Faculty Opinions recommendation of Acute myeloid leukemia with biallelic CEBPA gene mutations and normal karyotype represents a distinct genetic entity associated with a favorable clinical outcome.

Purpose CEBPA mutations are found as either biallelic (biCEBPA) or monoallelic (moCEBPA). We set out to explore whether the kind of CEBPA mutation is of prognostic relevance in cytogenetically normal (CN) acute myeloid leukemia (AML). Patients and Methods Four hundred sixty-seven homogeneously treated patients with CN-AML were subdivided into moCEBPA, biCEBPA, and wild-type (wt) CEBPA patients. The subgroups were analyzed for clinical parameters and for additional mutations in the NPM1, FLT3, and MLL genes. Furthermore, we obtained gene expression profiles using oligonucleotide microarrays. Results Only patients with biCEBPA had an improved median overall survival when compared with patients with wtCEBPA (not reached v 20.4 months, respectively; P = .018), whereas patients with moCEBPA (20.9 months) and wtCEBPA had a similar outcome (P = .506). Multivariable analysis confirmed biCEBPA, but not moCEBPA, mutations as an independent favorable prognostic factor. Interestingly, biCEBPA mutations, compared with wtCEBPA, were never associated with mutated NPM1 (0% v 43%, respectively; P < .001) and rarely associated with FLT3 internal tandem duplication (ITD; 5% v 23%, respectively; P = .059), whereas patients with moCEBPA had a similar frequency of mutated NPM1 and a significantly higher association with FLT3-ITD compared with patients with wtCEBPA (44% v 23%, respectively; P = .037). Furthermore, patients with biCEBPA showed a homogeneous gene expression profile that was characterized by downregulation of HOX genes, whereas patients with moCEBPA showed greater heterogeneity in their gene expression profiles. Conclusion Biallelic disruption of the N and C terminus of CEBPA is required for the favorable clinical outcome of CEBPA-mutated patients and represents a distinct molecular subtype of CN-AML with a different frequency of associated gene mutations. These findings are of great significance for risk-adapted therapeutic strategies in AML.

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Clinical usefulness of plasma specimens for detection of nucleophosmin 1 gene mutations in patients with normal karyotype acute myeloid leukemia

Leukemia Research ◽

10.1016/j.leukres.2011.04.023 ◽

2011 ◽

Vol 35 (9) ◽

pp. e159-e160 ◽

Cited By ~ 1

Author(s):

Sang Hyuk Park ◽

Sook-Kyung Min ◽

Borae G Park ◽

Seongsoo Jang ◽

Chan-Jeoung Park ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Gene Mutations ◽

Normal Karyotype ◽

Clinical Usefulness ◽

Acute Myeloid

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RAS, KIT and FLT3 Gene Mutations in inv(16)/t(16;16)-Positive Acute Myeloid Leukemia (AML): Incidence and Relevance on Clinical Outcome.

Blood ◽

10.1182/blood.v108.11.2303.2303 ◽

2006 ◽

Vol 108 (11) ◽

pp. 2303-2303

Author(s):

Juan Du ◽

Richard F. Schlenk ◽

Andrea Corbacioglu ◽

Marianne Habdank ◽

Claudia Scholl ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Clinical Outcome ◽

Myeloid Leukemia ◽

Mutation Screening ◽

Significant Proportion ◽

Gene Mutations ◽

Prognostic Impact ◽

Significant Difference ◽

Postremission Therapy ◽

Acute Myeloid

Abstract Inversion or translocation of chromosome 16 inv(16)/t(16;16) [hereafter abbreviated inv(16)] represent common cytogenetic abnormalities in adult acute myeloid leukemia (AML). At the molecular level inv(16) result in the generation of the CBFb-MYH11 fusion protein that is known to interfere with the heterodimeric transcription factor RUNX1/CBFb and thereby contributes to impaired differentiation of hematopoietic cells. Patients (pts.) with inv(16) are considered to have a favorable outcome, in particular when treated with cytarabine-based consolidation regimens. However, a significant proportion of these pts. relapse and survival after 5 years is about 60%. These findings together with studies from murine models suggest that additional genetic lesions are underlying the clinical heterogeneity of inv(16)-positive AML. The recently described mutations in the signaling molecules FLT3, KIT and RAS represent potential secondary genetic lesions that might contribute to leukemic transformation through constitutive activation. In this study we determined the incidence of KIT (exons 8, 10, 11, and 17), FLT3 (ITD; TKD at D835/I836,) and RAS (NRAS/KRAS exon1, exon2) mutations in 94 adult AML pts. (16 to 60 years; median age 41 years) with inv(16) and evaluated their prognostic impact on clinical outcome. KIT and RAS mutation screening was performed using a sensitive DHPLC-based assay; samples with abnormal profile were confirmed by direct sequencing. FLT3 mutations were identified as previously described. Pts. were entered on 3 AMLSG treatment trials [AML HD93, AML HD98A, AMLSG 07–04]. Postremission therapy implied cytarabine-based (HiDAC n=57) regimens as well as autologous (n=23) or allogeneic (n=13) stem cell transplantation (SCT) in first CR. Mutations were identified in 84% of inv(16) AML with highest frequencies in NRAS (47%) followed by KIT (26%) and FLT3-TKD (15%); 10/24 KIT mutations affected exon17. KRAS and FLT3-ITD mutations were detected in 10% and 3%, respectively. Complete remission (CR) rate was 90% for the whole group. In univariable analyses, FLT3-TKD mutations were associated with a significant inferior relapse-free survival (RFS) (p=0.01). For the other mutations there was no significant difference in RFS when comparing mutated and unmutated pts. Multivariable analysis adjusted for postremission therapy revealed FLT3-TKD (HR 2.39, p=0.04) and in trend KIT exon17 mutations (HR 2.8, p=0.06) as adverse prognostic factors. Therefore, an explorative subgroup analysis was performed for KIT exon17 mutations for the different postremission strategies. In pts. treated with HiDAC, KIT exon17 mutations were associated with a significant inferior RFS (p<0.0001), in contrast to pts. receiving SCT (p=0.70). For overall survival (OS) none of the tested variables were significantly associated with prognosis. KIT, FLT3, or RAS gene mutations can be detected in 84% of inv(16)-positive AML further sustaining the model of cooperating gene mutations. Although the numbers are still quite small, FLT3-TKD and KIT exon17 mutations are of prognostic relevance; the prognostic impact of KIT exon17 mutations seems to be abrogated by SCT strategies. Thus, KIT and FLT3 mutation status might reach clinical importance with regard to the availability of specific inhibitors and the type of postremission therapy.

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TET2, ANPM1 and FLT3-ITD Gene Mutations in Normal Karyotype Acute Myeloid Leukemia

Blood ◽

10.1182/blood.v120.21.1413.1413 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1413-1413

Author(s):

Aining Sun ◽

Xiaopeng Tian ◽

Jia Yin ◽

Weiyang Li ◽

Suning Chen ◽

...

Keyword(s):

Bone Marrow ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Gene Mutations ◽

Normal Karyotype ◽

Genetic Mutation ◽

Wild Type ◽

Cell Percentage ◽

High Bone ◽

Acute Myeloid

Abstract Abstract 1413 Objective: Analyze the molecular genetics characteristics of acute myeloid leukemia with normal karyotype and explore the relationship between different genetic mutation patterns and prognosis. Methods: A total of 373 acute myeloid leukemia (AML) with normal karyotype diagnosed and treated in the First Affiliated Hospital of Soochow University from 2005 to 2010 were recruited in this research to assess the genetic mutation patterns. The target genes which was extracted from bone marrow cell were amplified by PCR and analyzed by massively DNA sequencing. All of the TET2, DNMT3A, IDH1, IDH2, EZH2, CBL, ASXL1, MLL-PTD, NPM1, WT1, RUNX1, c-KIT, FLT3-ITD, FLT3-TKD, N-RAS and JAK2V617F gene mutations were detected in our study. Results: (1). A total of 16.1% of patients had TET2 mutations, 31.6% had FLT3 internal tandem duplications (ITDs), 6.2% had FLT3 tyrosine kinase domain mutations, 2.4% had c-KIT mutations, 37.8% had NPM1 mutations, 11.3% had WT1 mutations, 5.9% had RUNX1 mutations, 11.5% had ASXL1 mutations, 3.8% had MLL partial tandem duplications (PTDs), 7.8% had IDH1 mutations, 7.8% had NRAS mutations, 12.3% had IDH2 mutations, 1.6% had EZH2 mutations, 14.7% had DNMT3A mutations and no mutations were found of CBL and JAK2V617F. In conclusion, there are 77% (287/373) gene mutations hide in normal karyotype AML patients.(2). We found that the TET2 gene mutations were associated with DNMT3A (P = 0.041) and RUNX1 (P <0.001) mutations, but mutually exclusive with IDH2 (P = 0.021), or IDH1/2 (P = 0.006) gene mutations. NPM1 gene mutations were highly correlated with DNMT3A mutations (P <0.0001), IDH1 mutations (P <0.0001) and IDH2 mutations (P = 0.001), but mutually exclusive with RUNX1 mutations (P=0.003). IDH2 mutations and WT1 mutations were mutually exclusive (P = 0.01); DNMT3A mutations were associated with NRAS mutations (P = 0.01). In addition, study have shown that the number of gene mutations was closely associated with older age, high white blood cell and high bone marrow blast cell percentage, but wasn't correlated with gender, hemoglobin and platelet levels.(3). In the NPM1m+ patients, TET2 mutations were associated with shorter median OS in contrast to TET2 wild type (9.9 vs. 27.0 months, P= 0.023). Surprisingly, in NPM1m+/FLT3-ITDm- group, TET2 mutations was also an unfavorable prognostic factor, which was closely associated with shorter median OS compared to TET2 wild type (9.5 vs. 32.2 months, P=0.013). Conclusion: Gene mutations incidence was high in normal karyotype AML patients. TET2 mutations was an unfavorable prognostic factor which was closely associated with shorter median OS in contrast to TET2 wild type in NPM1m+/FLT3-ITDm-group. In addition, The number of gene mutation was closely associated with older age, high white blood cell levels and high bone marrow blast cell percentage. Disclosures: No relevant conflicts of interest to declare.

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Clinical Relevance of Concomitant Gene Mutations in CEBPA Double-Mutated Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v120.21.2400.2400 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2400-2400

Author(s):

Vera Grossmann ◽

Susanne Schnittger ◽

Niroshan Nadarajah ◽

Sandra Weissmann ◽

Annette Fasan ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Clinical Outcome ◽

Survival Data ◽

Myeloid Leukemia ◽

Melting Curve ◽

454 Sequencing ◽

Normal Karyotype ◽

Equity Ownership ◽

Cebpa Mutations ◽

Acute Myeloid

Abstract Abstract 2400 Background: CEBPA mutations occur in 5–14% of patients with acute myeloid leukemia (AML). A difference in clinical outcome between single- (sm) and double-mutated (dm) cases has been reported, whereupon dm cases were shown to be associated with longer overall (OS) and event-free survival (EFS). Aims: 1. Determine the frequency and clinical impact of CEBPA sm and dm in a large AML cohort. 2. Evaluate the spectrum of additional molecular mutations in CEBPA dm AML and their prognostic influence. Patients and Methods: First, we investigated CEBPA mutations in a cohort of 997 AML cases (462 female, 535 male; median age: 66.8 years) by 454 deep-sequencing (454 Life Sciences, Branford, CT). The cohort included: t(15;17)(q22;q12) n=33; t(8;21)(q22;q22) n=39; inv(16)(p13q22) n=31; normal karyotype (NK) n=447; complex karyotype (CK) (≥4 abnormalities) n=116; other abnormalities n=331. Second, we investigated an additional cohort of 111 AML dm CEBPA cases for mutations in ASXL1, DNMT3A, FLT3-ITD, FLT3-TKD, GATA2, IDH1/2, KRAS, MLL-PTD, NPM1, NRAS, RUNX1, TET2, TP53, and WT1 using 454 sequencing, Sanger sequencing, conventional PCR and melting curve analyses. This cohort was composed of 60 female and 51 male cases; median age: 62.3 years; 76 cases showed NK, 19 aberrant karyotype (n=4 n.a.). Survival data was available in 90/111 (81.1%) cases. Results: 1. In total, CEBPA mutations were detected in 75/997 (7.5%) of cases (t(15;17)(q22;q12) n=2/33; NK n=52/447; CK n=1/116; other abnormalities n=20/331). Of the 75 patients with CEPBA mutations 31 (41.3%) were sm, while 44 (58.7%) were dm. Patients with dm CEPBA showed better outcome compared to sm cases (OS at 3 yrs: 78.9% vs 38.5%, P=0.014; EFS after 3 yrs: 53.9% vs 36.6%, P=0.108). OS and EFS of CEBPA sm cases were comparable to CEPBA wt cases (OS at 3 yrs: 38.5% and 43.6%, P=0.689, EFS at 3 yrs: 36.6% and 29.4%, P=0.678). OS of CEBPA dm cases was comparable to patients with t(15;17)(q22;q12) (OS after 3 yrs: 78.9% vs 86.1%, P=0.597). 2. In the cohort of 111 patients we detected 227 CEBPA mutations. In 106 (95.5%) cases two mutations, and in 5 (4.5%) cases three mutations were detected. The median mutation load was 42% (range: 2–98%). The majority of mutations were frame-shift (n=135) and in-frame (n=66). Further, missense (n=19) and nonsense (n=7) mutations were observed. Most cases showed one N- and one C-terminal mutation (92/111, 82.8%), 10 (9.0%) cases harbored two N-terminal mutations, and 4 (3.6%) cases showed two C-terminal mutations. In addition, two cases showed one N- and two C-terminal mutations, two cases two N- and one C-terminal mutations, and one case harbored three N-terminal mutations. In 92/111 (82.9%) cases we observed at least one additional mutation (mean: 1.6 mutations; range: 1–4): TET2 39/109 (35.8%), ASXL1 20/111 (18.0%), GATA2 20/111 (18.0%), WT1 14/111 (12.6%), DNMT3A 11/109 (10.1%), IDH1/2 9/111 (8.1%) (IDH1 n=2, IDH2 n=7), NRAS 9/111 (8.1%), RUNX1 7/111 (6.3%), FLT3-ITD 7/111 (6.3%), KRAS 4/109 (3.7%), NPM1 3/111 (2.7%), FLT3-TKD 2/110 (1.8%), MLL-PTD 1/111 (1.0%), and TP53 1/110 (1.0%). With respect to clinical outcome we observed no differences in OS for concomitant mutations in DNMT3A, FLT3-ITD, IDH1/2, NRAS, TET2 and WT1. Cases with additional GATA2 mutations showed longer survival than wt cases (OS at 3 yrs: 100% versus 73.4%, P=0.026, EFS at 3 yrs: 67.5% versus 48.5%, P=0.137). In contrast, cases harboring additional ASXL1 or RUNX1 mutations were associated with worse outcome (ASXL1: OS at 3 yrs: 32.8% versus 85.7%, P<0.001, EFS at 3 yrs: 0% versus 57.9%, P=0.002; RUNX1: OS at 3 yrs: 0% versus 81.8%, P=0.001, EFS at 3 yeaers: 0% versus 53.8%, P=0.003). Since mutations in ASXL1 and RUNX1 frequently occurred concomitantly, they were grouped together (n=21). When then separating cases into (1) GATA2 mut, (2) GATA2 wt, ASXL1wt, RUNX1wt and (3) ASXL1mut and/or RUNX1mut we observed 3 distinct survival curves (OS at 3 yrs: 100% vs 81.2% vs 32.8, P<0.001, EFS at 3 yrs: 67.5% and 55.3% and 0%, P=0.005). No statistical analysis was performed for FLT3-TKD, KRAS, MLL-PTD, NPM1, TP53 due to the low number of mutations. Conclusions: 1. In CEBPA dm cases a high frequency of concomitant mutations (82.9%) was observed. 2. Most common mutated genes were TET2 (35.8%), ASXL1 (18.0%), GATA2 (18.0%), WT1 (12.6%), DNMT3A (10.1%), and RUNX1 (6.3%). 3. In CEBPA dm cases GATA2 mutations were associated with longer OS, whereas OS was poor in ASXL1 and/or RUNX1 mutated cases. Disclosures: Grossmann: MLL Munich Leukemia Laboratory: Employment. Schnittger:MLL Munich Leukemia Laboratory: Equity Ownership. Nadarajah:MLL Munich Leukemia Laboratory: Employment. Weissmann:MLL Munich Leukemia Laboratory: Employment. Fasan:MLL Munich Leukemia Laboratory: Employment. Eder:MLL Munich Leukemia Laboratory: Employment. Stopp:MLL Munich Leukemia Laboratory: Employment. Kern:MLL Munich Leukemia Laboratory: Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership. Kohlmann:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership.

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Prognostic Impact and Concurrent Genetic Alterations of CEBPA Double Mutations in Adults with Cytogenetically Intermediate-Risk Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v120.21.2538.2538 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2538-2538

Author(s):

Shunichiro Yamaguchi ◽

Kenji Tokunaga ◽

Eisaku Iwanaga ◽

Tomoko Nanri ◽

Taizo Shimomura ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Transcription Factor ◽

Clinical Outcome ◽

Myeloid Leukemia ◽

Gene Mutations ◽

Prognostic Impact ◽

Intermediate Risk ◽

Disease Entity ◽

Cebpa Mutations ◽

Acute Myeloid

Abstract Abstract 2538 Aims: Among acute myeloid leukemia (AML) patients with intermediate-risk cytogenetics, C/EBPa mutations represent a distinct disease entity with a favorable clinical outcome and is adopted in the current WHO classification of AML as a provisional disease entity in the category AML with recurrent genetic abnormalities. CEBPA encodes a transcription factor that is essential for neutrophil development. AML patients with CEBPA mutations can be separated into two subgroups with a single mutation in the CEBPA (CEBPA sm) and double mutations (CEBPA dm). Biallelic mutations consisted of an N-terminal frameshift mutation and a C-terminal inframe bZIP mutation were detected in the majority of CEBPA dm, whereas CEBPA sm occurs in either N-terminal or C-terminal regions. More recent data indicate that favorable outcome is mainly observed in AML patients with CEBPA dm but not with CEBPA sm. In addition, concurrent gene mutations may occur more frequently in AML with CEBPA sm than in CEBPA dm. In contrast, transcription factor GATA2 mutations are frequently identified in AML with CEBPA dm. In this study, we examined incidence, concurrent gene mutations and clinical significance of CEBPA dm and CEBPA sm in Japanese adults with cytogenetically intermediate-risk AML. Methods: To identify the prevalence and prognostic impact of CEBPA dm and CEBPA sm, we examined 111 patients with intermediate-risk AML who were mainly treated with the JALSG protocols. Age ranged from 16 to 86 years, with a median of 58.5 years. DNA was extracted from bone marrow or peripheral blood mononuclear cells at diagnosis and subjected to PCR amplification and direct sequencing of the CEBPA, FLT3, NPM1, IDH1, IDH2, DNMT3A and GATA2 genes. This study was approved by the Institutional Review Boards and informed consent was obtained from each patient according to guidelines based on the revised Declaration of Helsinki. Results: Of 111 cytogenetically intermediate-risk AML, we found 12 (10.8%) CEBPA dm and 7 (6.3%) CEBPA sm. In 7 CEBPA sm, one NPM1 mutation and one FLT3-ITD were detected. Two FLT 3-ITD and no concurrent mutation of NPM1 were found in CEBPA dm. No mutation in the IDH1, IDH2, DNMT3A exon 23 was identified in both patients with CEBPA sm and CEBPA dm. On the other hand, mutations in the GATA2 zinc finger domains were detected in 3 of 12 (25%) patients with CEBPA dm. No GATA2 mutations were found in 7 CEBPA sm. One of 21 patients with wild-type CEBPA (CEBPA wt) had a GATA2 mutation. Patients with CEBPA double or single mutations showed a better 5-year overall survival (OS) compared to CEBPA wt (51.3% vs 16.0%, P=0.0048). CEBPA dm AML was associated with a significant superior clinical outcome compared with CEBPA wt (5-year OS, 55.6% vs 16.0%, P=0.0025). However, no significant difference was identified between CEBPA dm and CEBPA sm AML (5-years OS, 55.6% vs 42.9%, P=0.1375) or between CEBPA sm and CEBPA wt AML (5-year OS, 42.9% vs 16.0%, P=0.4827). In addition, the presence of additional GATA2 mutations did not significantly influence the clinical outcome of AML patients with CEBPA dm. Conclusions: A total of 19 (17.1%) patients with cytogenetically intermediate-risk AML harbored CEBPA mutations. Our study indicates that the presence of the CEBPA dm but not CEBPA sm is associated with favorable outcome in Japanese patients with cytogenetically intermediate-risk AML. Disclosures: No relevant conflicts of interest to declare.

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Chromosome Aberrations, Gene Mutations and Expression Changes, and Prognosis in Adult Acute Myeloid Leukemia

Hematology ◽

10.1182/asheducation-2006.1.169 ◽

2006 ◽

Vol 2006 (1) ◽

pp. 169-177 ◽

Cited By ~ 75

Author(s):

Krzysztof Mrózek ◽

Clara D. Bloomfield

Keyword(s):

Gene Expression ◽

Acute Myeloid Leukemia ◽

Chromosome Aberrations ◽

Myeloid Leukemia ◽

Molecular Genetic ◽

Prognostic Significance ◽

Gene Mutations ◽

Normal Karyotype ◽

Genetic Alterations ◽

Acute Myeloid

Abstract Pretreatment clinical features and prognosis of patients with acute myeloid leukemia (AML) are strongly influenced by acquired genetic alterations in leukemic cells, which include microscopically detectable chromosome aberrations and, increasingly, submicroscopic gene mutations and changes in gene expression. Cytogenetic findings separate AML patients into three broad prognostic categories: favorable, intermediate and adverse. The cytogenetic-risk classifications differ somewhat for younger adult patients and those aged 60 years or older. In many instances, patients with specific cytogenetic findings, e.g., those with a normal karyotype or those with either t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22) [collectively referred to as core-binding factor (CBF) AML] can be further subdivided into prognostic categories based on the presence or absence of particular gene mutations or changes in gene expression. Importantly, many of these molecular genetic alterations constitute potential targets for risk-adapted therapies. In this article, we briefly review major cytogenetic prognostic categories and discuss molecular genetic findings of prognostic significance in two of the largest cytogenetic groups of patients with AML, namely AML with a normal karyotype and CBF AML.

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Analysis of NPM1 Gene Mutations in Chinese Adults with Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v108.11.4503.4503 ◽

2006 ◽

Vol 108 (11) ◽

pp. 4503-4503

Author(s):

De Pei Wu ◽

Lingzhi Yan ◽

Suning Chen ◽

Jianying Liang ◽

Yufeng Feng

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Residual Disease ◽

Direct Sequencing ◽

Gene Mutations ◽

Normal Karyotype ◽

Chinese Patients ◽

Chinese Adults ◽

Cytoplasmic Transport ◽

Acute Myeloid

Abstract Many European groups have described that mutations at exon-12 of the nucleophosmin (NPM1) gene are the most frequent genetic lesion in acute myeloid leukemia (AML) (45.7%~61.7% of all adult AMLs with normal karyotype). This outstanding discovery provides a promising minimal residual disease (MRD) marker for AMLs with normal karyotype. To clarify the prevalence and the clinical profile of NPM1 mutations in Chinese patients with AML, we analyzed a cohort of 156 newly diagnosed adult AMLs for this mutation. Genomic DNAs were prepared from bone marrow samples of these patients. NPM1 exon 12 mutations were detected using direct sequencing or fragment analysis of DNA-PCR products. NPM1 mutations were present in 28.2% of the overall population, including 1/1(100%) of M0, 11/27(40.7%) of M1, 11/46(23.9%) of M2, 0/29(0%) of M3, 2/9(22.2%) of M4, 18/39(46.2%) of M5 and 1/5(20.0%) of M6. NPM1 gene mutations were more prevalent in patients with a normal karyotype (37 of 90; 41.1%), when compared with patients with karyotypic abnormalities (7 of 66; 10.6%; P<0.001). Sequence analysis of 25 NPM1 mutated cases revealed known mutations (type A, B, NM, and PM) as well as 1 novel sequence variation (here named as type S). All mutational types were heterozygous and showed a 4 bp insertion between position nucleotide 960 and 961 (Genebank accession number: NM-002500). NPM1 mutations were significantly associated with old age (P<0.05), high peripheral white cell count (P<0.05) and FAB-M1/M5, but negatively associated with expression of CD34 (P<0.05) and CD117 (P<0.05). In conclusion, NPM1 mutations also represent a common genetic abnormality in Chinese adults with AML, especially in the presence of a normal karyotype. The occurrence of NPM1 mutations indicates an age-dependent characteristic. NPM1 mutated cases show a special clinical subtype of AML. Further studies are urgently needed to confirm the role of NPM1 mutations in leukemogenesis. The altered nucleo-cytoplasmic transport of NPM1 mutated protein is probably a potential therapic target for AML with NPM1 mutations.

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Nucleophosmin Gene Mutations Exhibit High Spontaneous Apoptosis and Favorable Prognosis in Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v110.11.3480.3480 ◽

2007 ◽

Vol 110 (11) ◽

pp. 3480-3480

Author(s):

Giovanni Del Poeta ◽

Emanuele Ammatuna ◽

Serena Zaza ◽

Francesco Buccisano ◽

Tiziana Ottone ◽

...

Keyword(s):

Cell Proliferation ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Prognostic Significance ◽

Gene Mutations ◽

Normal Karyotype ◽

Proliferative Potential ◽

Spontaneous Apoptosis ◽

Favorable Prognosis ◽

Acute Myeloid

Abstract Nucleophosmin gene mutations (NPM1-Mt) are the hallmark of a large adult acute myeloid leukemia (AML) subgroup with normal karyotype and interact with p53 and its regulatory molecules (Arf, Hdm2/Mdm2), thus lowering cell proliferation and increasing apoptosis (Falini, 2007). Moreover, AML pts show co-existing NPM1-Mt and internal tandem duplications of FLT3 (FLT3-ITD) which increase potential for cell proliferation. Furthermore, genes and proteins involved in apoptosis, such as bcl-2 and bax, have been demonstrated to be relevant in response to treatment and outcome (Del Poeta, 2003). Therefore, we analysed NPM1-Mt, FLT3-ITD and apoptosis proteins (bcl-2 and bax) in 222 pts, affected by de novo non-M3 AML, median age 60 years, treated with intensive chemotherapy regimens according to GIMEMA-EORTC protocols. The aims of our study were: to correlate NPM1-Mt or FLT3-ITD with bax/bcl-2 ratio levels, as a measure of spontaneous apoptosis; to assess the independent prognostic significance of NPM1-Mt and FLT3-ITD. Bcl-2 and bax proteins were determined by multicolor flow cytometry and bax/bcl-2 ratio was obtained by dividing mean fluorescence intensity (MFI) of bax/MFI bcl-2. The threshold of positivity was set at the median value >0.35 (range 0.01–9.1). NPM1 mutations and FLT3-ITD were detected by multiplex PCR and capillary gel electrophoresis. One hundred-twenty-one/222 (54.5%) pts were bax/bcl-2 ratio positive, 54/222 (24.3%) were NPM1-Mt and 52/222 (23.4%) presented FLT3-ITD; 17/222 (7.6%) pts carried both FLT3-ITD and NPM1-Mt. There was a strong correlation between higher WBC counts (>100x109/L) and FLT3-ITD (P<0.00001), confirming their high proliferative potential. On the contrary, a higher apoptosis (bax/bcl-2 ratio>0.35) and NPM1-Mt without FLT3-ITD were significantly associated (30/37; P=0.0001), demonstrating that NPM1-Mt alone express high amount of spontaneous apoptosis. Moreover, NPM1-Mt cases were significantly related to FAB M4 or M5 AML (P=0.03). A normal karyotype was found in 37/45 (82%) NPM1-Mt pts (P=0.00001) and almost all NPM1-Mt cases were CD34 negative (47/54; P<0.00001). With regard to clinical outcome, a significant higher complete remission (CR) rate was found in NPM1-Mt/FLT3-ITD negative pts (90%) vs NPM1-Mt/FLT3-ITD+ (35%) or only FLT3-ITD+ cases (47%) [P=0.0002]. Equally, overall survival (OS) was significantly longer in NPM1-Mt/FLT3-ITD negative pts in comparison with NPM1-Mt/FLT3-ITD+ or only FLT3-ITD+ cases (35% vs 0% vs 6% at 2 years; P=0.00007). Furthermore, NPM1-Mt/FLT3-ITD negative subset showed a disease free survival longer than only FLT3-ITD+ cases (44% vs 0% at 1.2 years; P=0.008). Finally, NPM1-Mt/FLT3-ITD negative pts showed a better outcome than the large subgroup negative both for NPM1-Mt and FLT3-ITD, with regard to CR (90% vs 66%) and OS (35% vs 15% at 2 years). In multivariate analysis, bax/bcl-2 ratio (P<0.00001), age (P=0.0003) and FLT3-ITD (P=0.01) were significant for CR, while bax/bcl-2 ratio (P<0.00001), WBC count (P=0.01) and FLT3-ITD (P=0.01) resulted to be independent prognostic factors for OS. In conclusion, we demonstrated that NPM1 mutations exhibit high levels of spontaneous apoptosis, which strenghten, in the absence of FLT3-ITD, their favorable prognosis. On the contrary, FLT3-ITD dominate the myeloid leukemic phenotype conferring a poor outcome to pts with NPM1 mutations.

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