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Sellar R, Losman JA. Targeting Aberrant Signaling in Myeloid Malignancies: Promise Versus Reality. Hematol Oncol Clin North Am 2017; 31:565-576. [PMID: 28673388 DOI: 10.1016/j.hoc.2017.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Clonal myeloid disorders are characterized by genetic alterations that activate cytokine signaling pathways and stimulate cell proliferation. These activated signaling pathways have been extensively studied as potential therapeutic targets, and tyrosine kinase inhibitors have indeed had extraordinary success in treating BCR/ABL-positive chronic myeloiud leukemia. However, although inhibitors of other activated kinases have been developed that perform well in preclinical studies, the therapeutic efficacy of these drugs in patients has been unimpressive. This article discusses potential reasons for these discordant results and outlines recent scientific advances that are informing future efforts to target activated kinases in clonal myeloid disorders.
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Abstract
Myeloproliferative neoplasms are driven by activated JAK2 signaling due to somatic mutations in JAK2, the thrombopoietin receptor MPL or the chaperone calreticulin in hematopoietic stem/progenitor cells. JAK2 inhibitors have been developed, but despite clinical benefits, they do not signficantly reduce the mutant clone. Loss of response to JAK2 inhibitors occurs and several mechanisms of resistance, genetic and functional, have been identified. Resistance mutations have not been reported in MPN patients suggesting incomplete target inhibition. Alternative targeting of JAK2 by HSP90 inhibitors or type II JAK2 inhibition overcomes resistance to current JAK2 inhibitors. Additional combined therapy approaches are currently being evaluated.
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Somatic mutations of calreticulin in myeloproliferative neoplasms. Int J Hematol 2017; 105:743-747. [PMID: 28470469 DOI: 10.1007/s12185-017-2246-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 04/26/2017] [Indexed: 11/27/2022]
Abstract
Recurrent somatic mutations in calreticulin (CALR) gene that encodes a molecular chaperone residing in the endoplasmic reticulum were identified in 2013 in a subset of patients with myeloproliferative neoplasms (MPNs). All of these mutations found in patients were either small insertion or deletion in a narrow region on exon 9 of CALR gene, and caused +1 frameshift in the reading frame for the translation of the carboxyl-terminus of CALR. Because of this unique feature, the CALR mutation is believed to be a gain-of-function mutation. However, there was essentially no rationale model to implicate the involvement of mutant CALR in the pathogenesis of MPN or other malignancies. Based on the recent findings, this review summarizes a novel molecular mechanism by which this mutant molecular chaperone constitutively activates the cytokine receptor to induce cellular transformation in MPNs.
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Haslam K, Langabeer SE. Who to screen for calreticulin mutations? An audit of real-life practice and review of current evidence. Eur J Intern Med 2017; 40:e22-e23. [PMID: 28132789 DOI: 10.1016/j.ejim.2017.01.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
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Abstract
Myeloproliferative neoplasms (MPNs) are diseases of excess cell proliferation from bone marrow precursors. Two classic MPNs, polycythemia vera (PV) and essential thrombocytosis (ET), are conditions of excess proliferation of red blood cells and platelets, respectively. Although PV and ET involve different cells in the myeloid lineage, their clinical presentations have shared features, consistent with overlapping mutations in growth factor signaling. The management of both diseases involves minimizing the risk of thrombotic and hemorrhagic complications. Both PV and ET can progress to myelofibrosis or acute myeloid leukemia, portending a poor prognosis. MPNs can also present as primary myelofibrosis.
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Lekovic D, Gotic M, Milic N, Zivojinovic B, Jovanovic J, Colovic N, Milosevic V, Bogdanovic A. Predictive parameters for imatinib failure in patients with chronic myeloid leukemia. Hematology 2017; 22:460-466. [PMID: 28327053 DOI: 10.1080/10245332.2017.1302179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVE Until recently, imatinib was the standard first-line treatment in chronic myeloid leukemia (CML). The inclusion of nilotinib and dasatinib as first-line options in CML raised a debate on treatment selection. The aim of our study was to analyze predictive parameters for imatinib response as the first-line treatment of CML patients. METHODS The study included 168 consecutive patients with chronic phase Philadelphia-positive CML who were diagnosed and treated with Imatinib 400 mg once daily at a single university hospital. Numerous parameters were analyzed in terms of imatinib response including comorbidities as well as occurrence of second malignancies. RESULTS After the median follow-up of 87 months in 61 patients (36.3%), the imatinib failure was verified. Cox regression analysis identified hepatomegaly (p = 0.001), leukocytosis ≥ 100 × 109/l (p = 0.001), blood blasts ≥ 1% (p = 0.002), and the presence of additional cytogenetic aberrations (p = 0.002) as predictors of Imatinib failure. Based on these findings, a new prognostic model was developed according to which imatinib failure had 17% (8/47) of patients in low risk, 34.9% (30/86) of patients in intermediate risk, and 76.7% (23/30) of patients in high-risk group (HR = 3.973, 95% CI for HR 2.237-7.053, p < 0.001). CONCLUSION The new score allows better selection of patients who are suitable for treatment with imatinib and may guideline the clinical decision for front-line treatment of CML.
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Boddu P, Falchi L, Hosing C, Newberry K, Bose P, Verstovsek S. The role of thrombocytapheresis in the contemporary management of hyperthrombocytosis in myeloproliferative neoplasms: A case-based review. Leuk Res 2017; 58:14-22. [PMID: 28380402 DOI: 10.1016/j.leukres.2017.03.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/04/2017] [Accepted: 03/13/2017] [Indexed: 12/28/2022]
Abstract
Extreme thrombocytosis induces an acquired thrombotic-hemorrhagic diathesis, and left uncontrolled is a harbinger of potentially fatal vascular complications. Currently, cytoreduction with medical therapy remains the mainstay of hyperthrombocytosis management. However, it offers a less-than-ideal option in situations where a rapid reduction in platelets is urgently needed, as in the presence of vital end-organ ischemia or to ameliorate of life-threatening hemorrhage. The role of thrombocytapheresis, or plateletpheresis, in hyperthrombocytosis has become increasingly obsolete given the proactive titration of cytoreductive therapies and early identification and correction of reversible causes of reactive thrombocytosis. Despite its narrowed indications, plateletpheresis continues to offer a valuable temporizing measure in platelet count reduction before cytoreductive agents exert their maximal effect. In this context, it is important for the treating physician to be aware of the symptoms and risks associated with hyperthrombocytosis to inform best clinical practices. In this review, we discuss the role of plateletpheresis in the modern-day management of hyperthrombocytosis in patients with myeloproliferative neoplasms through a case based review of the literature. It becomes apparent throughout the discussion that the decision to perform plateletpheresis should be individualized based upon the clinical scenario, degree of thrombocytosis, available infrastructure and every patient's risk profile.
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Iurlo A, Cattaneo D. Treatment of Myelofibrosis: Old and New Strategies. Clin Med Insights Blood Disord 2017; 10:1179545X17695233. [PMID: 28579852 PMCID: PMC5428134 DOI: 10.1177/1179545x17695233] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 01/30/2017] [Indexed: 01/19/2023]
Abstract
Myelofibrosis (MF) is a BCR-ABL1-negative myeloproliferative neoplasm that is mainly characterised by reactive bone marrow fibrosis, extramedullary haematopoiesis, anaemia, hepatosplenomegaly, constitutional symptoms, leukaemic progression, and shortened survival. As such, this malignancy is still orphan of curative treatments; indeed, the only treatment that has a clearly demonstrated impact on disease progression is allogeneic haematopoietic stem cell transplantation, but only a minority of patients are eligible for such intensive therapy. However, more recently, the discovery of JAK2 mutations has also led to the development of small-molecule JAK1/2 inhibitors, the first of which, ruxolitinib, has been approved for the treatment of MF in the United States and Europe. In this article, we report on old and new therapeutic strategies that proved effective in early preclinical and clinical trials, and subsequently in the daily clinical practice, for patients with MF, particularly concerning the topics of anaemia, splenomegaly, iron overload, and allogeneic stem cell transplantation.
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Krichevsky S, Prus E, Perlman R, Fibach E, Ben-Yehuda D. The JAK2V617F mutation in normal individuals takes place in differentiating cells. Blood Cells Mol Dis 2017; 63:45-51. [PMID: 28126623 DOI: 10.1016/j.bcmd.2017.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 01/31/2023]
Abstract
The JAK2V617F mutation that results in a hyper-activation of the JAK2 kinase in the erythropoietin pathway is a molecular marker for myeloproliferative neoplasms. Using allele-specific Real-Time PCR, we detected the mutation in the blood of 17.3% (17/98) of normal donors; the mutant allele burden was, however, very low (<0.01% compared to >1% in polycythemia vera). It was much higher in differentiated blood cells in the peripheral blood than in undifferentiated CD34+ cells. Erythropoietin-stimulated differentiation of normal CD34+ cells in liquid culture increased the mutation frequency by 3.34-fold. When progenitors from 9 normal donors were grown in erythropoietin-stimulated semi-solid cultures, the mutation was found in 8.69% of the colonies, but only in <3% of the JAK2 alleles in each positive colony, suggesting that the mutation occurred only in a few cells per colony. In mouse erythroleukemia cells carrying human JAK2 DNA, wild-type or JAK2V617F, the frequencies of mutations from JAK2 wild-type to JAK2V617F and vice versa increased following erythroid differentiation. These results suggest that the mutation occurs and accumulates during differentiation. We hypothesize that genetic stability, which relies on DNA repair, is efficient in normal hematopoietic stem cells but is downgraded in differentiating cells, rendering them susceptible to mutations, including JAK2V617F.
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Lekovic D, Gotic M, Skoda R, Beleslin-Cokic B, Milic N, Mitrovic-Ajtic O, Nienhold R, Sefer D, Suboticki T, Buac M, Markovic D, Diklic M, Cokic VP. Bone marrow microvessel density and plasma angiogenic factors in myeloproliferative neoplasms: clinicopathological and molecular correlations. Ann Hematol 2016; 96:393-404. [PMID: 27924369 DOI: 10.1007/s00277-016-2890-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 11/27/2016] [Indexed: 01/02/2023]
Abstract
Increased angiogenesis in BCR-ABL1 negative myeloproliferative neoplasms (MPNs) has been recognized, but its connection with clinical and molecular markers needs to be defined. The aims of study were to (1) assess bone marrow (BM) angiogenesis measured by microvessel density (MVD) using CD34 and CD105 antibodies; (2) analyze correlation of MVD with plasma angiogenic factors including vascular endothelial growth factor, basic fibroblast growth factor, and interleukin-8; (3) examine the association of MVD with clinicopathological and molecular markers. We examined 90 de novo MPN patients (30 polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET)) and 10 age-matched controls. MVD was analyzed by immunohistochemistry "hot spot" method, angiogenic factors by immunoassay and JAK2V617F, and CALR mutations by DNA sequencing and allelic PCR. MVD was significantly increased in MPNs compared to controls (PMF > PV > ET). Correlation between MVD and plasma angiogenic factors was found in MPNs. MVD was significantly increased in patients with JAK2V617F mutation and correlated with JAK2 mutant allele burden (CD34-MVD: ρ = 0.491, p < 0.001; CD105-MVD: ρ = 0.276, p = 0.02) but not with CALR mutation. MVD correlated with leukocyte count, serum lactate dehydrogenase, hepatomegaly, and splenomegaly. BM fibrosis was significantly associated with CD34-MVD, CD105-MVD, interleukin-8, and JAK2 mutant allele burden. JAK2 homozygote status had positive predictive value (100%) for BM fibrosis. Patients with prefibrotic PMF had significantly higher MVD than patients with ET, and we could recommend MVD to be additional histopathological marker to distinguish these two entities. This study also highlights the strong correlation of MVD with plasma angiogenic factors, JAK2 mutant allele burden, and BM fibrosis in MPNs.
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Morotti A, Rocca S, Carrà G, Saglio G, Brancaccio M. Modeling myeloproliferative neoplasms: From mutations to mouse models and back again. Blood Rev 2016; 31:139-150. [PMID: 27899218 DOI: 10.1016/j.blre.2016.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/28/2016] [Accepted: 11/22/2016] [Indexed: 02/07/2023]
Abstract
Myeloproliferative neoplasms (MPNs) are defined according to the 2008 World Health Organization (WHO) classification and the recent 2016 revision. Over the years, several genetic lesions have been associated with the development of MPNs, with important consequences for identifying unique biomarkers associated with specific neoplasms and for developing targeted therapies. Defining the genotype-phenotype relationship in MPNs is essential to identify driver somatic mutations that promote MPN development and maintenance in order to develop curative targeted therapies. While studies with human samples can identify putative driver mutations, murine models are mandatory to demonstrate the causative role of mutations and for pre-clinical testing of specific therapeutic interventions. This review focuses on MPN mouse models specifically developed to assess the pathogenetic roles of gene mutations found in human patients, as well as murine MPN-like phenotypes identified in genetically modified mice.
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Wang J, Zhang B, Chen B, Zhou RF, Zhang QG, Li J, Yang YG, Zhou M, Shao XY, Xu Y, Xu XH, Ouyang J, Xu J, Ye Q. JAK2, MPL, and CALR mutations in Chinese Han patients with essential thrombocythemia. ACTA ACUST UNITED AC 2016; 22:145-148. [PMID: 27875935 DOI: 10.1080/10245332.2016.1252003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Mutations in Janus kinase 2 (JAK2), myeloproliferative leukemia (MPL), and CALR are highly relevant to Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms. METHODS Assessing the prevalence of molecular mutations in Chinese Han patients with essential thrombocythemia (ET), and correlating their mutational profile with disease characteristics/phenotype. RESULTS Of the 110 subjects studied, 62 carried the JAK2 V617F mutation, 21 had CALR mutations, one carried an MPL (W515) mutation, and 28 had non-mutated JAK2, CALR, and MPL (so-called triple-negative ET). Mutations in JAK2 exon 12 were not detected in any patient. Two ET patients had both CALR and JAK2 V617F mutations. Comparing the hematological parameters of the patients with JAK2 mutations with those of the patients with CALR mutations showed that the ET patients with CALR mutations were younger (p = 0.045) and had higher platelet counts (p = 0.043). CONCLUSION Genotyping for CALR could be a useful diagnostic tool for JAK2/MPL-negative ET, since the data suggest that CALR is much more prevalent than MPL, therefore testing for CALR should be considered in patients who are JAK2 negative as its frequency is almost 20 times that of MPL mutation.
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Lin CHS, Kaushansky K, Zhan H. JAK2 V617F-mutant vascular niche contributes to JAK2 V617F clonal expansion in myeloproliferative neoplasms. Blood Cells Mol Dis 2016; 62:42-48. [PMID: 27865175 DOI: 10.1016/j.bcmd.2016.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 09/19/2016] [Accepted: 09/24/2016] [Indexed: 12/13/2022]
Abstract
The myeloproliferative neoplasms (MPNs) are characterized by hematopoietic stem/progenitor cell (HSPC) expansion and overproduction of blood cells. The acquired mutation JAK2V617F plays a central role in these disorders. Mechanisms responsible for MPN HSPC expansion is not fully understood, limiting the effectiveness of current treatments. Endothelial cells (ECs) carrying the JAK2V617F mutation can be detected in patients with MPNs, suggesting that ECs are involved in the pathogenesis of MPNs. Here we report that JAK2V617F-bearing primary murine ECs have increased cell proliferation and angiogenesis in vitro compared to JAK2WT ECs. While there was no difference between JAK2V617F and JAK2WT HSPC proliferation when co-cultured with JAK2WT EC, the JAK2V617F HSPC displayed a relative growth advantage over the JAK2WT HSPC when co-cultured on JAK2V617F EC. In addition, the thrombopoietin (TPO) receptor MPL is up regulated in JAK2V617F ECs and contributes to the maintenance/expansion of the JAK2V617F clone over JAK2WT clone in vitro. Considering that ECs are an essential component of the hematopoietic niche and most HSPCs reside in the perivascular niche, our studies suggest that the JAK2V617F-bearing ECs form an important component of the MPN vascular niche and contribute to mutant stem/progenitor cell expansion, likely through a critical role of the TPO/MPL signaling axis.
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Smaili W, Doubaj Y, Laarabi FZ, Lyahyai J, Kerbout M, Mikdame M, Sefiani A. CALR gene mutational profile in myeloproliferative neoplasms with non-mutated JAK2 in Moroccan patients: A case series and germline in-frame deletion. Curr Res Transl Med 2016; 65:15-19. [PMID: 28340692 DOI: 10.1016/j.retram.2016.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/05/2016] [Indexed: 12/14/2022]
Abstract
BACKGROUND The discovery of somatic mutations within the gene encoding calreticulin (CALR) in 2013 represented a major milestone in the molecular diagnosis of BCR-ABL negative myeloproliferative neoplasms (MPN). In fact, exome sequencing revealed that most patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF) lacking JAK2 or MPL mutations, harbor somatic insertion and/or deletion in exon 9 of CALR gene. In this study, we identified the first CALR gene mutational landscape in Moroccan patients with MPN nonmutated for the JAK2 gene. METHODS We performed Sanger sequencing of exon 9 of CALR gene in blood samples obtained from 33 Moroccan patients with ET or PMF non-mutated for JAK2. RESULTS Of the 33 patients analyzed, we detected eight distinct variants in 15 patients (45.4%); six indel mutations, five with type 1 recurrent 52bp deletion, four with type 2 recurrent 5bp insertion and one in frame deletion which was found to be a germline variant suggesting a very rare condition in MPN. CONCLUSION This is the first cohort reported in CALR gene mutation analysis in Morocco. Our results were concordant with studies reported up to date and very encouraging in promoting the molecular diagnosis of myeloproliferative neoplasms in Moroccan patients. Moreover, the presence of a germline in frame deletion in a symptomatic patient should undermine the effectiveness of sizing assays without DNA sequencing in the diagnosis of CALR mutations.
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Senkevitch E, Durum S. The promise of Janus kinase inhibitors in the treatment of hematological malignancies. Cytokine 2016; 98:33-41. [PMID: 28277287 DOI: 10.1016/j.cyto.2016.10.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 10/20/2016] [Indexed: 01/12/2023]
Abstract
The Janus kinases (JAK) are a family of kinases that play an essential role in cytokine signaling and are implicated in the pathogenesis of autoimmune diseases and hematological malignancies. As a result, the JAKs have become attractive therapeutic targets. The discovery of a JAK2 point mutation (JAK2 V617F) as the main cause of polycythemia vera lead to the development and FDA approval of a JAK1/2 inhibitor, ruxolitinib, in 2011. This review focuses on the various JAK and associated components aberrations implicated in myeloproliferative neoplasms, leukemias, and lymphomas. In addition to ruxolitinib, other JAK inhibitors are currently being evaluated in clinical trials for treating hematological malignancies. The use of JAK inhibitors alone or in combination therapy should be considered as a way to deliver targeted therapy to patients.
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Ngo A, Koay AZ, Pecquet C, Diaconu CC, Ould-Amer Y, Huang Q, Kang C, Poulsen A, Lee MA, Jenkins D, Shiau A, Constantinescu SN, Choong ML. A Phenotypic Screen for Small-Molecule Inhibitors of Constitutively Active Mutant Thrombopoietin Receptor Implicated in Myeloproliferative Neoplasms. Comb Chem High Throughput Screen 2016; 19:824-833. [PMID: 27748177 DOI: 10.2174/1386207319666161010163825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/20/2016] [Accepted: 09/29/2016] [Indexed: 11/22/2022]
Abstract
BACKGROUND Rather than a Janus Kinase 2 inhibitor (ruxolitinib), a specific thrombopoietin receptor (TpoR) inhibitor would be more specific for the treatment of myeloproliferative neoplasms due to TpoR mutations. OBJECTIVE A cell-based phenotypic approach to identify specific TpoR inhibitors was implemented and a library of 505,483 small molecules was screened for inhibitory effects on cells transformed by TpoR mutants. RESULTS Among the identified hits are two analogs of 3-(4-piperidinyl) indole. The analogs showed about five-fold preferential inhibition of cell viability towards Ba/F3 cells expressing the TpoR W515L mutation compared to the parental cells. There was no significant difference in inhibition of cell viability between the TpoR wild type and the TpoR W515L mutant cells. Preferential inhibition of viability was observed in Ba/F3 cells expressing erythropoietin receptor (EpoR) when stimulated with Epo compared to stimulation with interleukin-3 (IL3). The indole analog inhibited ex vivo colony formations of primary bone marrow cells from heterozygous JAK2 V617F knock-in mice. Drug combination treatment study was performed using ruxolitinib and the indole analog. Drug synergistic effects were observed when cells were stimulated to proliferate through both the IL3 and TpoR pathways. Our compound specifically targets monoamine receptors in the rhodopsin-like receptor family of G protein-coupled receptor. CONCLUSION This screen has identified a monoamine receptor inhibitor that can inhibit viability of cells with active TpoR or EpoR signalings. Drug synergism with ruxolitib is demonstrated.
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Busque L, Porwit A, Day R, Olney HJ, Leber B, Éthier V, Sirhan S, Foltz L, Prchal J, Kamel-Reid S, Karsan A, Gupta V. Laboratory Investigation of Myeloproliferative Neoplasms (MPNs): Recommendations of the Canadian Mpn Group. Am J Clin Pathol 2016; 146:408-22. [PMID: 27686169 DOI: 10.1093/ajcp/aqw131] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
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.
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Matsumoto N, Mori S, Hasegawa H, Sasaki D, Mori H, Tsuruda K, Imanishi D, Imaizumi Y, Hata T, Kaku N, Kosai K, Uno N, Miyazaki Y, Yanagihara K. Simultaneous screening for JAK2 and calreticulin gene mutations in myeloproliferative neoplasms with high resolution melting. Clin Chim Acta 2016; 462:166-173. [PMID: 27693531 DOI: 10.1016/j.cca.2016.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/25/2016] [Accepted: 09/27/2016] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Recently, novel calreticulin (CALR) mutations were discovered in Janus kinase 2 (JAK2) non-mutated myelofibrosis (PMF) and essential thrombocythemia (ET) cases, with a frequency of 60-80%. We examined clinical correlations and CALR mutation frequency in our myeloproliferative neoplasms (MPN) cases, and introduce an effective test method for use in clinical practice. METHODS We examined 177 samples previously investigated for the JAK2 mutation for differential diagnosis of MPN. JAK2 and CALR mutations were analyzed using melting curve analysis and microchip electrophoresis, respectively. Next, we constructed a test for simultaneous screening of the JAK2 and CALR mutations utilizing high resolution melting (HRM). RESULTS Among 99 MPN cases, 60 possessed the JAK2 mutation alone. Of the 39 MPN cases without the JAK2 mutation, 14 were positive for the CALR mutation, all of which were ET. Using our novel screening test for the JAK2 and CALR mutations by HRM, the concordance rate of conventional analysis with HRM was 96% for the JAK2 mutation and 95% for the CALR mutation. CONCLUSION Our novel simultaneous screening test for the JAK2 and CALR gene mutations with HRM is useful for diagnosis of MPN.
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Kovacsovics-Bankowski M, Kelley TW, Efimova O, Kim SJ, Wilson A, Swierczek S, Prchal J. Changes in peripheral blood lymphocytes in polycythemia vera and essential thrombocythemia patients treated with pegylated-interferon alpha and correlation with JAK2V617F allelic burden. Exp Hematol Oncol 2016; 5:28. [PMID: 27708986 PMCID: PMC5037882 DOI: 10.1186/s40164-016-0057-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 09/17/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Pegylated-interferon alpha (PegINFα) treatment of patients with polycythemia vera (PV) and essential thrombocythemia (ET) has resulted in long-term clinical response, decreased JAK2V617F allelic burden and restoration of polyclonal hematopoiesis. The mechanisms of the beneficial effects of PegINFα are not clear, but available evidence suggests direct suppression of JAK2-mutated clone, induction of dormant stem cells to proliferation, and augmentation of an immune effect against PV and ET clones. METHODS We analyzed the phenotype and frequency of peripheral blood lymphocytes (PBL) from PegINFα treated patients and compared them to patients treated with hydroxyurea (HU). Samples collected at various time points before and during treatment were analyzed using multicolor flow cytometry. RESULTS We found that PegINFα increased the frequency of peripheral blood CD4+ Foxp3+ regulatory T cells (Treg). Highly suppressive Treg, characterized by co-expression of CD39 and HLA-DR, were also increased in PBL from PegINFα treated patients. We observed an augmentation of cycling CD8+ T cells, NK cells, and of poorly activated CD38+CD8+ T cells. Our results also suggest that PegINFα increased the frequency of PD-1+ CD4+ helper cells and PD-1+ CD4+ Foxp3+ Treg cells. None of these changes were present in HU treated patients. We analyzed the correlation between changes in different T cell populations in the peripheral blood with the changes in JAK2V617F allelic burden in clonal granulocytes. Augmentation of Ki-67+ Treg, HLA-DR+ CD39+ Treg, Helios+ Treg and HLA-DR+ CD38+ CD8+ T cells correlated with an increase in JAK2V617F allelic burden. We also found a positive correlation between PD-1+ Treg and JAK2V617F allelic burden; however, the number of available patients was small (n = 7). CONCLUSIONS We report marked changes in frequencies of PBL subsets after PegINFα treatment, suggesting an immunomodulatory effect by PegINFα. Generation of a more suppressive immune response, as measured by an increase in highly suppressive Treg and poorly activated CD8+ T cells, correlated with a poor molecular response. In this study, we have not identified changes in the PBL that would indicate the presence of an effective anti-tumor response.Trial registration NCT01259856, December 7. 2010 and NCT01259817, December 6. 2010, Grant #1P01CA108671-O1A2, July 17. 2006, Sponsor: MPDRC/NIH, NCI-2012-00269, January 12. 2011 and NCI-2012-00268, January 12. 2011.
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Cahu X, Constantinescu SN. Oncogenic Drivers in Myeloproliferative Neoplasms: From JAK2 to Calreticulin Mutations. Curr Hematol Malig Rep 2016; 10:335-43. [PMID: 26370832 DOI: 10.1007/s11899-015-0278-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During the past 10 years, major progress has been accomplished with the discovery of activating mutations that are associated with the vast majority of BCR-ABL negative human myeloproliferative neoplasms (MPNs). The identification in 2005 of JAK2 V617F triggered great interest in the JAK2-STAT5/STAT3 pathway. Discovery in 2006 of mutants of thrombopoietin receptor (TPO-R/MPL) and later on of mutants in negative regulators of JAK-STAT pathway led to the notion that persistent JAK2 activation is a hallmark of MPNs. In 2013, mutations in the gene coding for the chaperone calreticulin were reported in 20-30% of essential thrombocythemia and primary myelofibrosis patients. Here, we will address the question: what do we know about calreticulin that could help us understand its role in MPNs? In addition to oncogenic driver mutations, certain MPNs also exhibit epigenetic mutations. Targeting of both oncogenic drivers and epigenetic defects could be required for effective therapy.
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272
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Pai SG, Kaplan JB, Giles FJ. Long-acting interferon for myeloproliferative neoplasms - an update. Expert Rev Hematol 2016; 9:915-7. [PMID: 27584865 DOI: 10.1080/17474086.2016.1231571] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Buetow L, Tria G, Ahmed SF, Hock A, Dou H, Sibbet GJ, Svergun DI, Huang DT. Casitas B-lineage lymphoma linker helix mutations found in myeloproliferative neoplasms affect conformation. BMC Biol 2016; 14:76. [PMID: 27609087 PMCID: PMC5015263 DOI: 10.1186/s12915-016-0298-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/12/2016] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Casitas B-lineage lymphoma (Cbl or c-Cbl) is a RING ubiquitin ligase that negatively regulates protein tyrosine kinase (PTK) signalling. Phosphorylation of a conserved residue (Tyr371) on the linker helix region (LHR) between the substrate-binding and RING domains is required to ubiquitinate PTKs, thereby flagging them for degradation. This conserved Tyr is a mutational hotspot in myeloproliferative neoplasms. Previous studies have revealed that select point mutations in Tyr371 can potentiate transformation in cells and mice but not all possible mutations do so. To trigger oncogenic potential, Cbl Tyr371 mutants must perturb the LHR-substrate-binding domain interaction and eliminate PTK ubiquitination. Although structures of native and pTyr371-Cbl are available, they do not reveal how Tyr371 mutations affect Cbl's conformation. Here, we investigate how Tyr371 mutations affect Cbl's conformation in solution and how this relates to Cbl's ability to potentiate transformation in cells. RESULTS To explore how Tyr371 mutations affect Cbl's properties, we used surface plasmon resonance to measure Cbl mutant binding affinities for E2 conjugated with ubiquitin (E2-Ub), small angle X-ray scattering studies to investigate Cbl mutant conformation in solution and focus formation assays to assay Cbl mutant transformation potential in cells. Cbl Tyr371 mutants enhance E2-Ub binding and cause Cbl to adopt extended conformations in solution. LHR flexibility, RING domain accessibility and transformation potential are associated with the extent of LHR-substrate-binding domain perturbation affected by the chemical nature of the mutation. More disruptive mutants like Cbl Y371D or Y371S are more extended and the RING domain is more accessible, whereas Cbl Y371F mimics native Cbl in solution. Correspondingly, the only Tyr371 mutants that potentiate transformation in cells are those that perturb the LHR-substrate-binding domain interaction. CONCLUSIONS c-Cbl's LHR mutations are only oncogenic when they disrupt the native state and fail to ubiquitinate PTKs. These findings provide new insights into how LHR mutations deregulate c-Cbl.
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Xu Q, Liu GM, Wang FY, Zhang LJ, Liang WT, Cheng ZY. [The Effect of Ruxolitinib on the Expression of VEGF and HIF-1α in Leukemia HEL Cells]. SICHUAN DA XUE XUE BAO. YI XUE BAN = JOURNAL OF SICHUAN UNIVERSITY. MEDICAL SCIENCE EDITION 2016; 47:669-673. [PMID: 28598077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
OBJECTIVES To investigate the effect of Ruxolitinib on the expression of vascular endothelial growth factor (VEGF) and hypoxia inducible factor-1 α (HIF-1α) in HEL cells. METHODS he HEL cells were treated with Ruxolitinib in different concentrations (1 nmol/L, 5 nmol/L, 10 nmol/L, 50 nmol/L, 100 nmol/L, 500 nmol/L). The growth inhibition of Ruxolitinib on HEL cells was detected by CCK-8 assay;the mRNA expression level ofJAK2 were measured by RT-PCR and the protein level of p-JAK2, VEGF, HIF-1α were observed by Western blot after treated with Ruxolitinib for 24,48,72 h. Chick chorioallantoic membrane (CAM) test was used to testify the effect of Ruxolitinib on angiogenesis. RESULTS Ruxolitinib with different concentrations could inhibit HEL cells proliferation. RT-PCR showed that the mRNA level ofJAK2 decreased in a concentration-dependent manner and Western blot demonstrated that the expression levels of p-JAK2, VEGF and HIF-1α were lower in Ruxolitinib treatment groups than those in control group (P<0.05) after HEL cells were treated with different concentrations of Ruxolitinib for 24,48,72 h. Ruxolitinib significantly suppressed blood vessels'formation in CAM. CONCLUSIONS Ruxolitinib can inhibit VEGF, HIF-1α expression and angiogenesis of HEL leukemia cells by inhibiting JAK2 pathway.
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Aruch D, Schwartz M, Mascarenhas J, Kremyanskaya M, Newsom C, Hoffman R. Continued Role of Splenectomy in the Management of Patients With Myelofibrosis. CLINICAL LYMPHOMA, MYELOMA & LEUKEMIA 2016; 16:e133-e137. [PMID: 27373368 DOI: 10.1016/j.clml.2016.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/13/2016] [Accepted: 06/01/2016] [Indexed: 11/30/2022]
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