Bone Marrow WT1 Levels in Allogeneic Hematopoietic Stem Cell Transplantation for Acute Myelogenous Leukemia and Myelodysplasia: Clinically Relevant Time Points and 100 Copies Threshold Value.

The outcome of allogeneic hematopoietic stem cell transplantation (HCT) in patients with myeloid malignancies is better in those without minimal residual disease (MRD) than in those with MRD+, as assessed by multiparametric flow cytometry (MPFC). WT1 quantitation also has been used to assess the probability of relapse in acute myelogenous leukemia (AML) treated with chemotherapy. We analyzed the clinical value of normalized bone marrow WT1 levels as a measure of the expanded myeloid progenitor compartment in a consecutive series of 193 adult patients with myeloid malignancies who underwent HCT. Bone marrow WT1 levels before the HCT, at the first bone marrow aspirate after infusion, and in the follow-up samples after HCT were determined by means of real-time PCR using the European LeukemiaNet normalized method. We sought to clarify the prognostic relevance in terms of overall survival (OS), progression-free survival (PFS), and cumulative incidence of relapse (CIR). Based on earlier experience in AML, we selected a threshold of 100 copies, defining 2 groups: patients with <100 WT1 copies and those with ≥100 copies. Patients with <100 WT1 copies before HCT (median time, 36 days; range, 4 to 268 days) had a better OS, PFS, and CIR than those with ≥100 copies (40 ± 1 versus 29 ± 6 days, P = .004; 35 ± 9 versus 26 ± 6 days, P = .002; and 29 ± 7 versus 37 ± 6 days, P = .051). In the first bone marrow study after the HCT (median time, 42 days; range 14 to 157 days, respectively), patients with <100 WT1 copies also had better outcomes in terms of OS, PFS, and CIR (40 ± 7 versus 31 ± 9 days, P = .025; 36 ± 7 versus 30 ± 8 days, P = .004; and 29 ± 6 days versus 54 ± 9, P < .001, respectively). At this time point, bone marrrow samples with >100 copies also included patients who were negative for MRD as assessed by MPFC (19 of 32). During the HCT follow-up, patients with sustained WT1 levels <100 copies showed a marked benefit in terms of OS, PFS, and CIR even compared with those with only a single measurement >100 copies (mean, 68 ± 11 versus 26 ± 7 days, P < .001; 63 ± 11 versus 20 ± 8 days, P < .001; and 20 ± 8 vs. 71 ± 8 days, P < .001, respectively). Standardized bone marrow WT1 levels using a 100-copy threshold in samples obtained before HCT, at leukocyte recovery, and during follow-up provided relevant prognostic information in patients with myeloid malignacies submitted to HCT.

Feasibility of the AML profiler (Skyline™ Array) for patient risk stratification in a multicentre trial: a preliminary comparison with the conventional approach.

Deoxyribonucleic acid microarrays allow researchers to measure mRNA levels of thousands of genes in a single experiment and could be useful for diagnostic purposes in patients with acute myeloid leukaemia (AML). We assessed the feasibility of the AML profiler (Skyline™ Array) in genetic stratification of patients with de novo AML and compared the results with those obtained using the standard cytogenetic and molecular approach. Diagnostic bone marrow from 31 consecutive de novo AML cases was used to test MLL-PTD, FLT3-ITD and TKD, NPM1 and CEBPAdm mutations. Purified RNA was used to assess RUNX1-RUNX1T1, PML-RARα and CBFß-MYH11 rearrangements. RNA remnants underwent gene expression profiling analysis using the AML profiler, which detects chromosomal aberrations: t(8;21), t(15;17), inv(16), mutations (CEBPAdm, ABD-NPM1) and BAALC and EVI1 expression. Thirty cases were successfully analysed with both methods. Five cases had FLT3-ITD. In one case, a t(8;21) was correctly detected by both methods. Four cases had inv(16); in one, the RNA quality was unsatisfactory and it was not hybridized, and in the other three, the AML profiler detected the genetic lesion - this being a rare type I translocation in one case. Two cases with acute promyelocytic leukaemia were diagnosed by both methods. Results for NPM1 mutations were concordant in all but two cases (2/11, non-ABD mutations). Analysis of costs and turnaround times showed that the AML profiler was no more expensive than the conventional molecular approach. These results suggest that the AML profiler could be useful in multicentre trials to rapidly identify patients with AML with a good prognosis. Copyright © 2016 John Wiley & Sons, Ltd.

The V617F mutation of JAK2 is very uncommon in patients with thrombosis.

Given that many cases of thrombosis do not have a clear cause, a myeloproliferative disease could be involved. We investigated the V617F mutation of the JAK2 gene in 295 patients with thrombosis. Only one case was positive. Therefore, the study of this mutation is not necessary in all patients with idiopathic thrombosis.

Occurrence of the JAK2 V617F mutation in the WHO provisional entity: myelodysplastic/myeloproliferative disease, unclassifiable-refractory anemia with ringed sideroblasts associated with marked thrombocytosis.

The JAK2/V617F mutation has been noted in essential thrombocytemia. We investigated 19 cases with refractory anemia with ringed sideroblasts (RARS), including three RARS with thrombocytosis (RARS-T). Only the RARS-T patients showed this mutation. More cases need to be analyzed to determine the prevalence of the JAK2/V617F mutation in RARS-T.

[Evaluation of V617F mutation of JAK2 in negative chromosome Philadelphia chronic myeloproliferative disorders]. / Valoración de la mutación V617F del gen JAK2 en síndromes mieloproliferativos crónicos con cromosoma Filadelfia negativo.

BACKGROUND AND OBJECTIVE: Polycythemia vera (PV) and essential thrombocytemia (ET) are chronic myeloproliferative diseases (MPD) characterized by overactive hemopoiesis. A single point mutation of JAK2 (Val617Phe) has been detected in PV, ET and myelofibrosis (MF). The aim of this work was to investigate the JAK2 mutation in patients with MPD and to compare the results to those of the endogenous formation of BFU-E erythroid colonies (EEC). Finally, different sources of hematopoietic cells to obtain DNA were evaluated. PATIENTS AND METHOD: In this work 146 patents were studied (81 MPD: 27 PV, 28 ET, 11 MF and 15 with myeloid chronic leukemia). Moreover, 28 patients showed secondary polycythemias or reactive thrombocytosis, 8 MPD/myelodysplastic syndromes and 29 other disorders. In 54 patients, EEC were also evaluated. Peripheral blood cells were used as source of DNA in 122 patients, bone marrow in 33, cells from BFU-E in 14 and cells from EEC in 24 patients. Their DNA samples were analyzed using an allele-specific polimerase chain reaction methodology. RESULTS: The JAK2 mutation was present in 96% of PV patients, 59% of ET and 63.6% of MF. None of the remaining patients showed this mutation. Diagnostic agreement was excellent between EEC and the mutation (kappa index = 0.93; 97% positive agreement and 95% negative agreement). DNA was obtained in 119 out of 122 samples from peripheral blood, in all patients with bone marrow, and in 50% of patients with BFU-E or EEC. In 7 cases, samples from different cell sources were studied. Their results were identical. CONCLUSIONS: The V617F mutation of JAK2 is present in most of PV patients and half of those with MF or ET. There is an excellent concordance with the EEC results.

FLT3 mutations are associated with other molecular lesions in AML.

The basic molecular defects underlying acute myeloid leukemias (AML) seem to be caused by inactivating mutations in transcription factors which control normal myeloid differentiation (Class II mutations) and genetic lesions in tyrosine kinases resulting in constitutive activation (Class I mutations). We sought to determine the frequency of associated mutations (Class I + Class II) in a consecutive series of adult de novo AML (353 patients) in order to stress the validity of this model. Mutations and rearrangements at the FLT3, AML1/ETO, CBFbeta/MYH11, AML1, CEBPalpha and MLL genes were investigated using standard molecular methods. Despite the limitations of the study (DNA availability hampered c-kit and ras mutational analysis), 3.4% of patients showed Class I + Class II mutations. Our findings could be consistent with the cooperative model. The search for new tyrosine kinases which can be the target of molecular lesions in AML warrants further investigation.

Id4 is deregulated by a t(6;14)(p22;q32) chromosomal translocation in a B-cell lineage acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVES: Chromosome translocations resulting in gene overexpression are commonly associated with lymphoid neoplasia. Enhancer elements of the immunoglobulin or T-cell receptor (TCR) loci are abnormally located in the vicinity of the entire coding sequences of genes which exert an influence on the normal maturation and differentiation program of lymphoid cells. DESIGN AND METHODS: A patient who presented with a B-cell lineage acute lymphoblastic leukemia had a t(6;14)(p22;q32). Cytogenetic and molecular findings confirmed the involvement of IgH. Molecular cloning of the breakpoint revealed that this was located near the coding sequence of the Id4 gene, a helix-loop-helix (HLH) inhibitor protein. Alu-repeated sequences at the 6p22 end flanked a short stretch of 10 bases shared by the 6p22 and 14q32 ends, suggesting that a deletion or a looping-Alu mediated mispairing mechanism may lead to this chromosome translocation. RESULTS: Northern blot and real-time polymerase chain reaction analyses showed that the Id4 mRNA was abnormally overexpressed in this case. Only the two smaller Id4 mRNA products were detected (1.6 and 1.1 kb). Immunohistochemical analysis of Id4 protein was also assayed in a series of hematologic malignancies. Marked overexpression was found in two cases of T-cell prolymphocytic leukemias and in four B-cell lineage acute lymphoblastic leukemia including one case with the t(8;14) and another case with a p53 mutation. INTERPRETATION AND CONCLUSIONS: The Id4 gene may behave as an oncogene in some human leukemias, perhaps through its capacity to sequester specific B-cell transcription factors. A genetic recombination between Alu-repeated sequences may not be the exclusive mechanism of generating pathogenic chromosomal translocations.

Clonal heterogeneity assessed by flow cytometry in B-cell lymphomas arising from germinal centers.

Patients with mature follicular B-cell lymphomas develop aggressive non-Hodgkin lymphomas (NHLs) during disease progression. It is controversial whether most diffuse large B-cell lymphomas (DLBCLs) and Burkitt lymphomas (BLs) emerge as de novo lymphomas or from an original follicular lymphoma. To distinguish clonally related populations in aggressive NHL, we studied the immunophenotypic features of 18 consecutive samples from 16 patients. Three flow cytometric patterns were distinguished: (1) a homogeneous neoplastic population of large B cells with phenotypic features of follicular center cells; (2) 2 atypical populations of B cells, small monoclonal B cells, and large B cells with loss of some surface antigens; and (3) 2 clonal populations of small and large B cells sharing the same light-chain isotype. The 3 flow cytometric patterns were observed, respectively, in de novo DLBCL and BL, transformation into BL, and transformation into DLBCL. Flow cytometric data can provide valuable information about the natural history of NHL.

WT1 monitoring in core binding factor AML: comparison with specific chimeric products.

Minimal residual disease may help to establish clinical decisions in patients with AML. WT1 offers the possibility to analyze those cases without currently known underlying genetic abnormalities. To compare the value of chimeric specific quantitative PCR with WT1 PCR in CBF acute leukemia, 445 samples from 96 AML (49 AML1-ETO+ and 47 CBFB-MYH11+) cases were included in the study. For each sample AML1-ETO or CBFB-MYH11 levels obtained using the conditions of the BIOMED group were compared with the results of WT1 levels using sensitive primers and conditions. Simultaneously, normal range expression of WT1 was established using RNA obtained from eight healthy donors. WT1 mutations were also investigated both at RNA and at the genomic level. The majority of CBF samples showed rises in WT1 levels (88.7%) at diagnosis. However, 18% of AML1-ETO showed WT1 levels below 250 copies in contrast with 5% CBFB-MYH11 cases. WT1 mutation was not detected in any case (70 diagnostic samples). We found correlation between WT1 levels at diagnosis and the CD34 blast population estimated by flow cytometry in CBFB-MYH11+ cases. We found no association between WT1 levels and clinical outcome. There was a high concordance between chimeric transcript analysis and WT1 levels in CR patients. Concordance was also high in relapsed patients (78% in AML1-ETO and 98% in CBFB-MYH11+ cases). Both WT1 and specific chimeric transcript identified and rescued false negative results of the other test. Additional studies are needed to determine whether the rare discrepancies are a reflection of the cooperative nature of WT1 overexpression or a consequence of the uneven distribution in the leukemic population. WT1 is a powerful MRD tool even in cases with currently available molecular targets.

Uniparental disomy may be associated with microsatellite instability in acute myeloid leukemia (AML) with a normal karyotype.

The discovery of underlying genetic lesions helps to better understand the mechanisms of leukemogenesis and identify prognostic subgroups. Recent insights have allowed normal karyotype acute myeloid leukemia (AML) to be split into many molecular entities according to the genetic status of FLT3, NPM, CEBPA and MLL. Genome-wide single nucleotide polymorphism analysis was performed on 22 well-characterised AML patients with a normal karyotype. At the same time, microsatellite instability was investigated using a commonly used panel of polymorphic markers. Loss of heterozygosity (LOH) was found in 22.7% of cases without an associated copy number variation, suggesting that LOH represented an acquired partial uniparental disomy (aUPD) event. Three UPD+ cases harboured NPM mutations, associated with FLT3-ITD in two of them. An additional UPD patient had mutations both in CEBPA and in WT1. MSI was present at three loci in the three UPD+ cases (60%), whereas single locus MSI was present in three UPD- patients (17%). MSI involved the polymorphic PIG3 promoter in two UPD+ cases. It remains to be tested whether UPD and MSI association marks a common pathway of leukemogenesis.

Microsatellite instability is not an uncommon finding in adult de novo acute myeloid leukemia.

To investigate the biologic relevance of microsatellite instability (MSI) in de novo acute myeloid leukemia (AML), 102 consecutive adult patients were analyzed by using a panel of seven microsatellites (BAT25, BAT26, D13S1267, D13S174, D2S123, D5S346 and Mdf15). Frame-shift mutations in the repetitive sequences in the coding region of MSH3, MSH6, BAX, TGFBRII and IGFRII were also investigated by using a fluorescent PCR-based assay. Methylation-specific PCR was used to determine the methylation status of hMLH1 in MSI+ cases. MSH3, MSH6 and MLH1 expression was also analyzed in 68 cases by means of real-time quantitative PCR. MSI was detected in 20 cases: 14 cases had MSI-high (instability of at least two microsatellite markers) and 6 cases corresponded to MSI-low (a single polymorphic marker with instability). Six MSI+ cases showed an associated MLL rearrangement (p=0.002). No single case showed a mutation in the repetitive sequences of the MSH3, MSH6, BAX, TGFBRII and IGFRII genes. Most samples displayed low mRNA levels of the repair genes. hMLH1 promoter was hypermethylated in five MSI+ cases. Overall survival analysis revealed no adverse effect of MSI positivity. These results suggest that MSI may be a common biologic finding in de novo AML.

Bcl-6 p53 mutations in lymphomas carrying the bcl-2/Jh rearrangement.

BACKGROUND AND OBJECTIVES: The t(14;18)(q32;q21) chromosomal translocation is the hallmark of follicular lymphomas (FL). The translocation induces the overexpression of the Bcl-2 protein and prolongs the survival of clonogenic cells. Tumor cells may acquire additional molecular alterations that may be associated with histologic progression or with chemo-resistance. DESIGN AND METHODS: We analyzed the distribution and association of bcl-6 and p53 mutations in 55 consecutive bcl-2/Jh+ lymphoma samples derived from 43 patients obtained at the time of diagnosis and, in 5 of these patients, during follow-up. A total of 29 bcl-6 point mutations were detected in seventeen patients (40%) associated with major or minor breakpoints of the bcl-2/Jh fusion gene. In seven cases a p53 mutation was detected. Three cases corresponded to FL with the minor breakpoint in the bcl-2 gene and these patients had a favorable clinical evolution, whereas the 4 patients with p53 mutations and the major breakpoint had a bad clinical outcome with morphologic transformation to high-grade lymphoma in three cases. The sequential analysis of 5 patients showed a different timing in the acquisition of mutations: one patient showed bcl-6 and p53 mutations at diagnosis, another patient showed bcl-6 mutations at diagnosis and acquired a p53 mutation later whereas the third patient had a p53 mutation before the appearance of the bcl-6 mutation. RESULTS: We did not find significant differences in survival between patients with FL who showed exclusively bcl-6 mutations and those without bcl-6 mutations, but those patients with a high International Progostic Index score and p53 mutations showed the lowest overall survival (p = 0.002). INTERPRETATION AND CONCLUSIONS: These findings suggest that bcl-2/Jh lymphomas show molecular heterogeneity and that bcl-6 and p53 mutations may be acquired during the evolution of such lymphomas. Bcl-6 mutations, by themselves, do not seem to be associated with a bad prognosis. Rearrangements at the minor bcl-2 locus may have a different molecular evolution.