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BackgroundIKZF1 gene deletion is an indicator of poor prognosis in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). The AEIOP/BFM group proposed that the prognostic strength of IKZF1 deletion could be remarkably improved by taking into account additional genetic deletions and reported that among patients with an IKZF1 deletion those with deletions in CDKN2A/2B, PAX5, or PAR1 in the absence of ERG deletion, grouped as IKZF1(plus), had the worst outcome. ProcedureBetween 1998 and 2008, 1636 patients under 18 years of age with previously untreated BCP-ALL were registered in the EORTC 58951 trial. Those with multiplex ligation-dependent probe amplification data were included in this analysis. Unadjusted and adjusted Cox model was used to investigate the additional prognostic value of IKZF1(plus). ResultsAmong 1200 patients included in the analysis, 1039 (87%) had no IKZF1 deletion (IKZF1(WT)), 87 (7%) had an IKZF1 deletion but not IKZF1(plus) (IKZF1(del)) and 74 (6%) had IKZF1(plus). In the unadjusted analysis, both patients with IKZF1(del) (hazard ratio [HR] = 2.10, 95% confidence interval [CI]: 1.34-3.31) and IKZF1(plus) (HR = 3.07, 95% CI: 2.01-4.67) had a shorter event-free survival compared with IKZF1(WT). However, although the IKZF1(plus) status was associated with patients' characteristics indicating poor prognosis, the difference between IKZF1(plus) and IKZF1(del) was not statistically significant (HR = 1.46, 95% CI: 0.83-2.57, p = .19). The results of the adjusted analysis were similar to the unadjusted analysis. ConclusionsIn patients with BCP-ALL from the EORTC 58951 trial, the improvement of the prognostic importance of IKZF1 by considering IKZF1(plus) was not statistically significant.

The analysis of bone marrow (BM) samples in multiple myeloma (MM) patients can lead to the underestimation of the genetic heterogeneity within the tumor. Blood-derived liquid biopsies may provide a more comprehensive approach to genetic characterization. However, no thorough comparison between the currently available circulating biomarkers as tools for mutation profiling in MM has been published yet and the use of extracellular vesicle-derived DNA for this purpose in MM has not yet been investigated. Therefore, we collected BM aspirates and blood samples in 30 patients with active MM to isolate five different DNA types, i.e., cfDNA, EV-DNA, BM-DNA and DNA isolated from peripheral blood mononucleated cells (PBMNCs-DNA) and circulating tumor cells (CTC-DNA). DNA was analyzed for genetic variants with targeted gene sequencing using a 165-gene panel. After data filtering, 87 somatic and 39 germline variants were detected among the 149 DNA samples used for sequencing. cfDNA showed the highest concordance with the mutation profile observed in BM-DNA and outperformed EV-DNA, CTC-DNA and PBMNCs-DNA. Of note, 16% of all the somatic variants were only detectable in circulating biomarkers. Based on our analysis, cfDNA is the preferable circulating biomarker for genetic characterization in MM and its combined use with BM-DNA allows for comprehensive mutation profiling in MM.

Detection of minimal residual disease (MRD) to guide therapy has been a standard practice in treatment of childhood acute lymphoblastic leukemia (ALL) for decades. In multiple myeloma (MM), a clear correlation is found between absence of MRD and longer survival. Quantitative allele-specific oligonucleotide (qASO)-PCR is the standard molecular method for MRD detection in these hematologic malignant tumors. However, this technique has some drawbacks that can be overcome by next-generation sequencing (NGS). In this study, NGS is validated as an alternative method for qASO-PCR for MRD detection in both ALL and MM. MRD results obtained by NGS and qASO-PCR were compared in 59 and 39 bone marrow samples of 33 and 14 patients with ALL and MM, respectively. Our results indicate that the use of gBlocks as calibrators makes the NGS approach a powerful tool to quantify MRD. With an input of 400 ng of DNA (corresponding to approximately 7 × 104 cells), a limit of detection of 0.01% can be achieved. The specificity of the NGS-MRD technique was 100%, and a correlation with qASO-PCR for quantifiable MRD results of 0.93 and 0.91 was found in ALL and MM, respectively. Especially for MM, the higher applicability (100%) of the NGS-MRD protocol, compared with qASO-PCR (57%), was clearly demonstrated. These results demonstrate that NGS is an even better alternative to qASO-PCR.

High-count monoclonal B cell lymphocytosis (MBL) with a chronic lymphocytic leukemia (CLL) phenotype is a well-known entity, featuring 1–4% annual risk of progression towards CLL requiring treatment. Lymphoma-like MBL (L-MBL), on the other hand, remains poorly defined and data regarding outcome are lacking. We retrospectively evaluated 33 L-MBL cases within our hospital population and compared them to 95 subjects with CLL-like MBL (C-MBL). Diagnoses of L-MBL were based on asymptomatic B cell clones with Matutes score < 3, B cells < 5.0 × 10 3/μl, and negative computerized tomography scans. We found that median B cell counts were considerably lower compared to C-MBL (0.6 vs 2.3 × 10 3/μl) and remained stable over time. Based on immunophenotyping and immunogenetic profiling, most L-MBL clones did not correspond to known lymphoma entities. A strikingly high occurrence of paraproteinemia (48%), hypogammaglobulinemia (45%), and biclonality (21%) was seen; these incidences being significantly higher than in C-MBL (17, 21, and 5%, respectively). Unrelated monoclonal gammopathy of undetermined significance was a frequent feature, as the light chain type of 5/12 paraproteins detected was different from the clonal surface immunoglobulin. After 46-month median follow-up, 2/24 patients (8%) had progressed towards indolent lymphoma requiring no treatment. In contrast, 41% of C-MBL cases evolved to CLL and 17% required treatment. We conclude that clinical L-MBL is characterized by pronounced immune dysregulation and very slow or absent progression, clearly separating it from its CLL-like counterpart.

Key Points Intragenic PAX5 amplification defines a novel, relapse-prone subtype of B-cell precursor acute lymphoblastic leukemia with a poor outcome.

Intragenic PAX5 amplification defines a novel, relapse-prone subtype of B-cell precursor acute lymphoblastic leukemia with a poor outcome.

The aim of our study was to analyze the factors contributing to heterogeneity of prognosis in patients with hyperdiploidy50 chromosomes (HD50), a group of B-cell precursor acute lymphoblastic leukemia with favorable outcome. The 541 HD50 patients registered prospectively in the 58951 European Organisation for Research and Treatment of Cancer (EORTC) Children's Leukemia Group (CLG) trial, identified by karyotype (446 patients) and by DNA index (DI) (490 patients), had a 6-year event-free survival (EFS) of 89.0% (standard error [SE] = 1.5%) and a 6-year overall survival (OS) of 95.9% (SE = 0.9%). The strongest prognostic factor was the modal number of chromosomes (MNC): the 6-year EFS of 51-53, 54-57, and 58-66 MNC groups were 80%, 89%, and 99%, respectively (P.0001). Ploidy assessed by DI was also a favorable factor: the higher the DI, the better the outcome. The 6-year EFS of the 3 subgroups of DI1.16/≥1.16-1.24/≥1.24 were 83%, 90%, and 95%, respectively (P = .009). All usual combinations of trisomies (chromosomes 4, 10, 17, 18) were significant favorable factors but had lower EFS when MNC was lower than 58. In multivariate analysis, MNC remained the strongest factor. Consequently, the best indicator for excellent outcome was ploidy assessed by karyotype because patients with 58-66 chromosomes stood every chance of being cured (OS of 100% at 6-year follow-up) with less-intensive therapy. This trial was registered at www.clinicaltrials.gov as #NCT00003728. Registered: http://www.eortc.org/, http://clinicaltrials.gov/show/NCT00003728.

Overwhelming evidence indicates that long non-coding RNAs have essential roles in tumorigenesis. Nevertheless, their role in the molecular pathogenesis of pediatric B-cell precursor acute lymphoblastic leukemia has not been extensively explored. Here, we conducted a comprehensive analysis of the long non-coding RNA transcriptome in ETV6/RUNX1-positive BCP-ALL, one of the most frequent subtypes of pediatric leukemia. First, we used primary leukemia patient samples to identify an ETV6/RUNX1 specific expression signature consisting of 596 lncRNA transcripts. Next, integration of this lncRNA signature with RNA sequencing of BCP-ALL cell lines and lncRNA profiling of an in vitro model system of ETV6/RUNX1 knockdown, revealed that lnc-NKX2-3-1, lnc-TIMM21-5, lnc-ASTN1-1 and lnc-RTN4R-1 are truly regulated by the oncogenic fusion protein. Moreover, sustained inactivation of lnc-RTN4R-1 and lnc-NKX2-3-1 in ETV6/RUNX1 positive cells caused profound changes in gene expression. All together, our study defined a unique lncRNA expression signature associated with ETV6/RUNX1-positive BCP-ALL and identified lnc-RTN4R-1 and lnc-NKX2-3-1 as lncRNAs that might be functionally implicated in the biology of this prevalent subtype of human leukemia., SCOPUS: ar.j, info:eu-repo/semantics/published

DNA copy number analysis has been instrumental for the identification of genetic alterations in B-cell precursor acute lymphoblastic leukemia. Notably, some of these genetic defects have been associated with poor treatment outcome and might be relevant for future risk stratification. In this study, we characterized recurrent deletions of CD200 and BTLA genes, mediated by recombination-activating genes, and used breakpoint-specific polymerase chain reaction assay to screen a cohort of 1154 cases of B-cell precursor acute lymphoblastic leukemia uniformly treated according to the EORTC-CLG 58951 protocol. CD200/BTLA deletions were identified in 56 of the patients (4.8%) and were associated with an inferior 8-year event free survival in this treatment protocol [70.2% ± 1.2% for patients with deletions versus 83.5% ± 6.4% for non-deleted cases (hazard ratio 2.02; 95% confidence interval 1.23-3.32; P=0.005)]. Genetically, CD200/BTLA deletions were strongly associated with ETV6-RUNX1-positive leukemias (P

High-dose therapy (HDT) and autologous transplantation prolongs remission duration and survival in multiple myeloma (MM), but relapse still occurs at a median of 2 years post-HDT. In order to investigate whether the number of residual tumour cells in the bone marrow (BM) after transplantation can predict the duration of response, a quantitative allele-specific oligonucleotide polymerase chain reaction (qASO-PCR) assay was used to measure tumour load in BM at 3-6 months post-HDT in 67 patients. The method of maximally selected log-rank statistics was used to test for the existence of a cut-off value in the BM tumour load data set. A cut-off value with respect to progression-free survival (PFS) was identified (P = 0.001). The estimated threshold for placing patients into a "good" or "bad" prognostic group was 0.015% (n = 22 and 38 respectively) with a median PFS of 64 months vs. 16. Multivariate analysis showed grouping by PCR result to be an independent prognostic factor for PFS (estimated hazard ratio after shrinkage, 3.91). This study identifies for the first time a threshold of the post-HDT tumour load with prognostic significance for PFS in MM. Quantitative molecular assessment thus may help to identify those patients who are in need of further treatment early after autologous transplantation.

Recently it was reported that Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) infects bone marrow (BM) dendritic cells (DC) in multiple myeloma (MM) patients and therefore might play a role in MM development. Because of the use of myeloid growth factors like GM-CSF and G-CSF for the mobilization of peripheral blood progenitor cells (PBPC), the subsequent increase of DC precursors might imply a risk for KSHV contamination in PBPC grafts. Therefore, in this study leukapheresis products and ex vivo cultured CD34+ cell suspensions were analysed. KSHV DNA could not be amplified in any of them.

Background and Methods The implications of the detection of residual disease after treatment of acute lymphoblastic leukemia (ALL) are unclear. We conducted a prospective study at 11 centers to determine the predictive value of the presence or absence of detectable residual disease at several points in time during the first six months after complete remission of childhood ALL had been induced. Junctional sequences of T-cell–receptor or immunoglobulin gene rearrangements were used as clonal markers of leukemic cells. Residual disease was quantitated with a competitive polymerase-chain-reaction (PCR) assay. Of 246 patients enrolled at diagnosis and treated with a uniform chemotherapy protocol, 178 were monitored for residual disease with one clone-specific probe (in 74 percent) or more than one probe (in 26 percent). The median follow-up period was 38 months. Results The presence or absence and level of residual leukemia were significantly correlated with the risk of early relapse at each of the times studi...

The development of an immune response towards factor VIII (fVIII) remains a major complication for hemophilia A patients receiving fVIII infusions. The design of a specific therapy to restore unresponsiveness to fVIII has been hampered by the diversity of the anti-fVIII antibody. Molecular analysis of the specific immune response is therefore required. To this end, we have characterized an fVIII-specific human IgG4κ monoclonal antibody (BO2C11) produced by a cell line derived from the memory B-cell repertoire of a hemophilia A patient with inhibitor. BO2C11 recognizes the C2 domain of fVIII and inhibits its binding to both von Willebrand factor (vWF) and phospholipids. It completely inhibits the procoagulant activity of native and activated fVIII, with a specific activity of approximately 7,000 Bethesda units/mg. vWF reduces the rate of fVIII inactivation by BO2C11. The antibody-fVIII association rate constant (kass ∼7.4 × 105M−1 s−1) is eightfold lower than that for vWF-fVIII association, whereas its dissociation rate constant (kdiss ≤1 × 10−5s−1) is 100-fold lower than that for the vWF-fVIII complex, which suggests that BO2C11 almost irreversibly neutralizes fVIII after its dissociation from vWF. BO2C11 is the first human monoclonal anti-fVIII IgG antibody that has been isolated and allows the study of fVIII inactivation at the molecular level.

The development of an immune response towards factor VIII (fVIII) remains a major complication for hemophilia A patients receiving fVIII infusions. The design of a specific therapy to restore unresponsiveness to fVIII has been hampered by the diversity of the anti-fVIII antibody. Molecular analysis of the specific immune response is therefore required. To this end, we have characterized an fVIII-specific human IgG4κ monoclonal antibody (BO2C11) produced by a cell line derived from the memory B-cell repertoire of a hemophilia A patient with inhibitor. BO2C11 recognizes the C2 domain of fVIII and inhibits its binding to both von Willebrand factor (vWF) and phospholipids. It completely inhibits the procoagulant activity of native and activated fVIII, with a specific activity of approximately 7,000 Bethesda units/mg. vWF reduces the rate of fVIII inactivation by BO2C11. The antibody-fVIII association rate constant (kass ∼7.4 × 105M−1 s−1) is eightfold lower than that for vWF-fVIII association, whereas its dissociation rate constant (kdiss ≤1 × 10−5s−1) is 100-fold lower than that for the vWF-fVIII complex, which suggests that BO2C11 almost irreversibly neutralizes fVIII after its dissociation from vWF. BO2C11 is the first human monoclonal anti-fVIII IgG antibody that has been isolated and allows the study of fVIII inactivation at the molecular level.

Oncogenic subtypes in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are used for risk-stratification. However, a significant number of BCPALLpatients are still genetically unassigned. Using array-CGH in a selected BCPALL cohort, we characterized a recurrent V(D)J-mediated intragenic deletion of the ERG gene (ERGdel). A breakpoint-specific PCR assay was designed and used to screen an independent non-selected cohort of 897 children aged 1-17 years treated for BCP-ALL in the EORTC-CLG 58951 trial. ERGdel was found in 29/897 patients (3.2%) and was mutually exclusive of known classifying genetic lesions, suggesting that it characterized a distinct leukemia entity. ERGdel was associated with higher age (median 7.0 years vs. 4.0 years, P=0.004), aberrant CD2 expression (43.5% vs. 3.7%, P

Oncogenic subtypes in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are used for risk stratification. However, a significant number of BCP-ALL patients are still genetically unassigned. Using array-comparative genomic hybridization in a selected BCP-ALL cohort, we characterized a recurrent V(D)J-mediated intragenic deletion of the ERG gene (ERG(del)). A breakpoint-specific PCR assay was designed and used to screen an independent non-selected cohort of 897 children aged 1-17 years treated for BCP-ALL in the EORTC-CLG 58951 trial. ERG(del) was found in 29/897 patients (3.2%) and was mutually exclusive of known classifying genetic lesions, suggesting that it characterized a distinct leukemia entity. ERG(del) was associated with higher age (median 7.0 vs. 4.0 years, P=0.004), aberrant CD2 expression (43.5% vs. 3.7%, P

Staphylococcus enterotoxins bind class II MHC molecules on antigen presenting cells (APC) and stimulate T cells expressing appropriate V beta gene products. Although the role of non-TCR associated co-stimulatory receptors during antigen-specific T cell stimulation has been clearly established, the involvement of co-stimulatory activity in T cell activation by superantigens has been the matter of controversy. In this report, we examine the role of co-stimulation provided by selected APC populations in the response to bacterial exotoxins (staphylococcal enterotoxin A, staphylococcal enterotoxin B and toxic shock syndrome type 1). We demonstrate that the APC population able to activate naive T cells to IL-2 production is heterogeneous, comprising both adherent (presumably dendritic) and non-adherent (mostly B lymphocytes) cells. By stimulating naive T cells in the presence of graded doses of superantigens, we have observed that half-maximal IL-2 production was achieved at lower doses of superantigens in the presence of dendritic cells. Similarly, addition of antibodies to CD28 or B7.1-transfected cell lines increased the sensitivity of naive T cells to lower doses of superantigens. These observations indicate therefore that superantigens can be presented to naive T cells by APC displaying distinct levels of co-stimulatory activity, although with different efficacy. Thus, naive T cells are sensitive to CD28-mediated co-stimulation during superantigen-mediated responses but IL-2 production can be induced by high doses of superantigens in the presence of APC expressing weak co-stimulatory activity. These observations are compatible with the hypothesis that CD28-mediated signals participate in T cell activation by lowering T cell sensitivity to TCR ligands.

MicroRNAs (miRNAs) are small RNA molecules that negatively regulate gene expression at the post transcriptional level. Over the past few years, these miRNAs have been shown to be widely involved in diverse biological processes, like apoptosis, cell metabolism and cancer. The aim of this study was to compare the miRNA expression in multiple myeloma plasma cells to that in their normal counterparts. A subset of ten miRNAs was chosen based upon evidence in the literature for their role in tumorigenesis with special emphasis on B cell malignancies. The expression of mature miRNAs was examined with quantitative real-time reverse transcription based polymerase chain reaction (TaqMan®MicroRNA assay) in 7 human multiple myeloma (MM) cell lines, in purified bone marrow derived plasma cells from 4 MM patients, one MGUS patient and 3 healthy adults. The plasma cells from patients and controls were positively selected using CD138-coated microbeads. Our results showed that miR-15a and miR-21 were equally expressed in cell lines, patients and healthy controls. Therefore, these 2 miRNAs were used for normalization. All data were compared with the data derived from normal plasma cells. Higher expression was seen for let-7a, miR-16 and 2 members of the miR-17 cluster (miR-17-5p and miR-19b) both in MM patients and cell lines. Expression of miR-16 was much higher in the MM plasma cells than in the MGUS plasma cells (only one sample). The miR-181a showed a heterogeneous expression in cell lines but was normally expressed in patients. The miR-372 expression was below the level of accurate quantification in all samples. There was a dramatic difference between the stroma dependent (MM5.1) and the stroma independent cell line (MM5.2) in miR-155 expression. The miR-143 was less abundant in all cell lines and in one MM sample that contained more than 90% plasma cells. Interestingly, the MM5.2 cell line, which is stroma independent, reflecting a more aggressive MM stage, showed also a much lower expression for miR-143 than the stroma dependent counterpart (MM5.1). In summary, the results of this study show that there is a difference in miRNA expression between MM plasma cells and their healthy counterparts and also between more and less aggressive MM plasma cells, suggesting that miRNAs could play a role in disease onset and progression.

Background and Objectives Mesenchymal stem cells (MSC) are adult stem cells that can be expanded many fold in vitro and have the therapeutic potential to restore the bone marrow microenvironment and support hematopoietic recovery after myeloablative conditioning for hematopoietic stem cell transplantation. Successful homing to the target tissue, such as bone marrow, implies that MSC are able to extravasate after systemic administration. However, the extravasation capacity of MSC and the underlying mechanisms are poorly understood to date. We studied in vitro the capacity of MSC to migrate through bone marrow endothelium.Design and Methods In vitro invasion and transendothelial migration assays were performed. The expression of matrix metalloproteinase (MMP) was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and zymography. Migration of cells cultured at high or low confluence was compared and differential gene expression in these conditions was analyzed with microarray and real-time RT-PCR. The functional involvement in MSC migration was assessed using neutralizing anti-MMP-2 antibody, MMP-2 short interfering RNA or recombinant tissue inhibitor of metalloproteinase (TIMP-3).Results We demonstrated that MSC can invade reconstituted basement membrane and that bone marrow endothelial cells stimulate this process. We also showed that the transendothelial migration of MSC is at least partially regulated by MMP-2. High culture confluence was found to increase production of the natural MMP-inhibitor TIMP-3 and decrease transendothelial migration of MSC.Interpretation and Conclusions We show that MSC have the potential to migrate through bone marrow endothelium and that this process involves MMP-2. Moreover, the migration of MSC is significantly influenced by the level of culture confluence. Increased culture confluence impairs migration and is related to an upregulation of TIMP-3. The therapeutic use of MSC would benefit from a selection of culture conditions that allow optimal extravasation of these cells.

Background and Objectives Mesenchymal stem cells (MSC) are adult stem cells that can be expanded many fold in vitro and have the therapeutic potential to restore the bone marrow microenvironment and support hematopoietic recovery after myeloablative conditioning for hematopoietic stem cell transplantation. Successful homing to the target tissue, such as bone marrow, implies that MSC are able to extravasate after systemic administration. However, the extravasation capacity of MSC and the underlying mechanisms are poorly understood to date. We studied in vitro the capacity of MSC to migrate through bone marrow endothelium. Design and Methods In vitro invasion and transendothelial migration assays were performed. The expression of matrix metalloproteinase (MMP) was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and zymography. Migration of cells cultured at high or low confluence was compared and differential gene expression in these conditions was analyzed with microarray and real-time RT-PCR. The functional involvement in MSC migration was assessed using neutralizing anti-MMP-2 antibody, MMP-2 short interfering RNA or recombinant tissue inhibitor of metalloproteinase (TIMP-3). Results We demonstrated that MSC can invade reconstituted basement membrane and that bone marrow endothelial cells stimulate this process. We also showed that the transendothelial migration of MSC is at least partially regulated by MMP-2. High culture confluence was found to increase production of the natural MMP-inhibitor TIMP- 3 and decrease transendothelial migration of MSC. Interpretation and Conclusions We show that MSC have the potential to migrate through bone marrow endothelium and that this process involves MMP-2. Moreover, the migration of MSC is significantly influenced by the level of culture confluence. Increased culture confluence impairs migration and is related to an upregulation of TIMP-3. The therapeutic use of MSC would benefit from a selection of culture conditions that allow optimal extravasation of these cells.

BACKGROUND AND OBJECTIVES: This European Group for Blood and Marrow Transplantation (EBMT) multicentre randomized phase III study was designed to assess the safety and efficacy of CD34+ selection in newly diagnosed myeloma patients undergoing autologous transplantation. DESIGN AND METHODS: One hundred and eleven patients responsive to initial chemotherapy were randomized to receive CD34+ selected (arm A) or unselected PBPC (arm B) after conditioning with high-dose melphalan and TBI. ASO-PCR was used to assess purging efficacy and reinfused tumor load. Tumor load could be assessed in 59 patients. RESULTS: CD34+ selection gave a median tumor cell depletion of 2.2 logs (0.77-5.96). No tumor cells were detected in products infused in 17/26 (A) and 5/33 (B) patients. The five year overall survival (OS), event free survival (EFS) and relapse rate (RR) were 51%, 20% and 80% in arm A and 45%, 18% and 80% in arm B respectively with no significant difference between the two groups. Thirteen patients in arm A and 2 in arm B experienced episodes of serious early infection (p=0.02). There were 3 early transplant related deaths in A but none in B. INTERPRETATION AND CONCLUSIONS: Despite significant tumor cell reduction, CD34+ selection does not reduce RR and increases the risk of severe post-transplant infections. There was also no difference in RR between patients in either arm who received grafts with detectable tumor cells and those receiving grafts with no detectable tumor cells, suggesting that reinfused tumor cells may not be the main cause of relapse after autologous transplant in myeloma.

MM is a B-cell malignancy mainly characterized by monoclonal expansion of plasma cells in the BM, presence of paraprotein in serum and occurrence of osteolytic bone lesions. MMPs are a family of proteolytic enzymes that can contribute to cancer growth, invasion, angiogenesis, bone degradation and other processes important in the pathogenesis of MM. We investigated MMP-9 production in the 5T33MM murine model. Expression of MMP-9 protein in supernatant and cell extracts was analyzed by gelatin zymography. The in vitro, stroma-independent variant 5T33MMvt showed no protein expression of MMP-9 in contrast to in vivo growing MM cells, 5T33MMvv. However, when 5T33MMvt cells were injected into naive mice and isolated after tumor take (5T33MMvt-vv), they secreted a significant amount of MMP-9. These results were confirmed by specific staining of cytospins with an anti-MMP-9 antibody. The MMP-9 production by 5T33MMvt-vv cells disappeared when the cells were recultured in vitro. These data demonstrated that upregulation of MMP-9 occurs in vivo and that this process is dependent on the microenvironment. Cocultures of 5T33MMvt cells with STR10 BMECs induced MMP-9 in MM cells, as determined by both gelatin zymography and flow-cytometric analysis. In conclusion, our results demonstrate that MMP-9 production by MM cells is upregulated in vivo by the interaction of MM cells with BMECs.

In the peripheral blood (PB) of multiple myeloma (MM) patients, clonotypic B cells are present that express the identical V(D)J rearrangements as the malignant plasma cells in the bone marrow. In the present study, the proliferative capacity of clonotypic B cells from MM patients (n = 10) and the ability to differentiate in vitro was determined using the CD40-culturing system. For six patients, the presence of clonotypic B cells expressing variant immunoglobulin (Ig) isotypes was assessed by Ig isotype-specific allele-specific oligonucleotide reverse transcription polymerase chain reaction (ASO-RT-PCR) after culturing with CD40L and interleukin 4 (IL-4). In three out of six patients, clonotypic B cells expressing variant isotypes were detected both before and after culturing. The ability of clonotypic B cells to undergo B-cell differentiation was studied by abrogating CD40 signalling accompanied by IL-10 and IL-2 stimulation, enhancing differentiation towards Ig-secreting cells. The numbers of clonotypic Bcells were determined by quantitative ASO-PCR. An increase in cell number was observed upon CD40L and IL-4 stimulation, whereas the relative number of clonotypic B cells was unaltered. In contrast, upon B-cell differentiation the relative number of clonotypic B cells decreased. In conclusion, clonotypic B cells can be cultured and isolated in vitro using the CD40 system. Clonotypic B cells responded to CD40 triggering in a similar fashion as to non-clonotypic normal B cells. However, the ability of clonotypic B cells to undergo in vitro activation and differentiation into Ig-secreting cells is hampered.

Interaction of the CD40L (CD154) molecule on activated T cells with its receptor, CD40, on macrophages and dendritic cells (DC) provides a strong signal for interleukin (IL)-12 production. As IL-12 is the most important factor in driving Th precursor (Thp) cells into T(h)elper 1 cells, CD40-CD40L interactions strongly promote Th1 differentiation. Th2 cytokines (IL-4, IL-13, IL-10) on the other hand, are known to inhibit Th1 differentiation, and to promote either directly or indirectly, Th2 differentiation. Inhibition of lipopolysaccharide (LPS)-induced IL-12 production by IL-4, IL-13 and IL-10 is supposed to be one such mechanism. However, we here report that IL-4 and IL-13 enhance p70 IL-12 production and p40 mRNA transcription by human monocytes when the latter are stimulated trough triggering of CD40. This effect on IL-12 induction is most clear in the presence of interferon (IFN)-gamma, which upregulates CD40 expression. IL-10 potently inhibits IL-12 production. The increased IL-12 production in the presence of IL-4 and IL-13 is however, not the indirect result of a reduction in IL-10 production, but is most likely owing to a direct effect of IL-4 and IL-13. We conclude that IL-4 and IL-13 enhance rather than decrease the IL-12 production by human monocytes during interaction with T cells. This effect can potentially contribute in vivo to switching of an ongoing Th2 response towards a Th1 response and the findings also support the dominant effect of CD40/CD40L interaction on Th1 development, even in the presence of Th2 cytokines.

The purpose of this work was to study the clonal relationship between the cells that secrete monoclonal proteins in an IgA/ IgE double multiple myeloma patient. Double monoclonal gammopathy is a rare condition in which two types of monoclonal proteins can be found in the serum and/or urine of patients with multiple myeloma or gammopathy of undetermined significance. The study of the relationship between the cells expressing the different monoclonal proteins may provide insight in the pathogenesis of these disorders.The clonal relationship of the two tumoral plasma cell populations was examined by immunophenotyping and sequence analysis of the variable regions of the immunoglobulin heavy chain genes. Both immunoglobulin sequences were isolated from the bone marrow using a polymerase chain reaction (PCR)-based cloning strategy. Rare isotype-switch variants were detected by a myeloma-specific PCR in combination with different isotype-specific primers. An in vitro culture system, based on the activation of the CD40 molecule on the B cell, was used in order to isolate and expand myeloma-related B cells from peripheral blood that could possibly be regarded as myeloma precursor cells.The variable parts of the immunoglobulin heavy chains linked to either Calpha or Cepsilon were exactly the same, including the same somatic mutations. From the in vitro CD40 cultures B cells could be isolated that either expressed IgA or IgE with exactly the same variable immunoglobulin part as the myeloma clone. No pre-switched IgM myeloma-related B cells could be found.Both cell populations in this IgA/IgE myeloma patient shared a common clonal origin. No evidence for a pre-switched IgM precursor myeloma cell was found in this patient.

Follicular lymphoma (FL) cells have inherited an activated hypermutation mechanism from their origin of germinal centre B cells. Based on today's knowledge of the intrinsic properties related to this mechanism and the VH base composition, reconsideration of previous reports should be made on a broader range of samples. The present study examined the mutation pattern of the VH genes expressed by 55 cases of FL. FL VH genes showed evidence of antigenic selection in 30% of cases with 88% carrying a functional sIg and 78.2% showing intraclonal variation. VH family and gene segment utilization was found to be roughly similar to that of normal B lymphocytes. FL VH genes revealed extensive variations. 17% of the VH exons harboured a total of five deletions, three duplications and two insertions as compared to the most homologous germline counterpart. The VH genes of one tumour displayed three populations with varying CDR3 length at diagnosis. At relapse, emergence of a differently mutated gene, additional mutations reminiscent of ongoing mutations or no variation was prominent. From this study the heterogeneity of FLs is well established and ongoing mutations are seen in the scope of the activated status of the hypermutation mechanism rather than antigen-stimulated tumour growth.

Fas is a protein that plays a major role in the apoptotic mechanism of several cell types, including white blood cells (WBC). Mutations of the Fas gene in humans are known to lead to autoimmune lymphoproliferative syndrome (ALPS). Glucocorticoids or cytostatic drugs are sometimes used to treat the lymphoproliferation in these patients. When treated with the anti-malaria drug Fansidar®, a patient with ALPS showed a marked shrinkage of the lymph node masses, decrease in peripheral blood lymphocytes (PBL) and an increase in neutrophil numbers. In addition, an increased Fas expression was seen on all types of leucocytes.

The presence of ETV6 deletions was investigated in 215 children with acute lymphoblastic leukemia (ALL) using the loss of heterozygosity (LOH) approach. We used four intragenic or juxtagenic microsatellite markers to detect allelic deletions. In this series of unselected patients, LOH of ETV6 markers was found in 23% of cases (6% of T-ALL and 26% of B lineage ALL) confirming that chromosome 12p12-13 deletions represent a major genetic alteration in childhood ALL, frequently missed by cytogenetic analysis. The presence of a t(12;21)(p13;q22) was studied by RT-PCR and/or FISH in a total of 134 patients (125 B lineage ALL, nine T-ALL) including 42 cases with LOH. Thirty-four out of 44 patients (77%) for whom a t(12;21) was observed displayed LOH of the ETV6 markers. When associated with a t(12;21), ETV6 is very likely to be the target of deletions as indicated by the detection of intragenic deletions in three patients. Although deletion of ETV6 and t(12;21) were associated in most patients, in eight cases (six B lineage and two T-ALL) LOH was detected at the ETV6 locus without ETV6-AML1 hybrid RNA. FISH studies conducted in five of these eight patients confirmed the absence of translocation involving ETV6. In such patients, the other allele of ETV6 could be disrupted by either a small deletion, a point mutation, or an epigenetic modification and it will be of interest to study the structure and expression of the remaining allele of ETV6 in these cases. Alternatively, a tumor suppressor gene located close to ETV6 and CDKN1B could be the target of deletions.

Multiple myeloma (MM) is a B-cell malignancy characterized by the expansion of malignant plasma cells within the bone marrow. Previous studies that have examined the Ig VH genes of IgG and IgA MMs have shown the presence of somatic mutations, suggesting that in these cases, the myeloma precursor cell passed through the phase of antigenic selection within the germinal center but is no longer exposed to the somatic mutation process. However, no information about this matter is available in the rare IgD and IgM MM variants. Therefore, we have analyzed the Ig VH genes of three IgD, one IgM, and one biclonal (IgG and IgM) MM for the presence of somatic mutations. Our study demonstrates that all of these myeloma clones have accumulated a high number of somatic mutations within their Ig VH genes but show no intraclonal variation. Moreover, proof that the clone sustained a strong antigenic selection pressure could be provided in three cases (one IgD and two IgMs). Therefore, this study strongly implies that IgD and IgM MMs emerge from a postgerminal center preswitched B cell that is no longer exposed to the somatic mutation process or able to undergo further isotype switching in vivo.

The importance of minimal residual disease detection has increased due to the advanced therapeutic protocols available for multiple myeloma and acute leukaemia. High-dose chemotherapy, followed by stem cell transplantation is often used in patients with multiple myeloma. But despite a longer disease-free period and overall survival, all patients relapse. In the treatment of acute leukaemia, there are similar problems. The present strategy is to give continuous chemotherapy to eradicate minimal residual disease. In this review, we consider the methods used to detect and quantify minimal residual disease. At present, the most effective seem to be those based on the use of polymerase chain reactions to detect the malignant cells.

Abstract 121 The genetic landscape of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in children above 10 years and adolescents remains poorly defined. Specifically, more than half of these patients have none of the cytogenetic abnormalities that define oncogenic subtypes and underlie risk stratification. To uncover new genetic abnormalities in these unassigned cases, we studied 85 BCP-ALL from patients aged 10 to 17 diagnosed at St-Louis hospital (Paris, France), for which the main classifying genetic lesions were assessed (i.e. high hyperdiploidy, t(12;21)/ETV6-RUNX1, t(1;19)/TCF3-PBX1, t(9;22)/BCR-ABL1, iAMP21, MLL translocations, low hypodiploidy, and near haploidy). Fifty of these BCP-ALL presented no classifying genetic lesions. Paired leukemic and remission samples could be analysed by high density array-CGH (Agilent 1M arrays) in 17 of these unassigned cases. We focused on acquired, focal, and recurrent copy-number abnormalities. A mono-allelic intragenic deletion of the ETS-related Gene (ERG) was found in 3 cases. ERG belongs to the ETS family of transcription factors and is implicated in chromosomal translocations associated with several cancer types including acute myeloid leukemia. The possibility of a cryptic unbalanced translocation was ruled out in the 3 cases by FISH analysis. The deletions encompassed exons 3 to 7, or 3 to 9, and the breakpoints were tightly clustered. Based on the breakpoint sequences we designed a PCR assay that allowed us to screen ERG intragenic deletions in the whole cohort. ERG deletion was identified in 9 additional cases, none of them having any of the known classifying genetic lesions, bringing up to 25% (12 out of 50) the frequency of ERG deletion in unassigned BCP-ALL of children older than 10. These results suggested that ERG deletion characterized a novel oncogenic subtype of BCP-ALL. Of note, these results were consistent with independent data of Harvey et al. (2010) that reported ERG deletions in a distinct gene-expression cluster. To confirm and extend these findings in the whole population of paediatric BCP-ALL, we used our breakpoint-specific PCR assay to screen ERG deletions in an independent cohort of 822 unselected patients aged 1 to 17, enrolled in the EORTC 58951 trial. ERG deletion was identified in 31/822 (3.7%) patients. Again, none of them had another known classifying genetic lesion, confirming that ERG deletion characterizes a distinct oncogenic subtype. Patients with ERG deletion were significantly older compared to other patients (median 7.0 vs 4.0, p=0.002), but they had similar white blood counts at diagnosis. They had a favourable outcome, with a 8-year event free survival (EFS) of 82.4% and overall survival (OS) of 96.0%, which is similar to EFS of 83.4% and OS of 91.6% obtained for patients having no very high risk initial features (i.e. no t(9;22)/BCR-ABL1, MLL rearrangement or haploidy/low hypodiploidy). IKZF1 deletion is a cooperative genetic lesion that has been recently shown to be associated with a poor outcome in BCP-ALL. Remarkably, the incidence of IKZF1 deletions in patients with ERG deletion was significantly higher than in other BCR-ABL1-negative patients, especially when considering the IKZF1 intragenic deletion Δ4-7 (10/31, 32.3% vs 34/744, 4.6%, P Altogether, we have identified a novel oncogenic subtype of BCP-ALL characterized by ERG deletion. This subtype is frequently associated with IKZF1 deletions, suggesting a preferred oncogenic cooperation. Importantly, despite having older age and frequent IKZF1 deletions, which are factors usually predictive of a poor prognosis, patients with ERG deletion have a favourable outcome. Therefore, this genetic abnormality may be systematically assessed as part of the diagnostic work-up of BCP-ALL and taken into account when considering treatment stratification. Disclosures: No relevant conflicts of interest to declare.

Abstract 2742 Molecular monitoring of BCR/ABL transcripts by real time quantitative reverse transcription PCR (qRT-PCR) is an essential technique for clinical management of patients with BCR/ABL-positive CML and ALL. Though quantitative BCR/ABL assays are performed in hundreds of laboratories worldwide, results among these laboratories cannot be reliably compared due to heterogeneity in test methods, data analysis, reporting, and lack of quantitative standards. Recent efforts towards standardization have been limited in scope. Aliquots of RNA were sent to clinical test centers worldwide in order to evaluate methods and reporting for e1a2, b2a2, and b3a2 transcript levels using their own qRT-PCR assays. Total RNA was isolated from tissue culture cells that expressed each of the different BCR/ABL transcripts. Serial log dilutions were prepared, ranging from 100 to 10−5, in RNA isolated from HL60 cells. Laboratories performed 5 independent qRT-PCR reactions for each sample type at each dilution. In addition, 15 qRT-PCR reactions of the 10−3 b3a2 RNA dilution were run to assess reproducibility within and between laboratories. Participants were asked to run the samples following their standard protocols and to report cycle threshold (Ct), quantitative values for BCR/ABL and housekeeping genes, and ratios of BCR/ABL to housekeeping genes for each sample RNA. Thirty-seven (n=37) participants have submitted qRT-PCR results for analysis (36, 37, and 34 labs generated data for b2a2, b3a2, and e1a2, respectively). The limit of detection for this study was defined as the lowest dilution that a Ct value could be detected for all 5 replicates. For b2a2, 15, 16, 4, and 1 lab(s) showed a limit of detection at the 10−5, 10−4, 10−3, and 10−2 dilutions, respectively. For b3a2, 20, 13, and 4 labs showed a limit of detection at the 10−5, 10−4, and 10−3 dilutions, respectively. For e1a2, 10, 21, 2, and 1 lab(s) showed a limit of detection at the 10−5, 10-4, 10-3, and 10-2 dilutions, respectively. Log %BCR/ABL ratio values provided a method for comparing results between the different laboratories for each BCR/ABL dilution series. Linear regression analysis revealed concordance among the majority of participant data over the 10-1 to 10-4 dilutions. The overall slope values showed comparable results among the majority of b2a2 (mean=0.939; median=0.9627; range (0.399 – 1.1872)), b3a2 (mean=0.925; median=0.922; range (0.625 – 1.140)), and e1a2 (mean=0.897; median=0.909; range (0.5174 – 1.138)) laboratory results (Fig. 1–3)). Thirty-four (n=34) out of the 37 laboratories reported Ct values for all 15 replicates and only those with a complete data set were included in the inter-lab calculations. Eleven laboratories either did not report their copy number data or used other reporting units such as nanograms or cell numbers; therefore, only 26 laboratories were included in the overall analysis of copy numbers. The median copy number was 348.4, with a range from 15.6 to 547,000 copies (approximately a 4.5 log difference); the median intra-lab %CV was 19.2% with a range from 4.2% to 82.6%. While our international performance evaluation using serially diluted RNA samples has reinforced the fact that heterogeneity exists among clinical laboratories, it has also demonstrated that performance within a laboratory is overall very consistent. Accordingly, the availability of defined BCR/ABL RNAs may facilitate the validation of all phases of quantitative BCR/ABL analysis and may be extremely useful as a tool for monitoring assay performance. Ongoing analyses of these materials, along with the development of additional control materials, may solidify consensus around their application in routine laboratory testing and possible integration in worldwide efforts to standardize quantitative BCR/ABL testing. Download : Download high-res image (127KB) Download : Download full-size image Download : Download high-res image (127KB) Download : Download full-size image Download : Download high-res image (128KB) Download : Download full-size image Disclosure: Sher: Invivoscribe Technologies Inc: Employment. Miller: Invivoscribe Technologies Inc: Employment. Huang: Invivoscribe Technologies Inc: Employment. Shaw: Invivoscribe Technologies Inc: Employment.

To investigate whether somatic hypermutation occurs in multiple myeloma (MM) Ig VH region genes, we have cloned and sequenced the expressed VH genes from five cases of MM. The sequences were obtained after polymerase chain reaction (PCR) on total RNA isolated from the bone marrow, using 5′ VH family-specific leader and 3′ C gamma- or C alpha- specific primers. MM-specific CDR3 oligonucleotides were produced to isolate VH genes expressed by the malignant plasma cells. In all five cases, the productive Ig gene used the VH3 family. Extensive sequence analysis of multiple independent M13 clones showed no intraclonal variation with no evidence for ongoing somatic hypermutation in MM VH region genes. We were able to identify possible germline counterparts of the expressed VH genes in two cases. Comparison of these genes shows that the MM VH region genes have somatic mutations characteristic for an antigen-driven process. In the other three cases, no close homology could be found with published VH3 sequences. These findings implicate that, in MM, clonal proliferation takes place in a cell type that has already passed through the phase of somatic hypermutation.

CD34+ selection of peripheral blood progenitor cells (PBPC) was used in Multiple Myeloma (MM) in an attempt to reduce tumor cell contamination and relapse rate. From May 1995 to November 1999, 127 patients from 17 EBMT centers with newly diagnosed advanced MM were entered into a phase III trial. Responders to 3 cycles of VAD were randomized to receive either CD34+ selected (arm A) or unselected PBPC (arm B) following myeloablative conditioning treatment. PBPC were harvested following mobilization with cyclophosphamide 4g/m² and G-CSF (Filgrastim, AMGEN, Europe). Conditioning regimen in both arms was TBI and high dose melphalan 140 mg/m². CD34+ cell selection was performed in arm A using the CellPro Ceprate-SC device. The analysis concerns the 111 patients who were transplanted (56 arm A and 55 arm B). The median follow-up at the time of the analysis was 65 months. CD34+ selection resulted in a median purity of 87% and a yield of 50%. Molecular analysis showed a median tumor cell depletion of 2.0 log (range 0.3–85.5). The median number of CD34+ cells reinfused/kg was 5.8 x 106 (1.42–50.4) in arm A and 7.4x106 (1.85–99.2) in arm B. The median time to neutrophil engraftment (ANC >0.5x109/l) was 10 days (range 8–14) in arm A and 10 days (range 8–21) in arm B. The median time to platelet engraftment (plts>20 x 109/l) was 11 days (range 5–26) in arm A and 9 days (range 5–42) in arm B (p=0.005). One patient died before platelets engraftment in arm A. Twelve patients experienced at least one episode of serious infection (total episodes =17) before day 100 in arm A compared to 3 patients (total episodes = 6) in arm B (p=0.02). For 3 patients in arm A, these infections were fatal (including the patient who died before time to platelet engraftment). There was no significant difference in CR rate at 1 year as defined by EBMT/IBMTR/ABMTR criteria (27% in arm A and 20% in arm B). The 5 year overall survival (OS) was 51% in arm A and 45% in arm B (p=0.80). The 5 year event free survival was 20% in arm A and 18% in arm B (p=0.45). The increased incidence of severe infections in the CD34+ selected arm in the early post transplant may be due to impaired immune reconstitution. Thus, no long term clinical benefit is obtained by CD34+ selection despite significant tumor cell reduction.

Abstract 2571 Background: In our previous EORTC 58881 trial in childhood ALL, we have shown the prognostic impact of the MRD, quantitated by polymerase chain reaction assay. Patients with TP1 MRD ≥10–2 (D35), had a higher risk of relapse than those with TP1 MRD Methods: Between December 1998 and July 2008, 1955 children (1y-18y) with ALL were enrolled in the 58951 trial, 1459 being evaluable for the MRD (TP1) by PCR (rearrangements of the T-cell receptor and immunoglobulin heavy chain genes). Seventy-nine patients with Phi-negative ALL had a TP1 MRD ≥10-2, and 69 of them achieved a complete hematological remission after induction. Here we report on the outcome of these 69 patients. Results: At a median follow-up of 7.6 years, the overall 5-years EFS and OS rates for the 69 patients were 56.1% (SE 6.0%) and 62.0% (SE 5.9%) respectively. Prephase good responders (PGR) ( 51 chromosomes were PGR. TP2 MRD (after consolidation) was assessed in 59 pts. All patients but one (1/13) with TP2 MRD ≥10-2 died. In PGR patients, those with TP2 MRD < 10-3 (N=18) had a significant better OS rate at 5 years than those with TP2 MRD ≥10-3 (N=17): 88.9% (SE 7.4%) vs 52.3 % (SE 12.3%), hazard ratio=0.17, p=0.009. We observed no relapses among patients with hyperdiploidy > 51 chromosomes and TP2 Conclusions: The prognosis of children ALL with TP1 MRD ≥10-2 has improved with early intensification of the treatment as compared to the one observed in our previous 58881 study. However the outcome of these patients was still heterogeneous and the prephase response was still of prognostic importance. Patients with GPR and TP2 For other patients with PPR and/or TP2 ≥10-3 the prognosis was worse and these patients may benefit from alternative therapy and/or intensification with HSCT. Disclosures: No relevant conflicts of interest to declare.