Coexistence of JAK2 and BCR-ABL mutation in patient with myeloproliferative neoplasm

From primary myelofibrosis to chronic myeloid leukemia, BCR::ABL1+ B-Lymphoblastic leukemia, and back to primary myelofibrosis: An illustration of dynamic clonal evolution

The simultaneous detection of BCR::ABL1 and JAK2 V617F was rarely reported and their clonal relationship and dynamic clonal shift were not characterized. Here, we described a unique case with the initial presentation as JAK2 V617F+ primary myelofibrosis, followed by the emergence of BCR::ABL1+ chronic myeloid leukemia. The patient then developed BCR::ABL1+ B-lymphoblastic leukemia. Treatment for B-lymphoblastic leukemia prompted a regression to the state of primary myelofibrosis. In light of these observations, we proposed a clonal evolution model for this case.

Is very high platelet count always associated with essential thrombocythemia? An unusual presentation in a child

Myeloproliferative neoplasms are rare in childhood. They are categorized as Philadelphia chromosome-positive and Philadelphia chromosome-negative. Chronic myeloid leukemia (CML) is the most common myeloproliferative disease in which the Philadelphia chromosome is detected as a result of BCR-ABL rearrangements. In others, the most common genetic abnormality is JAK2V617F mutation. The coexistence of these 2 abnormalities in CML is unexpected, and rare cases have recently been reported in adults. We present a child who had a very high platelet count in which we found this coexistence. The clinical presentation, laboratory findings, management, and prognosis of this coexistence is challenging in such a rare condition.

Cytological Diagnosis of Classic Myeloproliferative Neoplasms at the Age of Molecular Biology

Myeloproliferative neoplasms (MPN) are clonal hematopoietic stem cell-derived disorders characterized by uncontrolled proliferation of differentiated myeloid cells. Two main groups of MPN, BCR::ABL1-positive (Chronic Myeloid Leukemia) and BCR::ABL1-negative (Polycythemia Vera, Essential Thrombocytosis, Primary Myelofibrosis) are distinguished. For many years, cytomorphologic and histologic features were the only proof of MPN and attempted to distinguish the different entities of the subgroup BCR::ABL1-negative MPN. World Health Organization (WHO) classification of myeloid neoplasms evolves over the years and increasingly considers molecular abnormalities to prove the clonal hematopoiesis. In addition to morphological clues, the detection of JAK2, MPL and CALR mutations are considered driver events belonging to the major diagnostic criteria of BCR::ABL1-negative MPN. This highlights the preponderant place of molecular features in the MPN diagnosis. Moreover, the advent of next-generation sequencing (NGS) allowed the identification of additional somatic mutations involved in clonal hematopoiesis and playing a role in the prognosis of MPN. Nowadays, careful cytomorphology and molecular biology are inseparable and complementary to provide a specific diagnosis and to permit the best follow-up of these diseases.

A 68-Year-Old Man with a Cytogenetic Diagnosis of Chronic Myeloid Leukemia and Bone Marrow Findings of Philadelphia Chromosome Translocation Between the Long Arm of Chromosomes 9 and 22, Leading to the BCR-ABL1 Fusion Gene and V617F Mutation in the JAK2 Gene

BACKGROUND Breakpoint cluster region (BCR)-Abelson murine leukemia (ABL1) and Janus Kinase-2 (JAK2) mutations have been thought to be mutually exclusive in myeloproliferative neoplasms (MNPs), but recent data suggest that they can occur together. CASE REPORT A 68-year-old man was referred to the hematology clinic because of an elevated white blood cell count. His medical history included type II diabetes mellitus, hypertension, and retinal hemorrhage. Fluorescence in situ hybridization analysis of the bone marrow was positive for BCR-ABL1 in 66/100 cells. Conventional cytogenetics was positive for the Philadelphia chromosome in 16/20 counted cells. The percentage of BCR-ABL1 was 12%. Considering the patient's age and medical comorbidities, he was started on imatinib 400 mg once daily. Further tests showed JAK2 V617F mutation positivity and absence of acquired von Willebrand disease. He was then started on aspirin 81 mg and hydroxyurea 500 mg once daily, which was later increased to 1000 mg daily. The patient achieved a major molecular response after 6 months of treatment, with undetectable BCR-ABL1 levels. CONCLUSIONS BCR-ABL1 and JAK2 mutations can co-existence in MNPs. Physicians must suspect the presence of one of the MPNs in chronic myeloid leukemia (CML) patients with persistent or increased thrombocytosis, an atypical course of the disease, or hematological abnormalities despite evidence of response or remission of CML. Therefore, testing for JAK2 should be performed accordingly. Combining cytoreductive therapy with tyrosine kinase inhibitors (TKIs) is a therapeutic option when both mutations are present, and TKI alone is not sufficient to control peripheral blood cell counts.

JAK2-V617F is a negative regulation factor of SHIP1 protein and thus influences the AKT signaling pathway in patients with Myeloproliferative Neoplasm (MPN)

BACKGROUND

Myeloproliferative neoplasms (MPN) are a group of chronic haematological disorders. At the molecular level of MPN cells, the gain-of-function mutation V617F of the Janus kinase 2 (JAK2) leads to a constitutive activation of the downstream signaling cascade and is a conventional criteria for diagnosis. Here, the functional role of the tumor suppressor SHIP1 (SH2 domain containing inositol-5 phosphatase 1) in the pathogenesis of MPNs was investigated.

METHODS

Primary blood samples of MPN-patients were analysed using Western Blot technique regarding the level of SHIP1 expression. Moreover, SHIP1 and SHIP1-mutations were lentivirally transduced in the JAK2-V617F-positive UKE-1 cell line and expression was monitored over time. In addition, we examined SHIP1 reconstitution by inhibition of JAK2-V617F. Furthermore, we transfected SHIP1-expressing cells with a JAK2-V617F respectively a BCR-ABL construct and investigated changes in SHIP1 expression.

RESULTS

Four out of five MPN-patient samples showed a loss or a reduction in SHIP1 expression. We identified JAK2 as a negative regulator of SHIP1 expression in MPN cells and inhibition of JAK2-V617F implicates a reconstituted SHIP1 expression. This is significant because SHIP1 negatively regulates the AKT signaling pathway and in consequence the reconstitution of SHIP1 expression leads to a decreased cell growth. Moreover, we examined the impact of SHIP1 and patient-derived SHIP1-mutations on AKT phosphorylation and show the benefit of a combined therapy in MPN cells with inhibitors of the AKT/mTOR pathway.

CONCLUSION

In summary, the data suggest that SHIP1 may play a role during the development of MPNs and could be the basis for establishing a targeted therapy.

A Case Report of BCR-ABL-JAK2-Positive Chronic Myeloid Leukemia with Complete Hematological and Major Molecular Response to Dasatinib

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm (MPN) that harbors the Philadelphia chromosomal translocation resulting in the uncontrolled production of mature granulocytes. Commonly, patients are diagnosed with CML during blood work for other reasons or enlarged spleen. The diagnosis is based on WHO criteria that require the demonstration of Philadelphia chromosome. Typically, JAK2 mutation is not found in BCR-ABL1-positive MPN (CML). Most patients with CML are JAK2 negative. It is rare for CML Philadelphia-positive patients to have a coexisting JAK2 mutation. Little is known regarding the effect of JAK2 mutation on the disease course of CML, the complications, and the response to treatment. We report the case of a 57-year-old man with no previous medical illness who presented with elevated white blood cell count on perioperative assessment for hernial repair; on further workup, he was diagnosed with Philadelphia-positive CML. He was found to have JAK2 mutation and was started on treatment with dasatinib and achieved hematological and cytogenetic remission with loss of the JAK2 mutation. Patients with JAK2-positive BCR-ABL-positive CML had a good hematological and cytogenetic response to dasatinib. In such rare coexistence of JAK and BCR-ABL, dasatinib is a good option due to multi-kinase activity.

Co-existence of BCR-ABL and JAK2V617F mutation in resistant chronic myeloid leukemia in the imatinib era: Is there a correlation?

INTRODUCTION

Diagnoses of myeloproliferative disorder is based on molecular marker. Chronic Myeloid Leukemia and Myeloproliferative neoplasms were considered mutually exclusive and co-existence of BCR/ABL1 and JAK2 mutation is a rare phenomenon.

CASE REPORT

Here, we present two cases of co-existence of BCR-ABL and JAK2V617F positivity. We characterize the course of the disease, mainly the minimal residual disease.Management and outcome: The two cases was initially managed as Chronic Myeloid Leukemia and treated by TKI inhibitors. The first one was diagnosed in 2010. He started the first line of TKI, and then switched to second line without obtaining a major molecular response. Hence he was tested for JAK2V617F mutation and positivity was diagnosed. The second patient showed Chronic Myeloid Leukemia phenotype with coexistence of BCR/ABL1 and JAK2 mutation at diagnosis. Molecular monitoring reveals a high BCR-ABL1 transcript level (20%) at the last follow-up (12 months).

DISCUSSION

Ours results highlight that JAK2V617F/BCR-ABL double positivity may be a potential marker of resistance in Chronic Myeloid Leukemia and clonal molecular analysis is mandatory to elucidate the mechanism. Moreover, the combination of JAK and TKI inhibitors might be effective and potentially be guided by molecular monitoring of minimal residual disease.

Concurrent JAK2-Positive Myeloproliferative Disorder and Chronic Myelogenous Leukemia: A Novel Entity? A Case Report With Review of the Literature

JAK2 V617F mutation and BCR-ABL translocation have been considered to be mutually exclusive. However, many cases where both hits coexisted have been reported. We have personally managed a case too. We believe this hybrid entity is underdiagnosed. Thus, we decided to shed light on this "double hit" disease to improve its diagnosis and optimize its treatment. We reviewed the English literature in PubMed since JAK2 discovery. We found 33 cases reported so far. We summarized patient characteristics and analyzed possible interactions between JAK2 and BCR-ABL clones.

Generalized granuloma annulare associated with essential thrombocythemia

The only myeloproliferative neoplasm associated with generalized granuloma annulare (GA) is chronic myelogenous leukemia (CML). We present the first reported case of GA in a patient with essential thrombocythemia (ET). Future work investigating the shared pathophysiology of GA-associated CML and ET may improve our understanding of GA pathophysiology and treatment.

Emergence of BCR-ABL1 Chronic Myeloid Leukemia in a JAK2-V617F Polycythemia Vera

Emergence of a new chronic myeloid neoplasm in the setting of a previous one, or their concomitant appearance seems to be a rare event, but plenty of cases have been reported. We describe the case of a patient with JAK2-V617F polycythemia vera, which looses JAK2 clone and develops overt BCR-ABL1 chronic myeloid leukemia after 6 years. Once treatment with tyrosine kinase inhibitors controls BCR-ABL1 clone, JAK2 clone arises again. In this report, we review the literature and discuss the clonal relationship of this event in light of the new molecular data.

Coexistence of breakpoint cluster region-Abelson1 rearrangement and Janus kinase 2 V617F mutation in chronic myeloid leukemia: A case report

BACKGROUND

The Janus kinase 2 (JAK2) V617F mutation is common in patients with breakpoint cluster region-Abelson1 (BCR-ABL1)-negative myeloproliferative neoplasms, including polycythemia vera, essential thrombocythemia and primary myelofibrosis, but is rarely detected in BCR-ABL1-positive chronic myeloid leukemia (CML) patients. Here, we report a CML patient with both a BCR-ABL1 rearrangement and JAK2 V617F mutation.

CASE SUMMARY

A 45-year-old Chinese woman was admitted to our department with a history of significant thrombocytosis for 20 d. Color Doppler ultrasound examination showed mild splenomegaly. Bone marrow aspiration revealed a karyotype of 46, XX, t(9;22)(q34;q11.2) in 20/20 metaphases by cytogenetic analysis, rearrangement of BCR-ABL1 (32.31%) by fluorescent polymerase chain reaction (PCR) and mutation of JAK2 V617F (10%) by PCR and Sanger DNA sequencing. The patient was diagnosed with CML and JAK2 V617F mutation. Following treatment with imatinib for 3 mo, the patient had an optimal response and BCR-ABL1 (IS) was 0.143%, while the mutation rate of JAK2 V617F rose to 15%.

CONCLUSION

Emphasis should be placed on the detection of JAK2 mutation when CML is diagnosed to distinguish JAK2 mutation-positive CML and formulate treatment strategies.

The co-occurrence of driver mutations in chronic myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are clonal disorders characterized by proliferation of one or more elements of the myeloid lineage. Key genetic aberrations include the BCR-ABL1 gene rearrangement in Philadelphia chromosome-positive chronic myelogenous leukemia (CML) and JAK2/MPL/CALR aberrations in Philadelphia chromosome-negative MPNs. While thought to be mutually exclusive, occasional isolated reports of coexistence of BCR-ABL1 and JAK2, and JAK2 with MPL or CALR aberrations have been described. Given the paucity of data, clinical characteristics and outcome of patients harboring concurrent Philadelphia-positive and Philadelphia-negative mutations or dual Philadelphia-negative driver mutations have not been systematically evaluated, and their clinical relevance is largely unknown. It is difficult to determine the true relevance of co-existing driver mutations on outcomes given the rarity of its occurrence. In this case series, we describe those patients who had dual driver mutations detected at any point during the course of their disease and characterized their clinical and laboratory features, bone marrow pathology, and overall disease course.

Mutations in myeloproliferative neoplasms - their significance and clinical use

INTRODUCTION

Clonal hematologic diseases of the blood such as polycythemia vera, essential thrombocythemia and primary myelofibrosis belong to the BCR-ABL negative Myeloproliferative Neoplasms (MPN). These diseases are characterized by clonal expansion of hematopoietic precursor cells followed by increased production of differentiated cells of the myeloid lineage. Initiation of clonal hematopoiesis, formation of a clinical phenotype as well as disease progression form part of MPN disease evolution. The disease is driven by acquired somatic mutations in critical pathways such as cytokine signaling, epigenetic regulation, RNA splicing, and transcription factor signaling. Areas covered: The following review aims to provide an overview of the mutational landscape of MPN, the impact of these mutations in MPN pathogenesis as well as their prognostic value. Finally, a summary of how these mutations are being used or could potentially be used for the treatment of MPN patients is presented. Expert commentary: The genetic landscape of MPN patients has been successfully dissected within the past years with the advent of new sequencing technologies. Integrating the genetic information within a clinical setting is already benefitting patients in terms of disease monitoring and prognostic information of disease progression but will be further intensified within the next years.

Clinical characteristics and whole exome/transcriptome sequencing of coexisting chronic myeloid leukemia and myelofibrosis

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell (HSC) disorders that can be classified on the basis of genetic, clinical, phenotypic features. Genetic lesions such as JAK2 mutations and BCR-ABL translocation are often mutually exclusive in MPN patients and lead to essential thrombocythemia, polycythemia vera, or myelofibrosis or chronic myeloid leukemia, respectively. Nevertheless, coexistence of these genetic aberrations in the same patient has been reported. Whether these aberrations occur in the same stem cell or a different cell is unclear, but an unstable genome in the HSCs seems to be the common antecedent. In an effort to characterize the underlying genetic events that might contribute to the appearance of more than one MPN in a patient, we studied neoplastic cells from patients with dual MPNs by next-generation sequencing. We observed that most patients with two MPNs harbored mutations in genes known to contribute to clonal hematopoiesis through altered epigenetic regulation such as TET2, ASXL1/2, SRSF2, and IDH2 at varying frequencies (1%-47%). In addition, we found that some patients also harbored oncogenic mutations in N/KRAS, TP53, BRAF, EZH2, and GNAS at low frequencies, which probably represent clonal evolution. These findings support the hypothesis that hematopoietic cells from MPN patients harbor multiple genetic aberrations, some of which can contribute to clonal dominance. Acquiring mutations in JAK2/CALR/MPL or the BCR-ABL translocation probably drive the oncogenic phenotype towards a specific MPN. Further, we propose that the acquisition of BCR-ABL in these patients is frequently a secondary event resulting from an unstable genome.

MYC Deregulation in Primary Human Cancers

MYC regulates a complex biological program by transcriptionally activating and repressing its numerous target genes. As such, MYC is a master regulator of many processes, including cell cycle entry, ribosome biogenesis, and metabolism. In cancer, the activity of the MYC transcriptional network is frequently deregulated, contributing to the initiation and maintenance of disease. Deregulation often leads to constitutive overexpression of MYC, which can be achieved through gross genetic abnormalities, including copy number alterations, chromosomal translocations, increased enhancer activity, or through aberrant signal transduction leading to increased MYC transcription or increased MYC mRNA and protein stability. Herein, we summarize the frequency and modes of MYC deregulation and describe both well-established and more recent findings in a variety of cancer types. Notably, these studies have highlighted that with an increased appreciation for the basic mechanisms deregulating MYC in cancer, new therapeutic vulnerabilities can be discovered and potentially exploited for the inhibition of this potent oncogene in cancer.

Laboratory Investigation of Myeloproliferative Neoplasms (MPNs): Recommendations of the Canadian Mpn Group

OBJECTIVES

To standardize diagnostic investigations for myeloproliferative neoplasms (MPNs) to increase homogeneity in patient care and to streamline diagnostic approaches in the most efficient and cost-effective manner.

METHODS

The development of Canadian expert consensus recommendations for the diagnosis of MPNs began with a review of the following: clinical evidence, daily practice, existing treatment guidelines, and availability of diagnostic tools. Each group member was assigned a specific topic, which they discussed with the entire group during several consensus meetings.

RESULTS

This document provides the Canadian MPN group's recommendations, proposed diagnostic algorithms, and background evidence upon which decisions were made.

CONCLUSIONS

Standardization of diagnostic investigations will increase homogeneity in patient care and provide a foundation for future clinical research in this rapidly evolving therapeutic area. Streamlining diagnostic approaches in the most efficient and cost-effective manner will also result in significant cost saving for the health care system.

ASXL1 and JAK2V617F gene mutation screening in Iranian patients with chronic myeloid leukemia

AIM

In recent years, a few cases of chronic myeloid leukemia (CML) have been reported with both BCR-ABL and JAK2V617F mutations. Moreover, mutations in the additional sex comb-like 1 (ASXL1) gene were recently shown in various myeloid malignancies.There were no previous studies investigating the incidence of the ASXL1 and JAK2V617F mutations in Iranian patients with CML. Consequently, this study focuses on the analysis of these mutations in patients with CML.

METHODS

In total, 66 patients with a clinical diagnosis of CML were examined at the time of diagnosis. Thirty healthy subjects were checked as controls. Exon 12 of ASXL1 was amplified from genomic DNA and bidirectionally sequenced. We also performed JAK2V617F screening by amplification refractory mutation system-polymerase chain reaction and sequencing.

RESULTS

Mutations in the ASXL1 gene were found in five out of 66 CML patients (7.6%). We identified a novel variant (c.1968G > A, p.Asp656Asn) in one of the patients that has not been reported before. We also identified BCR-ABL and JAK2V617F mutations simultaneously in four patients (6%).

CONCLUSION

Our demonstration of ASXL1 mutation, a putative tumor suppressor gene, represents an important molecular abnormality in CML. We also showed that concomitant detection of BCR-ABL and JAK2V617F mutations has a relatively high incidence in Iranian patients.