The authors identified calreticulin mutations in the majority of patients with essential thrombocythemia and myelofibrosis who did not have
JAK2
mutations. The mutation alters calreticulin protein, ...and cells expressing the mutant protein are more responsive to growth factors.
Philadelphia chromosome–negative myeloproliferative neoplasms include polycythemia vera, essential thrombocythemia, and primary myelofibrosis.
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A unique gain-of-function mutation in the Janus kinase 2 gene (
JAK2
) is found in about three quarters of patients in whom these disease entities have been diagnosed.
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,
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The valine-to-phenylalanine (V617F) alteration constitutively activates JAK2, resulting in increased phosphorylation of its substrates and leading to increased cytokine responsiveness of myeloid cells. The
JAK2
V617F mutation is present in approximately 95% of patients with polycythemia vera and in 50 to 60% of those with essential thrombocythemia or primary myelofibrosis.
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In addition, somatic mutations of
JAK2
exon 12 . . .
The new edition of the 2016 World Health Organization (WHO) classification system for tumors of the hematopoietic and lymphoid tissues was published in September 2017. Under the category of ...myeloproliferative neoplasms (MPNs), the revised document includes seven subcategories: chronic myeloid leukemia, chronic neutrophilic leukemia, polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET), chronic eosinophilic leukemia-not otherwise specified and MPN, unclassifiable (MPN-U); of note, mastocytosis is no longer classified under the MPN category. In the current review, we focus on the diagnostic criteria for JAK2/CALR/MPL mutation-related MPNs: PV, ET, and PMF. In this regard, the 2016 changes were aimed at facilitating the distinction between masked PV and JAK2-mutated ET and between prefibrotic/early and overtly fibrotic PMF. In the current communication, we (i) provide practically useful resource tables and graphs on the new diagnostic criteria including outcome, (ii) elaborate on the rationale for the 2016 changes, (iii) discuss the complementary role of mutation screening, (iv) address ongoing controversies and propose solutions, (v) attend to the challenges of applying WHO criteria in routine clinical practice, and (vi) outline future directions from the perspectives of the clinical pathologist.
Essential thrombocythemia (ET) and primary myelofibrosis (PMF) are chronic diseases characterized by clonal hematopoiesis and hyperproliferation of terminally differentiated myeloid cells. The ...disease is driven by somatic mutations in exon 9 of CALR or exon 10 of MPL or JAK2-V617F in >90% of the cases, whereas the remaining cases are termed “triple negative.” We aimed to identify the disease-causing mutations in the triple-negative cases of ET and PMF by applying whole-exome sequencing (WES) on paired tumor and control samples from 8 patients. We found evidence of clonal hematopoiesis in 5 of 8 studied cases based on clonality analysis and presence of somatic genetic aberrations. WES identified somatic mutations in 3 of 8 cases. We did not detect any novel recurrent somatic mutations. In 3 patients with clonal hematopoiesis analyzed by WES, we identified a somatic MPL-S204P, a germline MPL-V285E mutation, and a germline JAK2-G571S variant. We performed Sanger sequencing of the entire coding region of MPL in 62, and of JAK2 in 49 additional triple-negative cases of ET or PMF. New somatic (T119I, S204F, E230G, Y591D) and 1 germline (R321W) MPL mutation were detected. All of the identified MPL mutations were gain-of-function when analyzed in functional assays. JAK2 variants were identified in 5 of 57 triple-negative cases analyzed by WES and Sanger sequencing combined. We could demonstrate that JAK2-V625F and JAK2-F556V are gain-of-function mutations. Our results suggest that triple-negative cases of ET and PMF do not represent a homogenous disease entity. Cases with polyclonal hematopoiesis might represent hereditary disorders.
•Activating mutations outside exon 10 of MPL were identified in 10% (7 of 69) of triple-negative cases of ET and PMF.•JAK2-V625F and JAK2-F556V were identified in 2 triple-negative cases of ET and were shown to activate JAK-STAT5 signaling.
Patients with myelofibrosis who were treated with ruxolitinib, a JAK1 and JAK2 inhibitor, showed significant responses with respect to spleen size and quality of life. No effect on overall survival ...was seen, but one third of the patients assigned to the best available therapy could not be evaluated.
Myelofibrosis, which can present as a primary disease or can evolve from polycythemia vera or essential thrombocythemia,
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is characterized by marrow fibrosis, progressive anemia, and extramedullary hematopoiesis, manifested primarily as splenomegaly. Severe constitutional symptoms (e.g., night sweats and weight loss), pruritus, fatigue, and sequelae of splenomegaly are common.
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The median survival from the time of diagnosis is 4 years for patients with intermediate-2–risk disease and 2 years for patients with high-risk disease.
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Apart from allogeneic stem-cell transplantation, treatment is palliative and does not address the characteristic abnormality identified in myelofibrosis, a dysregulation of Janus kinase (JAK)–mediated cytokine and growth-factor signal . . .
Genome-wide association studies have identified a number of new disease susceptibility loci that represent haplotypes defined by numerous SNPs. SNPs within a disease-associated haplotype are thought ...to influence either the expression of genes or the sequence of the proteins they encode. In a series of investigations of the JAK2 gene in myeloproliferative neoplasms, we uncovered a new property of haplotypes that can explain their disease association. We observed a nonrandom distribution of the somatic JAK2V617F oncogenic mutation between two parental alleles of the JAK2 gene. We identified a haplotype that preferentially acquires JAK2V617F and confers susceptibility to myeloproliferative neoplasms. One interpretation of our results is that a certain combination of SNPs may render haplotypes differentially susceptible to somatic mutagenesis. Thus, disease susceptibility loci may harbor somatic mutations that have a role in disease pathogenesis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Accurate prediction of thrombosis in essential thrombocythemia (ET) provides the platform for prospective studies exploring preventive measures. Current risk stratification for thrombosis in ET is ...2-tiered and considers low- and high-risk categories based on the respective absence or presence of either age > 60 years or history of thrombosis. In an international study of 891 patients with World Health Organization (WHO)–defined ET, we identified additional independent risk factors including cardiovascular risk factors and JAK2V617F. Accordingly, we assigned risk scores based on multivariable analysis–derived hazard ratios (HRs) to age > 60 years (HR = 1.5; 1 point), thrombosis history (HR = 1.9; 2 points), cardiovascular risk factors (HR = 1.6; 1 point), and JAK2V617F (HR = 2.0; 2 points) and subsequently devised a 3-tiered prognostic model (low-risk = < 2 points; intermediate-risk = 2 points; and high-risk = > 2 points) using a training set of 535 patients and validated the results in the remaining cohort (n = 356; internal validation set) and in an external validation set (n = 329). Considering all 3 cohorts (n = 1220), the 3-tiered new prognostic model (low-risk n = 474 vs intermediate-risk n = 471 vs high-risk n = 275), with a respective thrombosis risk of 1.03% of patients/y versus 2.35% of patients/y versus 3.56% of patients/y, outperformed the 2-tiered (low-risk 0.95% of patients/y vs high-risk 2.86% of patients/y) conventional risk stratification in predicting future vascular events.
Ph-negative myeloproliferative neoplasms (MPNs) are hematological cancers that can be subdivided into entities with distinct clinical features. Somatic mutations in JAK2, CALR, and MPL have been ...described as drivers of the disease, together with a variable landscape of nondriver mutations. Despite detailed knowledge of disease mechanisms, targeted therapies effective enough to eliminate MPN cells are still missing. In this study of 113 MPN patients, we aimed to comprehensively characterize the mutational landscape of the granulocyte transcriptome using RNA sequencing data and subsequently examine the applicability of immunotherapeutic strategies for MPN patients. Following implementation of customized workflows and data filtering, we identified a total of 13 (12/13 novel) gene fusions, 231 nonsynonymous single nucleotide variants, and 21 insertions and deletions in 106 of 113 patients. We found a high frequency of SF3B1-mutated primary myelofibrosis patients (14%) with distinct 3′ splicing patterns, many of these with a protein-altering potential. Finally, from all mutations detected, we generated a virtual peptide library and used NetMHC to predict 149 unique neoantigens in 62% of MPN patients. Peptides from CALR and MPL mutations provide a rich source of neoantigens as a result of their unique ability to bind many common MHC class I molecules. Finally, we propose that mutations derived from splicing defects present in SF3B1-mutated patients may offer an unexplored neoantigen repertoire in MPNs. We validated 35 predicted peptides to be strong MHC class I binders through direct binding of predicted peptides to MHC proteins in vitro. Our results may serve as a resource for personalized vaccine or adoptive cell–based therapy development.
•Driver mutations in CALR or MPL encode for predicted neoantigens that bind MHC class I with high affinity in MPN patients.•The majority of MPN patients show evidence of recurrent candidate neoantigens, suggesting a potential use for targeted immunotherapy.
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Patients treated with an induction regimen of melphalan, prednisone, and lenalidomide followed by lenalidomide maintenance therapy had longer progression-free survival than those who did not receive ...maintenance therapy.
Melphalan–prednisone (MP) has long been the treatment of choice for patients with multiple myeloma who are older than 65 years of age.
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The introduction of new agents in the past few years has substantially changed the treatment of multiple myeloma. MP plus either thalidomide or bortezomib is reported to improve progression-free survival and overall survival, as compared with MP alone,
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,
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and these combinations are now considered the new standards of care for elderly patients with newly diagnosed multiple myeloma who are ineligible for stem-cell transplantation.
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Lenalidomide in combination with dexamethasone is effective in relapsed or refractory multiple myeloma
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– . . .
The current document is a revision of the International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) criteria for treatment response in myelofibrosis (MF) and ...represents a collaborative effort by the IWG-MRT and the European LeukemiaNet to objectively assess the value of new drugs in inducing morphologic remission or improvement in MF-associated symptomatic burden (MF-SB). Some of the changes in the current revision include stricter definitions of red cell transfusion dependency and independency and consideration of the Myeloproliferative Neoplasm Symptom Assessment Form as a tool to quantify meaningful changes in disease-related symptoms. Six response categories are listed: complete remission (CR) and partial remission signify treatment effects that are consistent with disease modification, whereas drug-induced improvements in MF-SB were annotated as clinical improvement, anemia response, spleen response, or symptoms response. Additional criteria are provided for progressive disease, stable disease, and relapse. The document also includes recommendations for assessing cytogenetic and molecular remissions, without mandating their inclusion for CR assignment.
•Treatment response criteria for MF must capture drug benefit in terms of symptom burden.•The current document includes stricter definitions of red cell transfusion need and independence.
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