scholarly journals Clinical Value of Next Generation Sequencing in the Detection of Recurring Structural Rearrangements and Copy Number Abnormalities in Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 21-22
Author(s):  
Beth A Pitel ◽  
Neeraj Sharma ◽  
Cinthya Zepeda-Mendoza ◽  
James B Smadbeck ◽  
Kathryn E. Pearce ◽  
...  
Keyword(s):  
High Resolution ◽  
Copy Number ◽  
Myeloid Leukemia ◽  
Structural Variation ◽  
Structural Complexity ◽  
Structural Variants ◽  
Genomic Complexity ◽  
7Q Deletion ◽  
Generation Sequencing ◽  
Cytogenetic Methods

Purpose: Acute myeloid leukemia (AML) is the most common acute leukemia in adults, affecting approximately 20,000 patients annually in the United States. AML genetic subtypes, as defined by the World Health Organization (WHO), are identified through fluorescence in situ hybridization (FISH), conventional chromosome analysis, and sequencing techniques. Mate pair sequencing (MPseq) is a next generation sequencing (NGS) technology optimized to detect genome wide structural variants and copy number alterations at high resolution. Our study goal was to investigate the prognostic value of MPseq in comparison to FISH, chromosome, and sequencing studies in the evaluation of AML patients. Methods: We performed a prospective study using blood and bone marrow samples from 105 patients with a diagnosis of AML, using MPseq, along with chromosome, FISH, and NGS or PCR studies to detect small mutations. Cytogenetic and molecular genetic results were correlated with MPseq findings. We also analyzed the MPseq data for chromoplexy, chromothripsis, and progressive complexity. Junction and copy number burden, the incidence of structural variation in the genome and the percent of the genome with aberrant copy number, were evaluated. Overall survival statistics were stratified by AML subtypes and observed anomalies. Results: Although structural variants in AML were characterized at a high resolution using MPseq when compared to conventional cytogenetic methods, risk stratification using current European Leukemia Net (ELN) guidelines was not improved by MPseq. The cohorts involving 5q and/or 7q deletions exhibited high levels of genomic complexity when compared to normal karyotype AML (NK-AML). The incidence of copy number gains, losses and junctions was greatest in 5q and 7q co-deletions (5q/7q) (16.5, 25.0, 69.3) and 5q deletions (5q) (9.8, 16.7, 31.6) subtypes compared to 7q deletions (3.4, 7.0, 6.7) and NK-AML (2.6, 4.3, 3.8) (p<0.001) subtypes. Chromoplexy, chromothripsis, and progressive structural complexity were detected in most samples with 5q deletions and 5q/7q co-deletions, but absent in samples with 7q or NK-AML. Biallelic inactivation of TP53 by sequencing mutation and/or deletion was common in the 5q/7q co-deletion (14/18 cases) and 5q deletion cohorts (7/10 cases), rare in the 7q deletion cohort (1/11 cases), and absent in the NK-AML (n=44) cohort. The median OS was significantly worse for patients with 5q/7q deletions (122.5 days) and 5q deletions (248 days) compared to NK-AML (413.5 days; p<0.001 and p=0.017, respectively) and between 5q/7q deletions and 7q deletions (370.5 days; p<0.001). No significant difference was observed between 5q/7q and 5q deletion subtypes, between NK and 7q deletion subtypes and between 5q and 7q deletion subtypes. The median OS was also significantly shorter for patients with TP53 alterations compared to patients with normal TP53 status. Patients with chromoplexy, chromothripsis and/or progressive structural complexity identified by MPseq had a significantly shorter median OS compared to patients without these features. (p<0.0001) Discussion: Risk stratifications based on current guidelines using cytogenetic and sequencing results were not adjusted due to MPseq results, which is not surprising when primary abnormalities are observed by conventional cytogenetic methods. NK-AML cases did not appear to benefit from a high resolution genomic evaluation. However, MPseq added value when structural variation required additional characterization, detecting novel rearrangements, such as a KAT6A/SORBS3 fusion. Lastly, we recognized common mischaracterizations made by conventional chromosome studies - including missed TP53 deletions in 7 cases, 5q/7q deletions misinterpreted as monosomies, cryptic NUP98 rearrangements, and unappreciated genomic complexity correlating with poor OS. These mischaracterizations challenge the use of conventional chromosome studies as a gold standard without accompanying FISH or MPseq studies. MPseq, similar to other structural methodologies such as optical mapping and long read sequencing, should be considered important complements to standard cytologic techniques given the important additional genomic information obtained. The additional structural variant characterization will be critical in paving the way for genomic discovery with the overall goal of improving prognostication for patient care. Figure Disclosures Vasmatzis: WholeGenome LLC.: Other: Owner; Mayo Clinic: Membership on an entity's Board of Directors or advisory committees, Research Funding.

scholarly journals Differential Regulation of Telomeric Complex by BCR-ABL1 Kinase in Human Cellular Models of Chronic Myeloid Leukemia—From Single Cell Analysis to Next-Generation Sequencing

Genes ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1145
Author(s):  
Anna Deregowska ◽  
Monika Pepek ◽  
Katarzyna Pruszczyk ◽  
Marcin M. Machnicki ◽  
Maciej Wnuk ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Chronic Myeloid Leukemia ◽  
Telomere Length ◽  
Cell Lines ◽  
Copy Number ◽  
Myeloid Leukemia ◽  
Telomere Maintenance ◽  
Next Generation ◽  
Cellular Models ◽  
Generation Sequencing

Telomeres are specialized nucleoprotein complexes, localized at the physical ends of chromosomes, that contribute to the maintenance of genome stability. One of the features of chronic myeloid leukemia (CML) cells is a reduction in telomere length which may result in increased genomic instability and progression of the disease. Aberrant telomere maintenance in CML is not fully understood and other mechanisms such as the alternative lengthening of telomeres (ALT) are involved. In this work, we employed five BCR-ABL1-positive cell lines, namely K562, KU-812, LAMA-84, MEG-A2, and MOLM-1, commonly used in the laboratories to study the link between mutation, copy number, and expression of telomere maintenance genes with the expression, copy number, and activity of BCR-ABL1. Our results demonstrated that the copy number and expression of BCR-ABL1 are crucial for telomere lengthening. We observed a correlation between BCR-ABL1 expression and telomere length as well as shelterins upregulation. Next-generation sequencing revealed pathogenic variants and copy number alterations in major tumor suppressors, such as TP53 and CDKN2A, but not in telomere-associated genes. Taken together, we showed that BCR-ABL1 kinase expression and activity play a crucial role in the maintenance of telomeres in CML cell lines. Our results may help to validate and properly interpret results obtained by many laboratories employing these in vitro models of CML.

TP53 Alterations in Acute Myeloid Leukemia with Complex Karyotype Correlate with Specific Copy Number Alterations, Monosomal Karyotype, and Dismal Outcome,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3558-3558 ◽  
Author(s):  
Frank G. Rücker ◽  
Richard F. Schlenk ◽  
Lars Bullinger ◽  
Sabine Kayser ◽  
Veronica Teleanu ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Copy Number ◽  
Myeloid Leukemia ◽  
Multivariable Analysis ◽  
Complex Karyotype ◽  
Copy Number Alterations ◽  
Free Survival ◽  
Genomic Complexity ◽  
Monosomal Karyotype ◽  
Acute Myeloid

Abstract Abstract 3558 Acute myeloid leukemia with complex karyotype (CK-AML, CK+) is defined as ≥3 acquired chromosome abnormalities in the absence of recurrent genetic abnormalities (WHO 2008). CK-AML account for 10–15% of all AML and are characterized by a dismal outcome. To delineate prognostic markers in this unfavorable subgroup, we performed integrative analysis using genomic profiling (array-comparative genomic hybridization [CGH] and/or single-nucleotide polymorphism [SNP] analysis), as well as TP53 mutation screening in 234 CK-AML. TP53 mutations were found in 141/234 (60%) CK-AML comprising 130 missense, 21 insertion/deletion, nine nonsense, and eight splice site mutations; genomic losses of TP53 were identified in 94/234 (40%). Combining these data, TP53 alterations were detected in 70% of patients, and at least 66% of these exhibited biallelic alterations. TP53 alterations (loss and/or mutation in TP53) were characterized by a higher degree of genomic complexity, as measured by total number of copy number alterations per case (mean±SD 14.30±9.41 versus 6.16±5.53, P <.0001), and by the association with specific genomic alterations, that is, monosomy 3 or losses of 3q (-3/3q-) (P=.002), -5/5q- (P<.0001), -7/7q- (P=.001), -16/16q- (P<.0001), -18/18q- (P=.001), and -20/20q- (P=.004); gains of chromosome 1 or 1p (+1/+1p) (P=.001), +11/+11q (P=.0002), +13/+13q (P =.02), and +19/+19p (P =.04); and amplifications in 11q13∼25 [amp(11)(q13∼25)]. The recently described cytogenetic category “monosomal karyotype” (MK), defined as two or more autosomal monosomies or one single autosomal monosomy in the presence of structural abnormalities, for which a prognostic impact could be demonstrated even in CK-AML, was correlated with TP53 alterations (P <.0001). Clinically, TP53altered CK-AML patients were older (median age, 61 versus 54 years, P =.002), had lower bone marrow (BM) blast counts (median 65% versus 78%, P=. 04), and had lower complete remission (CR) rates (28% versus 50%, P =.01). For multivariable analysis, a conditional model was used with an age cut point at 60 years to address the different treatment intensities applied in the different age cohorts. In this model the only significant factors for CR achievement were TP53altered (OR, 0.55; 95%-CI, 0.30 to 1.00; P =.05) and age (OR for a 10 years difference, 0.67; 95%-CI, 0.52 to 0.87; P =.003). TP53 altered predicted for inferior survival; the 3-year estimated survival rates for CK+/TP53altered and CK+/TP53unaltered patients were as follows: event-free survival (EFS), 1% versus 13% (log-rank, P =.0007); relapse-free survival (RFS), 7% versus 30% (P =.01); and overall survival (OS), 3% versus 28% (P <.0001), respectively. Other variables predicting for inferior OS in univariable analyses were age and MK. Among the cohort of CK+/MK+ AML, TP53altered patients had a significantly worse OS (P =.0004). Multivariable analysis (stratified for age at cut point of 60 years) revealed TP53altered (HR, 2.43; 95%-CI, 1.56 to 3.77; P =.0001), logarithm of WBC (HR, 1.62; 95%-CI 1.17 to 2.26; P =.004), and age (HR for 10 years difference, 1.26; 95%-CI, 1.01 to 1.56, P =.04), but not MK as significant variables for OS. In addition, explorative subset analysis suggested that allogeneic hematopoietic stem-cell transplantation in first CR which was performed in 30 CK-AML did not impact outcome in TP53altered CK-AML. In summary, TP53 is the most frequently known altered gene in CK-AML. TP53 alterations are associated with older age, genomic complexity, specific DNA copy number alterations, MK, and dismal outcome. In multivariable analysis, TP53 alteration is the most important prognostic factor in CK-AML, outweighing all other variables, including the MK category. TP53 mutational status should be assessed in clinical trials investigating novel agents in order to identify compounds that may be effective in this subset of patients. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Clinical Impact of Copy Number Variation Revealed By Next Generation Sequencing in Acute Myeloid Leukemia

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4463-4463
Author(s):  
Kamila Janusz ◽  
Ruth Stuckey ◽  
Clara Aparicio Pérez ◽  
Cristina Bilbao ◽  
Inmaculada Fernández Camacho ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Copy Number ◽  
Myeloid Leukemia ◽  
Genetic Material ◽  
Median Number ◽  
Advisory Committees ◽  
Additional Information ◽  
Myeloid Neoplasms ◽  
Number Variation ◽  
Generation Sequencing

Abstract Introduction: Conventional karyotype analysis is one of the most important diagnostic tools to determine the prognosis of acute myeloid leukemia (AML), in which more than 50% of cases are affected. However, the low sensitivity of this technique hampers the detection of small genetic alterations like Copy Number Variation (CNV) that could affect the pathophysiology and prognosis of the disease. Current modern genomic technologies based on next generation sequencing (NGS) are capable to detect CNV at low frequencies. Objective: To analyse CNV of genes related to myeloid neoplasms profile in AML patients at diagnosis and evaluate their connection with the mutational profile, and its possible influence on the clinical-biological phenotype and prognosis of the disease. Materials and methods: The CNV and mutational profile were analysed in samples from 380 AML patients, from PLATAFO-LMA reference centres (IMIBIC, Córdoba and Dr Negrín Las Palmas de Gran Canaria) by NGS, applying a panel of 30 genes (154 regions) related to myeloid neoplasms (Sophia Myeloid Solution®) on Ilumina Myseq platform. Results: NGS detected CNV in at least one gene in 103 AML patients (27.1%). NGS detected 103 gains and 206 losses of genetic material. The median number of genes affected by CNV was 2 (range 1-12). When comparing with conventional karyotype information, CNV provided additional information in 51% of the cases. The chromosomes 7, 11 and 21 were most affected with CNV, occurring in 79 (76.7%), 40 (38.8%) and 36 (35%) patients, respectively. The gains of genetic material occurred more frequently on chromosome 21 in U2AF1 and RUNX1 genes, in 13 patients each. The loss of genetic material in EZH2 and BRAF genes occurred mutually. Interestingly, we observed the tendency that patients with CNV (loss) in NPM1 gene had shorter overall survival compared to cases with NPM1 mutated and without CNV in this gene (1 month vs. 13 months, p = 0.072) (Figure 1). Moreover CNV (loss) in TP53 gene was associated with mutations in this gene, other than deletions (p &lt;0.05). In addition, NGS detected 390 mutations distributed in 29 genes in 103 AML with CNV. The median number of mutations was 3 (range 1-10) (Figure 2). Furthermore, only 2 patients did not have any mutation in genes analysed. The distribution and frequency of genes affected by CNV and by mutations was different (Figure 3). Conclusions: The CNV of genes related to myeloid neoplasms are frequent in AML patients (27.1%) and provides additional information to the conventional karyotype in half of the cases. The loss of NPM1 gene could affect survival of AML patients. The use of NGS with CNV analysis provides important information on copy number alterations that are not detected by the karyotype, which could significantly affect the pathophysiology of AML and with potential clinical impact, especially in patients with normal karyotype. Figure 1 Figure 1. Disclosures Hernández Rivas: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees.

scholarly journals GRIDSS2: comprehensive characterisation of somatic structural variation using single breakend variants and structural variant phasing

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Daniel L. Cameron ◽  
Jonathan Baber ◽  
Charles Shale ◽  
Jose Espejo Valle-Inclan ◽  
Nicolle Besselink ◽  
...  
Keyword(s):  
Copy Number ◽  
Structural Variation ◽  
False Negative ◽  
False Negative Rate ◽  
Structural Variants ◽  
Structural Variant ◽  
Complex Rearrangement ◽  
False Discovery ◽  
Copy Number Changes ◽  
Paired End Sequencing

AbstractGRIDSS2 is the first structural variant caller to explicitly report single breakends—breakpoints in which only one side can be unambiguously determined. By treating single breakends as a fundamental genomic rearrangement signal on par with breakpoints, GRIDSS2 can explain 47% of somatic centromere copy number changes using single breakends to non-centromere sequence. On a cohort of 3782 deeply sequenced metastatic cancers, GRIDSS2 achieves an unprecedented 3.1% false negative rate and 3.3% false discovery rate and identifies a novel 32–100 bp duplication signature. GRIDSS2 simplifies complex rearrangement interpretation through phasing of structural variants with 16% of somatic calls phasable using paired-end sequencing.

scholarly journals High-Resolution Characterization of KIR Genes in a Large North American Cohort Reveals Novel Details of Structural and Sequence Diversity

2021 ◽  
Vol 12 ◽  
Author(s):  
Leonardo M. Amorim ◽  
Danillo G. Augusto ◽  
Neda Nemat-Gorgani ◽  
Gonzalo Montero-Martin ◽  
Wesley M. Marin ◽  
...  
Keyword(s):  
High Resolution ◽  
Copy Number ◽  
Structural Variation ◽  
High Throughput Sequencing ◽  
Full Range ◽  
Large Population ◽  
Killer Cell ◽  
Population Sample ◽  
Haplotype Diversity ◽  
Gene Copy

The KIR (killer-cell immunoglobulin-like receptor) region is characterized by structural variation and high sequence similarity among genes, imposing technical difficulties for analysis. We undertook the most comprehensive study to date of KIR genetic diversity in a large population sample, applying next-generation sequencing in 2,130 United States European-descendant individuals. Data were analyzed using our custom bioinformatics pipeline specifically designed to address technical obstacles in determining KIR genotypes. Precise gene copy number determination allowed us to identify a set of uncommon gene-content KIR haplotypes accounting for 5.2% of structural variation. In this cohort, KIR2DL4 is the framework gene that most varies in copy number (6.5% of all individuals). We identified phased high-resolution alleles in large multi-locus insertions and also likely founder haplotypes from which they were deleted. Additionally, we observed 250 alleles at 5-digit resolution, of which 90 have frequencies ≥1%. We found sequence patterns that were consistent with the presence of novel alleles in 398 (18.7%) individuals and contextualized multiple orphan dbSNPs within the KIR complex. We also identified a novel KIR2DL1 variant, Pro151Arg, and demonstrated by molecular dynamics that this substitution is predicted to affect interaction with HLA-C. No previous studies have fully explored the full range of structural and sequence variation of KIR as we present here. We demonstrate that pairing high-throughput sequencing with state-of-art computational tools in a large cohort permits exploration of all aspects of KIR variation including determination of population-level haplotype diversity, improving understanding of the KIR system, and providing an important reference for future studies.

High-Resolution Molecular Allelokaryotyping of Chronic Myeloid Leukemia Patients in Blast Crisis by 6.0 SNP-Arrays Shows a High-Frequency of Uniparental Disomy and Focal Copy Number Alterations Affecting the Whole Sequence or Specific Exons of Oncogenes and Tumor Suppressor Genes.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2176-2176
Author(s):  
Simona Soverini ◽  
Sabrina Colarossi ◽  
Alessandra Gnani ◽  
Fausto Castagnetti ◽  
Annalisa Astolfi ◽  
...  
Keyword(s):  
High Resolution ◽  
Tumor Suppressors ◽  
Copy Number ◽  
Myeloid Leukemia ◽  
Blast Crisis ◽  
Snp Array ◽  
Uniparental Disomy ◽  
Copy Number Alterations ◽  
Snp Arrays ◽  
Array Technology

Abstract Abstract 2176 Poster Board II-153 Progression from chronic phase to blast crisis (BC) remains a major hurdle on the road to effective treatment of chronic myeloid leukemia (CML). BC is known to be associated with accumulation of additional genetic alterations, but these alterations have so far been only partially characterized. The development of SNP-arrays as a tool for high-resolution karyotyping now allows to perform high-throughput genome-wide screens for submicroscopic genomic alterations with unprecedented informativity and resolution and to precisely map all the genes involved in these alterations. We have used Human 6.0 SNP Arrays (Affymetrix) to perform high-resolution molecular allelokaryotyping of 25 DNA samples from BC (myeloid, n=16; lymphoid, n=9) CML patients (pts). The 6.0 SNP Array technology relies on 1.8 million markers evenly spaced across the genome, with a median inter-marker distance <700 bp. Loss of Heterozygosity (LOH) analysis identified several recurrent regions of uniparental disomy (UPD) ranging from 970Kb to 2.4Mb: 3p21.31-3p21.2 (19 pts); 4p15.1 (n=18 pts); 14q23.3 (n=18 pts); 8q22.2 (n=15 pts); 7q31.31 (n=14 pts); 3q11.2 (13 pts); 17q23.2 (n=13 pts); 12q24.11-12q24.13 (n=12 pts); 15q15.2-15q15.3 (n=12 pts); 16q22.1 (n=12 pts); 10q22.1-10q22.2 (n=11 pts); 1p34.3 (n=10pts); 7q11.22 (n=10 pts); 8p11.12 (n=10 pts); 15q23-15q24.1 (n=9 pts); 20q11.22-20q11.23 (n=7 pts); 16q11.2 (n=6 pts); 17q11.2 (n=5 pts). Three pts had evidence of UPD involving the whole long arm of chromosomes 5, 14 and 19, respectively. Macroscopic copy number alterations (CNAs) (+8, +19, +14q; +21q; -7; -18, -16q; -17p; -6p; -6q; -9q) were frequent and easily detected. A variety of submicroscopic CNAs were also detected. However, we decided to exploit the unprecedented resolution power of Human 6.0 SNP Arrays and the ability of Genotyping Console 3.0.2 (Affymetrix) software to precisely pinpoint the borders of these CNAs. We thus aimed our analysis to the identification of very small CNAs that may have been missed by previous studies - all using less sensitive assays. This approach revealed a high number of focal gains or losses ranging from 4 to 47Kb, affecting single genes or even some exons only. Genes involved in >2 pts are listed in the Table below. Gains/losses mapping to known regions of copy number variation (CNV) were excluded. All the genes found to harbor CNAs were transcription factors, adaptor proteins, receptor and non-receptor kinases involved in cell proliferation and apoptosis - with a known role as oncogenes or tumor suppressors or oncogene/tumor suppressor interactors. Although these results confirm a high degrees of heterogeneity in the alterations detectable in BC CML pts, members of the RAS pathway (indicated with an asterisk) were the most frequently altered genes. Further characterization by polymerase chain reaction and sequencing is ongoing. In conclusion, the power of 6.0 SNP Array technology allowed us to detect previously unidentified alterations targeting whole or part of key oncogenes or tumor suppressors whose deregulation may play a role in determining the aggressive phenotype of BC CML, and which may represent potential therapeutic targets. Supported by European LeukemiaNet, AIL, AIRC, PRIN, Fondazione del Monte di Bologna e Ravenna. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Patterns of structural variation in human cancer

2017 ◽  
Author(s):  
Yilong Li ◽  
Nicola D Roberts ◽  
Joachim Weischenfeldt ◽  
Jeremiah A Wala ◽  
Ofer Shapira ◽  
...  
Keyword(s):  
Size Distribution ◽  
Copy Number ◽  
Structural Variation ◽  
Human Cancer ◽  
Structural Variants ◽  
Oncogenic Potential ◽  
Cancer Genomes ◽  
Rearrangement Processes ◽  
Tandem Duplications ◽  
Mutational Process

ABSTRACTA key mutational process in cancer is structural variation, in which rearrangements delete, amplify or reorder genomic segments ranging in size from kilobases to whole chromosomes. We developed methods to group, classify and describe structural variants, applied to >2,500 cancer genomes. Nine signatures of structural variation emerged. Deletions have trimodal size distribution; assort unevenly across tumour types and patients; enrich in late-replicating regions; and correlate with inversions. Tandem duplications also have trimodal size distribution, but enrich in early-replicating regions, as do unbalanced translocations. Replication-based mechanisms of rearrangement generate varied chromosomal structures with low-level copy number gains and frequent inverted rearrangements. One prominent structure consists of 1-7 templates copied from distinct regions of the genome strung together within one locus. Such ‘cycles of templated insertions’ correlate with tandem duplications, frequently activating the telomerase gene, TERT, in liver cancer. Cancers access many rearrangement processes, flexibly sculpting the genome to maximise oncogenic potential.

High-Resolution Genomic Profiling of Adult and Pediatric Core Binding Factor Acute Myeloid Leukemia Reveals New Recurrent Genomic Aberrations

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 849-849
Author(s):  
W.M. Michael Kühn ◽  
Ina Radtke ◽  
Lars Bullinger ◽  
Salil Goorha ◽  
Jinjun Cheng ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Sequence Analysis ◽  
High Resolution ◽  
Copy Number ◽  
Myeloid Leukemia ◽  
Core Binding Factor ◽  
Putative Tumor Suppressor ◽  
Binding Factor ◽  
Paired Analysis ◽  
Acute Myeloid

Abstract Abstract 849 Core-binding-factor (CBF) acute myeloid leukemia (AML) defined by the presence of t(8;21)(q22;q22) or inv(16)(p13.1q22)/t(16;16)(p13.1;q22) is associated with favorable outcome. However, about 30–40% of patients are not cured by current treatment approaches. Secondary genetic changes are believed to cause clinical heterogeneity. To identify new secondary genetic lesions, we performed high-resolution, genome-wide analysis of copy number aberrations (CNA) and copy neutral loss of heterozygosity (CN-LOH) using Affymetrix 6.0 single nucleotide polymorphism (SNP) microarrays in 300 adult and pediatric CBF AMLs; t(8;21), n=157 (adult, n=114; pediatric, n=43); and inv(16), n=143 (adult, n=104; pediatric, n=39). Germline control DNA from remission bone marrow or peripheral blood was available for paired analysis in 175 patients. In addition, for 42 patients matched relapse samples were analyzed. Data were processed using reference alignment, dChipSNP and circular binary segmentation. Paired analysis revealed a median of 1.28 somatic CNAs per case [t(8;21): 1.14, range: 0–5; inv(16): 1.45, range: 0–9], with deletions more common than gains [t(8;21): 0.94 losses/case vs. 0.2 gains/case; inv(16): 0.95 vs. 0.5]. Recurrent deletions were detected at chromosomal bands 7q36.1 (n=23), 9q21.13 (n=15), 11p13 (n=7), 17q11.2 (n=6), 10q24.32 (n=2), and at the chromosomal breakpoints of t(8;21) and inv(16) on 8q21.3 (n=9), 21q22 (n=16), 16p13.11 (n=28), and 16q22.11 (n=21). Deletions at 7q, 11p and 17q were validated using FISH analysis. Minimally deleted regions (MDR) less than 1.5 Mb were identified at 7q36.1 (647 Kb, 4 genes), 9q21.13 (1125 Kb, 9 genes), 11p13 (130 Kb, 1 gene), and 17q11.2 (902 Kb, 11 genes), with each region containing a putative tumor suppressor (e.g., MLL3 on 7q, FRMD3 on 9q, WT1 on 11p, and NF1 on 17q). Sequence analysis of MLL3 in 23 cases with del(7q), 1 case with 7q CN-LOH, and 23 randomly selected cases identified a MLL3 truncating mutation leading to a premature stop codon in a case that lacked a 7q alteration. The del(11p13) contained only WT1 and primarily affected inv(16)-cases (5 of 7). Sequence analysis of WT1 in four cases with del(11p) revealed an additional frame shift mutation in the remaining allele in one case. Sequence analysis of WT1 in an additional 103 inv(16)-containing cases revealed mutations in 10 (9%) of the cases. The MDR at 17q11.2 was exclusively identified in inv(16)-containing cases (n=6) and included the tumor supressor NF1. Sequence analysis of all coding exons in NF1 in 4 additional inv(16)-containing AMLs revealed no additional mutation. Recurrent gains were identified at 22q11.21-q13.33 (n=20; 32 Mb), 8q24.21 (n=14; 138 Kb), 13q21.1-q34 (n=6; 14 Mb), and 11q25 (n=5; 368 Kb). The smallest gains were identified at 8q24.21 and 11q25, both containing only a single non-coding RNA gene (CCDC26 and LOC283177, respectively). Somatic CN-LOH were uncommon and only found at 1p36.33-p12 (n=2), 4q (n=2), and 19p (n=2). In a comparative analysis of paired diagnostic and relapse samples, novel CNAs at the time of relapse were identified at 3q13.31 (n=5), 5q (n=2), 17p (n=2), and 17q (n=2). The MDR at 3q was only 46 kb in size and contains a single transcript that has been connected to LSAMP, a putative tumor suppressor located 404 Kb upstream of the deletion. In summary, our data provide a comprehensive profiling of copy number alterations in pediatric and adult CBF AML. These data demonstrate a very low number of CNAs, with no significant differences noted between pediatric and adult cases. Interestingly, a number of novel recurrent secondary genetic alterations are identified. Exploring the biological role of these lesions in leukemogenesis and drug resistance should provide important insights into the CBF leukemias. Disclosures: No relevant conflicts of interest to declare.

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