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.

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.

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.

IDH mutations in Primary Myelofibrosis Predict Leukemic Transformation and Shortened Survival: Clinical Evidence for Leukemogenic Collaboration with JAK2V617F

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1751-1751
Author(s):  
Nanna Sulai ◽  
Thitina Jimma ◽  
Terra L Lasho ◽  
Christy Finke ◽  
Ryan A Knudson ◽  
...  
Keyword(s):  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Univariate Analysis ◽  
Multivariable Analysis ◽  
Chronic Phase ◽  
Primary Myelofibrosis ◽  
Molecular Subgroups ◽  
Leukemic Transformation ◽  
Prognostic Relevance ◽  
Idh Mutations

Abstract Abstract 1751 Because IDH mutations are frequent in blast-phase myeloproliferative neoplasms (MPN), they might contribute to leukemic transformation. We examined this possibility in 301 consecutive patients with chronic-phase primary myelofibrosis (PMF). All study patients were fully characterized for karyotype, JAK2 and MPL mutational status, and Dynamic International Prognostic Scoring System-plus (DIPSS-plus) risk status. DNA from bone marrow or peripheral blood was used to screen for IDH1 and IDH2 mutations, by direct sequencing and/or high resolution melting (HRM) assay. Mutant IDH was detected in 12 patients (4%): seven IDH2 (five R140Q, one R140W and one R172G) and five IDH1 (three R132S and two R132C). MPL exon 10 was mutated in 18 patients (6.3%) and constituted W515L in 14 patients, W515K in 3 and a frameshift mutation in 1 patient. JAK2V617F was detected in 169 (56%) patients. Six patients displayed both JAK2V617F and IDH mutations (IDH2R140Q in 2 patients, IDH2R140W in 1 and IDH1R132S in 3); JAK2V617F allele burden was 1%, 7%, 22%, 27%, 30% and 96%, respectively. One patient displayed both IDHR140Q and MPLW515R. One-hundred and seven (36%) patients were negative for all three mutations. The 12 IDH-mutated patients were clinically compared to patients belonging to the three other molecular subgroups: mutated for JAK2 only (n=164), mutated for MPL only (n=18) and unmutated for all three (n=107). The four molecular subgroups were remarkably similar in their phenotype with few exceptions; IDH-mutated patients were significantly older than those with no mutations (p=0.04) whereas age distribution was similar between patients with mutant IDH, MPL or JAK2. In univariate analysis, overall survival (OS) for IDH-mutated patients was significantly shorter than those for JAK2-mutated (p=0.03), MPL-mutated (p=0.047) or unmutated (p=0.0009) patients. IDH-mutated patients also showed significantly shorter leukemia-free survival (LFS), compared to those with mutant JAK2 (p=0.0008), mutant MPL (p=0.02) or no mutations (p=0.001). After accounting for age, the presence of mutant IDH remained a significant disadvantage for both OS (p=0.04) and LFS (p=0.005). Multivariable analysis of OS that included risk categorization per DIPSS-plus confirmed the independent prognostic relevance of mutant IDH (p=0.03): HR for patients with no mutations =0.39, 95% CI 0.2–0.75; HR for JAK2-mutated patients =0.50, 95% CI 0.27–0.95; HR for MPL-mutated patients =0.53, 95% CI 0.23–1.2. A similar analysis for LFS that included risk factors for LT (i.e. unfavorable karyotype and platelet count <100 × 109/L) as covariates also confirmed the prognostic relevance of mutant IDH (p=0.003): HR for patients with no mutations =0.16; 95% CI 0.06–0.46; HR for JAK2-mutated patients =0.18; 95% CI 0.06–0.48; HR for MPL-mutated patients =0.09; 95% CI 0.01–0.76). Further analysis disclosed that the negative OS and LFS effect of mutant IDH was most pronounced in the presence (p=0.0002 and <0.0001, respectively) as opposed to the absence (p=0.34 and 0.64, respectively) of concomitant JAK2V617F expression. Analysis of paired samples obtained during the chronic and blast phases of the disease was possible in 2 IDH-mutated patients and showed the presence of both IDH and JAK2 mutations at both time points. Our observations suggest that IDH mutations in PMF are independent predictors of leukemic transformation and raise the possibility of leukemogenic collaboration with JAK2V617F. Disclosures: No relevant conflicts of interest to declare.

TET2 and ASXL1 Mutations in Leukemic Transformation of Chronic Myeloproliferative Neoplasms.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2894-2894 ◽  
Author(s):  
Omar Abdel-Wahab ◽  
Taghi Manshouri ◽  
Jay Patel ◽  
Kelly Harris ◽  
Jin Juan Yao ◽  
...  
Keyword(s):  
De Novo ◽  
Myeloproliferative Neoplasms ◽  
Myeloproliferative Neoplasm ◽  
Leukemic Transformation ◽  
Exact Test ◽  
Chronic Myeloproliferative Neoplasms ◽  
Secondary Acute Myeloid Leukemia ◽  
Paired Samples ◽  
Mutational Status ◽  
De Novo Aml

Abstract Abstract 2894 Poster Board II-870 Recent studies have identified TET2 and ASXL1 mutations in myeloid malignancies, suggesting that acquisition of these mutant alleles might precede the acquisition of JAK2 in some myeloproliferative neoplasm (MPN) patients. Moreover, the observation that JAK2 mutations are observed in minority of patients with leukemic transformation of JAK2-mutant MPNs suggests the possibility that JAK2 mutations are dispensable for leukemic transformation. However the role of TET2 and ASXL1 mutations in leukemic transformation has not been evaluated. We therefore investigated the mutational status of JAK2, TET2, and ASXL1 in 63 patients with leukemic transformation from a pre-existing MPN, including 49 unpaired secondary acute myeloid leukemia (sAML) samples and 14 patients for whom paired MPN and sAML samples were available. Mutations of TET2 and ASXL1 were found at a higher frequency in sAML samples transformed from MPNs than reported for sporadic MPNs (9/46 (19.6%) and 7/46 (15.2%), respectively). This was also higher than the mutational frequency of TET2 and ASXL1 in de novo AML (6.4% (3/47) and 4.3% (2/47), respectively) but similar to that of AML transformed from MDS (12.8% (5/39) and 15.4% (6/39)). All possible genetic combinations of JAK2, TET2, and ASXL1 status were observed in sAML patients. Analysis of paired samples reveal that TET2 mutations are far more likely to occur at leukemic transformation of MPN than at MPN diagnosis (p=0.013, Fisher's exact test) whereas ASXL1 mutations were equally likely to occur at MPN or sAML. Although mutations in JAK2 and in TET2 may not be retained at leukemic transformation from MPN, mutations in ASXL1 at MPN diagnosis were consistently retained at leukemic transformation. In addition, individual cases were observed where TET2 and/or ASXL1 mutations were found before acquisition of JAK2 mutations or clinical evidence of MPN, as well as cases where TET2 and ASXL1 mutations were acquired during leukemic transformation of a JAK2V617F-positive clone. These data suggest the mutational order of events in MPN and sAML pathogenesis might vary in different patients, and that TET2 and ASXL1 mutations might contribute in different patients to the development of MPN and/or to leukemic transformation. In addition, the identification of transformed AML cases with no evidence of pre-existing JAK2, TET2, and ASXL1 mutations indicates the existence of other, not yet identified, mutations necessary for leukemic transformation of MPNs. Disclosures: Levine: Novartis: Research Funding; TargeGen: Consultancy. Verstovsek:Incyte: ; Exelixis: ; Cephalon: ; SBIO: ; AstraZeneca: .

Mechanisms of Co-Operation of DNMT3A Mutations with JAK2 V617F Through Histone H4 Arginine 3 Provides New Insights in MPN Disease Pathogenesis

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2823-2823
Author(s):  
Nisha Rao ◽  
Carolyn M Butcher ◽  
Petra J Neufing ◽  
Sarah Bray ◽  
Chris N Hahn ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Somatic Mutations ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Chronic Phase ◽  
Site Directed Mutagenesis ◽  
Hek293 Cells ◽  
Histone H4 ◽  
Critical Residue

Abstract Abstract 2823 Myeloproliferative neoplasms (MPN), including Polycythemia vera (PV), Essential Thrombocythemia (ET) and Primary myelofibrosis (PMF), are clonal stem cell disorders characterised by an excess of mature cells of one or more myeloid lineages in the chronic phase, and an associated risk of progression to myelofibrosis and leukemic transformation. Highly specific somatic mutations of JAK2 and MPL are found in the majority of MPN patients, while numerous other somatic mutations have now been identified to be common between MPN and de novo acute myeloid leukemia (AML), including somatic mutations of TET2, ASXL1, CBL, IKZF1, EZH2, IDH1, IDH2 (reviewed in Tefferi, 2010 (Tefferi)), and most recently the DNA methyltransferase, DNMT3A (Abdel-Wahab, et al, Ley, et al, Stegelmann, et al, Walter, et al, Yan et al). We identified somatic heterozygous mutations in DNMT3A affecting amino acids R882 (R882C) and M880 (M880V), detected in peripheral blood mononuclear cells from two JAKV617F-positive PV patients (Rao et al, 2011, accepted for publication). At the level of chromatin and gene regulation, cooperation of DNMT3A mutations with JAK2V617F can occur through direct interaction of DNMT3A with the chromatin modifying protein PRMT5 which is a direct phosphorylation target of JAK2V617F (Liu F et al, 2011). PRMT5 is an arginine methyltransferase which associates with chromatin and methylates the key arginine (R) residue at the N-terminus of histone H4 (R3), which in turn recruits a DNMT3A complex resulting in methylation of adjacent CpG residues and gene-silencing (Zhao Q et al., 2009). To test the functional affects of DNMT3A mutations M880V and R882C, we have performed site- directed mutagenesis to generate GFP-tagged DNMT3A wild-type and mutant retroviral constructs. These DNMT3A clones will be transduced into cord blood CD34+ve cells and GFP-positive cells selected with flow cytometry. For functional analysis, we will examine DNA methyltransferase activity, changes in histone H4 modifications and CpG methylation. In a complementary analysis we have identified a change in a JAK2V617F+ve PV patient in the highly conserved HIST1H4C gene resulting in a substitution of Arg3 for Cys in Histone H4. Although there are 15 histone H4 genes encoding identical proteins, gene expression varies significantly in tissues and in cancer cells (W.F Holmes et. al, J.Biol Chem, 2005). We have used Q-PCR, using long primers to differentiate H4 transcripts and measured relative expression levels. We have confirmed that HIST1H4C is the major contributor of the H4 pool making ≥50% of the total H4 RNA in normal CD34+ve cells, Monocytes, lymphocytes and a variety of haemopoietic cell lines, indicating that the change to this critical residue in this gene may be functionally important. An analysis of a matched buccal sample showed that the HIST1H4C R3C variant in the PV patient was germline. Subsequent sequencing of the entire open reading frame of HIST1H4C in 232 normal individuals did not identify any other amino acid substitutions affecting this gene. Given the interaction of this residue with DNMT3A, we are currently investigating functional effects associated with this histone H4 variant. We have generated HEK293 cells with 4-Hydroxy tamoxifen (4-HT) inducible expression of the H4 R3C variant, and following the addition of 4-HT, we are initially assessing changes in histone H4 post-translational modifications, and markers of DNA damage such as gamma H2AX serine 139 phosphorylation. Disclosures: No relevant conflicts of interest to declare.

Biphenotypic Blast Phase (B-BP) of Chronic Myeloid Leukemia (CML): A Single Institution Experience

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1687-1687
Author(s):  
Hady Ghanem ◽  
Hagop M. Kantarjian ◽  
Elias Jabbour ◽  
Lakshmikanth Katragadda ◽  
Jorge E. Cortes ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Kinase Inhibitor ◽  
Conflicts Of Interest ◽  
Chronic Phase ◽  
Median Number ◽  
Cancer Center ◽  
Molecular Characteristics ◽  
Blast Phase ◽  
Extramedullary Disease

Abstract Abstract 1687 Approximately two thirds of patients with CML BP exhibit a myeloid phenotype, and one third a lymphoid phenotype. In rare occasions, patients exhibit a mixed phenotype. Biphenotypic blast phase (Bi-BP) are rare and generally portend a very unfavorable prognosis. To evaluate the incidence and outcome of Bi-BP, we reviewed 1143 patients with CML BP diagnosed and treated at M.D. Anderson Cancer Center between November 1973 and February 2012. Only Bi-BP with both myeloid and B-lymphoid differentiation was included in this analysis. Twelve (1%) patients had Bi-BP. At presentation, the median age was 62 years (range, 29–81), WBC count 12×109/L (range, 6–214), hemoglobin 10 g/dL (range, 7–14), platelet count 94×109/L (range, 41–531), peripheral blood blasts 30% (range, 0–83), and bone marrow blasts 66% (range, 0–91). Five (42%) patients had extramedullary disease involving the central nervous system (CNS; n=2), lymph nodes (n=2), and CNS, orbit and skin without bone marrow disease (n=1) (Table 1). The median time from diagnosis to transformation was 15 months (range, 0–58). Six patients expressed a b2a2 BCR-ABL1 transcript (p210), whereas 4 patients expressed b3a2 (p210) and in 2 patients such information was not available. Three patients presented initially with BP and 9 evolved to BP from chronic phase (CP). Out those 9, 6 had failed imatinib, 3 interferon, 1 dasatinib, 1 ara-C and 1 hydroxyurea prior to transformation. Median number of treatments prior to BP was 1 (range, 1 to 3). Initial therapy for Bi-BP was hyper-CVAD in 2 patients, one of them achieving complete cytogenetic remission (CCyR); hyper-CVAD and dasatinib in 1 patient, achieving a marrow CR; idarubicin, ara-C, and imatinib followed by allogeneic stem cell transplantation in 1 patient, with no response; idarubicin, ara-C, vincristine and dexamethasone in 1 patient, achieving CCyR; troxicitabine in 1 patient, achieving CCyR; combination of decitabine and imatinib in 1 patient, achieving CCyR; azacitidine and valproic acid in 1 patient with no response; and imatinib with homoharrangtonine in 1 patient with no response. Overall, 5 patients responded, to a variety of chemotherapy regimens that included a tyrosine kinase inhibitor in 2 of them. Median duration of response was 7 months (range, 1–55). One patient died during induction chemotherapy. A total of 5 patients received subsequent therapy: TKI in 3 patients and allogeneic SCT in 2 patients. Three patients developed BCR-ABL1 gene mutations: Y253H (n=1), T315I (n=1), and F317L & V299L (n=1). At last follow up, 10 patients were dead (5 due to progression) and 2 were lost to follow up. In conclusion, Bi-BP is a rare entity, which frequently exhibits an aggressive course, extramedullary disease, and high resistance to conventional chemotherapy. Therapy requires the use of chemotherapy in combination with a TKI. Nevertheless, responses are short-lived and patients should be offered allogeneic SCT or novel investigational approaches. Table 1. Summary of patients' clinical and molecular characteristics, response to treatments and outcomes Disclosures: No relevant conflicts of interest to declare.

Order Matters: Sequence Of Mutation Acquisition In Myeloproliferative Neoplasms Impacts Disease Pathogenesis and Stem Cell Potency

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2888-2888 ◽  
Author(s):  
David G. Kent ◽  
Christina Ortmann ◽  
Yvonne Silber ◽  
Joanna Baxter ◽  
Beatriz Bellosillo ◽  
...  
Keyword(s):  
Stem Cell ◽  
Double Mutant ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Clonal Evolution ◽  
Driver Mutations ◽  
Disease Evolution ◽  
Single Mutant ◽  
Tet2 Mutation ◽  
The Mean

Abstract Cancers evolve as a consequence of the stepwise accumulation of somatic lesions, with competition between subclones and sequential subclonal evolution. Some driver mutations arise either early or late in the evolution of different individual tumors, indicating that the final malignant properties of a subclone reflect the sum of mutations acquired rather than the order in which they arose. However virtually nothing is known about the cellular consequences of altering the order in which mutations are acquired. The myeloproliferative neoplasms (MPNs) readily permit clonal analysis and are chronic malignancies, thereby facilitating the dissection of disease evolution and intra-tumoral clonal architecture. In this study, we genotyped >7000 colonies from 24 MPN patients who harbored mutations in both JAK2 and TET2. We found that mutation of JAK2 and TET2 each occurred first in 12/24 patients, with TET2-first and JAK2-first patients observed in all 3 MPN subtypes. Patients who acquired a TET2 mutation first presented on average 12.3 years later than JAK2-first patients (p=0.0043) and had a lower proportion of JAK2V617F homozygous erythroid colonies (p=0.0001) suggesting that the order of acquisition affected both cellular composition and disease evolution. Moreover, compared to TET2-first patients, JAK2-first patients had an increased frequency of megakaryocyte/erythrocyte progenitors (p=0.0001) and decreased frequency of common myeloid progenitors (p=0.001). In order to determine whether disease evolution was also affected at the stem cell level, we isolated individual HSCs (lin-CD34+CD38+CD90-CD45RA+) and found that JAK2 single-mutant HSCs were significantly less prevalent than their JAK2/TET2 double-mutant counterparts. In marked contrast, TET2 single-mutant HSCs were significantly more prevalent than JAK2/TET2 double-mutant HSCs, suggesting that TET2 single-mutant HSCs exhibit a substantial self-renewal advantage and were not out-competed by their double-mutant progeny. Consistent with this interpretation, functional progenitor expansion from single cell cultures of individual HSCs (as assessed by secondary colony formation) was differentially altered by the second mutation acquired. Whereas the mean number of secondary colonies produced by double-mutant HSCs was increased when TET2 was the second mutation (p=0.012), the mean number of colonies was decreased when JAK2 was the second mutation (p=0.002) despite both HSCs bearing the same set of genetic lesions. Together our data indicate that acquisition of a JAK2 mutation reduces the competitiveness of TET2 single mutant HSCs, whereas acquisition of a TET2 mutation enhances that of JAK2 single mutant HSCs. These observations represent the first demonstration that the order of mutation acquisition influences stem and progenitor cell behaviour and clonal evolution in cancer. Disclosures: No relevant conflicts of interest to declare.

Tet2 Loss Accelerates The Myeloproliferative Neoplasm (MPN) Phenotype Of Jak2V617F Knockin Mice But Is Insufficient To Cause Leukemic Transformation

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4095-4095
Author(s):  
Edwin Chen ◽  
Lawrence J Breyfogle ◽  
Rebekka K. Schneider ◽  
Luke Poveromo ◽  
Ross L. Levine ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Myeloproliferative Neoplasm ◽  
Conditional Knockout ◽  
The Other ◽  
Myelogenous Leukemia ◽  
Leukemic Transformation ◽  
The Impact

Abstract TET2 mutations are early somatic events in the pathogenesis of acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPN) and are one of the most common genetic lesions found in these diseases. In MPN, TET2 mutations are enriched within more advanced disease phenotypes such as myelofibrosis and leukemic transformation and often co-occur with the JAK2V617F mutation, which is present in the majority of MPN patients. We have developed and characterized a Jak2V617F conditional knockin mouse (Jak2VF/+), the phenotype of which closely recapitulates the features of human MPN. To determine the impact of Tet2 loss on Jak2V617F-mediated MPN, we crossed Tet2 conditional knockout mice with Jak2VF/+ knockin and Vav-Cre transgenic mice and backcrossed the compound mutant animals. We then characterized the effects of heterozygous and homozygous loss of Tet2 on the phenotype of Jak2VF/+ mice. We assessed peripheral blood counts, histopathology, hematopoietic differentiation using flow cytometry, colony formation and re-plating capacity. We also evaluated the effects of Tet2 loss on the transcriptome of the HSC compartment using gene expression microarrays and on HSC function using competitive bone marrow transplantation assays. Similar to Jak2VF/+/VavCre+ mice, Tet2+/-/Jak2VF/+/VavCre+ and Tet2-/-/Jak2VF/+/VavCre+ mice develop leukocytosis, elevated hematocrits (HCT) and thrombocytosis. Tet2-/-/Jak2VF/+/VavCre+ mice demonstrate enhanced leukocytosis and splenomegaly compared to the other groups. All groups demonstrate myeloid expansion, erythroid hyperplasia and megakaryocytic abnormalities consistent with MPN in the bone marrow and spleen, while more prominent myeloid expansion and megakaryocytic morphological abnormalities are observed in Tet2-/-/Jak2VF/+/VavCre+ mice as compared to the other groups. Notably, we do not see the development of acute myelogenous leukemia (AML) in Tet2-/-/Jak2VF/+/VavCre+ mice at 6 months. We see enhanced expansion of lineagelowSca1+cKithigh (LSK) cells (enriched for HSC) most prominently in the spleens of Tet2+/-/Jak2VF/+/VavCre+ and Tet2-/-/Jak2VF/+/VavCre+ mice as compared to Jak2VF/+/VavCre+ mice. In colony forming assays, we find that Tet2-/-/Jak2VF/+/VavCre+ LSK cells have enhanced re-plating activity compared to Jak2VF/+/VavCre+ LSK cells and that Tet2-/-/Jak2VF/+/VavCre+ LSK cells form more colonies that Tet2-/-/Jak2+/+/VavCre+ cells. Gene expression analysis demonstrates enrichment of a HSC self-renewal signature inTet2-/-/Jak2VF/+/VavCre+ LSK cells. Concordant with this, we find that Tet2-/-/Jak2VF/+/VavCre+ LSK cells have enhanced competitive repopulation at 16 weeks as compared to Jak2VF/+/VavCre+ and Tet2+/-/Jak2VF/+/VavCre+ LSK cells. In aggregate these findings demonstrate that Tet2 loss promotes disease progression in MPN but is insufficient to drive full leukemic transformation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals LNK mutation studies in blast-phase myeloproliferative neoplasms, and in chronic-phase disease with TET2, IDH, JAK2 or MPL mutations

Leukemia ◽  
2010 ◽  
Vol 24 (10) ◽  
pp. 1713-1718 ◽  
Author(s):  
A Pardanani ◽  
T Lasho ◽  
C Finke ◽  
S T Oh ◽  
J Gotlib ◽  
...  
Keyword(s):  
Myeloproliferative Neoplasms ◽  
Chronic Phase ◽  
Blast Phase

scholarly journals Epidemiology of Patients with Classical Philadelphia-Chromosome Negative Myeloproliferative Neoplasms at a Single Academic Medical Center in Singapore

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5478-5478
Author(s):  
Priscella Shirley Chia ◽  
Vanessa CL Chong ◽  
Ting Yuan Tay ◽  
Eng Soo Yap ◽  
Wee Joo Chng ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Ethnic Groups ◽  
Research Funding ◽  
Myeloproliferative Neoplasms ◽  
Local Population ◽  
Philadelphia Chromosome ◽  
Leukemic Transformation ◽  
Female Ratio ◽  
Platelet Counts ◽  
The Mean

Abstract Introduction: Myeloproliferative Neoplasms (MPNs) represents a disorder that involves abnormal proliferation of cells originating from the myeloid line. The proliferation of these cells can lead to complications that are at times fatal. Despite its potential to cause life threatening complications, there is little data on this disease in Southeast Asia. As Singapore is a multiracial country in Southeast Asia, there may be some disease characteristics exclusive to patients here due to its unique population composition. The data from this Southeast Asian cohort would be useful to determine disease homogeneity in Asian countries. Methods: A retrospective review of the MPN database from National University Hospital, Singapore (NUHS) revealed 320 patients who were clinically diagnosed with MPN from 2008 to 2017. This data included patients with Essential Thrombocythemia (ET), Polycythemia Rubra Vera (PRV), Primary Myelofibrosis (PMF), Myeloproliferative Neoplasm, unclassifiable (MPN-U) and Chronic Eosinophilic Leukemia (CEL) (Figure 1A) as per the 2017 WHO classification. For this analysis, we included only the classical Philadelphia chromosome negative MPN and focused on the epidemiology, transformation and overall survival rate. Results: There was a slight male predominance with a male to female ratio of 1.3:1. The ethnic groups within this cohort consisted of 65.8% ethnic Chinese, 20.7% Malay, 5.5% Indian and the rest were made up of other ethnic groups within the region such as Eurasians, Thai, Filipinos, Burmese, Indonesians, Bangladeshi, Vietnamese and Arabian patients. The mean age at diagnosis for this group was 60.5. The mean age was 59.2 years for ET, 61.2 for PRV and the mean age of PMF was the oldest at 63.8. The mean age of diagnosis for ET and PMF patients in our cohort was slightly older compared to the Korean cohort (55.4 and 59.5 years) (Byun, et al., 2016). The majority of this cohort was made up of ET patients (53.1%) followed by PRV (35.3%) and PMF (11.6%). 77.5% of these patients were JAK2 V617F mutation (JAK2) positive. The percentage of patients who were JAK2 positive for ET, PRV and PMF were 69.2%, 96.9% and 56.3% respectively. The percentage of JAK2 positive patients for the three subtypes were higher in our local population compared to the Chinese and Japanese cohorts. Only 120 patients were tested for Calreticulin Exon 9 (CALR) mutations as this molecular test was only available in our institution from 2015 onwards. ET patients make up 68.4% of CALR positive patients. It was noted that CALR positive patients had comparatively higher mean platelet counts of 925.2 than CALR negative patients with mean platelet counts of 691.7. This phenomenon is seen in both CALR positive ET and CALR positive MF patients. In the 10-year period, 25 patients were lost to follow up and 8 patients transferred their care to another institution. Overall, 27 patients were deceased, with a mean survival of 3.5 years. The death-to-case ratio was 11.5 per 100 cases. The death-to-case ratio for ET, PRV and PMF is 6.1 per 100, 8.2 per 100 and 31.3 per 100 respectively. During this period, only 6 patients had transformation. Three patients progressed to post-ET myelofibrosis and 3 had leukemic transformation. Those who had leukemic transformation were initially diagnosed with PRV (1 patient) and PMF (2 patients). All patients who had leukemic transformation were deceased and had a mean survival of 1.4 years from the transformation event. Conclusion: Whilst there were some observable differences between our data and existing Asian data, there is still insufficient information to determine disease homogeneity. This is partly due to the rapid growth of molecular knowledge in this field and the regular revision of the WHO diagnostic criteria of MPNs over the last decade or so. There needs to be coordinated efforts within the region to ensure that our patients have equal access to these diagnostic platforms and that they receive an accurate diagnosis. Disclosures Chng: Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Aslan: Research Funding; Merck: Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, accommodation, expenses.

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