Poorer outcome of childhood acute lymphoblastic leukemia in the Bedouin population: A report from the Berlin-Frankfurt-Muenster-based Israeli national protocols.

BACKGROUND: Therapy outcomes for childhood acute lymphoblastic leukemia (ALL) had substantially improved in the last decades, but variability across racial and ethnic groups was identified in some clinical studies. In this study, we aimed to investigate whether such a difference in outcome is found in the diverse ethnicities in Israel as well. METHODS: A retrospective study was conducted among 1154 patients (855 Jews, 195 Muslims, 52 Bedouins, 26 Druze, and 26 others) aged 1 to 21 years, who were diagnosed with ALL between 1989 and 2011 and were treated according to the same Berlin-Frankfurt-Muenster-based Israel National Study protocols. RESULTS: Bedouins had a higher incidence of t(1;19) (16% vs 3% for non-Bedouins) and a lower incidence of high-hyperdiploidy (10% vs 25% for non-Bedouins) (P = 0.01). Five-year event-free survival (EFS) and overall survival (OS) were poorer for the Bedouins (60.3% ± 7.2% and 63.1% ± 7.2%, respectively) compared with the Jews, Muslims, and Druze (80.4% ± 1.4%, 77.3% ± 3.2%, and 84% ± 7.3%, respectively, for EFS [P = 0.02], and 86.3% ± 1.2%, 82.3% ± 2.9%, and 88.3% ± 6.4%, respectively, for OS [P = 0.002]). Adherence to intensive chemotherapy was similar between the Muslims and the Bedouins. CONCLUSIONS: Our findings suggest that the Bedouins, a highly inbred ethnic Arab people, may be considered a higher risk group that may need more intensive chemotherapy and/or supportive care in order to improve their outcome.

Growth and pubertal patterns in young survivors of childhood acute lymphoblastic leukemia.

BACKGROUND: Survivors of acute lymphoblastic leukemia (ALL) may experience endocrine dysfunction. This study evaluated growth and pubertal patterns in survivors of childhood ALL. METHODS: Longitudinal assessment of anthropometric measurements and pubertal status was performed in a retrospective cohort of survivors (n=183). Median age at last endocrine visit was 16.1 years (range 8.2-27.6); median follow-up time was 8.7 years (range 3-21.4). RESULTS: Treatment with chemotherapy+prophylactic cranial radiation (pCRT, n=29) was associated with lower mean height standard deviation score (SDS) than chemotherapy alone (n=154) (p=0.001) and higher prevalence of adult short stature (13% vs. 2.2%). Mean age at pubertal onset was normal (girls: 10.3±1.3 years; boys: 12.0±1.3 years). Precocious puberty, diagnosed in 8.7% of patients, was more prevalent in pCRT-treated girls. Rates of overweight and obesity were 22.9% and 9.3%, respectively. Predictors of endocrine disorders were pCRT (p=0.031) and female gender (p=0.041); of obesity, higher body mass index (BMI)-SDS at diagnosis (p=0.001); and of short stature, lower height-SDS at diagnosis (p=0.038). CONCLUSIONS: Most childhood ALL survivors given chemotherapy alone attain normal adult height and puberty. Childhood ALL survivors are at increased risk of overweight, especially those with increased BMI at diagnosis. Clinicians should screen for overweight early in survivorship and introduce early interventions.

miR expression profiling at diagnosis predicts relapse in pediatric precursor B-cell acute lymphoblastic leukemia.

Our aim was to identify miRNAs that can predict risk of relapse in pediatric patients with acute lymphoblastic leukemia (ALL). Following high-throughput miRNA expression analysis (48 samples), five miRs were selected for further confirmation performed by real time quantitative PCR on a cohort of precursor B-cell ALL patients (n = 138). The results were correlated with clinical parameters and outcome. Low expression of miR-151-5p, and miR-451, and high expression of miR-1290 or a combination of all three predicted inferior relapse free survival (P = 0.007, 0.042, 0.025, and <0.0001, respectively). Cox regression analysis identified aberrant expression of the three miRs as an independent prognostic marker with a 10.5-fold increased risk of relapse (P = 0.041) in PCR-MRD non-high risk patients. Furthermore, following exclusion of patients harboring IKZF1 deletion, the aberrant expression of all three miRs could identify patients with a 24.5-fold increased risk to relapse (P < 0.0001). The prognostic relevance of the three miRNAs was evaluated in a non-BFM treated precursor B-cell ALL cohort (n = 33). A significant correlation between an aberrant expression of at least one of the three miRs and poor outcome was maintained (P < 0.0001). Our results identify an expression profile of miR-151-5p, miR-451, and miR-1290 as a novel biomarker for outcome in pediatric precursor B-cell ALL patients, regardless of treatment protocol. The use of these markers may lead to improved risk stratification at diagnosis and allow early therapeutic interventions in an attempt to improve survival of high risk patients.

The prognostic significance of early treatment response in pediatric relapsed acute myeloid leukemia: results of the international study Relapsed AML 2001/01.

The prognostic significance of early response to treatment has not been reported in relapsed pediatric acute myeloid leukemia. In order to identify an early and easily applicable prognostic factor allowing subsequent treatment modifications, we assessed leukemic blast counts in the bone marrow by morphology on days 15 and 28 after first reinduction in 338 patients of the international Relapsed-AML2001/01 trial. Both day 15 and day 28 status was classified as good (≤20% leukemic blasts) in 77% of patients. The correlation between day 15 and 28 blast percentages was significant, but not strong (Spearman correlation coefficient = 0.49, P<0.001). Survival probability decreased in a stepwise fashion along with rising blast counts at day 28. Patients with bone marrow blast counts at this time-point of ≤5%, 6-10%, 11-20% and >20% had 4-year probabilities of survival of 52%±3% versus 36%±10% versus 21%±9% versus 14%±4%, respectively, P<0.0001; this trend was not seen for day 15 results. Multivariate analysis showed that early treatment response at day 28 had the strongest prognostic significance, superseding even time to relapse (< or ≥12 months). In conclusion, an early response to treatment, measured on day 28, is a strong and independent prognostic factor potentially useful for treatment stratification in pediatric relapsed acute myeloid leukemia. This study was registered with ISRCTN code: 94206677.

Acute lymphoblastic leukemia in children with Down syndrome: a retrospective analysis from the Ponte di Legno study group.

Children with Down syndrome (DS) have an increased risk of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL). The prognostic factors and outcome of DS-ALL patients treated in contemporary protocols are uncertain. We studied 653 DS-ALL patients enrolled in 16 international trials from 1995 to 2004. Non-DS BCP-ALL patients from the Dutch Child Oncology Group and Berlin-Frankfurt-Münster were reference cohorts. DS-ALL patients had a higher 8-year cumulative incidence of relapse (26% ± 2% vs 15% ± 1%, P < .001) and 2-year treatment-related mortality (TRM) (7% ± 1% vs 2.0% ± <1%, P < .0001) than non-DS patients, resulting in lower 8-year event-free survival (EFS) (64% ± 2% vs 81% ± 2%, P < .0001) and overall survival (74% ± 2% vs 89% ± 1%, P < .0001). Independent favorable prognostic factors include age <6 years (hazard ratio [HR] = 0.58, P = .002), white blood cell (WBC) count <10 × 10(9)/L (HR = 0.60, P = .005), and ETV6-RUNX1 (HR = 0.14, P = .006) for EFS and age (HR = 0.48, P < .001), ETV6-RUNX1 (HR = 0.1, P = .016) and high hyperdiploidy (HeH) (HR = 0.29, P = .04) for relapse-free survival. TRM was the major cause of death in ETV6-RUNX1 and HeH DS-ALLs. Thus, while relapse is the main contributor to poorer survival in DS-ALL, infection-associated TRM was increased in all protocol elements, unrelated to treatment phase or regimen. Future strategies to improve outcome in DS-ALL should include improved supportive care throughout therapy and reduction of therapy in newly identified good-prognosis subgroups.

Intensive chemotherapy for childhood acute lymphoblastic leukemia: results of the randomized intercontinental trial ALL IC-BFM 2002.

PURPOSE: From 2002 to 2007, the International Berlin-Frankfurt-Münster Study Group conducted a prospective randomized clinical trial (ALL IC-BFM 2002) for the management of childhood acute lymphoblastic leukemia (ALL) in 15 countries on three continents. The aim of this trial was to explore the impact of differential delayed intensification (DI) on outcome in all risk groups. PATIENTS AND METHODS: For this trial, 5,060 eligible patients were divided into three risk groups according to age, WBC, early treatment response, and unfavorable genetic aberrations. DI was randomized as follows: standard risk (SR), two 4-week intensive elements (protocol III) versus one 7-week protocol II; intermediate risk (IR), protocol III × 3 versus protocol II × 1; high risk (HR), protocol III × 3 versus either protocol II × 2 (Associazione Italiana Ematologia Oncologia Pediatrica [AIEOP] option), or 3 HR blocks plus single protocol II (Berlin-Frankfurt-Münster [BFM] option). RESULTS: At 5 years, the probabilities of event-free survival and survival were 74% (± 1%) and 82% (± 1%) for all 5,060 eligible patients, 81% and 90% for the SR (n = 1,564), 75% and 83% for the IR (n = 2,650), and 55% and 62% for the HR (n = 846) groups, respectively. No improvement was accomplished by more intense and/or prolonged DI. CONCLUSION: The ALL IC-BFM 2002 trial is a good example of international collaboration in pediatric oncology. A wide platform of countries able to run randomized studies in ALL has been established. Although the alternative DI did not improve outcome compared with standard treatment and the overall results are worse than those achieved by longer established leukemia groups, the national results have generally improved.

Normal karyotype is a poor prognostic factor in myeloid leukemia of Down syndrome: a retrospective, international study.

Myeloid leukemia of Down syndrome has a better prognosis than sporadic pediatric acute myeloid leukemia. Most cases of myeloid leukemia of Down syndrome are characterized by additional cytogenetic changes besides the constitutional trisomy 21, but their potential prognostic impact is not known. We, therefore, conducted an international retrospective study of clinical characteristics, cytogenetics, treatment, and outcome of 451 children with myeloid leukemia of Down syndrome. All karyotypes were centrally reviewed before assigning patients to subgroups. The overall 7-year event-free survival for the entire cohort was 78% (± 2%), with the overall survival rate being 79% (± 2%), the cumulative incidence of relapse 12% (± 2%), and the cumulative incidence of toxic death 7% (± 1%). Outcome estimates showed large differences across the different cytogenetic subgroups. Based on the cumulative incidence of relapse, we could risk-stratify patients into two groups: cases with a normal karyotype (n=103) with a higher cumulative incidence of relapse (21%± 4%) than cases with an aberrant karyotype (n=255) with a cumulative incidence of relapse of 9% (± 2%) (P=0.004). Multivariate analyses revealed that white blood cell count ≥ 20 × 10(9)/L and age >3 years were independent predictors for poor event-free survival, while normal karyotype independently predicted inferior overall survival, event-free survival, and relapse-free survival. In conclusion, this study showed large differences in outcome within patients with myeloid leukemia of Down syndrome and identified novel prognostic groups that predicted clinical outcome and hence may be used for stratification in future treatment protocols.

Second malignant neoplasms after treatment of childhood acute lymphoblastic leukemia.

PURPOSE: Second malignant neoplasms (SMNs) after diagnosis of childhood acute lymphoblastic leukemia (ALL) are rare events. PATIENTS AND METHODS: We analyzed data on risk factors and outcomes of 642 children with SMNs occurring after treatment for ALL from 18 collaborative study groups between 1980 and 2007. RESULTS: Acute myeloid leukemia (AML; n = 186), myelodysplastic syndrome (MDS; n = 69), and nonmeningioma brain tumor (n = 116) were the most common types of SMNs and had the poorest outcome (5-year survival rate, 18.1% ± 2.9%, 31.1% ± 6.2%, and 18.3% ± 3.8%, respectively). Five-year survival estimates for AML were 11.2% ± 2.9% for 125 patients diagnosed before 2000 and 34.1% ± 6.3% for 61 patients diagnosed after 2000 (P < .001); 5-year survival estimates for MDS were 17.1% ± 6.4% (n = 36) and 48.2% ± 10.6% (n = 33; P = .005). Allogeneic stem-cell transplantation failed to improve outcome of secondary myeloid malignancies after adjusting for waiting time to transplantation. Five-year survival rates were above 90% for patients with meningioma, Hodgkin lymphoma, thyroid carcinoma, basal cell carcinoma, and parotid gland tumor, and 68.5% ± 6.4% for those with non-Hodgkin lymphoma. Eighty-nine percent of patients with brain tumors had received cranial irradiation. Solid tumors were associated with cyclophosphamide exposure, and myeloid malignancy was associated with topoisomerase II inhibitors and starting doses of methotrexate of at least 25 mg/m(2) per week and mercaptopurine of at least 75 mg/m(2) per day. Myeloid malignancies with monosomy 7/5q- were associated with high hyperdiploid ALL karyotypes, whereas 11q23/MLL-rearranged AML or MDS was associated with ALL harboring translocations of t(9;22), t(4;11), t(1;19), and t(12;21) (P = .03). CONCLUSION: SMNs, except for brain tumors, AML, and MDS, have outcomes similar to their primary counterparts.

Improved outcome in pediatric relapsed acute myeloid leukemia: results of a randomized trial on liposomal daunorubicin by the International BFM Study Group.

PURPOSE: In pediatric relapsed acute myeloid leukemia (AML), optimal reinduction therapy is unknown. Studies suggest that liposomal daunorubicin (DNX; DaunoXome; Galen, Craigavon, United Kingdom) is effective and less cardiotoxic, which is important in this setting. These considerations led to a randomized phase III study by the International Berlin-Frankfurt-Münster Study Group. PATIENTS AND METHODS: Patients with relapsed or primary refractory non-French-American-British type M3 AML who were younger than 21 years of age were eligible. Patients were randomly assigned to fludarabine, cytarabine, and granulocyte colony-stimulating factor (FLAG) or to FLAG plus DNX in the first reinduction course. The primary end point was status of the bone marrow (BM) sampled shortly before the second course of chemotherapy (the day 28 BM). Data are presented according to intention-to-treat for all 394 randomly assigned patients (median follow-up, 4.0 years). RESULTS: The complete remission (CR) rate was 64%, and the 4-year probability of survival (pOS) was 38% (SE, 3%). The day 28 BM status (available in 359 patients) was good (≤ 20% leukemic blasts) in 80% of patients randomly assigned to FLAG/DNX and 70% for patients randomly assigned to FLAG (P = .04). Concerning secondary end points, the CR rate was 69% with FLAG/DNX and 59% with FLAG (P = .07), but overall survival was similar. However, core-binding factor (CBF) AML treated with FLAG/DNX resulted in pOS of 82% versus 58% with FLAG (P = .04). Grade 3 to 4 toxicity was essentially similar in both groups. CONCLUSION: DNX added to FLAG improves early treatment response in pediatric relapsed AML. Overall long-term survival was similar, but CBF-AML showed an improved survival with FLAG/DNX. International collaboration proved feasible and resulted in the best outcome for pediatric relapsed AML reported thus far.

Prospective comparison of two flow cytometry methodologies for monitoring minimal residual disease in a multicenter treatment protocol of childhood acute lymphoblastic leukemia.

BACKGROUND: Minimal residual disease (MRD) is a powerful prognostic indicator in childhood acute lymphoblastic leukemia (ALL). Multiparametric flow cytometry (FC) is a rapid and sensitive methodology for detection of MRD, applicable for most patients and is being incorporated in multicenter treatment protocols. The influence of different techniques and of individual interpretation of data on the interlaboratory variability in FC-MRD determinations has not been described. METHODS: We compared FC-MRD of identical bone marrow samples processed as either Ficoll separated mononuclear cells or lyse and wash nucleated cells (NC) in two central laboratories of a national multicenter childhood ALL study. A total of 290 samples at diagnosis and 494 follow-up samples (Day-15 n = 261; Day-33 n = 233) were analyzed. A group of 52 paired list mode data (LMD) of D-15 and D-33 samples was blindly reanalyzed by both laboratories. RESULTS: Pearson correlations for all samples of D-15 (n = 261) and D-33 (n = 233) were 0.875 and 0.82, respectively (P < 0.001), being lower for T-ALL 0.716 and 0.719, respectively. Quantitative concordance defined as less than 0.5 log difference in MRD measured by the two methodologies was 80.8% at D-15 but only in 57.9% at D-33. Reanalysis of LMD revealed that data interpretation explained half of the discordance. CONCLUSIONS: FC-MRD analysis of childhood ALL is a robust method during the earliest phases of induction therapy in a multicentric setting. Standardization of data analysis could improve about half of the discordance between different technical approaches.

Neuropsychiatric manifestations in Langerhans' cell histiocytosis disease: a case report and review of the literature.

The spectrum of the possible manifestations of Langerhans' cell histiocytosis in children is very wide, ranging from a simple rash to major multiorgan disease. There may be hypothalamic and pituitary dysfunction or more global neurological and neuropsychiatric manifestations when the central nervous system is affected. The cerebellum is preferentially affected for yet undetermined reasons. The clinical presentation includes motor dysfunction as well as cognitive, behavioral, and psychiatric expression of the ongoing neurodegeneration. We report a young patient with Langerhans' cell histiocytosis who underwent an unusual course of psychiatric deterioration.

2p24 Gain region harboring MYCN gene compared with MYCN amplified and nonamplified neuroblastoma: biological and clinical characteristics.

Although the role of MYCN amplification in neuroblastoma is well established, the biological and clinical characteristics of the 2p gain region harboring the MYCN gene remain unclear. The aim of this study was to compare the biological and clinical characteristics of these tumors with MYCN amplified and nonamplified neuroblastoma and to determine their impact on disease outcome. Samples from 177 patients were analyzed by fluorescence in situ hybridization, including MYCN, 1p, 17q, and 11q regions; 2p gain was identified in 25 patients, MYCN amplification in 31, and no amplification in 121 patients. Patients with 2p gain had a significantly worse 5-year event-free survival rate than patients with no MYCN amplified (P < 0.001), and an intermediate 5-year overall survival rate difference existed between the MYCN amplified tumors (P = 0.025) and nonamplified (P = 0.003) groups. All of the 2p gain samples were associated with segmental and/or numerical alterations in the other tested regions. The presence of segmental alterations with or without MYCN amplification was recently found to be the strongest predictor of relapse in a multivariate analysis. The results of the present study suggest that the determination of MYCN gene copy number relative to chromosome 2, when evaluating MYCN status at diagnosis, may help to reveal the underlying genetic pattern of these tumors and better understand their clinical behavior.

Detection of residual B precursor lymphoblastic leukemia by uniform gating flow cytometry.

BACKGROUND: Residual disease (RD) is an important prognostic factor in acute lymphoblastic leukemia (ALL). Flow cytometry (FC)-based RD detection is easy to perform, but interpretation requires expert analysis due to individual differences among patients. PROCEDURE: We focused at the design of standardized and reproducible RD monitoring in ALL. RD was investigated by a uniform gating strategy, which was designed internationally and tested in one center by Ig/TCR rearrangements. RESULTS: For each gate, positivity cutoff value was assigned using quantification of non-leukemic background. Comparing to Ig/TCR at 0.1% level, 80 of 103 specimens were correctly diagnosed by FC. The predictive value of FC RD at day 15 was then analyzed. In B lineage ALL, day 15 FC significantly correlated with Ig/TCR results at day 33 and/or week 12 (P < 0.01). No significant correlation was found in T lineage ALL. CONCLUSIONS: Thus, FC with preset uniform gating at day 15 predicts PCR-detectable MRD in B precursor ALL. Presented data may be used to define new polychromatic cytometric diagnostics of MRD including semiautomatic assessment. Pediatr Blood Cancer 2010; 54:62-70. (c) 2009 Wiley-Liss, Inc.

Salvage treatment for children with refractory first or second relapse of acute myeloid leukaemia with gemtuzumab ozogamicin: results of a phase II study.

The prognosis of children with relapsed/refractory acute myeloid leukaemia (AML) is poor, and new therapies are needed. Gemtuzumab ozogamicin (GO) is an anti-CD33 antibody linked to the antitumor antibiotic calicheamicin. We conducted an investigator-initiated phase II study with GO to assess its efficacy and safety, administering two dosages of 7.5 mg/m(2) with a 14 d-interval. Thirty children who were refractory to re-induction at first relapse or suffered from second relapse of AML received a total of 64 infusions of GO. The response rate [complete remission (CR) and CR with insufficient platelet recovery] was 37%. Nine patients were subsequently transplanted (median time to transplant, 4 weeks, range 3-21 weeks), and three of these patients are currently in continuous CR with a median follow-up of >3 years, and can considered to be cured. This resulted in a statistically significant survival advantage for children who responded to GO versus those who did not [27% (standard error 13%) vs. 0%, respectively, P = 0.001]. All other children died, mainly from progressive disease. The treatment was generally well tolerated by most patients. The frequency of transient transaminatis was low. All but one patient received defibrotide prophylaxis during the transplant procedure, and no cases of veno-occlusive disease were noted. This study showed a favourable safety/efficacy profile of single-agent GO in children with refractory first or second relapse of AML.

Extended triple intrathecal therapy in children with T-cell acute lymphoblastic leukaemia: a report from the Israeli National ALL-Studies.

Owing to the increased central nervous system (CNS) relapse risk in T-cell acute lymphoblastic leukaemia (ALL), it is unclear whether preventive cranial radiation (pCRT) can be safely omitted. In this study, pCRT was replaced by extended triple intrathecal therapy (TIT) in prednisone good early responders - medium-risk (MR) group, accounting for 76% of T-ALL patients. From 1989 to 2003, 143 T-ALL patients aged 1-18 years were enrolled in the Israel National Studies (INS) 89 (n = 84) and INS 98 (n = 59) trials, based on ALL-Berlin-Frankfurt-Munster (BFM) 86/90 and ALL-BFM 95 protocols, respectively. Five-year event-free survival (EFS) of the MR group in the INS 89 (n = 60) was 70 +/- 5.9% and the INS 98 (n = 43), 83.7 +/- 5.6% (P = 0.12); the cumulative incidence (CI) of any CNS relapse was 5.0 +/- 2.8% and 2.3 +/- 2.3% (P = 0.50), respectively. There was no difference in outcome between MR patients with a white blood cell count (WBC) >or=100 x 10(9)/l treated with extended TIT (n = 17) or pCRT (n = 10). For all T-ALL patients, 5-year EFS was 61.9 +/- 5.3% in INS 89 and 72.9 +/- 5.8% in INS 98, (P = 0.21); the CI of any CNS relapse was 7.1 +/- 2.8% and 1.7 +/- 1.7% (P = 0.142), respectively. Outcome of T-ALL MR patients given extended TIT in the context of BFM-based protocols with long-term follow-up appeared to be comparable to studies in which a larger proportion of patients was irradiated, and was associated with low risk of CNS relapse, regardless of the WBC.

Bone marrow minimal disseminated disease (MDD) and minimal residual disease (MRD) in childhood T-cell lymphoblastic lymphoma stage III, detected by flow cytometry (FC) and real-time quantitative polymerase chain reaction (RQ-PCR).

BACKGROUND: Despite overlapping features of T-cell lymphoblastic lymphoma (T-LLy) and T-cell acute lymphoblastic leukemia (T-ALL), which respond favorably to T-ALL treatment, clinical and biological differences exist. We retrospectively assessed the prevalence of submicroscopic bone marrow (BM) minimal disseminated disease (MDD) at diagnosis and the early response to treatment (minimal residual disease--MRD) and their prognostic significance in 17 children with stage III T-LLy treated according to Berlin-Frankfurt-Munster (BFM) non-Hodgkin lymphoma protocols. PROCEDURE: Four-color flow cytometry (FC) was used for lymphoma associated immunophenotype and real-time quantitative polymerase chain reaction (RQ-PCR) for T-cell receptor (TCR beta/delta/gamma) gene rearrangements with at least 0.01% sensitivity. RESULTS: Two markers per patient were identified in all cases using FC and in 80% using RQ-PCR. BM MDD at diagnosis of >or=0.01% was detected by FC and RQ-PCR in 88% and 80% of patients, respectively, and by at least one of the methods in all patients. A significant correlation was achieved between the methods by Pearson correlation analysis (P = 0.004). MRD levels significantly decreased to very low levels on day 33 in 9 out of 10 patients studied. The only patient that remained positive relapsed. CONCLUSIONS: MDD was prevalent in stage III T-LLy, for which we could not prove a prognostic significance in the context of ALL-like treatment. This study shows that both FC and RQ-PCR methods are efficient for MDD and MRD analyses in T-LLy.

Mutations of JAK2 in acute lymphoblastic leukaemias associated with Down's syndrome.

BACKGROUND: Children with Down's syndrome have a greatly increased risk of acute megakaryoblastic and acute lymphoblastic leukaemias. Acute megakaryoblastic leukaemia in Down's syndrome is characterised by a somatic mutation in GATA1. Constitutive activation of the JAK/STAT (Janus kinase and signal transducer and activator of transcription) pathway occurs in several haematopoietic malignant diseases. We tested the hypothesis that mutations in JAK2 might be a common molecular event in acute lymphoblastic leukaemia associated with Down's syndrome. METHODS: JAK2 DNA mutational analysis was done on diagnostic bone marrow samples obtained from 88 patients with Down's syndrome-associated acute lymphoblastic leukaemia; and 216 patients with sporadic acute lymphoblastic leukaemia, Down's syndrome-associated acute megakaryoblastic leukaemia, and essential thrombocythaemia. Functional consequences of identified mutations were studied in mouse haematopoietic progenitor cells. FINDINGS: Somatically acquired JAK2 mutations were identified in 16 (18%) patients with Down's syndrome-associated acute lymphoblastic leukaemia. The only patient with non-Down's syndrome-associated leukaemia but with a JAK2 mutation had an isochromosome 21q. Children with a JAK2 mutation were younger (mean [SE] age 4.5 years [0.86] vs 8.6 years [0.59], p<0.0001) at diagnosis. Five mutant alleles were identified, each affecting a highly conserved arginine residue (R683). These mutations immortalised primary mouse haematopoietic progenitor cells in vitro, and caused constitutive Jak/Stat activation and cytokine-independent growth of BaF3 cells, which was sensitive to pharmacological inhibition with JAK inhibitor I. In modelling studies of the JAK2 pseudokinase domain, R683 was situated in an exposed conserved region separated from the one implicated in myeloproliferative disorders. INTERPRETATION: A specific genotype-phenotype association exists between the type of somatic mutation within the JAK2 pseudokinase domain and the development of B-lymphoid or myeloid neoplasms. Somatically acquired R683 JAK2 mutations define a distinct acute lymphoblastic leukaemia subgroup that is uniquely associated with trisomy 21. JAK2 inhibitors could be useful for treatment of this leukaemia. FUNDING: Israel Trade Ministry, Israel Science Ministry, Jewish National Fund UK, Sam Waxman Cancer Research Foundation, Israel Science Foundation, Israel Cancer Association, Curtis Katz, Constantiner Institute for Molecular Genetics, German-Israel Foundation, and European Commission FP6 Integrated Project EUROHEAR.

Cytogenetic features of acute lymphoblastic and myeloid leukemias in pediatric patients with Down syndrome: an iBFM-SG study.

Children with Down syndrome (DS) have a markedly increased risk of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). To identify chromosomal changes cooperating with +21 that may provide information on the pathogenesis of these leukemias, we analyzed 215 DS-ALLs and 189 DS-AMLs. Unlike previous smaller series, a significant proportion of DS-ALLs had the typical B-cell precursor ALL abnormalities high hyperdiploidy (HeH; 11%) and t(12;21)(p13;q22) (10%). The HeH DS-ALLs were characterized by gains of the same chromosomes as non-DS-HeH, suggesting the same etiology/pathogenesis. In addition, specific genetic subtypes of DS-ALL were suggested by the significant overrepresentation of cases with +X, t(8;14)(q11;q32), and del(9p). Unlike DS-ALL, the common translocations associated with non-DS-AML were rare in DS-AML, which instead were characterized by the frequent presence of dup(1q), del(6q), del(7p), dup(7q), +8, +11, del(16q), and +21. This series of DS leukemias-the largest to date-reveals that DS-ALL is a heterogeneous disorder that comprises both t(12;21) and HeH as well as DS-related abnormalities. Furthermore, this analysis confirms that DS-AML is a distinct entity, originating through other genetic pathways than do non-DS-AMLs, and suggests that unbalanced changes such as dup(1q), +8, and +21 are involved in the leukemogenic process.

Short telomeres: a novel potential predictor of relapse in Ewing sarcoma.

PURPOSE: Despite advances in therapy, >50% of patients with Ewing sarcoma will relapse. The current prognostic factors are not optimal for risk prediction. Studies have shown that telomere length could predict outcome in different malignancies. Our aim was to evaluate whether telomere length could be a better prognostic factor in Ewing sarcoma and correlate the results with clinical variables, outcome, and chromosomal instability. EXPERIMENTAL DESIGN: Telomere length was determined in the primary tumor and peripheral blood of 32 patients with Ewing sarcoma. Chromosomal instability was evaluated by combining classical cytogenetics, comparative genomic hybridization and random aneuploidy. Telomere length was correlated to clinical variables, chromosomal instability, and outcome. RESULTS: In 75% of the tumors, changes in telomere length, when compared with the corresponding peripheral blood lymphocytes, were noted. The majority of changes consisted of a reduction in telomere length. Patients harboring shorter telomeres had a significantly adverse outcome (P = 0.015). Chromosomal instability was identified in 65% of tumors, significantly correlating with short telomeres (P = 0.0094). Using multivariate analysis, telomere length remained the only significant prognostic variable (P = 0.034). Patients with short telomeres had a 5.3-fold risk of relapse as compared to those with unchanged or longer telomeres. CONCLUSION: We have shown that tumors with telomere length reduction result in genomic instability. In addition, telomere length reduction was the only significant predictor of outcome. We suggest that reduction of telomere length in tumor cells at diagnosis could serve as a prognostic marker in Ewing sarcoma.

Monosomy 7 and deletion 7q in children and adolescents with acute myeloid leukemia: an international retrospective study.

Monosomy 7 (-7) and deletion 7q \del(7q)] are rare in childhood acute myeloid leukemia (AML). We retrospectively collected data on 258 children with AML or refractory anemia with excess blasts in transformation (RAEB-T) and -7 or del(7q) with or without other cytogenetic aberrations \+/- other]. Karyotypes included -7 (n = 90), -7 other (n = 82), del(7q) (n = 21), and del(7q) other (n = 65). Complete remission (CR) was achieved in fewer patients with -7 +/- other compared with del(7q) +/- other (61% versus 89%, P < .001). Overall, the 5-year survival rate was 39% (SE, 3%). Survival was superior in del(7q) +/- other compared with -7 +/- other (51% versus 30%, P < .01). Cytogenetic aberrations considered favorable in AML \t(8;21)(q22;q22), inv(16)(p13q22), t(15;17)(q22;q21), t(9;11)(p22;q23)] (n = 24) were strongly associated with del(7q) and a higher 5-year survival rate compared with del(7q) without favorable cytogenetics (75% versus 46%, P = .03). Patients with -7 and inv(3),-5/del(5q), or + 21 had a 5-year survival rate of 5%. Stem cell transplantation analyzed as a time-dependent variable had no impact on overall survival. However, patients not achieving CR had a 31% survival rate after stem cell transplantation. Childhood AML with chromosome 7 aberrations represents a heterogeneous group of disorders with additional cytogenetic aberrations having a major prognostic impact which should be reflected in future risk-group stratification.