Estradiol Induces Gene Proximity and MLL-MLLT3 Fusion In An AICDA-Mediated Pathway

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 806-806
Author(s):  
Andrew T Vaughan ◽  
Rebecca Wright ◽  
Katrina Slemmons
Keyword(s):  
Acute Leukemia ◽  
Dna Cleavage ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Hot Spot ◽  
Clinical Samples ◽  
Common Mechanism ◽  
Mll Gene ◽  
Increased Risk ◽  
Translocation Breakpoints

Abstract Translocation breakpoints involving the MLL gene linked to Infant Acute Leukemia (IAL) and therapy related acute leukemia (tAL) are tightly clustered between MLL exons 8 and 12. Exon 12 also marks the location of a well-described cleavage hotspot that is synchronous with a sharp decline in total MLL fusions observed in clinical samples. Though multiple MLL fusion partners have been identified, fusions to MLLT3 (AF9) and AFF1 (AF4) comprise 56% of all clinical rearrangements so far assayed. Epidemiological data has linked maternal exposure to birth control formulations with an increased risk of IAL involving MLL gene rearrangements. Subsequent in-vitro studies suggested a role of estradiol (E2) in the generation of such rearrangements. In order to probe the action of E2 in generating these lesions, the ability of E2 to impact MLL rearrangement formation was studied, focusing on the exon 12 hotspot and using immortalized but not transformed TK6 lymphoblastoid cells. Real-time PCR studies showed that in this cell line, transient exposure to 10 nM E2 enhanced transcription of MLL eight fold over controls. E2 treatment also increased transcription of MLL partner genes, MLLT3 and AFF1, through to a lesser degree. To determine if the process of transcription led to gene co-localization, chromatin conformation capture (3C) experiments were performed. Here, brief exposure to 10 nM E2 led to the co-localization of MLL with MLLT3, using primer sets targeting both MLL introns 9 and 13 and MLLT3 introns 4 and 8. These data indicated contact between these two genes, over a substantial region, consistent with their occupation of an operationally defined “transcription factory”. Surprisingly, low levels of E2 also stimulated the generation of de-novo MLL- MLLT3 fusion transcripts, without the application of any genotoxic stressors. To identify the process whereby each gene is fragmented, an essential precursor to any rearrangement, RNAi knockdown of activation induced cytidine deaminase (AICDA) was studied. AICDA activity is normally associated with class switch recombination and somatic hypermutation, but has recently been identified as the fragmenting agent associated with c-myc/IgH fusions in Burkitts lymphoma. RNAi knockdown of AICDA suppressed the induction of MLL-MLLT3 fusion transcript formation observed with E2 treatment, suggesting AICDA involvement in MLL and partner gene fragmentation. To probe this association in more detail, a ChIP analysis was performed targeting AICDA recruitment to MLL intron 11 (hot spot for rearrangements) or intron 12 (few MLL rearrangements). Here, E2 dependent localization of AICDA was noted upstream of the DNA cleavage hotspot and within the region of elevated MLL fusions in intron 11, but not in a region showing few rearrangements. Combined, these studies show that concentrations of E2 that occur during pregnancy, or during use of oral contraceptives, have the potential to initiate MLL fusions through an endogenous AICDA-mediated mechanism, that is enhanced by gene proximity associated with synchronous transcription of both MLL and partner genes. Further, the link between transcription-induced co-localization and MLL rearrangements may identify a common mechanism of MLL fusion gene formation relevant to a wider range of clinical diagnoses. If correct, then this mechanism may be a target for manipulation, particularly in controlled settings such as the delivery of potentially leukemogenic therapeutics. Disclosures: No relevant conflicts of interest to declare.

Association of A313g Glutathione S-Transferase P1 (GSTP1) Inborn Polymorphism with Susceptibility to De Novo MDS

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1445-1445
Author(s):  
Sophia Zachaki ◽  
Chryssa Stavropoulou ◽  
Aggeliki Daraki ◽  
Marina Kalomoiraki ◽  
Panagoula Kollia ◽  
...  
Keyword(s):  
De Novo ◽  
Conflicts Of Interest ◽  
Type A ◽  
Common Mechanism ◽  
Genotype Distribution ◽  
Distribution Analysis ◽  
Wild Type ◽  
Increased Risk ◽  
Variant Genotype

Abstract Abstract 1445 Models for the pathogenesis of myelodysplastic syndromes (MDS) imply the role of individual genetic variations in genes involved in detoxification mechanisms. GSTP1 enzyme plays a key role in detoxification of a variety of electrophilic compounds, such as benzo [a]-pyrene and other polycyclic aromatic hydrocarbons (PAHs), chemotherapy drugs and products of oxidative stress. GSTP1 acts through a common mechanism of conjugating reactive oxygen species (ROS) with glutathione, enabling their detoxification and elimination and thus defending tissues against DNA damage. The corresponding gene is subject to a single-nucleotide polymorphism (A313G) leading to abolished enzyme activity. Thus, individuals homozygous for the variant G allele (G/G) have a lower conjugating activity than individuals homozygous for the wild type A allele (A/A), while heterozygotes (A/G) display intermediate activity. The aim of the present study was to evaluate whether the GSTP1 polymorphism influences susceptibility to MDS and/or promote specific chromosomal aberrations. We conducted a case-control study in 310 de novo MDS patients and 370 unrelated healthy controls using both a conventional PCR-RFLP assay and a novel Real-Time PCR genotyping method using hybridization probe technology. The GSTP1 gene status was also evaluated in relation to patients' characteristics and chromosomal abnormalities. Comparison of the genotype distribution between controls and MDS cases revealed a significantly higher frequency of the variant genotypes (heterozygotes A/A and homozygotes G/G) among MDS patients, as compared to controls (p<0.0001, χ2=31.167, df=2). The most marked statistical difference between MDS patients and controls was observed between the wild-type (A/A) and the homozygous variant genotype (G/G), since subjects carrying the G/G variant genotype showed a 4.1-fold increased risk of MDS prevalence than subjects carrying the wild-type A/A genotype (p=0.000, χ2=30.5, d.f.=1, OR=4.098, 95%CI=[2.433–6.897]). Allele frequencies distribution analysis between patients and controls, showed that MDS patients exhibited a 1.9-fold increased risk of carrying at least one variant G allele, as compared to the controls (p<0.0001, d.f.=1, OR =1.9, 95%CI=[1.48–2.34]). There was no association between the GSTP1 polymorphism and gender or any specific cytogenetic subgroup, while stratification of patients according to age showed a differential GSTP1 genotype distribution (p=0.007). Our results, derived from the larger series of primary MDS cases tested for the GSTP1 genetic background, reveal an increased incidence of the GSTP1 variant genotypes among MDS patients, providing evidence for a potential pathogenetic role of the GSTP1 polymorphism on de novo MDS risk. Disclosures: No relevant conflicts of interest to declare.

Evaluation of Patients with Myelodysplastic Syndromes (MDS) Obtaining Stable Disease with the Use of Decitabine.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2790-2790
Author(s):  
Henry G. Kaplan ◽  
Michael Milder
Keyword(s):  
Stable Disease ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Clinical Importance ◽  
Hematologic Malignancies ◽  
Median Number ◽  
Outpatient Setting ◽  
Entire Cohort ◽  
Increased Risk

Abstract Abstract 2790 Poster Board II-766 BACKGROUND: MDS is a group of hematologic malignancies associated with reduced quality of life related to progressive cytopenias and increased risk of infections and bleeding. Successful treatment in MDS is typically defined in terms of complete remission (CR). Treatment with decitabine, a DNA methyltransferase inhibitor, has led to CR in 9 to 39% of MDS patients. Many patients have responses that do not meet criteria for CR or partial remission, but may be of clinical importance, especially for older MDS patients. Since patients who achieve stable disease may receive benefits from treatment, it was of interest to evaluate patient characteristics and treatment response results of those who achieved stable disease with decitabine. METHODS: 99 patients with de novo (n=88) or secondary (n=11) MDS were treated with decitabine, 20 mg/m2 daily for 5 days every 4 weeks in an outpatient setting (Steensma et al. J Clin Oncol 2009). No dose reductions were allowed but dose delays were permissible. Any FAB, including CMML, were eligible if ECOG 0-2 and normal hepatic and renal function. Supportive care, including blood products, were permitted. G-CSF was permitted for serious infection or sepsis. Twenty-three patients (18 de novo and 5 secondary MDS) achieved stable disease as the best response by IWG 2006 criteria. RESULTS: At baseline, stable disease patients had a median age of 75 years (70% >70 years) and were mainly men (70%). Ten patients had RA, 7 had RAEB, 4 had RAEB-t, and one each had RARS or CMML. The IPSS scores for these patients were Low (n = 1; 4%), INT-1 (n = 8; 35%), INT-2 (n = 5; 22%), and High (n = 9; 39%). Cytogenetics were good 10 (43%), 1 (4%) intermediate, 10 (43%) poor, or unknown 2 (9%). At baseline 19 (83%) were RBC transfusion dependent, 3 (13%) platelet transfusion dependent. 22 patients were ECOG 0-1. Five patients had received prior cytotoxic chemotherapy, none with azacitidine or decitabine. The median number of cycles initiated was 5.0 (range 2 – 19). At the time of the analysis, 12 of the 23 patients had died with a median survival of 19.2 months (95% CI: 9.4, not estimable). This is consistent with the survival response (19.4 months (95% CI: 15, not estimable) for the entire cohort, which included the stable disease patients, 50% who achieved a hematologic improvement or better, and 10% with progressive disease with decitabine (15% not assessable). Median time to AML or death was 16.1 months (95% CI: 7.2, not estimable). Three of 19 RBC-dependent patients at baseline became transfusion independent for at least 8 weeks with treatment. Conversely, 3 of 4 baseline RBC-independent patients became transfusion dependent. One of 3 platelet-dependent patients became transfusion independent. Three of 20 platelet-independent patients at baseline became transfusion dependent. Of ten patients evaluable for cytogenetic responses, 2 patients had partial cytogenetic responses. Eleven out of 23 patients had at least one related SAE. Myelosuppression-related adverse events were common (≥10%) in these 23 patients with grade 3 or higher adverse experiences of anemia (26%), febrile neutropenia (17%), neutropenia (39%), and thrombocytopenia (30%). CONCLUSIONS: In an outpatient setting, approximately one-quarter of MDS patients maintained stable disease with decitabine treatment, with acceptable and manageable toxicity. Overall survival in this subset of patients appeared to be similar to that observed with the entire cohort, which included 50% of patients with an objective clinical benefit. Larger analyses are needed to fully understand the characteristics of and treatment-related benefits for patients who achieve stable disease with decitabine treatment. Disclosures: No relevant conflicts of interest to declare.

Are CML Lymphoid Blast Crisis and Ph Positive ALL Genomically Indistinguishable?

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4464-4464
Author(s):  
Colin Grace ◽  
Elisabeth P Nacheva
Keyword(s):  
Tyrosine Kinase ◽  
Dna Sequences ◽  
Acute Leukaemia ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Hot Spot ◽  
Blast Crisis ◽  
Disease Stage ◽  
Blast Transformation ◽  
Significance Analysis

Abstract Abstract 4464 Philadelphia positive malignant disorders are a clinically divergent group of hemoblastoses with a unique identifying feature, the BCR/ABL1 fusion gene, usually resulting from the chromosome rearrangement t(9;22)(q34;q11) or its variants, that leads to constitutive expression of an aberrant tyrosine kinase. These include chronic myeloid leukaemia (CML) and de novo acute leukaemia of both myeloid Ph(+)AML and lymphoid origin Ph(+)ALL. The latter two disorders are clinically aggressive and therapy challenging even in the era of the powerful tyrosine kinase inhibitors. CML is a multistage progressive disease, which if untreated, inevitably ends as fatal acute leukaemia, either myeloid or lymphoid. The latter is often thought to be indistinguishable from Ph(+)ALL, the most common type of ALL in adults. We have identified DNA sequences the imbalances of which appear to be significantly associated with the disease stage and lineage origin in CML and Ph(+)ALL samples. We used array CGH at a resolution of ~2kb to explore hot spot regions obtained from 102 patient samples comprising 92 CML and controls together with 10 Ph(+)ALL and show how Significance Analysis of Microarrays (1) can be used to identify differences in the genome profile of de novo Ph(+)ALL and lymphoid blast transformation of CML. We show that lymphoid blast crisis CML differs significantly from Ph(+)ALL not only due to the presence of 9p deletions but also due to genomic gains in other chromosomes. Furthermore we identify a sub group of Ph(+)ALL with a distinctive genomic profile. Having identified genome regions of potential interest, ranked in order of significance, out of the 100's of thousands of array results, it is then a challenge to design further experiments to evaluate their contribution to the biology of the BCR/ABL positive disease. 1 Tusher V, Tibshirani R, Chu G: Significance analysis of microarrays applied to the ionizing radiation response. Proc Natl Acad Sci U S A 98:5116-5121 (2001). Disclosures: No relevant conflicts of interest to declare.

A Meta-Analysis of CAG (cytarabine, aclarubicin, G-CSF) Regimen for the Treatment of 1045 Patients with Leukemia in China and Japan,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3638-3638
Author(s):  
Guoqing Wei ◽  
Wanmao Ni ◽  
Dicky Chiao ◽  
He Huang ◽  
Zhen Cai ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Fixed Effects ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Meta Analysis ◽  
Early Death ◽  
Newly Diagnosed ◽  
Significant Difference ◽  
China And Japan ◽  
Better Than

Abstract Abstract 3638 Background: CAG regimen (cytarabine, aclarubicin, G-CSF) has been commonly used in China and Japan for the treatment of AML and MDS. This study is to summarize the data and to analyze the efficacy as well as the toxic effects of CAG regimen in acute leukemia (AL) and MDS pts. Methods: The databases of PubMed, Wanfang Data, as well as American Society of Hematology (ASH) annual meeting abstracts were searched for articles published in English, Chinese and Japanese languages between January 1995 and December 2010. Eligible studies were relevant clinical trials on AL and MDS pts treated with CAG regimen. Complete remission (CR) rates and odds ratio (OR) were compared through a meta-analysis using a random-effects or fixed-effects model. Results: 37 trials with a total of 1045 AL and MDS pts were included for analysis. Among the 1045 pts treated with CAG, 819 pts were AML, 215 pts were de novo MDS or transformed AML (MDS/tAML), 6 pts were ALL, and 5 pts were biphenotypic acute leukemia (BAL). The AML CR rate of CAG from 29 studies was 58.0% (95% CI, 53.1%-62.7%). The MDS/t-AML CR rate from 12 studies was 45.7% (95% CI, 39.0%-52.4%). The AML CR rate was significantly better than that of MDS /tAML (Q=8.072, p<0.01). Among 819 AML pts, 327 pts were newly diagnosed, 370 pts were relapsed/refractory (R/R) AML. The AML status was not specified in the rest 122 pts. Interestingly, no significant difference in CR rates was noted between the newly diagnosed (57.0%, 95% CI 51.5%-62.3%) and R/R AML pts (60.1%, 95% CI 50.5%-68.9%) (Q=0.312, p>0.05). The CR rate for the 367 elderly AML pts was 52% (95% CI 51.5%-62.3%). The CR rate was also significantly higher in pts with favorable (64.5%, 95% CI 38.8%-83.9%) and intermediate (69.6%, 95% CI 60.4%-77.5%) cytogenetics than those with unfavorable one (29.5%, 95% CI 19.7%-41.8%) (p<0.05). There were 7 trials that compared the CR rates of CAG regimen with those of other induction regimens in AML pts. Surprisingly, the CR rate of CAG was significantly higher than those of other induction regimens (OR 2.425, 95% CI, 1.515–3.880). CAG regimens were well tolerated with cardiotoxicity in 0.42% cases (4/954) and early death occurred in 4.40% cases (44/1000). Conclusions: CAG regimen induced significantly higher CR rates in AML than in MDS pts. The CR rates of CAG regimen was significantly better than those of other induction regimens in AML pts. This regimen was well tolerated with low cardiotoxicity and early death rate. Disclosures: No relevant conflicts of interest to declare.

DNMT3A Mutation Leads to Hematopoietic Dysregulation.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2382-2382
Author(s):  
Jie Xu ◽  
Wei-na Zhang ◽  
Tao Zhen ◽  
Yang Li ◽  
Jing-yi Shi ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Epigenetic Modification ◽  
Hematopoietic Cells ◽  
In Vitro Assays ◽  
Clinical Samples ◽  
Hematopoietic Stem

Abstract Abstract 2382 Epigenetic modification process is required for the development of hematopoietic cells. DNA methyltransferase DNMT3A, responsible for de novo DNA methylation, was newly reported to have a high frequency of mutations in hematopoietic malignancies. Conditional knock-out of DNMT3A promoted self-renewal activity of murine hematopoietic stem cells (HSCs). However, the role of mutated DNMT3A in hematopoiesis and its regulative mechanism of epigenetic network mostly remain unknown. Here we showed that the Arg882His (R882H) hotspot locus on DNMT3A impaired the normal function of this enzyme and resulted in an abnormal increase of primitive hematopoietic cells. In both controlled in vivo and in vitro assays, we found that the cells transfected by R882H mutant promoted cell proliferation, while decreased the differentiation of myeloid lineage compared to those with wild type. Analysis of bone marrow (BM) cells from mice transduced by R882H reveals an expansion of Lin−Sca-1+C-kit+ populations and a reduction of mature myeloid cells. Meanwhile, a cluster of upregulated genes and downregulated lineage-specific differentiation genes associated with hematopoiesis were discovered in mice BM cells with R882H mutation. We further evaluated the association of mutated DNMT3A and HOXB4 which was previously detected to be highly expressed in clinical samples carrying R882 mutation. Compared with wildtype DNMT3A, R882H mutation disrupted the repression of HOXB4 by largely recruiting tri-methylated histone 3 lysine 4 (H3K4). Taken together, our results showed that R882H mutation disturbed HSC activity through H3K4 tri-methylation, and transcriptional activation of HSC-related genes. Disclosures: No relevant conflicts of interest to declare.

Genetic and Clinical Characterization of 45 Acute Leukemia Patients with MLL Gene Rearrangements From a Single Institution.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2477-2477
Author(s):  
Nuno Cerveira ◽  
Susana Lisboa ◽  
Cecília Correia ◽  
Susana Bizarro ◽  
Joana Santos ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Acute Leukemia ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Consecutive Series ◽  
Gene Rearrangements ◽  
Fusion Partner ◽  
Older Children ◽  
Single Institution ◽  
Mll Gene

Abstract Abstract 2477 Background: MLL gene rearrangements are found in more than 70% of the cases of infant leukemia, both acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML), but are less frequent in leukemia from older children. MLL translocations are also found in approximately 10% of adult AML and in a small proportion of patients with therapy-related leukemia. Independently of their association with other high-risk features at presentation, MLL rearrangements are in most cases predictive of poor clinical outcome. In this study, we report the clinical characterization and frequency and type of MLL rearrangements present in a consecutive series of 45 patients that were diagnosed with acute leukemia in the Portuguese Oncology Institute, Porto, Portugal, over the last 13 years (1998–2011). Patients and Methods: Conventional cytogenetic, fluorescence in situ hybridization (FISH), and molecular genetic studies (RT-PCR and LDI-PCR) were used to characterize the type and frequency of MLL rearrangements in a consecutive series of 45 Portuguese patients with MLL-related leukemia treated in a single institution between 1998 and 2011. Additionally, a detailed patient clinical characterization was also performed and statistical analysis using the Kaplan-Meier method as used to evaluate patient survival. Results: In 43 patients (96% of the cases) we could identify the fusion partner, the most common being the MLLT3, AFF1, MLLT1, MLLT10, ELL, and MLLT4 genes, accounting for 88% of all cases. In the group of patients with acute lymphoblastic leukemia and an identified MLL fusion partner, 47% showed the presence of an MLL-AFF1 fusion, as a result of a t(4;11). In the remaining cases, a MLL-MLLT3 (27%), a MLL-MLLT1 (20%), or MLL-MLLT4 (7%) rearrangement was found. The most frequent rearrangement found in patients with acute myeloblastic leukemia was the MLL-MLLT3 fusion (42%), followed by MLL-MLLT10 (23%), MLL-MLLT1 (8%), MLL-ELL (8%), MLL-MLLT4 (4%), and MLL-MLLT11 (4%). In three patients, fusions involving MLL and a septin family gene (SEPT2, SEPT6, and SEPT9), were identified. The most frequently identified chromosomal rearrangements were reciprocal translocations, but insertions and deletions, some cryptic, were also observed. In our series, patients with MLL rearrangements were shown to have a poor prognosis, regardless of leukemia subtype and treatment protocol. However, patients that received a bone marrow transplant had a better survival than patients that received chemotherapy alone. Interestingly, children with 1 year or less showed a statistically significant better overall survival when compared with both older children and adults. Conclusions: The use of a combined strategy in the initial genetic evaluation of acute leukemia patients allowed us to characterize the pattern of MLL rearrangements in our institution, including our previous discovery of two novel MLL fusion partners, the SEPT2 and CT45A2 genes, and a very rare MLL-MLLT4 fusion variant. Disclosures: No relevant conflicts of interest to declare.

MLL genomic DNA Breakpoints In Infant Acute Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1350-1350
Author(s):  
Grigory Tsaur ◽  
Claus Meyer ◽  
Alexander Popov ◽  
Olga Plekhanova ◽  
Anatoly Kustanovich ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Genomic Dna ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Prognostic Significance ◽  
Chromosome 11 ◽  
Long Distance ◽  
Mll Gene ◽  
Stable Pattern ◽  
Breakpoint Location

Abstract Background Infant acute leukemia is characterized by high incidence of MLL gene rearrangements. Purpose To evaluate the distribution of MLL genomic DNA breakpoints and their relation to several diagnostic parameters among infant acute leukemia. Methods 72 infants with MLL-rearranged acute lymphoblastic leukemia (ALL) (n=52), acute myeloid leukemia (AML) (n=19) and mixed phenotype acute leukemia (n=1) were included in this study based on the availability of DNA material at diagnosis. In the observed group there were 28 boys (39%) and 44 girls (61%) with median age of 4.9 mo (range 0.03-11.9). Genomic DNA breakpoint detection in MLL gene and translocation partner genes (TPG) was performed by long-distance inverse PCR (LDI-PCR). Exon-intron numbering of MLL gene was done according to I. Nilson et al, 1996. Results Majority of ALL cases (n=28; 54%) was characterized by presence of MLL-AF4 fusion gene (FG), less frequently MLL-MLLT1 (n=12; 23%), MLL-MLLT3 (n=7; 13%) and others were found (Table 1). The most common breakpoint location within MLL gene in ALL patients was intron 11, detected in 25 cases (48%). The highest variability of MLL breakpoints was found in MLL-AF4-positive patients: only 11 of 28 (39%) had breakpoints in intron 11. The most stable pattern of MLL genomic DNA breakpoints was observed in MLL-MLLT1-positive patients: 8 of 12 (67%) had breakpoints in intron 11. In AML patients two the most prevalent FGs were MLL-MLLT3 (n=7, 37%) and MLL-MLLT10 (n=5, 26%). The remaining ones are listed in Table 1. The most frequent breakpoints location was intron 8 (8 out of 19, 42%). The most stable pattern was revealed for MLL-MLLT10 FG: MLL breakpoints in 4 of 5 (80%) cases were found in intron 9 (Table 1). ALL patients who had breakpoints in intron 11 were significantly younger (median 3.0 mo, range 0.03-11.6) than all others (median 5.6 mo, range 0.7-11.9) (p=0.025) and than patients with MLL breakpoints in intron 9 (median 6.6 mo, range 3.1-11.9) (p=0.017). For AML cases we did not find any relation between age and breakpoints locations. Distribution of MLL DNA breakpoints was similar in boys and girls and did not depend on type of TPG. Genetic recombinations involving MLL gene predominantly resulted in reciprocal chromosomal translocations (n=62; 86%). Beside them, 6 (11%) insertions were identified in all MLL-MLLT10-positive cases and MLL-SEPT6-positive one. In 11 (15%) patients we found breakpoints within the regions located from 0.7 Kb to 25.4 Kb 3' of the first exon of TPGs (MLLT1 n=9; EPS15 n=1; MYO1F n=1), however fusion transcripts at cDNA level were identified and sequenced in all these cases, indicating a spliced fusion mechanism. 3-way translocations were found in 5 patients and in 1 case we found combination of insertion with interstitial deletion of chromosome 11. The list of reciprocal genes involved in these 6 cases was as follows: CEP164, DNAH6, DCPA1, MCL1 as well as non-coding regions of 2q21.2 and 2p21. We also analyzed breakpoints in TPGs. Except above mentioned spliced fusion cases, the remaining 3 breakpoints in MLLT1 as well as 3 of 4 breakpoints in EPS15 and all breakpoints in MLLT11 were within intron 1 of corresponding genes. In AF4 the major breakpoint region included intron 3 (n=19), intron 4 (n=6) and intron 5 (n=2). We also revealed 2 rare breakpoints in intron 6 and 10. In MLLT3 the most frequent breakpoint location was intron 5 (n=12), additionally 2 cases in intron 5 were identified. In MLLT10 two separate breakpoint locations were found: intron 3 (n=1) and intron 8 (n=3) in combination with intron 9 (n=1). We estimated prognostic significance of MLL breakpoint locations in 31 cases of infant ALL treated by MLL-Baby protocol. 3-year cumulative incidence of relapse was remarkably higher in patients with breakpoints in intron 11 (n=18) in comparison to patients with breakpoint localized from intron 7 to exon 11, inclusively (n=13) (0.85±0.01 and 0.57±0.02, respectively), although difference between these two groups did not achieve statistical significance (p=0.261). Median follow-up time in the observed group was 30 months (range 6–42). Conclusion In the current study we estimated clinical and prognostic significance of MLL and TPG genomic DNA breakpoints in infant acute leukemia. Our data provide additional information of molecular genetic features of MLL-rearranged infant acute leukemia. Disclosures: No relevant conflicts of interest to declare.

Iron Metabolism before Allo-HSCT in Patients with Acute Leukemia and Impact of Iron Overload on Transplantation

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2461-2461
Author(s):  
Jimin Shi ◽  
Xuying Pei ◽  
Yi Luo ◽  
Yamin Tan ◽  
Yanmin Zhao ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Iron Overload ◽  
Iron Metabolism ◽  
Bacterial Infections ◽  
Conflicts Of Interest ◽  
Infectious Complications ◽  
Lymphocytic Leukemia ◽  
Prognostic Impact ◽  
Hematopoietic Stem ◽  
Increased Risk

Abstract Objective: Iron overload is common in patients with acute leukemia who undergoing allogenic hematopoietic stem cell transplantation (allo-HSCT). We performed a comprehensive analysis of iron parameters to assess these patients' iron metabolism, and studied the prognostic impact of pretransplant iron overload on the outcome of transplantation. Methods: In this retrospective study, we studied 124 patients undergoing myeloablative allo-HSCT between 2012 and 2014. Serum iron (SI), serum ferritin (SF), hepcidin (Hepc) and soluble transferrin receptor (sTfR) were measured before transplant. We analyzed the effect of elevated pretransplant ferritin on acute graft versus host disease (aGVHD), infectious complications, overall survival (OS) and non-relapse mortality (NRM). Results: Date of 124 patients (including 56 cases of acute lymphocytic leukemia and 68 cases of acute myeloid leukemia) were analyzed. Median SI, SF, Hepc and sTfR values were 12.15 umol/L, 667.05 ng/ml, 369.50 ng/L and 7.69 ng/ml, respectively. Iron overload (defined as SF>1000 ng/ml) were observed in 27.42% of patients. Pretransplant iron overload was significantly associated with increased risk of bacterial infections during the early post-transplant period, and with reduced risk of aGVHD. Pretransplant iron overload increased NRM and reduced OS, but there were no significant differences. Conclusion: Patients with acute leukemia regularly develop iron overload before they undergoing allo-HSCT. Pretransplant iron overload was correlated with transplantation outcome. Disclosures No relevant conflicts of interest to declare.

Cross-Species Comparison of Acquired Genetic Changes In T Cell Malignancy.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1192-1192
Author(s):  
Lynnie A. Rudner ◽  
Kim H. Brown ◽  
Kimberly P. Dobrinski ◽  
Diana F. Bradley ◽  
Jonathan Downie ◽  
...  
Keyword(s):  
T Cell ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Clinical Samples ◽  
Comparative Genomic ◽  
Genetic Changes ◽  
Time To Death ◽  
Malignant Behavior

Abstract Abstract 1192 T cell acute lymphoblastic leukemia (T-ALL) is a challenging clinical entity. Over half of adult, and about 20% of pediatric, T-ALL patients either relapse or fail to achieve remission, and despite salvage attempts outcomes are poor. To discover new acquired genetic changes that occur in T-ALL, as well as those that contribute to disease relapse, we studied zebrafish (Danio rerio) T-ALL samples using array comparative genomic hybridization (aCGH). Five different D. rerio T-ALL models have been described, and all 5 develop neoplasias that clinically and molecularly resemble human T-ALL. We performed aCGH on 14 de novo T-ALLs representing 4 of these models. To evaluate possible similarities between human and zebrafish copy number aberrations (CNAs) in T-ALL, we compared all D. rerio genes found in any CNA in our 14 zebrafish cancers to a cohort comprised of 61 published primary human T-ALLs analyzed by aCGH. In these D. rerio CNAs, we identified 764 genes with human homologues. Of these, we found significant overlap (62%) with genes in CNAs from the human T-ALL dataset. In addition, 10 genes recurrently altered (>3 samples) in zebrafish T-ALL were also seen in CNAs from 5 or more human T-ALL cases, suggesting a conserved role for these loci in T-ALL transformation across vertebrate species. In addition to studying primary T-ALL, we also conducted iterative allo-transplantations with 3 zebrafish malignancies. This technique selects for particularly aggressive disease, increasing engraftment rates and also resulting in shorter time to death of recipient animals in successive transplant rounds. Because these passaged cancers show more malignant behavior in vivo, this procedure models refractory and relapsed T-ALL. In these 3 serially-passaged cancers, 55% of the original CNAs were preserved after iterative transplantation, demonstrating the clonal relationship between the primary and passaged leukemia. In addition, 101 CNAs were acquired during passaging of the 3 T-ALLs. Genes in these loci may underlie the enhanced malignant behavior of these neoplasias. We also compared genes found in CNAs from passaged zebrafish malignancies to human aCGH results from 50 T-ALL patients who failed induction, went on to relapse, or had already relapsed. Again, many genes (n=76) were present in both datasets. Four genes altered in 2 of 3 D. rerio samples were also found in >4 cases from the human dataset. Collectively, these results suggest that zebrafish and human T-ALL are similar at the genomic level, with several homologous genes commonly gained or lost by cancers from both organisms. Genes from recurring CNAs in disease samples from both species may have particular relevance, as these candidates likely have conserved roles in T cell oncogenesis or T-ALL disease progression. As the comprehensive list of genes in CNAs from human T-ALL cases is vast and heterogeneous (comprising 15,724 unique genes from just 75 clinical samples), zebrafish T-ALL models may permit a more expedient prioritization of these candidates for further investigation. Disclosures: No relevant conflicts of interest to declare.

What Is New? An Update of the MLL Recombinome Including the Three Novel Partner Genes ABI2, PDS5A, and TOP3A

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1351-1351
Author(s):  
Claus Meyer ◽  
Mariana Emerenciano ◽  
Eva A Coenen ◽  
Eric Delabesse ◽  
Charles Herbaux ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Molecular Level ◽  
Conflicts Of Interest ◽  
Residual Disease ◽  
Patient Specific ◽  
Fusion Partner ◽  
Fusion Transcripts ◽  
Mll Gene ◽  
Diagnostic Center ◽  
Partner Gene

Abstract Abstract 1351 Chromosomal rearrangements of the MLL gene are associated with pediatric and adult de novo as well as therapy related acute myeloid leukemias, acute lymphoid leukemias, biphenotypic leukemias, and myelodysplastic syndromes. So far more than 70 MLL fusion partner genes have been characterized at the molecular level involving nearly all chromosomes. Though 11q23 rearrangements are associated with high-risk leukemias the clinical outcome of MLL rearrangements depends highly on the specific fusion partner involved. Nearly 40% of these partner genes have been identified at the Diagnostic Center of Acute Leukemia (DCAL) including the novel partner genes ABI2, PDS5A and TOP3A by analyzing more than 1400 MLL rearrangements. These rearrangements from 27 different countries include 52 different partner genes. This overview indicates all the specific introns of the translocation partner genes (TPGs) found to be involved in MLL translocations, their chromosomal locations and the type of genetic abnormality that is leading to the MLL fusion. More than 20% of all MLL rearrangements are complex ones. Within these complex rearrangements, the 5' part of the MLL gene is generally fused in frame to one of the most frequent partner genes. But the 3' part of the MLL gene is fused in many cases to a novel so-called “reciprocal MLL partner gene” like DENND4A or LRRTM4. To date more than 90 reciprocal MLL partner genes have been identified. In addition we present a recently analysed 4-way translocation where all four breakpoints could be identified by systematic breakpoint analysis using LDI-PCR. Also three novel “spliced MLL fusions”, a mechanism to generate functional chimeric fusion transcripts, involving MLLT4 (AF6), MYO1F, and CT45A2 have been identified at the DCAL. With these results, the number of genes involved in „spliced MLL fusions“ has increased from eight to eleven. Moreover we present the current breakpoint cluster region (bcr) for the 14 most frequent partner genes, namely AFF1 (AF4), MLLT3 (AF9), MLLT1 (ENL), MLLT10 (AF10), MLLT4 (AF6), ELL, EPS15, MLLT6 (AF17), SEPT6 (AF17), MLLT11 (AF1Q), SEPT9, AFF3 (LAF4), TET1, SEPT5 (PNUTL) and partial tandem duplications. For six patients, no partner gene could be identified at the molecular level and for 5 patients the identified fusion is out of frame. Unfortunetely all attemps to identify functional chimeric fusion transcripts by RACE and RT-PCR failed. These unusual MLL rearrangements probably represent a subclass of MLL abnormalities which have per se no or only a weak ability to transform hematopoeitic cells and are indentified only in the context of other hematopoeitic malignancies like the recently described MLL partner SACM1L. Finally, the determined patient-specific fusion sequences are succesfully used worldwide for minimal residual disease (MRD) monitoring to improve the treatment and outcome of acute leukemia patients. Disclosures: No relevant conflicts of interest to declare.

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