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Chronic lymphocytic leukemia (CLL) and the other low-grade non-Hodgkin lymphomas are among the most common lymphoid malignancies. Recent studies suggest that more than 4% of the general population over age 40 harbor a population of clonal B cells with the phenotype of either CLL or another B-cell malignancy, a condition now designated monoclonal B-cell lymphocytosis (MBL). Although all cases of CLL appear to be preceded by MBL, the majority of individuals with MBL will not develop a hematologic malignancy. The biologic characteristics and clinical implications of MBL appear to differ based on whether it is identified during the diagnostic evaluation of lymphocytosis or incidentally discovered through screening of individuals with normal lymphocyte counts as part of research studies using highly sensitive detection methods. In this paper, we provide a state of the art review on the prevalence, nomenclature, biology, natural history and clinical management of MBL. [ABSTRACT FROM AUTHOR]

Despite major improvements in allogeneic hematopoietic cell transplantation over the past decades, corticosteroid-refractory (SR) acute (a) and chronic (c) graft-versus-host disease (GVHD) cause high mortality. Preclinical evidence indicates the potent anti-inflammatory properties of the JAK1/2 inhibitor ruxolitinib. In this retrospective survey, 19 stem cell transplant centers in Europe and the United States reported outcome data from 95 patients who had received ruxolitinib as salvage therapy for SR-GVHD. Patients were classified as having SR-aGVHD (n=54, all grades III or IV) or SR-cGVHD (n=41, all moderate or severe). The median number of previous GVHD-therapies was 3 for both SR-aGVHD (1-7) and SR-cGVHD (1-10). The overall response rate was 81.5% (44/54) in SR-aGVHD including 25 complete responses (46.3%), while for SR-cGVHD the ORR was 85.4% (35/41). Of those patients responding to ruxolitinib, the rate of GVHD-relapse was 6.8% (3/44) and 5.7% (2/35) for SR-aGVHD and SR-cGVHD, respectively. The 6-month-survival was 79% (67.3-90.7%, 95% confidence interval (CI)) and 97.4% (92.3-100%, 95% CI) for SR-aGVHD and SR-cGVHD, respectively. Cytopenia and cytomegalovirus-reactivation were observed during ruxolitinib treatment in both SR-aGVHD (30/54, 55.6% and 18/54, 33.3%) and SR-cGVHD (7/41, 17.1% and 6/41, 14.6%) patients. Ruxolitinib may constitute a promising new treatment option for SR-aGVHD and SR-cGVHD that should be validated in a prospective trial. [ABSTRACT FROM AUTHOR]

Severe combined immunodeficiency (SCID) patients with an inactivating mutation in recombination activation gene 1 (RAG1) lack B and T cells due to the inability to rearrange immunoglobulin (Ig) and T-cell receptor (TCR) genes. Gene therapy is a valid treatment option for RAG-SCID patients, especially for patients lacking a suitable bone marrow donor, but developing such therapy has proven challenging. As a preclinical model for RAG-SCID, we used Rag1-/- mice and lentiviral self-inactivating (SIN) vectors harboring different internal elements to deliver native or codon-optimized human RAG1 sequences. Treatment resulted in the appearance of B and T cells in peripheral blood and developing B and T cells were detected in central lymphoid organs. Serum Ig levels and Ig and TCR Vβ gene segment usage was comparable to wild-type (WT) controls, indicating that RAG-mediated rearrangement took place. Remarkably, relatively low frequencies of B cells produced WT levels of serum immunoglobulins. Upon stimulation of the TCR, corrected spleen cells proliferated and produced cytokines. In vivo challenge resulted in production of antigen-specific antibodies. No leukemia development as consequence of insertional mutagenesis was observed. The functional reconstitution of the B- as well as the T-cell compartment provides proof-of-principle for therapeutic RAG1 gene transfer in Rag1-/- mice using lentiviral SIN vectors. [ABSTRACT FROM AUTHOR]

Dysregulation of the Wnt/β-catenin pathway has been observed in various malignancies, including acute myeloid leukemia (AML), where the overexpression of β-catenin is an independent adverse prognostic factor. β-catenin was found upregulated in the vast majority of AML samples and more frequently localized in the nucleus of leukemic stem cells compared with normal bone marrow CD34(+) cells. The knockdown of β-catenin, using a short hairpin RNA (shRNA) lentiviral approach, accelerates all-trans retinoic acid-induced differentiation and impairs the proliferation of HL60 leukemic cell line. Using in vivo quantitative tracking of these cells, we observed a reduced engraftment potential after xenotransplantation when β-catenin was silenced. However, when studying primary AML cells, despite effective downregulation of β-catenin we did not observe any impairment of their in vitro long-term maintenance on MS-5 stroma nor of their engraftment potential in vivo. Altogether, these results show that despite a frequent β-catenin upregulation in AML, leukemia-initiating cells might not be 'addicted' to this pathway and thus targeted therapy against β-catenin might not be successful in all patients. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented that focuses on a study on the frequency and impact of the histone methyltransferase (EZH2) mutations on follicular lymphoma (FL) patients.

Historically, genes targeted by recurrent chromosomal deletions have been identified within the smallest genomic region shared in all patients, the minimally deleted region (MDR). However, deletions this small do not occur in all patients and are a simplification of the impact larger heterogeneous deletions have during carcinogenesis. We use the example of 13q14 deletions in chronic lymphocytic leukemia to show that genes outside MDRs are associated with disease progression. Genomic profiling of 224 patients identified 205 copy number alterations on chromosome 13 in 132 cases. Deletions including DLEU2 were heterogeneous (845 Kb-96.2 Mb) and identified two breakpoint cluster regions within short interspersed nuclear elements proximal to DLEU2 and within long interspersed nuclear elements/L1 repeats distal to GUCY1B2. After defining a deletion class on the basis of size and location, we show that (a) at diagnosis, larger deletions (class II) were associated with a significantly increased risk of disease progression (odds ratio=12.3; P=0.005), (b) in progressive patients, class II deletions were enriched (P=0.02) and (c) this association was independent of IgVH mutational status, ZAP70 expression and ATM/TP53 deletion. Deletion of a 1 Mb gene cluster (48.2-49.2 Mb), including SETDB2, PHF11 and RCBTB1, was significantly associated (P<0.01) with disease progression. Here, we show that the deletion of genes outside MDRs can influence clinical outcome. [ABSTRACT FROM AUTHOR]

Despite the success of imatinib mesylate (IM) in the early chronic phase of chronic myeloid leukemia (CML), patients are resistant to IM and other kinase inhibitors in the later stages of CML. Our findings indicate that inhibition of Janus kinase 2 (Jak2) in Bcr-Abl+ cells overcomes IM resistance although the precise mechanism of Jak2 action is unknown. Knocking down Jak2 in Bcr-Abl+ cells reduced levels of the Bcr-Abl protein and also the phosphorylation of Tyr177 of Bcr-Abl, and Jak2 overexpression rescued these knockdown effects. Treatment of Bcr-Abl+ cells with Jak2 inhibitors for 4-6 h but not with IM also reduced Bcr-Abl protein and pTyr177 levels. In vitro kinase experiments performed with recombinant Jak2 showed that Jak2 readily phosphorylated Tyr177 of Bcr-Abl (a Jak2 consensus site, YvnV) whereas c-Abl did not. Importantly, Jak2 inhibition decreased pTyr177 Bcr-Abl in immune complexes but did not reduce levels of Bcr-Abl, suggesting that the reduction of Bcr-Abl by Jak2 inhibition is a separate event from phosphorylation of Tyr177. Jak2 inhibition by chemical inhibitors (TG101209/WP1193) and Jak2 knockdown diminished the activation of Ras, PI-3 kinase pathways and reduced levels of pTyrSTAT5. These findings suggest that Bcr-Abl stability and oncogenic signaling in CML cells are under the control of Jak2. [ABSTRACT FROM AUTHOR]

This cooperative study assessed prognostic factors for overall survival (OS) and risk of transformation to acute myeloid leukemia (AML) in 541 patients with de novo myelodysplastic syndrome (MDS) and deletion 5q. Additional chromosomal abnormalities were strongly related to different patients' characteristics. In multivariate analysis, the most important predictors of both OS and AML transformation risk were number of chromosomal abnormalities (P<0.001 for both outcomes), platelet count (P<0.001 and P=0.001, respectively) and proportion of bone marrow blasts (P<0.001 and P=0.016, respectively). The number of chromosomal abnormalities defined three risk categories for AML transformation (del(5q), del(5q)+1 and del(5q)+ ≥ 2 abnormalities) and two for OS (one group: del(5q) and del(5q)+1; and del(5q)+ ≥ 2 abnormalities, as the other one); with a median survival time of 58.0 and 6.8 months, respectively. Platelet count (P=0.001) and age (P=0.034) predicted OS in patients with '5q-syndrome'. This study demonstrates the importance of additional chromosomal abnormalities in MDS patients with deletion 5q, challenges the current '5q-syndrome' definition and constitutes a useful reference series to properly analyze the results of clinical trials in these patients. [ABSTRACT FROM AUTHOR]

Ligation of CD40 on chronic lymphocytic leukemia (CLL) cells induces phenotypic and biochemical changes that facilitate CLL cell-T cell interactions and enhances the sensitivity of CLL cells to clearance by adaptive and innate immune-effector mechanisms. CLL cells can be transduced to express CD40 ligand (CD154) using a replication-defective adenovirus vector, thereby cross-linking CD40 on transduced and non-transduced, bystander CLL cells. In a previous study, patients received infusions of autologous CLL cells, transduced to express murine CD154 (mCD154), which induced anti-leukemic immune responses, but also anti-mCD154 antibodies. In this study, we report a phase I study, in which patients were infused with 1 × 10(8), 3 × 10(8) or 1 × 10(9) autologous CLL cells transduced ex vivo to express ISF35, a humanized, membrane-stable CD154. Infusions were well tolerated and consistently followed by reductions in blood lymphocyte counts and lymphadenopathy. After infusion, circulating CLL cells had enhanced or de novo expression of CD95, DR5, p73 and Bid, which enhanced their susceptibility to death-receptor-mediated or drug-induced apoptosis, including CLL cells with deletions at 17p13.1 (del(17p)). Two patients who had CLL with del(17p) had subsequent chemoimmunotherapy and responded well to treatment. In summary, infusions of autologous, ISF35-transduced CLL cells were well tolerated, had biological and clinical activity, and might enhance the susceptibility of CLL cells with del(17p) to chemoimmunotherapy. [ABSTRACT FROM AUTHOR]

The article presents a study to examine the effect of physiological hypoxia in leukemia cells. It observes that the functional consequences of mitogen-activated protein kinases (MAPK) activation on acute myeloid leukemia cells (AML) adjusted to hypoxic conditions. It concludes that the physiological hypoxia helps in promoting lipid raft and PI3K-regulated mechanism of MAPK 42/44 in leukemia cells.

A letter to the editor is presented related to non-Hodgkin lymphoma.

The transcription factor CCAAT enhancer-binding protein alpha (C/EBPalpha) has an important role in granulopoiesis. The tumor suppressor function of C/EBPalpha is shown by the findings that loss of expression or function of C/EBPalpha in leukemic blasts contributes to a block in myeloid cell differentiation and to leukemia. C/EBPalpha mutations are found in around 9% of acute myeloid leukemia (AML) patients. The mechanism by which the mutant form of C/EBPalpha (C/EBPalpha-p30) exerts a differentiation block is not well understood. By using a proteomic screen, we have recently reported PIN1 as a target of C/EBPalpha-p30 in AML. In the present study, we show that C/EBPalpha-p30 induces PIN1 expression. We observed elevated PIN1 expression in leukemic patient samples. Induction of C/EBPalpha-p30 results in recruitment of E2F1 in the PIN1 promoter. We show that the inhibition of PIN1 leads to myeloid differentiation in primary AML blasts with C/EBPalpha mutations. Overexpression of PIN1 in myeloid cells leads to block of granulocyte differentiation. We also show that PIN1 increases the stability of the c-Jun protein by inhibiting c-Jun ubiquitination, and c-Jun blocks granulocyte differentiation mediated by C/EBPalpha. Our data suggest that the inhibition of PIN1 could be a potential strategy of treating AML patients with C/EBPalpha mutation. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented that examines the impact of inhibition of Syk protein tyrosine kinase in T-cell non-Hodgkin's lymphoma cell lines.

Xenotransplantation of human acute myeloid leukemia (AML) in immunocompromised animals has been critical for defining leukemic stem cells. However, existing immunodeficient strains of mice have short life spans and low levels of AML cell engraftment, hindering long-term evaluation of primary human AML biology. A recent study suggested that NOD/LtSz-scid IL2Rgammac null (NSG) mice have enhanced AML cell engraftment, but this relied on technically challenging neonatal injections. Here, we performed extensive analysis of AML engraftment in adult NSG mice using tail vein injection. Of the 35 AML samples analyzed, 66% showed bone marrow engraftment over 0.1%. Further, 37% showed high levels of engraftment (>10%), with some as high as 95%. A 2-44-fold expansion of AML cells was often seen. Secondary and tertiary recipients showed consistent engraftment, with most showing further AML cell expansion. Engraftment did not correlate with French-American-British subtype or cytogenetic abnormalities. However, samples with FLT3 mutations showed a higher probability of engraftment than FLT3 wild type. Importantly, animals developed organomegaly and a wasting illness consistent with advanced leukemia. We conclude that the NSG xenotransplantation model is a robust model for human AML cell engraftment, which will allow better characterization of AML biology and testing of new therapies. [ABSTRACT FROM AUTHOR]

The consensus views of an expert roundtable meeting are presented as updated management guidelines for using alemtuzumab in chronic lymphocytic leukemia. Since the publication of previous management guidelines in 2004, clinical experience with alemtuzumab has grown significantly, especially regarding its efficacy and safety, management of cytomegalovirus (CMV) reactivation, identification of patient subgroups likely to benefit from alemtuzumab therapy and subcutaneous administration of alemtuzumab. The updated recommendations include (1) alemtuzumab monotherapy can be safely used as first-line therapy; (2) suitable patient subgroups for alemtuzumab therapy include elderly patients, patients with 17p deletion, patients with refractory autoimmune cytopenias and patients with profound pancytopenia at baseline due to heavily infiltrated bone marrow; (3) alemtuzumab treatment should be continued for 12 weeks (36 doses) whenever possible, and bone marrow examination may be considered at week 12 to evaluate response; (4) monitoring CMV reactivation by weekly PCR is mandated during therapy; when CMV reactivation becomes symptomatic or viremia increases, alemtuzumab therapy should be interrupted and anti-CMV therapy started; (5) subcutaneous administration is safe, easy to perform and appears equally effective compared with intravenous infusion and (6) our strong recommendation is that alemtuzumab combination therapy and consolidation therapy shall not be used outside carefully controlled clinical studies. [ABSTRACT FROM AUTHOR]

Imatinib mesylate and nilotinib are highly effective at eradicating the majority of chronic myeloid leukemia (CML) cells; however, neither agent induces apoptosis of primitive CML CD34(+) cells. One possible explanation is that CD34(+) cells do not accumulate sufficient intracellular drug levels because of either inadequate active uptake or increased efflux. To determine the interaction of nilotinib with major clinically implicated drug transporters, we analyzed their interactions with MDR1 (ABCB1), MRP1 (ABCC1), ABCG2 (BCRP) and human organic cation transporter (hOCT)1 in CML cell lines and primitive (CD34(+)) primary CML cells. Nilotinib is neither dependent on active import by hOCT1, nor effluxed through the ATP-binding cassette transporters analyzed. Indeed, we found nilotinib to be an inhibitor of hOCT1, MDR1 and ABCG2. The efflux transporters MDR1, MRP1 and ABCG2 are expressed on CML CD34(+) cells at 13.5, 108 and 291% of control, respectively, although hOCT1 expression was absent; however, inhibition of efflux transporter activity did not potentiate the effect of nilotinib on apoptosis, Bcr-Abl inhibition or CML CD34(+) cell proliferation. Therefore, we have found no evidence for either active uptake of nilotinib through hOCT1 or efflux through MDR1, MRP1 or ABCG2, and it is therefore unlikely that these transporters will have any effect on the clinical response to this drug. [ABSTRACT FROM AUTHOR]

Kinesin spindle protein (KSP), a microtubule-associated motor protein essential for cell cycle progression, is overexpressed in many cancers and is a potential anti-tumor target. We found that inhibition of KSP by a selective inhibitor, ARRY-520, blocked cell cycle progression, leading to apoptosis in acute myeloid leukemia cell lines that express high levels of KSP. Knockdown of p53, overexpression of XIAP and mutation in caspase-8 did not significantly affect sensitivity to ARRY-520, suggesting that the response is independent of p53, XIAP and the extrinsic apoptotic pathway. Although ARRY-520 induced mitotic arrest in both HL-60 and Bcl-2-overexpressing HL-60Bcl-2 cells, cell death was blunted in HL-60Bcl-2 cells, suggesting that the apoptotic program is executed through the mitochondrial pathway. Accordingly, inhibition of Bcl-2 by ABT-737 was synergistic with ARRY-520 in HL-60Bcl-2 cells. Furthermore, ARRY-520 increased Bim protein levels prior to caspase activation in HL-60 cells. ARRY-520 significantly inhibited tumor growth of xenografts in SCID mice and inhibited AML blast but not normal colony formation, supporting a critical role for KSP in proliferation of leukemic progenitor cells. These results demonstrate that ARRY-520 potently induces cell cycle block and subsequent death in leukemic cells via the mitochondrial pathway and has the potential to eradicate AML progenitor cells. [ABSTRACT FROM AUTHOR]

Quantitative methylation profiling was performed using the Illumina GoldenGate Assay in untreated follicular lymphoma (FL) (164), paired pre- and post-transformation FL (20), benign haematopoietic (24) samples and purified B and T cells from two FL cases. Methylation values allowed separation of untreated FL samples from controls with one exception, based primarily on tumour-specific gains of methylation typically occurring within CpG islands. Genes that are targets for epigenetic repression in stem cells by Polycomb Repressor Complex 2 were significantly over-represented among hypermethylated genes. Methylation profiles were conserved in sequential FL and t-FL biopsies, suggesting that widespread methylation represents an early event in lymphomagenesis and may not contribute substantially to transformation. A significant (P<0.05) correlation between FL methylation values and reduced gene expression was shown for up to 28% of loci. Methylation changes occurred predominantly in B cells with variability in the amount of non-malignant tissue between samples preventing conclusive correlation with survival. This represents an important caveat in attributing prognostic relevance to methylation and future studies in cancer will optimally require purified tumour populations to address the impact of methylation on clinical outcome. [ABSTRACT FROM AUTHOR]

The international staging system (ISS) for multiple myeloma (MM) is a validated alternative to the Durie-Salmon staging system (DSS) for predicting survival at diagnosis. We compared these staging systems for predicting outcomes after upfront autologous stem cell transplantation by analyzing the outcomes of 729 patients between 1995 and 2002. With a median follow-up of 56 months, the univariate probabilities (95% CI) of non-relapse mortality (NRM), relapse, progression-free survival (PFS) and overall survival (OS) at 5 years were 7, 68, 25 and 52%, respectively. The median OS for stages I, II, III by DSS and ISS were 82, 68, 50 and 64, 68, 45 months, respectively. The concordance between the two staging systems was only 36%. Staging systems were formally compared using Cox models fit with DSS and ISS stages. The relative risks of PFS and OS were significantly different for stages I vs II and II vs III for DSS, but only for stages II vs III for ISS. Although both systems were predictive of PFS and OS, the DSS was superior in formal statistical comparison using Brier score. However, neither system was strongly predictive of outcomes, indicating the need for newer schemes incorporating other prognostic markers. [ABSTRACT FROM AUTHOR]

Natural killer (NK)-cell malignancies are among the most aggressive lymphoid neoplasms with very poor prognosis. We performed array comparative genomic hybridization analysis on a number of NK cell lines and primary tumors to gain better understanding of the pathogenesis and tumor biology of these malignancies. We also obtained transcriptional profiles of genes residing in these regions and compared them with normal and activated NK cells. Only 30-50% of the genes residing in the gained or deleted regions showed corresponding increased or decreased expression. However, many of the upregulated genes in regions of gain are functionally important for the proliferation and growth of the neoplastic population. Genes downregulated in regions of loss included many transcription factors or repressors, tumor suppressors or negative regulators of the cell cycle. The minimal common region of deletion in 6q21 included three known genes (PRDM1, ATG5 and AIM1) showing generally low expression. Mutations resulting in truncated PRDM1 and changes in conserved amino-acid sequences of AIM1 were detected. Highly methylated CpG islands 5' of PRDM1 and AIM1 correlated with low expression of the transcripts. Reversal of methylation by Decitabine induced expression of PRDM1 and cell death. In conclusion, we have shown a general tumor-promoting effect of genetic alterations and have identified PRDM1 as the most likely target gene in del6q21. ATG5, an essential gene for autophagy and AIM1, a gene implicated in melanoma, may also participate in the functional abnormalities. [ABSTRACT FROM AUTHOR]

The introduction of thalidomide, bortezomib and lenalidomide has dramatically changed the treatment paradigm of multiple myeloma (MM). In patients eligible for autologous stem cell transplant (ASCT), combinations including thalidomide/dexamethasone (Thal/Dex) or bortezomib/dexamethasone (Bort/Dex) or lenalidomide/dexamethasone (Rev/Dex) have been introduced as induction regimens in patients eligible for ASCT. New induction regimens have significantly increased complete response rate before and after ASCT with a positive impact on progression-free survival. Maintenance therapy with thalidomide, under investigation with lenalidomide, may further prolong remission duration. In patients not eligible for ASCT, randomized studies have shown that melphalan, prednisone, thalidomide (MPT) and melphalan, prednisone and bortezomib (MPV) are both superior to melphalan and prednisone (MP), and are now considered standard of care. Ongoing trials will soon assess if MP plus lenalidomide may be considered an attractive option. More complex regimens combining thalidomide or bortezomib or lenalidomide with cyclophosphamide or doxorubicin have been also tested. In small cohorts of patients bortezomib or lenalidomide may overcome the poor prognosis induced by deletion 13 or translocation t(4;14) or deletion 17p13. If these data will be confirmed, a cytogenetically risk-adapted strategy might become the most appropriate strategy. [ABSTRACT FROM AUTHOR]

Despite great progress in curing childhood acute lymphoblastic leukemia (ALL), survival after relapse remains poor. We analyzed survival after relapse among 9585 pediatric patients enrolled on Children's Oncology Group clinical trials between 1988 and 2002. A total of 1961 patients (20.5%) experienced relapse at any site. The primary end point was survival. Patients were subcategorized by the site of relapse and timing of relapse from initial diagnosis. Time to relapse remains the strongest predictor of survival. Patients experiencing early relapse less than 18 months from initial diagnosis had a particularly poor outcome with a 5-year survival estimate of 21.0+/-1.8%. Standard risk patients who relapsed had improved survival compared with their higher risk counterparts; differences in survival for the two risk groups was most pronounced for patients relapsing after 18 months. Adjusting for both time and relapse site, multivariate analysis showed that age (10+ years) and the presence of central nervous system disease at diagnosis, male gender, and T-cell disease were significant predictors of inferior post-relapse survival. It can be noted that there was no difference in survival rates for relapsed patients in earlier vs later era trials. New therapeutic strategies are urgently needed for children with relapsed ALL and efforts should focus on discovering the biological pathways that mediate drug resistance. [ABSTRACT FROM AUTHOR]

The article discusses the systematic assessment of the tyrosine kinase mutations in chronic lymphocytic leukemia (CLL). The author claims that tyrosine kinase mutations in CLL has found no evidence for activating mutations, including in the entire ZAP-70 coding region, and suggests that the rate of acquired somatic mutation in CLL is low. In addition, the frequency of previously undescribed polymorphisms is significant and mandates the use of matched germline DNA in human cancer screens.

We performed a genome-wide analysis of promoter associated CpG island methylation using methylated CpG island amplification (MCA) coupled to representational differential analysis (RDA) or a DNA promoter microarray in acute lymphoblastic leukemia (ALL). We identified 65 potential targets of methylation with the MCA/RDA approach, and 404 with the MCA/array. Thirty-six (77%) of the genes identified by MCA/RDA were shared by the MCA/array approach. Chromosomal location of these genes was evenly distributed in all autosomes. Functionally, 303 of these genes clustered in 18 molecular pathways. Of the 36 shared genes, 31 were validated and 26 were confirmed as being hypermethylated in leukemia cell lines. Expression analysis of eight of these genes was epigenetically modulated by hypomethylating agents and/or HDAC inhibitors in leukemia cell lines. Subsequently, DNA methylation of 15 of these genes (GIPC2, RSPO1, MAGI1, CAST1, ADCY5, HSPA4L, OCLN, EFNA5, MSX2, GFPT2, GNA14, SALL1, MYO5B, ZNF382 and MN1) was validated in primary ALL samples. Patients with methylation of multiple CpG islands had a worse overall survival. This is the largest published list of potential methylation target genes in human leukemia offering the possibility of performing rational unbiased methylation studies in ALL. [ABSTRACT FROM AUTHOR]

Amplification of the NUP214-ABL1 oncogene can be detected in patients with T cell acute lymphoblastic leukemia (T-ALL). We screened 29 patients with T cell malignancies for the expression of NUP214-ABL1 by reverse transcription-polymerase chain reaction (RT-PCR). NUP214-ABL1 was detected in three (10%) patients. These results were confirmed by fluorescence in situ hybridization techniques. We also studied the activity of imatinib, nilotinib and dasatinib against the human NUP214-ABL1-positive cell lines PEER and BE-13. All three tyrosine kinase inhibitors decreased the viability of PEER and BE-13 cells, but nilotinib and dasatinib had >1-log lower IC(50) values than imatinib (P<0.001). In contrast, the NUP214-ABL-negative T-ALL cell line Jurkat, was remarkably resistant to tyrosine kinase inhibition. The inhibition of cellular proliferation was associated with time-dependent induction of apoptosis and inhibition of ABL, CrKL and STAT5 phosphorylation. Moreover, dasatinib was active in a NUP214-ABL1-positive leukemia xenograft murine model and in marrow lymphoblasts from a patient with NUP214-ABL1-positive T-ALL. On the basis of these results, ABL1 kinase inhibitors warrant clinical investigation in patients with NUP214-ABL1-positive T-cell malignancies. [ABSTRACT FROM AUTHOR]

Plasma cell leukemia (PCL) is an aggressive and rare hematological malignancy that originates either as primary disease (pPCL) or as a secondary leukemic transformation (sPCL) of multiple myeloma (MM). We report here the genetic aberrations and survival of 80 patients with pPCL or sPCL and make comparisons with 439 cases of MM. pPCL presents a decade earlier than sPCL (54.7 vs 65.3 years) and is associated with longer median overall survival (11.1 vs 1.3 months; P<0.001). 14q32 (IgH) translocations are highly prevalent in both sPCL and pPCL (82-87%); in pPCL IgH translocations almost exclusively involve 11q13 (CCND1), supporting a central etiological role, while in sPCL multiple partner oncogenes are involved, including 11q13, 4p16 (FGFR3/MMSET) and 16q23 (MAF), recapitulating MM. Both show ubiquitous inactivation of TP53 (pPCL 56%; sPCL 83%) by coding mutation or 17p13 deletion; complemented by p14ARF epigenetic silencing in sPCL (29%). Both show frequent N-RAS or K-RAS mutation. Poor survival in pPCL was predicted by MYC translocation (P=0.006). Survival in sPCL was consistently short. Overall pPCL and sPCL are different disorders with distinct natural histories, genetics and survival. [ABSTRACT FROM AUTHOR]

Cytogenetic studies were performed as part of all diagnostic and surveillance bone marrow examinations in 956 newly diagnosed patients with multiple myeloma (MM) receiving total therapy (TT) protocols and in 1085 previously treated patients enrolled in non-TT protocols. In both groups, cytogenetic abnormalities (CA) were present in one-third at baseline and persisted in 14% prior to first and 10% prior to second transplant (TT, 5%; non-TT, 15%); post-transplant detection rates increased progressively with time, from 7% within 6 months to 21% within 24 months to 28% at relapse. According to multivariate analyses, overall survival was adversely affected by the presence of CA at baseline (hazard ratio (HR)=7.20, P<0.001) and the development of CA both prior to (HR=3.28, P<0.001) and after first transplant (HR=6.24, P<0.001), whereas suppression of CA pretransplant was favorable (HR=0.38, P<0.001). The presence of CA at relapse further distinguished patients with a short median post-relapse survival of only 11 versus 47 months in those without CA (P<0.0001). Post-relapse survival was independently adversely affected by the detection of CA both at baseline (HR=1.35, P=0.044) and relapse (HR=2.47, P<0.001). Collectively, these results underscore the importance of monitoring for CA and attest to the favorable prognostic consequences of CA suppression with effective therapy. [ABSTRACT FROM AUTHOR]

Mcl-1 is an antiapoptotic Bcl-2 family member, whose degradation is supposedly required for the induction of apoptosis. However, histone deacetylase inhibitors (HDACi) induce apoptosis primarily through the Bak/Mcl-1/Noxa and Bim pathways without decreasing Mcl-1. To investigate this discrepancy, we examined the role of Mcl-1 on HDACi-mediated apoptosis. Inhibition of either class I or class II HDAC by selective HDACi caused an upregulation of Mcl-1 mRNA and protein. Downregulation of Mcl-1 by three structurally unrelated cyclin-dependent kinase inhibitors potentiated HDACi-mediated apoptosis in primary chronic lymphocytic leukemic (CLL) cells and K562 cells. Sensitivity to HDACi-induced apoptosis was increased approximately 10-fold by the cyclin-dependent kinase inhibitors. Nanomolar concentrations of HDACi, approximately 300-fold lower than that required to induce apoptosis alone, sensitized cells to TRAIL, emphasizing that the mechanism(s) whereby HDACi induce apoptosis is clearly distinct from those by which they sensitize to TRAIL. Furthermore, knockdown of Mcl-1-potentiated HDACi-mediated apoptosis in K562 cells. Thus, HDACi-mediated Mcl-1 upregulation plays an important antiapoptotic regulatory role in limiting the efficacy of HDACi-induced apoptosis, which can be overcome by combination with an agent that downregulates Mcl-1. Thus, a clinical trial in some cancers is warranted using a combination of an HDACi with agents that downregulate Mcl-1. [ABSTRACT FROM AUTHOR]

Small molecule tyrosine kinase inhibitors, such as imatinib, are effective therapies for BCR-ABL-mediated human leukemias. However, clinical drug resistance occurs, which warrants development of alternative and/or complementary therapeutic strategies to target critical downstream signaling molecules. We recently demonstrated that disrupting 14-3-3/ligand association by a peptide-based 14-3-3 competitive antagonist R18 induces significant apoptosis, partially through reactivation of AKT-inhibited proapoptotic FOXO3a, in FGFR1 fusion-transformed hematopoietic cells. Here, we report that targeting 14-3-3 by R18 effectively induced significant apoptosis in Ba/F3 and K562 cells expressing BCR-ABL, similarly through liberation and reactivation of FOXO3a. Moreover, R18 sensitized BCR-ABL-transformed cells to inhibition with MEK1 inhibitor U0126, Bcl-2 inhibitor GX15-070, or mTOR inhibitor rapamycin. Treatment with these reagents potentiated R18-induced reactivation of proapoptotic FOXO3a with enhanced expression of downstream transcription targets p27(kip1) and Bim1. Furthermore, R18-induced apoptotic cell death in cells expressing diverse imatinib-resistant BCR-ABL mutants, including T315I. This inhibition was enhanced by R18 in combination with U0126 and rapamycin. Thus, our findings suggest that targeting 14-3-3 may potentiate the effects of conventional therapy for BCR-ABL-associated hematopoietic malignancies, and overcome drug resistance. [ABSTRACT FROM AUTHOR]

To characterize the molecular origin of primary lymphomas of the central nervous system (PCNSL), 21 PCNSLs of immunocompetent patients were investigated by microarray-based gene expression profiling. Comparison of the transcriptional profile of PCNSL with various normal and neoplastic B-cell subsets demonstrated PCNSL (i) to display gene expression patterns most closely related to late germinal center B cells, (ii) to display a gene expression profile similar to systemic diffuse large B-cell lymphomas (DLBCLs) and (iii) to be in part assigned to the activated B-cell-like (ABC) or the germinal center B-cell-like (GCB) subtype of DLBCL. [ABSTRACT FROM AUTHOR]

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed biologically and prognostically distinct subgroups: germinal center B-cell-like (GCB), activated B-cell-like (ABC) and primary mediastinal (PM) DLBCL. The BCL6 gene is often translocated and/or mutated in DLBCL. Therefore, we examined the BCL6 molecular alterations in these DLBCL subgroups, and their impact on BCL6 expression and BCL6 target gene repression. BCL6 translocations at the major breakpoint region (MBR) were detected in 25 (18.8%) of 133 DLBCL cases, with a higher frequency in the PM (33%) and ABC (24%) subgroups than in the GCB (10%) subgroup. Translocations at the alternative breakpoint region (ABR) were detected in five (6.4%) of 78 DLBCL cases, with three cases in ABC and one case each in the GCB and the unclassifiable subgroups. The translocated cases involved IgH and non-IgH partners in about equal frequency and were not associated with different levels of BCL6 mRNA and protein expression. BCL6 mutations were detected in 61% of DLBCL cases, with a significantly higher frequency in the GCB and PM subgroups (>70%) than in the ABC subgroup (44%). Exon-1 mutations were mostly observed in the GCB subgroup. The repression of known BCL6 target genes correlated with the level of BCL6 mRNA and protein expression in GCB and ABC subgroups but not with BCL6 translocation and intronic mutations. No clear inverse correlation between BCL6 expression and p53 expression was observed. Patients with higher BCL6 mRNA or protein expression had a significantly better overall survival. The biological role of BCL6 in translocated cases where repression of known target genes is not demonstrated is intriguing and warrants further investigation. [ABSTRACT FROM AUTHOR]

The majority of chronic phase chronic myeloid leukemia (CML) patients treated with the tyrosine kinase inhibitor (TKI) imatinib mesylate maintain durable responses to the drug. However, most patients relapse after withdrawal of imatinib and advanced stage patients often develop drug resistance. As CML is considered a hematopoietic stem cell cancer, it has been postulated that inherent protective mechanisms lead to relapse in patients. The ATP binding-cassette transporters ABCB1 (MDR-1; P-glycoprotein) and ABCG2 are highly expressed on primitive hematopoietic stem cells (HSCs) and have been shown to interact with TKIs. Herein we demonstrate a dose-dependent, reversible inhibition of ABCG2-mediated Hoechst 33342 dye efflux in primary human and murine HSC by both imatinib and nilotinib (AMN107), a novel aminopyrimidine inhibitor of BCR-ABL. ABCG2-transduced K562 cells were protected from imatinib and nilotinib-mediated cell death and from downregulation of P-CRKL. Moreover, photoaffinity labeling revealed interaction of both TKIs with ABCG2 at the substrate binding sites as they compete with the binding of [(125)I] IAAP and also stimulate the transporter's ATPase activity. Therefore, our evidence suggests for the role of ABC transporters in resistance to TKI on primitive HSCs and CML stem cells and provides a rationale how TKI resistance can be overcome in vivo. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are short single-stranded RNAs that have a potentially important role in gene regulation. Using a quantitative real-time polymerase chain reaction assay specific to the mature miRNA, the expression level of a selected group of haematopoietic tissue-specific miRNAs was measured across a set of 30 primary adult acute myeloid leukaemia (AML) with a normal karyotype. The expression levels of each miRNA were correlated with the genome-wide mRNA expression profiles in the same leukaemias. This revealed that miR-181a correlated strongly with the AML morphological sub-type and with the expression of genes previously identified through sequence analysis as potential interaction targets. Three other miRNAs, miR-10a, miR-10b and miR-196a-1, showed a clear correlation with HOX gene expression. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented regarding the use of Bortezomib therapy in curing myelofibrosis.