Search

Fusion genes involving MEF2D have recently been identified in precursor B-cell acute lymphoblastic leukemia, mutually exclusive of the common risk stratifying genetic abnormalities, although their true incidence and associated clinical characteristics remain unknown. We identified 16 cases of acute lymphoblastic leukemia and 1 of lymphoma harboring MEF2D fusions, including MEF2D-BCL9 (n=10), MEF2D-HNRNPUL1 (n=6), and one novel MEF2D-HNRNPH1 fusion. The incidence of MEF2D fusions overall was 2.4% among consecutive precursor B-cell acute lymphoblastic leukemia patients enrolled onto a single clinical trial. They frequently showed a cytoplasmic μ chain-positive pre-B immunophenotype, and often expressed an aberrant CD5 antigen. Besides up- and down-regulation of HDAC9 and MEF2C , elevated GATA3 expression was also a characteristic feature of MEF2D fusion-positive patients. Mutations of PHF6 , recurrent in T-cell acute lymphoblastic leukemia, also showed an unexpectedly high frequency (50%) in these patients. MEF2D fusion-positive patients were older (median age 9 years) with elevated WBC counts (median: 27,300/ml) at presentation and, as a result, were mostly classified as NCI high risk. Although they responded well to steroid treatment, MEF2D fusion-positive patients showed a significantly worse outcome, with 53.3% relapse and subsequent death. Stem cell transplantation was ineffective as salvage therapy. Interestingly, relapse was frequently associated with the presence of CDKN2A/CDKN2B gene deletions. Our observations indicate that MEF2D fusions comprise a distinct subgroup of precursor B-cell acute lymphoblastic leukemia with a characteristic immunophenotype and gene expression signature, associated with distinct clinical features., (Copyright© 2019 Ferrata Storti Foundation.)

Fluorescent in situ hybridization (FISH) analysis is the standard methods for screening ABL1 fusions, which is recurrently translocated in pediatric acute lymphoblastic leukemia (ALL), and potentially targetable by kinase inhibitors. Here we demonstrated a case of B-cell precursor ALL with NUP214-ABL1 fusion, which break-apart FISH assay for ABL1 failed to detect. The cryptic fusion was generated by small duplication from ABL1 to NUP214, which was detected by copy number analysis using genomic microarray and confirmed by PCR. In the context of precision medicine, we should establish how to screen targetable abnormalities for minimizing risk of false-negative.

The survival rate of children with acute lymphoblastic leukemia (ALL) has increased to approximately 90% after substantial progress in risk-oriented treatment strategies. Between 2005 and 2013, the Tokyo Children's Cancer Study Group (TCCSG) conducted a risk-oriented, non-randomized study, L04-16. The principal aim of this study was to assemble background characteristics and treatment outcomes, and gather genetic information on leukemic cells under central diagnosis. This report outlines the background characteristics and treatment outcomes of 1033 children with ALL treated according to a TCCSG platform. The 5-year event-free and overall survival (OS) rates for all children were 78.1 ± 1.3 and 89.6 ± 1.0%, respectively. The OS rate was significantly higher in children with B-cell precursor (BCP)-ALL (91.9 ± 1.0%, n = 916) than in those with T-ALL (71.9 ± 4.3%, n = 117, p < 0.001). In univariate analysis for BCP-ALL, children aged 1-6 years (5y-OS: 94.2 ± 1.0%), with an initial white blood cell count of < 20,000/μL (94.0 ± 1.0%), high hyperdiploidy (95.4 ± 1.6%), ETV6-RUNX1 (97.4 ± 1.2%) or TCF3-PBX1 (96.9 ± 2.1%), and "Day8NoBlasts" (96.4 ± 1.1%) had the best outcomes. Genetic investigation revealed two novel fusion genes within this cohort: ETV6-ZNF385A and ZNF362-TCF4. Our study highlighted the clinical aspects of genomic features of ALL in Japanese children. We provide fundamental information for the further molecular investigation of this disease.

Previous studies have reported several cases of juvenile myelomonocytic leukemia (JMML) developing blastic transformation during an indolent clinical course, but the underlying mechanism of transformation is still not well understood. In this report, we describe a case of JMML with blastic transformation possibly caused by additional copy number gains of the KRAS mutant allele. We have discovered that the copy number gain of the mutant allele is an additional possible cause of blastic transformation in JMML., (© 2017 Wiley Periodicals, Inc.)

Intragenic PAX5 amplification defines a novel, relapse-prone subtype of B-cell precursor acute lymphoblastic leukemia with a poor outcome., Competing Interests: Conflict-of-interest disclosure: The authors declare no competing financial interests.

ZNF384-related fusion genes are associated with a distinct subgroup of B-cell precursor acute lymphoblastic leukemias in childhood, with a frequency of approximately 3-4%. We previously identified a novel EP300-ZNF384 fusion gene. Patients with the ZNF384-related fusion gene exhibit a hematopoietic stem cell (HSC) gene expression signature and characteristic immunophenotype with negative or low expression of CD10 and aberrant expression of myeloid antigens, such as CD33 and CD13. However, the molecular basis of this pathogenesis remains completely unknown. In the present study, we examined the biological effects of EP300-ZNF384 expression induced by retrovirus-mediated gene transduction in an REH B-cell precursor acute lymphoblastic leukemia cell line, and observed the acquisition of the HSC gene expression signature and an up-regulation of GATA3 gene expression, as assessed by microarray analysis. In contrast, the gene expression profile induced by wild-type ZNF384 in REH cells was significantly different from that by EP300-ZNF384 expression. Together with the results of reporter assays, which revealed the enhancement of GATA3-promoter activity by EP300-ZNF384 expression, these findings suggest that EP300-ZNF384 mediates GATA3 gene expression and may be involved in the acquisition of the HSC gene expression signature and characteristic immunophenotype in B-cell precursor acute lymphoblastic leukemia cells.

Follicular lymphoma (FL) is quite rare in children. There have been only two major reports on pediatric FL. The present retrospective study on pediatric FL in Japan, including FL with diffuse large B cell lymphoma (DLBCL), analyzed data from 1991 to 2014. Twenty-two patients with pediatric FL were analyzed. Sixteen patients were boys and six were girls. Median age of onset was 9 years (range 4-17 years). In 11 patients, DLBCL co-existed with FL. The initial lesions involved cervical lesions in 16 patients, and the abdomen in six. With regard to stage of disease at diagnosis, 17 patients were at stage I or II, four were at stage III, and one was at stage IV. Chemotherapy was administered in 18 patients, and only resection was performed in four patients. Mature B lymphoma regimens were selected for 17 patients who received chemotherapy. Although two patients relapsed, all patients are currently alive and disease free. The median follow-up period was 54.5 months (range 6-126 months). Patients having FL with DLBCL were younger compared with those having FL, and this disease was more frequently observed in female patients. Our data revealed that FL in Japanese children is a tumor with good prognosis, as in reports from the United States and Europe.

Fusion genes involving ZNF384 have recently been identified in B-cell precursor acute lymphoblastic leukemia, and 7 fusion partners have been reported. We further characterized this type of fusion gene by whole transcriptome sequencing and/or polymerase chain reaction. In addition to previously reported genes, we identified BMP2K as a novel fusion partner for ZNF384 Including the EP300-ZNF384 that we reported recently, the total frequency of ZNF384-related fusion genes was 4.1% in 291 B-cell precursor acute lymphoblastic leukemia patients enrolled in a single clinical trial, and TCF3-ZNF384 was the most recurrent, with a frequency of 2.4%. The characteristic immunophenotype of weak CD10 and aberrant CD13 and/or CD33 expression was revealed to be a common feature of the leukemic cells harboring ZNF384-related fusion genes. The signature gene expression profile in TCF3-ZNF384-positive patients was enriched in hematopoietic stem cell features and related to that of EP300-ZNF384-positive patients, but was significantly distinct from that of TCF3-PBX1-positive and ZNF384-fusion-negative patients. However, clinical features of TCF3-ZNF384-positive patients are markedly different from those of EP300-ZNF384-positive patients, exhibiting higher cell counts and a younger age at presentation. TCF3-ZNF384-positive patients revealed a significantly poorer steroid response and a higher frequency of relapse, and the additional activating mutations in RAS signaling pathway genes were detected by whole exome analysis in some of the cases. Our observations indicate that ZNF384-related fusion genes consist of a distinct subgroup of B-cell precursor acute lymphoblastic leukemia with a characteristic immunophenotype, while the clinical features depend on the functional properties of individual fusion partners., (Copyright© Ferrata Storti Foundation.)

Background: LMB chemotherapy based on the FAB LMB96 study is internationally accepted as one of the standard treatments for pediatric B-cell non-Hodgkin lymphoma (B-NHL), though experience with this regimen in Japan is very limited. Since 2009, we have administered LMB chemotherapy to children with B-NHL at the National Center for Child Health and Development. Thus, we herein report the clinical characteristics and outcomes of 13 children with B-NHL given LMB chemotherapy., Results: Median age was 7.5 years. Five patients were girls and 8 were boys. Nine were subclassified as having Burkitt lymphoma and 4 as having diffuse large B-cell lymphoma. According to the St. Jude staging system, 3, 4, 2, 1, and 3 patients had stages 1, 2, 3, 4, and B-ALL disease, respectively. According to the LMB group classification system, nine patients were classified into Group B and four into Group C. At a median follow-up of 2.3 years, all patients are alive without lymphoma relapse. In Group C, myelosuppression and severe mucositis were the main adverse events especially during induction therapy. High-dose methotrexate at a dose of 8 g/m2 was manageable using standard supportive therapy even with 24-hour infusion., Conclusion: Our experience indicates the feasibility of LMB chemotherapy for Japanese children with B-NHL.

Recent reports described the NUP98-NSD1 fusion as an adverse prognostic marker for acute myeloid leukaemia (AML) and PRDM16 (also known as MEL1) as the representative overexpressed gene in patients harbouring NUP98-NSD1 fusion. PRDM16 gene expression levels were measured via real-time polymerase chain reaction in 369 paediatric patients with de novo AML, of whom 84 (23%) exhibited PRDM16 overexpression (PRDM16/ABL1 ratio ≥0·010). The frequencies of patients with high or low PRDM16 expression differed widely with respect to each genetic alteration, as follows: t(8;21), 4% vs. 96%, P < 0·001; inv(16), 0% vs. 100%, P < 0·001; KMT2A (also termed MLL)- partial tandem duplication, 100% vs. 0%, P < 0·001; NUP98-NSD1, 100% vs. 0%, P < 0·001. The overall survival (OS) and event-free survival (EFS) among PRDM16-overexpressing patients were significantly worse than in patients with low PRDM16 expression (3-year OS: 51% vs. 81%, P < 0·001, 3-year EFS: 32% vs. 64%, P < 0·001) irrespective of other cytogenetic alterations except for NPM1. PRDM16 gene expression was particularly useful for stratifying FLT3-internal tandem duplication-positive AML patients (3-year OS: high = 30% vs. low = 70%, P < 0·001). PRDM16 overexpression was highly recurrent in de novo paediatric AML patients with high/intermediate-risk cytogenetic profiles and was independently associated with an adverse outcome., (© 2015 John Wiley & Sons Ltd.)

Mutations in the colony-stimulating factor 3 receptor (CSF3R) and calreticulin (CALR) genes have been reported in a proportion of adults with myeloproliferative disease. However, little is known about CSF3R or CALR mutations in paediatric myeloid disorders. We analysed CSF3R exons 14 and 17, and CALR exon 9, using direct sequencing in samples of paediatric acute myeloid leukaemia (AML; n = 521), juvenile myelomonocytic leukaemia (JMML; n = 40), myelodysplastic syndrome (MDS; n = 20) and essential thrombocythaemia (ET; n = 21). CSF3R mutations were found in 10 (1.2%) of 521 patients with AML; two in exon 14 (both missense mutations resulting in p.T618I) and eight in exon 17 (three frameshift mutations: p.S715X, p.Q774R, and p.S783Q; and five novel missense mutations: p.Q754K, p.R769H, p.L777F, p.T781I, and S795R). All of the patients with mutations in CSF3R exon 17 had chromosomal translocations, including four with t(8;21). At the time of reporting, seven of these ten patients are alive; three have died, due to side effects of chemotherapy. No CSF3R mutations were found in cases of MDS, JMML or ET. The only mutation found in the CALR gene was a frameshift (p.L367 fs) in one ET patient. We discuss the potential impact of these findings for the leukaemogenesis and clinical features of paediatric myeloid disorders., (© 2015 John Wiley & Sons Ltd.)

Malignant rhabdoid tumor (MRT) is a rare and highly lethal cancer that mainly affects infants and young children. The majority of MRT are characterized by loss of function of SMARCB1 on chromosome 22q11.2. However, little is known about genetic changes other than SMARCB1 alterations that are responsible for the development and/or progression of MRT. To explore additional gene targets in MRT, we analyzed 21 MRT specimens (12 fresh tumors and 9 MRT-derived cell lines) using high-density single nucleotide polymorphism genotyping microarrays. Although MRT genomes are characterized by common 22q11.2 deletions, affecting the SMARCB1 locus with a frequency of 95.2% (20/21 specimens), other genetic changes have been less frequent. Of the 20 specimens with deletions of 22q11.2, eight specimens showed uniparental disomy of the SMARCB1 locus with homozygous deletions or gene mutations. High-resolution analysis also disclosed the recurrent hemizygous/homozygous deletions of 7q35-q36.1, involving the CNTNAP2 locus in three specimens. Mutations analysis of CNTNAP2 showed a novel R157C missense mutation in a primary case, and methylation analysis showed recurrent hypermethylation of CNTNAP2 in three of nine cell lines. These results demonstrated that CNTNAP2 is one of the additional gene targets, other than SMARCB1, in MRT., (© 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.)

Aim: To investigate the factors other than fibrosis stage correlating with acoustic radiation force impulse (ARFI) elastograpy in chronic hepatitis C., Methods: ARFI elastograpy was performed in 108 consecutive patients with chronic hepatitis C who underwent a liver biopsy. The proportion of fibrosis area in the biopsy specimens was measured by computer-assisted morphometric image analysis., Results: ARFI correlated significantly with fibrosis stage (β = 0.1865, P < 0.0001) and hyaluronic acid levels (β = 0.0008, P = 0.0039) in all patients by multiple regression analysis. Fibrosis area correlated significantly with ARFI by Spearman's rank correlation test but not by multiple regression analysis. ARFI correlated significantly with body mass index (BMI) (β = -0.0334, P = 0.0001) in F 0 or F 1, with γ-glutamyltranspeptidase levels (β = 0.0048, P = 0.0012) in F 2, and with fibrosis stage (β = 0.2921, P = 0.0044) and hyaluronic acid levels (β = 0.0012, P = 0.0025) in F 3 or F 4. The ARFI cutoff value was 1.28 m/s for F ≥ 2, 1.44 m/s for F ≥ 3, and 1.73 m/s for F 4., Conclusion: ARFI correlated with fibrosis stage and hyaluronic acid but not with inflammation. ARFI was affected by BMI, γ-glutamyltranspeptidase, and hyaluronic acid in each fibrosis stage.

Transient abnormal myelopoiesis (TAM) in neonates with Down syndrome (DS) is characterized by the transient appearance of blast cells, which resolves spontaneously. Approximately 20 % of patients with TAM die at an early age due to organ failure, including liver disease. We studied 25 DS-TAM patients retrospectively to clarify the correlation between clinical and laboratory characteristics and liver diseases. Early death (<6 months of age) occurred in four of the 25 patients (16.0 %), and two of those four patients died due to liver failure. Although physiologic jaundice improved gradually after a week, all DS patients had elevated D-Bil levels during the clinical course of TAM, except one who suffered early death. The median peak day of the WBC count, total bilirubin (T-Bil) and D-Bil levels was: day 1 (range day 0-57), day 8 (range day 1-55), and day 17 (range 1-53), respectively. Our results reveal that all patients with DS-TAM may develop liver disease irrespective of the absence or presence of symptoms and risk factors for early death. In patients of DS-TAM, careful observation of the level of D-Bil is needed by at least 1 month of age for the detection of liver disease risk.

Mutations in Wilms tumor 1 (WT1) have been reported in 10-22 % of patients with cytogenetically normal acute myeloid leukemia (CN-AML), but the prognostic implications of these abnormalities have not been clarified in either adults or children. One hundred and fifty-seven pediatric AML patients were analyzed for WT1 mutations around hotspots at exons 7 and 9; however, amplification of the WT1 gene by the reverse transcriptase-polymerase chain reaction was not completed in four cases (2.5 %). Of the 153 evaluable patients, 10 patients (6.5 %) had a mutation in WT1. The incidence of WT1 mutations was significantly higher in CN-AML than in others (15.2 vs. 4.5 %, respectively, P = 0.03). Of the 10 WT1-mutated cases, eight (80 %) had mutations in other genes, including FLT3-ITD in two cases, FLT3-D835 mutation in two, KIT mutation in three, MLL-PTD in three, NRAS mutation in one, and KRAS mutation in two (in some cases, more than one additional gene was mutated). The incidences of KIT and FLT3-D835 mutations were significantly higher in patients with than in those without WT1 mutation. No significant differences were observed in the 3-year overall survival and disease-free survival; however, the presence of WT1 mutation was related to a poor prognosis in patients with CN-AML, excluding those with FLT3-ITD and those younger than 3 years.

Langerhans cell histiocytosis (LCH) can be a single system or multi-system disease. Both disease types can be associated with multi-focal bone lesions, but their bone involvement patterns have not been compared systematically. Of the new pediatric LCH cases enrolled into the JLSG-02 study during 2002-2007, 67 cases of single system multifocal bone (SMFB) LCH and 97 cases of multi-system bone (MSB) LCH were analyzed to determine if the bone involvement patterns differ in these two types, and whether these differences correlate with outcome. Statistical analysis was performed with Mann-Whitney U test, Fisher's exact test, and other measures. Onset ages were higher for SMFB (P < 0.001), but the two types did not differ in the number of bone lesions per patient. The skull was most frequently affected in both types, followed by the spine. Lesions in the temporal bone (P = 0.002), ear-petrous bone (P < 0.001), orbita (P = 0.003), and zygomatic bone (P = 0.016) were significantly more common in MSB. The two types did not differ in response to treatment, but MSB was associated with a significantly higher incidence of diabetes insipidus (DI) (P < 0.001). Novel measures are required in preventing the development of DI in MSB-type LCH patients with "risk" bone lesions.