vs. positive samples with upregulated genes involved in epigenetic modification.

The Essential Thrombocythemia in 2020: What We Know and Where We Still Have to Dig Deep

The Essential Thrombocythemia is a Chronic Philadelphia-negative Myeloproliferative Neoplasm characterized by a survival curve that is only slightly worse than that of age- and sex-adjusted healthy population. The criteria for diagnosis were reviewed in 2016 by WHO. The incidence varies from 0.2 to 2.5:100 000 people per year, with a prevalence of 38 to 57 cases per 100 000 people. The main characteristics of ET are the marked thrombocytosis and the high frequency of thrombosis. The spectrum of symptoms is quite wide, but fatigue results to be the most frequent. Thrombosis is frequently observed, often occurring before or at the time of diagnosis. The classification of thrombotic risk has undergone several revisions. Recently, the revised-IPSET-t has distinguished 4 risk classes, from very low risk to high risk. Driver mutations seem to influence thrombotic risk and prognosis, while the role of sub-driver mutations still remains uncertain. Antiplatelet therapy is recommended in all patients aged ⩾ 60 years and in those with a positive history of thrombosis or with cardiovascular risk factors, while cytoreductive therapy with hydroxyurea or interferon is reserved for high-risk patients.

Prevalence of definite antiphospholipid syndrome in carriers of the JAK2V617F mutation

INTRODUCTION

Patients with Philadelphia-negative myeloproliferative neoplasms (MPNs), particularly those carrying the JAK2^V617F mutation, are at increased risk of thrombosis. While an association of MPNs with autoimmune disorders has been established, the prevalence of inherited or acquired thrombophilias in JAK2^V617F-positive patients remains obscure. We therefore investigated the coincidence of the JAK2^V617F mutation with additional thrombogenic risk factors.

METHODS

In a retrospective study, we analyzed all patients referred for thrombophilia work-up between 01/2011 and 08/2019, in whom additional JAK2^V617F mutation analysis was performed because of thromboembolic events that were recurrent, atypically located and/or associated with abnormal blood counts.

RESULTS

Of 472 tested patients, 49 (10.4%) were JAK2^V617F-positive. While the frequency of inherited thrombophilias (factor V Leiden and prothrombin G20210A mutation, deficiency of antithrombin, protein C, protein S) was not different between the two groups, the prevalence of definite antiphospholipid syndrome (APS), mostly associated with a moderate- or high-risk antibody profile, was significantly higher in patients with (22.4%) than in those without (8.4%) JAK2^V617F mutation (p < 0.01). All evaluable JAK2^V617F-positive patients with APS were subsequently diagnosed with MPN. In patients with JAK2^V617F mutation, presence of concomitant APS was associated with a significantly younger age (49 ± 14 vs. 60 ± 15 years) at the time of thrombophilia work-up (p < 0.05).

CONCLUSION

We found a significant association between JAK2^V617F-positive MPN and definite APS. The presence of concomitant APS in patients carrying the JAK2^V617F mutation may lead to earlier manifestation of thromboembolic events and may warrant more aggressive antithrombotic treatment strategies to prevent recurrence.

Co-existence of mutations in myeloproliferative neoplasms and their clinical significance: a prognostic approach

OBJECTIVE

Myeloproliferative neoplasms (MPNs) are a group of clonal hematopoietic stem cell disorders that may occur after one or more mutations in hematopoietic progenitor cells. In this study, we will review the co-existence of mutations (especially dual mutations) in MPNs and its effect on the prognosis of patients.

METHODS

To find relevant published papers, we systematically searched six major international indexing databases, namely PubMed/Medline, EmBase, Cochrane central, ISI web of science, and Scopus from Feb. 2000 until Jan. 2020. We included the following keywords in the analyzes: Myeloproliferative Disorders, Mutation, Co-existence of Mutations, Acute myeloid leukemia.

RESULTS

Co-existence of several mutations in MPNs is mainly associated with a poor prognosis compared with the unimutated MPN disorders. There are several effective factors such as sequence of mutations, incidence of mutations in one cell or different cells, mutation, and MPN type.

CONCLUSION AND EXPERT COMMENTARY

It seems that monitoring the status of mutations in MPNs and recognizing the co-existence of mutations (especially dual mutations) in order to determine prognosis and possibility of progression to acute form of leukemia can lead to the prediction of prognosis in MPN patients as well as establishment of better and more reliable therapeutic strategies for patients.

The Hidden Pathogenesis of CML: Is BCR-ABL1 the First Event?

PURPOSE OF REVIEW

Identification of the BCR-ABL1 fusion oncogene in patients diagnosed with chronic myeloid leukemia (CML) led to the development of targeted therapy responsible for the dramatic survival benefits observed in the past two decades. However, despite these revolutionary findings, there remains marked disparity in patient outcomes. Why do some patients present de novo while others evolve to the more aggressive stages of CML? Why can select patients successfully discontinue therapy as part of a treatment-free remission attempt whereas others fail to meet specific molecular milestones?

RECENT FINDINGS

BCR-ABL1 kinase mutations are only identified in approximately 50% of patients with poor responses and disease progression, suggesting the presence of alternative resistance mechanisms. Numerous institutions have identified the presence of additional genomic events in addition to BCR-ABL1 with the increasing availability of next-generation sequencing. We explore the potential pathways and events that may cooperate with BCR-ABL1 to answer these questions but also challenge the fundamental tenet that BCR-ABL1 is always the sole event initiating CML.

Patients with Essential Thrombocythemia may be Poor Responders to Enteric-Coated Aspirin, but not to Plain Aspirin

Essential thrombocythemia (ET) patients are treated with aspirin (acetylsalicylic acid [ASA]) to prevent thrombosis. Previous studies showed that serum thromboxane (Tx) B₂ was high 24 hours after enteric-coated (EC)-ASA in ET patients, due to increased number of noninhibited reticulated platelets (RPs), consequent to high platelet turnover, and that ASA should be given twice a day to ET patients. We studied ET patients (n = 17) and healthy subjects (n = 10) on 100 mg EC-ASA once daily; experiments were repeated after 14-day treatment with 100 mg plain-ASA once daily. Serum TxB₂, plasma ASA, and salicylic acid (SA) were measured before the morning dose and up to 8 hours thereafter. Blood activity of ASA-deacethylating esterases, in vitro inhibition of collagen-induced TxB₂ production by ASA (10-1,000 µM), and number of RP were measured. TxB₂ inhibition by ASA in vitro and esterases activities were normal in all subjects. EC-ASA elicited highly variable responses; 6 ET patients were poor responders, as their serum TxB₂ was high after EC-ASA; their plasma levels of ASA and SA were low/undetectable. In contrast to EC-ASA, plain ASA decreased serum TxB₂ and increased plasma ASA and SA in all subjects. Serum TxB₂ was high in ET patients at 24 hours and significantly correlated with RP count (but not RP percentage) and platelet count. Plain ASA should be used in ET patients to inhibit platelets efficiently. The identification of ET patients who might benefit from twice a day ASA could simply be based on their platelet count: since their platelet turnover is not increased, ET patients with normalized platelet count should not need twice a day ASA treatment.