The Philadelphia translocation and pre-existing myeloproliferative disorders

Philadelphia Chromosome Positive Chronic Myelogenous Leukemia Blastic Crisis in a Patient with Unusual Primary Myelofibrosis Characteristics; A Case Report

INTRODUCTION

Myeloproliferative neoplasms (MPNs) are divided into BCR-ABL positive Chronic myeloid leukemia (CML) and BCR-ABL negative MPNs including Polycythemia vera (PV), Essential Thrombocythemia (ET) and Primary myelofibrosis (PMF). Evaluation of the Philadelphia chromosome in MPNs is a diagnostic requirement for classic CML.

CASE REPORT

In 2020, a 37-year-old woman with negative cytogenetic testing for Janus kinase2 (JAK2), Calreticulin (CALR), myeloproliferative leukemia virus oncogene (MPL), and positive for BCR-ABL1 mutation with reticular fibrosis in bone marrow was diagnosed as CML. Some years ago, the patient had been diagnosed with PMF with evidence of histiocytic necrotizing lymphadenitis or Kikuchi-Fujimoto disease (KFD). The BCR-ABL fusion gene was initially evaluated which was negative. Then, Cutaneous squamous cell carcinoma (cSCC) was confirmed by Dermatopathologist with palpable splenomegaly and high white blood cell (WBC) count with basophilia. Finally, BCR-ABL was detected positive by the fluorescence in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qRT-PCR). In fact, the co-occurrence of PMF with CML was identified.

CONCLUSION

This case study highlighted the importance of some cytogenetic methods in the detection and classification of MPNs. It is recommended that physicians pay more attention to it and be aware of the planning treatment.

BCR-ABL1 is a secondary event after JAK2V617F in a patient with essential thrombocythemia who develop chronic myeloid leukemia

Several cases such as myeloproliferative neoplasms (MPN) with the coexistence of JAK2 and BCR-ABL have been reported. However, cases of transformation of essential thrombocythemia (ET) into chronic myeloid leukemia (CML) during the disease progression were rarely reported. Here, we report the case of a patient with JAK2 V617F- positive ET who subsequently acquired BCR-ABL1, which transformed the disease into CML after 10 years from the initial diagnosis. In this study, we dynamically monitored JAK2 V617F and BCR-ABL and observed multiple gene mutations, including IDH2, IDH1, ASXL1, KRAS, and RUNX1. It is important to be aware of this potentially clone evolution in disease progression.

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.

A Case of Chronic Myelogenous Leukemia Occurring in a Patient Treated for Essential Thrombocythemia

Patient: Female, 49

Final Diagnosis: Essential thrombocythemia with CML

Symptoms: Decreased appetite • fatigue • weight loss

Medication: —

Clinical Procedure: —

Specialty: Hematology

Coexisting driver mutations in MPN: clinical and molecular characteristics of a series of 11 patients

OBJECTIVES

CML, PV, ET and PMF are so called classical MPN with distinct clinical phenotypes. The discovery of the BCR-ABL1 translocation and mutations in driver genes JAK2, MPL and CALR has provided novel insights in their pathogenesis. While these mutations are thought to be mutually exclusive, rare cases of MPN with coexisting driver mutations have been reported. However, little is known about the clinical, biological and molecular characteristics of these patients and the interaction of the neoplastic clones.

METHODS

We retrospectively studied 11 MPN patients with coexisting driver mutations (JAK2 V617F + BCR-ABL1: n = 8; CALR type 2 + BCR-ABL1: n = 1; JAK2 V617F + MPL W515: n = 1; JAK2 V617F + CALR type 1: n = 1). To assess possible associated molecular aberrations, we analysed DNA of six patients using NGS.

RESULTS

In four CML patients, decreasing BCR-ABL1 transcript levels with increasing JAK2 V617F allele burden under TKI were observed. This strongly suggests that the coexistence of driver mutations originates from two different clones growing independently. Additional somatic mutations were detected in 5 out of 6 (83%) patients affecting 4 different genes, confirming the heterogeneity of this study cohort. Suboptimal response to TKI was observed with a higher frequency (4/8 patients) than reported in conventional series of CML and the overall tolerance of treatment with hydroxyurea and/or imatinib in our series was poor.

CONCLUSION

Given the emergence of NGS in clinical practice, more similar cases will be identified in the coming years. The optimal treatment strategy for this rare group of patients is uncertain and toxicity of combination treatment may have to be considered.

Frequency of JAK2 V617F mutation in patients with Philadelphia positive Chronic Myeloid Leukemia in Pakistan

Background and Objective: Co-existence of myeloproliferative disorders (MPD) and Janus associated kinase 2 mutation (JAK2 V617F) is a well-established fact. Only few case reports are available showing presence of JAK2 V617F mutation in chronic myeloid leukemia (CML). Purpose of this study was to determine the frequency of JAK2 V617F mutation in Philadelphia Chromosome positive (Ph ⁺) CML patients in Pakistan.

Methods: The study was conducted from August 2009 to July 2010 at Civil Hospital and Baqai Institute of Hematology (BIH) Karachi. Blood samples from 25 patients with CML were collected. Multiplex reverse transcription polymerase chain reaction (RT-PCR) was performed for Breakpoint Cluster Region – Abelson (BCR-ABL) rearrangement. Conventional PCR was performed for JAK2 V617F mutation on BCR-ABL positive samples.

Results: All 25 samples showed BCR-ABL rearrangement. Out of these 11 samples (44%) had JAK2 V617F mutation; the remaining 14 (56%) cases showed JAK2 617V wild type.

Conclusion: It is concluded that the co-existence of Ph ⁺CML and JAK2 V617F mutation is possible.

Impressive thrombocytosis evolving in a patient with a BCR-ABL positive CML in major molecular response during dasatinib treatment unmasks an additional JAK2V617F

We present a case of a 42-year old female with the rare diagnosis of a myeloproliferative syndrome harboring both a BCR-ABL transclocation and a JAK2V617F mutation.

Initially diagnosed with a CML, the patient underwent treatment with imatinib followed by dasatinib. Despite a major molecular response, the patient developed a thrombocytosis. Molecular analyses revealed a heterozygous JAK2V617F mutation, which was detected retrospectively in the bone marrow at the time of CML diagnosis.

This case underlines the complexity of MPS pathogenesis. For the clinician, a JAK2 mutational screening should be performed in CML patients without hematological response in the absence of BCR-ABL.

Concomitant presence of JAK2 V617F mutation and BCR-ABL translocation in a pregnant woman with polycythemia vera

In 2007, a 27-year-old woman presented with mild splenomegaly. Blood counts showed hemoglobin (Hb): 17.8 g/dl, HCT: 56% and Red blood cells: 6.45×10(12)/L. Bone marrow examination disclosed a hypercellular marrow. Molecular analysis showed the presence of the JAK2 V617F mutation and BCR-ABL/BCR mRNA b3a2 transcript. A diagnosis of BCR-ABL-positive polycythemia vera (PV) was made. In 2009, she had nulipar pregnancy and treated with interferon-alpha. She delivered a healthy girl infant at 37 weeks. This case report suggests that in a PV pregnant woman with a concomitant presence of JAK2 V617F mutation and BCR-ABL translocation, the administration of interferon during the pregnancy could lead to a safe pregnancy and delivery.

Emergence of chronic myelogenous leukemia from a background of myeloproliferative disorder: JAK2V617F as a potential risk factor for BCR-ABL translocation

We report the emergence of chronic myelogenous leukemia (CML) in a patient with JAK2V617F-positive polycythemia vera after 15 years of phlebotomy. The polycythemia vera clinical and molecular findings were suppressed at the time of CML diagnosis, only to re-emerge after the leukemia was successfully treated with imatinib. We explored the potential association between myeloproliferative disorders and CML in the context of the current literature and found a higher-than-expected coincidence based on known epidemiologic data for each specific condition. We hypothesize that myeloproliferative disorder (JAK2V617F or molecular events that cause JAK2V617F) is a risk factor for CML (BCR-ABL translocation). Because of therapeutic implications, clinicians should be aware that the conditions co-occur more frequently than once thought.

Emergence of chronic myelogenous leukemia during treatment for essential thrombocythemia

A 72-year-old male patient was initially diagnosed with essential thrombocythemia (ET), a Philadelphia chromosome-negative (Ph1(-)) chronic myeloproliferative disorder (CMPD), and was treated with hydroxyurea (HU). After 9 years of diagnosis of ET, his peripheral leukocytes gradually increased, while his platelet count showed a decrease. Bone marrow analysis disclosed Ph-positive chronic myelogenous leukemia (CML) in the chronic phase. Administration of imatinib mesylate (IM), a Bcr-Abl tyrosine kinase inhibitor (TKI), induced complete hematologic response in a month, but was discontinued after 4 months because of Grade 3 pleural effusion (PE). The treatment was switched to nilotinib which successfully induced a complete cytogenetic response (CCyR) after 5 months of TKI therapy and resolved the PE. Despite CCyR, however, ET recurred. Since then, the patient has been treated for 8 months with a combination of nilotinib and HU which has successfully controlled both CML and ET. This report includes a review of the characteristics of 15 reported cases with co-occurrence of CML and Bcr-Abl-negative CMPDs, including ours. Although rare, care needs to be taken since, despite the often similar clinical features of the two diseases, they require completely different treatments.

Emergence of therapy-unrelated CML on a background of BCR-ABL-negative JAK2V617F-positive chronic idiopathic myelofibrosis

We report the emergence of a chronic myeloid leukaemia (CML) during the course of a JAK2V617F-positive chronic idiopathic myelofibrosis (CIMF) in the absence of any myelosuppressive treatment. Although a response to imatinib was observed, the underlying myelofibrosis persisted after treatment and hydroxyurea was finally added to control the persistent thrombocytosis. Such rare patients with co-existing BCR-ABL translocation and JAK2V617F mutation must be identified in view of the possibility of targeted therapies. Moreover, the detection of BCR-ABL translocation appears to be crucial especially in the case of treated CIMF with an atypical course to identify CML before acute transformation.

Transformation of polycythemia vera to chronic myelogenous leukemia

Transformation of polycythemia vera to chronic myelogenous leukemia is a rare event. We report 2 women with long-standing polycythemia vera who developed chronic myelogenous leukemia. Both patients had no BCR/ABL1 fusion at the time of polycythemia vera diagnosis but were positive for the fusion at chronic myelogenous leukemia onset. Most patients with polycythemia vera have JAK2(V617F) mutation. Analysis of an archival bone marrow aspirate sample from 1 patient showed a heterozygous mutation status. The blood and bone marrow samples from the other patient showed the presence of homozygous JAK2(V617F) mutation and BCR/ABL1 fusion. The possible pathogenesis of such an event is discussed in the light of current literature.

P210 Bcr-abl tyrosine kinase interaction with histone deacetylase 1 modifies histone H4 acetylation and chromatin structure of chronic myeloid leukaemia haematopoietic progenitors

The BCR-ABL fusion gene, originating from the balanced (9;22) translocation, is the molecular hallmark and the causative event of chronic myeloid leukaemia (CML). The interactions of its p210 protein constitutively activated and improperly confined to the cytoplasm with multiple regulatory signals of cell cycle progression, apoptosis and self-renewal, induce the illegitimate enlargement of clonal haematopoiesis and genetic instability that drives its progression towards the fully transformed phenotype of blast crisis. However, its effects on the basic transcription machinery and chromatin remodelling are unknown. Our study underscored histone H4 hyperacetylation associated with p210 tyrosine kinase in vitro and in vivo and its role in BCR-ABL transcription. Histone H4 hyperacetylation proceeds, at least partly, from the 'loss of function' of histone deacetylase 1 protein, a critical component of Rb-mediated transcriptional repression, in consequence of its cytoplasmatic compartmentalisation.

Essential thrombocythaemia: challenges and evidence-based management

Essential thrombocythaemia was first described over 70 years ago. This condition is dominated by thrombotic and haemorrhagic complications and, in the long-term, by risk of transformation to myelofibrosis and/or acute leukaemia. However, it is heterogeneous both clinically and biologically. Here, a review of current concepts in disease aetiology and management is offered with reference to recent focused reviews where appropriate. In addition, five specific areas are discussed in detail: the role of the trephine biopsy, the disease entity prefibrotic myelofibrosis; the recently described Janus kinase 2 (JAK2) mutations; the leukaemogenicity of hydroxyurea (hydroxycarbamide); and lastly, the implications of the results of the Medical Research Council Primary Thrombocythaemia 1 study are explored.

Management of polycythemia vera and essential thrombocythemia

The optimal management of patients with polycythemia vera (PV) and essential thrombocythemia (ET) continues to be controversial. Both diseases present diagnostic challenges and there is a paucity of data from randomized clinical trials to guide therapeutic decisions. However, the past two years have seen major advances in our understanding of these myeloproliferative disorders (MPD). First, the ECLAP study demonstrated the anti-thrombotic efficacy of aspirin in patients with PV. Second, the PT-1 trial, the largest randomized study of any MPD, has provided much needed guidance on the optimal management of patients with ET. Third, the identification of a single JAK2 mutation in most patients with PV, and in some of those with ET, illuminates the pathogenesis of these diseases and raises questions about the boundary between them. For the purpose of management decisions, it remains appropriate to consider them as separate entities for the time being. However, as we learn more about the clinical significance of the JAK2 mutation, it seems likely that the coming years will see major changes in the way we classify and manage these disorders.