Philadelphia Chromosome In Patients Research Articles

Novel Fusion Genes at CML Diagnosis Reveal a Complex Pattern of Genomic Rearrangements and Sequence Inversions Associated with the Philadelphia Chromosome in Patients with Early Blast Crisis

IntroductionThe emergence of next generation RNA sequencing (RNA-Seq) technologies will likely advance diagnostic, prognostic and therapeutic strategies for patients (pts) with various cancers.Novel fusions have recently been described in AML and solid tumors using RNA-Seq, and many were out-of-frame.It is not known whether novel fusions are generated at diagnosis (Dx) of CML and if so, their impact on treatment outcome. We used RNA-Seq coupled with whole exome sequencing to identify and characterize novel fusions at Dx of CML and at blast crisis (BC). A highly complex pattern of genomic rearrangements of chromosome (chr) 9 and 22 was found in some pts at Dx that generated novel fusions associated with multiple genomic breaks, multiple non-contiguous deletionsand inversion of genomic sequences, including BCR and ABL.MethodRNA-Seqwas performed on Dx samples of chronic phase pts treated with first line TKI representing 2 extreme response groups: 14 pts with BC at a median of 6 months (mos), range 3-25 (group A, poor response), and 16 pts with rapid major molecular response by 3mosof imatinib (group B, optimal response). RNA-Seqwas also performed for 9 of 14 pts at BC (group C).The TruSeq Stranded Total RNA-RiboZero Gold Sample Prep Kit (Illumina) was used. This method enables computation of transcription direction and detection of genomic breaks from precursor RNA. Fusions were identified usingthe STAR algorithm and those detected in 4 normal controls were filtered out. Fusions with a high unique read count, supporting genomic breaks or detection atDxand BC for individual pts were prioritized for validation and their somatic status confirmed by RT-PCR.Correspondingwhole exome sequencingwas conducted for 30 samples. Copy number variation was detected usingSequenzaand exon level resolution ofdeletionswas achieved using an in-house sequence read normalization method.ResultsBCR-ABL fusions were detected by RNA-Seq in 29/30 pts at Dx and all pts at BC. In addition, novel fusions were identified in eachptgroup.GroupA(poor response). AtDx, 8 cytogenetically cryptic novel fusion transcripts were detected in 4/14 pts, Fig A pts1-4. All fusions involved genes or sequences onchr9 and/or 22 and all 4 pts had concomitant genomic inversion events. Fusion partners included inverted ABL intronic sequences and an inverted intergenic region on chr 22, potentially derived from the generation and activation of cryptic splice sites. BCR was a frequent fusion partner (5/8 fusion transcripts). Genomicdeletionswere detected adjacent to some fusions (3deletionsin 1pt),indicatingdeletionsmay have contributed to fusion formation, Fig B. All 4 pts with novel fusions and inversions had very rapid BC (within 5mosofDx).Group B (optimal response).AtDx, only 1/16 pts had a fusion detected in addition to BCR-ABL: TNRC6B (chr22)-NEK6 (chr9), Fig Apt5. Thisptalso had multiple non-contiguousdeletions: 2 each onchr9 and 22 associated with fusion formation, but no inversions, Fig B.Group C (BC). At BC, 3/9 pts gained fusions. No inversions were detected. Two pts had MLL fusions; MLL-BCAT1 (novel) and MLL-MLLT6. The MLL gene is a known fusion partner in acute leukemia, associated with poor prognosis. Both pts had sudden onset BC after a complete cytogenetic response. These fusions were supported by translocation events detected by cytogenetic analysis;t(11;12)(q23;p12) and t(11;17)(q23;q21). The thirdptgained an out-of-frame ANKRD11-UBQLN1 fusion at BC. Indeed, ANKRD11 expression was reduced by 3-fold at BC. Interestingly, thispthad a germline gain of function TP53 mutation. ANKRD11 is a p53 coactivator and loss of expression defined poor prognosis in breast cancer pts that harbored gain of function p53 mutations (Noll, 2012). The ANKRD11 fusion detected at BC in CML may have been selected with disease progression in the context of mutant p53.ConclusionWe identified a subset of pts with novel fusions and inversion events at Dx involvingchr9 and 22. These inversions were detected among the pts studied with very rapid BC. The biological effects of the novel fusions remain to be determined. Our data support the presence of novel fusions, additional to BCR-ABL in CML and add a further layer of genetic heterogeneity associated with the Philadelphia translocation. Whether genomic inversions identify a small subset of CML pts with very poor prognosis requires expanded analysis. [Display omitted] DisclosuresYeung:BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Research Funding. Mueller:Ariad: Honoraria; Institute for Hematology and Oncology GmbH: Employment; Bristol-Myers Squibb: Honoraria; Novartis: Honoraria; Pfizer: Honoraria. Dietz:Institute for Hematology and Oncology GmbH: Employment. Ross:Novartis Pharmaceuticals: Honoraria, Research Funding; BMS: Honoraria. Hughes:Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Branford:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Research Funding; Bristol Myers Squibb: Research Funding; Qiagen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cepheid: Consultancy.

Small Molecule ErbB Inhibitors Decrease Proliferative Signaling and Promote Apoptosis in Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia

The presence of the Philadelphia chromosome in patients with acute lymphoblastic leukemia (Ph+ALL) is a negative prognostic indicator. Tyrosine kinase inhibitors (TKI) that target BCR/ABL, such as imatinib, have improved treatment of Ph+ALL and are generally incorporated into induction regimens. This approach has improved clinical responses, but molecular remissions are seen in less than 50% of patients leaving few treatment options in the event of relapse. Thus, identification of additional targets for therapeutic intervention has potential to improve outcomes for Ph+ALL. The human epidermal growth factor receptor 2 (ErbB2) is expressed in ∼30% of B-ALLs, and numerous small molecule inhibitors are available to prevent its activation. We analyzed a cohort of 129 ALL patient samples using reverse phase protein array (RPPA) with ErbB2 and phospho-ErbB2 antibodies and found that activity of ErbB2 was elevated in 56% of Ph+ALL as compared to just 4.8% of Ph−ALL. In two human Ph+ALL cell lines, inhibition of ErbB kinase activity with canertinib resulted in a dose-dependent decrease in the phosphorylation of an ErbB kinase signaling target p70S6-kinase T389 (by 60% in Z119 and 39% in Z181 cells at 3 µM). Downstream, phosphorylation of S6-kinase was also diminished in both cell lines in a dose-dependent manner (by 91% in both cell lines at 3 µM). Canertinib treatment increased expression of the pro-apoptotic protein Bim by as much as 144% in Z119 cells and 49% in Z181 cells, and further produced caspase-3 activation and consequent apoptotic cell death. Both canertinib and the FDA-approved ErbB1/2-directed TKI lapatinib abrogated proliferation and increased sensitivity to BCR/ABL-directed TKIs at clinically relevant doses. Our results suggest that ErbB signaling is an additional molecular target in Ph+ALL and encourage the development of clinical strategies combining ErbB and BCR/ABL kinase inhibitors for this subset of ALL patients.

Detection of Philadelphia Chromosome in Patients with Chronic Myeloid Leukemia from the Prešov Region in Slovakia (1995-2004)

Detection of Philadelphia Chromosome in Patients with Chronic Myeloid Leukemia from the Prešov Region in Slovakia (1995-2004)

Detection of Philadelphia Chromosome in Patients with Chronic Myeloid Leukemia from the Prešov Region in Slovakia (1995-2004)

Philadelphia chromosome (Ph) is a characteristic chromosomal marker that is associated with chronic myelogenous leukemia (CML). Philadelphia chromosome in bone marrow cells in patients with suspected diagnosis of CML in the Presov region (1995-2004) was detected in 94.4 % of cases. In one patient a complex translocation involving the chromosomes 8, 9 and 22 was identified. One patient has showed extra numerical and structural chromosomal aberrations. The mosaic karyotype of Ph chromosome was found in 5.9 % of cases. The conventional cytogenetic analysis remains the standard method for the purpose of diagnosis and monitoring of the therapeutic response and minimal residual disease in patients with chronic myeloid leukemia (Tab. 1, Fig. 1, Ref. 18). Full Text (Free, PDF) www.bmj.sk.

Aberrant DNA Methylation of the Src Tyrosine Kinase Hck Is a Frequent Event in Human Leukemia and May Predict for Poor Prognosis in Adult Acute Lymphocytic Leukemia (ALL).

Aberrant DNA methylation of promoter-associated CpG islands is a frequent phenomenon in human leukemias, and in particular in adult ALL. Hck is a member of the Src family of tyrosine kinases, and functionally is located downstream of BCR-ABL signaling in chronic myelogenous leukemia (CML). Hck expression is limitedly to myeloid cells and B cell lymphocytes. Although some evidence indicates that Hck is required for malignant transformation and apoptosis, its role in leukemia is not fully understood. Here we analyze the role of aberrant DNA methylation of Hck in leukemia cell lines and patients. Using BLAT, we first identified the presence of a canonical CpG island in the near proximity of the transcription start site of HcK. To detect and measure DNA methylation, we designed a combined bisulfite restriction PCR assay. Using this assay, we found that Hck was methylated in 13 out of 23 hematopoietic and 8 out of 10 non-hematopoietic cell lines, but not in the bone marrow from 6 healthy individuals. We subsequently studied Hck expression by real-time PCR using GAPDH expression as an internal control. Hck expression was lower (dCT = −14.2± 3.6) in 7 Hck methylated cell lines than in 8 Hck unmethylated ones (dCT= −9.0± 3.5), p=0.017. All the cell lines studied were of myeloid or B cell origin. We then treated the Raji cell line with the hypomethylating agent 5-aza-2-deoxycytidine (DAC). DAC treatment resulted in partial hypomethylation of Hck and in an increment of Hck expression (dCT: −19.37 to −8.47). Subsequently, the effects of DAC treatment on Hck protein expression levels were analyzed using Western blot. These experiments showed a strong correlation between hypomethylation, gene re-expression and protein expression levels. These data therefore indicates that DNA methylation is an important aberrant regulator of Hck expression in leukemia cell lines. Based on the relevance of these findings, we then analyzed the frequency of Hck methylation in patients with leukemia. Using a cut-off of 10%, Hck was found to be methylated in 15 out of 44 (34%) patients with ALL, 9 out 23 pts (39%) with CML, and 3 out 10 pts (30%) with AML. Of importance, the density of Hck methylation was significantly higher in patients with ALL (mean 11.3%; range 0–76) compared to those with CML(5.2%; range 0–12) or AML ( 7.5%, range 0–14), p=0.02. Hck methylation was not associated with a B cell phenotype or the presence of the Philadelphia chromosome in patients with ALL. Nine ALL pts out of 15 with Hck methylation had died compared to 7 out 29 unmethylated (total ALL group n=34). Median survival had not been reached for the group of patients with no Hck methylation (n=29) compared to 116 weeks for those with Hck methylation (n=15) (p=0.08). All pts had been treated with hyperCVAD based chemotherapy. These data indicates that Hck methylation is a frequent phenomenon in human leukemia that maybe associated with a worse prognosis in ALL and suggests that Hck has a tumor suppressor like function in these disorders.

Coexistence of Inversion 16 and the Philadelphia Chromosome in Patients with Acute Myelogenous Leukemia

The coexistence of the Philadelphia chromosome and inversion 16 abnormality in de novo acute myelogenous leukemia (AML) has only rarely been reported. We report the case of a 23-year-old man with these cytogenetic abnormalities. He is in a durable remission following intensive chemotherapy. The literature on this subject is reviewed.

Molecular cytogenetics in cancer

Since identification of the Philadelphia-chromosome in patients with chronic myeloid leukaemia,1,2 more than 25 000 cases of haematological cancers and 11 000 cases of solid tumours have been karyotyped and reported by July, 2000.3 Recurrent and characteristic chromosome abnormalities, commonly of major diagnostic and prognostic importance, have been observed in many malignant tumours.

Використання молекулярно-біологічних методів для виявлення філадельфійської хромосоми у хворих на лейкози

Використання молекулярно-біологічних методів для виявлення філадельфійської хромосоми у хворих на лейкози

Development of a sensitive, highly controlled assay for molecular detection of the Philadelphia chromosome in patients with chronic myelogenous leukemia

The Philadelphia chromosome (Ph1), present in ⩾95% of chronic myelogenous leukemia (CML) patients, is a well-characterized translocation that results in a unique chimeric gene product ( BCR/ABL) with transforming capability. Molecular methods utilizing the polymerase chain reaction (PCR) to detect BCR/ABL mRNA transcripts has been useful for detecting minimal residual disease (MRD) after treatment, as well as for establishing the diagnosis of CML. Amplification-based assays for the BCR/ABL transcript, however, have shown variable reproducibility and sensitivity. This variability may be largely due to technical differences and insufficient controls. In this report, we describe the development of a highly controlled, reproducible, and sensitive PCR assay to detect Ph1 that is well suited to clinical and research applications. A validation study of 82 samples was performed consisting of 25 dilutions of K562 cells (Ph1+) into normal cultured B cells, 26 pre- and post-transplant peripheral blood samples from CML patients, 16 peripheral blood samples for diagnosis of CML, and 15 peripheral blood samples from healthy individuals. RNA isolated from 3 to 5 million leukocytes was reverse transcribed (RT) and amplified by nested primer PCR. The products were characterized using agarose gel electrophoresis. Approximately 1000 Ph1-positive cells admixed with 10 6 normal cells were detectable after one round of amplification. In 60% of assays where one Ph1-positive cell was admixed with 10 6 normal cells, a BCR/ABL product was detectable after nested primer PCR. Specific measures to ensure accurate results in routine testing included (a) assessing RNA integrity and adequate cDNA preparation by detection of the constitutively expressed ABL mRNA, (b) monitoring sensitivity with the addition and detection of K562 RNA mixed with RNA from unknown samples (failure to detect the “spiked” K562 RNA indicates the presence of inhibitors or ribonucleases within the unknown RNA sample), (c) detection of nucleic acid contaminants by using negative controls in every assay, and (d) duplicate analysis of all samples and controls. Internally, this assay was 100% reproducible. Our results verify that nested primer RT-PCR is a fast, sensitive alternative to cytogenetic or Southern blot analysis for monitoring MRD after treatment and for diagnosis of CML. In addition, the highly controlled detection scheme presented here can be used as a general model for the development of other amplification-based detection assays.

Molecular analysis of interferon-induced suppression of Philadelphia chromosome in patients with chronic myeloid leukemia

Treatment with recombinant human interferon alpha-A (Roferon-A) is associated with stable suppression of the population of cells that display the Philadelphia (Ph1) chromosome in some patients with chronic myelogenous leukemia (CML) as defined by cytogenetic analysis. Southern blot analyses employing a 3′ breakpoint cluster region (bcr) probe (Pr- 1) were performed to confirm a complete suppression of the Ph1+ chromosome-positive clone of cells at the DNA level. The complete disappearance of rearranged restriction fragments of the bcr gene, which were a characteristic of the disease prior to Roferon-A therapy, was accompanied by the restoration of normal bone marrow and achievement of durable ongoing complete remission for 9 and 6 months, respectively, in two patients with Philadelphia-positive (Ph1+) CML. Molecular analysis is a valuable probe for monitoring the clinical course of disease in patients with Ph1+ CML.

Molecular Analysis of Interferon-Induced Suppression of Philadelphia Chromosome in Patients With Chronic Myeloid Leukemia

Treatment with recombinant human interferon alpha-A (Roferon-A) is associated with stable suppression of the population of cells that display the Philadelphia (Ph1) chromosome in some patients with chronic myelogenous leukemia (CML) as defined by cytogenetic analysis. Southern blot analyses employing a 3' breakpoint cluster region (bcr) probe (Pr-1) were performed to confirm a complete suppression of the Ph1+ chromosome-positive clone of cells at the DNA level. The complete disappearance of rearranged restriction fragments of the bcr gene, which were a characteristic of the disease prior to Roferon-A therapy, was accompanied by the restoration of normal bone marrow and achievement of durable ongoing complete remission for 9 and 6 months, respectively, in two patients with Philadelphia-positive (Ph1+) CML. Molecular analysis is a valuable probe for monitoring the clinical course of disease in patients with Ph1+ CML.

The Distribution of the Philadelphia Chromosome in Patients with Chronic Myelogenous Leukemia

Abstract Thirteen patients with chronic myelogenous leukemia continued to have the Ph1 chromosomes in 90-100 per cent dividing marrow cells during drug-induced clinical remissions. The Ph1 chromosome was present in erythroid as well as granulocytic marrow cells, and possibly in megakaryocytes. The presence of Ph1 chromosomes was also studied in cultures of peripheral blood. In six patients in relapse, 40 per cent of metaphases contained the Ph1 chromosome, and the percentage of these cells corresponded roughly to the relative frequency of immature granulocytes in the blood. In contrast, during remission, few or no Ph1 chromosomes were found in peripheral blood cultures, presumably because in the absence of immature granulocytes the dividing cells in the cultures originate from lymphocytes, as they do in normal blood. It is suggested that the Ph1 chromosome usually arises in a precursor cell common to the erythroid, granulocytic, and megakaryocytic, but not the lymphoid series of hemopoietic cells.