scholarly journals Molecular Cloning of Translocation t(1;14)(q21;q32) Defines a Novel Gene (BCL9) at Chromosome 1q21

Blood ◽  
1998 ◽  
Vol 91 (6) ◽  
pp. 1873-1881 ◽  
Author(s):  
T.G. Willis ◽  
I.R. Zalcberg ◽  
L.J.A. Coignet ◽  
I. Wlodarska ◽  
M. Stul ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Response To Therapy ◽  
Cdna Clones ◽  
Fish Analysis ◽  
Long Distance ◽  
B Cell Malignancies ◽  
Low Level ◽  
Chromosome 1Q21

Abstract Abnormalities of chromosome 1q21 are common in B-cell malignancies and have been associated with a poor response to therapy. The nature of the involved gene(s) on chromosome 1q21 remains unknown. A cell line (CEMO-1) has recently been established from a patient with precursor-B–cell acute lymphoblastic leukemia (ALL), which exhibited a t(1;14)(q21;q32). To identify the gene involved in this translocation, we have cloned both rearranged IGHJ alleles using long-distance inverse polymerase chain reaction (LDI-PCR). TwoIGHJ fragments were amplified from CEMO-1 DNA and sequenced. One allele showed novel sequences upstream of JH5 with no homology to either IGH or any other sequences on the databases. Using a single-copy Xho I fragment immediately 5′ ofJH5, PAC clones were isolated and mapped to chromosome 1q21 on normal metaphases by fluorescence in situ hybridization (FISH), confirming that this allele represented the t(1;14)(q21;q32) breakpoint. Sequence analysis of the 1q21 XhoI fragment showed identity with an expressed sequence tag (EST), and this probe was therefore used to probe Northern blots. Two transcripts of 6.3 kb and 4.2 kb expressed at low level in mRNA from all tissues were detected: a third transcript of 1.6 kb was expressed only in thymus, spleen, and small intestine. Full-lengthBCL9 cDNA clones were obtained from a normal human fetal brain cDNA library supplemented by 5′ and 3′ RACE. Sequence analysis predicted a protein of 1394 amino acids containing 18% proline, 11% glycine, 11% serine, and 6% methionine, but no recognizable protein motifs or significant homologies to any other known proteins. The CEMO-1 1q21 breakpoint fell within the 3′ UTR of the BCL9 gene. Low-level expression of BCL9 was detected in Epstein-Barr virus-transformed normal B cells by Northern blot; in contrast, abundant BCL9 expression was observed in CEMO-1, indicating that deregulated expression of this gene was one pathological consequence of the translocation. Screening of a panel of 39 B-cell malignancies with 1q abnormalities by Southern blot showed one additional case with a breakpoint in the 3′ UTR ofBCL9, indicating that this was a recurrent breakpoint. FISH analysis using an 850-kb YAC spanning BCL9 identified a further case with t(1;22)(q21;q11) causing juxtaposition of BCL9 to theIGλ locus. Other breakpoints were heterogeneous, falling both centromeric (10 cases) and telomeric (10 cases) of the BCL9gene. These data suggest that BCL9 may be the target of translocation in some B-cell malignancies with abnormalities of 1q21 and that deregulated BCL9 expression may be important in their pathogenesis.

scholarly journals Molecular Cloning of Translocation t(1;14)(q21;q32) Defines a Novel Gene (BCL9) at Chromosome 1q21

Blood ◽  
1998 ◽  
Vol 91 (6) ◽  
pp. 1873-1881 ◽  
Author(s):  
T.G. Willis ◽  
I.R. Zalcberg ◽  
L.J.A. Coignet ◽  
I. Wlodarska ◽  
M. Stul ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Response To Therapy ◽  
Cdna Clones ◽  
Fish Analysis ◽  
Long Distance ◽  
B Cell Malignancies ◽  
Low Level ◽  
Chromosome 1Q21

Abnormalities of chromosome 1q21 are common in B-cell malignancies and have been associated with a poor response to therapy. The nature of the involved gene(s) on chromosome 1q21 remains unknown. A cell line (CEMO-1) has recently been established from a patient with precursor-B–cell acute lymphoblastic leukemia (ALL), which exhibited a t(1;14)(q21;q32). To identify the gene involved in this translocation, we have cloned both rearranged IGHJ alleles using long-distance inverse polymerase chain reaction (LDI-PCR). TwoIGHJ fragments were amplified from CEMO-1 DNA and sequenced. One allele showed novel sequences upstream of JH5 with no homology to either IGH or any other sequences on the databases. Using a single-copy Xho I fragment immediately 5′ ofJH5, PAC clones were isolated and mapped to chromosome 1q21 on normal metaphases by fluorescence in situ hybridization (FISH), confirming that this allele represented the t(1;14)(q21;q32) breakpoint. Sequence analysis of the 1q21 XhoI fragment showed identity with an expressed sequence tag (EST), and this probe was therefore used to probe Northern blots. Two transcripts of 6.3 kb and 4.2 kb expressed at low level in mRNA from all tissues were detected: a third transcript of 1.6 kb was expressed only in thymus, spleen, and small intestine. Full-lengthBCL9 cDNA clones were obtained from a normal human fetal brain cDNA library supplemented by 5′ and 3′ RACE. Sequence analysis predicted a protein of 1394 amino acids containing 18% proline, 11% glycine, 11% serine, and 6% methionine, but no recognizable protein motifs or significant homologies to any other known proteins. The CEMO-1 1q21 breakpoint fell within the 3′ UTR of the BCL9 gene. Low-level expression of BCL9 was detected in Epstein-Barr virus-transformed normal B cells by Northern blot; in contrast, abundant BCL9 expression was observed in CEMO-1, indicating that deregulated expression of this gene was one pathological consequence of the translocation. Screening of a panel of 39 B-cell malignancies with 1q abnormalities by Southern blot showed one additional case with a breakpoint in the 3′ UTR ofBCL9, indicating that this was a recurrent breakpoint. FISH analysis using an 850-kb YAC spanning BCL9 identified a further case with t(1;22)(q21;q11) causing juxtaposition of BCL9 to theIGλ locus. Other breakpoints were heterogeneous, falling both centromeric (10 cases) and telomeric (10 cases) of the BCL9gene. These data suggest that BCL9 may be the target of translocation in some B-cell malignancies with abnormalities of 1q21 and that deregulated BCL9 expression may be important in their pathogenesis.

scholarly journals t(6;14)(p22;q32): a new recurrent IGH@ translocation involving ID4 in B-cell precursor acute lymphoblastic leukemia (BCP-ALL)

Blood ◽  
2008 ◽  
Vol 111 (1) ◽  
pp. 387-391 ◽  
Author(s):  
Lisa J. Russell ◽  
Takashi Akasaka ◽  
Aneela Majid ◽  
Kei-ji Sugimoto ◽  
E. Loraine Karran ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Survival Data ◽  
Lymphoblastic Leukemia ◽  
Response To Therapy ◽  
Chromosome 9 ◽  
Chromosome Band ◽  
Cell Precursor ◽  
Long Distance ◽  
Recurrent Translocation

Translocations involving the immunoglobulin heavy chain locus (IGH@) at chromosome band 14q32 are common in mature B-cell neoplasms, but are rare in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Here, we report the translocation, t(6;14)(p22;q32), involving IGH@ as a novel recurrent translocation in 13 BCP-ALL patients. Fluorescence in situ hybridization and long-distance inverse polymerase chain reaction (PCR) identified ID4 as the partner gene. Breakpoints were scattered over a 19kb region centromeric of ID4. Quantitative real-time PCR showed up-regulation of ID4 mRNA. All patients had deletions of CDKN2A and PAX5 located on the short arm of chromosome 9, frequently as a result of an isochromosome, i(9)(q10) (9/13, 69%). This study defines a new subgroup of BCP-ALL characterized by ID4 over-expression and CDKN2A and PAX5 deletions. Preliminary survival data suggest that this subgroup may be associated with a good response to therapy.

scholarly journals Lymphoblast purine pathway enzymes in B-cell acute lymphoblastic leukemia

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 330-332 ◽  
Author(s):  
GH Reaman ◽  
J Blatt ◽  
DG Poplack
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Metabolic Pathway ◽  
Purine Nucleoside Phosphorylase ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cells ◽  
Malignant Cells ◽  
B Cell Malignancies ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Purine Pathway

Abstract Activities of enzymes of the purine metabolic pathway, adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and 5′- nucleotidase (5′-N), were investigated in the lymphoblasts of a patient with B-cell acute lymphoblastic leukemia. These lymphoblasts exhibited increased ADA activity and diminished activities of both PNP and 5′N' as compared to normal lymphocytes as well as non-T, non-B leukemia cells. This enzymatic pattern is identical to that which has been described in T-cell leukemic lymphoblasts and differs from that which has been observed in the malignant cells of undifferentiated B-cell lymphomas. These data suggest that there is biochemical heterogeneity within the spectrum of B-cell malignancies. Furthermore, inhibitors of ADA may be of use in those B-cell lymphoid neoplasms that exhibit increased ADA activity.

Long Distance Trans DNA Hypomethylation in Cyclin D1 Deregulated B Cell Malignancies.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 390-390
Author(s):  
Hui Liu ◽  
Jin Wang ◽  
Jing Huang ◽  
Elliot M. Epner
Keyword(s):  
B Cell ◽  
Cyclin D1 ◽  
Normal Chromosome ◽  
Cyclin D3 ◽  
Chromosome 11 ◽  
Dna Hypomethylation ◽  
Long Distance ◽  
B Cell Malignancies ◽  
Mantle Cell ◽  
Methylation Patterns

Abstract Cyclin D1 is a common target gene in B cell malignancies. Cyclin D1 is deregulated by translocation in most patients with mantle cell lymphoma (MCL) and 15–20% of patients with multiple myeloma (MM). Cyclin D1 is not expressed in normal lymphocytes. Gene targeting experiments in cyclin D1 overexpressing MCL and MM were carried out and genetic variants isolated which had lost the translocated or inserted 11:14 chromosomes. These clones no longer expressed cyclin D1 but expressed high levels of cyclin D3. Analysis of DNA methylation patterns in these clones demonstrated that the translocated chromosome exerts a long distance trans DNA hypomethylating effect on the normal chromosome (transvection) at the cyclin D1 locus and at least 100 kilobases upstream. Thus, in the absence of the translocated chromosome, the normal chromosome is densely DNA methylated. This long distance trans hypomethylating effect was also demonstrated in a MM cell line (U266) which contains an insertion rather than a translocation of IgH sequences. Combined FISH/ immunofluorescent antibody labelling studies have shown the presence of both the normal and translocated chromosome 11’s at the outer nucleolar membrane, where they are tethered by the proteins CTCF and nucleophosmin, as demonstrated using chromatin immunoprecipitation assays. Tethering of the translocated and nontranslocated chromosomes by CTCF/nucleophosmin provides a mechanism for pairing and long distance DNA transhypomethylation.

Two Distinct Subsets of dic(9;12)(p12;p11.2) among Children with B-Cell Precursor Acute Lymphoblastic Leukemia (ALL): PAX5-ETV6 and ETV6-RUNX1 Rearrangements: A Report from the Children’s Oncology Group.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1439-1439 ◽  
Author(s):  
Julie M. Gastier-Foster ◽  
Andrew J. Carroll ◽  
Denise Ell ◽  
Richard Harvey ◽  
I-Ming Chen ◽  
...  
Keyword(s):  
B Cell ◽  
Gene Rearrangement ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Cytogenetic Abnormality ◽  
Fish Analysis ◽  
Oncology Group ◽  
Rt Pcr ◽  
Cell Precursor ◽  
Pediatric All

Abstract The dic(9;12)(p12;p11.2) has been described as a rare cytogenetic abnormality in pediatric precursor B-cell ALL. Initial studies suggested that the rearrangement is associated with a favorable outcome, and recent studies demonstrated the presence of a PAX5-ETV6 fusion gene was associated with this cytogenetic abnormality. Twenty cases with a cytogenetic dic(9;12) were identified in the Children’s Oncology Group (COG) cytogenetics databases. FISH analysis with the ETV6-RUNX1 (TEL-AML1) probes was done on 12 of these samples. Five cases were positive for fusion, indicating a cryptic t(12;21)(p13;q22), and also had loss of the ETV6 probe from the chromosome 12 not involved in the t(12;21). Seven cases were negative for fusion and had loss of an ETV6 signal, although one of the latter had a diminished ETV6 signal identified. To determine whether both PAX5-ETV6 and ETV6-RUNX1 rearrangements occurred in some patients, a diagnostic sample from each patient was analyzed by RT-PCR for the PAX5-ETV6 and ETV6-RUNX1 fusion genes. Primers from exon 3 of PAX5 and exon 3 of ETV6 were used for the PAX5-ETV6 analysis and from exon 5 of ETV6 and exon 4 of RUNX1 for the ETV6-RUNX1 analysis. Of the 20 cases, only 8 were RT-PCR positive for the PAX5-ETV6 fusion with the above primers; however, an additional 2 were RT-PCR positive with alternate primers, and all 10 of these were negative for the ETV6-RUNX1 fusion by RT-PCR. Of the remaining 10 patients, 9 were RT-PCR positive for the ETV6-RUNX1 fusion, including all of the ETV6-RUNX1 cases positive by FISH. The gene rearrangement associated with the dic(9;12) in these cases is not known. One patient was negative for both fusions by RT-PCR, negative by FISH for ETV6-RUNX1 rearrangement, yet had loss of an ETV6 signal. No cytogenetic differences could be seen between the 2 groups, either in the appearance of the dic(9;12) or in the other abnormalities identified. These results demonstrate the presence of two mutually exclusive dic(9;12) rearrangements in pediatric ALL; one associated with ETV6-RUNX1 rearrangement and one resulting in PAX5-ETV6 fusion. Both PAX5-ETV6 and ETV6-RUNX1 rearrangements are associated with a favorable prognosis. However, molecular analysis of the dic(9;12) patients must be performed to determine whether the dicentric chromosome results in PAX5-ETV6 fusion or whether the case has ETV6-RUNX1 fusion.

Karyotypic and Molecular Cytogenetic Findings in Childhood T-Cell Acute Lymphoblastic Leukemia (ALL): The Schneider Children’s Medical Center of Israel (SCMCI) Experience

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4861-4861
Author(s):  
Bati a Stark ◽  
Marta Jeison ◽  
Jaquelina Heker ◽  
Jacques Mardoukh ◽  
Gili Halevi-Berko ◽  
...  
Keyword(s):  
T Cell ◽  
Cytogenetic Analysis ◽  
Medical Center ◽  
Lymphoblastic Leukemia ◽  
Prognostic Significance ◽  
Response To Therapy ◽  
Mature Stage ◽  
Poor Responders ◽  
Fish Analysis ◽  
Prognostic Information

Abstract Introduction: Although outcome of Childhood T-ALL has improved significantly, it is still almost impossible to cure a relapsing patient. Currently, early response to therapy is considered the strongest predictor of outcome. Cytogenetics may contribute additional prognostic information in T-cell ALL. We used classical and molecular cytogenetics to screen the aberrations in T-ALL and study their correlation with immunophenotype and outcome. Methods: Cytogenetic analysis on cultured fresh BM specimens was performed as part of the routine diagnostic workup for every new ALL patient. Cytogenetic preparations were analyzed (part from archival material) by Fluorescence-In-Situ-Hybridization (FISH) on interphase nuclei, using commercially kits for: BCR/ABL1, MLL (Vysis), TLX1(HOX11), TLX3(HOX11L2), SIL-TAL1, TCRA/D on 14q11, TCRB on 7q34 (DakoCytomation) and P16 deletion on 9p21 (Cytocell). Results: Between Jan 1990 to April 2008, 79 newly diagnosed T-ALL patients, age 0.7–19 years, were treated at the SCMCI with 3 Israeli National Protocols based on the modified ALL-BFM 90/95 and IC-BFM 2002 studies. Five years EFS (median follow-up 8.5 yrs) is 71.9% (SE 5%), with 85.9% (SE 5.3%) for the MR group (prednisone-good-responders) (60% of patients), and 49.6% (SE 9.6%) for the HR group (prednisone-poor-responders) (40% of patients). Cytogenetic analysis was successful in 77 patients, and karyotype was abnormal in 59 (77%). In 19/59 pts (30%) 14q11 was involved: of them, four pts -t(11;14)(p13?15?;q11) (LMO1/2), three − t(10;14)(q24;q11)(TLX1), two − t(1;14)(p32;q11) (TAL1). Other non random translocations included: t(7;10)(q34;q24)-1pt and t(9;12)(q34;p13) with ABL1/ETV6 involvement – 1pt. By FISH analysis TLX1 split was detected in 2/33 samples, SIL-TAL1 fusion and TAL1 translocation in 5/55 samples, TLX3 split in 8/56 samples and MLL split in 6/61 samples. Additional secondary aberrations included 9p deletion in 16/55 samples, of them three pts had TLX3 split, three with SIL-TAL1 fusion/translocation, and one with t(9;12). del(9p) did not appear with the MLL split group. Episomal ABL1 amplification was detected in 2/63 samples, and in one of them it accompanied TLX3 split. Hyperdiploidy of <50 chromosomes and segmental numerical changes were frequent. By the European Group for the Immunological Characterization of Leukemias, the EGIL classification for T-ALL, 5% of patients had immature phenotype, 35% - Pre-T, 34% - cortical and 24% - mature stage. Of the 4pts with LMO1/2, three were Pre-T and one relapsed. All 4 pts with TLX1 involvement had cortical immunophenotype and none have relapsed. The 5 pts with TAL1 and 6 pts with MLL split exhibited various phenotypic stages and no relapse occurred among them. In contrast, of the 8 pts with TLX3 split, 4 (50%) relapsed within 2 years. In conclusion: The findings of non random primary translocations and the combinations with recurrent secondary genetic aberrations, suggest specific multistep pathways in leukomogenesis of T-Cell leukemia. In the context of the present intensive treatment based on the BFM protocols, only the TLX3 split group fared worse, but a larger study is needed to evaluate the prognostic significance of the various cytogenetic subgroups in T-ALL.

Prevalence and Clinical Characterization of CD20 and CD22 Expression in Pediatric Precursor B-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4872-4872
Author(s):  
Melissa S Rayburg ◽  
Daniel Marmer ◽  
Jun Mo ◽  
Richard McMasters ◽  
Teresa Smolarek ◽  
...  
Keyword(s):  
B Cell ◽  
Pediatric Population ◽  
Lymphoblastic Leukemia ◽  
Strong Association ◽  
Prognostic Significance ◽  
Response To Therapy ◽  
White Blood Count ◽  
Published Data ◽  
Prognostic Features ◽  
Cd20 Expression

Abstract Immunophenotypic classification of leukemia has important therapeutic and prognostic implications. In B-cell malignancies, CD20 and CD22 also represent therapeutic targets. CD20 expression in adult patients with B lineage ALL has been associated with a poor prognosis. The data are conflicting in the pediatric population and may be impacted by the type of therapy employed. A recent study of pediatric patients treated in consecutive St Jude Children’s Research Hospital Total Therapy ALL regimens observed excellent outcomes and no prognostic significance for CD20 expression (Jeha et al. Blood2006, 108:3302–3304). We retrospectively analyzed 50 consecutive patients aged 4 months to 28 years with precursor-B ALL treated with contemporary risk-adapted BFM-based ALL regimens for whom flow cytometric, genetic, and early response data were available. Cases were defined as positive for CD20 and/or CD22 expression if surface expression was identified in more than 20% of leukemic blasts. We found that CD22 was expressed at high levels (68–99%) in all patients evaluated. CD20 expression was positive in 27 (54%) of patients. CD20 expression did not correlate with known NCI prognostic features, including presenting white blood count or age. All 3 patients with BCR-ABL translocation ALL were CD20 positive. Consistent with previously published data, neither of the 2 patients with MLL-AF4 translocation were CD20 positive. There was no association of CD20 expression with trisomy 4/10/17 or TEL-AML1 status. We did not observe an association between CD20 expression and rapid early bone marrow response to therapy at day 8 or 15; 47/50 patients were in remission at day 29. At a median follow-up time of 48 months 46/50 patients were alive without relapse. These limited data do not suggest a strong association between CD20 expression and known prognostic features or early treatment response in pediatric precursor-B ALL treated with contemporary BFM therapy platforms. However, our findings of frequent expression of CD22 on precursor-B ALL blasts from children supports its consideration as a target for immunotherapy approaches in high risk or relapsed disease.

Outcome of Adults with Acute Lymphoblastic Leukemia Treated with a Pediatric-Inspired Therapy: A Single Institution Experience

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4337-4337
Author(s):  
Guillermo J. Ruiz-Delgado ◽  
Julio Macias-Gallardo ◽  
Julia Lutz-Presno ◽  
Maryel Montes-Montiel ◽  
Guillermo J. Ruiz-Arg\)elles
Keyword(s):  
Overall Survival ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Single Institution ◽  
B Cell Malignancies ◽  
Secondary Diabetes ◽  
Free Survival ◽  
Results Of Treatment ◽  
Better Than

Abstract Abstract 4337 The results of treatment of adults with ALL remain unsatisfactory. Pediatric-inspired treatments seem to be related with better outcomes. Eighty adult ALL patients were prospectively treated in a single institution in a 16-year period with a schedule based on the St. Jude's TOTAL XI pediatric protocol employing vincristine, prednisone, asparaginase, daunorubicin, etoposide, cytarabine, methotrexate, mercaptopurine and triple intratecal therapy. Median age was 31 years (range 18 – 86); 92% were B-cell malignancies and 14% were Ph1 (+). Ten patients did not complete the first course of chemotherapy and 4 exited early. 44 of 66 patents (67%) achieved a complete remission; relapses presented in 57%. The median probability of overall survival (OS) was 28 months, whereas the 144-month OS was 27%. The median probability of leukemia-free survival (LFS) was 28 months, and the 144-month LFS 35%. Ph1 (+) patients did worse than Ph1-negative and T-cell leukemias did better than B-cell ones. Concerning toxicity, eight patients had toxic deaths (12%), two developed acute pancreatitis and one secondary diabetes. This pediatric-inspired therapy rendered better results than those obtained in similar socioeconomic circumstances using adult-oriented treatments; tolerance was acceptable and costs were low since it employs affordable drugs and can be delivered as outpatients. Disclosures: No relevant conflicts of interest to declare.

ERG Intragenic Deletion Characterizes a Distinct Oncogenic Subtype of B-Cell Precursor Acute Lymphoblastic Leukemia with a Favourable Outcome Despite Frequent IKZF1 Deletions

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 121-121
Author(s):  
Emmanuelle Clappier ◽  
André Baruchel ◽  
Jérôme Rapion ◽  
Aurélie Caye ◽  
Ahlème Khemiri ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Favourable Outcome ◽  
Fish Analysis ◽  
Cell Precursor ◽  
Pcr Assay ◽  
Genetic Lesion ◽  
Intragenic Deletion

Abstract Abstract 121 The genetic landscape of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in children above 10 years and adolescents remains poorly defined. Specifically, more than half of these patients have none of the cytogenetic abnormalities that define oncogenic subtypes and underlie risk stratification. To uncover new genetic abnormalities in these unassigned cases, we studied 85 BCP-ALL from patients aged 10 to 17 diagnosed at St-Louis hospital (Paris, France), for which the main classifying genetic lesions were assessed (i.e. high hyperdiploidy, t(12;21)/ETV6-RUNX1, t(1;19)/TCF3-PBX1, t(9;22)/BCR-ABL1, iAMP21, MLL translocations, low hypodiploidy, and near haploidy). Fifty of these BCP-ALL presented no classifying genetic lesions. Paired leukemic and remission samples could be analysed by high density array-CGH (Agilent 1M arrays) in 17 of these unassigned cases. We focused on acquired, focal, and recurrent copy-number abnormalities. A mono-allelic intragenic deletion of the ETS-related Gene (ERG) was found in 3 cases. ERG belongs to the ETS family of transcription factors and is implicated in chromosomal translocations associated with several cancer types including acute myeloid leukemia. The possibility of a cryptic unbalanced translocation was ruled out in the 3 cases by FISH analysis. The deletions encompassed exons 3 to 7, or 3 to 9, and the breakpoints were tightly clustered. Based on the breakpoint sequences we designed a PCR assay that allowed us to screen ERG intragenic deletions in the whole cohort. ERG deletion was identified in 9 additional cases, none of them having any of the known classifying genetic lesions, bringing up to 25% (12 out of 50) the frequency of ERG deletion in unassigned BCP-ALL of children older than 10. These results suggested that ERG deletion characterized a novel oncogenic subtype of BCP-ALL. Of note, these results were consistent with independent data of Harvey et al. (2010) that reported ERG deletions in a distinct gene-expression cluster. To confirm and extend these findings in the whole population of paediatric BCP-ALL, we used our breakpoint-specific PCR assay to screen ERG deletions in an independent cohort of 822 unselected patients aged 1 to 17, enrolled in the EORTC 58951 trial. ERG deletion was identified in 31/822 (3.7%) patients. Again, none of them had another known classifying genetic lesion, confirming that ERG deletion characterizes a distinct oncogenic subtype. Patients with ERG deletion were significantly older compared to other patients (median 7.0 vs 4.0, p=0.002), but they had similar white blood counts at diagnosis. They had a favourable outcome, with a 8-year event free survival (EFS) of 82.4% and overall survival (OS) of 96.0%, which is similar to EFS of 83.4% and OS of 91.6% obtained for patients having no very high risk initial features (i.e. no t(9;22)/BCR-ABL1, MLL rearrangement or haploidy/low hypodiploidy). IKZF1 deletion is a cooperative genetic lesion that has been recently shown to be associated with a poor outcome in BCP-ALL. Remarkably, the incidence of IKZF1 deletions in patients with ERG deletion was significantly higher than in other BCR-ABL1-negative patients, especially when considering the IKZF1 intragenic deletion Δ4-7 (10/31, 32.3% vs 34/744, 4.6%, P<0.001), and this regardless of age. Surprisingly, IKZF1 deletion had no impact on the prognosis of ERG deleted patients. Indeed, patients combining ERG and IKZF1 Δ4-7 deletions had a better outcome than other BCR-ABL1-negative patients with IKZF1 deletions (8-year EFS 83.3% vs 53.0%, hazard ratio (HR) 0.19, 95% CI 0.02–1.41; p=0.069). Altogether, we have identified a novel oncogenic subtype of BCP-ALL characterized by ERG deletion. This subtype is frequently associated with IKZF1 deletions, suggesting a preferred oncogenic cooperation. Importantly, despite having older age and frequent IKZF1 deletions, which are factors usually predictive of a poor prognosis, patients with ERG deletion have a favourable outcome. Therefore, this genetic abnormality may be systematically assessed as part of the diagnostic work-up of BCP-ALL and taken into account when considering treatment stratification. Disclosures: No relevant conflicts of interest to declare.

Molecular Genetic Characterization of 3'-Deletion of MLL Gene in Infant Acute Leukemia.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2498-2498
Author(s):  
Grigory Tsaur ◽  
Olga Plekhanova ◽  
Alexander Popov ◽  
Tatyana Gindina ◽  
Yulia Olshanskaya ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Leukemia ◽  
Lymphoblastic Leukemia ◽  
Molecular Genetic ◽  
Fish Analysis ◽  
Long Distance ◽  
Mll Gene ◽  
Partner Gene ◽  
Genetic Features ◽  
Blast Cells

Abstract Abstract 2498 Background. MLL gene rearrangements are associated with unfavorable outcome in infant acute lymphoblastic leukemia (ALL) and have intermediate prognosis in infant acute myeloid leukemia (AML). Application of fluorescence in-situ hybridization (FISH) allows detecting not only conventional MLL rearrangements, but also concurrent 3'-deletion of MLL gene. However, detailed characteristics of infant leukemia carrying 3' MLL deletion remain unclear. Aim. To investigate molecular genetic features of MLL-rearranged infant acute leukemia with concurrent 3' MLL deletion. Methods. 64 patients (27 boys and 37 girls) aged from 1 day to 11 months (median 6.6 months) including 44 ALL patients, 18 AML patients, 1 patient with acute bilineage leukemia and 1 patient with acute undifferentiated leukemia were enrolled in the current study. Chromosome banding analysis was done according to standard procedure. FISH analysis using LSI MLL Dual Color, Break Apart Rearrangement Probe (Abbott Molecular, USA) was performed on at least 200 interphase nuclei and on all available metaphases. Presence of MLL rearrangements was detected by FISH, reverse-transcriptase PCR. In 29 cases long-distance inverse PCR was additionally performed. In case of MLL rearrangement presence standard FISH pattern was defined as simultaneous detection of 3 different fluorescent signals: 1 fused (orange) signal, 1 green signal derived from 3' part of MLL gene, 1 red signal from 5' end of MLL (1F1G1R). MLL rearrangements with concurrent 3' MLL deletion led to 1F1R FISH pattern formation due to lack of green signal. Results. FISH revealed MLL rearrangements in 73% of ALL cases that was higher than frequency of 11q23 translocations detected by conventional cytogenetics — 55%. In MLL-positive cases we found 38 patients (81%) with standard FISH pattern, 7 ones (15%) with concurrent 3'-deletion of MLL gene and 2 (4%) with complex MLL rearrangements. Among patients with 3' MLL deletions there were 1 case with 5' MLL duplication (1F2R) and 1 case with 5' MLL triplication (1F3R). Frequency of 3'-deletions were similar in ALL and AML patients (13% and 15%, respectively). We did not find more than one FISH pattern in bone marrow blast cells of each patient with 3' MLL deletion. In this cohort of patients all blast cells carried concurrent 3'-deletion of MLL gene. Moreover, percentage of blast cells carrying MLL rearrangements did not differ significantly between patients with standard FISH pattern (median 97%, range 22–100%) and 3'-deletion (median 83%, range 13–99%) (p=0.206). 3'-deletion of MLL was not associated with breakpoint position in MLL gene and type of translocation partner gene. MLL translocation partner genes detected in patients with 3' deletions were as follows AF4(n=2), MLLT3(n= 3), MLLT10(n=2). None of the patients with 3'-deletions had reciprocal fusion gene. Initial patients' characteristics (age, sex, WBC count, immunophenotype, CNS-status, type of MLL partner gene) and treatment response parameters (day 8 peripheral blood blast cell count, day 15 bone marrow status, day 36 remission achievement, minimal residual disease status at time point 4) did not differ significantly between 2 groups. Although cumulative incidence of relapse was lower in patients with 3'-deletion as compared to patients with standard FISH pattern (0.31±0.04 and 0.55±0.01, respectively), difference between these two groups was not statistically significant (p=0.359). Conclusion. In our work we characterized rare subgroup of infant MLL-rearranged acute leukemia carrying concurrent 3' MLL deletion. Our data provide additional information of molecular genetic features of acute leukemia in children younger than one year. Disclosures: No relevant conflicts of interest to declare.

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