Genomic gain at 6p21: a new cryptic molecular rearrangement in secondary myelodysplastic syndrome and acute myeloid leukemia.

Fluorescence in situ hybridization and comparative genomic hybridization characterized 6p rearrangements in eight primary and in 10 secondary myeloid disorders (including one patient with Fanconi anemia) and found different molecular lesions in each group. In primary disorders, 6p abnormalities, isolated in six patients, were highly heterogeneous with different breakpoints along the 6p arm. Reciprocal translocations were found in seven. In the 10 patients with secondary acute myeloid leukemia/myelodysplastic syndrome (AML/MDS), the short arm of chromosome 6 was involved in unbalanced translocations in 7. The other three patients showed full or partial trisomy of the 6p arm, that is, i(6)(p10) (one patient) and dup(6)(p) (two patients). In 5/7 patients with unbalanced translocations, DNA sequences were overrepresented at band 6p21 as either cryptic duplications (three patients) or cryptic low-copy gains (two patients). In the eight patients with cytogenetic or cryptic 6p gains, we identified a common overrepresented region extending for 5-6 megabases from the TNF gene to the ETV-7 gene. 6p abnormalities were isolated karyotype changes in four patients. Consequently, in secondary AML/MDS, we hypothesize that 6p gains are major pathogenetic events arising from acquired and/or congenital genomic instability.

Prognostic value of minimal residual disease (MRD) in acute myeloid leukemia (AML) with favorable cytogenetics [t(8;21) and inv(16)].

Most patients with acute myeloid leukemia (AML) and t(8;21) or inv(16) have a good prognosis with current anthracycline- and cytarabine-based protocols. Tandem analysis with flow cytometry (FC) and real-time RT-PCR (RQ-PCR) was applied to 55 patients, 28 harboring a t(8;21) and 27 an inv(16), including one case with a novel CBFbeta/MYH11 transcript. A total of 31% (n=17) of CR patients relapsed: seven with t(8;21) and 10 with inv(16). The mean amount of minimal residual disease (MRD) detected by FC in relapsed and nonrelapsed patients was markedly different: 0.3 vs 0.08% (P=0.002) at the end of treatment. The mean number of fusion transcript copies/ ABL x 10(4) also differed between relapsed and non-relapsed patients: 2385 vs 122 (P=0.001) after induction, 56 vs 7.6 after intensification (P=0.0001) and 75 vs 3.3 (P=0.0001) at the end of chemotherapy. Relapses were more common in patients with FC MRD level >0.1% at the end of treatment than in patients with < or = 0.1%: cumulative incidence of relapse (CIR) was 67 and 21% (P=0.03), respectively. Likewise, using RQ-PCR, a cutoff level of >10 copies at the end of treatment correlated with a high risk of relapse: CIR was 75% for patients with RQ-PCR >10 compared to 21% for patients with RQ-PCR levels < or = 10 (P=0.04). Combined use of FC and RQ-PCR may improve MRD detection, and provide useful clinical information on relapse kinetics in AML patients.

A variant translocation t(2;18) in follicular lymphoma involves the 5' end of bcl-2 and Ig kappa light chain gene.

We have examined three cases of human lymphoma bearing a t(2;18)(p11;q21) chromosome translocation. The bcl-2 gene appeared to be rearranged in all three cases and breakpoints were clustered in the 5' flanking region of the gene. In all three cases, bcl-2 was juxtaposed to J segments of the Ig kappa gene. This juxtaposition of the bcl-2 and Ig kappa genes is very similar to the variant chromosome translocations of Burkitt lymphoma that juxtapose the c-myc locus to IgL genes.

Genetic abnormalities associated with the t(12;21) and their impact in the outcome of 56 patients with B-precursor acute lymphoblastic leukemia.

The ETV6/RUNX1 rearrangement is found in 20-30% of children with B-cell precursor acute lymphoblastic leukemia and is associated with a good outcome. To determine the cytogenetic and molecular abnormalities associated with the ETV6/RUNX1 rearrangement and the influence of this rearrangement in patients' evolution, we analyzed the molecular cytogenetic profiles of 56 children with this rearrangement and B-cell precursor acute lymphoblastic leukemia. Secondary changes detected with conventional cytogenetics and with fluorescence in situ hybridization were found in 71.4% of cases, the most frequent being the loss of the normal ETV6 allele, 12p aberrations, duplication of the fusion gene, and trisomy 21, as in replicating the results of previous studies. In this preliminary series, with a mean follow-up of 69.3 months, secondary abnormalities did not influence patients' outcome. It seems therefore that the prognostic value of the t(12;21) does not vary and that ETV6/RUNX1 rearrangement is an independent indicator of good prognosis.

MEIS 1 expression is downregulated through promoter hypermethylation in AML1-ETO acute myeloid leukemias.

Retroviral insertional mutagenesis in BXH2 mice commonly induces myeloid leukemias. One of the most frequently involved genes in experimental studies is Meis 1. In contrast to other genes in murine models, Meis 1 has not been affected by recurrent chromosomal translocations or point mutations in human leukemias. We found a constant downregulation of the Meis 1 gene mRNA in AML1-ETO acute myeloid leukemias and in those cases harboring in frame mutations in the bZIP domain of CEBPalpha. The absence of the Meis 1 mRNA was not caused by inactivating point mutations in the coding sequence. Promoter hypermethylation was present in more than half of the cases (9/14), including samples obtained from the widely employed Kasumi-1 cell line. Double treatment with 5-Aza-2'-deoxycytidine and trichostatin A of the Kasumi-1 cell line partially reverses Meis 1 inhibition. HoxA9 levels were also low. In a cell line model (U937 Tet AML1-ETO), AML1-ETO expression was not associated with Meis 1 suppression at 72 h. Nevertheless, Meis 1 repression is dependent on the AML1-ETO transcript levels in treated leukemic patients. Chimeric products that arise from chromosomal translocations may be associated with locus-specific epigenetic inactivation. It remains to be investigated when this methylation process is acquired and which are the basic mechanisms underlying these molecular events in AML1-ETO and CEBPalpha-mutated AML.

A new human cell line with pre-B cell phenotype and t(5;12).

A new cell line (LR10.6) with pre-B cell phenotype has been established from bone marrow cells obtained from a child with B lineage acute lymphoblastic leukemia in complete clinical remission. The line expresses nuclear TdT enzyme, cytoplasmic Ig lambda-chain and membrane mu-chain and other B but no T or myeloid markers. The cells also show activation antigens CD69 and CD71, adhesion molecules CD54, CD50 and CD56 and the tyrosine kinase receptor CD117. No expression of multidrug resistance phenotype MDR-1 is observed on these cells which nevertheless express the transcriptional factor p53 protein in a mutant form. Cytogenetic study shows a translocation t(5;12)(q31;p13) involving breakpoints which contain the growth factor interleukin 3 gene (5q31) and the recently identified TEL/ETV6 gene (12p13). Activation of the cells with phorbol-12 myristate 13-acetate (PMA) up-regulates the expression of the CD69 activation antigen and down-regulates the CD117 molecule. In addition, PMA fails to induce the CD20 B cell antigen.

Oligoblastic leukaemia with (8;21) translocation and haemophagocytic syndrome and granulocytic cannibalism.

We report a 47-year-old man with oligoblastic leukaemia (8;21) translocation, phenomenon of cannibalism by granulocytic cells and haemophagocytic syndrome. The patient responded to intensive chemotherapy with disappearance of haemophagocytosis, granulocytic and histiocytic. We conclude that: (1) granulocytic cannibalism and haemophagocytic syndrome can be unusual myelodysplastic features; (2) the oligoblastic leukaemia with presence of cytogenetic abnormalities related to AML in young patients are probably more close to acute leukaemia than to myelodysplastic syndrome.

Mini-ICE regimen as mobilization therapy for chronic myelogenous leukaemia patients at diagnosis.

Between April 1996 and May 1998, 20 consecutive patients with Ph chromosome-positive CML in first chronic phase without an HLA-identical sibling received the mini-ICE regimen shortly after diagnosis to mobilize progenitor cells into the peripheral blood (PBPCs). The sex distribution was 12 males and eight females and the median (range) age 48.5 (22-62) years. The time interval between diagnosis and mobilization was a median (range) of 2 (0-5) months. Leukaphereses were initiated during recovery from chemotherapy-induced aplasia. A median number of 3 (1-7) aphereses per patient were performed to collect >/=2.0 x 106 CD34+cells/kg. Cytogenetic analysis was performed on the aphereses products of 18 patients. Complete cytogenetic Ph chromosome negativity was observed in four patients, nine had a partial negativity, three a minimal negativity and two no negative cells. Southern blot for bcr-abl was negative in the remaining two patients but the polymerase chain reaction analysis was positive. Following reinfusion, severe neutropenia was present for a median of 8.5 (3-19) days and severe thrombocytopenia lasted a median of 8 (3-18) days. Ten patients did not develop febrile neutropenia with four of them being treated on an outpatient basis. Treatment-related mortality was not observed. In conclusion, our experience demonstrates the feasibility of mobilizing PBPCs shortly after the diagnosis of CML with a safe regimen. Of note, mini-ICE allowed the collection of apheresis products with at least a major component of Ph-negative cells in almost 75% of the patients.

Mobilization of peripheral stem cells with intensive chemotherapy (ICE regimen) and G-CSF in chronic myeloid leukemia.

Seventeen patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) were treated with the ICE regimen plus G-CSF with the aim of mobilizing and collecting Ph-negative peripheral stem cells (PSC) in the setting of an autotransplant program. Fifteen patients had CML in first chronic phase (CP), and two in accelerated phase (AP). Three patients had been previously treated with interferon alpha 2a (IFN). Twelve patients underwent leukaphereses and a mean of 4.7 x 10(8)/kg mononuclear cells were obtained. Four CP patients did not show a significant mobilization peak of CD34+ cells and leukapheresis was not performed; finally, one patient died before apheresis could be performed. Six of the 12 who underwent leukaphereses obtained more than 1.0 x 10(6)/kg CD34+ cells. Eight of the 12 mobilized patients (67%) obtained a major cytogenetic response, including two complete and six partial; in the remaining four patients minimal or absent cytogenetic responses were observed. A higher rate of Ph purging was obtained in patients mobilized early or showing residual Ph-negative cells before mobilization, even if they were in AP. Infectious complications were frequent with a 38% rate of bacteremia recorded and one case of pulmonary aspergillosis resulting in a toxicity similar to that occurring in acute myeloid leukemia-induction chemotherapy. The ICE regimen can promote 'in vivo' purging of the Ph+ cells in 67% of CML mobilized patients (8/12). Failure of mobilization occurs in 65% of patients (11/17), mainly because of poor CD34+ cell yield.

Usefulness and reproducibility of cytomorphologic evaluations to differentiate myeloma from monoclonal gammopathies of unknown significance.

We attempted to differentiate monoclonal gammopathies of unknown significance (MGUS) and multiple myeloma (MM) on morphologic grounds and to determine interobserver reproducibility of the differentiation. Cytologists blindly evaluated bone marrow smears from 154 patients with bone marrow plasmacytosis for the proportion of plasma cells with predefined cellular atypias. The single morphologic characteristic that most strongly differentiated MM from MGUS was the presence of nucleoli. The percentage of plasma cells, cytoplasmic contour irregularities, and anisocytosis also predicted a diagnosis of myeloma in multivariate analysis. Six cytologists independently evaluated 68 consecutive cases to determine sensitivity and specificity of these cytomorphologic features. The interobserver coefficient of variation for the plasma cell count was 33%. On consideration of the diagnosis, 36 of 41 MGUS cases and all 24 cases of myeloma were classified correctly. The use of a predesigned score system did not present such a bias, although it did not improve overall efficiency. The plasma cell count is the most predictive characteristic of myeloma from a cytologic viewpoint, but the interobserver variability is high. Interobserver variability is also high in the assessment of morphologic atypia, and atypical traits are not uncommon in plasma cells in MGUS.

Insertion of the CCND1 gene into the IgH locus in a case of leukaemic small cell mantle lymphoma with normal chromosomes 11 and 14.

The t(11;14)(q13;q32) translocation is considered to be the cytogenetic hallmark of mantle cell lymphoma. This report describes a case of leukaemic mantle cell lymphoma in which conventional cytogenetics on stimulated peripheral blood cells showed a 46,XY, t(1;12)(p21;q23)/46,XY karyotype. Fluorescence in situ hybridisation analysis using a dual colour immunoglobulin heavy chain (IgH)/CCND1 probe showed a fusion hybridisation signal on one normal chromosome 14, indicating that an insertion of the CCND1 gene into the 14q32/IgH locus had taken place. Overexpression of the cyclin D1 protein was demonstrated on bone marrow trephine by immunohistochemical staining.

Typical CBFbeta/MYH11 fusion due to insertion of the 3'-MYH11 gene into 16q22 in acute monocytic leukemia with normal chromosomes 16 and trisomies 8 and 22.

In a case of acute monocytic leukemia, M5a according to the FAB classification, with a 48,XY,+8,+22 karyotype, amplification of the CBFbeta/MYH11 fusion transcript type A was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Fluorescence in situ hybridization (FISH) using an appropriate panel of DNA probes showed that insertion of the 3'-MYH11 within the CBFbeta gene on chromosome 16q22 was the mechanism producing the same molecular rearrangement as in typical inv(16)(p13q22)/t(16;16)(p13;q22).

MLL tandem duplication in two cases of acute myelocytic leukemia with unbalanced translocations: der(16)t(11;16)(q23;p13) and der(18)t(11;18)(q22;p11.2).

We describe two cases of acute myelocytic leukemia (AML), classified as M4 and M1 in the French-American-British classification, with unbalanced translocations der(16)t(11;16)(q23;p13) and der(18)t(11;18) (q22;p11.2), respectively. Molecular studies using Southern blot and reverse transcriptase-polymerase chain reaction showed an MLL rearrangement due to an internal duplication of the gene in both cases. Fluorescence in situ hybridization disclosed the presence of an extra copy of the MLL gene on 16p13 and 18p11.2, respectively, as a result of the partial trisomy of chromosome 11q. Our two cases clearly show that tandem duplication of the MLL gene may occur in AML with a partial 11q trisomy. Thus, systematic screening of this molecular defect should be performed in patients with unbalanced translocations involving 11q22 approximately q23-->qter.

Involvement of MLL gene in a t(10;11)(q22;q23) and a t(8;11)(q24;q23) identified by fluorescence in situ hybridization.

We describe two cases of acute myeloblastic leukemia, classified as M4 and M5 in the French-American-British nomenclature, with an 11q23 rearrangement at karyotypic analysis. The involvement of the MLL gene with two new partner loci on chromosome 10q22 and 8q24, respectively, was demonstrated by fluorescence in situ hybridization using a YAC clone B22B2L.

ETV6/RUNX1 rearrangement in childhood B-precursor acute lymphoblastic leukemia with normal karyotypes or without cytogenetic results.

The ETV6/RUNX1 rearrangement (also known as TEL/AML1) was evaluated in 39 children with B-precursor acute lymphoblastic leukemia (ALL) who had a normal karyotype or lack of mitoses. Forty-one point six percent of patients with normal karyotypes and 66.6% of patients without mitoses presented with the ETV6/RUNX1 rearrangement. In addition to this rearrangement, eight patients showed loss of the normal ETV6 allele; of three patients without mitoses, two showed an extra signal of the RUNX1 gene and the third showed the fusion gene duplicated and loss of the normal ETV6 allele. One patient without the ETV6/RUNX1 rearrangement and without mitoses showed two extra signals of the RUNX1 gene.

[DNA polymorphisms as implant markers in allogeneic bone marrow transplantation. Preliminary evaluation]. / Los polimorfismos del DNA como marcadores de implante en el trasplante alogénico de medula ósea. Valoración preliminar.

After allogeneic bone marrow transplantation (BMT), patient hematopoietic and lymphoid cells are replaced by cells derived from the donor marrow. To document and characterize successful engraftment, host and donor cells must be distinguished from each other. We have used DNA sequence polymorphism analysis in 6 patients, at times varying, to determine reliably the host or donor origin of posttransplant cell populations and to compare these results with those obtained using red blood cell antigens and cytogenetics. Initially full engraftment was documented in all patients. In 1 patient a mixed lymphohematopoietic chimerism was documented 6 months after BMT and it reverted to donor hematopoiesis at 1 year post BMT. Posttransplant leukemic relapse was studied in two patients and shown to be of host origin in both cases. The DNA restriction fragment length polymorphisms (RFLP), are a powerful tool for the documentation of engraftment after BMT, to document mixed lymphohematopoietic chimerism and for the evaluation of leukemic relapse.

Bone marrow WT1 levels at diagnosis, post-induction and post-intensification in adult de novo AML.

We retrospectively assessed whether normalized bone marrow WT1 levels could be used for risk stratification in a consecutive series of 584 acute myeloid leukemia (AML) patients. A cutoff value of 5065 copies at diagnosis identified two prognostic groups (overall survival (OS): 44 ± 3 vs 36 ± 3%, P=0.023; leukemia-free survival (LFS): 47 ± 3 vs 36 ± 4%, P=0.038; and cumulative incidence of relapse (CIR): 37 ± 3 vs 47 ± 4%, P=:0.043). Three groups were identified on the basis of WT1 levels post-induction: Group 0 (WT1 between 0 and 17.5 copies, 134 patients, OS: 59 ± 4%, LFS:59 ± 4% and CIR: 26 ± 4%); Group 1 (WT1 between 17.6 and 170.5 copies, 160 patients, OS: 48 ± 5%, LFS:41 ± 4% and CIR: 45 ± 4%); and Group 2 (WT1 >170.5 copies, 71 patients, OS: 23 ± 6%, LFS: 19 ± 7% and CIR: 68 ± 8%) (P<0.001). Post-intensification samples distinguished three groups: patients with WT1 >100 copies (47 patients, 16%); an intermediate group of patients with WT1 between 10 and 100 copies (148 patients, 52%); and a third group with WT1 <10 copies (92 patients, 32%). Outcomes differed significantly in terms of OS (30 ± 7%, 59 ± 4%, 72 ± 5%), LFS (24 ± 7%, 46 ± 4%, 65 ± 5%) and relapse probability (CIR 72 ± 7%, 45 ± 4%, 25 ± 5%), all P<0.001. WT1 levels in bone marrow assayed using the standardized ELN method provide relevant prognostic information in de novo AML.

Adverse impact of IDH1 and IDH2 mutations in primary AML: experience of the Spanish CETLAM group.

The study of genetic lesions in AML cells is helpful to define the prognosis of patients with this disease. This study analyzed the frequency and clinical impact of recently described gene alterations, isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) mutations, in a series of homogeneously treated patients with primary (de novo) AML. Two-hundred and seventy-five patients enrolled in the CETLAM 2003 protocol were analyzed. IDH1 and IDH2 mutations were investigated by well-established melting curve-analysis and direct sequencing (R140 IDH2 mutations). To establish the percentage of the mutated allele a pyrosequencing method was used. Patients were also studied for NPM, FLT3, MLL, CEBPA, TET2 and WT1 mutations. IDH1 or IDH2 mutations were identified in 23.3% AML cases and in 22.5% of those with a normal karyotype. In this latter group, mutations were associated with short overall survival. This adverse effect was even more evident in patients with the NPM or CEBPA mutated/FLT3 wt genotype. In all the cases analyzed, the normal allele was detected, suggesting that both mutations act as dominant oncogenes. No adverse clinical impact was observed in cases with TET2 mutations. IDH1 and IDH2 mutations are common genetic alterations in normal karyotype AML. Favourable genotype NPM or CEBPA mutated/FLT3 wt can be further categorized according to the IDH1 and IDH2 mutational status.