ETV6/RUNX1 abrogates mitotic checkpoint function and targets its key player MAD2L1.

Approximately 25% of childhood B-cell precursor acute lymphoblastic leukemia have an ETV6/RUNX1 (E/R) gene fusion that results from a t(12;21). This genetic subgroup of leukemia is associated with near-triploidy, near-tetraploidy, and trisomy 21 as rather specific types of secondary changes. Here, we show that, unlike various controls, E/R-expressing Ba/F3 clones acquire a tetraploid karyotype on prolonged culture, corroborating the assumption that E/R may attenuate the mitotic checkpoint (MC).

Prognostic significance of minimal residual disease in infants with acute lymphoblastic leukemia treated within the Interfant-99 protocol.

Acute lymphoblastic leukemia (ALL) in infants younger than 1 year is a rare but relatively homogeneous disease ( approximately 80% MLL gene rearranged, approximately 70% CD10-negative) when compared with childhood and adult ALL. Several studies in children and adults with ALL have shown that minimal residual disease (MRD) status is a strong and independent prognostic factor. We therefore evaluated the prognostic significance of MRD in infant ALL.

Chromosome 14 copy number-dependent IGH gene rearrangement patterns in high hyperdiploid childhood B-cell precursor ALL: implications for leukemia biology and minimal residual disease analysis.

Childhood B-cell precursor acute lymphoblastic leukemia (BCP ALL) is generally a clonal disease in which the number of IGH rearrangements per cell does not exceed the number of the IGH alleles on chromosome 14. Consequently, monoclonal high hyperdiploid (HeH) cases with a trisomy 14 can harbor three rearrangements, a pattern that otherwise may be misinterpreted to be oligoclonal. Oligoclonal IGH rearrangements, on the other hand, may be instable at relapse and should therefore not be used for minimal residual disease analysis.

Cluster analysis of genomic ETV6-RUNX1 (TEL-AML1) fusion sites in childhood acute lymphoblastic leukemia.

Fusion between ETV6 and RUNX1 defines the largest genetic subgroup in childhood ALL. The genomic fusion site, unique to individual patients and specific for the malignant clone, represents an ideal molecular marker for quantification of minimal residual disease. Sequencing of DNA breakpoints has been difficult due to the extended size of the respective breakpoint cluster regions.

Role of the erythropoietin receptor in ETV6/RUNX1-positive acute lymphoblastic leukemia.

Purpose: We explored the mechanisms leading to the distinct overexpression of EPOR as well as the effects of EPO signaling on ETV6/RUNX1-positive acute lymphoblastic leukemias.

Experimental Design: ETV6/RUNX1-expressing model cell lines and leukemic cells were used for real-time PCR of EPOR expression. Proliferation, viability, and apoptosis were analyzed on cells exposed to EPO, prednisone, or inhibitors of EPOR pathways by [3H]thymidine incorporation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Annexin V/propidium iodide staining.

Glucocorticoids in the treatment of children with acute lymphoblastic leukemia and hodgkin's disease: a pilot study on the adverse psychological reactions and possible associations with neurobiological, endocrine, and genetic markers.

Purpose: We did a controlled study to assess adverse psychological reactions (APR) associated with high-dose glucocorticoid therapy and tried to detect somatic correlates for the observed reactions.

Patients And Methods: Our study included 37 patients with acute lymphoblastic leukemia (ALL) and 11 patients with Morbus Hodgkin (MH) disease, who were treated with high-dose glucocorticoid therapy, and 26 control patients with other types of malignancies. APRs were assessed with a standardized measure via parent-report.

Screening for leukemia- and clone-specific markers at birth in children with T-cell precursor ALL suggests a predominantly postnatal origin.

Childhood T-cell precursor acute lymphoblastic leukemia (TCP ALL) is an aggressive disease with a presumably short latency that differs in many biologic respects from B-cell precursor (BCP) ALL. We therefore addressed the issue of in utero origin of this particular type of leukemia by tracing oncogenic mutations and clone-specific molecular markers back to birth. These markers included various first- and second-hit genetic alterations (TCRD-LMO2 breakpoint regions, n = 2; TAL1 deletions, n = 3; Notch1 mutations, n = 1) and nononcogenic T-cell receptor rearrangements (n = 13) that were derived from leukemias of 16 children who were 1.

Optimization of PCR-based minimal residual disease diagnostics for childhood acute lymphoblastic leukemia in a multi-center setting.

Minimal residual disease (MRD) diagnostics is used for treatment stratification in childhood acute lymphoblastic leukemia. We aimed to identify and solve potential problems in multicenter MRD studies to achieve and maintain consistent results between the AIEOP/BFM ALL-2000 MRD laboratories. As the dot-blot hybridization method was replaced by the real-time quantitative polymerase chain reaction (RQ-PCR) method during the treatment protocol, special attention was given to the comparison of MRD data obtained by both methods and to the reproducibility of RQ-PCR data.

Acute lymphoblastic leukemia with t(4;11) in children 1 year and older: The 'big sister' of the infant disease?

The t(4;11)-positive acute lymphoblastic leukemia (ALL) is a rare disease in children above the age of 1 year. We studied the clinical and biological characteristics in 32 consecutively diagnosed childhood cases (median age 10.0 years, range 1.

Analysis of minimal residual disease by Ig/TCR gene rearrangements: guidelines for interpretation of real-time quantitative PCR data.

Most modern treatment protocols for acute lymphoblastic leukaemia (ALL) include the analysis of minimal residual disease (MRD). To ensure comparable MRD results between different MRD-polymerase chain reaction (PCR) laboratories, standardization and quality control are essential. The European Study Group on MRD detection in ALL (ESG-MRD-ALL), consisting of 30 MRD-PCR laboratories worldwide, has developed guidelines for the interpretation of real-time quantitative PCR-based MRD data.

RNAi-mediated silencing of TEL/AML1 reveals a heat-shock protein- and survivin-dependent mechanism for survival.

The TEL/AML1 fusion gene results from the most frequent t(12;21)(p13;q22) translocation in childhood acute lymphoblastic leukemia (ALL). Its contribution to transformation is largely unknown, in particular with respect to survival and apoptosis. We therefore silenced TEL/AML1 expression in leukemic REH cells by RNA inhibition, which eventually led to programmed cell death.

Leukemia-associated antigenic isoforms induce a specific immune response in children with T-ALL.

The potential immunogenicity of acute lymphoblastic leukemia of the T cell (T-ALL), a small subgroup of childhood leukemia with increased risk for treatment failure and early relapse, was addressed by serological identification of leukemia-derived antigens by recombinant expression cloning (SEREX). Thirteen antigens with homology to known genes that are involved in critical cellular processes were detected. Further characterization of the 4 novel isoforms revealed that 3 (HECTD1Delta, CX-ORF-15Delta and hCAP-EDelta) had restricted mRNA expression in more than 70% of T-ALLs (n = 22) and that specific antibodies against these isoforms were detected in up to 30% of patients (n = 16), with the highest frequency for HECTD1Delta.

Minimal residual disease analysis in children with t(12;21)-positive acute lymphoblastic leukemia: comparison of Ig/TCR rearrangements and the genomic fusion gene.

Quantification of minimal residual disease (MRD) based on clonotypic immunoglobulin/ T-cell receptor (Ig/TCR) gene rearrangements is widely used as an independent prognostic parameter in childhood acute lymphoblastic leukemia (ALL). In this study we compared MRD by quantification of Ig/TCR targets and genomic ETV6-RUNX1 specific sequences. In ten of twelve patients with t(12;21)+ ALL we observed concordance with rapid blast reduction in nine, and high-level persistence in one case.

Immunogenotype changes prevail in relapses of young children with TEL-AML1-positive acute lymphoblastic leukemia and derive mainly from clonal selection.

Purpose: Variations of the immunogenotype and TEL deletions in children with TEL-AML1+ acute lymphoblastic leukemia support the hypothesis that relapses derive from a persistent TEL-AML1+ preleukemic/leukemic clone rather than a resistant leukemia. We aimed at elucidating the relationship between the immunogenotype patterns at diagnosis and relapse as well as their clinical and biological relevance.

Patients And Methods: Immunoglobulin and T-cell receptor gene rearrangements were analyzed in 41 children with a TEL-AML1+ acute lymphoblastic leukemia and an early (up to 30 months after diagnosis; n = 12) or late (at 30 months or later; n = 29) disease recurrence by a standardized PCR approach.

Clonal variation of the immunogenotype in relapsed ETV6/RUNX1-positive acute lymphoblastic leukemia indicates subclone formation during early stages of leukemia development.

Recent data suggest that late relapses evolve from an ancestral ETV6/RUNX1-positive (also designated TEL/AML1-positive) clone resulting from secondary changes (ETV6 deletion) that differ from those of the initial leukemia and, as a consequence, may also deviate in their clonotypic immunoglobulin/T-cell receptor (IG/TCR) gene rearrangements. The aim of our study was to compare the immunogenotype and fluorescence in situ hybridization (FISH) patterns of the unrearranged ETV6 allele of matched diagnosis/relapse samples from 12 children with an early or late relapse. We identified varying degrees of differences in the IG/TCR in six of them.

High incidence and unique features of antigen receptor gene rearrangements in TEL-AML1-positive leukemias.

The t(12;21) translocation resulting in the TEL-AML1 gene fusion is found in 25% of childhood B-cell precursor (BCP) acute lymphoblastic leukemias (ALL). Since TEL-AML1 has been reported to induce cell cycle retardation and thus may influence somatic recombination, we analyzed 214 TEL-AML1-positive ALL by PCR for rearrangements of the immunoglobulin (Ig) and T-cell receptor (TCR) genes. As a control group, 174 childhood BCP ALL without a TEL-AML1 were used.

Flow cytometric detection of minimal residual disease in acute lymphoblastic leukemia.

Assessment of minimal residual disease (MRD) during the first months of therapy gives information on the timely response to treatment, and proves to be a powerful and independent indicator of treatment outcome in patients with acute lymphoblastic leukemia (ALL). Immunological evaluation by flow cytometry (FCM) is one of the most attractive approaches to this. The present review summarizes the historical development of this approach over the last 20 years, and shows that current methodology is based on the existence of leukemia-associated patterns of derangement in antigen expression with respect to normal differentiation or location of occurrence.

Nondisjunction of chromosomes leading to hyperdiploid childhood B-cell precursor acute lymphoblastic leukemia is an early event during leukemogenesis.

A hyperdiploid karyotype is found in 30% of B-cell precursor acute lymphoblastic leukemias in childhood. The time of nondisjunction of chromosomes leading to hyperdiploidy during leukemogenesis is unknown. We used the 3 clonotypic immunoglobulin heavy chain (IgH) gene rearrangements as molecular markers for each of the 3 chromosomes 14 in a case with hyperdiploid acute lymphoblastic leukemia to define the order of events-namely, somatic recombination and nondisjunction of chromosomes-during leukemia development.

Detection of minimal residual disease identifies differences in treatment response between T-ALL and precursor B-ALL.

We performed sensitive polymerase chain reaction-based minimal residual disease (MRD) analyses on bone marrow samples at 9 follow-up time points in 71 children with T-lineage acute lymphoblastic leukemia (T-ALL) and compared the results with the precursor B-lineage ALL (B-ALL) results (n = 210) of our previous study. At the first 5 follow-up time points, the frequency of MRD-positive patients and the MRD levels were higher in T-ALL than in precursor-B-ALL, reflecting the more frequent occurrence of resistant disease in T-ALL. Subsequently, patients were classified according to their MRD level at time point 1 (TP1), taken at the end of induction treatment (5 weeks), and at TP2 just before the start of consolidation treatment (3 months).

Low frequency of clonotypic Ig and T-cell receptor gene rearrangements in t(4;11) infant acute lymphoblastic leukaemia and its implication for the detection of minimal residual disease.

Infant t(4;11) acute lymphoblastic leukaemia (ALL) is a rare but cytogenetically well defined subgroup of immature B-cell precursor (BCP) ALL. To date, the configuration of their antigen receptor genes has not been studied in a large group of patients so far. In this study on 27 t(4;11) infant ALL, we have used standardized primer sets for the detection of all incomplete and complete immunoglobulin (Ig) heavy chain (IGH) rearrangements, as well as for the Ig light chain kappa (IGK), T-cell receptor delta (TCRD) and gamma (TCRG) rearrangements that are most common in childhood BCP ALL.

Influence of transplantation regimen on prognostic significance of high-level minimal residual disease before allogeneic stem cell transplantation in children with ALL.

High MRD levels before transplantation in children receiving T cell-depleted unrelated grafts for relapsed ALL were associated with a 100% relapse risk. We report on two children with relapsed ALL who underwent non T cell-depleted BMT from unrelated donors. Despite a high residual tumor load pre- transplant and the occurrence of only aGVHD grade I, they are still in second complete remission 2.

Presence of N regions in the clonotypic DJ rearrangements of the immunoglobulin heavy-chain genes indicates an exquisitely short latency in t(4;11)-positive infant acute lymphoblastic leukemia.

Childhood acute lymphoblastic leukemia (ALL) is frequently initiated in utero at a time of developmentally regulated insertion of N regions into the DJ(H) rearrangements of immunoglobulin heavy-chain (Ig(H)) genes. Here it is shown that N regions are present in the clonotypic DJ(H) rearrangements in 11 of 12 infant ALLs with t(4;11). These data are compared with the 122 previously published DJ(H) sequences and were found to have a pattern similar to that of ALL in children older than 3 years at diagnosis but were unlike that in children younger than 3 years who predominantly lack N regions.

Origins of "late" relapse in childhood acute lymphoblastic leukemia with TEL-AML1 fusion genes.

Approximately 20% of childhood B-precursor acute lymphoblastic leukemia (ALL) has a TEL-AML1 fusion gene, often in association with deletions of the nonrearranged TEL allele. TEL-AML1 gene fusion appears to be an initiating event and usually occurs before birth, in utero. This subgroup of ALL generally presents with low- or medium-risk features and overall has a very good prognosis.