scholarly journals Prevalence and prognostic impact of allelic imbalances associated with leukemic transformation of Philadelphia chromosome–negative myeloproliferative neoplasms

Blood ◽  
2010 ◽  
Vol 115 (14) ◽  
pp. 2882-2890 ◽  
Author(s):  
Nils H. Thoennissen ◽  
Utz O. Krug ◽  
Dhong Hyun Tony Lee ◽  
Norihiko Kawamata ◽  
Gabriela B. Iwanski ◽  
...  
Keyword(s):  
Target Genes ◽  
Chromosomal Abnormalities ◽  
Myeloproliferative Neoplasms ◽  
Neutral Loss ◽  
Philadelphia Chromosome ◽  
Snp Array ◽  
Chronic Phase ◽  
Prognostic Impact ◽  
Leukemic Transformation ◽  
Blast Phase

Abstract Philadelphia chromosome–negative myeloproliferative neoplasms (MPNs) including polycythemia vera, essential thrombocythemia, and primary myelofibrosis show an inherent tendency for transformation into leukemia (MPN-blast phase), which is hypothesized to be accompanied by acquisition of additional genomic lesions. We, therefore, examined chromosomal abnormalities by high-resolution single nucleotide polymorphism (SNP) array in 88 MPN patients, as well as 71 cases with MPN-blast phase, and correlated these findings with their clinical parameters. Frequent genomic alterations were found in MPN after leukemic transformation with up to 3-fold more genomic changes per sample compared with samples in chronic phase (P < .001). We identified commonly altered regions involved in disease progression including not only established targets (ETV6, TP53, and RUNX1) but also new candidate genes on 7q, 16q, 19p, and 21q. Moreover, trisomy 8 or amplification of 8q24 (MYC) was almost exclusively detected in JAK2V617F− cases with MPN-blast phase. Remarkably, copy number–neutral loss of heterozygosity (CNN-LOH) on either 7q or 9p including homozygous JAK2V617F was related to decreased survival after leukemic transformation (P = .01 and P = .016, respectively). Our high-density SNP-array analysis of MPN genomes in the chronic compared with leukemic stage identified novel target genes and provided prognostic insights associated with the evolution to leukemia.

Prevalence and Prognostic Impact of Allelic Imbalances Associated with Leukemic Transformation of Philadelphia Chromosome-Negative Myeloproliferative Neoplasms.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1280-1280
Author(s):  
Nils Heinrich Thoennissen ◽  
Utz O. Krug ◽  
Dhong Hyun Lee ◽  
Norohiko Kawamata ◽  
Terra L Lasho ◽  
...  
Keyword(s):  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Snp Array ◽  
Chronic Phase ◽  
Prognostic Impact ◽  
Genomic Alterations ◽  
Leukemic Transformation ◽  
Blast Phase ◽  
Hematopoietic Stem

Abstract Abstract 1280 Poster Board I-302 Philadelphia-chromosome negative myeloproliferative neoplasms (MPNs) including polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF) are defined as clonal hematopoietic stem cell disorders. These disorders show an inherent tendency for transformation into leukemia (MPN-blast phase) which is hypothesized to be accompanied by acquisition of additional genomic lesions. We, therefore, obtained a comprehensive profile of genomic alterations associated with leukemic transformation by using single-nucleotide polymorphism (SNP) array in 88 MPN patients, as well as 71 cases with MPN-blast phase, and correlated these findings with their clinical parameters. A relatively high number of genomic alterations was found in MPN after leukemic transformation with 4.6 ± 0.6 abnormalities per sample compared to only 1.4 ± 0.2 changes per patient in chronic phase (p<0.001). Compared to the cytogenetic data, SNP-chip analysis detected about 47% additional chromosomal changes in the MPN samples, and 31% more in the MPN-blast phase cases, whereas SNP-array allelokaryotyping practically captured all cytogenetic abnormalities in our study population. Several additionally altered regions were detected in patients with MPN-blast phase compared to chronic phase, including both deletion and copy-number neutral-loss of heterozygosity (CNN-LOH) on chromosome 12p (9%) and 21q (9%), involving ETV6 and RUNX1. Notably, deletion and CNN-LOH on 17p involving TP53 were diagnosed in 18% of MPN-blast phase samples, which was highly associated with preceding treatment with alkylating agents (p=0.016). Moreover, trisomy 8, as well as amplification of 8q24.21 involving the MYC gene, were detected in 13% of patients with MPN-blast phase who were almost exclusively negative for the JAK2V617F mutation. Genome-wide inspection of further critical regions with promising new candidate genes involved in the evolution to the MPN-leukemic phase included deletion and CNN-LOH on 7q22.1 (SH2B2) in 18%, duplication/amplification on 19p13.2 (PIN1, ICAM1, CDC37) in 13% and 21q22.2 (ERG) in 9% of MPN patients with blast crisis. In contrast, we detected a decreased frequency of JAK2V617F in MPN-blast phase samples (52%) compared to chronic phase (71%). Also, the percentage of patients with homozygous mutant JAK2 as a result of CNN-LOH was lower in the MPN-blast phase (43%) compared to the chronic phase (53%). Taken together, the data suggest that gain-of-function mutation of JAK2 is not a perquisite for leukemic transformation. Remarkably, CNN-LOH on either 7q or 9p was related to decreased survival after leukemic transformation (p=0.02 and p=0.012, respectively). Given the variety of allelic imbalances, our data suggest that MPN-blast phase appears to be a heterogeneous disease prone to have evolved multiple mechanisms to provide a proliferative advantage to the abnormal leukemic clone. Our analysis of MPN genomes in the chronic compared to the leukemic stage provided new prognostic insights, as well as novel causative genes which might be involved in the transformation to MPN-blast phase. Disclosures No relevant conflicts of interest to declare.

Leukaemic Transformation of Philadelphia-chromosome-negative Myeloproliferative Neoplasms — A Review of the Molecular Background

2011 ◽  
Vol 07 (01) ◽  
pp. 59
Author(s):  
Nils H Thoennissen ◽  
H Phillip Koeffler ◽  
◽  
Keyword(s):  
Chromosomal Abnormalities ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Chronic Phase ◽  
Myeloid Cell ◽  
Primary Myelofibrosis ◽  
Haematopoietic Stem Cell ◽  
Polycythaemia Vera ◽  
Causative Role ◽  
Blast Phase

Philadelphia-chromosome-negative myeloproliferative neoplasms (MPNs), including polycythaemia vera (PV), primary myelofibrosis (PMF) and essential thrombocythaemia (ET), are clonal haematopoietic stem cell disorders characterised by proliferation of one or more myeloid cell lineages. They are closely associated with theJAK2V617F mutation, whose detection is used as a clonal marker in the differential diagnosis of MPN. Despite recent improvements in the molecular diagnosis and therapeutic regimen of these chronic disorders, haematological evolution to blast phase remains a major cause of long-term mortality. The mechanism of MPN transformation is still a matter of some controversy because of insufficient insights into the underlying molecular pathogenesis. The purpose of this article is to summarise the increasing data concerning the mechanism of leukaemic evolution of patients diagnosed with chronic MPN. Chromosomal abnormalities and genes that have been shown to play a potential causative role in chronic-phase acceleration are discussed, as are aberrations that may serve as prognostic markers in the blast phase of MPN.

scholarly journals Large Genomic Alterations Occurring in the Transition from Chronic to Blast Phase of Chronic Myeloproliferative Neoplasms

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3028-3028
Author(s):  
Niccolò Bartalucci ◽  
Alberto Magi ◽  
Elisa Contini ◽  
Davide Bolognini ◽  
Simone Romagnoli ◽  
...  
Keyword(s):  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Gc Content ◽  
Chronic Phase ◽  
Copy Number Variations ◽  
Chromosome 8 ◽  
Leukemic Transformation ◽  
Blast Phase ◽  
Paired Samples ◽  
The Mean

Abstract INTRODUCTION Five to 20% of patients with myeloproliferative neoplasms (MPN), including Essential Thrombocythemia (ET), Polycythemia Vera (PV) and Primary Myelofibrosis (PMF), transform to an aggressive secondary acute myeloid leukemia (sAML). While several studies reported the association of some mutations with the risk of leukemic transformation (Vannucchi AM et al, Leukemia 2013), the mechanisms that contribute to transformation from MPN to sAML remain largely poor characterized. METHODS. We collected annotated samples from 15 chronic-phase (CP) MPN patients (pts), 6 pts with accelerated phase (AP; PB blasts 10-19%) and 12 pts with sAML; for the latter, paired samples (chronic/blast phase-BP) were available. CP and BP samples were separated by a mean of 77 (12 to 216) months interval. We used Illumina whole exome sequencing (WES) to identify copy number variations (CNV) in all samples. In the paired samples set, we also performed long reads genome sequencing by the Oxford Nanopore technology, a uniform process that generates sequences randomly and independently, without classical sources of bias such as GC-content and mappability. Data analysis for CNV detection was performed by a novel devised computational package (Nano-GLADIATOR; Magi A, Bartalucci N et al, Genome Biology, submitted) allowing the analysis of individual samples without the need of paired-analysis. RESULTS. The mean number of CNV detected in CP, AP and BP samples was respectively 130.7±49, 132±42 and 177.4±61 (P=0.03 of BP vs CP). CNV were represented by gain of genomic material in 63.6%, 68.2% and 64.1% of CP, AP and BP. Considering the length of all CNV, expressed as base pairs (bp), we found that 96.8% of CNV in CP were focal alterations spanning <1 Mega bases (Mb) while only 2.9% and 0.3% were larger than 1Mb and 30Mb, respectively. Conversely, alterations involving >1Mb and >30Mb in BP samples were 14.4% (P=0.05) and 2.1% (P=0.04), and corresponding figures in AP were respectively 5.3% (ns vs CP, P=0.05 vs BP) and 0.7% (P=0.04 vs CP). Considering CNV >1Mb only, 53.7% were gains in CP compared with 68.1% in AP and 63.6% in BP, while losses were 46.3%, 31.9% and 36.4% respectively. Furthermore, alterations involving all the short (p) and long (q) -arm or the whole chromosome were found in 77% of BP compared to 36% of AP and 11% only of CP samples (P<0.01), overall indicating that larger alterations are enriched in BP. We used Nanopore platform to analyze paired CP and BP samples. We found that the total number of bp involved in CNV was 380x106 and 2x109 in CP and BP, respectively, with an estimated frequency of 0.01 and 0.07 altered base every 1 base of normal genome. The mean length of CNV was 5.6x106 bp and 23.7x106 bp respectively in CP and BP samples. There was a total of 29 new CNV acquired in BP samples compared to CP, involving 10 different chromosomes. We identified recurrent alterations as double or single deletion of 100,000 bp in chromosome 8 (55.5% of BP), deletion of a 510.000 to 610.000 bp region of chromosome 4q (40% of BP) and an amplification of 32,535,000 bp in chromosome 21q in 34% of BP samples. Alterations involving chromosomes 4 and 8 detected in BP samples were already present at paired CP samples in 75% and 80% of cases, while in the remaining 25% and 20% they were acquired at BP. The same abnormalities were absent from the 15 unpaired CP samples (WES data) whereas they were present in 4/6 and 3/6 of AP patients, respectively. CONCLUSION All together, this data indicate that genomic instability is a hallmark of leukemic transformation of MPN and for the first time identify regions that may be recurrently associated with disease progression from CP to BP, potentially representing novel biomarkers. These finding require confirmation in larger series. Disclosures No relevant conflicts of interest to declare.

Genome integrity of myeloproliferative neoplasms in chronic phase and during disease progression

Blood ◽  
2011 ◽  
Vol 118 (1) ◽  
pp. 167-176 ◽  
Author(s):  
Thorsten Klampfl ◽  
Ashot Harutyunyan ◽  
Tiina Berg ◽  
Bettina Gisslinger ◽  
Martin Schalling ◽  
...  
Keyword(s):  
Disease Progression ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Chronic Phase ◽  
Phase Changes ◽  
Janus Kinase ◽  
Leukemic Transformation ◽  
New Genes ◽  
Mutational Status ◽  
Secondary Myelofibrosis

Abstract Philadelphia chromosome–negative myeloproliferative neoplasms (MPNs) are clonal myeloid disorders with increased production of terminally differentiated cells. The disease course is generally chronic, but some patients show disease progression (secondary myelofibrosis or accelerated phase) and/or leukemic transformation. We investigated chromosomal aberrations in 408 MPN samples using high-resolution single-nucleotide polymorphism microarrays to identify disease-associated somatic lesions. Of 408 samples, 37.5% had a wild-type karyotype and 62.5% harbored at least 1 chromosomal aberration. We identified 25 recurrent aberrations that were found in 3 or more samples. An increased number of chromosomal lesions was significantly associated with patient age, as well as with disease progression and leukemic transformation, but no association was observed with MPN subtypes, Janus kinase 2 (JAK2) mutational status, or disease duration. Aberrations of chromosomes 1q and 9p were positively associated with disease progression to secondary myelofibrosis or accelerated phase. Changes of chromosomes 1q, 7q, 5q, 6p, 7p, 19q, 22q, and 3q were positively associated with post-MPN acute myeloid leukemia. We mapped commonly affected regions to single target genes on chromosomes 3p (forkhead box P1 [FOXP1]), 4q (tet oncogene family member 2 [TET2]), 7p (IKAROS family zinc finger 1 [IKZF1]), 7q (cut-like homeobox 1 [CUX1]), 12p (ets variant 6 [ETV6]), and 21q (runt-related transcription factor 1 [RUNX1]). Our data provide insight into the genetic complexity of MPNs and implicate new genes involved in disease progression.

scholarly journals The Importance of Identification of M-BCRABL Oncogene and JAK2V617F Mutation in Myeloproliferative Neoplasms

2014 ◽  
Vol 60 (2) ◽  
pp. 44-48
Author(s):  
Annamária Szántó ◽  
Zsuzsanna Pap ◽  
Z Pávai ◽  
I Benedek ◽  
Judit Beáta Köpeczi ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Molecular Biology ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Gene Mutations ◽  
Chronic Phase ◽  
Final Diagnosis ◽  
Jak2v617f Mutation ◽  
Myeloproliferative Disease

Abstract Background: The elucidation of the genetic background of the myeloproliferative neoplasms completely changed the management of these disorders: the presence of the Philadelphia chromosome and/or the BCR-ABL oncogene is pathognomonic for chronic myeloid leukemia and identification of JAK2 gene mutations are useful in polycytemia vera (PV), essential thrombocytemia (ET) and myelofibrosis (PMF). The aim of this study was to investigate the role of molecular biology tests in the management of myeloproliferative neoplasms. Materials and methods: We tested the blood samples of 117 patients between April 2008 and February 2013 at the Molecular Biology of UMF Târgu Mureș using RQ-PCR (for M-BCR-ABL oncogene) and/or allele-specific PCR (for JAK2V617F mutation). Results: Thirty-two patients presented the M-BCR-ABL oncogene, 16 of them were regularly tested as a follow-up of the administered therapy: the majority of chronic phase patients presented decreasing or stable values, while in case of accelerated phase and blast phase the M-BCR-ABL values increased or remained at the same level. Twenty patients were identified with the JAK2V617F mutation: 8 patients with PV, 4 with ET, 3 with PMF, 4 with unclassifiable chronic myeloproliferative disease and 1 patient with chronic myelomonocytic leukemia. There was no case of concomitant occurance of both molecular markers. Conclusions: Molecular biology testing plays an important role in the management of myeloproliferative neoplasms: identification of the molecular markers confirms the final diagnosis, excluding secondary causes of abnormal blood count parameters. Regular monitoring of MBCR- ABL expression level is useful in the follow-up of therapeutic efficiency.

scholarly journals Association of a chromosomal 3;21 translocation with the blast phase of chronic myelogenous leukemia

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1338-1342 ◽  
Author(s):  
CM Rubin ◽  
RA Larson ◽  
MA Bitter ◽  
JJ Carrino ◽  
MM Le Beau ◽  
...  
Keyword(s):  
Chronic Myelogenous Leukemia ◽  
Reciprocal Translocation ◽  
Clonal Evolution ◽  
Philadelphia Chromosome ◽  
Chronic Phase ◽  
Myelogenous Leukemia ◽  
Cytogenetic Abnormality ◽  
Blast Phase ◽  
Male Patients

Abstract An identical reciprocal translocation between the long arms of chromosomes 3 and 21 with breakpoints in bands 3q26 and 21q22, t(3;21)(q26;q22), was found in three male patients with the blast phase of chronic myelogenous leukemia (CML). The abnormality was clonal in all three patients and was always accompanied by either a standard or variant 9;22 translocation resulting in a Philadelphia chromosome (Ph1). In two cases, the t(3;21) was the only abnormality other than a t(9;22) in the primary clone. Serial studies of one patient demonstrated that the t(3;21) occurred as a result of clonal evolution near the time of development of the blast phase. We have not observed the t(3;21) in greater than 500 patients with CML in the chronic phase. Thus, the t(3;21) is a new recurring cytogenetic abnormality associated with the blast phase of CML.

scholarly journals Loss of heterozygosity 4q24 and TET2 mutations associated with myelodysplastic/myeloproliferative neoplasms

Blood ◽  
2009 ◽  
Vol 113 (25) ◽  
pp. 6403-6410 ◽  
Author(s):  
Anna M. Jankowska ◽  
Hadrian Szpurka ◽  
Ramon V. Tiu ◽  
Hideki Makishima ◽  
Manuel Afable ◽  
...  
Keyword(s):  
Loss Of Heterozygosity ◽  
Chromosomal Abnormalities ◽  
Myeloproliferative Neoplasms ◽  
Neutral Loss ◽  
Regulatory Gene ◽  
Clinical Analysis ◽  
Gene Marker ◽  
Compound Heterozygous ◽  
Single Nucleotide ◽  
Myeloid Malignancies

Abstract Chromosomal abnormalities are frequent in myeloid malignancies, but in most cases of myelodysplasia (MDS) and myeloproliferative neoplasms (MPN), underlying pathogenic molecular lesions are unknown. We identified recurrent areas of somatic copy number–neutral loss of heterozygosity (LOH) and deletions of chromosome 4q24 in a large cohort of patients with myeloid malignancies including MDS and related mixed MDS/MPN syndromes using single nucleotide polymorphism arrays. We then investigated genes in the commonly affected area for mutations. When we sequenced TET2, we found homozygous and hemizygous mutations. Heterozygous and compound heterozygous mutations were found in patients with similar clinical phenotypes without LOH4q24. Clinical analysis showed most TET2 mutations were present in patients with MDS/MPN (58%), including CMML (6/17) or sAML (32%) evolved from MDS/MPN and typical MDS (10%), suggesting they may play a ubiquitous role in malignant evolution. TET2 mutations affected conserved domains and the N terminus. TET2 is widely expressed in hematopoietic cells but its function is unknown, and it lacks homology to other known genes. The frequency of mutations in this candidate myeloid regulatory gene suggests an important role in the pathogenesis of poor prognosis MDS/MPN and sAML and may act as a disease gene marker for these often cytogenetically normal disorders.

The Role of Dasatinib in Patients with Philadelphia (Ph) Positive Acute Lymphocytic Leukemia (ALL) and Chronic Myeloid Leukemia (CML) Relapsing after Stem Cell Transplantation (SCT).

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4520-4520 ◽  
Author(s):  
Ehab Atallah ◽  
Hagop Kantarjian ◽  
Marcos De Lima ◽  
Gautam Borthakur ◽  
William Wierda ◽  
...  
Keyword(s):  
Median Time ◽  
Liver Toxicity ◽  
Chromosomal Abnormalities ◽  
Chronic Phase ◽  
Cytogenetic Response ◽  
Lymphocytic Leukemia ◽  
High Dose ◽  
Polymorphism Analysis ◽  
Blast Phase ◽  
Treatment Interruptions

Abstract Patients (pts) with CML or Ph+ ALL relapsing after SCT have a poor prognosis and short survival. Dasatinib has shown significant efficacy in patients with Ph+ diseases after imatinib failure. We reviewed the outcome of patients who relapsed after allogeneic SCT and received dasatinib as salvage therapy. Eleven pts were treated (9 CML and 2 Ph+ ALL). The median age was 48 (15–67) and 9 were male. At the time of SCT, the two ALL pts were in CR, one in 1st CR (CR1) and one in 2nd CR (CR2). Of the CML pts, 4 were in chronic phase (CP), 2 in myeloid blast phase (MyBP), 2 in CR1 lymphoid blast phase (LyBP), and 1 in CR1 MyBP. Six pts received SCT from HLA-identical sibling donors and 5 had matched unrelated donors. Two pts had received a T-cell depleted graft and 1 pt had 3 allogeneic transplants prior to dasatinib therapy. The median time from SCT to relapse was 75 days (11–310 days) and median time from SCT to dasatinib was 267 (17 to 4408). All patients had failed prior high-dose imatinib therapy. Ten patients received imatinib prior to SCT and 4 pts achieved complete cytogenetic response (CCyR). At the time dasatinib was started, 5 CML pts were in MyBP, 2 in LyBP, 1 in accelerated phase (AP), and 1 in CP. Both ALL pts had relapsed disease. Ten pts were Ph+ in the bone marrow by cytogenetics (median 63% range 0% to 100%) and 9 had additional chromosomal abnormalities; 1 pt had diploid cytogenetics with detectable bcr/abl transcripts by RT-PCR. Bcr/Abl kinase domain mutations were investigated in 7 patients prior to dasatinib, and a mutation was identified in 4 (E3225G, E255G, G250E and F317L). The starting dose of dasatinib was 50 mg twice daily (BID) in 3 pts, 70 mg BID in 7 and 90mg once daily in one pt. Nine pts (82%) responded as follows: 3 pts achieved complete molecular remission (cMR), 1 CCyR, 2 a partial cytogenetic response (PCyR), 1 minor cytogenetic response (mCyR), 2 partial marrow response; and 2 pts had no response. Two pts had received nilontinib prior to dasatinib: 1 had a mCyR, and one CHR with no cytogenetic response. Three pts had PCR-based microsatellite polymorphism analysis performed after dasatinib therapy, and one pt had 100% donor myeloid and T cells. Two patients received nilontinib post dasatinib: 1 had no response with rapid disease progression and one achieved a CCyR but died of sepsis. All patients receiving dasatinib 70 mg PO BID had treatment interruptions or required dose reductions for gastrointestinal bleeding (3 patients), thrombocytopenia (3 patients), pulmonary complications (2 patients) and liver toxicity (one patient). In the 3 pts starting dasatinib at 50 mg PO BID, one had a dose escalation and the other two had short response durations and did not require dose modifications. At the time of this analysis, 6 pts have died, 3 are alive in cMR, and 2 are alive with disease. The three patients who achieved a cMR had relapsed ALL, CML in AP and MyBP and are alive 15, 17 and 18 months after start of dasatinib, respectively. The median overall survival from start of dasatinib was 381 days and median PFS was 118 days. In summary, despite the advanced stage of these patients at the start of therapy, these results show that dasatinib can induce durable complete remissions in patients with CML and Ph+ ALL who relapse after SCT with acceptable toxicity.

Genomic Changes Associated with Leukemic Transformation of Myeloproliferative Disorders.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3371-3371
Author(s):  
Nils Heinrich Thoennissen ◽  
Norihiko Kawamata ◽  
Terra L Lasho ◽  
Tamara Weiss ◽  
Daniel Nowak ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Chromosomal Abnormalities ◽  
Neutral Loss ◽  
Uniparental Disomy ◽  
Myeloproliferative Disorders ◽  
Lymphoid Cells ◽  
Leukemic Transformation ◽  
Altered Expression ◽  
Snp Chip ◽  
Genomic Changes

Abstract Myeloproliferative disorders (MPD) are a group of heterogeneous diseases that include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). They are characterized by increased hematopoiesis leading to elevated numbers of non-lymphoid cells and/or platelets in the peripheral blood. Beside thrombotic and hemorrhagic complications, MPD may evolve into secondary acute myeloid leukemia (sAML). Recently characterized markers suggest an opportunity to diagnose and identify subpopulations of MPD patients. In particular, altered expression and point mutations of PRV-1, MPL and JAK2 were commonly found in MPD, as well as deletions on chromosome 20q (del20q). Acquired uniparental disomy (UPD) on chromosome 1p (1pUPD) and 9p (9pUPD) leading to copy-neutral loss of heterozygosity (LOH) is a further mechanism found in MPD which often leads to homozygous activated mutations of MPL and JAK2, respectively. However, the molecular mechanisms involved in the transformation process to sAML remains unclear. Using standard metaphase cytogenetics (MC), chromosomal abnormalities are found in only a proportion of patients with MPD. We hypothesized that with new precise methods more genomic lesions can be uncovered that may be associated with leukemic transformation. To address this issue, we used 250K single nucleotide polymorphisms (SNP) Chip arrays to study chromosomal lesions in 40 sAML samples from patients who evolved from MPD; 7 had preexisting PV, 25 PMF, and 8 ET. Moreover, 43 additional samples of MPD (10 PV, 17 ET, and 16 PMF) were included in this study. SNP-chip analysis showed major chromosomal changes in almost all the sAML samples including monosomy 16, deletions of 1q-, 3p-, 6p-, 5q-, 7q-, 9q-, 12p-, 6q-, 3q-, 17p-, 19q-, and 20q- as well as trisomy 2, 3, 8, 9, 12, 15, 19, 21, and 22. We validated these data by MC. However, numerous new genomic alterations which contained potentially interesting genes that might contribute to leukemic transformation were detected by SNP Chip Array in patient samples with normal karyotype. Moreover, UPD was very frequent: 44% (19/43) of MPD and 53 % (21/40) sAML samples. 1pUPD occurred in 5 patients with MPD (1PV, 4 PMF; 12 %) compared to 5 patients with sAML (1 PV, 4 PMF; 13 %). 9pUPD was found in 16 MPD patients (8 PV, 7 PMF, 1 ET; 37%) and 6 sAML patients (3 PV, 2 PMF, 1ET; 15 %). All patients with 9pUPD proved to be positive for the JAK2 V617F mutation seen by allele specific PCR. Interestingly, the MPD samples only had UPD on 1p, 9p, and 12q. In contrast, sAML samples showed additional UPD regions on 7q, 11q, 12q, 16p, 17p, 19q, and 21q. Beside the evaluation of the non-matching groups of patients with MPD and sAML, we also evaluated 4 patients during their PMF and sAML stages by SNP Chip. The sAML samples acquired additional genomic changes including trisomy 8, 10, 14, 19, duplication on 3q and 6p, and heterozygote deletion on 18q. In contrast, 1pUPD, 9pUPD, and 12qUPD were detected in both MPD and sAML matching samples, suggesting that these changes do not play an immediate role in causing transformation. In conclusion, we detected chromosomal regions possessing genes which may be involved in the leukemic transformation of MPD patients.

CBL, CBLB, TET2, ASXL1, and IDH1/2 Mutations as Well as Additional Chromosomal Aberrations Constitute Molecular Events Contributing to Malignant Progression In Advanced Philadelphia Chromosome-Positive Disorders.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3396-3396
Author(s):  
Hideki Makishima ◽  
Anna Jankowska ◽  
Michael A McDevitt ◽  
Simon Dujardin ◽  
Heather Cazzolli ◽  
...  
Keyword(s):  
Clinical Features ◽  
Copy Number ◽  
Chromosomal Abnormalities ◽  
Philadelphia Chromosome ◽  
Chronic Phase ◽  
Kinase Domain ◽  
Chromosome 8 ◽  
Molecular Events ◽  
Advanced Phase ◽  
Imatinib Resistant

Abstract Abstract 3396 Chronic myeloid leukemia (CML) is characterized by the BCR/ABL fusion gene. However, secondary molecular events leading to accelerated (AP) or blast phase (BP) have not been sufficiently clarified. We hypothesized that, in analogy to other MDS/MPN or MPN, TET2, ASXL1, CBL and IDH family mutations may also occur in CML and contribute as secondary events leading to progression to AP or BP. Similarly, higher resolution of cytogenetic testing by single nucleotide polymorphism array (SNP-A)-based karyotyping may reveal additional chromosomal abnormalities associated with stepwise progression. This study is focused on the combined analysis of chromosomal lesions and mutations associated with AP, BP and Philadelphia chromosome (Ph) positive acute lymphoblastic leukemia (ALL) and the association of these defects with clinical features. We screened TET2, ASXL1, CBL and IDH for mutations in AP (N=14) and BP (N=26) and Ph+ ALL (N=9). Chronic phase (CP) (N=14) and Ph negative ALL (N=9) served as controls. We identified 3 CBL family (9%), 7 TET2 (21%), 2 ASXL1 (6%) and 2 IDH family (6%) mutations in patients with AP and myeloid BP. Subsequently, we also detected a TET2 mutation in a case of Ph+ ALL. None of these mutations were found in patients with CP or Ph negative ALL. We also performed SNP-A-based karyotyping and only included lesions which did not overlap with copy number variations (CNVs) or germ line regions of homozygosity present in any of the controls. 23 gains, 21 losses and 4 regions of somatic UPD lesions were identified. By SNP-A, additional copy number abnormalities, including microdeletions were found in 67% and 50% of patients with AP and BP, respectively. Recurrent lesions were detected on chromosome 1, 8, 9, 17 and 22. Microdeletions on chromosome 17 and 21 involved tumor associated genes NF1 and RUNX1. Deletions flanking the ABL1 and BCR genes were observed in 3 cases with der(22)t(9;22) or der(9)t(9;22) by metaphase cytogenetics. Gains including 1q25.3q41, chromosome 8 and 17q24.3 were found in 3 cases. Regions of UPD included UPD5q, 8q, 11p and 17q but no UPD involving 11q (CBL) and 4q (TET2) regions were found confirming heterozygous nature of the corresponding mutations. Newly detected molecular lesions associated with AP and BP may change the biology and thereby clinical features of affected cases. Overall survival of patients with mutations did not differ from those without mutations. Of note is that BCR/ABL1 kinase domain mutations were detected in 9/10 patients with imatinib resistance. In these 9 cases, 3 TET2 and 2 CBLB mutations were detected (but no mutations in the other genes). In an imatinib-resistant patient without BCR/ABL1 kinase domain mutation, CBL mutation was present. In the patients with TET2 mutations, additional chromosomal lesions were found by SNP-A, significantly more frequently when compared with WT cases (P=0.017). Of the 9 TET2 variants in 8 cases, 7 (78%) were missense substitutions, 1 (11%) was frame shift and 1 (11%) produced a stop codon and were located within the N-terminus as well as in a conserved DSBH 2OG-Fe(II)-dependent dioxygenase domain. The presence of nonsense and frameshift mutations suggests that mutated lesions result in inactivation, consistent with putative tumor suppressor functions, while heterozygous mutations indicate that the wild type allele is not completely protective. Since no TET2 mutations were identified in chronic phase CML, these mutations might represent an additional pathogenic event and contribute to progression. In 3 cases we observed a combination of 2 mutations. Coincidence of CBLB and TET2 mutations in 2 cases suggests that these might cooperate in the evolution of advanced phase of CML. We also found a combination of IDH1 and ASXL1 mutations in a patient with BP, suggesting that both mutations contribute to clonal advantage. In conclusion, while CBL family, ASXL1 and IDH family mutations as well a additional unbalanced chromosomal abnormalities not seen by metaphase cytogenetics can occur in myeloid type advanced phase CML, TET2 mutations were identified in Ph+ ALL, as well as myeloid BP and AP. These mutations likely represent secondary lesions which contribute to either disease progression or more aggressive features and commonly occur in association with imatinib-resistant BCR/ABL mutations. Disclosures: No relevant conflicts of interest to declare.

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